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    2024,Volume 53, Issue 6

      >Nuclear Material
    • Wei Yaxuan, Wang Dingqu, Li Zhengcao, Lv Shasha

      2024,53(6):1601-1607 DOI: 10.12442/j.issn.1002-185X.20230178

      Abstract:Zirconium alloys are used as cladding materials for fuel components in reactors due to their excellent mechanical properties, excellent corrosion resistance and low thermal neutron absorption cross-section. However, Zr-4 can no longer reach the requirements of nuclear power technology under higher burn-up conditions. Therefore, it is of great significance to develop new zirconium alloys by regulating the alloy composition. In this study, Zr-4 and two other new zirconium alloy materials were subjected to conventional tensile tests at room temperature and 315℃. The precipitation phase changes caused by composition differences were analyzed based on the calculation results. And the importance of precipitation strengthening mechanism was proposed for the performance improvement of zirconium alloys. The mechanical properties of zirconium alloy were tested for the first time by using small punch test. The coefficient values related to the zirconium alloy material itself were determined in the empirical formula between the conventional tensile test and the small punch test. The feasibility of the small punch test for the evaluation of the tensile properties of zirconium alloys was verified. Zr-4 and two other new zirconium alloys were hydrogen-charged at 400°C by gaseous hydrogen permeation, and their mechanical properties were tested by SPT. The results show that the hydrogen-charged Zr alloys have a special phenomenon of "platform region" in the plastic instability stage of the load-displacement curve. In this paper, the morphological characteristics of hydrides were characterized by metallographic analysis and their contents was quantitatively estimated. It was speculated that the difference in the fracture toughness between hydrides and matrix, the special long chain configuration of the hydride phase and its strong orientation have an important correlation with this phenomenon.

    • GONG Weijia, CHEN Jichang, ZHANG Jingyi, CHEN Zhaokui, LI Zhongkui, LI Jinshan

      2024,53(6):1608-1615 DOI: 10.12442/j.issn.1002-185X.20230207

      Abstract:The harsh environment with strong acid, high oxidability and irradiation raises urgent demand for advanced structural materials used for reprocessing dissolver of spent nuclear fuels. In this paper, hot compression behavior of a Zr-1.0Ti-0.35Nb alloy was investigated at the strain rates of 0.01, 0.1, 1 s-1 and in the temperature range of 670 ~750 °C. Microstructural evolution during the hot compression was analyzed. The results reveal that the strain rate and deformation temperature both significantly affect the hot deformation behaviour of Zr-1.0Ti-0.35Nb alloy. Flow stress increases with accelerated strain rate, and decreases with elevated temperature. Beyond peak stress, the flow curve exhibits apparent characteristic of dynamic recrystallization characteristics. Elevated deformation temperature favors dynamic recrystallization and grain growth. An Arrhenius-type constitutive model was established based on the obtained peak stress values, in which the activation energy is calculated as 225.8 kJ/mol suggesting a Ti-induced elevation of activation energy and the hardening index is 5.62. A correlation coefficient of 0.97427 and average relative error of 6.15% are obtained between the experimental and predicted values, demonstrating sound applicability of the constitutive model that is expected to guide processing optimization for the new Zr-1.0Ti-0.35Nb alloy.

    • Liu Xin, Tu Menghe, Li Shen, Wang Hui, Hu Yong

      2024,53(6):1626-1631 DOI: 10.12442/j.issn.1002-185X.20230177

      Abstract:Zirconium cladding absorbs hydrogen in the reactor, and the zirconium cladding will embrittlement in the Loss Of Coolant Accident(LOCA). The hydrogen-containing cladding is more likely to rupture in the process of accident or the subsequent treatment of accident, resulting in the leakage of radioactive products. In this thesis, residual plasticity of zirconium alloys with different hydrogen contents (0 ppm, 195 ppm, 315 ppm, 395 ppm) after simulated LOCA was studied, and the effect mechanism of hydrogen on residual plasticity of zirconium alloys during simulated LOCA was explored. The results show that the residual plasticity of zirconium alloy decreases with the increase of hydrogen content. The increase of hydrogen has little effect on the microstructure of zirconium alloy, and the effect of hydrogen on the microstructure of zirconium alloy is not the reason for the reduction of residual plasticity of zirconium alloy. one of the reasons why the presence of hydrogen leads to the decrease of the residual plasticity of zirconium alloy after simulated LOCA is that the increase of hydrogen leads to the increase of oxygen content absorbed by the prior-β phase after quenching, thus reducing the residual plasticity of zirconium alloy. Secondly, hydrogen may exist in the prior-β phase in the form of saturated solid solution or fine hydride brittle phase, which also leads to the decrease of the residual plasticity of zirconium alloy.

    • Gu Zhiyuan, Wu Yue, Lin Xiaodong, Yao Meiyi, Hu Lijuan, Liang Xue, Li Yifeng, Peng Jianchao, Xie Yaoping, Zhou Bangxin

      2024,53(6):1642-1653 DOI: 10.12442/j.issn.1002-185X.20230206

      Abstract:Zr-0.75Sn-1Nb-0.35Fe-0.15Cr (wt.%) alloy plates were prepared by smelting, hot rolling, cold rolling and annealing techniques successively. The samples were then irradiated on an electrostatic accelerator with Ar+ to a fluence of 1.02×1015 and 5.1×1015 ions/cm2 (corresponding to 1 and 5 dpa, respectively) at 300 ℃. Both the unirradiated and irradiated samples were exposed to 360 ℃/18.6 MPa/0.01 M LiOH aqueous solution for 90 d. The microstructures of the alloy matrix before and after irradiation and the oxide film formed after corrosion were characterized by scanning electron microscope and transmission electron microscope. The results showed that before irradiation the alloy was fully recrystallized and the grains were equiaxed. The second phase particles were mainly Zr(Fe,Cr,Nb)2 with a fcc or hcp structure, and their size was within the range of 50~100 nm. After irradiation, -type dislocation loops were observed in the irradiated region of the alloy, and the second phase particles were completely amorphous, but the element diffusion from the second phase particles to the matrix was not found. After 90-d corrosion, the oxide film thickness of the irradiated samples was smaller than that of the unirradiated sample, indicating that Ar+ irradiation decreased the corrosion rate of the alloy to some extent at early stage of corrosion. This can be explained by the fact that Ar+ irradiation could delay the microstructural evolution of oxide film, including reducing the proportion of equiaxed grains and the number of cracks in the oxide film, as well as slowing down the oxidation of amorphous second phase particles induced by irradiation, thus enhancing the protectiveness of the oxide film.

    • Hu Lijuan, Zhang Honglin, Wang Zixuan, Qiang Yuanyuan, Yao Meiyi, Xie Yaoping

      2024,53(6):1654-1665 DOI: 10.12442/j.issn.1002-185X.20230209

      Abstract:The mechanical properties of the prior-β Zr layer in zirconium alloys in loss of coolant accident (LOCA) are of great significance to nuclear safety. Nb as an important alloying element in zirconium alloys, has an important influence on its mechanical properties. In this paper, the phase transformation behavior of Zr-xNb (x=0, 0.5, 1, 2.5; wt.%) alloy during LOCA quenching and tensile behavior after quenching were investigated by molecular dynamics method, and the Nb"s effect on mechanical properties of Zr-xNb was analyzed. The results show that the simulated phase transformation process of quenching leads to lamellar polycrystals similar to the structure of prior-β Zr , which are mainly composed of fcc and hcp structural atoms. The bcc→fcc phase transformation path follows the Brain phase relationship, while the bcc→hcp phase transformation path follows the P-S phase relationship. During the cooling process, the addition of Nb reduces the difference between the free energy of the bcc and hcp phases, thus making the temperature of β to α + β phase transition lower. In the Zr, Zr-0.5Nb and Zr-1Nb alloy models, Nb promotes the generation of bcc phase at the grain boundaries, which makes the deformation concentrated at the grain boundaries thus leads to the fracture of the grain boundaries. In Zr-2.5Nb, the content of Nb in the grain is also higher for the formation of bcc phase, which makes the deformation homogeneous and improves its plasticity. In addition, the clusters of Zr-2.5Nb alloy models are diffusely distributed, which makes the tensile strength of Zr-2.5Nb improved.

    • Zhang Feng, Hu Lijuan, Lin Yuchen, Chen Liutao, Gao Changyuan, Xu Shitong, Xie Yaoping, Yao Meiyi, Zhou Bangxin

      2024,53(6):1666-1676 DOI: 10.12442/j.issn.1002-185X.20230235

      Abstract:The high temperature steam oxidation behaviour of zirconium alloys under Loss of Coolant Accident (LOCA) is one of the issues that needs to be focused on. In this paper, we smelted Zr-xNb (x=0.5, 1.0, 1.5, wt.%) alloys and Zr-1Nb-yCr (y=0.05, 0.2) alloys and prepared them as plate samples. The oxidation behaviour of the five zirconium alloys in steam at 900~1200 °C under simulated LOCA conditions was investigated using a simultaneous thermal analyser. And the microstructure and microhardness of the samples before and after oxidation were studied using a metallographic microscope and a microhardness tester, respectively. The results show that the oxidation resistance to high-temperature steam of Zr-xNb alloys does not vary monotonically with the change of Nb content at 900~1100 °C, and changes with temperature; the addition of Cr makes the oxidation resistance to high-temperature steam of Zr-1Nb alloys worse, and the effect is complicated; overall, the Zr-1.5Nb alloy has the best performance at 900~1100 °C. When oxidized in steam at 1200 °C, the addition of Nb and Cr has little effect on the oxidation resistance to high temperature steam of the alloys.With increasing temperature, the oxidation kinetic of the five alloys undergoes a parabolic → linear transition with multiple transitions. Finally, the mechanism that Nb and Cr affect the high temperature steam oxidation behaviour of zirconium alloys has been investigated from the following perspectives: the solid solution content of O in the Zr matrix, the α?β phase transition of the Zr matrix and the monoclinic (m) ? tetragonal (t) phase transition of the oxide film.

    • >Materials Science
    • Wang Boya, Luo Yumeng, Liu Rui, Song Xiaoyun, Yu Yang, Ye Wenjun, Hui Songxiao

      2024,53(6):1517-1522 DOI: 10.12442/j.issn.1002-185X.20230553

      Abstract:The deformation behavior of pure Ti, Ti-0.2wt% O, and Ti-0.4wt% O polycrystals under high strain rate was investigated by quasi-in-situ EBSD and SEM observation. Results show that under dynamic compressive deformation of 5% strain, the twinning behavior in pure Ti is very active, the twins in most grains are activated, and multiple twin variants appear in half of the grains. However, the slip trace analysis shows that the slip systems are activated in only 50% grains. With the increase in oxygen content, the proportion of twins and the twin area ratio are decreased, and multiple slips and cross slip are activated in the meantime. XRD analysis reveals that the solute oxygen atoms cause the lattice distortion and increase the c/a ratio in α-Ti, which is beneficial to the dislocation slip. The active dislocation slip inhibits the twin nucleation, and the oxygen atoms can pin dislocations to hinder the expansion of twinning boundaries. Thus, the twinning behavior is no longer active. In addition, the dynamic yield strength of pure Ti increases by about 390 MPa for every 0.2wt% increase in oxygen content. This solution hardening phenomenon mainly originates from the lattice distortion, and it is also influenced by the pinned dislocations and the jogs resulting from multiple slips and cross slip.

    • Wang Huigai, Zhang Keke, Wang Bingying, Wang Yaoli

      2024,53(6):1523-1535 DOI: 10.12442/j.issn.1002-185X.E20230029

      Abstract:Sn2.5Ag0.7Cu0.1RE0.05Ni lead-free solder alloy was used as the research object. Based on the unique structure, excellent physical properties, and good mechanical properties of graphene nanosheets (GNSs), the Ni modified GNSs (Ni-GNSs) were used as the reinforcement phase. The soldering process of Ni-GNSs reinforced SnAgCuRE system composite solder/Cu and thermal aging tests of soldering joints were conducted to investigate the effect of Ni-GNSs on the microstructure and thermal aging fracture mechanism of composite soldering joints. Results show that the addition of Ni-GNSs inhibits the linear expansion of the composite solder, resulting in lattice distortion and dislocation. The intermetallic compound (IMC) particles near the dislocation line interact with the dislocations and hinder their movement, thereby strengthening the composite solder and further improving the soldering joint. With a longer thermal aging time, the thickness of interface IMC layer is increased and the shear strength of soldering joints is decreased. Among them, the shear strength decrement of the composite soldering joints with 0.05wt% GNS addition is the least of only 8.9%. Moreover, after thermal aging for 384 h, its shear strength is still higher than that of the Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu soldering joint before thermal aging. With the addition of Ni-GNSs, the growth coefficient of interface IMC of composite soldering joints is significantly reduced, which effectively alleviates the degradation of mechanical properties of composite solder/Cu soldering joints during the thermal aging process, further changes the thermal aging fracture mechanism of composite solder/Cu soldering joints, and ultimately affects the reliability of joints. The fracture position of the Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu soldering joints moves from the soldering seam before thermal aging to the soldering seam/interface IMC, presenting the ductile-brittle mixed fracture. The fracture position of the Sn2.5Ag0.7Cu0.1RE0.05Ni-0.05GNSs/Cu soldering joints is still in the soldering seam zone, presenting the ductile fracture, which indicates the high reliability of the soldering joints.

    • Wang Chunshui, Wu Haiyan, Jiao Cheng, Chu Xiangfeng, Liang Shiming, He Lifang

      2024,53(6):1536-1542 DOI: 10.12442/j.issn.1002-185X.E20230035

      Abstract:A series of C3N4/CuGaO2 composites were synthesized by facile hydrothermal method. The prepared samples were characterized by XRD, SEM, TEM, and XPS. The gas sensing properties of the C3N4/CuGaO2 composites were investigated. Results demonstrate that the gas sensor based on C3N4/CuGaO2-0.3 composite (molar ratio of C3N4 to CuGaO2 is 0.3:1) shows better sensing performance to toluene than CuGaO2 sensor does. Compared with the operating temperature of CuGaO2 sensor (140 °C), the optimal working temperature of C3N4/CuGaO2-0.3 composite sensor is only 25 °C, the response to 100 μL/L toluene gas reaches 28, and the detection limit is as low as 0.01 μL/L. The response time and recovery time for the detection of 100 μL/L toluene vapor are 114.2 and 27.4 s, respectively. Moreover, the C3N4/CuGaO2-0.3 composite sensor also exhibits excellent long-term stability, good repeatability, and extraordinary humidity resistance for toluene detection.

    • Xu Minglei, Lu Wenli, Zhang Xiaowei, Chen Dehong, Li Jinying, Yu Chuang, Yang Wensheng, Wang Zhiqiang

      2024,53(6):1543-1548 DOI: 10.12442/j.issn.1002-185X.20230556

      Abstract:Metal Y was purified by plasma zone melting, and the migration laws of Al, Si, Fe, Ni, Cu, and Mo impurities during the zone melting purification process were obtained. Calculation results show that the equilibrium distribution coefficients of the Al, Si, Fe, Ni, Cu, and Mo impurities in metal Y are 0.2173, 0.2201, 0.5065, 0.1586, 0.1742, and 0.8576, respectively. Because all equilibrium distribution coefficients are less than 1, the solubility of impurities in the liquid phase is greater than that in the solid phase. Therefore, theoretically, with the movement of molten zone, the Al, Si, Fe, Ni, Cu, and Mo impurities will be concentrated in the tail side of Y metal ingot, namely last-to-freeze zone. Experiment results demonstrate the correctness of the theoretical calculation. Besides, the internal relationship between the zone melting times and the impurity migration was investigated. Results show that with the increase in the zone melting time from 5 to 10, the concentration degree of impurities at the tail side of Y metal ingot is increased, i.e., the removal ratio is increased. After 10 times of zone melting, the removal ratios of Al, Si, Fe, Ni, Cu, and Mo impurities are 45.71%, 61.54%, 33.98%, 64.15%, 52.14%, and 46.28%, respectively. Because the saturated vapor pressure of the abovementioned impurities is similar to that of metal Y, impurities are difficult to be removed by the common methods. The investigation of plasma zone melting proposes a new research direction for the preparation of high purity Y.

    • Yin Qi, Yuan Xiaoming, Zhang Jiantong, Feng Fan, Yang Hongguang

      2024,53(6):1549-1554 DOI: 10.12442/j.issn.1002-185X.20230599

      Abstract:Fe-Al/Al2O3 composite coating was prepared through rare earth-modified aluminizing and in-situ oxidation at 760 °C. The microstructure and phase distribution of the aluminizing layer and oxide film were investigated. Results show that the rare earth-modified aluminizing layer can be divided into three layers: an outer aluminizing layer, a transition layer, and an inner diffusion layer. The aluminizing layer is predominantly composed of FeAl phase and Fe3Al phase. Notably, the FeAl phase is primarily concentrated in the outer layer of aluminizing layer, providing favorable conditions for selective oxidation of the Al2O3 oxide film. The surface of oxide film exhibits the α-Al2O3 ridge structure. Additionally, the presence of Ce oxide on the surface is attributed to the outward diffusion of Ce and its preferential reaction with O2 during the initial oxidation stage. The oxide film can be divided into two layers, namely a pure α-Al2O3 layer and a transition layer which is mainly composed of α-Fe(Al) and mixed oxides of Al, Fe, and Ce.

    • He Miaoxia, Yan Chi, Dong Yuecheng, Chang Hui, V Alexandrov Igor

      2024,53(6):1555-1565 DOI: 10.12442/j.issn.1002-185X.20230547

      Abstract:The effects of Mn microalloying on the microstructure and mechanical properties of new near-α Ti-Al-Mo-Zr-Fe-B alloy were studied by OM, EBSD, and TEM. Results indicate that the addition of 0.5wt% Mn can refine the casting microstructure of the alloy from 3.28 μm to 2.65 μm, which leads to the increase in ultimate tensile strength from 882 MPa to 966 MPa. However, the elongation decreases from 7.8% to 5.1%. After forging, the grain size of two alloys tends to be similar, and the microstructure is more equiaxed. Besides, the microstructure becomes more homogeneous after Mn microalloying. The ultimate tensile strength and elongation of Ti-Al-Mo-Zr-Fe-B alloy increase to 966 MPa and 16.4%, respectively, whereas the alloy containing 0.5wt% Mn element possesses higher ultimate tensile strength, reaching 1079 MPa. Meanwhile, the elongation reaches 15.8%. These results suggest that the increase in strength can be attributed to the solid solution strengthening effect of Mn element. Additionally, the Mn microalloying promotes the enrichment of Al element in alloy into the α phase, which is beneficial to improve the strength and plasticity of the alloy.

    • Yang Yu, Chen Geng, Li Hui, Liang Jinglong, Hu Meilong, Hu Mengjun

      2024,53(6):1566-1573 DOI: 10.12442/j.issn.1002-185X.20230580

      Abstract:The nanoscale (VNbTaZrHf)C high-entropy carbide (HEC) powders with face-centered cubic structure were prepared by electro-deoxidation of metal oxides and graphite in CaCl2 at 1173 K. Appropriate temperature conditions are favorable for suppressing the in-situ sintering growth of HEC particles. Electrochemical performance tests were conducted in 1 mol/L KOH solution to investigate the catalytic performance of (VNbTaZrHf)C HEC. The catalytic performance of (VNbTaZrHf)C HEC for hydrogen evolution reaction (HER) was evaluated through polarization curves, Tafel slope, electrochemical impedance spectroscopy, and double-layer capacitance value cyclic voltammetry tests. Results show that the double-layer capacitance value of (VZrHfNbTa)C HEC is 40.6 mF/cm2. The larger the double-layer capacitance value, the larger the electrochemically active surface area. Due to the high-entropy effect and nanoscale structure of (VNbTaZrHf)C HEC, it exhibits superior catalytic performance to HER. This research provides a novel method for the preparation of HECs via molten salt electro-deoxidation.

    • Chao Rui, Cai Haichao, Li Hang, Lv Wenxue, Xue Yujun

      2024,53(6):1574-1581 DOI: 10.12442/j.issn.1002-185X.20230564

      Abstract:In order to explore the effects of Ti doping on the optical and mechanical properties of Ta2O5 coatings prepared by Ar/N2-Ar co-sputtering, Ta2O5, N2-Ta2O5, Ti-Ta2O5, and N2-Ti-Ta2O5 coatings were prepared on the glass substrate surface by radio frequency and direct current magnetron co-sputtering techniques. The microstructures and surface morphologies of Ta2O5, N2-Ta2O5, Ti-Ta2O5, and N2-Ti-Ta2O5 coatings were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and atomic force microscope (AFM). The optical parameters of the coatings were tested by ultraviolet-visible spectrophotometry. The hardness and Young's modulus of the coatings were tested by nanoindentation. XRD test results show that the Ta2O5, N2-Ta2O5, Ti-Ta2O5, and N2-Ti-Ta2O5 coatings mainly consist of amorphous phase structure with Ta2O5 as the main body. SEM and AFM results show that the coatings deposited on the glass substrate do not have extensive voids. The sputtered particles are uniformly piled and grow on the substrate surface. The coating thicknesses are basically the same and the thickness error is within 5%. The separate introduction of N2, Ti, and N2-Ti co-doping can reduce the roughness of Ta2O5 coatings. The optical test results show that the separate introduction of N2 and Ti element can increase the average transmittance of Ta2O5 coatings to more than 81%, whereas the average transmittance of N2-Ti-Ta2O5 coatings prepared by N2-Ti co-doping reduces. Mechanical test results show that compared with that of Ta2O5 coating, the hardness of N2-Ta2O5 and N2-Ti-Ta2O5 coatings increases significantly. The hardness of Ti-Ta2O5 coatings is basically the same. The elasticity index (H/E) and plasticity index (H3/E2) indicate that the N2-Ta2O5 and N2-Ti-Ta2O5 coatings possess better fracture toughness and plastic deformation resistance. The preparation of N2- and Ti-doped Ta2O5 coatings on glass surface can obtain the multifunctional coatings with both excellent optical and mechanical properties, which is represented by N2-Ta2O5 and N2-Ti-Ta2O5 coatings.

    • Qiao Xudong, Chen Minghe, Xie Lansheng

      2024,53(6):1582-1591 DOI: 10.12442/j.issn.1002-185X.20230472

      Abstract:In order to solve the problems of insufficient forming of complex box part in the single deep drawing, a precise hot forming process of deep drawing and gas bulging was proposed, and the shape and thickness of the formed parts could meet the design requirements. TC2 titanium alloy complex box part was selected as the research object in this research. The high temperature formability of TC2 titanium alloy was investigated at 550–800 °C and 0.001–0.1 s-1. A set of mold for deep drawing and gas bulging at one time was designed. The forming process of the complex box part was simulated based on the finite element simulation software PAM-STAMP, and the optimized process parameters were obtained and verified by experiments. Results show that the simulation software PAMSTAMP can effectively predict the part defects during deep drawing and gas bulging. The process parameters and mold shape are ameliorated and verified by experiments. Complex box part with thickness and height meeting the design requirements can be obtained under the conditions of 800 °C and gas pressure of 2.5 MPa, which verifies the feasibility of the composite process of deep drawing and gas bulging.

    • Zhang Wenbin, Yang Haijuan, Liu Cuirong, Li Yan, Shi Aizun

      2024,53(6):1592-1600 DOI: 10.12442/j.issn.1002-185X.20230600

      Abstract:In order to reduce cost and to fully utilize the excellent corrosion resistance of nickel materials, pure nickel N6 with thickness of 1 mm was selected as the flyer plate, and the medium carbon steel 45# with thickness of 3 mm was used as the base plate for explosive welding tests. The dynamic parameters were calculated through the explosive welding window, and the interface bonding morphology and elements were analyzed by metallographic optical microscope and scanning electron microscope. The mechanical properties of the composite plate were tested through shear tests, and the explosive welding process was simulated by AUTODYN. Results indicate that there is a boundary effect near the explosion point, and the bonding interface along the explosion welding direction changes from the flat state to the stable wavy interface. The thickness of the element diffusion layer near the interface is 20 μm, and the wavy diffusion layer increases the bonding area, which is conducive to the metallurgical bonding. The shear strength of the composite plate reaches 325.5 MPa. Numerical simulation analysis results demonstrate that the simulated interface morphology is consistent with the experiment results. The simulation results show that the velocity and plastic deformation degree of the characteristic points are basically consistent with the experimental results.

    • Wang Qiangli, Zhong Hong, Li Dou, Zheng Hanyu, Hu Zhongwu, Gao Xuanqiao, Zhang Wen, Li Shuangming

      2024,53(6):1616-1625 DOI: 10.12442/j.issn.1002-185X.20230226

      Abstract:The microstructure evolution of Al7(CoCrFeMnNi)93 high-entropy alloy was studied by directional solidification technology. Then single crystals of high-entropy alloy with cellular and dendritic substructures were prepared by the natural competitive growth method. Finally, the effect of substructure and orientation on the nano-mechanical properties of high-entropy alloy single crystals was studied. The results show that the growth interface of Al7(CoCrFeMnNi)93 high-entropy alloy is more prone to destabilization during directional solidification. Its planar-cellular solidification interface morphologies transition rate is less than 1 μm/s, and the cellular-dendritic solidification interface transition rate ranges from about 2 to 5 μm/s. The primary dendrite arm spacing and the secondary dendrite arm spacing of the alloy decrease gradually with the increase of directional solidification rate and satisfy the exponential relationship with the withdrawal rate respectively. After directional solidification, the elements of Co, Cr, and Fe were enriched in the dendrite region, while the elements of Mn, Ni, and Al with lower melting temperatures tend to be enriched in the inter-dendrite region. The orientation of the cellular and dendritic substructures single crystal obtained by the natural competition method are [2 1 4] and [2 1 3], respectively. The data of nano-indentation mechanical properties show that the substructure caused by segregation behavior has little effect on the elastic modulus and hardness of single crystals, while the crystal orientation has a greater influence on the elastic modulus of single crystals, but has little effect on the hardness value.

    • Shen Tao, Mu Chengfa, Cao Xudan, Liu Zhenwu, Chen Linchi, Chen Xiao, Yang hui

      2024,53(6):1632-1641 DOI: 10.12442/j.issn.1002-185X.20230204

      Abstract:Silver-based electrical contact materials are the core of low-voltage electrical connection in the fields of new energy power vehicles, industrial electrical appliances and other fields, with the widest range of applications and the largest demand. The Ag/SnO2 contact material system has made great progress due to its excellent electrical contact performance and arc erosion resistance. However, the material system still has problems such as higher temperature rise and shorter electrical life under service. Once it fails, it will lead to major safety accidents such as power system paralysis and out-of-control communication facilities, and economic and social losses are difficult to estimate. Herein, in order to explore the impact of the type and content of the modified components on the preparation process, microstructure, microhardness, temperature rise and electrical life of the modified Ag/SnO2In2O3 contact materials, the modified AgSnIn alloys are synthesized by medium-frequency smelting and casting process, and then the corresponding Ag/SnO2In2O3 contact materials are prepared by internal oxidation method. The AC-4 electrical life type testing platform is used to evaluate the temperature rise and electrical life performance of the materials. The results shows that the optimum parameters of internal oxidation process of the modified Ag/SnO2In2O3 materials are 700℃, 5MPa, 48h. Compared with the binary modification of Ni, Cu or Zn, there exists larger micro-strain in the Ni-Cu-Zn ternary modified AgSnIn alloys, and the microhardness of the corresponding modified Ag/SnO2In2O3 material increases first and then decreases sharply with indium content decreased. The modified AgSnIn alloy, composed of 0.47wt.% nickel, 0.4wt.% copper, 0.43wt.% zinc and 2.1wt.% indium element, could achieve complete internal oxidation. The corresponding modified Ag/SnO2In2O3 material presents the optimum microhardness (1382.49 MPa), the longest cycle number (28989 operations) and the appropriate temperature rise (43.69 K), which is attributed to some larger micro-strain (19×10-3) and grain boundary structure with strengthening effect. By comparison analysis, A positive correlation has been established between the electric life cycle number and the microhardness of the modified Ag/SnO2 material Within In element content ranged from 2.1 to 3.1 wt.%, which will provide a new idea for the formulation design and electric life performance prediction of the Ag/SnO2 contact material.

    • Xiao Peng, Yang Kai, Yu Yiping, Wang Song, Liu Haibo

      2024,53(6):1677-1684 DOI: 10.12442/j.issn.1002-185X.20230193

      Abstract:Ta/Ta0.5Hf0.5C laminated composite shows great potential to be used as wing leading edges and nose caps due to its good mechanical properties and ablation resistance. However, the thermal shock behavior of the composite is rarely reported for now, as such, it is hard to evaluate whether the composite can serve as a structural material stably. In this paper, the plasma flame and finite element method (FEM) were employed to investigate the thermal shock behavior of Ta/Ta0.5Hf0.5C laminated composite. By analyzing the morphologies and microstructure of the tested sample, it is found that Ta/Ta0.5Hf0.5C laminated composite possesses great thermal shock resistance since no cracks were observed on the internal and external surfaces of the composites after 120 cycles of plasma flame pulse assessment. Based on the measured temperature results during thermal shock testing, the thermal stress distribution field inside the testing sample was built successfully, and it reveals the maximum thermal stress (207 MPa) caused by plasma flame occurs at the moment of cooling. After 120 cycles of stress cycling, the retention rates of strength and toughness of the composites are 70.1% and 73.9%, respectively. High strength and excellent crack propagation resistance are the main reasons for the excellent thermal shock resistance of Ta/ Ta0.5Hf0.5C laminated composite.

    • Yang Xirong, Chu Xiaoqing, Li Zhao

      2024,53(6):1685-1692 DOI: 10.12442/j.issn.1002-185X.20230228

      Abstract:This article investigates the effects of electrolyte temperature and pH on the electrochemical crystallization behavior of copper through cyclic voltammetry (CV) and chronoamperometry (CA) experiments. The effects of electrolyte temperature and pH on the phase composition, preferred orientation, microstructure, roughness, and hardness of copper electrodeposited layers were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), three-dimensional ultra depth of field microscopy and microhardness tester. The results indicate that the copper electrocrystallization process is a three-dimensional nucleation and growth mode controlled by diffusion. When the electrolyte temperature is 35 ℃, the electrodeposition efficiency of copper is the highest; When the pH value of the electrolyte is 9, the promotion effect on copper electrodeposition is optimal. The final nucleation mechanism of different electrolyte temperatures and pH values is three-dimensional instantaneous nucleation growth. With the decrease of electrolyte temperature and the increase of pH value, the preferred orientation changes from (111) crystal plane to (220) crystal plane. When the electrolyte temperature is 35 ℃ and pH is 9, a flat, dense, rough and hard electrodeposited copper layer can be obtained.

    • YU Chao, GUO Yunchang, XIAO Zihan, JIANG Runwu, HE Zhibin, XIAO Hong

      2024,53(6):1693-1700 DOI: 10.12442/j.issn.1002-185X.20230222

      Abstract:In order to achieve a more uniform temperature distribution during electromagnetic induction heating of titanium plate rolled at different temperature of titanium and aluminum, different induction heating coil sets are designed to heat the titanium plate, and the influence of the structural parameters of the induction coil on the temperature field in electromagnetic induction heating is simulated by using finite elements, and the temperature difference between the width of the titanium plate is controlled within 50 °C by adjusting the induction heating parameters to form a more uniform temperature of the titanium plate. The induction heating and temperature measurement experiments of the titanium plate were carried out, and the average temperature of the titanium plate was formed under a short heating time of 635 °C, and the temperature difference within 45 °C was formed, which verified the correctness of the simulation results. A titanium/aluminum composite plate with an interface shear strength of 63.3MPa was prepared by rolling the high-temperature titanium plate and the room-temperature aluminum alloy plate with good uniformity, and the distribution of the bonding performance of the prepared titanium/aluminum composite plate was analyzed by temperature uniformity.

    • 李萍, Ding Ruidong, Zhang Yongqiang, Shi Chengfeng, Zhi Qiang, Xue Kemin

      2024,53(6):1701-1708 DOI: 10.12442/j.issn.1002-185X.20230224

      Abstract:In this study, the effect of different number densities of O-phase on the mechanical properties of the matrix B2 phase in Ti2AlNb alloy was investigated based on molecular dynamics. The results show that the yield strength and plasticity of the B2 phase are improved when the O phase is contained. This is because the precipitated phase hinders the start of the slip system in the matrix during the tensile deformation process, thereby improving the plastic deformation resistance of the B2 phase of the matrix. It is found that the improvement of material plasticity is mainly related to the release of internal stress, in which the release of internal stress by the B2 phase through martensitic phase transition is dominant, and the release of internal stress by dislocation is secondary. When the matrix B2 phase contains the O phase, the O relative dislocation hindrance will lead to stress concentration, thereby inducing martensitic phase transition of a large number of BCC structures, and the degree of stress concentration in this process decreases, delaying the growth of pore nuclei. On the other hand, since the O phase is a ductile phase, the growth of holes at the boundary between the O phase and the B2 phase is inhibited, so that the plasticity and toughness of Ti2AlNb alloy are greatly improved. And with the increase of the density of the number of precipitated phases, the yield strength and yield strain of the material decrease, but its strength and plasticity are still improved compared with those without the O phase. This is because, with the increase of O phase number density, the proportion of martensitic phase transition of the matrix atoms during the deformation process decreases, so the release degree of the stress concentration by the phase transition decreases, and the generation and expansion rate of the holes increases, so that the material is more prone to fracture failure.

    • Liang Chaoqun, Yaojunping, Li Yiran, Li Buwei, Chen Guoxin

      2024,53(6):1709-1717 DOI: 10.12442/j.issn.1002-185X.20230263

      Abstract:Based on the real microstructure of composite materials and introducing cohesive element units at the interface between particles and matrix, four finite element models with different particle aggregation distributions (uniform distribution, aggregation at three locations, aggregation at two locations, and aggregation at one location) were established to investigate the influence of particle aggregation on the crack initiation and propagation mechanisms of SiC/AZ91D composite materials. The results show that when the crack initiates, stress distribution in the matrix is highly uneven, with the maximum stress occurring at the corners of the particle group. The more severe the particle aggregation, the greater the maximum stress value during crack initiation. As the crack propagates, the greater the degree of particle aggregation, the higher the maximum stress value in the matrix and the greater the extent of crack propagation. When the crack completely fractures, the maximum stress value of the particles gradually increases with the aggravation of particle aggregation, while the maximum stress value of the matrix remains relatively constant. Particle aggregation accelerates the process of crack initiation and propagation, and particles are uniformly distributed in the matrix. The crack initiation and propagation mechanism of composite materials is due to the severe stress concentration at the boundaries and corners of the SiC particle group, which causes damage to the matrix, initiates microcracks, and then propagates along the direction of maximum shear stress to form the main crack.

    • Fang Haoxin, Liu Wei, Yang Yunfei, Zhou Fan, Wang Jinshu

      2024,53(6):1718-1725 DOI: 10.12442/j.issn.1002-185X.20230243

      Abstract:In this paper, rhenium-tungsten core-shell powder was prepared by solid-liquid mixing method and then osmium powder was added to prepare ternary mixed powder with special coating structure after pretreatment. After the powder was pressed, sintered, impregnated with salt, washed and annealed, a ternary mixed-base cathode of tungsten-rhenium osmium was prepared. After impregnation with 411 salt, the pulse emission test found that W2Re1Os1 cathode which is a ternary mixed-base cathode has the best electron emission performance and the current emission density can reach 35 A/cm2 at 1050℃, which is slightly higher than that of the same type of binary mixed-base cathode, reaching the level of the ternary film cathode covered with tungsten, rhenium and osmium. It is verified by experiments that neither Re nor Os reacts with the active salt during the impregnation process of the ternary tungsten-rhenium-osmium mixed-base cathode, and the active substance is produced by the reaction of W and the active salt.

    • TIAN Wei, ZHANG Shaoping, ZHONG Yan, FU Rui, LI Fulin

      2024,53(6):1726-1734 DOI: 10.12442/j.issn.1002-185X.20230259

      Abstract:S110 cast steel shot and Z300 ceramic shot were used to do the shot peening experiment, the morphology of shot peening surface was observed by scanning electron microscopy (sem) and three-dimensional contour instrument. The residual stress of shot peening surface was tested by X-ray diffraction method, the microstructure of cross section of shot peening layer was analyzed by optical microscope(OM) and electron backscattered diffraction(EBSD). The reselut shows that with the increase of shot peening intensity the roughness of shot peening surface is increased. The roughness of ceramic shot peened surface is lower than that of cast steel shot peened. Residual compressive stress on the cast steel shot peening surface is between - 860 Mpa to -1000 Mpa and with the increase of shot peening intensity of residual compressive stress is slightly reduced. Residual compressive stress on the ceramic shot peening surface is between - 1000 Mpa to -1100 Mpa and with the increase of shot peening intensity of residual compressive stress is slightly insreased. After shot peening, projectile pits are formed on GH4096 alloy surface, plastic deformation occurs, grain boundaris are curved, lattice deformation appears, cause a lot of dislocation set and low angle grain boundaries, and the grain orientation changes. The 650 ℃ high temperature fatigue life of GH4096 alloy can improve by shot peening, double shot peening promotion of fatigue life is the most obvious, ceramic shot peening strengthen effect is better than that of cast steel shot. The strengthening effect of shot peening are mutual influenced by residual stress, surface roughness and depth of strengthening layer.

    • Xu Jin-liang, Song Yi-fan, Ding Rui-zhi, Yan Hong, Chen Rong-shi

      2024,53(6):1735-1740 DOI: 10.12442/j.issn.1002-185X.20230223

      Abstract:This article uses metallographic and EBSD techniques to study the effects of equal channel angular pressing on the microstructure and mechanical properties of two binary alloys, Mg-1Gd and Mg-2Zn. The results show that under the same pressing conditions, Mg-2Zn alloy fully recrystallized, resulting in grain growth and coarsening, and the strength and plasticity did not change with the number of pressing passes. Mg-1Gd alloy only partially recrystallized after pressing, with a microstructure consisting of fine dynamic recrystallized grains and deformed grains. With an increase in the number of pressing passes, the degree of recrystallization increased, leading to a doubling of the alloy"s tensile strength and plasticity. This was related to the greater inhibition of recrystallization and grain growth by the solute atom Gd compared to Zn. The recrystallized grains had a dispersed orientation, while the grains that did not recrystallize in Mg-1Gd alloy had a c-axis orientation that deviated 45° from ED to TD, which was consistent with the detection of macroscopic texture. A large number of small-angle grain boundaries formed within the grains, and rotations around the c-axis occurred on both sides of these boundaries, gradually evolving into large-angle boundaries.

    • Jiao Kexin, Suo Jun, Yu Kunpeng, Bu Hengyong, Li Fengxian, Liu Yichun, Olim Ruzimuradov, Li Caiju, Fang Dong

      2024,53(6):1741-1748 DOI: 10.12442/j.issn.1002-185X.20230270

      Abstract:Indium tin (InSn) alloy nanowires were prepared using anodic aluminum oxide (AAO) film as template through vacuum mechanical injection method. Ru particles were then coated on the surface of InSn nanowires using the "in situ discharge reduction" method. Subsequently, the tin oxide nanowires (ITO NWs) was obtained by heat treatment of the composite material. Finally, RuO2/ITO NWs were reduced in H2 atmosphere to obtain Ru/ITO NWs. The results indicate that the diameter of InSn nanowire is about 40 nm and Ru nanoparticles of 2-5 nm are uniformly coated on the surface of ITO NWs. In addition, the catalytic pyrolysis of cellulose by Ru/ITO NWs was tested and the main products were 1,6-anhydropyranose, glycoladehyde, and hydroxyacetone. Compared the catalysate of ITO NWs without catalysts, Ru/ITO NWs catalyst reduces the production of 1,6-anhydropyranose, indicates that Ru nanoparticles exacerbate the fracture of oxygen bridges during pyrolysis, accelerate the generation of glycoladehyde and hydroxyacetone, and improve the pyrolysis efficiency. At the same time, the pyrolysis of nonylphenol polyoxyethylene ether with ether bonds is also carried out, and the result shows that Ru/ITO NWs plays a role in the fracture of ether bonds.

    • Li Zhenliang, Wang Xin, Ling Sihan, Zhang Zhihao, Zhao Fan

      2024,53(6):1749-1760 DOI: 10.12442/j.issn.1002-185X.20230252

      Abstract:The trapezoidal continuous casting billet Al-5Ti-1B-0.2Cu intermediate alloy was investigated by solid solution treatment at different solid solution temperatures, followed by transverse and longitudinal hot compression deformation at different deformation temperatures, different deformation rates and different deformation directions. To study the effects of Cu element addition, solid solution treatment and hot compression on the microstructure and dimensional inhomogeneous deformation of second phase particles. The results show that there are four types of second phase particles (Ti1-X,AlX)B2, Al7Cu2Fe, TiB2 and TiAl3 after solid solution treatment at 600 ℃/4h. When Cu is present, the Al-Cu-Fe phase is generated to increase the number of particles in the second phase. At the same deformation degree and deformation temperature, the average size of TiAl3 particles decreases with increasing deformation rate (0.01, 0.1, 1s-1), while TiB2 particles tend to be more diffusely distributed. The second phase particles TiAl3 are more uniform after transverse compression deformation, but the TiAl3 particles are finer after longitudinal compression deformation, while the size and distribution of TiB2 particles in transverse compression and longitudinal compression are basically the same. The dimensional inhomogeneous plastic deformation of the trapezoidal continuous casting billet is more favorable to the size and distribution of the second phase particles TiAl3 and TiB2.

    • Wang Ning, Yang Fan, Ye Xiaoyu, Shao Changcheng, Du Guangyu, Jiang Wenquan

      2024,53(6):1761-1769 DOI: 10.12442/j.issn.1002-185X.20230208

      Abstract:In order to study the effect of vacancy defects on the damping performance of γ-TiAl coating, molecular dynamics (MD) was used to simulate the reciprocating vibration of γ-TiAl coating with different vacancy concentration. The changes of stress-strain, stored potential energy, dislocation line density, defect area and microstructure were compared and analyzed. The results show that with the increase of vacancy concentration, the energy consumption of γ-TiAl coating increases gradually, and the damping performance is enhanced obviously. The stored potential energy of γ-TiAl coating with different vacancy concentration changes periodically, and the range of variation decreases gradually with the increase of vacancy concentration. In the process of vibration simulation, vacancy defects will evolve into dislocation lines and other defects, resulting in increased dislocation density and defect area. The movement, evolution and annihilation of different defects are the main sources of energy consumption of γ-TiAl coating. In addition, the high altitude concentration of γ-TiAl coating produces more plastic deformation, neck shrinkage and more holes, which further increases the energy dissipation.

    • >Reviews
    • Dong Zhijie, Fu Qiangang, Hu Dou

      2024,53(6):1770-1780 DOI: 10.12442/j.issn.1002-185X.20230159

      Abstract:Thermal barrier coatings (TBCs) are one of the effective ways to raise the upper limit operating temperature of aero-engine hot end components. Rare earth zirconate (RE2-xZr2+xO7+x/2) is considered as a candidate material for the new generation of thermal barrier coatings due to its low thermal conductivity and good high-temperature phase stability. In this paper, given to the strong performance designability, domestic and international research progress on mechanical, thermophysical and corrosion resistance of conventional alloying modified and high entropy modified rare earth zirconate coating have been reviewed based on the alloying design idea, and the prospect future for subsequent research has been proposed based on the deficiency of current research.

    • ZHANG Yingxiao, ZHOU Fan, LAI Chen, ZHENG Zhenghui, WANG Ying, ZHOU Wenyuan, WANG Jinshu

      2024,53(6):1781-1796 DOI: 10.12442/j.issn.1002-185X.20230265

      Abstract:Carbon nanotubes (CNTs) are tubular structures composed of highly graphitized atoms. Due to the sp2 hybrid electron orbital structure, CNTs possess a variety of fancy physical and chemical properties, such as high mechanical strength, excellent optical anisotropy and good electrical conductivity. Therefore, CNTs are promising advanced materials that can be used in areas of material strengthening, energy conversion and electronic devices. The structures and properties of CNTs can be tuned by regulating the growth environment of CNTs. Nevertheless, the growing process of CNTs is very complicated, and highly depended on raw material, preparation method and growth environment, which consequently determine the growth rate, microscopic morphologies and final properties of CNTs. Here, the effects of fabrication methods, substrates, catalysts, and growth environment on the microscopic morphologies and properties of CNTs are reviewed, and the growth mechanisms of CNTs are discussed. We also pay attention on the application of CNTs in the areas of energy storage, material toughening and catalytic hydrogen production. The present deficiencies and future development directions on the preparation and controlled growth of CNTs are figured out, which provides guidance for the controlled growth and large-scale preparation of CNTs.

    • Zhang Jianyu, Chen Yayu, Yang Guoqiang, Lü Zheng, Liu Hongji, Ma Penghui, Zeng Hongtao, Li Hezong

      2024,53(6):1797-1816 DOI: 10.12442/j.issn.1002-185X.20230194

      Abstract:The Ti-Al system intermetallic compounds and composites fabricated through Ti and Al,such as TiAl3, γ-TiAl and α-Ti3Al intermetallic compounds, and Ti/Al, Ti/Ti3Al, Ti/TiAl, Ti/TiAl3 and Al/TiAl3 metal-metal and metal-intermetallic compound composites, have good application prospects in aerospace, automotive and other fields owing to their excellent physical, chemical and mechanical properties. The preparation of the above materials involves a variety of Ti-Al reaction diffusion processes. Therefore, an in-depth understanding of the Ti-Al reaction diffusion mechanism and kinetics will help to prepare Ti-Al intermetallic compounds and composites reasonably and efficiently. At present, the Ti-Al reaction diffusion mechanism and kinetics has been extensively studied, but there are still many divergences on some conclusions. In this paper, the research progress of the reaction diffusion mechanism and kinetics involved in the preparation of Ti-Al intermetallic compounds and composites is reviewed, and the future research direction of Ti-Al reaction diffusion is prospected.

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    • Zhang Yingying, Wang Xuebing, Xiong Ning, Liu Xuequan

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240088

      Abstract:The W-25Re alloy was prepared by selective laser melting (SLM) using spherical W-25Re (mass fraction, %, hereinafter) alloy powder as the raw material. The effects of process parameters on the relative density, microstructure and micro-Vickers hardness of W-25Re alloy were investigated. The relative density, microstructure, phase composition, and micro-Vickers hardness of W-25Re alloy were characterized by analytical balance, field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), microhardness tester. The results show that there are no obvious spheroidization, warping, deformation, delamination or non-forming phenomena during the preparation of W-25Re alloy by SLM. There are no obvious defects such as holes and cracks on the surface and side of the specimens, and W-25Re alloy formability is good. With the increase of Ev, the grain morphology in the vertical plane of W-25Re alloy specimens gradually changes from the mixture of equiaxed and columnar grains to coarse columnar grains. W-25Re alloy specimens only contain the cubic W13Re7 phase, and the change in the leftward shift of the diffraction peak 2θ angle is mainly caused by residual stress during the forming process. The influence of laser power and scanning speed on the relative densityof W-25Re alloy is significant. When Ev is 1050 J/mm3, that is, the laser power is 210 W and the scanning speed is 200 mm/s, the W-25Re alloy specimen with a relative density of up to 98.49% can be obtained. At this time, the microhardness of the specimen in the horizontal and the vertical plane is as high as 525.9 HV0.2 and 520.6 HV0.2, respectively, which is close to the hardness value of the rolled W-25Re alloy.

    • Zhencen Zhu, Xiaoqiang Li, Cunliang Pan, Shengguan Qu

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240089

      Abstract:This article refers to the composition of MA754 alloy and prepared Ni-based alloy powders with high melting point containing Ti and Nb as framework, as well as low melting point Ni-based alloy powders with B and Zr as wetting agents by high-energy ball milling, respectively. A Ni-based ODS alloy with excellent performance was prepared by the way of spark plasma sintering after mixing two kinds of powder in the optimal ratio. The influence of sintering temperature and the content of low melting point powder in composite powder on the microstructure and mechanical properties of the alloy was studied. The results showed that dispersed oxides could be observed in the alloy structure prepared by this method, and the mechanical properties were improved compared to MA754 alloy. As the content of low melting point alloy in the composite powder increases, the alloy structure first becomes small and uniform, then acicular aggregate phases and coarse block phases appear. The tensile strength of the alloy shows a trend of first increasing and then decreasing. When the sintering temperature is 1025 ℃ and the content of low melting point alloy powder in the composite powder is 3 wt.%, the alloy has the highest tensile strength of 951.87 MPa, which is significantly improved compared to commercial MA754 alloy.

    • Sun Yetao, Feng Jietao, Yin Jiaxin, Wang Rong, Wang Deqing, Li Chengjun, Wang Yingmin, Fang Canfeng

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240098

      Abstract:In order to investigate the effect of Be on the transformation of Fe-containing phases during solution treatment, a series of experiments combining Be with different solution treatment processes were designed, and the intrinsic relationship between its effect on the morphology of eutectic silicon and Fe-containing phases and the mechanical properties was deeply studied, aiming to comprehensively improve the overall performance of the hypoeutectic Al-Si-Mg alloy. The results showed that Be delayed the decomposition of Mg2Si phase and promoted the transformation of π-AlSiMgFe phase to β-AlFeSi phase. The accelerated transformation of the morphology of the π-AlSiMgFe phase structure not only enhanced the strengthening effect, but also weakened the cleavage effect of the π-AlSiMgFe phase on the matrix, thus synchronously improving the strength and plasticity of the alloy.

    • Yu Lei, Cao Rui, Ma Jin Yuan, Yan Ying Jie, Dong Hao, Wang Cai Qin

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240100

      Abstract:The interface microstructure, micro-hardness, and tensile properties of hot isostatic pressing (HIP) densified Inconel 690 cladding on low alloy steel were investigated during the 600℃-aging process. The interface region can be divided into four zones - carbon-depleted zone (CDZ), partial melting zone (PMZ), planar growth zone (PGZ), and brownish feature zone (BFZ) - from base metal to deposited metal. Dimensions of these zones do not significantly change during aging. However, type Ⅰ carbides noticeably increase in size in the PMZ, and precipitates clearly occur in the PGZ. The main reason for their growth and occurrence is continuous carbon migration. Micro-hardness of the interface shows that the highest hardness appears in the PGZ and BFZ region, which is related to carbon accumulation and precipitates in this region. Tensile failure occurs on the base metal side due to the high strength mismatch between these two materials and is located at the boundary of CDZ and base metal due to the lower strength of only ferrite. The ultimate tensile strength decreases by only 50 MPa after aging for 1500 h, and the interface region maintains high strength with no significant deformation.

    • SUN Yuling, LIANG Hanliang, ZHU Jiansheng, MA Honghao, WANG Luqing, ZHANG Bingyuan, LUO Ning, SHEN Zhaowu

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240103

      Abstract:In this paper, explosion welding is carried out on the basis of vacuum hot melt W/CuCrZr composite plate. Metallurgical microscopy, scanning electron microscopy (SEM) analysis and energy dispersive X-ray spectroscopy (EDS) analysis were used to observe the microscopic morphology of the bonding interface. At the same time, combined with finite element calculations, the evolution mechanism of the interface of the hot melt explosion W/CuCrZr composite plate was explored. The results show that the interface bonding of the hot-melt explosion welded W/CuCrZr composite plate is good,with 3~8μm cross-melting zone, but cracks developed on the W side; The numerical simulation reproduces the changes of combined interface pressure, stress, strain and internal energy in the process of hot melt explosion welding. The location of the crack generated by the experiment coincides with the high stress position calculated by numerical simulation.The high pressure and high temperature near the hot-melt explosion welding interface further promote the bonding of the interface.

    • Huang Wei, Li Jun, Liu Ying

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240104

      Abstract:Using high-purity tungsten powder and amorphous boron powder as raw materials, high-purity W2B alloy powder was efficiently synthesized at low temperatures by mechanical activation and combination reactions. The effects of mechanical activation time on the morphology, particle size distribution, and specific surface area of the powders were investigated, and the relationship between phase composition, synthesis temperature, and reaction mechanism was elucidated. The results indicated that mechanical activation could effectively refine the particles, and the surface area and dislocation density of the powder increased as the mechanical activation time lengthened. The content of the W2B phase in the reaction-synthesized powder increased as the mechanical activation time increased. After 20 hours of mechanical activation, the true density of the reaction-synthesized powder reached 17.01 g/cm3, with the W2B phase content of 96 wt%. The powder synthesized by thatcontained 23 wt% more W2B phase compared to the powder without the mechanical activation reaction. During the synthesis reaction, the B atoms diffused into the W matrix, resulting in the formation of the low-density WB phase. Mechanical activation introduced a significant number of dislocation defects, which created a channel for atoms diffusion and accelerated the transformation of the WB phase to the W2B phase.

    • Luo Jiajun, Quan Ciwang, Zhang Jianjun, Chen Shuixiang, Zhang Xitong, Hang Mengyao, Liang Bingliang, Chen Weihua

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240105

      Abstract:In this paper, core-shell MoSi2@Nb powder was successfully prepared by electrostatic layer self-assembly method. Zeta potential of the suspension were tested by Zeta potentiometer. SEM, TEM and EDS were used to characterize the phase, morphology, structure and element distribution of synthetic materials. The results showed that when the SDS concentration was 2mmol/L, the CTAB concentration was 3mmol/L and the pH value of Nb suspension was 5, the coating effect was better after secondary cladding. NbSi2 phase was found at the interface between Nb and MoSi2 after calcination at 200℃ for 2h in Ar atmosphere under HRTEM and XRD analysis, indicating that Nb is highly active and reacts with Si. Then, the fact that core-shell structure was still retained in MoSi2@Nb material after SPS at 1450℃ for 2h with uniaxial pressure 40Mpa under the SEM and EDS analysis. However, XRD results shown that Nb reacted strongly with MoSi2, and most of the Nb phase was reacted. This issue needs to be addressed in subsequent studies. But, compared MoSi2 material (KIC=3.32 MPa?m0.5), the fracture toughness of MoSi2@Nb material has been significantly improved to 5.75 MPa?m0.5.

    • Zhang Jun, Liu Xi, Li Yi, Chang Guo, Peng Haoran, Zhang Shuang, Huang Qi, Zhao Xueni, Li Liang, Huo Wangtu

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240107

      Abstract:High-strength Cu/Al2O3 composites usually exhibit obviously deteriorated electrical conductivity when compared with their low-strength counterparts. In this work, a chemical and mechanical alloying-based strategy was adopted to fabricate an ultrafine composite powder with low-content reinforcement and construct a combined structure of Cu ultrafine powders covered with in-situ Al2O3 nanoparticles. After consolidation at a relatively lower sintering temperature of 550 ℃, high-volume-fraction ultrafine grains were introduced into the Cu/Al2O3 composite, and many in-situ Al2O3 nanoparticles with an average size of 11.7±7.5 nm were dispersed homogeneously in the Cu grain interior. As a result, the composite showed an excellent combination of high tensile strength (654±1 MPa) and high electrical conductivity (84.5±0.1% IACS), which was ascribed to the synergistic strengthening effect of ultrafine grains, dislocations and in-situ Al2O3 nanoparticles. This approach using ultrafine composite powder with low-content reinforcement as a precursor followed by low-temperature and high-pressure sintering may have the potential to be applied to large-scale industrial production of high-performance oxide dispersion strengthened alloys.

    • lijuan, liuchang, wanglu, lidongting, zhouliyu, liuying

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240108

      Abstract:In order to improve the hardness and wear resistance of titanium (Ti), in this paper, it is proposed to introduce TiB2 hard phase into pure titanium (Ti), accurately control the reaction process of the two based on the discharge plasma sintering (SPS) technology, and construct a TiB2-TiB-Ti "hard-core-strong-interface" structure in Ti matrix that inherits the diffusion path of B elements. Finally, at 40% TiB2 addition, a high hardness of 863.5 HV5 at room temperature and 720.9 HV5 at 400℃ in the middle and high temperatures is obtained, which makes its friction performance better than that of commercial TC4 high-temperature titanium alloys under the same friction conditions in the temperature range from room temperature to 400℃. At the same time, thanks to its excellent bonding interface, the alloy also exhibits unique high-temperature and high-toughness properties, maintaining a high compressive strength of 1120 MPa and compression of more than 10% at 400℃. The design concept of this study is inspirational and useful. The design idea of this study is inspiring and universal, which is expected to provide a new method for the research and development of new medium-high-temperature and high-toughness wear-resistant titanium alloys, and to promote the application of related materials in aerospace field.

    • Xuan Wan, Chaowei He, Kezhao Zhang, Dong Liu, Chunyan Yan, Yefeng Bao

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240109

      Abstract:Laser beam welding was used to join a near-β titanium alloy (Ti-3Al-6Mo-2Fe-2Zr), and afterwards, aging treatment at different temperatures were conducted on the laser welded joints. The relations among aging temperature, microstructure, and tensile properties of joints were revealed in detail. For as-welded joints, the fusion zone features primarily single β phase. The reason is attributed to the high Mo equivalency of this alloy and the fast cooling rate in laser beam welding. After aging treatments, a large amount of α precipitates forms in the fusion zone and HAZ. The rising aging temperature coarsens α precipitates and reduces the volume fraction. Compared with the as-welded joints, the joints’ tensile strength and elongation are improved after undergoing aging treatments. The increasing aging temperature weakens the strengthening effect because of the decreasing volume fraction of α precipitates. After the 500°C/8h aging treatment, the joints obtain the optimal match between strength and plasticity. The fracture mode of joints changes from quasi-cleavage fracture in as-welded condition to microvoid coalescence fracture after heat treatments.

    • 宋博, Honglei Xi, Yu Fu, Junshuai Wang, Wenlong Xiao, Yanbiao Ren, Chaoli Ma, Lian Zhou

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240111

      Abstract:The influence of pre-strain on phase transformations, microstructures and hardening response in near β Ti alloy Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe (wt.%) during aging treatment is studied in this work. The results showed that obvious α phase refinement and stronger age hardening effect can be achieved when slightly deformed before aging treatment. Because the intermediate phases (O′, ω and O′′) formation suppressed long-range stress induced martensitic transformation and mechanical twinning, the samples were mainly deformed via dislocations slipping during loading. Numbers of crystal defects were generated during pre-deformation. With the pre-strain increasing, the number density of dislocations increased gradually. These crystal defects generated by pre-deformation would partly annihilate upon early aging, but the precipitation of α was also be promoted and resulted in refined α precipitates. In the sample pre-strained to 5 %, the average thickness of α precipitates was decreased by 57 % during aging at 600 oC than the unstrained sample, and the number density was increased from 7.0±1 laths/μm2 to 22.0±3 laths/μm2. Some platelet-shaped α were formed when the samples experienced comparably large pre-strains, i.e. 12 % and 20 %. It proved clearly that the refined α precipitates and higher hardening effect could be obtained by pre-deformation plus aging treatment in titanium alloy.

    • Wang Chunhui, Yang Guangyu, Qin He, Kan Zhiyong

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240112

      Abstract:The I phase (Mg3GdZn6, icosahedral quasicrystal phase) is widely considered as the strengthening phase in Mg-Zn-Gd system alloys, offering more significant improvements in the mechanical properties compared to the W phase (Mg3Gd2Zn3, cubic phase). However, both the W phase and the I phase typically coexist in the as-cast Mg-Zn-Gd alloy, thereby weakening its mechanical properties. There has been limited systematic research dedicated to investigating the crystallization mechanism of these phases during solidification. In this study, the equilibrium solidification and Scheil solidification paths of Mg-xZn-2Gd (x = 0~12, wt.%) alloys were calculated using Thermo-Calc software. The effects of cooling rate and alloy composition on the fraction of the I phase were studied. The results show that the equilibrium solidification structure of the alloy with a Zn/Gd atomic ratio of 6.0 only contains the I phase. In contrast, limited solute diffusion in the solid phase hampers the transformation of the W phase into the I phase during non-equilibrium solidification, forming a mixed structure composed of both the W phase and the I phase. The variation of cooling rate and alloy composition affects the solute enrichment rate in the Liquid during the solidification process of the primary α-Mg phase, alters the solute content and temperature of the residual Liquid when the secondary phase begins to crystallize, and influences the type and fraction of the secondary phase as determined by the solidification driving force. Higher solidification cooling rates and an increased Zn/Gd atomic ratio inhibit the W phase and promote the formation of the I phase during Mg-Zn-Gd alloy preparation, resulting in the alloy with a higher proportion of the I phase.

    • Luan Lijun, Xu Changyan, Zhang Ziqiu, Xie Haichen

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240113

      Abstract:The garnet type CexY3-xFe5O12 doped with Ce3+ was prepared by an optimized sol-gel method (x = 0, 0.1, 0.2, 0.3; Ce:YIG) crystal, the optimal solution is to obtain crystals with no derived impurities and high magneto-optical properties by pre-sintering and sintering in a wide temperature range of 900-1400 ℃. Thermogravimetric analysis was used to determine the synthesis temperature of the crystal at 890 ℃. XRD results show that the crystal lattice constant varies from 12.37241 ? to 12.4121 ?, and the impurity phase CeO2 appears when Ce > 0.2. SEM analysis shows that the grain size of Ce:YIG increases with the increase of sintering temperature and Ce3+ content, and its size distribution ranges from 0.257 to 6.52 mm, which is the maximum size of YIG crystal obtained at present. All Ce: YIG samples were ferromagnetic at room temperature, with saturation magnetization varying from 23.47 to 28.10 emu/g. The permeability of Ce0.1Y2.9Fe5O12 crystal sintered at 1200 ~1300 ℃ is as high as 3.68 ~ 3.90. According to the relationship between Faraday rotation Angle and permeability, the crystal sintered in this temperature range is likely to obtain the best Faraday rotation performance.

    • CHEN Jianbo, YANG Xiaojiao, YANG Ningjia, NIU Yibo, OUYANG Linfeng, Ying Liu

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240114

      Abstract:Kilogram-scale micro-nano SrVO3 powder was produced with the sol-gel method combined with hydrogen reduction and heat treatment. Then SrVO3 bulks were prepared by cold pressing and sintering the sifted powders using different mesh sizes (unsifted powder, 100 mesh, 200 mesh, and 300 mesh). The thermal stability of SrVO3 powder and bulks under air was investigated, and the effects of powder granularity sifting on granularity and distribution of their raw material, bulk grain size, and electrical conductivity were also evaluated. The results show that: SrVO3 bulk has better thermal stability in air than SrVO3 powder; the temperature at which oxidative weight increase occurs is enhanced from 335 °C for the powder to 430 °C for the bulk. The mean particle size of the raw material powders decreases, the electrical conductivity of the related cold-pressing sintering bulks is significantly raised, and the conductivity of the powders rises with increasing granularity sifting mesh. Granularity sifting can be used to acquire smaller and more uniform powder raw materials, which will increase the density of the bulks produced by cold-pressing sintering. Furthermore, the material’s more effective routes for the conduction of electric charge are established and the conductivity of the prepared SrVO3 bulk reaches 20,000 S/cm, which is 37% higher than that of the bulk produced by unsifted powder. Granularity sifting is essentially the optimization of the raw material’s particle size. More sifting of the SrVO3 powder’s particle size is expected to yield improved bulk material performance, providing the foundation for its use in transparent conductive films, semiconductor devices, sensors, and other areas.

    • Xie Manman, Jia Dongxiao, Jia Xilin, Zhao Fei, Liang Tian, Zhou Yangtao

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240115

      Abstract:In this paper, the microstructure and corrosion behavior of a 1.0 wt.% Gd duplex stainless steel annealed at different temperatures were studied. Electron microscopy revealed that the content of secondary Gd-containing phase was increased along with the increasing annealing temperatures and then decreased at 1080℃ as an inflection point. A dual-phases M-Gd intermetallic with M3Gd as the core phase and M12Gd as the shell was the main type of secondary phase in the sample annealed at 1080℃. In the sample annealed at 1140℃, M3Gd phase was dominant. The corrosion behaviors of the two annealed steel samples were analyzed in NaCl, HCl and H3BO3 solutions. It showed that the sample annealed at 1140℃ had lower corrosion rate. M3Gd was more electrochemically active than M12Gd when the sample was immersed in NaCl and HCl solutions but more noble in H3BO3 solution.

    • Hao Huirong, Wang Jiawei, Zhao Wenchao, Ren Jiangpeng

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240116

      Abstract:The present study uses a predictive model to design a heavy-duty metal rubber (MR) shock absorber used to mount the powertrains of heavy-load mining vehicles. The microstructural characteristics of the wire mesh are elucidated using fractal graphs. A numerical model based on virtual fabrication technology is established to inform a design scheme for the proposed wire mesh component. Four sets of wire mesh shock absorbers with various relative densities are manufactured. A predictive model based on these relative densities is established through mechanical testing. To further enhance the predictive accuracy, a variable transposition fitting method is introduced to refine the model. Residual analysis is employed to quantitatively validate the results against those obtained from an experimental control group. The findings demonstrate that the improved model exhibits higher predictive accuracy than the original model, with the coefficient of determination (R2) reaching 0.9624. This study provides theoretical support for designing wire mesh shock absorbers with reduced testing requirements and enhanced design efficiency.

    • Xu Qinsi, Zhang Mingchuan, Liu Yi, Cai Yusheng, Mu Yiqiang, 任德春, Ji Haibin, Lei Jiafeng

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240118

      Abstract:The "bond line" of the diffusion bonding interface is a common characteristic of the diffusion-bonded region in nickel-based superalloys. It significantly impacts the performance of the diffusion joint. Thermal deformation machining is an effective method to improve the microstructure and properties of a diffusion bonding interface. In this study, the thermal deformation behavior of the GH4169 alloy diffusion-bonded region was investigated at a deformation temperature of 1213~1333 K with a strain rate of 0.01~10 s-1 using a Gleeble 3800 thermal-mechanical simulation test machine. The results show that the "bond line" in the diffusion bonding region of GH4169 alloy can be effectively eliminated through thermal deformation. The evolution of the δ phase in the diffusion bonding interface region is affected by deformation conditions. When the deformation temperature is lower than the solution temperature of the δ phase, the residual spheroidized δ phase prevents the growth of recrystallization nucleation grains and affects the subsequent recrystallization process. The spheroidization degree of the δ phase can be enhanced by reducing the strain rate. When the deformation temperature exceeds the dissolution temperature of the δ phase, the dissolution of the δ phase creates an extra driving force for recrystallization, thereby significantly enhancing the extent of recrystallization. A hyperbolic sinusoidal Arrhenius constitutive equation, incorporating strain compensation, is used to describe the correlation between flow stress and deformation conditions in the diffusion-bonded region of the GH4169 alloy. The calculated values of the constitutive equation agree with the experimental values. According to the dynamic model of the GH4169 alloy diffusion bonded region, the optimal processing parameters have been determined. The deformation temperature is 1310~1333 K, and the strain rate is 0.01~0.05 s-1.

    • Yu Zhiqi, liu Tianzeng, Zhao Yanchun, Feng Li, Li Jucang, Pan Jixiang

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240122

      Abstract:In this paper, the static corrosion experiment of 347H stainless steel alloyed with Cu and Mo elements was carried out in nitrate (60 % NaNO3+40 % KNO3) at 565 °C for 720 h. The effects of Cu and Mo elements on the corrosion resistance of 347H stainless steel in molten salt were studied by analyzing the phase composition, microstructure and chemical composition of the corrosion products. The results show that the grain refinement of Mo element makes the stainless steel have the best corrosion resistance of medium grain size. Furthermore, the formation of MoC contributes significantly to enhancing the intergranular corrosion resistance of the stainless steel. The stainless steel exhibited uniform corrosion in the nitrate solution. The corrosion layer displayed a dual-layer structure, with corrosion products of the protective matrix present in both the inner and outer layers. The outer layer comprised a mix of Fe oxide (Fe2O3, Fe3O4), NaFeO2, and a minor portion of MgFe2O4. Conversely, the inner layer primarily consisted of a spinel layer (FeCr2O4, MgCr2O4) and a thin Cu2O layer. The oxidation of Cu in the inner layer led to the development of a dense Cu2O layer, effectively impeding O2- plasma infiltration into the matrix.

    • lujianqiang, wanglinlin, oumeiqiong, houkunlei, wangmin, wangping, mayingche

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240125

      Abstract:As the thrust-to-weight ratio of the aero-engine increases, the turbine inlet temperature increases significantly, leading to a significant increase in the service temperature of other key hot-end components. In the process of service, nickel-based superalloys need to withstand the combined effect of high temperature, stress and environment, and the alloy surface will inevitably occur high temperature oxidation. High temperature oxidation often preferentially penetrates along grain boundaries, resulting in micro-voids and micro-cracks at grain boundaries, which seriously affects the properties of the alloy. Therefore, it is necessary to explore ways to improve the oxidation resistance of alloys at high temperatures. In this work, the effect of Hf on oxidation behavior of K4800 nickel-based superalloy was studied. The results show that the oxidation weight gain of K4800 and K4800+0.25Hf alloys increases with the extension of exposure time during static oxidation at 800℃ and 850℃, and the oxidation kinetics curves follow the parabola rule. However, the initial static oxidation rate of K4800+0.25Hf alloy (0.0265 g/m2·h at 800°C for 20 h and 0.0617 g/m2·h at 850°C for 20h) is lower than that of K4800 alloy (0.041 g/m2·h at 800°C and 0.0669 g/m2·h at 850°C). The oxide layer of the two experimental alloys comprises an outer oxide layer and an inner oxide layer.The outer oxide layer primarily consists of dense Cr2O3, while the inner oxide layer mainly contains dendritic Al2O3. However, with the Hf content increasing from 0 wt.% to 0.25 wt.%, the thickness of the Cr2O3 outer oxide layer decreases from 2.71 μm to 2.17 μm after oxidation at 800°C for 1000 h and from 5.83 μm to 4.09 μm after oxidation at 850°C for 1000 h.The results of EPMA analysis indicate the formation of HfO2 at the grain boundary of the oxide layer in the K4800+0.25Hf alloy, promoting the formation of Al2O3 around HfO2 and accelerating the growth of Al2O3. The presence of Al2O3 and HfO2 at the grain boundary contributes to reducing the outward diffusion rate of Cr3+ and delaying the thickening of the Cr2O3 oxide layer. Consequently, the addition of Hf enhances the oxidation resistance of the K4800 alloy.

    • Guo Peimin, Shen Yaozong, Wang Lei, Kong Ling-bing, WANG Dond-xin, GUO Qing

      Available online:June 26, 2024  DOI: 10.12442/j.issn.1002-185X.20240130

      Abstract:Modern methods of beryllium metallurgy are based on the theory of sulfuric acid dissociation and chemical purification. Since the high solubility of sulfate produced by sulfuric acid dissociation and the overlap of the condition interval of the chemical method of separation resulted in low purity of the beryllium product and the presence of Be2+ in the separated phase, which would form a hazardous waste and reduce the yielding rate of beryllium. A transformative beryllium metallurgy theory and methodology based on the low-temperature dissociation of hydrofluoric acid and purification by exploiting the large difference of fluoride solubility is proposed. Hydrofluoric acid can quickly dissociate beryllium ore powder directly at low temperature or room temperature with a dissociation rate of more than 99%. The solubility of AlF3, FeF3, CrF3 and MgF2 is low. Coupled with the presence of common ion effect, 99.9% beryllium products can be prepared without chemical purification. For high-purity beryllium products of grade 4N or higher, high-purity beryllium can be prepared by utilizing the superior property that the pH intervals of iron, chromium, and other hydroxide precipitates are distinctly different from the pH intervals corresponding to Be(OH)2 precipitates. The new method covers a wide range of beryllium products that can be prepared by modern beryllium metallurgy.

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    Latest number
    Rare Metal Materials and Engineering
    2024,Volume 53, Issue 6
    Editor in chiefPingxiang Zhang
    Associate editorYingjiang Shi
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