High-Temperature Mechanical Properties of TaWHf Alloy Doped with Re and C
Bai Run, Huang Li, Liu Hui, Wang Feng, Cai Xiaomei, Xia Mingxing, Sun Rui, Bai Wei, Hu Ping, Zhang Wen
Abstract:The high-temperature mechanical properties of Ta-8W-2Hf alloy doped with Re (1wt%) and C (0.01wt%) were investigated at room temperature, 1300 °C, and 1500 °C. Results show that fine and dispersed precipitates Ta2C are detected in crystallized TaWHfReC alloy, which significantly enhance mechanical properties of the alloy. The strength of TaWHfReC alloy is much higher than that of TaWHf alloy, especially at 1300 and 1500 °C. At 1300 °C, the ultimate tensile strength of the TaWHf alloy is 322 MPa, while that of the TaWHfReC alloy reaches 392 MPa. When the temperature rises to 1500 °C, precipitated-phase strengthening remains effective in the TaWHfReC alloy, achieving an ultimate tensile strength of 268 MPa. Additionally, at 1300 °C, the elongation of the TaWHfReC alloy reaches 23.5%, which is nearly twice of that of the TaWHf alloy. The significant improvement in the mechanical properties of the TaWHfReC alloy at elevated temperatures is primarily attributed to the interaction between dislocations and the fine Ta2C precipitated phase. The fine and uniformly distributed particles effectively inhibit dislocation motion and exhibit a pronounced strengthening effect at high temperatures.
Zhao Lun, Sun Zhichao, Wang Chang, Zhang Pengsheng, Tang Shuai, Zhang Baoxin
Abstract:Four types of Mg-5Zn porous scaffolds with different pore geometries, including body-centered cubic (bcc), the rhombic dodecahedron (RD), gyroid (G), and primitive (P) types, were designed and fabricated using selective laser melting. Their forming quality, compression mechanical properties, and degradation behavior were investigated. Results indicate that the fabricated scaffolds exhibit good dimensional accuracy, and the surface chemical polishing treatment significantly improves the forming quality and reduces porosity error in porous scaffolds. Compared to the ones with rod structures (bcc, RD), the scaffolds with surface structures (G, P) have less powder particle adhesion. The G porous scaffold exhibits the best forming quality for the same design porosity. The predominant failure mode of scaffolds during compression is a 45° shear fracture. At a porosity of 75%, the compression property of all scaffolds meets the compressive property requirements of cancellous bone, while bcc and G structures show relatively better compression property. After immersion in Hank's solution for 168 h, the B-2-75% pore structure scaffold exhibits severe localized corrosion, with fractures in partial pillar connections. In contrast, the G-3-75% pore structure scaffold mainly undergoes uniform corrosion, maintaining structural integrity, and its 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.
Thermal Deformation and Grain Control of Extruded Profile for 2196 Al-Li Alloy
Li Xiang, Li Hongying, Tian Yuxing, Cao Hailong, Niu Guanmei, Wang Yan, Rao Mao, Han Jiaqiang, Liu Cheng, Zheng Ziqiao
Abstract:Flow behavior and grain structure evolution were studied for 2196 aluminum-lithium alloy during hot compression deformation. Based on extrusion simulation and profile trial production, grain structure control of typical I-shaped thin-walled profiles was achieved. The results show that the alloy exhibits excellent hot deformability in a relatively wide parameter range. The dominate mechanism of microstructure evolution is dynamic recovery, although some localized dynamic recrystallization is also observed. At lower temperatures (350, 400 ℃) and higher strain rates (10 s-1), strain concentration leads to a small amount of local dynamic recrystallization. Compared to experimental compression deformation, the larger strain of extrusion process promotes the formation of dynamic recrystallization. The differences of deformation conditions on profile section lead to non-homogeneous grain structure. Based on the equipment capability, relatively uniform microstructure be obtained under deformation conditions of 430 ℃ and strain rate of 0.005–0.95 s-1 on profile section, while maintaining lower fraction of recrystallization and abundant sub-grain structure, which is benefit for the strength and toughness matching.
Guo Zilong, Li Zhaoxi, Guo Wei, Liu Pengkun, Li Jinglong, Xiong Jiangtao
Abstract:The transient liquid-phase (TLP) diffusion bonding of GH5188 with a BNi-5 interlayer was focused on. Parameters were chosen and optimized for GH5188 alloy according to the TLP joining mechanism. The microstructure evolution and mechanical properties of the joints were studied. Results show that the relatively complete isothermal solidification zone (ISZ) ensures a reliable connection of the base metal (BM). Within the temperature range of 1110–1190 °C, higher bonding temperatures can widen ISZ and promote joint composition homogenization, thus improving mechanical properties. However, the increase in precipitated phase has an adverse effect on the mechanical properties of the joint. The maximum shear strength, reaching 482 MPa, is achieved at 1130 °C, representing 84.6% of BM strength. Within the pressure range of 5–15 MPa, both precipitated phases in adiabatic solidification zone (ASZ) and voids generated by partial melting increase. On the contrary, their sizes decrease significantly under higher bonding pressure, resulting in an upward trend in alloy mechanical properties. The maximum shear strength of 490 MPa is attained at a bonding pressure of 15 MPa. The joint exhibits a typical mixed fracture pattern, with the small brittle M23C6 phase and voids significantly impacting mechanical properties. Nano-indentation tests indicate that ASZ is a potential source of cracks.
Shu Guogang, Xuan Weidong, Yu Xu, Duan Fangmiao, Bai Xiaolong, Ge Bingming, Wang Baojun, Zhang Zhenqiang, Zhang Chengjiang, Ren Zhongming
Abstract:The formation mechanism of freckle defects in large-sized UGTC47 directionally-solidified columnar crystal blades for heavy-duty gas turbines and their effect on the stress rupture property were investigated using optical microscope, scanning electron microscope, and endurance performance test. The results indicate that freckle defects form in both the middle and root regions of the blade tenon, whose formation mechanism is the density inversion caused by liquid phase segregation, resulting in fluid convection under the action of gravity, and leading to the fracture of dendrite arms and the formation of freckles. At 900 ℃/380 MPa, the proportion of freckle area has a significant impact on the endurance performance of the UGTC47 alloy. With the increase in freckle content, the stress rupture life of the alloy is decreased from 131.83 h without freckle defects to 33.66 h with freckle content of 62%.
Solidification Structure and Quasicrystal Regulation of Mg-Zn-Gd Casting Alloys
Wang Chunhui, Yang Guangyu, Qin He, Kan Zhiyong
Abstract:The I phase (Mg3Zn6Gd, icosahedral quasicrystal phase) is widely considered as the strengthening phase in Mg-Zn-Gd system alloys, providing more significant improvements in the mechanical properties compared to the W phase (Mg3Zn3Gd2, 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 by 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 and 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. The increased solidification cooling rates and Zn/Gd atomic ratio inhibit the W phase and promote the formation of the I phase during Mg-Zn-Gd alloy preparation, resulting a higher proportion of the I phase in the alloy.
wang shuai, Liu Zeyu, Ye Jianlin, Wang Ge, Guo Yangyang, Pu Xuanyu, Zeng Rongchang, Ren Lingbao, Shan Zhiwei
Abstract:Laser beam welding (LBW) has emerged as one of the most promising connection techniques for lightweight equipment fabricated by magnesium alloys due to the less deformation, narrow heat-affected zone, and excellent welding efficiency. However, a variety of porosity defects are commonly found in the laser welded joints. The causes of laser-welded pores are complicated. The number, size and distribution characteristics of porosity affect the mechanical properties of magnesium alloy joints, and thus seriously affecting the reliable applications of magnesium alloy lightweight equipment. This study reviewed the mechanism of pores formation in the microstructure of laser welding joints of magnesium alloys, and discussed the influence of porosity on mechanical properties. The pore manipulation was proposed. The key basic research and applications of LBW of magnesium alloys were pointed out. This review may provide valuable insights for the development of joining and manufacturing technology of magnesium alloy lightweight parts in automotive and aerospace fields.
Zheng Yongfeng, Hu Xiaofeng, Yang Zhirong, Jiang Haichang, Rong Lijian
Abstract:The effects of V content (0.1wt%, 0.2wt%) on the carbide evolution and mechanical properties of ultra-clean 30Cr2Ni4MoV rotor steel under different heat-treatment states (as tempered and as step cooled) were investigated by SEM, EBSD, XRD, TEM, and APT. The results show that both tempered steels show lath martensite microstructure. The increase in V content has no obvious effect on the carbide type (M23C6, M2C and MC) and size, but promotes the precipitation of more and finer V-riched carbides MC, which refines the prior austenite grain size of the 0.2V steel. The refinement of grain size and precipitation of finer MC carbides increase the yield strength of the 0.2V steel by 147 MPa through grain refining strengthening and precipitation strengthening. After step cooling heat-treatment, the microstructures and the type of carbides in both steels remain stable and the size of carbide grows slightly. Meanwhile, the yield strength of them shows a slight decrease due to the carbide coarsening. As for 0.2V steel, the mobility of dislocations decreases due to precipitation of more MC carbides, which induces the decrease in critical stress σf of crack propagation and promotes the tendency of crack initiation and propagation. Therefore, compared with that of 0.1V steel, the fracture appearance transition temperature of 0.2V steel increases by 21 ℃.
- Current Issue |
- Latest Issue |
- Online First |
- Archive |
- Virtual Collection |
- Highlights
-
Zheng Deyu, Xia Yufeng, Zhou Jie
2025,54(12):3000-3009 DOI: 10.12442/j.issn.1002-185X.20240716
Abstract:Hot compression tests for GH4706 alloy were performed at a true strain of 1.2 within the temperature range of 950–1150 °C and the strain rate range of 0.001–1 s-1. The optimal hot deformation temperature and strain rate range were determined using nephogram maps of dynamic recrystallization fraction, average grain size, and grain distribution standard deviation. Processing maps at true strains from 0.4 to 0.9 were generated based on flow stress curves to identify the strain corresponding to optimal microstructure homogenization efficiency at various temperatures and strain rates. Results show that within the optimal parameter range, under the conditions of 1150 °C and 0.01 s-1, the true strain of about 0.6 results in the optimal microstructure homogenization efficiency. The grain orientation spread maps obtained from the experiment also confirms this conclusion. This study provides an effective method for microstructure homogenization control of GH4706 alloy and an effective reference for the minimum strain threshold of the local part of the forging in engineering.
-
Wang Yingdi, Zhang Guiqing, Yang Taisen, Liang Xuewei, Su Yunhai
2025,54(12):3010-3023 DOI: 10.12442/j.issn.1002-185X.20240744
Abstract:A novel nitrogenous nickel-based deposited metal was prepared by gas metal arc welding. Subsequently, solid solution treatment as well as solution and aging treatments were conducted on the prepared metal to study the evolution of microstructure and tensile properties at different states. Results show that the high-temperature tensile strength of the deposited metal exhibits good performance after the addition of W and N. The grain size of the sample is large, and petal-like Laves phase appears at the grain boundaries. After solid solution treatment, the grain size decreases, and the Laves phase disappears. However, both the yield strength and elongation of the deposited metal decrease. The grain size of the samples after solid solution and aging treatment is more uniform, nanoscale M(C, N) phases are precipitated within the crystals, and M23C6 phase forms at grain boundaries. The yield strength and ultimate tensile strength of this sample are higher than those of the other samples, but its plasticity is the lowest. The main deformation mechanism is the unit dislocation a/2<110> cutting the precipitation phase.
-
Effect of Heat Treatment on Fracture Characteristics and Serrated Yielding of Inconel 718 Superalloy
Zhang Min, Xue Chun, Ma Chuanchuan, Li Tuo, Chu Zhibing, Tuo Leifeng
2025,54(12):3054-3059 DOI: 10.12442/j.issn.1002-185X.E20240696
Abstract:Due to the gradually prominent impact of fracture characteristics and serrated yielding in the application of nickel-based superalloys, the hot tensile properties of Inconel 718 superalloy were studied, including fracture behavior, mechanical properties, and plastic behavior. The experiments adopted three heat treatment regimes and two tensile directions. Results show that various heat treatments make grain sizes different. The larger-sized grains make the vertical surface uneven, which also decrease the number of grain boundaries and carbides, restricting the occurrence of dimples and ultimately reducing the material plasticity. The reduced grain boundaries can decrease dislocations, increase the demand for thermal activation energy, and transform the serration mode of serrated yielding. In addition, various heat treatments also make precipitates different. Carbides can promote the formation of dimples. The needle-shaped δ phase precipitates at grain boundaries and twin boundaries, and slightly inclines towards the rolling direction. Therefore, its pinning effect is outstanding along the transverse direction, which can affect the dimple aggregation and the dislocation movement, ultimately exhibiting anisotropy in fracture characteristics, mechanical properties, and serrated yielding.
-
Wu Yin, Zhang Hao, Zhu Yuping, Fang Shimin, Ding Yaoyao, Liang Liwen, Yan Guangqiang, Qiu Zixiang, Wang Haixuan, Dongye Shengshuan, Tian Miaocheng, Yang Yang, Huang Qizhong, Zheng Yongjian
2025,54(12):3097-3104 DOI: 10.12442/j.issn.1002-185X.20240487
Abstract:This study focuses on the selective laser melting (SLM)-formed ZGH451 nickel-based superalloy, revealing the mechanism that 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 of ZGH451 nickel-based superalloy in the SLM process 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 45 J/mm3, the unfused defects in the alloy are densely distributed along the building direction. Once exceeding 140 J/mm3, the probability of keyhole and pore formation sharply increases. These defects can induce cracks under stress. The more the WC and other carbide particles precipitated between dendrites, the greater the grain misorientation, and the higher the alloy's crack sensitivity. The deposited 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.
-
Nan Lingxin, Qi Yanfei, Xu Pengfei, Li Yungang, Pang Binghe, Liu Kun
2025,54(12):3113-3122 DOI: 10.12442/j.issn.1002-185X.20240509
Abstract:Superalloys have a very important position in the development of nuclear fusion and other fields. 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 conducted at the temperature of 500, 700, and 900 ℃ for 6 h. Oxidation experiments were conducted at the temperature of 700, 800, and 900 ℃ for 18 h. 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 prolongation of oxidation time. During the oxidation process, the grain size of W-3%Re alloy is reduced, the oxidation film forms 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 W-3%Re alloy shows a lower oxidation rate constant when it is oxidized at 700 ℃ for 18 h. 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. This indicates that the addition of Re can improve the high temperature oxidation resistance of W material.
-
Li Jiadong, Shao Huayang, Liu Shiwei, He Chen, Zhao Yuhui, Zhao Jibin
2025,54(12):3174-3185 DOI: 10.12442/j.issn.1002-185X.20240539
Abstract:The Nb and WC composite-strengthened Grade 4 Ni-based superalloy coatings were prepared on 304NG stainless steel substrate by laser melting deposition technology. The effects of Nb and WC mass fraction on the microstructure, microhardness and wear resistance of the Ni-based superalloy coatings were studied. The results show that the coating is well combined with the substrate without obvious cracks, pores and other defects. The addition of alloying element Nb leads to new hard phases NbC and Nb6C5, which make the eutectic structure of the alloy denser and also improves the hardness and wear resistance of the coating. The coating with 10wt% Nb+15wt% WC shows the best wear resistance. The continuous eutectic structure changes from long strip and reticulation to four shapes of separated short strip, block, granular and fishbone. At the same time, the addition of WC transforms the wear mechanism of the coating from abrasive wear and adhesive wear to fatigue wear.
-
Wang Yao, Ren Xiaona, Chen Zhipei, Ge Changchun
2025,54(12):3186-3191 DOI: 10.12442/j.issn.1002-185X.20240541
Abstract:Different temperature annealing treatments were conducted on a laser powder bed melted FGH4096M nickel-based superalloy. The microstructure of the alloy was analyzed using SEM and EBSD, while tensile tests were performed to investigate the impact of the annealing process on the microstructural evolution and mechanical properties of the laser powder bed melted FGH4096M superalloy. The results reveal that as the annealing temperature increases, dendritic and columnar crystals gradually disappear in the formed alloy; a significant precipitation of γ′ phase is observed when the annealing temperature is 900 ℃. Additionally, there is a gradual increase in hardness until 800 ℃, along with an upward trend in both tensile strength and yield strength; however, fracture elongation rate remains low at only 5%. Analysis of grain orientation difference distribution indicates that annealing can partially eliminate residual stress. These research findings provide valuable data support for enhancing the performance of laser powder bed melted nickel-based superalloys.
-
Bai Run, Huang Li, Liu Hui, Wang Feng, Cai Xiaomei, Xia Mingxing, Sun Rui, Bai Wei, Hu Ping, Zhang Wen
2025,54(12):2985-2992 DOI: 10.12442/j.issn.1002-185X.20250168
Abstract:The high-temperature mechanical properties of Ta-8W-2Hf alloy doped with Re (1wt%) and C (0.01wt%) were investigated at room temperature, 1300 °C, and 1500 °C. Results show that fine and dispersed precipitates Ta2C are detected in crystallized TaWHfReC alloy, which significantly enhance mechanical properties of the alloy. The strength of TaWHfReC alloy is much higher than that of TaWHf alloy, especially at 1300 and 1500 °C. At 1300 °C, the ultimate tensile strength of the TaWHf alloy is 322 MPa, while that of the TaWHfReC alloy reaches 392 MPa. When the temperature rises to 1500 °C, precipitated-phase strengthening remains effective in the TaWHfReC alloy, achieving an ultimate tensile strength of 268 MPa. Additionally, at 1300 °C, the elongation of the TaWHfReC alloy reaches 23.5%, which is nearly twice of that of the TaWHf alloy. The significant improvement in the mechanical properties of the TaWHfReC alloy at elevated temperatures is primarily attributed to the interaction between dislocations and the fine Ta2C precipitated phase. The fine and uniformly distributed particles effectively inhibit dislocation motion and exhibit a pronounced strengthening effect at high temperatures.
-
Li Yuanjie, Zhao Yuqing, Liang Chenyu
2025,54(12):2993-2999 DOI: 10.12442/j.issn.1002-185X.20240726
Abstract:Amorphous Ga2O3 (a-Ga2O3) thin films were prepared on flexible polyimide, rigid quartz glass, and Si substrates via radio frequency magnetron sputtering at room temperature. The effect of oxygen/Ar flow rate ratio on the structure, optical property, surface morphology, and chemical bonding properties of the a-Ga2O3 films was investigated. Results show that the average optical transmittance of the a-Ga2O3 films is over 80% within the wavelength range of 300–2000 nm. The extracted optical band gap of the a-Ga2O3 films is increased from 4.97 eV to 5.13 eV with the increase in O2/Ar flow rate ratio from 0 to 0.25, due to the decrease in concentration of oxygen vacancy defects in the film. Furthermore, the optical refractive index and surface roughness of the a-Ga2O3 films are optimized when the O2/Ar flow rate ratio reaches 0.25. X-ray photoelectron spectroscopy analysis also shows that the proportion of oxygen vacancies (VO) and Ga-O chemical bonds in the O 1s peak is gradually decreased with the increase in O2/Ar flow rate ratio from 0 to 0.25, proving that increasing the O2/Ar flow rate ratio during film growth can reduce the concentration of oxygen vacancy defects in a-Ga2O3 films. In this case, a-Ga2O3 with optimal properties can be obtained. This work provides a research basis for high-performance flexible and rigid deep ultraviolet solar-blind detection devices based on a-Ga2O3 films.
-
Zhang Qiankun, Deng Liuke, Zhao Xinyue, Su Kexin, Cao Dongcheng, Bai Youzhang, Wu Liang, Xiao Yifeng, Qian Jinwen, Huangfu Ying
2025,54(12):3024-3031 DOI: 10.12442/j.issn.1002-185X.20240777
Abstract:Fine nickel powders with a narrow particle size distribution were prepared by reducing nickel hydroxide in aqueous solution. The formation and reduction pathways of nickel powder were analyzed, as well as the effects of the molar ratio of hydrazine hydrate to nickel hydroxide, hydrazine concentration, and the dosage of surfactant PEG6000 on particle size, surface morphology, and dispersion. Results reveal that the nickel particle nucleation occurs on the nickel hydroxide surface, and the nickel hydroxide gradually dissolves during the reaction. With the increase in molar ratio of hydrazine hydrate to nickel hydroxide, the nickel particle size is initially decreased and then increased. Higher hydrazine hydrate concentrations result in smaller particle sizes. A small amount of PEG6000 surfactant can improve dispersion of nickel particles, but a higher amount of PEG6000 surfactant results in the maintenance of the morphology of nickel hydroxide. Adjusting the surfactant dosage can control the average particle size between 1–2 μm.
-
Shi Changgen, Jiang Jialin, Wang Haitao, Luo Xuchuan, Feng Ke
2025,54(12):3032-3047 DOI: 10.12442/j.issn.1002-185X.20240670
Abstract:To further reduce the explosive thickness and to improve the bonding quality of titanium/steel composite plates, explosive welding experiments of TA1/Q235 were conducted using a low detonation velocity explosive (53#) under the guidance of the explosive welding lower limit principle with the flyer plate thicknesses of 1, 2, and 4 mm and gaps of 3, 6, and 8 mm. The weldability window for titanium/steel explosive welding was calculated, and a quantitative relationship between dynamic and static process parameters was developed. A β-Vp high-speed inclined collision model was proposed, and two-dimensional numerical simulations for the explosive welding tests were performed using the smoothed particle hydrodynamics (SPH) algorithm, revealing the growth evolution mechanisms of the typical waveform morphology characteristics. Through microstructural characterization techniques, such as optical microscope, scanning electron microscope, energy dispersive spectrometer, and electron backscattered diffractometer, and mechanical property tests in terms of shear strength, bending performance, and impact toughness, the microstructure and mechanical properties of the interfaces of explosively welded TA1/Q235 composite plates were investigated. Results show that the quality of interface bonding is excellent, presenting typical waveform morphology with an average interface shear strength above 330 MPa and an average impact toughness exceeding 81 J. All samples can be bent to 180° without significant delamination or cracking defects.
-
Li Tong, Chang Yixiang, Zhang Tong, Zhang Yi, Yin Yansheng, Lu Jinlin
2025,54(12):3048-3053 DOI: 10.12442/j.issn.1002-185X.20240677
Abstract:To improve the mechanical properties of 2024 aluminum alloy, a kind of diamond-like carbon (DLC) film was deposited on the surface of 2024 aluminum alloy by plasma-enhanced chemical vapor deposition technique. The effects of acetylene gas on the microstructure, hardness, wear resistance, and adhesion of DLC film were investigated by field emission scanning electron microscope, nano-indentation tester, and friction-wear tester. The results indicate that the thickness of the DLC film increases gradually with increasing the proportion of acetylene. There is an obvious transition layer between the DLC film and matrix. When the ratio of argon to acetylene is 1:3, the hardness of DLC film is enhanced significantly because of the content changes of sp3 and sp2 bonds within the film. At the same time, the friction coefficient of DLC film is reduced.
-
Ming Yue, You Guoqiang, Wang Xiaoxi, Yang Feng, Zhang Jun
2025,54(12):3060-3064 DOI: 10.12442/j.issn.1002-185X.20240672
Abstract:The oxidation behavior and mechanism of Mg-Ca alloys in air and under flame exposure were studied. Results show that for the oxidation in air, the Mg-Ca-O oxide film with Ca accumulation and low Mg vapor pressure on the surface of Mg-Ca alloys with high Ca content shows good protective effect. However, the falling off phenomenon of the oxide film on Mg2Ca results in the further oxidation. Hence, the Mg-Ca alloys with high Ca content only show good protective effect. For the oxidation in flame, the molten alloys release the Ca atoms to diffuse outward. The Mg-Ca-O oxide film with high Ca accumulation layer forms in Mg-Ca alloys with high Ca content. Despite the high Mg vapor pressure in the molten alloy, the Mg-Ca-O oxide film with high Ca accumulation layer shows excellent protective effect.
-
Zhu Hongtao, Qin Jian, Jing Peiyao, Su Xu, Zhao He, Song Xinyi
2025,54(12):3077-3083 DOI: 10.12442/j.issn.1002-185X.20240371
Abstract:The diamond model was simplified to hexahedron based on the macroscopic morphology, and the finite element model of laser brazing diamond was established, and this model was optimized for brazing material climbing. The distribution characteristics of the maximum residual stress of the diamond coating were obtained, and the mechanism of the maximum residual stress on the surface defects of the coating was investigated with experiments. The measured trend of diamond residual stress by Raman spectroscopy agrees well with the calculated results, and the diamond post-weld residual stress is compressive stress. Finally, the mechanism of the influence of diamond post-soldering residual stress on the wear resistance failure of the coating was explored in combination with the wear resistance experiments. The results show that diamond is subjected to appropriate residual compressive stress to help improve the brazing layer''s hold on diamond, and with the increase in diamond post-soldering residual stress, the wear resistance of the coating shows a tendency of first enhancement and then decreasing.
-
2025,54(12):3084-3090 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 rates was studied, and the tensile properties were investigated. The results show that the microstructure of base metal is a mixture of α phase and β phase. The microstructure of heat affected zone are equiaxed and primary α phase and needle martensite α′ phase dispersed in the transformed β phase. The distribution of two kinds of microstructures in the heat-affected area is affected by the welding thermal cycle. The microstructure of weld seam mainly consists of α′ martensite phase. The decrease in welding gas flow rate and the increase in welding energy density result in coarse and more scattered martensitic grains. The tensile strength of welded joint is higher than that of base metal.
-
Meng Shuaiju, Song Jinlong, Chen Keyi, Cui Min, Wang Lidong, Bi Guangli, Cao Chi, Yang Guirong
2025,54(12):3091-3096 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-grained 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 occur at the initial grain boundaries of the fine-grained B6 alloy during the multi-pass ITF-ECAP processing. In addition, a large amount of submicron sized Mg3Bi2 phase precipitates 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, i.e. yield strength and elongation reach (315.6±3.6) MPa and (22.3±1.0)%, respectively.
-
Li Qianru, Zhang Fan, Niu Shiyu, Wang Ying, Yang Zhenwen
2025,54(12):3105-3112 DOI: 10.12442/j.issn.1002-185X.20240495
Abstract:The influence of Ni interlayer thickness on the microstructure, mechanical properties, and corrosion resistance of Zr-4/Nb/Ni/316SS diffusion bonded joints was investigated. The 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 the increase in Ni interlayer thickness, reaching a peak value of 380 MPa at 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 the thicker Ni interlayers are more effective in alleviating residual stress, but excessively thick interlayers lead to a reduction in shear strength due to their enhanced ductility. Additionally, the corrosion resistance of the joints was assessed by full immersion corrosion tests. The results indicate that the corrosion rate decreases with a reduction in Ni interlayer thickness, and the optimum corrosion resistance of joint is achieved at an interlayer thickness of 10 μm. In conclusion, it is recommended that the Ni interlayer thickness needs to be maintained between 10 μm and 30 μm to achieve a balance between mechanical properties and corrosion resistance.
-
Ren Qisen, Wu Lixiang, Liu Yang, Xu Liang, Guo Weiming, Liu Weiqiang
2025,54(12):3123-3127 DOI: 10.12442/j.issn.1002-185X.20240518
Abstract:ZrC-SiC composite matrix dispersion coated particle fuel surrogate pellets were prepared by spark plasma sintering (SPS) process. The effects of different TRISO (TRistructural ISOtropic) packing fraction on the microstructure and sintering densification process of surrogate pellets were investigated, and the distribution of TRISO particles was characterized. The results show that under the sintering conditions of 1900 ℃/ 30 MPa/10 min, dispersion coated particle fuel pellet samples with TRISO packing volume fraction up to 40%, uniform particle distribution, integral microstructure and good matrix densification can be obtained. The TRISO packing fraction has little effect on the sintering densification process of fuel pellet samples.
-
Han Meng, Ding Chao, Xu Shenghang, Huang Minghao, Chang Cheng, Song Chunnan, Liu Shiqiu, Yang Xin, Tang Huiping
2025,54(12):3128-3138 DOI: 10.12442/j.issn.1002-185X.20240422
Abstract:Based on the diamond-type triply periodic minimal surface (D-TPMS) lattice structures, two types of TPMS lattice structure models of homogeneous and variable density were designed and prepared by the regulation method of linear gradient wall thickness and selective laser melting technology. The effects of relative density, printing direction and model type on the mechanical properties and energy absorption characteristics were analyzed, and the stress distribution and damage mechanism of the variable-density lattice structures were verified by the finite element method. The results show that the damage of the homogeneous TPMS lattice structure is 45o shear fracture, which occurs at the early stage of plastic deformation; the damage of the variable density TPMS lattice structure is interlayer collapse, and the overall structure has excellent load bearing and energy absorption capacity. When the relative density of the TPMS lattice structure is 0.275, the ultimate compressive strength of the homogeneous TPMS lattice structure is up to 193.8 MPa, the deformation amount is 7.7%, and the cumulative value of energy absorption is 11.76 MJ/m3, whereas the ultimate compressive strength of the variable-density TPMS lattice structure is up to 221.4 MPa, and the structure is still intact when the deformation amount is 50%, and the cumulative value of energy absorption is up to 77.52 MJ/m3, which is 6.59 times higher than that of the homogeneous structure. It is demonstrated that the variable-density TPMS lattice structure has good energy absorption effect and excellent load-bearing performance, which has a significant application prospect in the field of collision avoidance and energy absorption.
-
Chen Zhipei, Ren Xiaona, Wang Peng, Wang Yao, Ge Changchun
2025,54(12):3139-3146 DOI: 10.12442/j.issn.1002-185X.20240528
Abstract:Y-Hf co-doped AlCrFeNiCu high entropy alloy (HEA) coating was prepared on the surface of zirconium alloy rod by high-speed laser cladding (HSLC) technique. The microstructure, microhardness, and high-temperature oxidation resistance of the coating were tested and analyzed. The results show that there is mutual diffusion of elements between the bottom of the coating and the substrate, and the width of the heat affected zone is about 35 μm. The microstructure of the coating is mainly composed of black dendrite zone and gray white interdendrite zone. The composition of the coating is uniform and the hardness is as high as 830 HV. The main reasons for the high hardness of the coating are solution strengthening, lattice distortion and slow diffusion effect. The structural integrity of the coating can be maintained after oxidation at 1200 ℃ for 90 min. The coating has a low oxidation rate, and the oxidation process follows the growth kinetics curve. The oxides on the surface are mainly composed of Al2O3 and Cr2O3, which improves the high-temperature oxidation resistance of zirconium alloy.
-
Sun Lei, Yang Pengfei, Sun Qi, Yang Zhiyuan, Zhao Yuan, Gao Ying, Zhang Jiazhen
2025,54(12):3147-3155 DOI: 10.12442/j.issn.1002-185X.20240534
Abstract:TC4 alloy is one of the most widely used aviation materials. Laser surface remelting (LSR) technique can effectively improve the mechanical properties of TC4 alloy, but the strengthening mechanism of LSR on the mechanical properties of TC4 alloy with bimodal microstructure is still unclear. In this study, LSR treatment was conducted on the front and back of TC4 samples, and then the mechanical properties and tribological properties were tested. Systematic characterization was performed by TEM, EBSD, SEM, and other instruments. The synergistic strengthening mechanism between layered heterogeneous structure and bimodal microstructure was discussed. The results show that the remelted layer is composed of coarse lath martensite (CLM), fine lath martensite (FLM) with scattered orientations, and partially parallel
compression twins. When the remelted layer undergoes plastic deformation, dislocations are activated, tangled, and piled-up in CLM. FLM and twins wrapped around CLM hinder the transfer of dislocation slip at the interface, resulting in a significant increase in the yield strength of TC4 alloy with bimodal microstructure to (879±6) MPa, an increase in tensile strength to (1035±11) MPa, and a reduction in number of the fatigue cracks during wear testing. -
Hong Chunfu, Jia Zhengfa, Zhao Kaile, Zhao Guilin, Shu Linxiang, Zou Linchi, Dai Pinqiang
2025,54(12):3156-3163 DOI: 10.12442/j.issn.1002-185X.20240537
Abstract:50%ZrW2O8/Al composites were prepared by spark plasma sintering. The effect of sintering temperatures on the microstructure, phase composition, density, thermal expansion coefficient and thermal conductivity of the composites was studied. The results show that the composites sintered at different temperatures contain γ-ZrW2O8. As the sintering temperature gradually increases from 475 ℃ to 575 ℃, the density and content of γ-ZrW2O8 in the composites gradually increase. After a process of stress relief by the first thermal expansion test from room temperature to 300 °C, the content of γ-ZrW2O8 in the composite material is significantly reduced. The second thermal expansion test reveals that as the sintering temperature increases, the thermal expansion coefficient first increases and then decreases, with the sample sintered at 525 °C being the highest (4.6×10–6 K–1). The sintering density of the composite significantly affects its performance. The ZrW2O8/Al composite sintered at 525 °C presents both the highest density (92.9%) and thermal conductivity (31.9 W/m·K). 525 ℃ is the optimal sintering temperature that takes into account the composition stability and sintering density of the composites.
-
Shang Xiaofeng, Cai Lingzhi, Liu Shiwei, Zhao Yuhui, He Chen, Zhao Jibin
2025,54(12):3164-3173 DOI: 10.12442/j.issn.1002-185X.20240538
Abstract:Densely moulded sedimentary specimens without tissue defects were prepared by laser melting and deposition of titanium-based powders. The effects of Fe content on the microstructure, phase type and content and mechanical properties of TC4 specimens in the as-deposited state were investigated. The results show that with the addition of Fe, the size of α-Ti decreases, the net-basket microstructure is refined, and the as-deposited specimens are transformed from robust columnar crystals to fine and uniform equiaxial crystals in the forming direction. The average grain size of the specimen with 3wt% Fe is 160.6 μm, which is about 76% smaller than that of the specimen without added Fe. Combined with the XRD results, it can be obtained that the microstructure of the specimen consists of a large amount of α-Ti and a small amount of β-Ti, and the content of β-Ti increases slightly with the addition of Fe. The addition of Fe can significantly improve the tensile properties of the specimens, in which the tensile strength and yield strength of 3wt% Fe specimens are increased by 15.5% and 18.0%, respectively, and the post-break elongation is increased by about 60% compared with those of TC4. However, the impact toughness of the specimens in the as-deposited state with the addition of Fe is slightly decreased.
-
Xu Demei, Li Meisui, Li Zhinian, Ye Shupeng, He Lijun, Li Feng
2025,54(12):3192-3202 DOI: 10.12442/j.issn.1002-185X.20240551
Abstract:The microstructure evolution and the static recrystallization kinetics of metal beryllium during annealing at 680–880 ℃ were investigated. The isothermal compression test was conducted on an Instron 5582 testing machine and the recrystallized fraction of metal beryllium under varying strain temperatures (250–450 ℃), strain rates (10–1–10–4 s–1), and true strains (0.16–0.92) was obtained. The results show that decreasing the strain temperature and increasing the strain rate can promote the progress of beryllium recrystallization. As the strain is increased, the beryllium recrystallized grains are refined, and the recrystallization rate is accelerated. However, the effect of increasing the strain on improving the recrystallization rate of beryllium is diminished when the true strain increases to more than 0.60. Increasing the annealing temperature, the recrystallization rate of beryllium is significantly accelerated. In particular, when the annealing temperature is elevated from 750 ℃ to 780 ℃, the recrystallization rate of beryllium enhances dramatically. At 880 ℃, the time for beryllium to complete recrystallization is reduced to approximately 5 min. The static recrystallization activation energy of beryllium is 396.56 kJ·mol–1 at 680–750 ℃, while it is only 72.93 kJ·mol–1 at 780–880 ℃. A static recrystallization kinetic model of beryllium with a modified Avrami component n is constructed. The calculated values of the model are in good agreement with the experimental values, which indicates that the model can accurately predict the static recrystallized fraction of beryllium deformed at 250–450 ℃, meeting the requirements of engineering applications.
-
Application of Nanofibrous LSCF@GDC Composite Oxygen Electrodes in Reversible Solid Oxide Fuel Cells
Sun Xu, Zhang Bingqi, Zhao Jingqi, Sun Yue, Liu Xin, Zhou Hongyang
2025,54(12):3203-3209 DOI: 10.12442/j.issn.1002-185X.20240581
Abstract:Reversible solid oxide fuel cell (RSOFC) can theoretically achieve a relatively high energy conversion efficiency. The key to its widespread application is the increased hydrogen production and output current by further enhancing the current density. However, insufficient catalytic activity of the oxygen electrodes has become an obstacle to the application of RSOFC. The research successfully prepared the composite LSCF@GDC nanofibers with reversible oxygen evolution and reduction electrocatalytic activity synthesized by electrospinning technique. Results show that, compared with the oxygen electrodes materials synthesized by the traditional sol-gel method, the oxygen electrodes with three-dimensional nanofiber structure in this work described greatly reduces the battery polarization impedance, increases the discharge power density and electrolytic current density, and shows better reversibility and stability in long-term tests. This research confirms the advantage of electrode morphology engineering control in expanding the catalytic interface and reaction sites.
-
Jin Jufeng, Zhao Xinbao, Zhao Qianmin, Yue Quanzhao, Gu Yuefeng, Zhang Ze
2025,54(12):3065-3076 DOI: 10.12442/j.issn.1002-185X.20240656
Abstract:GH4350 (AEREX 350) is a Ni-based wrought superalloy for high-performance fasteners, with a maximum service temperature of 750 °C. It has high tensile strength, fatigue resistance, stress rupture and relaxation resistance, corrosion resistance, low thermal expansion, and notch sensitivity. The high strength of GH4350 is largely derived through solid solution strengthening and the γ′ phase precipitation strengthening. During the precipitation of γ′ phase, a minor amount of η phase also precipitates. However, it is reported that the microstructure of alloy is sensitive to heat treatment parameters, including temperature and time. The γ′ phases can be transformed into η phases under certain conditions, potentially degrading the performance of the alloy. The chemical composition characteristics, heat treatment strategies, and strengthening mechanism of GH4350 were reviewed in this research, aiming to understand the factors behind its remarkable high-temperature performance, to guide the development of new alloys, and to further enhance its heat resistance.
-
Luo Jun, Wang Xi, Ding Xianfei, Nan Hai, Liu Changkui, Li Nan
2025,54(12):3210-3217 DOI: 10.12442/j.issn.1002-185X.20240522
Abstract:TiAl alloys have a good application prospect in the field of high temperature structural materials due to their excellent specific strength, specific stiffness, corrosion resistance and oxidation resistance. The lamellar structure is an important microstructure of TiAl alloy, and its discontinuous coarsening behavior directly affects the comprehensive properties of the alloy. In this paper, the coarsening types of TiAl alloy lamellar structure are introduced, and the thermodynamics and kinetics of discontinuous coarsening are analyzed. Besides, the research progress of discontinuous coarsening behavior of TiAl alloys lamellar structure in recent years is reviewed. The effects of chemical composition and content, microstructure characteristics, heat treatment process (such as cyclic heat treatment cycle, temperature, time, cooling rate, etc.), additive manufacturing technology and stress on discontinuous coarsening are summarized. Finally, the future development direction of TiAl alloy lamellar structure design and optimization is prospected.
-
Xu Yaxin, Zou Han, Huang Chunjie, Li Wenya
2025,54(12):3218-3232 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 reinforcement 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.
2025,Volume 54, Issue 12
>Special Issue：High Temperature Alloy
>Materials Science
>Reviews
- Call for Papers
- Published Issue
Volume 54, Issue 7, 2025
Guest Editor-in-Chief: Jiao Yongjun, China National Nuclear Corporation Limited
Guest Editor: Qiu Xi, China Nuclear Power Research Institute
Fang Yonghan, China National Nuclear Corporation Strategic Planning Research Institute Co., Ltd
Shi Minghua, Xi'an Western New Zirconium Technology Co., Ltd
Volume 54, Issue 2, 2025
Guest Editor-in-Chief: Long Weimin
Guest Editor: Sujuan Zhong
2025, Volume 54, Issue 1
2025, Volume 54, Issue 3
2024, Volume 53, Issue 10
Guest Editor: Ma Fei from Xi'an Jiaotong University
Guest Editor: Wu Guosong from Hohai University
2024, Volume 53, Issue 5
Guest Editor: Hu Ping from Xi'an University of Architecture and Technology
2024, Volume 53, Issue 1
Guest Editor: Qiao Jichao from Northwestern Polytechnical University
-
Preparation and Water Cooling Verification of Pin-fin Diamond/Copper Plates for Electronic Packaging
Cao Wenxin, Han Kai, Ye Zhijie, Zhao Kunlong, Su Zhenhua, Yao Tai, Wang Jiandong, Zhao Jiwen, Zhu Jiaqi, Han Jiecai
Available online:July 28, 2025 DOI: 10.12442/j.issn.1002-185X.20250285
Abstract:The issue of thermal management in electronic packaging is one of the important technical bottlenecks hindering the development of integrated circuits. Diamond/copper composites have excellent performance in the field of thermal management, but the difficulty in their complex structure formation leads to very limited applications in the field of water cooling in electronic packaging. In this study, we aimed to enhance the sintering performance between the green body and the composite plate by employing a silver doping strategy, thereby addressing the thermal management challenges in electronic packaging. We fabricated composite base plates and pin-fin type composite base plates and evaluated their application benefits in both indirect and direct water cooling scenarios. Our findings demonstrated that the silver-doped copper billet achieved good sintering performance when combined with tungsten-coated diamond/copper composite plates. The composite base plate and the pin-fin type composite base plate effectively reduced the temperature of the heating sheet by 5-6°C and 4-5°C during water-cooling tests respectively. The numerical simulation results were in good agreement with the experimental data, confirming the excellent thermal uniformity of the composite structures. This study successfully overcame the limitations associated with the low thermal conductivity of traditional packaging components and the challenges in fabricating complex structures using diamond/copper composite materials.
-
Available online:July 17, 2025 DOI: 10.12442/j.issn.1002-185X.20250367
Abstract:Metallic glasses are a unique class of materials with exceptional mechanical properties, including high strength, excellent corrosion resistance, and significant elasticity. These materials display intriguing dy- namical relaxation processes, which influence their mechanical and thermal properties. Understanding the dynamical relaxations in metallic glasses is crucial for optimizing their performance in various applications. Due to the limitations of experimental techniques to access processes at the atomic level, the detailed mechanisms responsible for the dynamical relaxations cannot be easily probed experimentally. Numerical simulations are good candidates to analyze in depth the elementary dynamical processes at the atomic scale and thus to capture the fundamental origin of dynamical relaxations. The development of computing power in the last decades has allowed researchers to reach an enormous advancement in the understanding of the physical mechanisms behind dynamical relaxations in metallic glasses.
-
Zhang Yan Lin, Chen Shuo, Jiang He, Dong Jian Xin
Available online:June 19, 2025 DOI: 10.12442/j.issn.1002-185X.20250173
Abstract:Taking an Inconel 718 (GH4169) turbine disk with an accumulated service time of approximately 60,000 hours from a specific model of aircraft as the research object, this study systematically investigates the microstructure of various regions of the service turbine disk. Detailed characterization of the microstructure was conducted using research methods such as optical microscopy, scanning electron microscopy, electron probe, extraction phase analysis, inclusion scanner, and nano-indentation. The results show that after long-term service, there is no significant change in the strengthening phases γ" and γ" of the turbine disk. However, the quantity, size, and morphology of primary MC carbides from the center to the edge have undergone noticeable decomposition. The content decreased from 0.166 wt.% to 0.106 wt.%, and the morphology gradually changed from sharp and regular blocky shapes at the interface to irregular near-circular shapes. The nano-hardness decreased, and there was a significant redistribution of elements, with Nb, Ti, and C elements released and diffused into the matrix. The primary MC carbides are prone to dissolution and decomposition during long-term service, leading to a decrease in the concentration and hardness of the carbide elements. The diffusion of carbide-forming elements into the matrix may cause a "disturbance" to the comprehensive mechanical properties of the alloy during the long-term service performance.
-
He Miaoxia, Jiang Qing, Guo Yumeng, Dong Yuecheng, Igor V. Alexandrov
Available online:June 19, 2025 DOI: 10.12442/j.issn.1002-185X.20250219
Abstract:In the face of harsh and complex oil and gas resources exploitation environment, it is urgent to explore titanium alloy oil well pipes with high strength and toughness service performance. In this paper, the cross piercing (RP) TC4-0.55 Fe titanium alloy seamless tube was taken as the research object. The microstructure was controlled by solid solution and aging process. The tensile properties at room temperature and impact properties at -20 °C were tested. The effects of microstructure evolution on mechanical properties were analyzed by SEM, XRD and TEM. The results show that the size of αC and the average grain thickness of αL increase significantly, and the orientation and uniformity of the microstructure are also significantly enhanced after the deformed Widmanstatten structure of the RP sample is aged in the two-phase region (STA910). The tensile strength, yield strength and elongation of RP samples are 904 MPa, 793 MPa and 14.2 %, respectively. The impact energy and impact toughness at -20 °C are 66.2 J and 82.7 J/cm2, respectively. After solution and aging in the two-phase region, the tensile strength, yield strength and elongation of STA910 sample increased to 984 MPa, 904 MPa and 16.2 %. The impact energy and impact toughness at-20 °C decreased slightly, but still maintained at 52.8 J and 66.2 J/cm2. The α/β interface is increased by the precipitation of αS and ω phases in the STA910 sample, which increases the dislocation slip and motion resistance and improves the segregation of alloying elements. The dual effects of grain boundary strengthening and solid solution strengthening are achieved, thus improving the strength and plasticity of the alloy. On the other hand, all TC4-0.55Fe alloys show excellent impact toughness. The fracture modes of the alloys are mainly ductile fracture and transgranular fracture. The coarsening of α phase grain size, the decrease of β phase stability and the precipitation of αS and ω phases in βt lead to the decrease of impact properties of the alloys.
-
Wei Lai, Wang Xiaohua, Liu Jie, Wang Yifei, Ma Shengguo, Wang Zhihua
Available online:June 13, 2025 DOI: 10.12442/j.issn.1002-185X.20250166
Abstract:Porous CoCrNi MEA with porosity of 60.6% -78.1% and pore size of 1.8 -2.4mm were prepared by powder sintering-dissolution method. The pore distribution is uniform and the metallurgical bonding is good. The dynamic compression test results show that the material has a significant strain rate strengthening effect, and the impact resistance is the best at 500s-1 strain rate. The yield strength increases by 52.8% (22.9 MPa to 35.0MPa) with the increase of strain rate from 200s-1 to 800s-1. The dynamic yield strength increases by 25% compared with the quasi-static yield strength. The energy absorption value reaches 35.4 ~14.5MJ/m3 (6.6% ~ 14.0% higher than the quasi-static), and the maximum ideal energy absorption efficiency is close to 0.9. At the same time, under the condition of low temperature (-100°C), the elastic modulus and platform stress are increased by 2.4% ~10.5% and 2.5% ~9.8%, respectively, compared with room temperature. The energy absorption value is 41.3 ~15.2MJ/m3, which is twice that of magnesium alloy foam, and the maximum ideal energy absorption efficiency remains 0.8. In summary, the porous CoCrNi MEA has both dynamic strengthening and low-temperature strengthening characteristics, and has good energy absorption capacity and high ideal energy absorption efficiency, showing significant application potential in the field of actual working conditions and extreme environments.
-
ZHANG Lichong, CHEN Hao, LIU Yufeng, ZHENG Liang, XU Wenyong, LI Zhou, ZHANG Guoqing
Available online:June 13, 2025 DOI: 10.12442/j.issn.1002-185X.20250198
Abstract:Electrode Induction Melting Gas Atomization (EIGA) is a crucial technique for producing ultra-high-purity metal powders, as it is a crucible-free powder production method. This study focuses on the nickel-based superalloy FGH96 and the titanium alloy TC4, and investigates the effects of atomization pressure and gas temperature on the particle size, morphology, and hollow powder content of the alloys. The study combines atomization experiments with powder characterization. The results show that at a gas temperature of 25°C, increasing the atomization pressure from 2.5 MPa to 4.0 MPa, reduces the median particle size (D??) from 96.3μm to 75.5μm. The sphericity reaches its maximum value 0.9805 at an atomization pressure of 3.5MPa. The powder volume porosity also exhibits a trend of first increasing and then decreasing. At an atomization pressure of 4.0MPa, as increasing the gas temperature to 100°C the powders further refine, with the D?? values for FGH96 and TC4 powders decreasing to 63.8μm and 86.0μm, respectively. The gas heating effect is more pronounced for the superalloy powders. As the gas temperature rises, the powder sphericity of the superalloy remains unchanged, while the powder sphericity of the titanium alloy increases slightly. The powder volume porosity of the superalloy slightly increases. Due to differences in viscosity, surface tension, and density between the two alloy melts, powder characteristics such as particle size and morphology exhibit distinct variation trends. This study provides a theoretical basis for the customization of powder preparation processes for different types of alloys.
-
Hong Xin, Yan Lizhen, Zhang Yongan, Li Xiwu, Li Zhihui, Wen Kai, Geng Libo, Qi Bao, Li Ying, Xiong Baiqing
Available online:May 09, 2025 DOI: 10.12442/j.issn.1002-185X.20240846
Abstract:Metallographic microscopy (OM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and room-temperature tensile, tearing, and fatigue crack extension experimental methods were used to investigate the effect of the four final cold-rolling deformations （13%、23%、46%、68%） after intermediate annealing on the grain morphology and damage resistance properties of the Al-3.9Cu-0.74Li-0.68Mg alloy sheets. The results indicate that with increasing cold-rolling reduction after intermediate annealing, complete recrystallization occurred in the sheets after solution treatment, leading to a significant reduction in the average grain size and aspect ratio, with grains tending to become more equiaxed. The primary precipitates in the aged alloy were T1 phase, and the size, number density, and volume fraction of T1 phase showed little variation among the four reduction levels. Quantitative calculations of the contributions of different strengthening mechanisms to the yield strength revealed that the strengthening of the alloys with the four reduction levels was mainly attributed to the precipitation strengthening of T1 phase, contributing 336-367 MPa to the yield strength. With increasing cold-rolling reduction, the fatigue crack growth rate of the sheets increased, resulting in deteriorated fatigue performance, while the fracture toughness showed an upward trend. Fine grains were beneficial for improving fracture toughness but detrimental to fatigue property.
-
Yu Shan, WangYuqi, HuangYao, ZhangHexin, ZhaoChengzhi
Available online:May 09, 2025 DOI: 10.12442/j.issn.1002-185X.20240848
Abstract:This study investigates the influence of titanium carbide (TiC) content on the microstructure and mechanical properties of molybdenum (Mo)-based composites, aiming to provide a scientific basis for the development of high-performance, heat-resistant molybdenum materials for aerospace engines. TiC/Mo composites containing 10%, 20%, and 30% TiC were prepared using spark plasma sintering (SPS) technology. The results indicate that the strengthening mechanisms of TiC/Mo composites are primarily attributed to intragranular particle strengthening and grain boundary strengthening. At elevated temperatures, TiC diffuses into the Mo matrix, forming a transition zone of measurable width at the interface of the two phases. XRD analysis confirms that this transition zone comprises (Ti, Mo)C. The crystal lattices of the TiC and Mo phases exhibit strong bonding, which is further corroborated by atomic-scale observations. Tensile and hardness tests reveal that TiC/Mo composites with 10 wt% and 20 wt% TiC demonstrate superior mechanical properties. The fracture behavior of these composites is primarily governed by the propagation of intergranular microcracks, which is influenced by the competition between intergranular and intragranular crack development. This study provides critical insights into the coupling effects of intergranular and intragranular TiC particles on the mechanical performance of TiC/Mo composites.
-
Menghan Wang, Xin Li, Yuanyuan Zheng, Menglong Du, Songlin Li, Haicheng Zhang
Available online:April 03, 2025 DOI: 10.12442/j.issn.1002-185X.20240756
Abstract:Strain uniformity is an important index to evaluate the performance of large disk forgings in aerospace. Taking turbine disc as the research object, this paper explores the reasons for the formation of low strain zone of turbine disc forgings, and proposes a topological optimization design method suitable for large disc forgings based on the addition and removal rule of "number of subunits - volume - number of subunits". The method adopts the allocation of appropriate volume for each column element, and adapts the relative height of each region by stacking and adjusting modules. Obtain the shape of the preforging with low complexity of the target shape. In order to verify the effectiveness of the optimization method, the paper takes deformation uniformity as the goal to automatically optimize the shape of large turbine disc preforging. After optimization, the deformation uniformity of the forging is increased by 45%, and there is no strain dead zone. The results of numerical simulation and production test show the reliability of the method proposed in this paper.
-
Zechen Wu, Kongxun Zhao, Liu Guitao, Kai Liu, Lian Duan, Hongtai Yang, Yitong Liu, Dong Liang
Available online:April 02, 2025 DOI: 10.12442/j.issn.1002-185X.20250014
Abstract:The ZrTiNi system exhibits unique low-temperature melting characteristics and high chemical reactivity potential, offering promising applications in energetic warhead casings. This paper presents a preliminary exploration of the low-temperature liquid phase region of ZrTiNi based on ternary phase diagram calculations. ZrTiNi alloy bulk samples with varying Zr contents (70wt%, 80wt%, and 90wt%) were prepared using a vacuum sintering process, and the materials" microstructure, phase composition, quasi-static mechanical properties, and impact-induced reaction characteristics were studied. According to the phase diagram calculations, the ZrTiNi system has a wide liquid phase region at 900°C, 950°C, and 1000°C, demonstrating significant low-temperature melting characteristics. Relative density and metallographic analysis results show that the Zr70Ti15Ni15 and Zr80Ti10Ni10 alloy samples sintered at 950°C achieved near-full densification, while the Zr90Ti5Ni5 alloy sample had a relative density of only 81.7%, with numerous pore defects remaining in the cross-section. This indicates that as the Zr content increases, the overall melting point of the alloy rises. XRD and SEM analysis results show that the ZrTiNi alloys consist mainly of Zr(Ti) solid solution as the primary phase and Ni-Zr(Ti) intermetallic compounds. Additionally, increasing Zr content promotes the formation of Zr-rich solid solution phases, which inhibits the formation of intermetallic compounds to some extent. Quasi-static compression tests reveal that the densified Zr70Ti15Ni15 and Zr80Ti10Ni10 alloy samples both have compressive strengths exceeding 1200MPa, providing a solid foundation for blast loading resistance and armor-piercing penetration. In ballistic gun tests, the Zr80Ti10Ni10 alloy projectile successfully penetrated the front steel plate at a velocity of 1029m/s and sustained the ignition of jet fuel, demonstrating excellent impact-induced ignition properties.
-
Available online:November 20, 2024 DOI: 10.12442/j.issn.1002-185X.20240434
Abstract:TC4 titanium alloy material will generate significant spring back during the bending process, and its elastic modulus has a significant impact on spring back. However, previous studies have not considered the change in elastic modulus during the plastic strain change process of the material. This study focuses on TC4 titanium alloy and conducts uniaxial tensile and cyclic loading unloading experiments to determine the anisotropy parameters and the variation of material elastic modulus with plastic strain. On this basis, a mathematical model for the variable elastic modulus of TC4 titanium alloy was established. Based on three different constitutive models, namely YLD2000-2D yield criterion and variable elastic modulus, YLD2000-2D anisotropy, and Mises isotropy, numerical simulations were conducted on the five point bending process of TC4 titanium alloy plates at room temperature. In order to verify the numerical simulation results, a five point bending experiment was conducted on TC4 sheets at room temperature. The results showed that the anisotropic constitutive model and the mathematical model of variable elastic modulus significantly improved the prediction accuracy of TC4 titanium alloy bending spring back, the highest prediction accuracy increased by 31.18%.
-
Available online:March 22, 2024 DOI: 10.12442/j.issn.1002-185X.E20230047
Abstract:This study is grounded in thermodynamic phase diagram calculations and employs powder metallurgy techniques to fabricate ultra-coarse grained WC-8(Co,Ni) cemented carbides with varying Ni:Co ratios. The study delves into the alloy"s microscopic structure, mechanical properties and corrosion resistance. It has been shown that carbon equilibrium can be efficiently maintained by using thermodynamic phase diagram calculations, thus preventing the emergence of harmful phases associated with carbon deficiency or excess in the alloy. As the Ni:Co ratio increases, the density of the alloy first increases and then decreases. The average grain size of WC enlarges, leading to a deterioration in the uniformity of the binder phase distribution. This results in a decrease in hardness, an increase in fracture toughness, and an initial rise followed by a significant decrease in flexural strength. Ni plays a crucial role in mitigating the corrosion rate of the binder phase and thus enhancing the corrosion resistance of ultra-coarse grained cemented carbides. When the Ni:Co ratio is 2:6, the alloy demonstrates optimal integrated mechanical properties and its enhanced corrosion resistance is notably pronounced.
-
Zilu Liu, Peng Han, Wen Wang, Qiang Liu, Fengming Qiang, Hairui Xie, Kuaishe Wang
Available online:November 17, 2023 DOI: 10.12442/j.issn.1002-185X.20230255
Abstract:In this paper, the AZ31 magnesium (Mg) alloy coating with antibacterial properties and corrosion resistance was successfully obtained through friction stir processing (FSP) combined with micro arc oxidation (MAO). FSP was firstly utilized to introduce hydroxyapatite (HA) and silver (Ag) particles and prepare the precursor of AZ31 Mg alloy coating. Subsequently, MAO was employed to transfer HA and Ag particles into the surface of Mg alloy, then forming the coating. It is shown that the dispersed HA particles in the precursor promoted the coating growth in the MAO process and increased the thickness of the coatings, improving in the corrosion resistance. The Ag particles with an average size of 2-10 nm refined by FSP were easily to be transferred from the precursors to the Mg alloy coatings during the MAO process, the lower Ag content reduces the corrosion current density of the coating and improves its corrosion resistance. At the same time, the antibacterial performance of the coating has been significantly improved, and the coatings exhibited excellent antibacterial properties with the highest rates of against Staphylococcus aureus and Escherichia coli reaching to 99.4% and 99.6%, respectively.
More++
Online First
The manuscript’s access statistics and the ranking of the number of citations in the year after its publication on the official website
