2026,Volume 55, Issue 2

>2026 Additive Manufacturing

• Regulation of Microstructure, Mechanical Properties, and Corrosion Properties of Laser-Melting-Deposited B₄C/TC4 Composite by Heat Treatment

  Zhao Cenya, Zheng Yang, Xiong Ruize, Ji Wenkang, Zhang Daohong, Liu Wei, Tao Hailin

  2026,55(2):285-291 DOI: 10.12442/j.issn.1002-185X.20250051

  Abstract(13) HTML(46) PDF(3.66 M)( 92)

  Abstract:The TiB+TiC dual-reinforced B₄C/TC4 composite was in-situ fabricated via incorporating 0.5wt% B₄C reinforcement during the laser melting deposition process. Different heat treatments of annealing and solid solution were used to regulate the microstructure, mechanical properties, and corrosion properties of B₄C/TC4 composite. Results show that with the increase in temperature from 500 °C to 800 °C, partial lamellar α-Ti in the as-deposited sample is gradually transformed into equiaxed α-Ti, accompanied by the disappearance of basketweave microstructure. At 1100 °C, a small portion of TiC phase suffers fusion. This composite exhibits the optimal combination of strength and plasticity after annealing at 500 °C for 4 h followed by furnace cooling, which is attributed to the stress release effect and the refined basketweave microstructure. However, this composite shows a decline in corrosion resistance after various heat treatments due to grain coarsening and micro-galvanic corrosion.

• Effect of Cyclic Heat Treatment on Fatigue Crack Growth Rate of Ti-6Al-4V-1Mo Alloy Prepared by Laser Directed Energy Deposition

  Xue Lipan, Zhang Fengying, Deng Yulin, Ye Zimeng, Zhao Kexin, Yu Zerong, Wu Wenlu, Su Wei, Yang Renjie

  2026,55(2):292-301 DOI: 10.12442/j.issn.1002-185X.20250307

  Abstract(9) HTML(28) PDF(3.00 M)( 71)

  Abstract:The fatigue crack growth rate of a novel Ti-6Al-4V-1Mo titanium alloy, which is developed for laser directed energy deposition technique, was investigated before and after cyclic heat treatment (CHT). Changes in microstructure, fracture surfaces, and crack growth paths were analyzed before and after CHT. Results indicate that in the stable crack growth region, the growth rates for the as-deposited and cyclic heat-treated specimens follow the relationships da/dN=1.8651×10^-8(ΔK)^3.2271 and da/dN=1.4112×10^-8(ΔK)^3.1125, respectively. Compared with that at the as-deposited state, the microstructure after CHT is transformed from a uniform basket-weave microstructure to a dual-phase microstructure consisting of near-spherical α and β-transformed matrix phases. The cyclic process also disrupts the continuity of the grain boundary α (α_GB) at the primary β-phase grain boundary. The coarsening of primary α and the disruption of α_GB continuity are the primary factors to release stress concentration and promote crack deflection, thereby decreasing the fatigue crack growth rate. Additionally, the increased occurrence of crack branching, secondary cracking, and crack bridging in cyclic heat-treated specimens further reduces the crack driving force and slows the fatigue crack growth rate.

• Research Progress on Process Optimization and Perfor-mance Control of Additive Manufacturing for Refractory Metals

  Lu Durui, Song Suocheng, Lu Bingheng

  2026,55(2):345-364 DOI: 10.12442/j.issn.1002-185X.20250370

  Abstract(57) HTML(31) PDF(11.22 M)( 75)

  Abstract:Refractory metals, including tungsten (W), tantalum (Ta), molybdenum (Mo), and niobium (Nb), play a vital role in industries, such as nuclear energy and aerospace, owing to their exceptional melting temperatures, thermal durability, and corrosion resistance. These metals have body-centered cubic crystal structure, characterized by limited slip systems and impeded dislocation motion, resulting in significant low-temperature brittleness, which poses challenges for the conventional processing. Additive manufacturing technique provides an innovative approach, enabling the production of intricate parts without molds, which significantly improves the efficiency of material usage. This review provides a comprehensive overview of the advancements in additive manufacturing techniques for the production of refractory metals, such as W, Ta, Mo, and Nb, particularly the laser powder bed fusion. In this review, the influence mechanisms of key process parameters (laser power, scan strategy, and powder characteristics) on the evolution of material microstructure, the formation of metallurgical defects, and mechanical properties were discussed. Generally, optimizing powder characteristics, such as sphericity, implementing substrate preheating, and formulating alloying strategies can significantly improve the densification and crack resistance of manufactured parts. Meanwhile, strictly controlling the oxygen impurity content and optimizing the energy density input are also the key factors to achieve the simultaneous improvement in strength and ductility of refractory metals. Although additive manufacturing technique provides an innovative solution for processing refractory metals, critical issues, such as residual stress control, microstructure and performance anisotropy, and process stability, still need to be addressed. This review not only provides a theoretical basis for the additive manufacturing of high-performance refractory metals, but also proposes forward-looking directions for their industrial application.

• SLM-3D Printed Soft Magnetic Alloys: Process, Performance, and Prospects

  Liu Bingxu, You Caiyin, Wang Fenghui, Tian Na, Liu Heguang, Zhang Jing, Zhu Xiaopei

  2026,55(2):365-388 DOI: 10.12442/j.issn.1002-185X.20250078

  Abstract(10) HTML(17) PDF(6.64 M)( 72)

  Abstract:Soft magnetic alloys are extensively used in various power electronic devices due to their advantageous properties, including high saturation magnetic induction, low coercivity, and high permeability. In certain applications, complex-shaped components are increasingly required for performance enhancement. Additive manufacturing technique, particularly selective laser melting (SLM), has emerged as an effective method for fabricating such complex-shaped soft magnetic components. SLM, a laser-based additive manufacturing technique, employs high-power-density lasers to melt and fuse metal powders within a powder bed selectively. This approach enables rapid prototyping, precise geometrical control, and the integration of multi-material designs. This review highlights recent advancements in the application of SLM technique for the production of soft magnetic alloys, focusing on Fe-Si, Fe-Ni, Fe-Co, and amorphous alloy systems. Moreover, it explores the implementation of SLM in manufacturing processes and evaluates both the opportunities and challenges associated with SLM-based production of soft magnetic alloys.

• Microstructure and Property Optimization Mechanisms of TiC/Al-Cu Alloys Prepared by Ultrasonic Frequency Pulsed Wire Arc Additive Manufacturing

  Jiang Zihao, Zeng Caiyou, Cai Xinyi, Zhao Yuan, Yang Qingfu, Cong Baoqiang

  2026,55(2):389-396 DOI: 10.12442/j.issn.1002-185X.20250332

  Abstract(19) HTML(24) PDF(2.55 M)( 76)

  Abstract:To address the issues of TiC particle agglomeration and pore defects of TiC particle-reinforced Al-Cu alloys prepared by wire arc additive manufacturing (WAAM), this study proposed a novel ultrasonic-frequency pulse (UFP)-assisted WAAM process. By modulating arc thermal characteristics, this method enhanced convective and turbulent behaviors in the melt pool, transitioning from a conventional Marangoni-driven flow to a more uniform dual-vortex structure. A computational fluid dynamics model was developed to trace TiC particle motion and revealed their improved mixing mechanism with the matrix under UFP conditions. Simulation results were validated by real-time melt pool imaging. Results showed that compared to conventional VPTIG, the UFP-VPTIG technique can significantly refine grains and improve homogeneity. Dispersed TiC particles are more uniformly, and porosity and segregation defects are reduced. This study offers a promising route for manufacturing high-performance Al-Cu alloy components.

• Mechanism of Pure Copper Binder Jetting Additive Forming and Sintering Densification

  Lv Shaobo, Yang Yongqiang, Wang Di, Liu Linqing, Wu Shibiao, Zhang Shiqin, Jiang Fei

  2026,55(2):397-405 DOI: 10.12442/j.issn.1002-185X.20240835

  Abstract(13) HTML(20) PDF(3.98 M)( 71)

  Abstract:The printing process and the debinding sintering process were carried out step by step to realize the pure copper processing with high laser reflectivity and high thermal conductivity. The process parameters of pure copper binder jetting additive manufacturing were studied. The effects of powder layer thickness and inkjet density on green parts forming performance were studied. At the same time, the effects of sintering atmosphere and sintering temperature on the densification process of the parts were studied. The results show that the combination of powder layer thickness of 75 μm and inkjet density of 50% can ensure the density and compression strength of green parts, resulting in high dimension precision and high surface quality. The driving force in hydrogen atmosphere is stronger than that in vacuum, and the surface oxide layer can be effectively reduced by the introduction of hydrogen. The compactness of sample treated at 1060 ℃ is 77.70%, the carbon residue forms pores to restrain the sintering process, and the compactness of sample treated at 1070 ℃ is 93.94%. It points out the direction for further optimizing the manufacturing process of binder jetting with pure copper.

• Mechanical and Thermal Properties of AlMgScZr Alloy with Primitive Lattice Structure of Different Volume Fractions

  Li Yi, Wang Xiaoqiang, Yi Wenjue, Zhou Yan, Wen Shifeng, Shi Yusheng

  2026,55(2):406-418 DOI: 10.12442/j.issn.1002-185X.20250262

  Abstract(9) HTML(14) PDF(3.84 M)( 76)

  Abstract:With the urgent demand for high-performance thermal management components in aerospace field, multifunctional components that combine efficient heat dissipation with excellent mechanical load-bearing capacity have become a focus of research. Using finite element simulation and experimental characterization methods, this study systematically investigated the influence of volume fraction on the forming quality, mechanical response, and heat exchange performance of AlMgScZr alloy Primitive lattice structures formed by selective laser melting (SLM) technique. The results indicate that although the SLM-formed Primitive structure exhibits surface roughness and dimensional deviations, its overall forming quality meets functional requirements. In terms of mechanical properties, an increase in volume fraction significantly enhances the mechanical performance of the lattice structure. When the volume fraction reaches 25%, the compressive modulus reaches 1664.06 MPa, the peak plateau stress is 42.85 MPa, and the energy absorption per unit volume increases significantly with increasing volume fraction. In terms of heat exchange performance, the Nusselt number (Nu) of the Primitive lattice structure with a volume fraction of 25% increases by 41.6% compared to that with a volume fraction of 10%. The increase in Reynolds number (Re) further enhances convective heat transfer efficiency, but this is accompanied by an increase in friction factor (f). This study achieved synergistic regulation of heat exchange and mechanical properties through volume fraction optimization, providing a reference for the application of Primitive lattice structures in thermal management components.

• Process Optimization, Microstructure and Properties of the GH4099 Fabricated by Binder Jetting 3D Printing

  Cheng Taoqian, Chen Ling, Su Zhaojiang, Li Baoyong, Chen Weiping, Fu Zhiqiang

  2026,55(2):419-428 DOI: 10.12442/j.issn.1002-185X.20250388

  Abstract(14) HTML(12) PDF(2.42 M)( 69)

  Abstract:This work investigated the forming process optimization, microstructure and properties of the GH4099 alloy fabricated by binder jetting 3D printing (BJ3DP) to meet the needs of forming accuracy and service performance of complex components. The effects of layer thickness, binder saturation, roller traverse speed and drying time on the surface quality of green samples were analyzed through orthogonal experiments. The results reveal that binder saturation is the main control factor. The optimized parameters significantly improve the forming uniformity and dimensional stability. In addition, the influence of sintering temperature on microstructure and properties was also investigated. It is found that when the sintering temperature is 1345 ℃, the relative density of the sample reaches 98.4%, and a large amount of coherent L1₂-Ni₃(Al,Ti) phase are precipitated in this sample. Under this condition, the optimum mechanical properties are obtained, i. e., tensile strength of 669 MPa and yield strength of 590 MPa. The work establishes the mechanism of the synergistic regulation of GH4099 microstructure-property by printing and sintering parameters of BJ3DP, providing new ideas and theoretical support for achieving high-performance complex components of nickel-based alloys.

• Effect of Heat Treatment on Microstructure and Mechanical Properties of Laser Powder Bed Fused ZrO₂-GNPs/2024Al Composites

  Mao Feng, Yao Sen, Hu Ruiting, Zhang Yanze, Yu Haocheng, Chen Yuhui, Chen Zhen

  2026,55(2):429-434 DOI: 10.12442/j.issn.1002-185X.20250170

  Abstract(9) HTML(15) PDF(1.96 M)( 78)

  Abstract:1wt%ZrO₂-0.2wt%GNPs/2024Al composites were prepared by laser powder bed fusion (LPBF) process. The phase composition and microstructure evolution of the as-deposited and heat-treated (475 ℃ solution treatment for 1 h+140 ℃ aging treatment for 12 h) composites were characterized to reveal the changes in mechanical properties. Results show that compared with that of the as-deposited samples, the microhardness of the composites is maximally enhanced under the heat treatment regime of 475 ℃/1 h+140 ℃/12 h. The second phases precipitated in the samples are mainly in the form of Al₂Cu strips and Al₂CuMg plates. The tensile strength and yield strength are increased from 382 MPa and 269 MPa to 624 MPa and 522 MPa, respectively, but the elongation is decreased from 16% to 5.6%. The strength enhancement is mainly attributed to the dislocation and load transfer strengthening effects caused by heat treatment, which has a much greater influence than the coarsening of the second phase and grain growth caused by heat treatment. The decrease in plasticity is mainly due to the coarse Al₂Cu and Al₂CuMg second phases which are prone to fracture and detach from the Al matrix, promoting to the premature formation of local shear bands and voids.

• Microstructure and Mechanical Properties of EA4T Steel Repaired by Laser Cladding IN625 Alloy

  Fang Xifeng, Wang Rui, Huo Huibin, Yang Qian, Sun Xiaoguang

  2026,55(2):435-442 DOI: 10.12442/j.issn.1002-185X.20240681

  Abstract(3) HTML(9) PDF(3.96 M)( 60)

  Abstract:IN625 superalloy was used to repair the surface of EA4T axle steel by laser cladding. The phase composition, microstructure, grain size and mechanical properties of different areas of IN625 laser cladding samples were analyzed by X-ray diffractometer, scanning electron microscope, Vickers hardness tester and universal experimental machine, respectively. The results show that the bottom of the IN625 laser cladding layer is the columnar crystal structure with multiple growth directions, the middle is the columnar crystal structure with single growth direction and the grain size is the largest, and the top is the mixed crystal region dominated by equiaxial crystal. The interdiffusion of Ni, Cr and Fe occurs between the cladding layer and the substrate, and the diffusion region is about 9 μm. The microhardness is 295 HV_0.2, the tensile strength is 888 MPa and the elongation is 38.0%.

• Precision Casting of Titanium Alloy Closed Impeller via Stereolithography 3D Printing

  Ji Zhijun, Ning Shuai, Li Shuai, Liu Yan, Ding Xianfei, Nan Hai, Huang Kuidong, Zhou Hongzhi, Lu Zhongliang, Li Dichen

  2026,55(2):443-450 DOI: 10.12442/j.issn.1002-185X.20250335

  Abstract(9) HTML(14) PDF(2.30 M)( 63)

  Abstract:To address the challenges of integrated shell molding in precision investment casting of titanium alloy closed impellers and the prolonged cycle time of conventional methods, a fabrication process for titanium alloy closed impellers based on stereolithography 3D printing has been developed. By optimizing powder bulk density by multilevel particle gradation and using ammonium citrate dispersants of 1.5wt% combined with alkaline environment of pH=10.0, a stable aqueous slurry with 62vol% solid content and 394 mPa·s viscosity was achieved, effectively suppressing Y₂O₃ hydration-induced slurry instability. The effect of key process parameters on molding performance was systematically investigated: the green body exhibits 18.9 MPa flexural strength at 62vol% solid content, which increases to 25.4 MPa after two vacuum impregnations with 20wt% nano-Y₂O₃ dispersion. Stereolithography 3D-printed resin prototypes combined with gel casting enable one-step fabrication of yttria molds with complex flow channels. Vacuum gravity casting successfully produces fully formed titanium alloy closed impellers, with no chemical sand adhesion observed after mold removal, and the microstructure characteristics and α layer thickness of the casting are essentially identical to those of ZTC4 casting produced by traditional investment casting process. Experimental results demonstrated that this process significantly shortens the lead time compared to traditional investment casting, providing a novel approach for cost-effective precision casting of high-performance titanium alloy components with complex geometries.

• Microstructure and Tribological Properties of Laser Cladding AlCoCrFeNi/WC High Entropy Alloy Gradient Composite Coatings

  Li Wenyu, Yang Weiming, Ma Yan, Liu Lichen, Zhang Xiang, Zhang Ping, Zhao Yuchen, Liu Haishun

  2026,55(2):451-459 DOI: 10.12442/j.issn.1002-185X.20240652

  Abstract(16) HTML(15) PDF(3.36 M)( 62)

  Abstract:Dense and uniform high-entropy alloy AlCoCrFeNi gradient composite coating with different WC content was prepared on 45# steel substrate by laser cladding technology. The effect of ceramic particle content on the microstructure evolution and mechanical properties enhancement mechanism of high-entropy alloy gradient coating was quantitatively analyzed in order to improve the surface wear resistance of metal parts. The results show that with the increase in WC content, the grain size of the coating decreases from 20.16 μm to 7.71 μm, 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 in WC content. The wear performance test results show that the coating exhibits the best wear resistance when the WC content is 20wt%, and the friction coefficient and wear amount are 0.4680 and 0.16 mg, respectively, which are lower than the coating with 40%wt WC which has 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.

• Research Progress on Refractory Metal Prepared by Powder Bed Fusion Additive Manufacturing

  Yang Guangyu, Wang Jian, Zhao Shaoyang, Yao Dengzhi, Xiao Bang

  2026,55(2):543-557 DOI: 10.12442/j.issn.1002-185X.20250327

  Abstract(15) HTML(16) PDF(1.76 M)( 75)

  Abstract:The development of additive manufacturing (AM) has brought innovative opportunities for the precision forming of high-melting-point refractory metals (such as tungsten, molybdenum, tantalum, niobium, and their alloys). However, due to the inherent properties of refractory metals such as high melting point, their AM processes exhibit significant particularities different from those of other metal materials. Based on the metal powder bed fusion (PBF) AM techniques represented by selective laser melting (SLM) and selective electron beam melting (SEBM), this paper systematically reviewed the research progress of tungsten, molybdenum, tantalum, niobium, and their alloys in AM field. The research focused on the powder preparation technique of refractory metals, as well as the microstructure regulation strategies of typical process defects (such as pore, cracking, grain coarsening) during the forming process and mechanical properties of these alloys. In addition, this paper also summarized the key faced in the industrialization process of refractory metals prepared by AM and prospected the future development trends.

>Materials Science

• Effect of Initial Microstructure States on Flow Behavior of Al-Zn-Mg-Cu Alloy During Hot Tensile Deformation

  Wang Shuyan, Zhou Yuting, Du Ruibo, Long Shuai, Lin Haitao, Wang Shaoyang

  2026,55(2):302-314 DOI: 10.12442/j.issn.1002-185X.20250100

  Abstract(11) HTML(21) PDF(6.51 M)( 74)

  Abstract:To investigate the influence of Al-Zn-Mg-Cu alloy with as-homogenized and as-rolled initial microstructures on the tensile flow behavior, isothermal tensile tests were conducted on a GLEEBLE-3500 isothermal simulator at temperatures of 380–440 °C and strain rates of 0.05–1 s^-1. The Johnson-Cook model, Hensel-Spittel model, strain-compensated Arrhenius model, and critical fracture strain model were established. Results show that through the evaluation of the models using the correlation coefficient (R) and the average absolute relative error, the strain-compensated Arrhenius model can represent the flow behavior of the alloy more accurately. Shear bands are more pronounced in the as-homogenized specimens, whereas dynamic recrystallization is predominantly observed in as-rolled specimens. Fracture morphology analysis reveals that a mixed fracture mechanism is prevalent in the as-homogenized specimen, whereas a ductile fracture mechanism is predominant in the as-rolled specimen. The processing maps indicate that the unstable region is reduced in the as-rolled specimens compared with that in the as-homogenized specimens. The optimal hot working windows for the as-homogenized and as-rolled specimens are determined as 410–440 °C/0.14–1 s^-1 and 380–400 °C/0.05–0.29 s^-1, respectively.

• Microstructure and Thermal Properties of MoSi₂ and Gd₂Zr₂O₇ Composite Coatings on Mo-Re Alloy

  Zhang Chong, Wang Xin, Xu Hailong, Li Yanchao, Ma Tongxiang, Wang Shaopeng

  2026,55(2):315-321 DOI: 10.12442/j.issn.1002-185X.20250091

  Abstract(13) HTML(16) PDF(2.62 M)( 60)

  Abstract:Dual-layer thermal barrier coatings (TBCs) with ultrahigh temperature resistance were prepared on the surface of molybdenum-rhenium alloy hot-end components. The preparation of the MoSi₂-Gd₂Zr₂O₇ dual-layer TBCs was designed based on the coefficient of thermal expansion and the coating functionality, and it was completed using atmospheric plasma spraying technique. The microstructure, mechanical properties, and thermal properties were analyzed. Results indicate that the adhesion of the prepared dual-layer composite TBCs is excellent, and no noticeable cracks appear at the interface. Compared with the MoSi₂ coating with a low fracture toughness (0.88 MPa·m^1/2), the Gd₂Zr₂O₇ coating exhibits higher fracture toughness (1.74 MPa·m^1/2) and stronger resistance to crack propagation. The prepared MoSi₂-Gd₂Zr₂O₇ composite coatings have a high porosity (39%), low thermal conductivity (1.020 W·(m·K)^-1, 1200 °C), and low thermal diffusivity (0.249 mm²/s, 1200 °C). Additionally, they possess a high oxygen-vacancy concentration, which ensures excellent insulation performance.

• Influence of Homogenization on Microstructure Character-istics of Yttrium-Modified GH3535 Alloy

  Wang Yumiao, Liang Wenjun, Li Xiaoli, Jiang Sheng, Zhou Xingtai, Qiu Hanxun

  2026,55(2):322-332 DOI: 10.12442/j.issn.1002-185X.20250038

  Abstract(11) HTML(17) PDF(4.23 M)( 73)

  Abstract:The influence of homogenization parameters on element segregation, dendritic structure, and the precipitate evolution in the GH3535-0.08wt% Y alloy was investigated. Additionally, some specific homogenization parameters were maintained constant throughout the experiments. Results indicate that the heat treatment at 1150 °C for 10 h is the optimal homogenization condition. Following this optimal treatment, dendrite structures and element segregation are eliminated. Furthermore, both SiC and Y₅Si₃ precipitates in the as-cast alloy decrease significantly. Conversely, the homogenization at 1188 °C induces overheating defects within the alloy. Although SiC and Y₅Si₃ phases also decrease, some large M₆C phases can still be observed, adversely affecting subsequent forging processes.

• Effect of Ta Element on Microstructure and Mechanical Properties of Nb-22Si-20Ti-6Mo Alloy

  Xu Qin, Ma Xiaohang, Wang Qi, Wang Jiantong, Chen Dezhi, Yin Yajun, Chen Ruirun

  2026,55(2):460-466 DOI: 10.12442/j.issn.1002-185X.20240685

  Abstract(9) HTML(10) PDF(1.78 M)( 56)

  Abstract:Nb-22Si-20Ti-6Mo-xTa (x=0, 1, 2, 3, 4, at%) alloys with different contents of Ta were prepared by vacuum non-consumable arc melting method, and effects of Ta content on phase constitution, microstructure and mechanical properties of Nb-22Si-20Ti-6Mo-xTa alloys were investigated. Results show that addition of Ta does not change the phase composition Nb-22Si-20Ti-6Mo-xTa alloys. All alloys consist of Nbss and β-Nb₅Si₃, and Ta is mainly dissolved in Nbss. Microstructure of alloys consists of bulk primary β-Nb₅Si₃ phase and Nbss/β-Nb₅Si₃ eutectic. Addition of Ta refines the microstructure, and the grain size of primary β-Nb₅Si₃ phase decreases from 26.84 μm to 14.65 μm. In addition, the amount of primary phase is decreased with increasing the Ta content, and the amount of eutectic structure is increased. Room-temperature compressive strength of Nb-22Si-20Ti-6Mo-xTa alloys is improved with increasing the Ta content, and it is increased from 2261 MPa to 2321 MPa with increasing the Ta content from 0at% to 4at%. Fracture strain of Nb-22Si-20Ti-6Mo-xTa alloys first decrease and then increase with increasing the Ta content. Fracture strain of NST-0Ta alloy is 9.9%, that of NST-1Ta alloy is 9.7%, and that of NST-4Ta alloy increases to a maximum of 10.6%. Compressive strength improvement of alloys is contributed to solid solution strengthening and grain refinement strengthening by the addition of Ta. Due to refinement of alloy microstructure and the increase in eutectic structure, fracture strain of alloy is increased.

• Microstructure and Properties of Dental Implant Zr-30Ti-xCu Alloys

  Chen Zhebin, Cui Yue, Hu Lijuan, Ma Runze, Xu Shitong, Yao Meiyi

  2026,55(2):467-478 DOI: 10.12442/j.issn.1002-185X.20240651

  Abstract(8) HTML(13) PDF(3.96 M)( 55)

  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, wt%) alloys were designed by the valence electron concentration theory. The microstructures of the alloys were characterized using SEM/EDS and TEM/EDS. The mechanical properties, corrosion behavior, 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 show that after quenching at 650 ℃/15 min, three alloy matrices are mainly composed of β phase. In the Cu-containing alloys, Zr₂Cu second phase precipitates and the number of Zr₂Cu particles increases with the increase in Cu content. With the increase in Cu content, the Vickers microhardness increases by 37%, and the contact angle decreases from 98.49° to 74.21°, indicating the surface wettability improvement which shows a significant inhibitory effect on Escherichia coli and Staphylococcus aureus. Besides, the corrosion resistance of the alloy in physiological saline solution is enhanced. Three alloys have low elastic modulus (67.8–78.9 GPa) and cytotoxicity, but their relationship with Cu content is 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.

• Deformation Behavior and Related Dynamic Recrystallization Mechanism of High Purity Copper During Hot Deformation

  Hao Huijun, Yang Anheng, Cheng Jun, Zhou Wenyan, Kang Feifei, Mao Yong, He Junjie

  2026,55(2):479-490 DOI: 10.12442/j.issn.1002-185X.20240678

  Abstract(13) HTML(11) PDF(5.84 M)( 57)

  Abstract:The microstructure of high-purity copper targets has a significant impact on the quality of sputtered films. This study investigated the evolution of the microstructure and dynamic recrystallization mechanism of copper targets from the perspective of hot working. The hot deformation behavior of high-purity copper at temperatures ranging from 500 ℃ to 650 ℃ and strain rates from 0.01 s^–1 to 10 s^–1 was studied through isothermal compression experiments. The results show that the evolution of the microstructure and the recrystallization mechanism are closely related to the Zener-Hollomon parameter Z. As the temperature increases and the strain rate decreases, the lnZ decreases, and the average grain size decreases, both the microstructure homogenization and dynamic recrystallization enhance, and the texture transitions from a strong deformation texture of Cube ND{001}<110> to Cube{001}<100> and Goss{011}<100>. The dynamic recrystallization mechanism changes at different lnZ values. Local recrystallization occurs at high lnZ values, which is a discontinuous dynamic recrystallization (DDRX) mode. At middle lnZ value, the degree of recrystallization increases, the orientation difference increases uniformly and the lattice rotates gradually. At low lnZ values, continuous dynamic recrystallization (CDRX) of progressive rotation of lattice and geometric dynamic recrystallization (GDRX) of grain "pinching" occur. At low lnZ value of 650 ℃, 10 s^–1, homogeneous fine microstructure and weak texture strength are obtained. The research can provide theoretical guidance for the optimization of hot working technology of high purity metal sputtering targets.

• Effects of Rolling Deformation and Solution Treatment on Microstructure and Texture of IMI834 Plate

  Yang Nan, Wang Ruiqin, Shi Lichao, Chen Zhiting, Yang Heng, Peng Chen, Zhang Shuang

  2026,55(2):491-500 DOI: 10.12442/j.issn.1002-185X.20240683

  Abstract(7) HTML(7) PDF(5.86 M)( 59)

  Abstract:IMI834, as a high-performance titanium alloy resistant to 600 ℃, faces limitations in its application due to issues such as a narrow processing window, weak deformation ability, and high deformation resistance. Although it is feasible to control the sheet's microstructure and texture by adjusting the rolling thickness and post-rolling heat treatment, related research remains insufficient. In this study, the effects of deformation and solution treatment temperature on the microstructure and texture of IMI834 sheets was investigated by scanning electron microscopy and back scattered electron diffraction techniques. The results indicate that as the rolling deformation increases, the sheet's microstructure gradually transforms into banded and equiaxed fine-grained structures, in which the banded structure exhibits an RD texture. Additionally, reversing the rolling direction can increase the proportion of equiaxed fine-grained structures. Appropriate solution treatment can effectively weaken the basal texture, thereby reducing the sheet's deformation anisotropy.

• Effect of Decreasing Homogenization Temperature on Microstructure and Properties of 2024-T3 Alloy

  Wang Yali, Cao Lingfei, Wen Qinghong, Jiang Yuan, Wu Xiaodong

  2026,55(2):501-509 DOI: 10.12442/j.issn.1002-185X.20240689

  Abstract(4) HTML(10) PDF(3.57 M)( 58)

  Abstract:The effect of decreasing the homogenization temperature on the microstructure and mechanical properties of 2024-T3 alloy was investigated. The results show that the area fractions of the residual coarse secondary phases of alloys after homogenization at 430 or 460 ℃ for 24 h followed by rolling are similar, and they are higher than those of the alloys homogenized at 490 ℃ for 24 h. The latter treatment is routinely used in the industry. The alloys with homogenization of 430 ℃/24 h or 460 ℃/24 h and solution treatment have higher recrystallization fractions and finer grain sizes due to the particle stimulated nucleation (PSN) effect of the coarse secondary phase. Hardness tests and tensile tests show that the peak hardness, tensile strength, yield strength, and elongation of the three alloys are relatively similar to each other. Therefore, appropriately decreasing the homogenization temperature can improve the uniformity of grain size, reduce the cost, and maintain the excellent tensile properties of 2024-T3 plates. Whereas the high-temperature homogenization of 490 ℃/24 h can make the 2024-T3 sheet have relatively good plasticity and toughness.

• Molecular Dynamics Simulation of the Effects of Void Defect on the Tensile Deformation Behavior of α-Fe

  Li Xiang, Yin Yihui, Zhang Yuanzhang, Li Jicheng, Li Hongxiang

  2026,55(2):510-516 DOI: 10.12442/j.issn.1002-185X.20240692

  Abstract(5) HTML(7) PDF(2.52 M)( 58)

  Abstract:To further investigate the effects of void defect on the plastic deformation behavior of α-Fe under tensile load, the molecular dynamic models of the α-Fe samples with the void defects were established and related simulations under uniaxial tension were carried out for a series of models. The results show that overall, the deterioration of tensile mechanical properties of the sample with void is positively related to the void size. The larger the void size, the easier the occurrence of plastic deformation stage for sample. Overall, the Young's modulus, yield stress, ultimate tensile strength and tensile elongation of the samples containing void decrease with increasing the radius of void. The plastic deformation mechanism is of a mixture of the tensile stress-induced structural phase transition and the dislocation slip. However, the characteristics of stress-strain curves change significantly with increasing the radius of void, the plastic yield stage and strain hardening stage of the sample become shorter, and the strain hardening stage even vanishes. The research deepens the understanding of the effects of void defect on the mechanical properties and plastic deformation mechanisms of metals and lays a useful foundation for the subsequent analysis and study of the physical and mechanical properties of polycrystalline α-Fe materials under various conditions.

• Effect of Forging Process and Heat Treatment on Microstructure and Mechanical Properties of Er7050 Aluminium Alloy

  Liu Yuhang, Rong Li, Huang Hui, Chen Jiongshen, Ma Chenxi, Shi Xiaocheng, Wei Wu, Wen Shengping, Gao Kunyuan, Wu Xiaolan, Nie Zuoren

  2026,55(2):517-527 DOI: 10.12442/j.issn.1002-185X.20240697

  Abstract(9) HTML(12) PDF(6.68 M)( 64)

  Abstract:In order to explore the effect of multi-directional forging on the microstructure and mechanical properties of aluminium alloy, this paper took the homogenized Er7050 aluminum alloy as the research object. The alloy samples were subjected to multi-directional forging of three kinds of forging passes at 400 ℃, namely three-time upsetting and three-time cross stretching (3U3CS), 6U6CS and 9U9CS. Subsequently, the samples were subjected to solid solution treatment, water quenching and T6 aging treatment. The microstructure and mechanical properties of the samples were analyzed. Comparison of the mechanical properties of the samples obtained by the different forging processes reveals that the sample treated by the 9U9CS forging process has the best mechanical properties, which is attributed to its fine grains and dense precipitated strengthening phases. The average tensile strength of the sample under this forging process is 621.4 MPa, the average yield strength is 545.4 MPa, and the average elongation is 13.58%, which indicates that the optimized forging process significantly improves the mechanical properties of the alloy.

• Finite Element Simulation and Experimental Analysis of Mg Alloy Processed by Inverse Temperature Field Equal Channel Angular Pressing

  Meng Shuaiju, Song Jinlong, Chen Jianfei, Zhang Jianjun, Wang Lidong, Qi Jianing, Li Yongfei, Yang Guirong

  2026,55(2):528-534 DOI: 10.12442/j.issn.1002-185X.20240699

  Abstract(5) HTML(7) PDF(1.46 M)( 55)

  Abstract:To investigate the influence of mold temperature on the temperature field and equivalent stress field of Mg alloy processed by inverse temperature field equal channel angular pressing (ITF-ECAP), a thermal mechanical coupled finite element analysis model was established for ITF-ECAP processing of B2 alloy (Mg-1.5Bi, wt%). Combined with experimental research, the processing process of B2 alloy at different mold temperatures was analyzed. The results show that during the ITF-ECAP, the temperature of the billet significantly increases at the corner of the mold channel, which facilitates smooth plastic deformation. After severe deformation, the temperature gradually decreases, thereby inhibiting coarsening of recrystallized grains. The stress concentration of the billet mainly occurs at the corner of the channel and near the mold outlet, and it significantly decreases with the increase in mold temperature. The experiment verification finds that when the mold temperature is low (200 ℃), the surface cracking of B2 alloy billet occurs after one-pass ITF-ECAP processing. In contrast, the surface of B2 alloy can be ITF-ECAP processed for four passes without surface cracking when the mold temperature is set as 300 ℃. Further microstructural characterization reveals that a bimodal grain structure composed of fine and ultrafine grains is formed after four-pass ITF-ECAP deformation, leading to a simultaneous improvement in both strength and ductility.

• Microstructure and Texture Evolution Mechanism of Ti-3Al-5Mo-4.5V Titanium Alloy Under the Synergistic Control of Rolling-Drawing-Annealing Cooling

  Sun Xiaoping, Liu Dong, Du Yuxuan, Lei Lei, Zhang Penghui, Wu Cong, Lei Fan

  2026,55(2):535-542 DOI: 10.12442/j.issn.1002-185X.20250277

  Abstract(6) HTML(15) PDF(14.15 M)( 61)

  Abstract:The synergistic evolution mechanism of microstructure and texture of Ti-3Al-5Mo-4.5V (TC16) alloy bar was revealed under rolling-drawing-different annealing cooling (water quenching (WQ), air cooling (AC) and furnace cooling (FC)). The results show that the initial lamellar structure of TC16 titanium alloy bar has a dual-phase structure composed of equiaxed α and β phases through dynamic recrystallization and α phase growth during two-phase rolling and annealing. The β phase and α phase form the axial silk texture of <110>//bar and //bar, respectively. Although hot drawing does not change the texture type, the hot drawing deformation leads to a significant increase in the internal grain orientation gradient, which in turn significantly weakens the texture intensity. The annealing cooling rate has a significant effect on the content of α phase, and the content of equiaxed α phase increases from 36.8vol% (WQ) to 74.9vol% (FC). The texture types of β phase and α phase at different cooling rates are consistent with the drawn texture. The α→β phase transition in the annealing heating stage retains and strengthens the original β phase texture through the Burgers orientation relationship. During the cooling process, the β→α phase transition triggers the selection of variants due to the adaptive effect, resulting in an increase in the texture strength of the α phase. It can be seen that heat treatment can retain and strengthen the rolling-drawing texture, rather than reconstruct its type. This study provides reference and guidance for the optimization of microstructure and texture of titanium alloy through the synergistic control strategy of hot processing and cooling.

>Reviews

• Research Status and Prospects of Platinum Group Metal Coatings with High-Temperature Oxidation Resistance

  Ding Chenxi, Liu Zhongyu, Fang Zhen, Wang Haoxu, Lv Biao, Hu Zhenfeng

  2026,55(2):333-344 DOI: 10.12442/j.issn.1002-185X.20240524

  Abstract(14) HTML(13) PDF(2.00 M)( 73)

  Abstract:Platinum group metals have high melting points, strong corrosion resistance, stable chemical properties, and low oxygen permeability in high-temperature oxygen-containing environments. As thermal protective coating materials, they have gained essential applications in the aerospace field and have excellent prospects for application in frontier military fields, such as protecting hot-end components of hypersonic aircraft. This research reviewed the latest research progress of platinum group metal coatings with high-temperature oxidation resistance, including coating preparation techniques, oxidation failure, and alloying modification. The leading preparation techniques of current platinum group metal coatings were discussed, as well as the advantages and disadvantages of various existing preparation techniques. Besides, the intrinsic properties, failure forms, and failure mechanisms of coatings of single platinum group metal in high-temperature oxygen-containing environments were analyzed. On this basis, the necessity, main methods, and main achievements of alloying modification of platinum group metals were summarized. Finally, the future development of platinum group coatings with high-temperature oxidation resistance was discussed and prospected.

• A Review： Status Quo and Prospect on Welding Techniques of Zr Alloys

  Bai Yujie, Li Yuanxing, Zhu Zongtao, Chen Hui

  2026,55(2):558-572 DOI: 10.12442/j.issn.1002-185X.20240724

  Abstract(14) HTML(18) PDF(3.19 M)( 75)

  Abstract:In recent years, clean nuclear energy has developed rapidly. Zr alloys are commonly used as fuel element cladding materials in water-cooled nuclear reactions due to their good corrosion resistance and low neutron absorption cross-section. The nuclear fuel is usually sealed in a Zr alloy envelope by welding, so its weld quality is particularly critical. The high heat input of traditional fusion welding leads to large deformation, and the porosity and intermetallic compounds (IMCs) in the brazing process tend to damage the joint performance, and low-temperature diffusion bonding of Zr alloys can avoid the above problems. Therefore, this paper analyzed the weldability of Zr and its alloys, reviewed the research status of their welding technologies including fusion welding, brazing, and diffusion bonding, briefly introduced two kinds of pre-welding optimization methods, namely surface mechanical attrition treatment (SMAT) and thermo-hydrogen processing (THP). Finally, it summarized and prospected the applications in low-temperature diffusion bonding of Zr alloys.

Online First

• Low-Temperature Impact Toughness and Fracture Mechanisms of a High-Strength, High-Toughness TC4-0.55Fe Titanium Alloy

  Wang Delong, He Miaoxia, Gao Wenshuo, Guo Yumeng, Dong Yuecheng, Igor V. Alexandrov

  Available online:January 12, 2026  DOI: 10.12442/j.issn.1002-185X.20250391

  Abstract(77) PDF(2.32 M)(5)

  Abstract:Because of their exceptional corrosion resistance and superior low-temperature mechanical properties, titanium alloys are ideal structural materials for critical equipment operating under extreme conditions, such as Arctic resource exploitation and polar shipping routes. To further enhance low-temperature toughness and clarify the fracture–failure mechanisms of titanium alloys, a TC4-0.55Fe alloy was produced by micro-alloying with Fe, and its impact performance and fracture behavior were systematically investigated over the temperature range 20?°C toS?196?°C. The alloy exhibits a room-temperature Charpy impact toughness of 66.75?J?cm?2, which remains unchanged down to ?20?°C. When the temperature is lowered to ?70?°C, the toughness decreases to 46.75?J?cm?2, and at ?196?°C it still retains 25.1?J?cm?2—representing a 23.8?% improvement over conventional TC4. Scanning electron fractography confirms that ?196?°C is still above the alloy’s ductile–brittle transition temperature. EBSD characterization reveals abundant deformation twinning in the vicinity of the crack at all test temperatures, with twin density increasing markedly as temperature decreases. The outstanding impact toughness of the TC4-0.55Fe alloy is attributed to the synergistic effects of grain refinement, the dispersion of fine acicular α_s precipitates within the β matrix, and the pronounced rise in twin density at low temperature; together they promote crack-path deflection and significantly enhance resistance to fracture.

• Effect of Mo Element on the Microstructure and Properties of Laser Powder Bed Fusion Co-Cr-Fe Alloy

  He Yazhou, Hou Yaqing, 米志杉, Wang Ziyu, Lu Yongchao, Li Xiaoqun, Zhou Dong, Su Hang

  Available online:December 24, 2025  DOI: 10.12442/j.issn.1002-185X.20250492

  Abstract(35) PDF(1.89 M)(36)

  Abstract:Compositionally graded 15Co-25Cr-(60-x)Fe-xMo (x=0-5, wt.%) specimens were fabricated via laser powder bed fusion (LPBF) using blended elemental powders of Co, Cr, Fe, and Mo, employing an in-situ alloying strategy. The compositional homogeneity, phase constitution, and microstructure of the specimens with varying Mo content were systematically investigated. Furthermore, the influence of Mo content on the magnetic properties was elucidated by integrating experimental findings with first-principles calculations. The results indicate that all specimens achieved full alloying without defects such as porosity or un-melted particles. The magnetic properties exhibit a non-monotonic trend with increasing Mo content, initially enhancing before deteriorating. Optimal magnetic performance is obtained at 3 wt.% Mo, yielding a coercivity (H_c) of 26.54 kA/m, a remanence (B_r) of 0.9 T, and a maximum energy product (〖(BH)〗_max) of 11.56 kJ/m3.Additionally, Mo incorporation was found to enhance the microhardness of the alloys, with the 15Co25Cr57Fe3Mo sample exhibiting a hardness of 424 HV0.5.

• Study on Synergistic Optimization of Microstructure and Mechanical Properties of Zr-based Eutectic Alloy

  Chen Lihe, Wang Rui, Yao Xinwei, Hai Nuo, Gao Yinghong, Zhang Zhouran, Li Shun

  Available online:December 17, 2025  DOI: 10.12442/j.issn.1002-185X.20250283

  Abstract(45) PDF(1.66 M)(37)

  Abstract:This investigation adopts a strategic approach focusing on low-melting point eutectic alloy design supplemented by thermodynamic calculations of phase diagrams to develop and characterize Zrx(NiFe)100-x alloy systems (x=75/83/90 wt.%). Results demonstrate that at Zr concentrations of 83 wt.% and above, the alloys develop a distinctive lamellar eutectic microstructure (tI12-Zr2(Ni/Fe)/FCC-Zr) coexisting with HCP-Zr, featuring nanoscale FeZr3 interphase precipitates at eutectic interfaces. Notably, the liquidus formation temperature exhibits a substantial reduction to approximately 974℃, successfully achieving the desired low-melting point characteristics. The Zr83(NiFe)17 and Zr90(NiFe)10 alloys exhibit compressive strengths of 1352±12 MPa and 1253±10 MPa with corresponding fracture strains of 14.2±0.4% and 17±0.3%, respectively. These values represent a significant enhancement in fracture strain compared to conventional Zr-based amorphous alloys while maintaining comparable strength properties. Fractographic analysis reveals that dislocation pinning mechanisms and shear band bifurcation phenomena induced by eutectic interfaces effectively impede crack propagation, facilitating a transition in fracture mode from brittle cleavage to 45° shear-dominated failure with increasing Zr content. Under dynamic compression, both 83Zr and 90Zr alloys exhibit a strain rate hardening effect, and when the strain rate exceeds a critical value, the alloys undergo a ductile-to-brittle transition. This research establishes a fundamental framework for the design of low-melting point Zr-based eutectic multiphase alloys.

• Effects of Microstructure Characteristics on Impact toughness of GH4151 alloy

  TangChao, Liu Jie, Luo Junpeng, Zhang Maicang, Xie Xingfei, Qu Jinglong, Zhang Ji

  Available online:December 17, 2025  DOI: 10.12442/j.issn.1002-185X.20250461

  Abstract(26) PDF(2.28 M)(35)

  Abstract:Seiries oscilloscope impact tests were conducted for GH4151 alloy under different heat treatment parameters, then microstructure characteristics and grain boundary properties were investigated by using phase diegram calculation, precipitates and EBSD analysis by SEM and detailed phase structure determined by TEM, the relationship between microstructure evolution and impact toughness of GH4151 alloy was systematically studied. The results show that the percentage of primary γ′ phase gets lower with the inceasing of annealing solution temperature, while the average grain size gets greater. The JMat Pro results depict that for GH4151 alloy there exists a certain amount of μ phase, a type of TCP phase, at the grain boundary, besides the secondary carbides of M23C6. Oscilloscope impact tests show that the crack initiation energy including elastic deformation enegy and plastic deformation energy and the propagation enegy for annealing solutioned specimens were all greater than that of annealing aged ones, resulting the good resistance of crack initiation and propagation and good property of inpact toughness. and the impact toughness gets lower when the specimens were annealing aged due to the smaller crack initiation energy and propagation enegy. Further microstructure analysis by TEM shows that the tested impact toughness values were increased with the increase of average grain size and had little relationship with the properties of grain boundary. The main reasons that the sharp decrease of impact toughness for annealing aged specimens were the finer grain size and M23C6 carbides and μ phase precipitate at the grain boundary.

• Study on High-Temperature Oxidation Behavior and Mechanisms of 3rd-Generation TiAl Alloys

  Ji Xiankun, Dang Yuyang, Leng Kun, Wang Ying, Xia Zhizhou, Liu Shaohua, Zhao Chunling, Cui Yuyou, Zhang Chao

  Available online:December 12, 2025  DOI: 10.12442/j.issn.1002-185X.20250465

  Abstract(26) PDF(1.98 M)(33)

  Abstract:The high-temperature environmental adaptability of TiAl alloys is crucial for the service safety of aero-engine low-pressure turbine blades. This study investigates the cyclic oxidation behavior of a cast ZTNM TiAl alloy at 650℃ and 750℃ in accordance with the HB5258 standard. The results indicate that the oxidation weight gain kinetics of the alloy at both temperatures follow a parabolic law. The oxidation rate at 650℃ (k′ = 0.0082 gm^-2h^-1) is lower than that at 750℃ (k′ = 0.0095 gm^-2h^-1), with both rates qualifying as "complete anti-oxidation" grade. The oxidation process comprises three distinct stages: the initial formation of a mixed TiO2 and Al2O3 scale; followed by the development of a continuous TiN/Ti2AlN nitride layer at the scale / metal substrate interface during the intermediate stage; and finally, the formation of an Al-depleted zone within the oxide scale after long-term exposure. The higher temperature (750℃) promotes the growth of TiO2, resulting in a thicker oxide scale. The nitride layer plays a critical role in determining the oxidation rate and the structural stability of the scale.

• Precipitation Behavior During Long-Term Aging of Ni-Cr-W-Mo Alloy and Its Effect on Mechanical Properties

  Gao Shuai, He Xikou, Jia Lei, Tang Zhengxin, Bao Hansheng, Yin Xue, Dong Wenjun, Liu Zhengdong

  Available online:December 09, 2025  DOI: 10.12442/j.issn.1002-185X.20250448

  Abstract(25) PDF(1.58 M)(34)

  Abstract:Using techniques such as SEM, TEM, and phase analysis, the precipitation behavior during long-term aging at 800°C and its effect on the mechanical properties of a Ni-Cr-W-Mo alloy were investigated. The results indicate that during aging, M23C6 carbides precipitated sequentially at grain boundaries, twin boundaries, and within grains in different morphologies. The intergranular lamellar M23C6 was a product of a discontinuous reaction, while the granular M23C6 at twin boundaries grew along the {111} twin planes. The intragranular nanoscale M23C6 contributed to pinning strengthening. M6C carbides underwent degeneration from the exterior to the interior between 1000h and 5000h of aging, decomposing into M23C6, α-(W,Mo), and W- and Mo-poor matrix. Due to the equilibrium segregation of W and Mo, α-(W,Mo) phase precipitated at grain boundary M23C6 after 5000h of aging. Changes in mechanical properties were mainly concentrated in the early aging stage. The increase in strength within the first 200h of aging was caused by a sharp rise in carbides, while the deterioration of ductility and toughness was attributed to the brittleness of intergranular M23C6 and its reduction of grain boundary cohesion. From 200h to 5000h of aging, the properties degraded gradually. The strength reduction in this stage was related to the weakening of solid solution strength by α phase and the coarsening of nanoscale M23C6, while the significant degradation of ductility and toughness was associated with the coarsening of intergranular M23C6 and the decomposition of M6C. The fracture mode transitioned from transgranular ductile fracture to a mixed mode after aging.

• From Withdrawal Rate to Creep Life: Microstructure-Mediated Performance in Directionally Solidified Mar-M247LC

  ganyisheng, wanghaiyang, zhonghong, zhujiaxi, libo, fengzhenyu, lishuangming

  Available online:December 09, 2025  DOI: 10.12442/j.issn.1002-185X.20250488

  Abstract(42) PDF(1.66 M)(56)

  Abstract:Directionally solidified (DS) nickel-based superalloys exhibit excellent creep resistance due to the elimination of transverse grain boundaries perpendicular to the stress axis. Given the strong dependence of creep performance on the initial solidification microstructure, this study reveals how withdrawal rate governs the as-cast microstructure of DS Mar-M247LC and dictates its post-heat-treatment creep life at 980 °C/220 MPa. It was found that an increase in the withdrawal rate of the directionally solidified specimens led to a reduction in the values of primary dendrite arm spacing (from 479 μm to 322 μm) and the average size of γ" precipitates (from 460 nm to 345 nm in interdendritic regions and from 298 nm to 203 nm in dendritic core). In addition, the carbide morphology changes from blocky to script-like. The heat treatment led to the formation of distinct cuboidal γ" precipitates and was accompanied by a significant increase in the γ" volume fraction compared to the directionally solidified microstructure. The alloy solidified at 40 μm/s exhibits elongated γ" rafts with narrowed matrix channels and regular dislocation networks, synergistically extending creep rupture life to 96.6 h. Fractographic analysis confirmed transgranular ductile, with fracture initiation occurring at decomposed MC carbides.

• 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(105) PDF(1.22 M)(214)

  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.

• Numerical simulations of dynamical relaxations in metallic glasses: a short review

  Claudio Fusco

  Available online:July 17, 2025  DOI: 10.12442/j.issn.1002-185X.20250367

  Abstract(77) PDF(2.73 M)(218)

  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.

• Stability and effect of primary carbides in Inconel 718 superalloy service turbine disk

  Zhang Yan Lin, Chen Shuo, Jiang He, Dong Jian Xin

  Available online:June 19, 2025  DOI: 10.12442/j.issn.1002-185X.20250173

  Abstract(149) PDF(2.76 M)(286)

  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.

• Effect of heat treatment on mechanical properties of TC4-0.55Fe titanium alloy tube

  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(180) PDF(2.69 M)(262)

  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.

• Study on Dynamic Mechanical Behavior and Low Temperature Mechanical Properties of Porous CoCrNi Medium-Entropy Alloy

  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(158) PDF(1.18 M)(296)

  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/m^₃ (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/m^₃, 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.

• Effects of Gas Regulation on the Characteristics of Nickel-Based and Titanium Alloy Powders prepared by EIGA

  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(142) PDF(1.37 M)(288)

  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.

• Shape topology optimization method for strain uniformity control of large disk forgings of superalloy

  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(90) PDF(1.10 M)(109)

  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.

• Prediction of Five Point Bending Rebound of TC4 Titanium Alloy Plate Based on Variable Elastic Modulus

  Qu Cong, Wang Dongjie

  Available online:November 20, 2024  DOI: 10.12442/j.issn.1002-185X.20240434

  Abstract(102) PDF(1.36 M)(105)

  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%.

• Development of ultra-coarse grained WC-8(Co,Ni) cemented carbides with varied Ni:Co ratios leveraging thermodynamic phase diagram calculations

  志伟 商, 志平 孙, 致明 王, 文凯 赵, 雅宁 陈

  Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.E20230047

  Abstract(180) PDF(1.23 M)(336)

  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.

• A new antibacterial and corrosion resistance coating on the AZ31 magnesium alloy prepared via friction stir processing combined with micro arc oxidation

  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(435) PDF(1.07 M)(586)

  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.

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