Abstract:Brazing filler metals are widely applied, which serve as an industrial adhesive in the joining of dissimilar structures. With the continuous emergence of new structures and materials, the demand for novel brazing filler metals is ever-increasing. It is of great significance to investigate the optimized composition design methods and to establish systematic design guidelines for brazing filler metals. This study elucidated the fundamental rules for the composition design of brazing filler metals from a three-dimensional perspective encompassing the basic properties of applied brazing filler metals, formability and processability, and overall cost. The basic properties of brazing filler metals refer to their mechanical properties, physicochemical properties, electromagnetic properties, corrosion resistance, and the wettability and fluidity during brazing. The formability and processability of brazing filler metals include the processes of smelting and casting, extrusion, rolling, drawing and ring-making, as well as the processes of granulation, powder production, and the molding of amorphous and microcrystalline structures. The cost of brazing filler metals corresponds to the sum of materials value and manufacturing cost. Improving the comprehensive properties of brazing filler metals requires a comprehensive and systematic consideration of design indicators. Highlighting the unique characteristics of brazing filler metals should focus on relevant technical indicators. Binary or ternary eutectic structures can effectively enhance the flow spreading ability of brazing filler metals, and solid solution structures contribute to the formability. By employing the proposed design guidelines, typical Ag based, Cu based, Zn based brazing filler metals, and Sn based solders were designed and successfully applied in major scientific and engineering projects.
Nanoflower Copper Sulfide as Cathode Materials for Magnesium Ion Batteries
He Yuantai, Wu Liang, Shi Yongan, Zhong Zhiyong, Yao Wenhui, Pan Fusheng
Abstract:CuS-C50, the cathode materials for magnesium ion batteries, was synthesized by adding the surfactant cetyltrimethyl ammonium bromide (CTAB) and adjusting the percentage of ethylene glycol to 50vol% in hydrothermal synthesis process. Results show that CuS-C50 has the complete nanoflower structure. In aluminum chloride-pentamethylcydopentodiene/tetrahydrofuran (APC/THF) electrolyte, the CuS-C50 exhibits a high specific capacity of 331.19 mAh/g when the current density is 50 mA/g and still keeps a specific capacity of 136.92 mAh/g over 50 cycles when the current density is 200 mA/g. Results of morphology characterizations indicate that the complete nanoflower structure can provide more active sites and reduce the barriers for Mg2+ movement, eventually improving the charge and discharge performance of the CuS cathode materials for magnesium ion batteries.
Interfacial Microstructure and Mechanical Properties of Zr/CoCrFeMnNi HEA Brazed Joints
Du Peng, Song Xiaoguo, Long Weimin, Bian Hong, Qin Jian, Sun Huawei, Jiang Nan
Abstract:AgCu filler was used to braze Zr and CoCrFeMnNi high-entropy alloy (HEA). The effects of brazing temperature and holding time on the microstructure and mechanical properties of the joints were analyzed. The results show that the typical microstructure of the joints brazed at 850 ℃ for 10 min is HEA/Crss/Zr(Cr,Mn)2/Zr2(Co,Cu,Ni,Fe)+Zr2(Ag,Cu)+Zr(Cr,Mn)2/Zr. The joints have the maximum shear strength of 103.1 MPa. As the brazing temperature or holding time rises, the thickness of Cr-rich solid solution and Zr(Cr,Mn)2 layer are increased, the content of Zr2(Co,Cu,Ni,Fe) and Zr(Cr,Mn)2 phase is increased whereas the content of Zr2(Ag,Cu) phase is decreased. Finally, the failure mechanism of the joint was analyzed. Under the action of shear force, as the brazing temperature or holding time rises, the fracture position of the joint shifts from the Zr(Cr, Mn)2 layer to the Zr2(Co, Cu, Ni, Fe) phase fracture in the center of the brazing seam.
Characteristics of Transition Layer at Soft Metal-Substrate Interface for Metal Seal
Zhang Dawei, Zhang Xuekai, Cao Zixuan, Ge Ziyi, Lv Shichang, Li Zhijun, Zhao Shengdun, Hu Yanghu
Abstract:The pressure-actuated metal seal with soft metal coating has been widely used in complex working conditions such as high temperature, low temperature and high pressure. The investigation of the characteristics and binding strength of the transition layer between the soft metal coating and the superalloy substrate is important to improve the sealing performance and to model and simplify the working through-process of metal sealing. The distribution characteristics of elements at soft metal-substrate interface and the binding strength between coating and substrate under different thicknesses and material combinations of coating layer were studied by experimental methods. The results indicate that the thickness of soft metal coating has little influence on the interface morphology of GH4169-Cu, GH4169-Ag and Cu-Ag, but has an influence on the thickness of transition layer between different metals, while this influence is weakened with increasing the coating thickness, and the thickness of transition layer is about 2 μm when the coating thickness is more than 30 μm. The cross-cut test shows that the Cu, Ag and Cu-Ag coatings are all well combined with nickel-based superalloy GH4169 substrate. The materials of soft metal, i.e. the coating materials, have significant influence on the characteristic of transition layer and the surface characteristics of coating after cross-cut test.
Liu Na, Zhao Zhanglong, Liu Yuli, Feng Kaikai, Zha Xiaohui, Li Pu, Xu Wenxin, Yang Haiou, Lai Yunjin
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.
Liu Xianghong, Zhao Ning, Wang Tao, Kang Jiarui, Yang Jing, Li Shaoqiang, Du Yuxuan
Abstract:The sub-stable β-type TB18 titanium alloy exhibits a significant strengthening effect through solutionizing-ageing and possesses excellent potential for achieving a balanced combination of strength and toughness. As a result, it has emerged as a favoured material for manufacturing high-end aviation components. This work aimed to investigate the impact of solid solution treatment on the microstructure and mechanical properties of TB18 titanium alloy. Specifically, the effects of different solution temperatures, solution times, and slow cooling rates after solutionizing on the alloy"s microstructure and mechanical properties were illustrated. The goal is to understand the mechanism behind the interaction between solution treatment and the microstructure-mechanical properties of TB18 titanium alloy. The results indicated that following the solutionizing and aging treatment within the β single-phase region, lamellar and needle-like αs phases precipitated within the β matrix. The presence of lamellar αs phases contributed to the improvement of the toughness of the TB18 titanium alloy. Furthermore, it was observed that the fracture toughness of the TB18 titanium alloy improved with an increase in the thickness of the lamellar αsphases. Elevated solutionizing temperature or prolonged solid solution holding time can result in the coarsening of β grains in TB18 titanium alloy, leading to a decrease in material strength and plasticity. When increasing the cooling rate from 0.25 ℃/min to 1 ℃/min after solutionizing, the fine αs phases uniformly distributed within the TB18 titanium alloy after aging treatment, and the tensile strength increased to 1343 MPa while the elongation was 5 %. By subjecting the TB18 titanium alloy to a solutionizing regime at a temperature of 870 ℃ for 2 hours, followed by air cooling, it achieved a favorable combination of strength and toughness. Further aging at 530 ℃ for 4 hours, again with air cooling, results in a tensile strength of 1315 MPa, yield strength of 1225 MPa, elongation of 8.5%, impact toughness of 29.2 J/cm2, and fracture toughness value of 88.4 MPa . m1/2.
Study of high-temperature oxidation behavior of electrodeposited Ni/Cr coatings on Zr alloy surfaces
Zhu Li''an, Yuan Weichao, Wang Shuxiang, Wang Zhen, Ye Yicong, Bai Shuxin
Abstract:After the Fukushima nuclear accident in Japan, accident tolerant fuel (ATF) cladding technology has attracted widespread attention in the industry. The cladding of Cr coatings on zirconium (Zr) alloys for nuclear fuel cladding in nuclear reactor cores is considered to be the most likely technology to be commercially available in the near future. At present, most of the preparation methods for Cr coatings have the disadvantages of expensive equipment, low deposition rate and weak shape adaptability. And the molten salt electrodeposition technology has the advantages of high cathodic current efficiency, fast electrodeposition speed, and strong adaptability of substrate shape, which is expected to solve the problem of efficient and low-cost preparation of high-quality Cr coatings on the surface of cladding Zr alloys. In order to realize the preparation of Cr coating on the surface of Zr alloy by molten salt electrodeposition, this paper adopted aqueous solution electrodeposition and molten salt electrodeposition methods to prepare Ni transition layer and Cr coating on the surface of Zr alloy substrate sequentially, and carried out the characterization of the organization structure, the bonding force and nano-hardness test as well as the study of the high-temperature oxidation behavior of the Zr/Ni/Cr specimens obtained from the preparation. The results showed that the Ni/Cr coating on the surface of Zr alloy was uniform and dense, and the bonding force between the coating and the substrate was about 151N. The hardness and modulus of elasticity of Zr/Ni/Cr increased gradually from inner to outer layers with a quasi-gradient transition. The surface roughness of the Cr coating was about 2 μm, and the hardness and modulus of elasticity were 2.86 GPa and 172.86 GPa, respectively. The Zr/Ni/Cr specimens showed nearly parabolic and nearly linear patterns during steam oxidation at high temperatures of 1000°C and 1200°C, respectively, indicating that the Ni/Cr coatings were able to provide good protection to the Zr alloy matrix at 1000℃. The high-temperature oxidation failure mechanism of Ni/Cr coatings on Zr alloy surfaces was closely related to the rapid diffusion of the Ni transition layer, the oxidation and diffusion depletion of the Cr layer, and the weakening of the Cr layer due to the rapid diffusion of Zr along the Cr grain boundaries.
Surface Temperature Field of Ti-6Al and Ti-48Al Alloys Under Continuous Laser Ablation
Abstract:The high temperature fire retardancy of titanium alloy is an important factor restricting its application in aero-engine, and the laser ignition method can accurately reflect the fire retardancy of titanium alloy under local heating. Due to the limitations of laser ignition experiments on the microscopic boundary and the transient propagation mechanism of the temperature field, molecular dynamics (MD) simulations and JMatPro calculation were applied to study the temperature field of Ti-6Al and Ti-48Al alloys. The results show that a molten pool is formed on the surface of Ti-Al alloys under continuous laser irradiation, and the temperature field of the molten pool is normally distributed from the center to the edge. When the center temperature reaches the critical point of ignition, the extended combustion occurs, and the extended combustion path advances along the direction of the air flow. Compared with Ti-6Al alloy, Ti-48Al alloy has higher fire retardancy under laser ablation. This is due to the better heat transfer performance of Ti-48Al, which leads to the weakening of the heat concentration effect near the boundary of the spot temperature field. So it is necessary to increase the partial pressure of oxygen, and thus to reduce the ignition point of the alloy in order to achieve the ignition boundary condition of Ti-48Al alloy under the same laser heat source. In the aspect of extended combustion path, the boundary heat collection effect of specimens shown by MD models reveals another mechanism affecting combustion expansion path besides the direction of air flow. That is, the heat generated by the laser spot is interrupted when it is transmitted to the boundary of the specimen along the short side direction, resulting in a concentration of heat near the boundary. So the combustion path also tends to expand along this direction.
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Wang Fanghui, Li Hushan, Zhang Hao, Ding Ziheng, Bao Jianxing, Ding Chaogang, Shan Debin, Guo Bin, Xu Jie
2025,54(5):1121-1126 DOI: 10.12442/j.issn.1002-185X.20240561
Abstract:The effect of deformation resistance of AlCr1.3TiNi2 eutectic high-entropy alloys under various current densities and strain rates was investigated during electrically-assisted compression. Results show that at current density of 60 A/mm2 and strain rate of 0.1 s-1, the ultimate tensile stress shows a significant decrease from approximately 3000 MPa to 1900 MPa with reduction ratio of about 36.7%. However, as current density increases, elongation decreases due to intermediate temperature embrittlement. This is because the current induces Joule effect, which then leads to stress concentration and more defect formation. Moreover, the flow stress is decreased with the increase in strain rate at constant current density.
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Gao Jianping, Lv Yuanjiang, Li Yongjing, Sun Wenqian, Ren Biying, Dai Zhengfei, Ma Fei
2025,54(5):1127-1133 DOI: 10.12442/j.issn.1002-185X.20240720
Abstract:TaN coatings were deposited on Ti bipolar plates by magnetron sputtering to improve corrosion resistance and service life. The influence of N2 flow rate on the surface morphology, hydrophobicity, crystallinity, corrosion resistance, and interfacial contact resistance of TaN coatings was studied. Results show that as the N2 flow rate increases, the roughness of TaN coatings decreases firstly and then increases, and the hydrophobicity increases firstly and then decreases. At the N2 flow rate of 3 mL/min, TaN coating with larger grain size presents lower roughness and high hydrophobicity. The coating possesses the lowest corrosion current density of 2.82 μA·cm-2 and the highest corrosion potential of -0.184 V vs. SCE in the simulated proton exchange membrane water electrolyser environment. After a potentiostatic polarization test for 10 h, a few corrosion pits are observed on the TaN coatings deposited at an N2 flow rate of 3 mL/min. After 75 h of electrolytic water performance testing, the TaN coating on bipolar plate improves the corrosion resistance and thus enhances the electrolysis efficiency (68.87%), greatly reducing the cost of bipolar plates.
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Yang Han, Li Bo, Lu Jinwei, Xu Long, Chen Wanqing, Zhou Wei, Du Yong
2025,54(5):1134-1144 DOI: 10.12442/j.issn.1002-185X.20240228
Abstract:Thermal deformation characteristics of Fe-Cr-Ni-based alloys for nuclear power plants were investigated using a Gleeble-3500 thermal simulation tester. The microstructure evolution law of alloy heat deformation was investigated using the electron backscatter diffraction (EBSD) technique. Results demonstrate that the flow stress curves show typical dynamic recrystallization (DRX) characteristics. According to EBSD analysis, the nucleation and growth of DRX grains are mainly at grain boundaries. The complete DRX occurs at 1100 °C/0.01 s-1 condition, and the grains are refined. The main DRX nucleation mechanism of the alloy is the grain boundary bowing nucleation. Therefore, the softening mechanism of Fe-Cr-Ni-based alloys for nuclear power plants is the combination of dynamic recovery and DRX. The Arrhenius constitutive model with strain compensation is developed. The correlation coefficient between the predicted and experimental values is 0.9947. The reliable mathematical model of critical stress (strain) and Z parameter is obtained. The critical stress (strain) of DRX increases as the temperature decreases or the strain rate increases. The DRX kinetic model is established by the Avrami model, and a typical S-type curve is obtained. As the strain rate decreases and the temperature increases, the volume fraction of DRX increases.
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Bi Guangli, Wei Zhichao, Jiang Jing, Zhang Niuming, Li Yuandong, Chen Tijun
2025,54(5):1145-1155 DOI: 10.12442/j.issn.1002-185X.20240205
Abstract:The effects of the co-addition of Ni and Zn on the microstructure and mechanical properties of the extruded Mg-6.84Y-2.45Cu (MYC, wt%) alloy were researched. Results show that the as-cast Mg-6.79Y-1.21Cu-1.12Ni-1.25Zn (MYCNZ, wt%) alloy consists of the α-Mg, a few Y-rich phases, lamellar 18R-long period stacking ordered (LPSO) phase, and granular Mg2(Cu, Ni, Zn) phase. After the homogenization process, phase transformation occurs in MYCNZ alloy. Some 18R-LPSO phases at the grain boundary are transformed into the thin striped 14H-LPSO phase in the grains. After extrusion, the amount, morphology, and distribution of the second phase are changed, and the grain size of the extruded MYCNZ alloy is significantly reduced to approximately 2.62 μm. Additionally, a weaker basal texture is formed in the extruded MYCNZ alloy. The tensile results indicate that the co-addition of Ni and Zn significantly enhances the tensile strength of the extruded MYC alloy while maintaining good ductility. The tensile yield strength (σ0.2), ultimate tensile strength (σb), and elongation to failure (εL) of the extruded MYCNZ alloy are 266.9 MPa, 299.8 MPa, and 20.1%, respectively. This alloy has a good strength-plastic synergistic effect. The excellent tensile strength of the extruded MYCNZ alloy at room temperature is mainly due to grain refinement and the second phase strengthening effect, and its outstanding ductility is ascribed to the texture weakening and activation of non-basal slips.
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Wang Pengjia, Ma Yuning, Peng Baoying, Lin Kun, Li Xiaobing, Liu Kui
2025,54(5):1156-1164 DOI: 10.12442/j.issn.1002-185X.20240554
Abstract:First-principles theory calculations were used to investigate the segregation behavior of P and Mg as well as the interactions between Mg and P at α-Fe Σ3(111)
symmetrical tilt grain boundary (GB). Results demonstrate that both P and Mg are segregated at GB, and P has a stronger segregation potency. Mg prefers to substitute at grain boundary plane with the largest absorbable vacancy, whereas P inclines to substitute at the sites near Fe atoms to form strong covalent Fe-P bonds. When Mg exists at GB, the segregation behavior of P may be greatly inhibited by the decrease in possible solution sites and the increase in segregation energy. P has stronger interactions with Mg at GB, forming a lower energy hybridization peak. These results can be used to explain why the addition of a small amount of Mg can ameliorate the temper embrittlement phenomenon. -
LiSuli, Fan Longfei, Chen Jichao, Gao Zhuang, Xiong Jie, Yang Laixia
2025,54(5):1165-1176 DOI: 10.12442/j.issn.1002-185X.20240225
Abstract:To overcome the shortage of complex equipment, large volume, and high energy consumption in space capsule manufacturing, a novel sliding pressure Joule heat fuse additive manufacturing technique with reduced volume and low energy consumption was proposed. But the unreasonable process parameters may lead to the inferior consistency of the forming quality of single-channel multilayer in Joule heat additive manufacturing process, and it is difficult to reach the condition for forming thin-walled parts. Orthogonal experiments were designed to fabricate single-channel multilayer samples with varying numbers of layers, and their forming quality was evaluated. The influence of printing current, forming speed, and contact pressure on the forming quality of the single-channel multilayer was analyzed. The optimal process parameters were obtained and the quality characterization of the experiment results was conducted. Results show that the printing current has the most significant influence on the forming quality of the single-channel multilayer. Under the optimal process parameters, the forming section is well fused and the surface is continuously smooth. The surface roughness of a single-channel 3-layer sample is 0.16 μm, and the average Vickers hardness of cross section fusion zone is 317 HV, which lays a foundation for the subsequent use of Joule heat additive manufacturing technique to form thin-wall parts.
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Wen Guodong, Wang Shiqing, Zhang Suhui, Qi Junlei, Chen Haiyan, Wang Xingxing, Xu Dong
2025,54(5):1177-1184 DOI: 10.12442/j.issn.1002-185X.20240207
Abstract:Polycrystalline diamond compact (PDC) cutters and carbon steel were brazed by AgCuInTi filler metal under vacuum condition. The effects of brazing temperature on the wettability of base metal and shear strength of joints were investigated. Besides, the joint's interface microstructure, composition, and phases were analyzed. Results show that the AgCuInTi filler metal exerts a good wetting effect to the surface of cemented carbide and steel. With the increase in brazing temperature, the wetting angle decreases and the spreading area increases. The suitable temperature for vacuum brazing of PDC cutters is 770 °C, and the maximum shear strength is 228 MPa at this temperature.
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Luo Hengjun, Deng Hao, Yuan Wuhua, Liu Wenhao, Chen Longqing
2025,54(5):1185-1193 DOI: 10.12442/j.issn.1002-185X.20240192
Abstract:The effect of holding time of double annealing process on the microstructure and mechanical properties of Ti-5Al-5Mo-5V-1Cr-1Fe (Ti55511) alloy was investigated.Results reveal that the shape and size of the primary α (αp) phase are predominantly influenced by the holding time at the first stage. With the prolongation of holding time, the long strip of αp is transformed into a short rod due to the terminal migration mechanism, leading to the broadening growth, and the growth of αp slows down when the holding time is over 2 h. The volume fraction of αp is mainly affected by the holding time of the second stage: with the prolongation of holding time, the volume fraction of αp is increased, which is accompanied by the precipitation of the secondary α (αs). The mechanical properties of Ti55511 alloy are influenced by both αp and αs. Tensile results indicate that the optimal holding time of double annealing is 1–4 h for the first stage and 0.5–2 h for the second stage.
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Zhang Lei, Huang Bensheng, Xie Chuandi, Chen Gen, Du Jiao, Sun Haishen, Zuo Hanyang
2025,54(5):1194-1206 DOI: 10.12442/j.issn.1002-185X.20240198
Abstract:Powder metallurgy was used to fabricate TiC-NiCr cermets and the oxidation behavior at 900 °C was investigated. Results reveal that TiC-NiCr cermets have uniform structures with excellent mechanical properties, whose hardness is 65 HRC and flexural strength is 1450 MPa. The high-temperature oxidation mechanism of TiC-based cermets was investigated through an X-ray diffractometer and scanning electron microscope. The added elements Ni and Cr along with their solid solutions not only bond with the hard phase TiC to ensure the physical performance of the cermet, but also impede the internal diffusion during oxidation by forming a dense composite oxide layer, thereby enhancing the oxidation resistance. The TiC-NiCr cermet exhibits a dense protective oxide layer at 900 °C and can endure continuous oxidation for approximately 1000 h. A methodology for fabricating TiC-NiCr metal matrix composites is proposed, and their oxidation resistance is evaluated, providing a theoretical and practical basis for simultaneously enhancing the mechanical properties and oxidation resistance and reducing production costs.
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Guo Peimin, Shen Yaozong, Wang Lei, Kong Lingbing, Wang Dongxin, Guo Qing
2025,54(5):1207-1216 DOI: 10.12442/j.issn.1002-185X.20240130
Abstract:A transformative beryllium metallurgy theory and method was proposed based on the low-temperature dissociation of hydrofluoric acid and purification by exploiting the large difference of fluoride solubility. Hydrofluoric acid can quickly dissociate beryllium ore powder directly at low or room temperature with more than 99% dissociation rate. The solubility of AlF3, FeF3, CrF3, and MgF2 is low. Coupled with common ion effect, 99.9%-purity beryllium products can be prepared without chemical purification. For high-purity beryllium products of grade 4N or higher, they can be prepared through the superior property that the pH intervals of iron, chromium, and other hydroxide precipitates are distinctly different from those corresponding to Be(OH)2 precipitates. This new method can be used to prepare most of the beryllium products that are prepared by modern beryllium metallurgy.
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Zheng Yongfeng, Hu Xiaofeng, Yang Zhirong, Jiang Haichang, Rong Lijian
2025,54(5):1217-1228 DOI: 10.12442/j.issn.1002-185X.20230827
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 ℃.
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Huang Danlan, Xue Jianing, An Ning, Wu Yajing, Shi Feng, Cao Hehuan, Yang Fan, Li Chongyang
2025,54(5):1229-1234 DOI: 10.12442/j.issn.1002-185X.20230817
Abstract:Due to the large proportion of the inclusions, it''s hard to remove the inclusions such as hafnium oxide in the cast superalloy containing hafnium. In this research, DZ125 superalloy revert was melted by high energy electron beam to remove refractory inclusion, and the composition, microstructure and distribution of slag collected from different positions after electron beam melting were analyzed. The results show that the surface of the final zone of the ingot mainly contains large-sized oxide inclusions and MC carbides, no oxide inclusions are found in different positions inside the ingot, and large-sized HfO2 is found in the slag in the hearth. The high energy electron beam has a stirring effect on the molten pool, which makes a large number of HfO2 and Al2O3 gather together and float to the surface of the ingot under the action of the electron beam, so the refractory oxide inclusion in the revert can be effectively removed.
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Yao Bibo, Peng Yuyang, Li Zhenhua, Liu Meihong, Li Hai, Wang Cong
2025,54(5):1235-1244 DOI: 10.12442/j.issn.1002-185X.20230818
Abstract:Increasing the layer thickness can significantly improve the preparation efficiency of selecting laser melting formed Ti-6Al-4V. However, it leads to lower forming quality in comparison to the alloy with low layer thickness. Annealing heat treatment can improve the ductility of titanium alloy prepared by selective laser melting, but the effect of annealing heat treatment on the sample with high layer thickness is not clear. In this research, the Ti-6Al-4V with high layer thickness was fabricated by selective laser melting. The 700 and 950 ℃ were set as annealing heat treatment temperatures, and the effects of heat treatment on the microstructure and properties of Ti-6Al-4V were investigated. The results reveal that the preparation of samples can achieve good forming quality when the scanning speed ranges from 600 mm/s to 800 mm/s. After annealing at 700 and 950 ℃, the microstructure of the samples transforms from acicular martensite to lath martensite. The β phase can be observed after heat treatment at 950 ℃. The changes in compression performance are influenced by the microstructure. The ultimate compressive strength of the prepared sample with a scanning speed of 600 mm/s is 1593 MPa, and the maximum fracture strain is 15.1%. After annealing heat treatment, the ultimate compressive strength decreases to 1359 MPa and the maximum fracture strain increases to 22.2%. The fracture mode changes from brittle fracture to ductile-brittle fracture.
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Meng Shuaiju, Zhang Mingchi, Wang Menglu, Song Jinlong, Zhang Chaohuan, Bi Guangli, Liu Haifeng, Jia Zhi
2025,54(5):1245-1253 DOI: 10.12442/j.issn.1002-185X.20230815
Abstract:To reveal the effect of Zn element on the microstructure and mechanical properties of Mg-Bi-Sn alloy, Mg-3Bi-5Sn-xZn (x=0, 1, 2, 3, wt%) alloys were prepared by casting. Using OM, SEM, XRD, EPMA, Vickers hardness tester and tensile testing machine, the effect of Zn element on the microstructure and mechanical properties of Mg-3Bi-5Sn (BT35) alloy was studied. The experimental results show that Zn element can significantly reduce the grain sizes of BT35 alloy. With the increase in Zn content, the grain size of BT35 alloys decreases significantly at first and then increases slightly, among which Mg-3Bi-5Sn-2Zn (BTZ352) alloy has the smallest grain size (58.2 μm). In addition, there are two kinds of second phases, Mg3Bi2 and Mg2Sn, observed in BT35 alloys, and additional Mg2Zn phase and BiSn phase can be detected in the microstructure after adding Zn element. When the addition of Zn element is less than 3wt%, the tensile strength and elongation of the alloy firstly increase and then decrease slightly. Among them, BTZ352 alloy shows the best mechanical properties with the tensile strength and elongation of 263.5±6.0 MPa and 13.2%±0.6%, respectively; and the fracture microstructure of BTZ352 alloy exhibits typical transgranular fracture characteristics.
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Ning Zhaoyong, Xin Shewei, Zhou Wei, Wang Xiao
2025,54(5):1254-1260 DOI: 10.12442/j.issn.1002-185X.20230828
Abstract:The microstructure of Ti-1500 alloy in three deformation zones at different hot upsetting temperatures was comparatively analyzed through hot upsetting experiments. The results show that the hot upsetting process has a significant influence on the microstructure evolution, and the higher the hot upsetting temperature and the larger the deformation degree, the more obvious the regional dynamic recrystallization. Specifically, dynamic recrystallization does not occur in deformation zone Ⅰ and deformation zone Ⅱ at 700 ℃, but obvious recrystallization occurs in deformation zone Ⅲ, α→β phase transformation occurs at 820 ℃, obvious dynamic recrystallization occurs in all three deformation zones, and the recrystallized grains grow excessively at 900 ℃. During upsetting at 700 ℃, the {001}//ND texture is formed in the deformation zone Ⅰ. With the increase in deformation degree, the direction of grains in the deformation zone Ⅱ gradually changes to the directions of <001> and <111>, finally the {001} texture with higher strength and more volume fraction is formed, and a part of the {111}//ND texture is formed. When the deformation amount increases and influences the deformation zone Ⅲ, recrystallization forms new grains with <001> orientation, and the boundaries of <001> oriented grains migrate to those of <111> oriented grains, which leads to the further increase of {001} texture strength and volume fraction, while the volume fraction of {111} texture decreases. And the texture type, texture strength and texture evolution law at 820 and 900 ℃ are consistent with those at 700 ℃.
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Li Shu, Zhao Zhan, Jiang He, Dong Jianxin
2025,54(5):1261-1272 DOI: 10.12442/j.issn.1002-185X.20230832
Abstract:This study investigated the complex evolution of precipitates during the solidification of high-carbon nickel-based superalloy ingots, exploring the relationship between phase transformation and hot cracking sensitivity during solidification. The causes of hot crack sensitivity in ingots were identified using optical microscopy, scanning electron microscopy, and thermodynamic calculations. Differential scanning calorimetry and isothermal solidification experiments, combined with various structural analysis methods, were used to reveal the impact of phase transitions on hot crack sensitivity during solidification. The essence of high hot crack sensitivity due to the evolution of alloy solidification structure and its impact on mechanical properties were elucidated through zero-strength and zero-plasticity tests during solidification, along with thermal stress analysis. The solidification of the alloy produces complex precipitate phases. The significant enrichment of elements like Al, C, Ti, Co, Ni, Nb, and Mo in the liquid phase results in the formation of Laves phase and (γ+γ′) eutectic phase at lower temperatures. This leads to a slower rate during the final stage of solidification, with a solidification temperature range up to 151 ℃. The first principal stress experienced by ingots in the brittleness temperature range is influenced by the ingot size and casting process. The stress often exceeds the strength limit of the alloy, indicating a high tendency for hot crack in the alloy. This reveals the relationship between the solidification process of superalloy and the toughness and strength of the ingot, providing theoretical and practical guidance for controlling the tendency to crack during solidification.
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Xu Yangtao, Peng Yin, Du Haiyang, Li Yanhong, Zhong Zhiqiang
2025,54(5):1273-1282 DOI: 10.12442/j.issn.1002-185X.20230839
Abstract:This study investigated the effect of different concentrations of cerium sulfate Ce2(SO4)3 on the grain refinement of nickel deposition layers during the electrochemical deposition process in industrial electrolytes. The impact of different Ce2(SO4)3 concentrations on nickel electrodeposition behavior was analyzed using the linear sweep voltammetry (LSV) curve, cyclic voltammetry (CV) curve and chronoamperometry (CA) curve. The microstructure morphology and grain size of the deposition layers were analyzed using scanning electron microscopy and the preferred orientation and crystal structure were analyzed using X-ray diffraction. The results show that the addition of different concentrations of Ce2(SO4)3 to the industrial electrolyte leads to a negative shift in the starting deposition potential of nickel, an increase in cathode polarization degree, an increase in overpotential, a shortened nucleation relaxation time tm and an accelerated nucleation rate during nickel electrodeposition, resulting in grain refinement of the deposition layers. However, the addition of Ce2(SO4)3 does not modify the nucleation mechanism of nickel electrocrystallization, nor does it change the crystal structure of the nickel deposition layer, which still remains a face-centered cubic (fcc) structure. When 0.6 g/L Ce2(SO4)3 is added, the grain growth orientation is transformed from the (111) plane to a bidirectional preferred growth of the (111) and (220) planes. At this point, the grain distribution in the deposition layer is uniform, and the grains undergo obvious refinement.
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Zhang Zhongke, Ji Baocheng, Chen Rongyao, Liu Lina
2025,54(5):1283-1290 DOI: 10.12442/j.issn.1002-185X.20230841
Abstract:Plasma welding technique was used to weld the nickel based superalloy Inconel 625 plate (100 mm×50 mm×4 mm) with yttrium (Y) metal powder. The samples were characterized by OM, SEM and mechanical properties test. The results show that the joint formation is optimal when the welding current is 95 A, the welding speed is 110 mm/min, the plasma gas flow is 3 L/min and the content of yttrium element is 0.3wt%. The microstructure of the weld zone is fine equiaxed crystal, and the finer and more uniform grains appear in the heat affected zone after adding yttrium element. A large amount of Laves phase, carbide phase (MC) and yttrium-rich phase (Y-riched) are precipitated in welded joints. With the increase in yttrium content, the tensile strength, yield strength and elongation of the joint increase first and then decrease. When the yttrium content is 0.3wt%, the tensile strength of the sample is the highest of 776.59 MPa, the yield strength is the highest of 595.68 MPa, and the elongation is the highest of 46.60%. The overall property of the sample is higher than that without adding rare earth. Both tensile and impact fractures are ductile fractures. When the yttrium content is 0%, the hardness of weld zone is the highest, and the hardness of weld zone decreases significantly after the addition of yttrium element.
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Wang Wei, Luo Chicheng, Jiang Li, Liu Dan, Xin Shewei, Yu Chengcheng
2025,54(5):1291-1298 DOI: 10.12442/j.issn.1002-185X.20240009
Abstract:The microstructure characteristic parameters of TC11 titanium alloy during different heat treatments were quantitatively investigated, aiming at the lack of quantitative relationship between microstructure characteristic parameters and room temperature tensile properties of TC11 titanium alloy. The content of equiaxed α phase, grain size of equiaxed α phase, thickness of platelet α phase and aspect ratio of platelet α phase at different heat treatment temperatures were quantitatively characterized using image analysis software. Quantitative relationships among heat treatment temperature, quantitative microstructure parameters and room temperature tensile properties were established. And quantitative relationships between quantitative microstructure parameters and room temperature tensile properties were analyzed using a multivariate nonlinear regression model. The results indicate that the microstructure of TC11 titanium alloy depends on the heat treatment regime. For every 10 ℃ increment in solid solution temperature, the content of the equiaxed α phase decreases by about 4.6%. For every 10 ℃ increment in aging temperature, the thickness of platelet α phase increases by about 0.05 μm. Experimental and statistical analyses show that with the decrease in the content of the equiaxed α phase, the strength of TC11 titanium alloy firsthy decreases and then increases, and the plasticity firsthy increases and then decreases. The grain size of the equiaxed α phase has a small effect on the room temperature tensile properties of the alloy. The increase in platelet α phase thickness increases the strength of the alloy. The correlation between alloy plasticity and platelet α phase thickness ia relatively small. With the decrease in the aspect ratio of platelet α phase, the strength of the alloy firstly decreases and then increases, and the plasticity increases. The relationship between microtissue characteristics and room temperature tensile properties conform to the multivariate monlinear regression model.
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Yang Jingyu, Su Jie, Tan Liming, Liu Feng, Li Qianyi, Yu Shiya, Hao Xin, Zhang Longfei, Ma Xin, Yi Chushan, Liu Yong, Huang Lan
2025,54(5):1299-1306 DOI: 10.12442/j.issn.1002-185X.20240022
Abstract:The microstructure and properties of K4169 alloy after hot isostatic pressing (HIP), HIP+homogenization+solution aging (N1) and homogenization+HIP+solution aging (N2) were investigated. Results show that after HIP, the Laves phase is transformed into carbides, and the dendritic segregation and pore defects are eliminated. The γ″ strengthening phase sizes of N1 and N2 samples are 70.71 and 106.76 nm, respectively. The N2 sample precipitates a large amount of δ phase due to the enrichment of element Nb at the grain boundary after HIP. The HIP process improves the tensile properties of K4169 alloy at room temperature and 700 ℃. The rupture life of N1 and N2 samples at 650 ℃/620 MPa is 205.88 and 36.87 h, respectively. In the tensile test, the carbide is broken into micropores due to stress concentration, and the cracks are initiated and propagated from the micropores. In the creep rupture test, the crack is propagated along the grain boundary, and the precipitated δ phase is separated from the matrix under the action of stress to produce micropores, thus weakening the grain boundary and reducing the creep rupture property of the alloy.
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Qian Zhihui, Zhu Qin, Ma Jiao, Tao Yang, Guo Yujiao, Lu Yao, Ning Ping, Guo Junming
2025,54(5):1307-1316 DOI: 10.12442/j.issn.1002-185X.20240034
Abstract:The rapid capacity decay of spinel LiMn2O4 is attributed to the occurrence of Jahn-Teller distortion and Mn dissolution, which restricts commercial application. Herein, a low temperature solid state combustion method was employed to synthesize various LiAl0.03CoxMn1.97-xO4 (x≤0.08) cathode materials. The results show that Al-Co co-doping reduces the surface energy barrier of truncated octahedral {111}, {100} and {110} crystal faces, increases the heterogeneous nucleation, promotes the development of truncated octahedral crystals, reduces Mn dissolution and widens the Li+ diffusion channels. The optimal LiAl0.03Co0.03Mn1.94O4 cathode material has a single-crystal particle morphology of completely truncated octahedron and its average Mn valence increases from +3.5 to +3.545, thereby effectively inhibiting Jahn-Teller distortion, stabilizing the crystal structure, and improving the high-rate performance and long-cycle life of the material. At 5 and 10 C, it delivers the first discharge capacities of 108.6 and 104.9 mAh/g with the high capacity retentions of 70.4% and 75.5% after 2000 long cycles, respectively. At a higher rate of 20 C, it shows a low-capacity fade of 9.3% after 500 cycles. The LiAl0.03Co0.03Mn1.94O4 material has a low apparent activation energy (22.84 kJ/mol) and a relatively high Li+ diffusion coefficient (5.47×10-16 cm2/s), indicating that it has a good lithium-ion migration kinetics.
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Tang Qian, Liu Jide, Zhang Hui, Li Jinguo
2025,54(5):1317-1327 DOI: 10.12442/j.issn.1002-185X.20230833
Abstract:To elucidate the reaction mechanism between the nickel-based superalloy melt containing and Al2O3 rare earth elements Y La ceramic crucible during the preparation process of components, in-situ drop-solution method was employed to study the interface reaction between the superalloy melt containing Y and La and the Al2O3 ceramic crucible at 1550 ℃. Results indicate that following the occurrence of interface reactions between the superalloy melt containing rare earth elements and the Al2O3 ceramic crucible, the surface quality of the alloy is favorable, with almost no adhesion of reaction products. When the alloy contains only Y, Y element reacts with Al2O3 to produce intermediate product Y2O3, which subsequently continues to react to form Y3Al5O12. Additionally, a small amount of Hf element reacts with Al2O3 to generate HfO2. When the alloy contains only La, La element reacts with Al2O3 to generate LaAlO3. La element inhibits the participation of Hf element in the interface reaction, and there is no generation of HfO2. However, when the alloy simultaneously contains Y and La, due to the higher reactivity of Y element, Y preferentially reacts with Al2O3 over La element, forming Y3Al5O12. As a result, the reaction between La element and Al2O3 is suppressed, effectively reducing the burning loss of La element.
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Rong Wan, Chen Anqi, Liu Jianfei, Zhang Bowei, Cao Qigao, Wu Junsheng
2025,54(5):1328-1334 DOI: 10.12442/j.issn.1002-185X.20240035
Abstract:In this experiment, CoFeZn layered double hydroxide (LDH) was grown on the surface of foam nickel by hydrothermal method with metal nitrate as the metal source, urea as the precipitator, and ammonium fluoride as the structure directing agent. LDH (D-CoFeZn) with Zn2+ vacancy defect was obtained by alkaline etching. The effects of alkaline etching treatment and Zn content on the performance of electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were analyzed using a three-electrode system in 1 mol/L KOH aqueous solution. The results of morphology and structure show that both CoFe and CoFeZn LDHs are smooth nanorods, and alkaline etching results in the growth of smaller-sized nanosheets on the surface of CoFeZn LDH, but the valence states of the surface elements barely change. The electrochemical results show that Zn2+ vacancy defects greatly enhance the HER and OER performance of the electrocatalyst. The optimized D-CoFeZn-1 can achieve a current density of 100 mA·cm-2 at only 224 mV for the HER and 236 mV for the OER, making it suitable for the all water electrolysis and superior to commercial catalysts in performance.
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2025,54(5):1335-1343 DOI: 10.12442/j.issn.1002-185X.20240104
Abstract:Using high-purity tungsten powder and amorphous boron powder as raw materials, high-purity W2B alloy powder was efficiently synthesized at low temperatures by mechanical activation combined with reactive synthesis. The effects of mechanical activation time on the morphology, particle size distribution, and specific surface area of the powders were investigated, and the relationship among phase composition, synthesis temperature, and reaction mechanism was elucidated. The results indicate that mechanical activation can effectively refine the particles, and the surface area and dislocation density of the powder increase with the prolongation of the mechanical activation time. The content of the W2B phase in the reaction-synthesized powder increases as the mechanical activation time increases. After 20 h of mechanical activation, the true density of the reaction-synthesized powder reaches 17.01 g/cm3, with the W2B phase content of 96wt%. This powder contains 23wt% more W2B phase compared to the powder without the mechanical activation reaction. During the reactive synthesis, the B atoms diffuse into the W matrix, resulting in the formation of the low-density WB phase. Mechanical activation introduces a significant number of dislocation defects, which creates a channel for atom diffusion and accelerates the transformation from the WB phase to the W2B phase.
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Chen Yu, Wang Wentao, Wu Yun, Han Leilei, Wang Ming, Chen Jiajun, Zhao Yong
2025,54(5):1344-1352 DOI: 10.12442/j.issn.1002-185X.20240041
Abstract:REBa2Cu3O7-x(YBCO) high-temperature superconducting coated conductors (CCs), i.e. the second-generation high-temperature superconducting tapes, with excellent current carrying properties and mechanical behavior, are potentially applied in the fields of power, transportation, medical care, and military, receiving extensive attention from superconductor research teams in recent years. Increasing the thickness of the superconducting layer in CCs is facilitated to enhance the superconducting current transmission capability and to increase the engineering critical current density, thus being one of the major routes to reduce the cost of CCs. The "thickness effect", i.e. the critical current density (Jc) decreases with the increase in film thickness, mainly hinders the fabrication of high-quality superconducting thick films. This study introduced the preparation methods and epitaxial growth mechanism of YBCO thick films, discussed various factors that affect Jc and main ways to improve Jc, and summarized the latest research progress of YBCO thick films from major international teams.
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Zhang Gang, Tian Zhuoyuan, Shi Yu, Fan Ding
2025,54(5):1353-1366 DOI: 10.12442/j.issn.1002-185X.20240801
Abstract:NiTi shape memory alloy has a great potential application in aerospace and biomedical fields due to its excellent shape memory effect, superelasticity effect, good corrosion resistance and biocompatibility. However, the poor processability and weldability restrict its application. Selective laser melting as an advanced rapid forming technique can achieve integrated near-net shape formation of alloy parts, which is very suitable for the low-cost and rapid manufacturing of nickel-titanium alloy components with complex structures. In this paper, the research progress on the property control of NiTi alloys via the selective laser melting technique was summarized, and the influential factors and adjustment strategies of the phase transition behavior, mechanical properties and functional properties as well as the failure mechanism of NiTi shape memory alloy were also stated. Furthermore, the challenges and future research orientations of the NiTi alloy fabrication were prospected, providing reference for the life safety and health, and promoting the rapid development of medical-industrial interdisciplinary.
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Li Minggang, Wang Genshen, Sun Dewang, Lu Binghu, Guo Xueyi
2025,54(5):1367-1376 DOI: 10.12442/j.issn.1002-185X.20240039
Abstract:Silver-coated copper powder is a composite material in which silver is coated on the surface of copper. It has the potential to replace silver powder for making pastes, thus cost can be reduced. This paper described the preparation methods of silver-coated copper powder, including mechanical ball milling, melt atomization and chemical plating. Chemical plating has the advantages of simple equipment and low cost, and has become the most widely used method in industry. The principle and process of chemical plating were introduced, and the differences between displacement method and reduction method were compared. Furthermore, the coating mechanism of silver-coated copper powder was summarized. This paper also introduced the applications and progress of silver-coated copper powder in the fields of conductive adhesives, electromagnetic shielding coatings and conductive inks. The technical challenges of silver-coated copper powder were identified, the control model of thickness of coating layer was needed to reduce silver content while maintaining high oxidation resistance. This review can provide guidance for the preparation method and give a deep understanding on the coating mechanism of silver-coated copper powder.
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Liu Zeyu, Hu Jiaqi, Wang Shuai, Ye Jianlin, Liu Lu, Guo Yangyang, Li Hao, Zeng Rongchang, Ren Lingbao, Shan Zhiwei
2025,54(5):1377-1396 DOI: 10.12442/j.issn.1002-185X.20250029
Abstract:Magnesium alloys hold tremendous potential for applications in automotive lightweighting, with reliable joining being one of the key technical issues for lightweight manufacturing. Laser welding is a suitable joining technology for the development of magnesium alloys due to its low heat input. However, the insufficient in-service performance for laser-welded joints of magnesium alloys, currently restricts their engineering applications. This paper summarizes the cutting-edge research progress in laser welding of magnesium alloys, with a focus concentrated on the intrinsic characteristics of laser welding of magnesium alloys and the influence of welding process parameters on the quality of welded joints. Meanwhile, taking into consideration the critical issues found in the cases of magnesium alloys for automotive utilization, the core influencing factors, regarding the service performance of laser-welded joints of magnesium alloys for automotive applications, are reviewed, and the prospect for future development is proposed.
2025,Volume 54, Issue 5
>Materials Science
>Reviews
- Call for Papers
- Published Issue
Volume 53, 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
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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.
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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.
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wangxueli, lifuguo, jiapenglai, zhangzhimin, wangqiang
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240576
Abstract:The digital image correlation (DIC) technology has been used to track promptly the strain distribution and local strain evolution under different strain rates in this paper, and the propagation behavior of strain distribution and its strain rate sensitivity have been investigated. And the electron backscatter diffraction (EBSD) has been selected to analyze the microstructure evolution, the distribution of stress induced α" martensite transformation (SIMT) and martensite twinning after deformation. Besides, the scanning electron microscope (SEM) has been adopted to observe the fracture morphology of the material. The following conclusions can be drawn: (1) The strain distribution evolved from an approximate uniform distribution to a non-uniform distribution, then showing a phenomenon of strain concentration, and ultimately occurring fracture in the strain concentration area, and the significanted necking phenomenon has been displayed at the low strain rates. (2) A clear double yield phenomenon has been exhibited in the stress-strain curves with producing higher strain hardening rates at the low strain rates, it means that the materials show a negative strain rate sensitivity effect. (3) The content of α" martensite increased significantly, the grain size refined obviously, and the average values of KAM (Kernel average misorientation) and GNDs (Geometrically necessary dislocations) increased dramatically with the strain rate decreasing, it indicates that the SIMT increase can contribute to the accumulation of dislocation density in the deformed sample and be more conducive to the coupling effect of multiple plastic deformation mechanisms. (4) The fracture morphology mainly occur tensile fracture by the aggregation of ductile dimples and voids. The stress on the dimples rapidly develops from unidirectional tension to triaxial tension resulting in sufficient growth of the dimples during the deformation process. Therefore, the ductile fracture characteristics dominated in the low strain rates deformation with promoting the occurrence of this phenomenon.
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Sun Xu, Zhang Bingqi, Zhao Jingqi, Sun Yue, Liu Xin, Zhou Hongyang
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240581
Abstract:Reversible solid oxide cells (RSOCs) can theoretically achieve a relatively high energy conversion efficiency. The key to its widespread application is to further enhance the current density so as to increase hydrogen production and output current. However, insufficient catalytic activity of the oxygen electrodes has become an obstacle to the application of reversible solid oxide cells. The paper successfully fabricates composite LSCF@GDC nanofibers with reversible oxygen evolution and reduction electrocatalytic activity by employing electrospinning technology. Compared with the oxygen electrodes materials synthesized by the traditional sol-gel method, the three-dimensional nanofiber structure oxygen electrodes 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. The research confirms the advantage of electrode morphology engineering control in expanding the catalytic interface and reaction sites.
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Gao Yubi, Wang Xin, Zhen Bing, Xu Jiayu, Ding Yutian
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240588
Abstract:The influence of microstructure with different ratios of twin boundaries on the corrosion behavior of GH3625 alloy pipes in high-temperature (600 ℃~800 ℃) KCl-MgCl2 molten salt was studied using EBSD, XRD, SEM, and EDS methods. The results showed that with the increase of annealing temperature, the proportion of annealing twin boundaries in the equiaxed grains of GH3625 alloy tube increased, and the higher the proportion of twin boundaries in the alloy at the same corrosion temperature, the better its high-temperature resistance to KCl-MgCl2 molten salt corrosion. Meanwhile, as the corrosion temperature increases, the high-temperature resistance of the same group of samples to KCl-MgCl2 molten salt corrosion decreases. In addition, under the same grain size conditions, the higher the proportion of annealing twin boundaries in GH3625 alloy tubes, the better their high-temperature resistance to KCl-MgCl2 molten salt corrosion. This is mainly attributed to the high-density stable annealing twin boundaries themselves have excellent corrosion resistance, and the triple junction containing twin boundaries breaks the connectivity of the original high angle grain boundary network, suppressing the corrosion of the grain boundaries.
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Ding Chao, Xie Tenglong, Xu Shenghang, Huang Minghao, Zhang Zhaoyang, Yang Xin, Tang Huiping, Zhao Yang
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240596
Abstract:According to the varying load in different directions, the anisotropy control of porous materials can significantly enhance the load-bearing efficiency of materials, thus better addressing the need for lightweight designs. In this paper, a modified G-A model for srtut-based porous materials accounting for the geometric parameters was established by taking G7 and BCCZ types of TC4 porous materials as examples. This model could serve as a guide for the precise control of anisotropy for strut-based porous materials. By adjusting the geometric parameters of common unit cells, a range of anisotropic porous materials with similar configurations but distinct properties were created. The influence of cellular geometric parameters on the anisotropic mechanical properties and failure modes of these materials was investigated through both vertical and lateral compressive tests, which also validated the efficacy of our modified model. The research results indicated that the mechanical properties of strut-based porous materials were primarily determined by the aspect ratio and the inclination angle of their struts. By fine-tuning the inclination angle of these struts, the anisotropic mechanical properties of the porous materials can be effectively modulated. At identical density levels, it could result in a substantial increase in the vertical compressive strength of G7 and BCCZ types of TC4 porous materials by 105% and 45%, respectively, with only a minor reduction in lateral compressive strength of 16% and 13%, by increasing the inclination angle of the diagonal struts from 35° to 55°.
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ZHU Xing, JIANG He, DONG Jianxin, WAN Zhipeng
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240603
Abstract:In order to study the hot cracking sensitivity of high alloying refractory superalloy GH4975, the crack morphology and microstructure characteristics of the ingot of GH4975 were observed, and the causes of hot cracking were analyzed by means of solidification behavior and thermodynamic calculation. The results show that the crack spreads along grain boundaries and dendrites, and the equiaxed crystal region has a greater tendency to crack than the columnar crystal region. Shrinkage holes are easy to appear in the center of the ingot. The formation of continuous shrinkage holes leads to insufficient overlap between dendrites, which is easy to be pulled apart under the action of stress to form a crack source. At the same time, the segregation of Al, Ti and Nb elements between dendrites is serious, and complex precipitates, especially a large number of (γ+γ ") eutectic phases, promote the nucleation and propagation of cracks. JMatPro"s calculation shows that GH4975 alloy has a large shrinkage rate in the solid-liquid two-phase zone and a wide range of non-complementary temperature, which is easy to form a shrinkage hole and become a crack source. Meanwhile, the linear expansion coefficient of the alloy changes greatly in the non-complementary temperature range, and the crack is easy to expand.
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Wang Sheng, Zhang Yali, Liu Haoming, Liu Yuchang, Wang Haoxu, Ma Ying, Li Yuandong
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240609
Abstract:This paper investigates the effects of voltage, pulse frequency, duty cycle and processing time on the corrosion resistance of micro-arc oxidised TC4 titanium alloy coatings using polar analysis of variance (ANOVA), with a subsequent objective of exploring the significance relationship and the optimum combination of the factor levels of the electrical parameters. Concurrently, an investigation was conducted into the mechanisms through which electrical parameters influence the corrosion resistance of the film layer, with a particular focus on its morphology and physical composition. A regression equation is established to facilitate regulation of the corrosion resistance properties of micro-arc oxidized films through manipulation of electrical parameters. The findings indicate that the duty cycle exerts the most significant influence on the electrochemical corrosion resistance of the membrane layer, the next most influential factors are pulse frequency and voltage, processing time was observed to have a comparatively lesser effect. The duty cycle and pulse frequency influence both structure and performance characteristics of the film layer by altering arc ignition discharge duration as well as arc quenching cooling times. An increase in voltage, duty cycle, processing time, or a decrease in pulse frequency can result in an enhanced power output from the power supply, this leads to an increase in film thickness along with larger pore sizes within microporous structures while reducing densification. Additionally, it promotes more efficient generation of Al2TiO5 within the film layer, however, this ultimately results in diminished electrochemical corrosion resistance. The results of the correlation coefficient testing demonstrate a strong relationship between the dependent and independent variables within the established regression equation. This finding provides theoretical support for predicting methods aimed at regulating performance characteristics in titanium alloy micro-arc oxidation films.
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Xiao Lairong, Li Shaohao, Zhao Xiaojun, Wang Xinyue, Wang Zihao, Cai Zhenyang, Lu ekang, Liu Sainan, Li Qingkui
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240615
Abstract:The single factor + Box-Behnken response surface method was used to optimize the impurity removal process of ammonium tungstate solution evaporation crystallization method to prepare higher purity ammonium paratungstate (APT). Firstly, in order to reduce the total content of four impurities (Na, K, S, Mo elements) in APT, the preferred range of crystallization temperature, stirring speed and initial concentration of ammonium tungstate solution was preliminarily determined by single factor method. Secondly, the evaporation crystallization impurity removal process of APT was further optimized by Box-Behnken response surface method, and the mutual influence of three factors on the total amount of four impurities in APT was studied. The results show that the order of influence of three factors on the total amount of four impurities is : initial concentration of ammonium tungstate solution > evaporation temperature > stirring speed ; the optimum process conditions were as follows : evaporation temperature 94 °C, stirring speed 1.25 m/s, initial concentration of ammonium tungstate solution 73 g/L. Under the experimental conditions, the total content of the four impurities in the prepared APT was reduced to 39.351 ppm, and the relative error with the optimal prediction value of the response surface method model was only 4.110 %, and the purity of APT reached 4N. The generated APT crystal is a columnar cuboid morphology with a small amount of broken crystals. The layered structure is obvious, the particle size distribution is uniform, and the grain refinement is obvious.
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Lan Hang, Lu Kaiju, Tong Yonggang, Wang Jie, Qiao jinjin, Chen Yongxiong, Hu Zhenfeng, Liang Xiubing
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240617
Abstract:Due to their low density, good room-temperature plasticity, and excellent high-temperature toughness, refractory niobium alloys have been used in hot-end components in the aerospace field. However, niobium alloys prepared by traditional casting methods are difficult to process parts with complex geometries, and met problems like long processing period, expensive price and high buy-to-fly ratio. The rapid development of additive manufacturing technology in recent years not only reduces the production period and cost, but also obtains superior mechanical properties, which brings new opportunities for the further application of niobium alloys. To this end, this paper reviews the current state-of-art research on additively manufactured niobium alloys, focusing on the laser and electron-beam additive manufacturing of two generations of typical niobium alloys, namely C-103 and Nb521, in particular with regard to the modulation of their mechanical properties and microstructure. In addition, common types of niobium alloys and additive manufacturing methods are briefly introduced. Finally, the future direction of additively manufactured niobium alloys and the problems that still need to be solved are proposed. By reviewing the field of additively manufactured niobium alloys, this paper provides a reference for the further application of niobium alloys in the aerospace field for hot-end components of complex structures.
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Zhu Dezhi, Chen Haipeng, Cai Liangfu
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240636
Abstract:The binder jetting 3D printing (BJ3DP) process is currently a research hotspot. Generally, the powder bed printing process requires spherical powders, which limits the preparation and printing of some HEA powders with large melting point differences. This study mainly focuses on the BJ3DP printing-sintering behavior of non-spherical particles. The results showed that the near-spherical AlTiCrNiCu low-density HEA powder with BCC structure was prepared by mechanical alloying, with a particle size ranged from 6.72 to 67.52 μm and an average particle size of 21.17 μm, which met the requirements of the BJ3DP printing process. The results of the orthogonal experiment indicate that when the binder saturation is 60%, the layer thickness is 120 μm, and the powder feeding speed is 15 pps, the green density of BJ3DP printing is the highest (about 44.7%). After sintering at 1190℃ for 4 hours, the density of the green body reaches 91.6%. The AlTiCrNiCu low-density HEA has a multiphase structure, with the B2 phase as the matrix, including BCC, FCC, and a small amount of L21 phase. The AlTiCrNiCu low-density HEA has high compressive properties, with a yield strength and compressive strength of approximately 840 MPa and 960 MPa, respectively. The research results provide ideas and reference for the BJ3DP printing and sintering of non-spherical metal powders, further expanding the application scope of metal powder BJ3DP printing and forming.
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Qin Zhonghuan, Wu Aiping, Yin Hongliang, Li Baoyong, Liu Qi, Wu Yong
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240637
Abstract:In this paper, the non-uniform microstructure and high temperature coordinated deformation behavior of 2A97 / 5A06 dissimilar aluminum alloy friction stir welded plate were studied. The microstructure of each area of the welded joint was observed, and the high temperature mechanical properties of each area and the whole joint was studied. It was found that the grains in the weld nugget zone of 2A97 and 5A06 were fine. The grain size of each region on the 2A97 side was small and basically close, and the grain size of each region on the 5A06 side was slightly larger and the difference was obvious. Under the process parameter of 430 °C and 10-3 s-1, the high temperature properties of 2A97 and 5A06 base metals are better, and the elongations are 278.8 % and 118.6 %, respectively. The strength and elongation of the nugget zone of the joint are 18.4 MPa and 176.1 %, respectively, which are between 2A97 and 5A06. The strength is about 2 times that of the 2A97 base metal, and the elongation is about 1.5 times that of the 5A06 base metal. The overall performance shows an obvious superposition principle. The deformation resistance of each region is different. The vertical weld specimen fractured after concentrated deformation in the 2A97 thermo-mechanically affected zone. After correction, the flow stress was slightly higher than that of the base metal and the elongation was close to that of the base metal. The grain size and flow stress of each region after welding meet the creep equation. The smaller the grain size, the lower the flow stress.
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Guan Weimian, Liang Xinzeng, Liu Lingling, Zhao Liang, Jin Yinling, Xu Jiwen, Jia Dawei, Liu Jiabin
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240643
Abstract:Cathode arc ablation limits the maximum operating time of arc plasma applications. Developing cathodes with extended service life is essential for improving the operating capability of current facilities, such as arc heaters and plasma welding. Understanding cathodic arc ablation behaviors and failure mechanisms is key to developing high-performance cathodes. This article first analyses the intricate arc ablation process of metallic cathodes and introduces failure mechanisms of sputtering, oxidation, and inhomogeneous ablation resulting from cathode spots. Furthermore, it reviews the recent advancements in improving cathode ablation resistance, including grain refinement, low work function addition, and gradient functionalization. In the final section, the future development of metallic cathodes is prospectively discussed based on in-situ observation of cathode spots, the construction of multi-field cathodic arc ablation model, and the establishment of a comprehensive cathode developing regime encompassing design, manufacturing, and testing processes.
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Yang Yiyan, Yang Guangyu, Zhang Zhao Zhong, Wu Hao, Zhang Jun, Jie Wan Qi
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240648
Abstract:The microstructure and room temperature mechanical properties of K4750 superalloy prepared by gravity casting and centrifugal casting were investigated, which included the second phase distribution, grain size, element segregation, distribution of shrinkage defects, room temperature mechanical properties and fracture morphology. It was found that the as-cast K4750 superalloy had similar microstructures prepared by two casting methods, namely γ matrix phase, MC-type carbide within grains, fine and dispersed γ" phase, as well as MC-type and M23C6 type carbides at grain boundary. However, these precipitates size were found to be more refined in the centrifugal casting methods. The average grain size of as-cast K4750 superalloy also decreased from 4.52 mm in the gravity casting to 2.22 mm in the centrifugal casting. Meanwhile, the area fraction of shrinkage defects was reduced from 1.75% in the gravity casting to 0.27% in the centrifugal casting. The dendrites of the gravity casting superalloy arranged neatly, whereas the dendrites of centrifugal casting superalloy were broken, and the segregation of elements was reduced. The K4750 superalloy samples prepared by centrifugal casting exhibited excellent room temperature mechanical properties, with yield strength, ultimate tensile strength and elongation of 632 MPa, 938 MPa and 11.2%, respectively. Compared with the K4750 superalloy prepared by gravity casting, its ultimate tensile strength increased by 20.6%, which may attributed to the combination of grain refinement, γ" phase refinement and casting defects reduction.
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Chen Zhebin, Cui Yue, Hu Lijuan, Ma Runze, Xu Shitong, Yao Meiyi
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240651
Abstract:Zirconium and its alloys have recently received considerable attention as candidate materials for dental implants due to its low modulus of elasticity, good corrosion resistance, and excellent biocompatibility. In this work, Zr-30Ti-xCu (x=0, 3, 7, mass fraction, %) alloys were designed by the valence electron concentration (VEC) theory. The microstructures of the alloys were characterized using SEM/EDS and TEM/EDS. The mechanical properties, corrosion behaviors, biocompatibility and antibacterial activities of the alloys were characterized through microhardness testing, room temperature tensile testing, electrochemical testing, contact angle testing, and antibacterial performance experiments. Results showed that after quenching at 650 ℃/15 min, the three alloy matrices were mainly composed of β phase. In the Cu-containing alloys, Zr2Cu second phase precipitated and the number of Zr2Cu particles increased with the increase of Cu content. With the increase of Cu content, the Vickers microhardness increased by 37 %, the contact angle decreased from 98.49° to 74.21° to improve the surface wettability. Meanwhile, it showed a significant inhibitory effect on Escherichia coli and Staphylococcus aureus, and enhanced the corrosion resistance of the alloy in physiological saline solution. The three alloys had low elastic modulus (67.8-78.9 GPa) and cytotoxicity, but their relationship with Cu content was not obvious. It can be seen that Zr-30Ti-xCu alloy exhibits excellent comprehensive properties, which can provide theoretical basis and guidance for the selection of new dental metal implants.
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Li Wenyu, Yang Weiming, Ma Yan, Liu Lichen, Zhang Xiang, Zhang Ping, Zhao Yuchen, Liu Haishun, 1
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240652
Abstract:In order to improve the surface wear resistance of metal parts, this study quantitatively analyzed the effect of ceramic particle content on the microstructure evolution and mechanical properties enhancement mechanism of high-entropy alloy gradient coating, and prepared dense and uniform high-entropy alloy gradient composite coating with different WC content on 45# steel substrate by laser cladding technology. The results show that with the increase of WC content, the grain size of the coating decreases from 20.16μm to 7.71μm, and the grain shape changes from cellular to dendrite and equiaxed. In addition, the microhardness of the gradient composite coating is significantly increased, which is 3 times that of the substrate, and 1.4 times higher than that of the high-entropy coating without adding WC. The coating mainly consists of body-centered cubic phase and metal carbide, and the corresponding diffraction peak intensity increases gradually with the increase of WC content. The wear performance test results show that the coating exhibits the best wear resistance when the WC content is 20 %, and the friction coefficient and wear amount are 0.4680 and 0.16 mg, respectively, which are lower than the WC40 coating with the highest average hardness, indicating that maintaining appropriate toughness while improving the hardness of the coating is the key to achieve the optimization of the coating performance. This study provides a certain reference value for the study of the optimization of high entropy alloy coatings prepared by laser cladding.
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XingBo, HaoZiyan, WangPengfei, ZhangShengnan, LiangMing, LiChengshan, LiJianfeng, ZhangPingxiang
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240661
Abstract:Cu-Ta composite with high strength, high electrical and thermal conductivity along with excellent thermal stability, is a promising candidate for applications in many fields, such as electrical devices, defense, rail transport, ultra-high field pulsed magnets and biomedical engineering. Extensive studies have been carried out to meet the application requirements, and significant results were achieved. This work provides a comprehensive review of recent developments in the fabrication methods, performance, and applications of Cu-Ta composites. Besides, the problems of present researches have been pointed out and development trends in future are prospected.
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Chen Zubin, Wang Xuhong, Tang Huaguo, Pan Kunming, Zhu Lilong
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240669
Abstract:Due to the excellent mechanical properties and excellent biocompatibility, TC4 titanium alloy has been widely used in the aerospace and medical devices field. Laser additive manufacturing (LAM) is an important means of forming and manufacturing titanium alloys. Large numbers of columnar crystals and acicular martensite existed in additive manufacturing TC4 titanium alloy should be addressed, which lead to anisotropy and plasticity reduction of material properties. In this work, molybdenum (Mo) was selected to regulate the microstructure and improve the properties of additive manufacturing TC4 titanium alloy, and the effect of Mo content on the microstructure and properties of laser additive manufacturing TC4 titanium alloy was explored. With the addition of Mo element, TiAl3 phase is gradually precipitated from the alloy matrix, and its content increases with the increase of Mo content. When the Mo content reaches 8wt.%, fine and dispersed lamellar structure is distributed in the alloy, and the β phase content increases sharply, and both the maximum grain refinement degree and dislocation density obtained. With the Mo content increasing from 0 to 10wt.%, the tensile strength, hardness and corrosion resistance of the alloy increase first and then decrease while the elongation follows the opposite trend, the Young"s modulus decreases gradually. When Mo content is 8wt.%, the alloy obtains the best mechanical strength and plasticity, the tensile strength, elongation and Young"s modulus are 1065.6MPa, 11.5% and 55.4GPa, respectively, and the corrosion resistance of the alloy is improved. Overall, TC4-8Mo sample has excellent mechanical properties and good corrosion resistance, and has the potential to be used as human medical implant materials.
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Xianghong Liu, Tao Wang, Xiaolong Ren, Jie Fu, Bin Zhu, Liang Cheng, Kaixuan Wang
Available online:April 10, 2025 DOI: 10.12442/j.issn.1002-185X.20240804
Abstract:A systematical analysis of the macro/microstructure, composition, and crystal orientation of the bright band were conducted using OM, SEM and EBSD methods, as well as Gleeble tests, to study the formation mechanism of bright band in forged TC18 alloy. The results show that: the bright bands in the center of TC18 alloy forgings correspond to β cube-grains in size of around 100mm; During the forging process, an inhomogeneous distribution of temperature and equivalent strain in the forging stocks is caused by adiabatic heating, which is an important reason for the microstructural heterogeneity; The large β cube-grains are formed due to the repeated compression along the orthogonal direction, which results in continuous strengthening of the <100> texture in the center of the forging stocks, and the merging of <100> grains with similar orientations; Through annealing treatment and compression along diagonal direction, it is possible to effectively reduce and avoid bright band defects in TC18 alloy.
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Yaguan Li, Zhenguo Nie, Huilin Li, Tao Wang, Qingxue Huang
Available online:April 08, 2025 DOI: 10.12442/j.issn.1002-185X.20250065
Abstract:The main parameters that characterize the morphology quality of multi-layer and multi-pass laser metal printed parts are the surface roughness and the error between the actual printing height and the theoretical model height. This study employed the Taguchi method to establish the correlation between process parameter combinations and multi-objective characterization of metal print morphology quality (height error and roughness). The signal-to-noise ratio (SNR) and grey correlation analysis method were used to predict the optimal parameter combination for multi-layer and multi-pass printing: laser power 800 W, powder feeding rate 0.3 r/min, step distance 1.6 mm, scanning speed 20 mm/s. Subsequently, we constructed the Genetic Bayesian-back propagation network (GB-BP) to predict multi-objective responses. Compared with the traditional BP network, the GB-BP network improved the accuracy of predicting height error and surface roughness by 43.14% and 71.43%, respectively. The network can accurately predict the multi-objective characterization of the morphology and quality of multi-layer and multi-pass LDED metal printed parts.
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