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Effect of Compression Passes on Mechanical Properties and Corrosion Behavior of ZK60 Magnesium Alloy
Yin Dongsong, Liu Zhiyuan, Zhang Youyou, Mao Yong, Han Tianming
2024,53(12):3338-3347 DOI: 10.12442/j.issn.1002-185X.20240102
Abstract:The impact of multi-directional compression passes on the microstructure, mechanical properties, and corrosion behavior of ZK60 magnesium alloy was investigated. Results reveal that severe dendrite segregation exists in the as-cast ZK60 magnesium alloy with coarse MgZn phases distributed along the grain boundaries. After 9 passes of compression, the coarse solidified phases at the grain boundary are significantly refined, and back dissolution occurs. Fine recrystallized grains accompanied with the fine diffused nano-phases emerge in the local area around the large grains. The tensile strength of ZK60 magnesium alloy generally exhibits the upward trend with the increase in compression passes, whereas the compression rate shows the downward trend. The compressive strength reaches 433.6 MPa with the compression rate of 21.3% after 9 passes of compression. Multi-directional compression can significantly reduce the degradation rate of ZK60 magnesium alloy in simulated body fluids. Furthermore, it is observed that in the as-cast ZK60 magnesium alloy, micro-segregation can easily lead to severe intragranular local corrosion. However, after multi-directional compression, the tendency to intragranular local corrosion is significantly diminished.
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Liu Na, Zhao Zhanglong, Liu Yuli, Feng Kaikai, Zha Xiaohui, Li Pu, Xu Wenxin, Yang Haiou, Lai Yunjin
2024,53(12):3281-3290 DOI: 10.12442/j.issn.1002-185X.20240097
Abstract:Near-α titanium alloy and Ti2AlNb alloy powders premixed with different proportions were prepared on the near-α titanium alloy substrate by laser deposition technique, and the microstructure characteristics were analyzed and discussed. Results show that numerous river-like sub-grain structures are formed inside the equiaxed B2 grains of the laser-deposited premixed titanium alloy powders with the proportion of Ti2AlNb above 40wt%, whereas the needle-like structure within coarse columnar β grains exist with the proportion of Ti2AlNb below 40wt%. It is noteworthy that the decrease in laser power and scanning speed can accelerate the formation of sub-grain structures. Based on the analysis of experimental results, it can be inferred that the formation of sub-grain structure not only is related to the precipitation of O phase due to composition micro-segregation at sub-grain boundaries, but also is inseparable from the stacking faults caused by the internal stress during the laser deposition.
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Liu Hang, Yang Chaoyun, Zhang Yao, Luan Yikun, Li Dianzhong
2024,53(12):3291-3298 DOI: 10.12442/j.issn.1002-185X.20240023
Abstract:A 2D transient mathematical model was established to separately describe the anode bubble dynamics and the bubble-induced electrolyte motion in the rare earth electrolysis cell with horizontal electrode. Results indicate that with the increase in the anode inclined angle, the maximum bubble thickness is increased gradually. Furthermore, compared with the conventional anode, the inclined and chamfered anodes are conductive to the bubble length reduction and the bubble velocity improvement. Meanwhile, the bubble-induced electrolyte motion in the electrolysis cell can improve the distribution and transport process of oxyfluorides, thereby enhancing the current efficiency. Finally, a novel feeding method based on the electrolyte flow is proposed.
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Hao Juan, Wang Baichuan, Ding Yuhang, Yang Chao, Jiang Bailing, Wang Ziyi, Wang Donghong, Dong Dan
2024,53(12):3299-3305 DOI: 10.12442/j.issn.1002-185X.20240043
Abstract:TiN coatings were prepared by the novel dual-stage high power impulse magnetron sputtering (HIPIMS) technique under different deposition time conditions, and the effects of microstructure and stress state at different coating growth stages on the mechanical, tribological, and corrosion resistance performance of the coatings were analyzed. Results show that with the prolongation of deposition time from 30 min to 120 min, the surface structure of TiN coating exhibits a round cell structure with tightly doped small and large particles, maintaining the atomic stacking thickening mechanism of deposition-crystallization-growth. When the deposition time increases from 90 min to 120 min, the coating thickness increases from 3884 nm to 4456 nm, and the stress state of coating undergoes the compression-tension transition. When the deposition time is 90 min, TiN coating structure is dense and suffers relatively small compressive stress of -0.54 GPa. The coating has high hardness and elastic modulus, which are 27.5 and 340.2 GPa, respectively. Meanwhile, good tribological properties (average friction coefficient of 0.52, minimum wear rate of 1.68×10-4 g/s) and fine corrosion resistance properties (minimum corrosion current density of 1.0632×10-8 A·cm-2, minimum corrosion rate of 5.5226×10-5 mm·A-1) can also be obtained for the coatings.
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Xue Jianchao, Jia Bo, Wang Yafei, Feng Qing, Chai Zuoqiang, Hao Xiaojun, Xue Juanqin
2024,53(12):3306-3312 DOI: 10.12442/j.issn.1002-185X.20240067
Abstract:Alumina coatings doped with different precious metals were prepared by cathode plasma electrolytic deposition. Results show that the porosity of precious metal-doped alumina coatings (especially Al2O3-Ru) decreases, and the high-temperature cyclic oxidation resistance and spallation resistance are enhanced. The Al2O3-Ru composite coating shows better effect: its average oxidation rate K and average amount of oxide spallation G are minimum. Meanwhile, Nernst equation was used to explain the simultaneous deposition of precious metal and alumina, and the whole process and mechanism of deposition were analyzed.
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Ji Jinjin, Jia Zhi, Yang Peiyao, Wang Yanjiang, Kou Shengzhong
2024,53(12):3313-3320 DOI: 10.12442/j.issn.1002-185X.20240091
Abstract:The microstructure and mechanical properties of Inconel 617 alloy rolled at room temperature with different deformation degrees (20%, 50%, 70%) were investigated. The grain refinement mechanism and main texture types of Inconel 617 alloy during rolling were analyzed via electron backscatter diffraction and X-ray diffraction, and the microhardness and tensile properties of Inconel 617 alloy with different deformation degrees were tested. Results reveal that the grains of Inconel 617 alloy are refined during the rolling deformation process, and the refinement mechanism is the fragmentation of original grains caused by the increase in dis-location density and strain gradient. The main microtextures of the rolled samples are Goss {011}<001>, Rotated Goss {110}<110>, Brass {011}<211>, and P {011}<112> textures, and their intensity is increased with increase in deformation degree. After rolling deformation, the strength of the Inconel 617 alloy is improved and the ductility is reduced by the combined effect of grain refinement and dislocation strengthening. Comprehensively, the yield strength and elongation of Inconel 617 alloy after 20% deformation are 772.48 MPa and 0.1962, respectively, presenting good synergy effect.
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Liu Peng, Guo Xuan, Gao Dongfang, Zhao Yangyang, Qiao Yang
2024,53(12):3321-3328 DOI: 10.12442/j.issn.1002-185X.20240249
Abstract:The surface of magnesium alloy was laser-processed, and the laser-etched morphology was determined as grooves by observing the surface morphology of sheep rib bone. The wettability of different morphologies was investigated by contact angle test. Through the cell adhesion test, the effects of different morphologies on cell adhesion, growth and migration were investigated. Results show that the wetting angle of the block-shaped surface is smaller than that of the groove-shaped surface, and block-shaped surface has better hydrophilicity. Compared with the smooth surface, the block-shaped surface has better cell adhesion, and the depressions and bumps are full of cells, suggesting that the micropatterns prepared by the laser processing are conducive to the enhancement of biocompatibility.
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Wang Yupeng, Li Siying, Ma Tengfei, Wang Xiaohong, Dong Duo, Zhu Dongdong
2024,53(12):3329-3337 DOI: 10.12442/j.issn.1002-185X.20240001
Abstract:TiAl alloy was mixed with BN nanoplates and then sintered at 1300 °C through spark plasma sintering technique, and the hybrid TiB2-Ti2AlN/TiAl composites were in-situ prepared. The microstructural evolution and mechanical properties at room temperature of TiAl composites were investigated. Results show that a fully lamellar microstructure can be achieved in the TiAl composites with BN nanoplates of lower content, whereas a transformation to the nearly lamellar microstructure can be observed under higher BN nanoplate content conditions. The microstructure of TiAl composites is significantly refined due to the even distribution of in-situ prepared TiB2-Ti2AlN particles at the lamellar colony boundaries. Notably, a continuous core-shell structure of TiB2-Ti2AlN particles is formed at the lamellar grain boundary after adding 0.5wt% BN nanoplates. The results of compression and friction wear at room temperature show that the hardness and compressive strength of TiAl composites are greatly improved with the increase in BN nanoplate content from 0wt% to 1wt%. Meanwhile, the average coefficient of friction decreases from 0.59 to 0.47, and the wear rate decreases by 29.9%. These remarkable mechanical properties are mainly attributed to the strengthening effects of the in-situ formation of TiB2-Ti2AlN particles, refined microstructure, and core-shell structure.
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Wang Youliang, Kang Yating, Zhang Wenjuan, Jiang Zhe, Yin Xincheng
2024,53(12):3348-3357 DOI: 10.12442/j.issn.1002-185X.20240011
Abstract:Preparation method of magnetic nanoparticles with core-shell structure was introduced, especially focusing on the preparation principle of sol-gel method, microemulsion method, and self-assembly technique. The application of core-shell nanoparticles in precision machining was discussed. The Fe3O4@SiO2 composite particles were prepared by sol-gel method and were applied to the magnetorheological polishing of titanium alloy plates. Results show that core-shell nanoparticles with higher surface quality can be obtained after processing, compared with those after conventional abrasives. After polishing for 20 min, the surface roughness of the workpiece reaches 23 nm and the scratches are effectively reduced. Finally, the preparation and application of core-shell nanoparticles are summarized and prospected to provide a reference for further research on core-shell nanoparticles.
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Xiu Lei, Gu Haozhong, Lv Anna, Hong Ronghui, Zhang Zhirong
2024,53(12):3358-3372 DOI: 10.12442/j.issn.1002-185X.20240059
Abstract:Semi-solid processing (SSP) technique is an important method for metal casting. Products made by SSP technique have advantages such as small solidification shrinkage, high dimensional accuracy of castings, fast forming speed, high productivity, and good mechanical properties. Aluminum alloy products produced by SSP technique can be heat-treated. The mechanical properties of the products after heat treatment are similar to those of steel, but they have the lighter mass and are widely used in many fields. Semi-solid slurry preparation technique is one of the key techniques in the field of aluminum alloy semi-solid forming, which determines the industrial application of semi-solid forming and also has significant impact on the quality of aluminum alloy semi-solid slurry. Semi-solid slurry preparation technique with the continuous development has become the emerging technique in the field of metal processing. The principles, advantages and disadvantages of various semi-solid slurry preparation techniques for metal materials were reviewed, and the future trends of semi-solid slurry preparation techniques were predicted.
2024,Volume 53, Issue 12
>ARTICLE
>REVIEW
- Published Issue
- Call for Papers
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Zhao Lun, Sun Zhichao, Wang Chang, Zhang Pengsheng, Tang Shuai, Zhang Baoxin
Available online:December 02, 2024 DOI: 10.12442/j.issn.1002-185X.20240618
Abstract:Four types of Mg-5Zn porous scaffolds with different pore geometries, including body-centered cubic (BCC), rhombic dodecahedron (RD), primitive (P), and gyroid (G), were designed and fabricated using SLM. Their forming quality, compression mechanical properties, and degradation behavior were investigated. The results indicate the scaffolds fabricated exhibited good dimensional accuracy, and the surface chemical polishing significantly improved the surface quality while reducing forming errors. Compared to the rod structures (BCC, RD), the surface structures (G, P) scaffolds had less powder particle adhesion. For the same design porosity, the G porous scaffold exhibited the best forming quality. The predominant failure mode of scaffolds during compression was a 45° shear fracture. At a porosity of 75%, the compression performance of all scaffolds met the compressive performance requirements of cancellous bone, and BCC and G structures showed relatively better compression performance. Immersed in Hank"s solution for 168 hours, the B-2-75% pore structure scaffold exhibited severe localized corrosion, with fractures in partial pillar connections. In contrast, the G-3-75% pore structure scaffold mainly underwent uniform corrosion, maintaining structural integrity, and the corrosion rate and loss of compressive properties are less than those of the B-2-75% structure. After comparison, the G-pore structure scaffold is preferred.
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Xuyan Guo, Zhuangzhuang Xiong, Guixiang Wang, Qiang Zhou, Yanxiong Wu, Delong Kong, Fuqiu Ma, Ruizhi Wu
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240460
Abstract:This article investigates a straightforward, highly effective, and eco-friendly technique for preserving carbon steel surfaces against corrosion, by depositing Cu-Ni alloy coatings on the workpiece"s surface to impede corrosive medium. The effects of current density and Cu2+ concentration on the composition, morphology, and composition of the coating were investigated using scanning electron microscopy, X-ray energy dispersive spectroscopy, Vickers hardness tester, friction and wear tester, and electrochemical testing. A cauliflower like Ni rich protrusion structure appears on the coating surface. The lower current density and Cu2+ concentration affect the Vickers hardness and wear resistance of the coating by affecting the grain microstructure and Cu/Ni content, both leading a decrease in hardness and wear resistance. When the current density is 10 mA/cm2 and the Cu2+ concentration is 0.1 mol/L, the corrosion current density of the deposited sample reached 1.389×10?5 A·cm?2, and its surface corrosion damage was significantly less than that of the sample without coating after 24 h of salt spray test. Research on the deposition mechanism indicates that Cu2+ undergoes instantaneous nucleation under diffusion control, tending towards vertical growth and forming cauliflower-like protrusions, while Ni2+ is controlled by electrochemistry to discharge uniformly across the surface.
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Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240464
Abstract:The bending springback of magnesium alloys is difficult to predict accurately in numerical simulations because of its anisotropic characteristics. The springback of magnesium alloys in v-shaped roll bending was analyzed more accurately using the error optimization function in Matlab to optimize the anisotropic potential values required for the Hill’48 yield criterion in ABAQUS. The optimized Hill’48 yield criterion model was used to numerically simulate the springback of magnesium alloy v-shaped roll bending. The simulation results were compared with the experimental results. The error between the springback change ratio obtained using the optimized Hill’48 yield criterion and experimentally formed parts was within 2%. Overall, the optimized Hill’48 yield criterion model can improve the springback prediction accuracy of magnesium alloy v-shaped roll forming.
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Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240470
Abstract:The microstructure of Ti-6Al-4V joints by hollow cathode vacuum arc welding with different gas flow rate was studied, and the tensile properties were investigated. The results show that the microstructure of base metal was mixture of α phase β phase. The microstructure of heat affected zone are equiaxed and primary α and needle martensite α′ dispersed in the transformed β. Two kinds of tissues distribution depends on the heat-affected area affected by the welding thermal cycle.The microstructure of welding seam consists mainly of α′ martensite phase. Reduce welding gas flow rate and increase welding energy density, resulting in coarsening and more scattered distribution of martensitic grains. The tensile strength of welded joint is higher than that of base metal.
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mengshuaiju, songjinlong, chenkeyi, cuimin, wanglidong, biguangli, caochi, yangguirong
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240480
Abstract:Low-temperature equal channel angular pressing (ECAP) processing technology has great potential in fabricating bimodal-grained alloys composed of ultrafine grains and fine grains. Besides, fine grain Mg-Bi based alloys demonstrate excellent low temperature plastic deformation performance. Based on this, a new inverse temperature field ECAP (ITF-ECAP) processing method was developed to realize the severe plastic processing of a fine grained Mg-6Bi (B6) alloy at low temperature (<100 ℃) to construct a bimodal-grained microstructure composed of ultrafine (<1 μm) and fine grains (1-10 μm). The microstructure and mechanical properties characterization results show that dynamic recrystallization preferentially occurred at the initial grain boundaries of the fine-grained B6 alloy during the multi pass ITF-ECAP processing. Besides a large amount of submicron sized Mg3Bi2 phase precipitated during ITF-ECAP processing. As a result, bimodal-grained microstructure consisting of ultrafine grains with an average grain size (AGS) of about 600 nm and fine grain region with an AGS of about 2 μm was successfully constructed in B6 alloy through 4-pass ITF-ECAP processing. The volume fraction of the ultrafine grain region accounts for about 72.5 %. Due to the combined effects of grain-boundary strengthening, precipitation strengthening, dislocation strengthening, and back stress strengthening, the bimodal-grained B6 alloy exhibits excellent strength and ductility, with yield strength and elongation reaching 315.6±3.6 MPa and 22.3±1.0 %, respectively.
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Xu Yaxin, Zou Han, Huang Chunjie, Li Wenya
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240483
Abstract:Cold spraying has great advantages in preparation of oxidization-sensitive metallic coatings because of the lower heat input and almost no oxidation resulting from its low temperature process. Combined with the convenience of cold spraying in manufacturing particle reinforced composite coatings, titanium matrix composite coatings prepared by cold spraying can compensate for the shortcomings of poor wear resistance of pure titanium or titanium alloys. In addition, one can also get the functional coatings besides the structural coatings. According to the existing research reports, the deposition behaviors and mechanisms of cold-sprayed titanium matrix composite coatings were summarized. By analyzing the porosity and deposition efficiency, the effect of strengthening on the microstructure of the cold-sprayed titanium matrix composite coatings was explained. The mechanism of reinforcement on mechanical and wear performance of titanium matrix composite coatings were revealed. Finally, the future application of cold-sprayed titanium matrix composite coatings is prospected, and several promising directions are listed.
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wuyin, Zhang Hao, Zhu Yuping, Fang Shimin, Ding Yaoyao, Liang Liwen, Yan Guangqiang, Qiu Zixiang, Wang Haixuan, Dongye Shengshua, Tian Miaocheng, Yang Yang, Huang Qizhong, Zheng Yongjian
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240487
Abstract:This study focuses on the SLM (Selective Laser Melting) formed ZGH451 nickel-based superalloy, revealing the mechanism by which solidification liquid films lead to crack initiation and clarifying the roles of alloy elements and texture in forming crack defects. Experimental results indicate that cracks in the SLM process of ZGH451 nickel-based superalloy can be mainly categorized into internal solidification cracks and edge cold cracks. During the late solidification stage, low-melting-point phase liquid films exist between dendrites, and high-melting-point Cr element particles at the solidification front hinder melt feeding. The insufficient feeding and thermal stress between dendrites cause the liquid film"s rupture, leading to solidification cracks in the core of the material. In the alloy"s contour region, high cooling rates and significant thermal stress lead to residual stress accumulation, which exceeds the material"s strength limit or grain boundary cohesion strength, resulting in the formation of cold cracks. When the input laser energy density is below 53.6 J/mm3, pores and lack of fusion defects increase significantly in the alloy, while exceeding 130.9 J/mm3 sharply increases the probability of keyhole formation along the melt pool track. These defects can induce cracks under stress. The more TiC and other carbide particles precipitate between dendrites, the greater grain misorientation, and the higher the alloy"s crack sensitivity. The deposited state of ZGH451 nickel-based superalloy is mainly composed of γ and γ" phases, with a preferred orientation on the (100) plane. The average aspect ratio of the grains reaches 11.25, and the significant texture exacerbates stress concentration at the grain edges and tips, promoting crack initiation and altering crack propagation direction.
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Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240492
Abstract:The effect of different intermediate annealing heat treatments on the surface microstructures and anodic oxide film structures of rolled sheets of an Al-5.6Mg alloy was studied. The results show that when the continuous annealing is used instead of the static state annealing in intermediate annealing process to control microstructures of the sheets, the surface grain size of the sheets can be reduced by about 60 %, and size of the Mg precipitated phase (Mg2Al3) can be reduced by about 67 %. Under the combined influence of grain size, uniform precipitation phase, and texture, the highest glossiness can be obtained, which was attributed to continuous intermediate annealing and stabilization annealing at low temperature. The uniform grain and precipitation structures is beneficial to reduce the inhomogeneous dissolution of the oxide film and to obtain the anodic oxide film with uniform thickness and high gloss.
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Li Qianru, Zhang Fan, Niu Shiyu, Wang ying, Yang Zhenwen
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240495
Abstract:This study systematically investigates the influence of Ni interlayer thickness on the microstructure, mechanical properties, and corrosion resistance of Zr-4/Nb/Ni/316SS diffusion bonded joints. The experimental results reveal that the typical interface microstructure of the joints consists of Zr-4/β-(Zr, Nb)/Nb/Ni3Nb/Ni/316SS. The shear strength of the joints initially increases and subsequently decreases with increasing Ni interlayer thickness, reaching a peak value of 380 MPa at an interlayer thickness of 30 μm. To elucidate the effect of Ni interlayer thickness on the mechanical properties, the microstructural characteristics of the joint interfaces were characterized, and Abaqus simulations were conducted to analyze the residual stress distribution across the interfaces. The comparative analysis of the mechanical properties and fracture behavior, combined with simulation results, indicates that while thicker Ni interlayers are more effective in alleviating residual stress, excessively thick interlayers lead to a reduction in shear strength due to their enhanced ductility. Additionally, the corrosion resistance of the joints was assessed using full immersion corrosion tests. The results indicate that the corrosion rate decreases with a reduction in Ni interlayer thickness, with the optimum corrosion resistance observed at an interlayer thickness of 10 μm. In conclusion, it is recommended that the Ni interlayer thickness be maintained between 10 μm and 30 μm to achieve a balance between mechanical properties and corrosion resistance.
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Nan Lingxin, Qi Yanfei, Xu Pengfei, Li Yungang, Pang Binghe
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240509
Abstract:Superalloy has a very important position in the development of nuclear fusion and other fields, and the use of the requirement is to form a stable and protective oxide under high temperature service conditions, and the oxide can prevent further oxidation of the alloy. In order to study the stability and oxidation resistance of W-3%Re alloy at high temperature, the thermal stability experiments of W and W-3%Re alloy were carried out at (500,700,900 ℃) for 6h. Oxidation experiments were carried out at different temperatures (700,800,900 ℃) for 18h. The phase composition, oxidation kinetics, oxidation products and surface morphology of the oxide film were analyzed by XRD, SEM, LSM800 automatic 3D morphology analyzer and Hysitron TI Premier Nanoindentation apparatus. The results show that the quality of the alloy increases with the extension of oxidation time. During the oxidation process, the grain size of W-3%Re alloy is reduced, the oxidation film can be formed faster, the surface oxide layer is gradually thicker, and the high temperature oxidation resistance of W-3%Re alloy is improved. Compared with W, the chemical stability of the Re oxide in W-3%Re alloy is higher, and it shows a lower oxidation rate constant when it is oxidized at 700℃ for 18h. At this time, the W-3%Re alloy is a weak oxidation grade, and the density of the oxide layer is improved to a certain extent during the oxidation process. The results show that the addition of Re can improve the high temperature oxidation resistance of W material.
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Tian Qinghua, Hu Zhixiang, He Zhiqiang, Guo Xueyi, Zhu Liu, Xu Zhipeng
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240439
Abstract:High-purity indium finds extensive application in the aerospace, electronics, medical, energy, and national defense sectors. Its purity and impurity content significantly influence these applications. In this study, ultrahigh-purity indium was prepared by combining zone refining with vacuum distillation. The average removal efficiency of impurity Sb can approach 95%, while the removal efficiency of impurities Sn and Bi could reach over 95% and the removal efficiency of Si, Fe, Ni, and Pb could reach over 85%. Ultimately, the amount of Sn and Sb impurities was reduced to 2.0 ppb and 4.1 ppb, respectively, and the majority of impurities, including Fe, Ni, Pb, and Bi, were reduced to levels below the instrumental detection limit. The overall impurity removal efficiency was 90.9%, and the indium purity was 7N9.
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Zhang Xiaoyuan, Li Fuguo, Du Yuxuan, Liu Xianghong, Wang Kaixuan, Li Jieyao, Song Minglong
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240444
Abstract:Comparative analysis of the differences in tensile strength and impact toughness between the TC25 alloy and TC25G alloy of Ti-Al-Zr-Sn-Mo-W-Si system titanium alloys was carried out, and the root causes of the differences in impact toughness between the two alloys and the alloy strengthening mechanism were elucidated through the observation of the SEM fracture morphology and the analysis of the TEM microscopic deformation mechanism. The results show that the precipitated phase in the impact fracture of TC25G alloy is ZrSi or TiZrSi compounds, which plays the role of second-phase reinforcement and is conducive to the enhancement of the alloy strength, and the precipitates are conducive to the extension of impact cracks, thus reducing the impact toughness of the alloy. TC25 alloy impact fracture microstructure cracks generally extend along the primary α phase phase boundary, while TC25G alloy impact fracture microstructure cracks through the primary α phase; so that the TC25 alloy crack extension path longer, and thus the alloy has a higher impact toughness. TEM observations show that the number of dislocation slip traces and dislocation plugging in TC25G alloy is significantly higher than that in TC25 alloy. The presence of a large number of plugged dislocations in the vicinity of the precipitates in TC25G alloy results in significant strengthening, leading to a higher strength of the alloy.
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Gao Yubi, Wang Wenjuan, Yang Hui, Wang Xingmao, Xu Jiayu, Zhen Bing, Ding Yutian
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240445
Abstract:In this paper, EBSD, SEM, TEM and quasi-static uniaxial tensile tests were used to study the effects of temperature and twin boundaries on the mechanical properties and Protevin-Le chatelier（PLC) effect of GH3625 alloy. The results show that with the increase of annealing temperature (1000 °C~1160 °C), the recrystallized grains of the annealed specimen grow, resulting in the annihilation of part of the annealed twin boundaries, which reduces the content and strength of the annealed twin boundaries of the alloy. And it is found that the lower the annealing temperature, the greater the critical strain value of the alloy with PLC. At the same time, the tensile deformation of the annealed specimen at 25 °C and 290 °C is mainly dominated by dislocation slip and deformation twin, while at 565 °C, the dislocation slip is mainly dominated by dislocation slip, and a large number of lamination faults are formed. With the increase of deformation temperature, dislocations tend to pass through grain boundaries and annealed twin boundaries, resulting in PLC, weakened grain boundary strengthening effect, and decreased alloy strength. In addition, the specimen with an annealing temperature of 1000 °C has an excellent combination of strength and plasticity in the temperature range of 25 °C~565 °C, which is mainly attributed to the interaction of pre-existing fine grains and a large number of annealed twin boundaries with dislocations, as well as the combined effect of deformed twins and lamination faults formed during tensile deformation. In addition, it is found that the twin content and deformation temperature have a significant effect on the rheological amplitude of the PLC.
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Ge Mao, Jiang Haitao, Zhang Yun
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240449
Abstract:This paper focuses on the AZ31 magnesium alloy, utilizing single-pass hot rolling to fabricate an alloy with the bimodal grain structure, and examines how this structure enhances the alloy’s strength and plasticity. The experimental results show that the formation of the bimodal grain structure is more pronounced at rolling temperatures ranging from 350 ℃ to 450 ℃, especially under conditions of large reduction (≥40%). The optimized proportion and distribution of the bimodal grain structure play a pivotal role in simultaneously enhancing the alloy’s strength and ductility, significantly impacting the mechanical properties. The rolled sheet with the bimodal grain structure achieved an ultimate tensile strength of 258.3MPa and an elongation of 17.1% under a rolling reduction of 40%, with a rolling rate of 75 m/min and a rolling temperature of 400 ℃. Adjusting rolling parameters, including temperature, reduction ratio, and rolling rate, is crucial for optimizing the bimodal grain structure, thereby achieving a balance between improved plasticity and maintained high strength.
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Li changmin, Luo hengjun, Zhao ning, Guo shiqi, Wei minggang, Xiang wei, Cui mingliang, Xie jing, Huang liang
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240451
Abstract:The hot deformation behavior of as-extruded Ti-6554 alloy was investigated through isothermal compression at 700-950 °C and 0.001-1 s-1. The temperature rise under different deformation conditions was calculated, and the curve was corrected. The strain compensation constitutive model of as-extruded Ti-6554 alloy based on temperature rise correction was established. The microstructure evolution under different conditions was analyzed, and the dynamic recrystallization (DRX) mechanism was revealed. The results show that the flow stress decreases with the increase of strain rate and the decrease of deformation temperature. The deformation temperature rise gradually increases with the increase of strain rate and the decrease of deformation temperature. At 700 °C/1 s-1, the temperature rise reaches 100 °C. The corrected curve value is higher than the measured value, and the strain compensation constitutive model has high prediction accuracy. The precipitation of the α phase occurs during deformation in the two-phase region, which promotes the DRX process of the β phase. At low strain rate, the volume fraction of dynamic recrystallization increases with the increase of deformation temperature. The DRX mechanism includes continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX).
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guozilong, lizhaoxi, guowei, liupengkun, lijinglong, xiongjiangtao
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240452
Abstract:This study focuses on the transient liquid phase (TLP) diffusion bonding of GH5188, utilizing a BNi-5 interlayer. Parameters were chosen and optimized for GH5188 alloy and the TLP joining mechanism.SThe microstructure evolution and mechanical properties of the joints were comprehensively examined.SThe relatively complete isothermal solidification zone (ISZ) ensured a reliable connection of the base metal (BM).SInS1110 °C to 1190 °C, higher bonding temperature widened the ISZ and enhanced joint composition homogenization, improving mechanical properties.SHowever, an increase in precipitatedSadversely affected the joint"s mechanical properties.SThe maximum shear strength, reaching 482 MPa, was achieved at 1130 °C, representing 84.6% of the BM strength.SWithin theSpressure range of 5 MPa to 15 MPa, both precipitation phases in the ASZ and voids generated by partial melting increased.SOn the contrary, their sizes decreased significantly with higher bonding pressure, resulting in an upward trend in alloy mechanical properties.SThe maximum shear strength of 490 MPa was attained at a bonding pressure of 15 MPa. The joint exhibited a typical mixed fracture pattern, with the small brittle M23C6 phase and voids significantly impacting mechanical properties.SNanoindentation tests indicated the ASZ as a potential source of cracks.
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Jiang shihui, Di Jinnan, Xu Zaidong, Sun Ssihua, Mao Pingli
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240453
Abstract:In this work, a near β-type Ti-5.5V-4Mo-2.2Cr-Fe-3.6Al alloy was designed based on the multi-alloying principle of critical molybdenum equivalent ([Mo]eq), combined with parameters such as electron concentration (VEC), Bo-Md that can influence the stability of β phase. The alloy was subjected to solid solution, intermediate annealing during the rolling process, and aging treatment. The microstructure and mechanical properties of the alloy were analyzed. The results showed that martensitic transformation occurs in the alloy during rolling. The grain size of the alloy after annealing during the rolling process is only 38 μm, due to the martensite has a hindrance to grain boundary migration. Then it has good strength-plasticity matching, the tensile yield strength reaches 1150 MPa and the elongation is more than 10%. A large number of α phases are precipitated in the microstructure of the rolled alloy after aging treatment, which further improves the properties of the alloy. The strength of the alloy exceeds 1500 MPa and the elongation is more than 5 %.
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Xing Quanyi, Zhou Ge, Zhang Haoyu, Che Xin, Wang Wen Jingzi, Chen Lijia
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240455
Abstract:In this paper, self-designed Al8Si0.4Mg0.4Fe aluminium alloy was modified with Sr, and a solid solution + aging treatment was applied to the alloy to regulate its microstructure and properties. The results show that: after the modification treatment, the room temperature tensile strength of the alloy did not change much, the elongation at break slightly improved (1.82%→3.34%), and the electrical conductivity significantly increased from 40.1%IACS before the modification treatment to 42.0%IACS. After the modification, the alloy underwent a solid solution treatment at 515°C for 8 hours and subsequently an aging treatment at temperatures 180℃, 200℃, 220℃ and 240℃ for a duration of 6 hours. With the increase of aging temperature, the electrical conductivity increased monotonously from 41.4% IACS to 45.5% IACS, but the room temperature tensile strength increased first and then decreased. At 200℃, the electrical conductivity and room temperature tensile strength of the alloy showed a good coordination, the electrical conductivity was 42.5%IACS, and the room temperature tensile strength was 282.9MPa. When the aging temperature continues to rise, the alloy is overaged. Although the conductivity is still rising, the tensile strength at room temperature decreases sharply, and it is only 177.1MPa at 240℃.
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Jianbo Guo, Zhengjun Liu, suyunhai
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240458
Abstract:The failure of mechanical parts is mainly caused by three types of reasons: wear, corrosion, and fatigue. Among these three failure modes, wear and tear of mechanical components notably increase energy consumption and lead to substantial economic losses. Preparation of Fe-Cr-C-B-Ti-Y wear resistant cladding metals by plasma cladding method. The wear performance of cladding metals was analyzed using the MLS-23 rubber wheel wet sand wear tester. XRD, SEM, EBSD, and TEM were employed to examine the phase composition and microstructure of the cladding metals, followed by a discussion on the cladding metals strengthening and wear mechanisms. The results indicate that the microstructure of Fe-Cr-C-B-Ti-Y cladding metals is composed of austenite γ-Fe+M23(C,B)6 eutectic carbide+TiC hard phase. As the amount of Y2O3 added increases, the hardness and wear of the deposited metal show a trend of first increasing and then decreasing. When the Y2O3 content is 0.4%, the precipitation of TiC hard phase and M23(C,B)6 type eutectic carbides reaches its maximum, and the grain size in the microstructure is the smallest. The forming performance of the cladding metal is the best, and the wetting angle is the smallest, only 52.2 °. At this point, the rockwell hardness value of the cladding metal is 89.7 HRC, and the wear weight loss is 0.27g. The wear mechanism of cladding metals is mainly abrasive wear, and the material removal process involves micro cutting and plowing.
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Yihang Yang, Fang Yang, Jixing Liu, Yixuan He, Shengnan Zhang, Guo Yan, Pingxiang Zhang
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240226
Abstract:Because of the special dimension effect and interface effect, thin film materials have unique advantages compared with bulk materials. It has been found that single-layer FeSe superconducting films grown on SrTiO3 (STO) substrates significantly increase the superconducting transition temperature (Tc), which makes the study of FeSe superconducting films a new direction to understand the mechanism of unconventional superconductors. In this paper, the recent research achievements on the preparation of Fe(Se,Te) superconducting films and the enhancement of Tc by stress effect and interface effect are reviewed.
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