2026,Volume 55, Issue 10

>Special Issue：titanium alloy

• Preparation of Titanium-Based Alloys by Self-Propagating Aluminothermic Reduction of High-Titanium Slag

  Xie Wei, Dou Zhihe, Fang Shuai, Li Bingqi, Zhang Tingan

  2026,55(10):2421-2428 DOI: 10.12442/j.issn.1002-185X.20250638

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  Abstract:The effects of different aluminum ratios on the preparation of titanium-based alloys via aluminothermic reduction of high-titanium slag were investigated. Titanium-based alloys were prepared by self-propagating aluminothermic reduction using high-titanium slag, aluminum powder, KClO₃, and CaO as raw materials. The thermodynamics and kinetics of the aluminothermic reduction of high-titanium slag were calculated. The results show that high-titanium slag can be used to prepare titanium-based alloys via aluminothermic reduction. The main reaction is the reduction of TiO₂ by Al. The activation energy of the reaction is 274.4 kJ/mol, and the reaction order is 1.04. With the increase in aluminum ratio, the mass fraction of Ti element in the titanium-based alloy gradually decreases, and that of Al element gradually increases. At the same time, there are small amounts of alloying elements such as Fe, Mn, and Si in the titanium-based alloy. Phase analysis shows that under a low aluminum ratio, the main phase is Ti₃Al; under a high aluminum ratio, it is TiAl. The results of chemical composition analysis show that the prepared titanium-based alloy has a composition of 51.6wt% Ti, 40.6wt% Al, 7.6wt% Fe, 3.4wt% Mn, and 1.3wt% Si under the experimental conditions of aluminum ratio as 1.0. The microstructural analysis shows that the prepared titanium alloy consists of a base-phase region, an iron-rich phase region, and a silicon-rich phase region.

• A Strain-Compensated Arrhenius Model for TC18 Alloy Optimized via Genetic Algorithm and Response Surface Methodology

  Ding Shaoling, Wu Ming, Shi Shuangxi, An Hui, Zhang Yong

  2026,55(10):2429-2441 DOI: 10.12442/j.issn.1002-185X.20250547

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  Abstract:Accurate prediction of hot deformation behavior is critical for numerical simulation and intelligent manufacturing of titanium alloy forgings. The high-temperature deformation characteristics of TC18 titanium alloy were investigated using isothermal compression tests on a Gleeble-3800 thermal simulator over the temperature range of 720–840 °C and strain rate range of 0.001–1 s^–1. To precisely describe the flow behavior, three strain-compensated Arrhenius (SCA) constitutive models were developed and evaluated: a linear regression-fitted SCA (LR-SCA) model, a genetic algorithm-optimized SCA (GA-SCA) model, and a response surface-modified SCA (RS-SCA) model. The results demonstrate that genetic algorithm optimization effectively identifies global optimal parameters, while the response surface modification successfully accounts for the coupling effects of temperature and strain rate. Statistical evaluation reveals that the RS-SCA model achieves superior predictive capability, with a correlation coefficient (R) of 0.9980 and a mean absolute relative error of 2.16%, a significant improvement over the LR-SCA model's 7.01%. The reliability of the established RS-SCA model is further validated through its secondary development in DEFORM-3D, where finite-element simulations under stable processing conditions show excellent agreement with experimental load-displacement curves. This robust constitutive model provides a solid foundation for finite element simulation and process optimization of TC18 alloy components in thermomechanical processing applications.

• Effect of Microstructure on Typical Mechanical Properties of High-Temperature Titanium Alloy Ti650

  Zhou Wei, Hong Quan, Wang Xiao, Xin Shewei, Zhao Shengze, Hou Hongmiao, Yang Haiying, Yan Kang

  2026,55(10):2484-2490 DOI: 10.12442/j.issn.1002-185X.20250600

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  Abstract:The microstructural features of high-temperature titanium alloy Ti650 and their effects on mechanical properties were investigated. Results indicate that the S2-type (Ti,Zr)₆Si₃ silicide precipitates in the alloy exhibit no specific crystallographic orientation relationship with the matrix. Their morphology and distribution strongly depend on the microstructure type: in fine-lamellar Widmanst?tten structure, fine elliptical particles (20–60 nm) precipitate along the α/β interface; while in equiaxed, dual-phase, or coarse-lamellar Widmanst?tten structures, blocky silicides (approximately 200 nm) form within α grains. Room-temperature tensile tests reveal that equiaxed and dual-phase microstructures achieve the optimal strength-ductility balance (tensile strength of approximately 1100 MPa, elongation of approximately 13%). The fine-lamellar structure exhibits outstanding creep resistance at 650 °C and 100 MPa, with a steady-state creep rate nearly one order of magnitude lower than that of the equiaxed structure. Further mechanism analysis indicates that in the equiaxed structure, dislocations can traverse coarse silicide grains within the crystal via bypass mechanisms, allowing the creep process to persist. In contrast, fine spherical silicides are uniformly distributed within the lamellae and at grain boundaries. These silicides synergistically strengthen the lamellar structure, significantly increasing the energy barrier to dislocation motion and thereby conferring superior creep resistance on this microstructure.

• Simulation and Control of Forming Defects in Gel Casting of Yttria-Stabilized Ceramic Molds for Titanium Alloy

  Li Shuai, Ning Shuai, Ji Zhijun, Liu Yan, Zhang Weitao, Ding Xianfei, Nan Hai, Huang Kuidong, Fan Xueling, Lu Zhongliang, Li Dichen

  2026,55(10):2522-2532 DOI: 10.12442/j.issn.1002-185X.20250299

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  Abstract:To address nodular protrusions on titanium alloy-closed impellers caused by gas entrapment during gelcasting of integrated Y₂O₃ (yttria) ceramic molds, this work established a predictive and control framework that couples a Carreau non-Newtonian viscosity model with a transient two-phase volume-of-fluid filling solver. Rheological experiments were fitted to obtain the Carreau parameters for the yttria slurry (relative error < 5%), enabling time-space reconstruction of bubble generation-migration-entrapment throughout filling. Results show that the simulated entrapment locations exhibit strong spatial correspondence with computed-tomography voids in ceramic molds and nodular defects on Ti alloy castings at both the impeller and bottom regions. Parametric studies indicate that a moderate filling velocity of 0.05 m·s^–1 markedly reduces trapped-gas volume; a bottom-fill configuration essentially eliminates entrapment in the impeller region; on this basis, applying horizontal vibration (50 Hz, 1 mm) during and after filling removes the remaining bubbles. Ceramic molds fabricated with the optimized parameters were verified by scanning, confirming the disappearance of gas entrapment within the impeller. The study provides a reusable framework for defect prediction and active process control in gelcasting of complex Ti alloy components.

• Effect of Surface Nanogradient on Microstructure and Properties of Hot-Rolled Ti-6.5Al-2Zr-1Mo-1V Alloy

  Zhang Lingfeng, Wang Qianqian, Yu Hua, Xiong Yi, Jiang Tao, Zhang Jing

  2026,55(10):2533-2543 DOI: 10.12442/j.issn.1002-185X.20250317

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  Abstract:To address the failure caused by surface corrosion fatigue of titanium alloy structural components and to extend the service life of titanium alloys used in aircraft structures, supersonic fine particle bombardment (SFPB) technology was applied to the hot-rolled Ti-6.5Al-2Zr-1Mo-1V (TA15) alloy with varying impact durations. This process created a gradient nanostructure on the surface of the samples, and various instruments and equipment were used to study the effects on the microstructure, microscopic morphology, and mechanical properties after different treatment time. Results show that when the SFPB treatment time is 60 s, the surface average nanocrystal grain size of the hot-rolled structure is minimized, measuring 30.4 nm. The surface roughness of the treated samples increases compared to the original ones, and the minimum surface roughness is obtained after treatment for 60 s. However, longer impact times leads to the formation of microcracks on the sample surface. The SFPB treatment introduces high compressive residual stress on the sample surface, resulting in a significant increase in microhardness. After the SFPB treatment, the strength increases, with a slight decrease in elongation before stabilizing. With treatment time of 60 s, the best combination of strength and plasticity is achieved. The corrosion fatigue life of the SFPB-treated sample is improved by 12.7 times compared to the untreated sample. The SFPB treatment is able to generate a gradient nanolayer near the surface of the TA15 titanium alloy, significantly enhancing its tensile properties and corrosion fatigue life.

• Electro-induced Dynamic Globularization Kinetics of TA15 Alloy

  Yan Siliang, Liu Zilong, Li Junhui, Meng Miao, Huang Liang

  2026,55(10):2544-2552 DOI: 10.12442/j.issn.1002-185X.20250314

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  Abstract:The dynamic globularization behavior, law, mechanism, globularization kinetic curve and model of TA15 titanium alloy lamellar structure were studied by pulse current assisted compression test and quantitative analysis of metallographic structure. The results indicate that the increase in current density further aggravates the flow softening phenomenon. The globularization rate increases with the increase in current density and deformation. Based on the Avrami equation, a dynamic electro-induced globularization kinetics model for TA15 alloy is established. The model predicts that the ranges of the critical strain ε_c for dynamic spheroidization and the strain ε_f for completing dynamic spheroidization are 0.090–0.187 and 5.02–6.31, respectively, and both decrease with the increase in current density. The globularization kinetics rate increases first and then decreases with the increase in strain and current density. In addition, the higher the current density, the greater the peak value of the spheroidization kinetics rate and the smaller the strain corresponding to the peak value.

• Numerical Simulation of Solidification Structure in Industrial-Scale Ti-1023 Alloy Ingots

  Wang Yangyang, Liu Xianghong, Wang Qing, Wu Jiangtao, Xia Yong, Zhao Xiaohua, Fu Jie

  2026,55(10):2573-2578 DOI: 10.12442/j.issn.1002-185X.20250361

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  Abstract:A numerical model was established using the finite volume method to establish a corresponding relationship between the simulated temperature with flow fields and the actual solidification structure of the ingot. The grain growth direction and grain morphology transformation of the industrial-scale Ti-1023 alloy ingot were investigated. The results indicate that the predicted grain growth direction (angle) of columnar grain at the bottom and edges of the ingot agrees with the actual one with coincidence degree more than 90% through temperature gradient components and . The temperature gradient-solidification rate (G-R) diagram was plotted. There is an obvious boundary between equiaxed and columnar grains, and the critical parameter G* for columnar-equiaxed crystal transformation varies under different melting processes.

• Influence of Rare Earth Y on High-Temperature Oxidation Behavior of Mn-Containing β-Solidified γ-TiAl Alloys

  Zuo Huichao, Hao Junjie, Xue Peng, Chen Bo, Wang Jianjun, Li Xiaobing, Liu Kui

  2026,55(10):2590-2598 DOI: 10.12442/j.issn.1002-185X.20250377

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  Abstract:The influence of trace amounts of rare earth element Y on the high-temperature oxidation resistance was investigated for low-cost and easily deformable Ti44Al3Mn0.4W0.4Mo0.1B0.1C(TMMW) alloy at 800 °C. The microstructure and oxide film of the alloy were analyzed using EPMA, XRD, and TEM, and the underlying mechanisms of element Y affecting the high-temperature oxidation resistance of the alloy were explored. Results indicate that the addition of a trace amount of Y exerts a certain impact on the microstructure of the alloy. After identical heat treatment, the Y-free alloy primarily consists of γ, α₂, and β_o phases, whereas the Y-containing alloy not only contains these phases but also exhibits precipitation of the YAl₂ phase at lamellar boundaries and within the matrix, with minimal formation of Y₂O₃. Cyclic oxidation kinetics tests reveal that the oxide film formed on both alloys comprises a three-layer composite structure: TiO₂/Al₂O₃/TiO₂+Al₂O₃, with the transition layer mainly composed of TiMn₂-Laves phase and a small quantity of Mo- and W-rich β_o phase. The addition of 0.3at%Y effectively reduces oxidation mass gain, enhances spallation resistance of the oxide scale, and significantly decreases the βo phase content in the transition layer.

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

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

  2026,55(10):2608-2620 DOI: 10.12442/j.issn.1002-185X.20250391

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  Abstract:To further enhance low-temperature toughness and clarify the low-temperature fracture failure mechanisms of titanium alloys, a TC4-0.55Fe alloy was prepared by micro-alloying with Fe, and its impact performance and fracture behavior were systematically investigated over the temperature range 20 ℃ to –196 ℃. The alloy exhibits a Charpy impact toughness of 66.8 J·cm^–2 at 20 ℃, which remains unchanged as the temperature drops to –20 ℃. When the temperature drops to –70 ℃, the low-temperature toughness decreases to 46.8 J ·cm^–2. When the temperature drops to –196 ℃, the toughness still retains 25.1 J·cm^–2, which is 23.8% higher than that of TC4 alloy. SEM image of fracture confirms that –196 ℃ is still above ductile-brittle transition temperature. of the alloy 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 fine-grain strengthening, the dispersion of fine acicular α_s precipitates within the β matrix, and a significant increase in twin density at low temperature, which jointly promote crack-path deflection and significantly enhance resistance to fracture.

>Special Issue：High Temperature Alloy

• Effect of Carbon Content on Microstructure and Mechanical Properties of a Novel Wrought Nickel-Based Superalloy

  Liu Wenli, Zhao Xia, Hou Kunlei, Wang Yifei, Wang Ping, Ma Yingche, Hao Xianchao, Ou Meiqiong

  2026,55(10):2463-2475 DOI: 10.12442/j.issn.1002-185X.20250507

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  Abstract:Carbon (C), as a crucial trace element in nickel-based superalloys, exerts a significant influence on mechanical properties even with minor variations in content. This study investigated the effect of C content on the microstructure and mechanical properties of a novel nickel-based superalloy GH4750. The results demonstrate that with increasing C content from 0.024wt% to 0.042wt% and then to 0.082wt%, the quantity and average size of M_C carbides increase. These carbides can effectively pin grain boundaries, resulting in a progressive reduction in grain size from approximately 35 μm to approximately 31 μm and ultimately to approximately 22 μm. Both the room-temperature and 750 °C tensile strengths initially increase and then decrease as the C content increases. Conversely, the elongation displays the opposite trend. The differences in tensile properties are closely related to the carbide characteristics. An appropriate increase in carbide content can inhibit the formation and coalescence of microvoids, effectively pin grain boundaries, and prevent grain boundary slip at elevated temperatures. Excessive carbides act as preferential sites for microcrack initiation. The stress-rupture life decreases with increasing C content, attributed to the larger grain size. Based on comprehensive consideration, the optimal C content for the novel nickel-based superalloy GH4750 is determined to be 0.042wt%.

• Research on Segmentation Algorithm for GH4169 Alloy Grains Based on a Joint Attention Mechanism

  Deng Bowen, Li Ke, Zhang Xinyuan, Zhao Yanru, Shi Puying, Wang Hu, Gao Huixian, Yang Chao

  2026,55(10):2565-2572 DOI: 10.12442/j.issn.1002-185X.20250360

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  Abstract:To tackle the segmentation challenges arising from the complex morphology, significant size variations, blurred boundaries, and tight interconnections of superalloy grains, this research presents a grain segmentation network integrated with a joint suppression attention mechanism that fuses channel and spatial information. The proposed network combines the global modeling capacity of Swin Transformer and the local detail restoration capability of a convolutional neural network (CNN), and embeds the aforementioned joint suppression attention mechanism, which integrates channel and spatial information, into the decoder. Results show that this mechanism effectively suppresses noise and texture interference, enhances the abilities of feature screening and generalization, and reinforces the fusion of shallow and deep features, thereby markedly improving the continuity of grain boundaries. Experimental results demonstrate that the proposed algorithm achieves an IoU of 67.34% and an F1-score of 78.62% on the self-constructed metallographic dataset, with all metrics outperforming those of mainstream grain segmentation algorithms for superalloys.

• Study on Degradation Mechanisms and Rejuvenation Processes for Microstructure and Properties of Gas Turbine Blades

  Sun Haohua, Zhang Jianting, Cui Jinyan, Xiao Lei, Guo Jianzheng

  2026,55(10):2579-2589 DOI: 10.12442/j.issn.1002-185X.20250376

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  Abstract:Degradation behavior of the microstructure and mechanical properties of a long time serviced GTD111 DS superalloy turbine blade was investigated. Rejuvenation heat treatment was subsequently applied using a treatment of hot isostatic pressing (HIP) followed by solution and double-aging treatments. The results demonstrate that during service, pore density increases significantly from blade tip to root; MC carbides decompose into M₂₃C₆ carbides and η phase; secondary γ′ precipitates undergo severe spheroidization and rafting, accompanied by the dissolution of tertiary γ′ precipitates. The overall microstructural degradation pattern along the blade longitudinal axis follows the order: tip>central region>root>tenon. Along the transverse axis, it follows the order: trailing edge>leading edge>suction side>pressure side. The microstructure degradation directly leads to a progressive reduction in ultimate tensile strength at 25 and 980 °C and stress rupture life at 980 °C/220 MPa from the tenon to the blade tip. After rejuvenation heat treatment, the microstructure and mechanical properties are markedly improved. Area fraction of microporosity at the blade tip is reduced, MC carbides are partially restored, and the sizes of secondary and tertiary γ′ precipitates decrease to approximately 0.5 μm and 59 nm, respectively. Ultimate tensile strength of the blade tip increases from 810 MPa to 1122 MPa at room temperature and from 388 MPa to 468 MPa at 980 °C; the stress rupture life (980 °C/220 MPa) is prolonged from 1.95 h to 11.31 h. After rejuvenation, all mechanical properties at the blade tip exceed those of the tenon region.

• Effects of Co and C on Microstructure and Aging Stability of a New Type Hot-Corrosion-Resistant Nickel-Based Single-Crystal Superalloy

  Wang Jiayu, Liu Enze, Tan Zheng, Tong Jian, Liu Weihua, Li Haiying, Xin Xin, Jia Dan, Liu Yichuan, Tu Ganfeng, Xiao Faxin, Sun Shuchen, Mao Chengrong, Ning Likui

  2026,55(10):2599-2607 DOI: 10.12442/j.issn.1002-185X.20250379

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  Abstract:The effects of Co and C on microstructural characteristics and stability during long-term aging at 1000 °C in a novel hot-corrosion- resistant Ni-based single-crystal superalloy were investigated. Four single-crystal alloys with varying Co and C contents were prepared via directional solidification and characterized by SEM, EDS, EPMA, and TEM. The results show that C suppresses solidification micropores and reduces γ/γ′ eutectic fraction by promoting the precipitation of MC-type carbides, such as TaC. Co enhances the solid solubility of the γ-matrix, effectively inhibiting the segregation of Re, W, Ta, and Al, while carbides reduce the homogenization efficiency. Co lowers the γ′ solvus temperature and refines the size of γ′ precipitates, while C increases the solvus temperature and promotes γ′ coarsening due to the release of γ′-forming elements during carbide dissolution. During long-term aging, γ′ coarsening follows Lifshitz-Slyozov-Wagner (LSW) kinetics. Both Co and C reduce the absolute value of the γ/γ′ lattice misfit and increase the effective diffusion coefficient (D_eff). Co reduces the γ′ coarsening rates, while C accelerates it. The misfit dominates coarsening at fixed C content, whereas D_eff governs it at fixed Co content. Predictions from three models for topologically close-packed (TCP) phase precipitation show discrepancies with experimental data: Co promotes TCP formation, while C inhibits it through consuming MC carbides consisting of Mo and W.

>Materials Science

• Molecular Dynamics Simulations of Aluminum-Based Core-Shell Nanocomposite with Carbon Coating Under Linear Injection of Heat Energy

  Liu Hongbo, Li Aojie, Ma Wenjiang, Chen Zhanghua, Liu Yi

  2026,55(10):2442-2449 DOI: 10.12442/j.issn.1002-185X.20250491

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  Abstract:A novel core-shell nanocomposite was prepared by coating carbon onto aluminum nanoparticles (ANPs). As a typical energetic material, this nanocomposite absorbs the heat energy prior to ignition and combustion. Molecular dynamics simulations were used to elucidate the phase-transition mechanism of the nanocomposite upon heating and to analyze migration at the core-shell boundary. The results show that the critical melting point of carbon-coated ANPs (8 nm in diameter), at which the material transitions from solid to liquid, is approximately 1050 K. The interatomic potential energy of nanocomposites is lower than that of aluminum cores. Therefore, upon injection of thermal energy, the initial amorphous phase transforms into the liquid phase, which then diffuses from the surface to the core. Low interatomic potential energy leads to an earlier transition to the liquid phase. Furthermore, the core-shell ratio is the main factor affecting the critical melting point. The higher the core-shell ratio, that is, the thinner the carbon coating, the lower the melting point. Therefore, effectively controlling this parameter is an important indicator of ignition efficiency.

• Arc-Erosion Behavior and Mechanism of Ag/ZnO/La₂Sn₂O₇ Composites in N₂, CO₂ and Their Mixtures with c-C₄F₈

  Bao Mengting, Guo Ke, Jiang Yun, Wang Bingtang, Liu Zhuhan, Feng Yi

  2026,55(10):2450-2462 DOI: 10.12442/j.issn.1002-185X.20250462

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  Abstract:La₂Sn₂O₇ powder was synthesized via chemical co-precipitation, and the Ag/ZnO/La₂Sn₂O₇ composites were prepared by hot-pressed sintering. The arc-erosion behavior and mechanisms of the composites were investigated at a constant voltage of 7 kV in CO₂, N₂, CO₂/c-C₄F₈, and N₂/c-C₄F₈ mixtures. The results show that the difference in arc breakdown current is very small across different atmospheres, while the erosion area, arc energy, and arc duration in mixed gas are clearly smaller than those in CO₂ and N₂. As the content of c-C₄F₈ rises, the breakdown strength in mixed gas increases gradually and is higher than that in CO₂ and N₂. The optical images of the arc show that the arc volume in mixed gas is obviously smaller than that in single-gas CO₂ or N₂, and the arc volume decreases gradually with the increase in c-C₄F₈ content. The erosion morphology analysis indicates that more pores, spattered particles, and cracks are present in the composites after arc-erosion in CO₂ and N₂. In the gas mixture, the erosion area is the smallest in the N₂/c-C₄F₈ (80/20) mixture, and particles and pores are significantly reduced. The low arc energy observed in N₂/c-C₄F₈ mixtures significantly reduces arc volume and erosion area. X-ray photoelectron spectroscopy results reveal partial decomposition of La₂Sn₂O₇ into La₂O₃ and SnO₂, while AgF and CF_x compounds are identified on eroded surfaces in c-C₄F₈ containing mixtures.

• Enhancing Microstructure and Mechanical Properties of As-Cast Mg-12Gd-0.5Zr Alloys via Ultrasonic Treatment

  Zhong Hao, Dong Xiongbo, Yang Wei, Wang Xueyi, Ma Zhijun, Yang Zhong

  2026,55(10):2476-2483 DOI: 10.12442/j.issn.1002-185X.20250556

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  Abstract:The influence of ultrasonic treatment on the microstructure and tensile properties of as-cast Mg-12Gd-0.5Zr alloys was examined. The results indicate that ultrasonic treatment markedly refines the α-Mg grain structure, with the finest grains observed at an input power of 1500 W. This grain refinement is attributed to the combined effects of cavitation and acoustic streaming, which promote heterogeneous nucleation. Furthermore, the treatment reduces the size and number of the secondary Mg₅Gd phase while enhancing its spatial uniformity. A considerable dissolution of Gd atoms into the α-Mg matrix is also observed, likely due to the suppression of Gd segregation by acoustic streaming. Correspondingly, ultrasonic treatment yields notable improvements in ultimate tensile strength, yield strength, and elongation at room temperature. These improvements are primarily attributed to the refined microstructure and the increased solid solubility of Gd within the matrix.

• Novel Constant-Strain-Rate Backward Extrusion for AZ91 Magnesium Alloy

  Zhang Pengtao, Cheng Xiaole, Ren Xijun, Zhang Min, Bian Chenghao, Sun Jian, Zhao Xiaohui, Su Zhenhua

  2026,55(10):2491-2500 DOI: 10.12442/j.issn.1002-185X.20250389

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  Abstract:To overcome the limitations of poor room-temperature ductility and significant anisotropy in AZ91 magnesium alloy, a constant-strain-rate backward extrusion (CSR-BE) process was introduced to enhance deformation homogeneity through synergistic regulation of die curvature and strain rate. The methodology employs axisymmetric slip-line theory, combined with volume constancy principles, to derive a die profile equation that enables precise control of strain rates throughout deformation. Comprehensive DEFORM-3D simulations reveal that CSR-BE achieves a 9.3% reduction in extrusion force compared to conventional backward extrusion, accompanied by substantial improvements in deformation uniformity: a 99.96% decrease in flow velocity variance, an 85.2% reduction in stress field variation, and an 81.6% mitigation of temperature distribution fluctuations. Mechanistic analysis demonstrates that the optimized die geometry shifts the material flow dominance from radial shear to axial stretching, characterized by a decrease in the slip-line orientation angle from 36.27° at the inlet to 11.3° at the outlet. The engineered hydrostatic pressure gradient effectively alleviates localized stress concentrations, eliminates friction-induced dead zones, and suppresses strain-rate variations. Quantitative stress and flow-rate calculations confirm that this approach fundamentally addresses the microstructural heterogeneity inherent to traditional extrusion methods. CSR-BE process establishes a theoretically grounded manufacturing strategy for producing high-performance magnesium alloy rods with enhanced isotropy, demonstrating significant potential for industrial-scale applications through its combined efficiency and microstructural control advantages.

• 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

  2026,55(10):2501-2510 DOI: 10.12442/j.issn.1002-185X.20250285

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  Abstract: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 applications restricted in the field of water cooling in electronic packaging. In this research, the sintering performance between the green body and the composite plate was enhanced by employing a silver doping strategy, thereby addressing the thermal management challenges in electronic packaging. Composite base plates and pin-fin type composite base plates were prepared, and their application benefits were evaluated in both indirect and direct water cooling scenarios. Results demonstrate that the silver-doped copper billet achieves 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 reduce the temperature of the heating sheet by 5–6 °C and 4–5 °C during water-cooling tests respectively. The numerical simulation results are in good agreement with the experimental data, confirming the excellent thermal uniformity of the composite structures. This research successfully overcomes the limitations associated with the low thermal conductivity of traditional packaging components and the challenges in fabricating complex structures using diamond/copper composite materials.

• Effect of Heat Treatment Parameters on the Microstructure and Properties of 2195 Aluminum-Lithium Alloy

  Jia Xiangdong, Zhang Hongyao, Hao Kunming, Hu Gang, Lu Wei

  2026,55(10):2511-2521 DOI: 10.12442/j.issn.1002-185X.20250630

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  Abstract:To investigate the influence of solution and aging parameters on the strengthening and toughening mechanisms of 2195 Al-Li alloy, orthogonal experiments combined with range analysis were conducted. The regulatory rules of heat treatment regimes on the mechanical properties and microstructure of the alloy were illustrated. The results indicate that during solution treatment process, the 2195 Al-Li alloy exhibits significantly higher sensitivity to solution temperature than to solution time. Thus, to design the solution process, the appropriate solution temperature should be given priority consideration, followed by optimization of the corresponding holding time based on this temperature. In the aging stage, the strengthening effect of the 2195 Al-Li alloy is primarily dominated by the T₁ phase, and its precipitation behavior is strictly regulated by aging temperature and time. Under natural aging (under-aged state), the precipitated phases are predominantly δ′ phases, resulting in a relatively limited strengthening effect. At the peak aging stage, the T₁ phases exhibit characteristics of fine size, dispersion, and high density, and at this time, the strength of the alloy achieves its maximum value. Upon entering the over-aged stage, the coarsening of T₁ and δ′ phases lead to a decrease in alloy strength. Consequently, precise control of aging parameters provides an effective means of tailoring the type, size, and spatial distribution of strengthening precipitates, thereby optimizing the comprehensive mechanical properties of the 2195 Al-Li alloy to meet the requirements of its forming processes and structural applications.

• Effect of Y₂O₃ Content on Microstructure and Properties of Stellite 6 +Y₂O₃ Laser Cladding Layers on Surface of 17-4PH Steel

  Shang Xiaofeng, Zhu Qingyong, Jia Ye, He Chen, Zhao Yuhui, Zhao Jibin

  2026,55(10):2553-2564 DOI: 10.12442/j.issn.1002-185X.20250356

  Abstract(11) HTML(0) PDF(17.44 M)( 0)

  Abstract:In this study, wear-resistant and corrosion-resistant cobalt-based Stellite 6 coating were fabricated on 17-4PH steel by laser cladding with varying Y₂O₃ content (0wt%, 0.3wt%, 0.6wt%, and 0.9wt%). The effects of Y₂O₃ addition on the microstructure, microhardness, wear resistance, and corrosion resistance of the laser-cladded Stellite 6 samples were investigated. The results indicate that the addition of Y₂O₃ changes the grain structure from coarse columnar grains to fine, uniform equiaxed grains. The sample with 0.6wt% of Y₂O₃ exhibits an average grain size of 54.6 μm, representing a maximum grain refinement of 66.0% compared to the sample without of Y₂O₃ addition. Furthermore, Y₂O₃ particles are mainly dispersed in the interdendritic regions of the Stellite 6 alloy samples, forming a particle layer in front of the dendrite grains, which inhibits grain movement and solute atom diffusion. The sample with 0.6wt% of Y₂O₃ addition shows the highest microhardness, with an average value of 532 HV. Due to the smallest grain size and spacing between Y₂O₃ particles, it also demonstrates the best wear resistance and corrosion resistance performance. Compared to the sample without Y₂O₃ addition, the maximum microhardness increases by 22.6%, the wear rate decreases by 72.2%, the corrosion potential increases by 25.6%, and the corrosion current density decreases by 39.8%.

• Microstructure and Thermionic Emission Properties of (La_0.5Ba_0.5) B₆-VB₂ Cathode

  Yang Xinyu, Wang Zixuan, Li Zimeng, Cheng Hefa, Zhao Wei, Wang Yan, Luo Shifeng, Han Cuiliu, Zhang Jiuxing

  2026,55(10):2621-2628 DOI: 10.12442/j.issn.1002-185X.20250342

  Abstract(11) HTML(0) PDF(5.71 M)( 3)

  Abstract:Lanthanum hexaboride (LaB₆) is an excellent high-temperature ceramic material for thermionic cathodes. However, the high brittleness of LaB₆ makes it difficult to process, limiting the further engineering application. In this study, Barium hexaboride (BaB₆) with low work function and Vanadium diboride (VB₂) with high elastic modulus were added into LaB₆. (La_0.5Ba_0.5)B₆-VB₂ composite with the high relative density of 98.57%, whose matrix is a single-phase solid solution, was prepared by spark plasma sintering (SPS) under the conditions of 1900 ℃, 40 MPa, and 5 min. As the sintering temperature increases from 1500 ℃ to 1900 ℃, the average grain size of the composite increases from 2.68±1.44 μm to 7.21±1.37 μm, Vickers hardness increases from 16.57±0.88 GPa to 24.89±1.26 GPa, fracture toughness increases from 1.95±0.16 MPa·m^1/2 to 3.81±0.28 MPa·m^1/2, and the maximum bending strength reaches 376.32 MPa. Crack deflection and branching are identified as the primary toughening mechanisms in the composite. (La_0.5Ba_0.5)B₆-VB₂ composite exhibits the maximum current density of 7.56 A/cm² and the minimum work function of 2.97 eV.

• Machine Learning-Assisted Design of Interpretable Models for TiZr-Based High-Entropy Alloys Used in Armor-Piercing Applications

  Luo Hao, Liu Tianyu, Wei Huanan, Gao Xingyong, Fan Feigao, Zhai Anqi, Liu Zhuo

  2026,55(10):2629-2638 DOI: 10.12442/j.issn.1002-185X.20250385

  Abstract(4) HTML(7) PDF(2.39 M)( 2)

  Abstract:TiZr-based refractory high-entropy alloys (RHEAs), known for their high hardness, compressive strength, and thermal phase stability, have garnered attention due to their potential application in armor-piercing warheads. This study introduced a machine learning (ML)-assisted approach to alloy design, aiming to uncover the complex relationships between composition and performance and to improve design efficiency. To address the critical requirement for hardness in armor-piercing applications, a 15-dimensional feature dataset was constructed from 157 experimental hardness data points, incorporating component molar fractions and five key descriptors. Eight ML models, including random forest, K-nearest neighbors, and support vector machines were trained, and XGBoost was identified as the most accurate through hyperparameter tuning via grid search and cross-validation. The SHAP (Shapley additive explanations) framework was applied to interpret feature contributions. Results indicate that the XGBoost model achieves the highest predictive performance (R2=0.73, and the average absolute percentage error is 14.0%). The most influential factors affecting alloy hardness are mixing enthalpy (), Nb content, and atomic size mismatch (). Effective hardness control relies on the synergistic regulation of thermodynamic stability, electronic structure, and geometric dimensions, where inter-feature compensation plays a critical role in optimizing overall performance.

>Reviews

• Research Progress on Room-Temperature Discontinuous Yielding Behavior of Metal Materials

  Fan Yurong, Xue Xiangyi, Lai Minjie, Li Jinshan, Luo Ting

  2026,55(10):2639-2651 DOI: 10.12442/j.issn.1002-185X.20250297

  Abstract(8) HTML(7) PDF(5.24 M)( 7)

  Abstract:Discontinuous yielding of metal materials during room-temperature deformation is a critical scientific issue that significantly affects their mechanical properties and application safety. This review summarized recent research advancements in this field, with a focus on the characteristics, influencing factors, and underlying mechanisms of discontinuous yielding. The discontinuous yielding phenomenon was mainly characterized by a yield drop and a stress plateau on the stress-strain curve. Results show that microstructural characteristics such as alloy composition, degree of recrystallization, grain size and morphology, as well as phase composition and stability, serve as primary factors influencing discontinuous yielding. These factors affect the yielding behavior by regulating dislocation movement and deformation mechanisms. Furthermore, the intrinsic relationship among discontinuous yielding, room-temperature deformation mechanism, and the work hardening behavior in metallic materials was explored. Based on current research, future studies should focus on the microstructure regulation, alloy design, deformation mechanisms, and the development of constitutive models to deepen the understanding of discontinuous yielding and to provide a foundation for optimizing material properties.

• Research Progress on Laser Cladding WC-Co Coatings and its Wear Resistance

  Qu Kepeng, Zhao Mingyue, Wang Nan, Zhai Qixun, Chen Yongnan, Zhao Yongqing

  2026,55(10):2652-2664 DOI: 10.12442/j.issn.1002-185X.20250348

  Abstract(4) HTML(4) PDF(11.92 M)( 5)

  Abstract:Laser cladding is widely employed for surface strengthening of titanium alloys and other metals owing to its advantageous metallurgical bonding and narrow heat-affected zones. Among various strengthening materials, WC is used as a superhard ceramic phase. Through its synergistic effect with Co, the hardness and wear resistance of the cladding layer can be effectively enhanced. However, research has demonstrated that laser power exerts a significant influence on cladding layer quality. When excessive power is applied, excessive dissolution of WC particles occurs, facilitating crack initiation and pore formation. Conversely, insufficient power commonly leads to defects, such as unmelted particles and porosity. This review focused on the influence of laser power on WC grain size and growth mechanisms within the coating, and summarized the wear resistance mechanisms of the coating. Furthermore, the main limitations currently encountered in the preparation of WC-Co coatings were analyzed, along with corresponding improvement strategies. Finally, existing challenges and future development trends were discussed.

• Research Status of Nickel-Based Superalloys Repaired by Laser Directed Energy Deposition

  Wang Qingzheng, Xiao Junfeng, Lin Xin, Tang Wenshu, Gao Song, Liu Quanming, Chai Haozhi

  2026,55(10):2665-2686 DOI: 10.12442/j.issn.1002-185X.20250302

  Abstract(11) HTML(0) PDF(6.15 M)( 7)

  Abstract:Nickel-based superalloys are widely used in critical hot-section components of high-end equipment such as aero-engines and gas turbines due to their excellent mechanical properties and oxidation resistance at elevated temperatures. As an advanced manufacturing method, laser directed energy deposition (L-DED) has demonstrated great potential in the repair of complex components, owing to its advantages such as mold-free near-net shaping, controllable energy input, small heat-affected zone, and dense microstructure in the deposited layer. However, during L-DED repair process, nickel-based superalloys undergo complex rapid melting and solidification, as well as repeated thermal cycling, resulting in unique microstructural features and a high tendency to develop typical metallurgical defects, such as pores, cracks, stray grains, and microstructure degradation, which can significantly degrade their mechanical performance. The typical defects and their control methods, as well as microstructural evolution characteristics were reviewed, and the key mechanical properties, including room-temperature tensile strength, high-temperature creep resistance, and fatigue performance, between directly deposited and repaired nickel-based superalloys were compared. Furthermore, based on existing theoretical models, the mechanisms of defect formation and microstructural evolution were analyzed, highlighting the current technical challenges and limitations in this field. This review provides a theoretical foundation and direction for the process optimization, microstructural control, and performance enhancement of L-DED-repaired or L-DED-formed nickel-based superalloys.

• Research and Development in GH3536 Superalloy Processed by Laser Additive Manufacturing

  Hao Mingsong, Zhou Lin, Wang Guan, Wang Kai, Liang Jingjing, Li Jinguo

  2026,55(10):2687-2712 DOI: 10.12442/j.issn.1002-185X.20250386

  Abstract(11) HTML(0) PDF(20.35 M)( 1)

  Abstract:Laser additive manufacturing, as an advanced digital forming technology, is widely used in the research of superalloy preparation. GH3536, as a solid solution strengthened nickel-based superalloy, is suitable for the preparation of components for combustion chambers of aero-engines due to its excellent mechanical properties. The control of metallurgical defects, microstructure modulation and mechanical property strengthening mechanism of laser additive manufacturing of GH3536 alloy were reviewed. The current research status and progress of laser additive manufacturing for GH3536 alloy were analyzed, and the research on the influence mechanism of its tensile and creep properties and other research was expected. It is hoped to provide reference for the research and development of laser additive manufacturing for GH3536 alloy.

Online First

• Recrystallization and Texture Evolution of Ultra-High-Strength Titanium Alloys During Thermal Deformation in the β Single-Phase Region

  Bo-dong Wang, Bo-zhi Yang, Hui Zhang, Jian-wei Xu, Wei-dong Zeng

  Available online:August 13, 2026  DOI: 10.12442/j.issn.1002-185X.20260061

  Abstract(67) PDF(1.32 M)(32)

  Abstract:This study investigates the recrystallization behavior and texture evolution of ultra-high-strength TB17 titanium alloy during thermal deformation in the β single-phase region through isothermal hot compression experiments combined with EBSD analysis. Results indicate that as strain increases, grains gradually elongate from equiaxed shapes, while the geometric necessary dislocation density significantly rises and accumulates near grain boundaries and second-phase particles, providing nucleation driving forces for recrystallization. Dynamic recrystallization predominantly occurs as continuous dynamic recrystallization (CDRX), nucleating and growing along grain boundaries and within grains through subgrain rotation, coalescence, and grain boundary migration. Discontinuous dynamic recrystallization (DDRX) occurs only at trifurcated grain boundaries and increases gradually with strain. During low strain, orientation dispersion occurs with {110}<111> slip dominating. At high strain, a strong <001> and <111> twin texture forms, and the activation of the {112}<111> slip system significantly increases, evolving synergistically with the CDRX process. Controlling deformation magnitude effectively optimizes recrystallization extent and texture type, providing theoretical basis for developing hot working processes for this alloy.

• Optimization of Precision Hot Forging Process for High-Strength Aluminum Alloy Wheel Hubs Based on Simulation-Experiment Coupling

  Guo Guixing, Huang Xiaomin, Sun Fu, Wu Weiqi, Mao Qilin, Ji Hongchao

  Available online:August 13, 2026  DOI: 10.12442/j.issn.1002-185X.20260162

  Abstract(54) PDF(1.72 M)(32)

  Abstract:In response to the susceptibility of conventional cast wheels to forming defects and the high demand for energy conservation and emission reduction in modern vehicles, a two-stage precision hot forging process was designed to fabricate high-strength and lightweight 7050 aluminum alloy wheels. The hot deformation characteristics of 7050 aluminum alloy billets were systematically examined through isothermal hot compression tests. Finite element models for the pre-forging and final-forging operations were developed via Deform-3D software to conduct full-process numerical simulations of the wheel hub hot forging process and analyze the distribution characteristics of various physical field variables. A mathematical regression model was constructed based on the response surface methodology. Aiming at the dual objectives of reducing forging load and minimizing forging damage, key process parameters including initial forging temperature, die forging speed, and friction coefficient were optimized. The optimization outcomes demonstrated that the peak loads in the pre-forging and final-forging stages were reduced by 22.46% and 13.26%, respectively. The maximum damage zone of the forging was significantly reduced, and the overall damage level was remarkably lowered. Forging experiments were performed under the optimal process parameters, and the forgings exhibited excellent forming quality with comprehensive properties meeting industrial technical requirements.

• Study on mechanical and biological properties of Ti-based diamond composite materials formed by Selective Laser Melting

  Jiang Xiaopeng, Xu Yangli, Zheng Xinyan, Mu Jianan, Cao Xuanyang, Guo Zihuan, Hidetoshi Saitoh

  Available online:August 13, 2026  DOI: 10.12442/j.issn.1002-185X.20260174

  Abstract(58) PDF(1.38 M)(32)

  Abstract:Aiming at the lack of antibacterial activity in clinical applications of porous structures made of medical titanium alloy (Ti6Al4V) by laser additive manufacturing, Ti-based diamond composites were fabricated in this study using selective laser melting (SLM) technology, and a systematic investigation of their biological and mechanical properties was conducted. With parameters set at a laser power of 200 W, a scanning speed of 1200 mm/s, scanning hatch of 0.12 mm, Ti-based diamond composite materials and their porous lattice structures with good surface quality and uniform diamond distribution are successfully prepared. The biological performance tests showed that, through the antibacterial performance experiments using Staphylococcus aureus and Escherichia coli, and the in vitro compatibility experiments using mouse embryonic osteoblast precursor cells confirmed that the surface of samples from the proposed method have excellent antibacterial properties and high biocompatibility. Mechanical tests show that the compressive strength and elastic modulus of porous lattice structures with porosities of 50%, 60% and 70% were measured as 119.69±8.00 MPa and 3.09±0.07 GPa, 59.48±0.81 MPa and 1.84±0.06 GPa, 12.84±0.72 MPa and 0.68±0.03 GPa. The compression deformation mechanism of porous lattice structures with 50% and 60% porosity is characterized by fracture failure along a 45° inclined plane, whereas the structure with 70% porosity failed through layer-by-layer fracture. The Gibson-Ashby mathematical model was established to describe the relationship between porosity and mechanical properties, and is found to be highly compatible with the mechanical properties of human bone.

• Study on the Steam Oxidation Behavior of Nickel-Based Superalloy CM247LC

  Che Xueyu, Xuan weidong, Zhao Dan, Liu Ming, Yin Minghui, Ren Zhongming

  Available online:July 14, 2026  DOI: 10.12442/j.issn.1002-185X.20260141

  Abstract(109) PDF(2.18 M)(80)

  Abstract:A systematic investigation was conducted on the oxidation behavior of nickel-based superalloy CM247LC at 1100 ℃ for 2 h under different water vapor contents. The surface and cross-sectional morphologies, phase composition, and formation mechanism of the oxide scale were analyzed by means of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and thermodynamic calculations. The results indicate that water vapor significantly accelerates the oxidation of CM247LC alloy. As the water vapor content increases, the oxidation weight gain intensifies and the oxide scale thickness gradually rises. The surface oxide scale evolves from fine and uniform oxide particles into coarse particles, which subsequently agglomerate to form a continuous oxide layer. The oxide scale exhibits a multi-layer structure, primarily composed of NiO、Cr₂O₃、HfO₂、TiTaO₄、CoCr₂O₄ and Al-rich oxides. The formation sequence of these oxides is consistent with the order of their Gibbs free energies of formation. Water vapor promotes the growth of oxides and induces spallation of the oxide scale, thereby deteriorating the oxidation resistance of the alloy.

• Interfacial Microstructure and Mechanical Properties of High-Nitrogen Steel/Alumina Ceramic Heterogeneous Brazed Joints

  Chang Jiashuo, Wang Xingxing, Wu Gang, Wang Shuai, Rocco Lupoi, Mohamed Rachik, Zhang Guanxing, Chang Yunfeng

  Available online:July 14, 2026  DOI: 10.12442/j.issn.1002-185X.20260169

  Abstract(100) PDF(1.03 M)(82)

  Abstract:To investigate a reliable joining method for heterogeneous joints between high-nitrogen steel and alumina ceramic, vacuum brazing of P580 high-nitrogen steel and alumina ceramic was carried out using AgCuTi filler metal. The influence of brazing temperature on the interfacial microstructure and mechanical properties of the joint was systematically analyzed. The results show that the optimal joint was obtained under the process parameter of 910 °C/10 min. Its interfacial structure was Al2O3/Cu3Ti3O/Ag(s,s)+Cu(s,s)+TiCu/TiN/high-nitrogen steel. A continuous and dense Cu3Ti3O reaction layer formed on the ceramic side, while TiN compounds were generated on the high nitrogen steel side. The maximum shear strength of the joint reached 53.74 MPa, with fracture occurring in the ceramic near the brazed seam. Excessively high or low temperatures led to discontinuous or fragmented reaction layers, thereby reducing joint strength. The Ag and Cu solid solutions exhibited good plasticity, which helped alleviate residual stress, while the thickness and continuity of the Cu3Ti3O reaction layer played a key role in the interfacial stress state and joint performance. This study provides a reliable brazing process solution for the heterogeneous joining of high-nitrogen steel and alumina ceramic.

• Research on Hot Working Process of φ1500mm Class GH4738 Alloy Turbine Disk Forged Parts

  wang zhao hui, zhang shaohui, sun panhe, yao kaijun, deng hao, xiang biao, xie jing, xu wenli, jiang he, dong jian xin

  Available online:July 13, 2026  DOI: 10.12442/j.issn.1002-185X.20260080

  Abstract(111) PDF(3.61 M)(116)

  Abstract:The ultra-large-scale GH4738 superalloy turbine disk forging for power equipment, with a diameter exceeding φ1500 mm, represents the largest GH4738 alloy forging domestically. Using the Simufact numerical simulation software, the effects of process parameters such as friction coefficient, pressing speed, and initial forging temperature on the forming load and microstructure distribution of the forging were analyzed, and the optimal forging process parameters for the φ1500 mm-scale GH4738 alloy turbine disk were determined. Subsequently, numerical simulation and trial production of a scaled-down component were conducted using the same process parameters, and the actual microstructure distribution was found to be consistent with the simulation results. Based on the validated results, die forging of the φ1500 mm-scale GH4738 alloy turbine disk was successfully carried out on an 80,000-ton die forging press. After heat treatment, the microstructure and mechanical properties of the forging met the service requirements, achieving the engineering fabrication of the φ1500 mm-scale GH4738 alloy turbine disk forging. Furthermore, the precipitate phase content at different positions of the forging was quantitatively characterized using TEM. It was revealed that during the quenching process of the ultra-large-scale forging, the non-uniform solid-solution cooling rate at different cross-sectional positions—attributed to the size effect—resulted in a significantly higher content of secondary γ" precipitates on the surface than at the core after subsequent aging, leading to notable differences in tensile properties across different positions.

• Grain growth and defect control strategy of large module single crystal superalloy turbine blades

  Mu Hao, Meng Xiangbin, Liu Jide, Zhang Chaowei, Zou Mingke, Wang Liang, Wang Meng, Fan Dahua, Ma Yuejiao, Chu Zhaokuang, Meng Jie, Liang Jingjing, Zhao Yunsong, Liu Chenguang, Zhou Yizhou, Li Qiang, Wang Ruichun, Zhu Chongwei, Li Jinguo

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250559

  Abstract(171) PDF(3.40 M)(148)

  Abstract:With the promotion and application of new large-sized single crystal superalloy turbine blades with complex air-cooled structures in aviation engines, the demand for single crystal turbine blades has sharply increased, leading to the prominent problem of cost reduction and efficiency improvement of single crystal turbine blades. At present, the growth and defect control technology of large module single crystal superalloy blades is one of the effective ways to reduce costs and increase efficiently of single crystal blades, and it is also an important development direction for the production technology of new single crystal turbine blades. Therefore, combining numerical simulation and experimental verification, the directional solidification process of single crystal superalloy turbine blades with different size modules will be studied to explore the behavior of single crystal growth, the formation law of stray grain, and corresponding control methods. The results show that during the directional solidification process, the liquid isotherm presents an "upward convex" shape, which leads to the inner side of the platform reaching the nucleation condition first, inducing the formation of stray grains in the platform. As the withdrawal rate and module size increase, the degree of "upward convex" of the liquid isotherm will significantly intensify, leading to an increased probability of stray grain formation. By adding graphite regenerator at the center of the module, the uniformity of the temperature field can be effectively improved and the inclination degree of the isotherm can be decreased, which can significantly reduce the probability of stray grain formation and improve blade qualification rate, thereby the problem of cost reduction and efficiency improvement for single crystal blades can be solved.

• Study on the Tensile Creep Behavior of Swaged W-Y?O? Alloy at High Temperatures of 1400–1600°C

  Tu cheng ming, Wang jian bao, Feng fan, Zhao dong, Wang zi jie, Jin yu zhong, Lian you yun, Liu xiang

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250572

  Abstract(132) PDF(3.00 M)(143)

  Abstract:The tensile creep behavior of Y?O?-dispersion-strengthened tungsten (W-Y?O?) alloys prepared via powder metallurgy and high-temperature rotary swaging was investigated at temperatures ranging from 1400 to 1600°C under pressures of 150 to 180 MPa. Changes in grain structure, second-phase particles, and dislocations before and after creep were analyzed using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM).Experimental results indicate that the creep performance of rotary-forged W-Y?O? alloys surpasses that of rolled pure tungsten, with a steady-state creep rate ranging from 8.22×10e-7 to 1.76×10e-4—two orders of magnitude lower than rolled pure tungsten. The superior creep performance of rotary-forged W-Y?O? primarily stems from the pinning of grain boundaries and dislocation motion by nanoscale and submicron-sized Y?O? particles, coupled with the suppression of diffusion creep due to thelarger grain aspect ratio.As temperature and creep stress increase, the agglomeration pinning effect of second-phase particles weakens, reducing the grain aspect ratio. The proportion of creep mechanisms dominated by grain boundary slip due to atomic diffusion and recrystallization gradually increases. However, dislocation motion control remains the primary mechanism in the W-Y?O? matri

• Differences in Recrystallization Behavior between the Surface and Center Layers of Hot-Rolled Thick Plate of 5xxx Aluminum Alloy

  Fang Zhijie, Wang Yujing, Mo Man, Mei Lin, Xu Lei, Xiao Zhengbing

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250573

  Abstract(159) PDF(2.97 M)(141)

  Abstract:A 5xxx series aluminum alloy hot-rolled thick plate with a final rolling temperature of 300?°C was used to systematically investigate the effects of different annealing processes (300–500?°C, 0.5–8?h) on its microstructure, mechanical properties, and electrical conductivity. The results show that increasing the annealing temperature significantly promotes recrystallization in the surface layer, while recrystallization in the center proceeds more slowly. Due to the high dislocation density and sufficient dynamic recovery introduced during hot rolling, continuous recrystallization via subgrain coalescence and growth dominates in the surface layer during annealing. In contrast, discontinuous recrystallization prevails in the center owing to its lower stored energy and fewer nucleation sites. After annealing at 450?°C for 2?h, the recrystallization fraction reaches 66.6?% at the surface but only 18.9?% in the center. With increasing annealing temperature, hardness and strength decrease, while elongation and electrical conductivity increase. Holding time has a relatively minor influence on mechanical properties, and 2?h is identified as the optimal duration. This study clarifies the mechanism underlying the difference in recrystallization behavior between the surface and center of hot-rolled thick plates during annealing, providing a theoretical basis for optimizing annealing processes.

• Influence of Heat Treatment on the Microstructural Evolution and High-Temperature Mechanical Behavior of TiAl-4822 Alloy Produced by Electron Beam Powder Bed Fusion

  Zhang Xuezhe, Wang Yifan, Zheng Hao, Niu Jingzhe, Liu Haiyan, Jia Liang, Liu Nan, Yuan Xinbo

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250578

  Abstract(156) PDF(9.68 M)(187)

  Abstract:To investigate the influence of heat treatment–induced microstructural evolution on the high-temperature mechanical behavior of Ti–48Al–2Cr–2Nb (TiAl-4822, at.%) alloy at 750 °C, specimens were fabricated via electron beam powder bed fusion (EB-PBF) and subsequently subjected to various heat treatment conditions to obtain distinct microstructures. The as-fabricated sample exhibited a heterogeneous bimodal structure composed of coarse γ bands and fine-grained duplex regions. After heat treatment at 1330 °C for 0.5 h followed by furnace cooling (FC), the alloy developed a homogeneous duplex microstructure with slightly coarsened grains. Increasing the heat treatment temperature to 1380 °C resulted in pronounced grain growth and the formation of a fully lamellar structure. With rising temperature, α? phases tended to segregate along interlamellar or intergranular regions, establishing the typical Blackburn orientation relationship with the γ phase. Mechanical testing revealed that hardness increased with heat treatment temperature, whereas both tensile strength and ductility at 750 °C decreased compared with the as-fabricated condition. The as- fabricated sample demonstrated superior high-temperature mechanical performance, achieving a tensile strength of 654.67 ± 17.01 MPa and an elongation of 42.5 ± 2.29%, primarily due to the fine γ grains and dense intragranular lamellae formed during rapid solidification. During heat treatment, the α? and γ phases coarsened through orientation-dependent growth to minimize interfacial energy, leading to lamellar thickening. The resulting coarsened lamellae and α? phase enrichment at grain boundaries and interlamellar interfaces served as preferential sites for crack initiation and propagation, thereby reducing ductility. This study elucidates the intrinsic correlations among heat treatment, microstructure, and mechanical behavior in EB-PBF TiAl-4822 alloy, providing valuable insights into tailoring the microstructure and optimizing the high-temperature performance of γ-TiAl alloys through thermal processing

• Study on the high-temperature creep behavior of single-crystal molybdenum alloys

  He Zijian, Yu Bintao, Dou Yankun, He XinFu, Zhang Lin

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250582

  Abstract(153) PDF(2.23 M)(142)

  Abstract:New reactor materials serve for a long time Under extreme loads and high temperatures. Creep resistance is the key service performance. In this paper, thermal creep experiments with different stresses (170-245MPa) were carried out at 1100K for the candidate material single crystal Mo-14Re alloy for advanced reactors. The creep time of the single crystal Mo-14Re alloy was obtained from 10 h to 780 h, and it was found that the creep of the single crystal Mo-14Re alloy conformed to the standard creep law, and the stress index n was 11.7. The creep mechanism is dislocation reinforcement, and with the increase of creep time, dislocation will form three dislocation derived structures: dislocation wall (substructure), dislocation network and dislocation cell. The above research provides a scientific basis for the research and development and safe service of advanced reactor materials.

• Anisotropy of Extrusion Texture and Adiabatic Shear Sensitivity of TC4 Alloy Bar

  Weikang Fu, Tianyuan Gong, Yi Li, Chenxing Zheng, Xinlong Dong

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250586

  Abstract(156) PDF(3.18 M)(150)

  Abstract:The microstructural orientation and texture developed during titanium alloy processing have significant effects on its dynamic mechanical behavior, particularly on adiabatic shear characteristics. In this study, the compression anisotropy and adiabatic shear behavior of the α+β TC4 alloy bar were investigated under high strain rates along the extrusion direction (ED) and transverse direction (TD) using a Split Hopkinson Pressure Bar (SHPB) apparatus. The localized deformation evolution and mechanisms were analyzed through Digital Image Correlation (DIC) and Electron Backscatter Diffraction (EBSD) techniques. The results reveal that the α-hcp phase in the extruded TC4 bar exhibits an axially symmetric cylindrical fiber texture. The yield strength in the TD is significantly higher than that in the ED; however, the TD shows greater adiabatic shear sensitivity and a higher tendency for adiabatic shear band (ASB) formation. EBSD analysis indicates that the specific crystallographic orientations induced by the extrusion texture influence yielding behavior by affecting the Schmid factors of dislocation slip systems, thereby leading to deformation anisotropy. The extrusion texture along the ED aligns most grains favorably for the activation of the basal slip system in the α-hcp phase, which has a lower critical resolved shear stress (CRSS), resulting in a lower dynamic yield strength compared with the TD. Meanwhile, the more homogeneous deformation among grains and the weaker thermal effect along the ED contribute to its lower adiabatic shear sensitivity. These findings provide insights into the influence of microstructural orientation and texture on adiabatic shear behavior in titanium alloys, offering guidance for texture control and design strategies to enhance resistance to adiabatic shear failure.

• Progress in neutron studies on the magnetic structures of rare earth magnetic materials

  LIU Dan, Ren Jianyu, Chen Weiqiang, Zheng Yusha, QIXING, XI Jianfeng

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250592

  Abstract(177) PDF(3.30 M)(143)

  Abstract:Rare-earth magnetic materials hold an indispensable strategic position in high-tech fields such as permanent magnets and magnetic refrigeration, owing to the unique characteristics of their 4f electrons: strong spin-orbit coupling, high atomic magnetic moments, and rich electronic energy levels. The multifaceted competitive mechanisms among electron exchange interactions, magnetic multipolar interactions, and crystal field effects in these materials present fundamental challenges to elucidating magnetic phase transition mechanisms and quantum excitation behaviors. Neutron scattering technology, distinguished by its sensitivity to magnetic moments, exceptional penetration capability, and ability to distinguish light elements, serves as a pivotal technique for revealing the microscopic mechanisms of magnetic structures in rare-earth systems. This technique has achieved breakthrough progress in areas including coercivity optimization of rare-earth permanent magnets and regulation of the magnetic entropy change in magnetocaloric materials. This article systematically reviews the fundamental principles and methodologies of neutron scattering technology alongside its cutting-edge applications in investigating magnetic structures within rare-earth magnetic materials, including rare-earth-transition-metal compounds, rare-earth frustrated magnets, and rare-earth low-dimensional magnets. The review aims to provide a foundational reference for advancing research on magnetic structures in rare-earth systems.

• Corrosion behavior of a Zr-xSn-0.35Fe-0.15Cr alloy in high-temperature,high-pressure oxygenated water

  zhaoduo, xiaoxiangyi, xushitong, yaomeiyi, hulijuan, xieyaoping, zhangpeng, heguanze, zhoubangxin

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250599

  Abstract(136) PDF(4.18 M)(162)

  Abstract:Zirconium alloys are extensively utilized as cladding materials for fuel elements in water-cooled nuclear reactors due to their low thermal neutron absorption cross-section, high thermal conductivity, excellent corrosion resistance, and good compatibility with UO2. Small Modular Reactors (SMRs) represent a significant direction for future nuclear energy. However, the simplified design of small water-cooled reactors, which often lack hydrogen addition and oxygen removal facilities or have limited deoxygenation capacity, leads to an elevated concentration of Dissolved Oxygen (DO) in the primary circuit coolant. This increased DO level can adversely affect the corrosion resistance of zirconium alloy cladding. Sn is an important alloying element for zirconium. Nevertheless, research on the influence of DO on the corrosion resistance of zirconium alloys with varying Sn content is scarce. Therefore, this study investigates the corrosion behavior of zirconium alloys with different Sn contents in water at 360 °C/18.6 MPa with different DO concentrations, aiming to provide a theoretical basis and guidance for developing zirconium alloy cladding materials for water-cooled SMRs. To explore the effect of Sn content on the corrosion behavior of zirconium alloys in oxygen-enriched water, corrosion tests were conducted on three Zr-xSn-0.35Fe-0.15Cr (x=0.5, 1.0, 1.5, wt%) alloys and a Zr-4 alloy in a dynamic autoclave at 360 °C/18.6 MPa with a DO concentration of 1000 μL/L. The microstructure and phase composition of the alloys and their oxide films were characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Raman spectroscopy. The results indicate that the second-phase particles (SPPs) in the Zr-xSn-0.35Fe-0.15Cr alloys are primarily composed of two types: fcc-Zr(Fe,Cr)2 and hcp-Zr(Fe,Cr)2. With increasing Sn content, the size and the Fe/Cr atomic ratio of the SPPs increase, while their area fraction decreases. During the 290-day corrosion period, the corrosion kinetics transitioned from a cubic rate law to a parabolic or power-law rate law. An increase in Sn content led to an earlier transition time in the corrosion kinetics and a higher post-transition corrosion rate. The corrosion kinetics shifted from parabolic to power-law behavior, indicating a degradation in corrosion resistance. However, all the Zr-xSn-0.35Fe-0.15Cr alloys exhibited significantly superior corrosion resistance compared to the Zr-4 alloy in the 1000 μL/L DO water environment. This paper discusses the underlying mechanism of how Sn content influences the corrosion behavior in oxygen-enriched water from the perspectives of SPPs oxidation and the microstructural evolution of the oxide film.

• A Review and Future Perspectives of Wire Arc Additively Manufactured Titanium Matrix Composites

  Lu Jinglin, Chen Zixuan, Xue Aitang, Zhang Quanli, Meng Zhibin, Zhang Xiaoyong

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250619

  Abstract(113) PDF(4.78 M)(159)

  Abstract:Titanium matrix composites (TMCs) have emerged as promising candidates for lightweight, high-strength structural components. Their appeal lies in the potential to surpass the performance limits of conventional homogeneous alloys through strategic design of reinforcements in terms of their type, morphology, and spatial distribution. Concurrently, wire arc additive manufacturing (WAAM) offers a novel paradigm for fabricating complex TMC structures with high material utilization and shortened processing routes, leveraging its dual advantages of near-net shaping and rapid solidification. This review systematically summarizes the current state of research on wire arc additively manufactured TMCs, with a focused discussion on three critical aspects: geometrical integrity, microstructural characteristics, and mechanical properties. The analysis indicates that by optimizing process parameters such as heat input and current mode, and employing auxiliary processes including preheating and maintaining temperature. can effectively mitigate defects such as porosity and cracking, thereby improving dimensional accuracy. The inherent rapid solidification of WAAM, combined with the introduction of reinforcing phases, facilitates grain refinement and enables microstructural control. Furthermore, the strategic design of architectural features such as laminated or network-like structures can lead to significant enhancement in material strength. Future research should focus on a deeper integration of process-microstructure-property relationships to accelerate the broad adoption of this technology in the manufacturing of high-performance components.

• Integrated Analysis of As-Cast Microstructural Characteristics and the Homogenization Treatment for GH3536 Superalloy

  Liu Yue, Jiang He, Yao Zhihao, Dong jianxin

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250621

  Abstract(118) PDF(5.45 M)(149)

  Abstract:In this study, the as-cast microstructure of a GH3536 electroslag ingot, produced via a vacuum induction melting plus electroslag remelting duplex process, was systematically examined using multiple characterization techniques. These included optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), extracted phase analysis, X-ray diffraction (XRD), and thermodynamic calculations. Furthermore, the microstructural evolution following homogenization heat treatment and the results of hot compression simulations were analyzed to identify an appropriate homogenization process for the alloy. The results demonstrate that molybdenum (Mo) is the primary segregating element in the alloy. In addition to the austenitic matrix, the electroslag ingot contains two types of carbides: M??C?, enriched with chromium (Cr), and M?C, enriched with Mo. After homogenization heat treatment at 1180?°C for 48?h, the coarse secondary phases were largely dissolved, and elemental segregation was significantly reduced. Consequently, the homogenized alloy exhibited excellent hot workability.

• Temperature-Dependent Modeling of High-Temperature Fatigue Crack Growth Behavior in GH4710 Superalloy

  Chen Youhong, Lan Bo, Sun Xing, Li Kai

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250623

  Abstract(122) PDF(4.10 M)(146)

  Abstract:Aiming at the high-temperature fatigue failure risk of GH4710 alloy turbine disks for aero-engines, the fatigue crack growth behavior of the alloy at 750℃, 815℃ and 850℃ was systematically studied, the temperature influence mechanism was revealed, and a temperature-dependent model was established. The results show that grain boundary oxidation weakening is the dominant factor for accelerated crack growth at high temperatures. When the temperature increases from 750℃ to 850℃, the fatigue crack growth rate of the alloy increases significantly, the fatigue life decreases by 74.7%, and the fracture mechanism transforms from transgranular dominance to intergranular dominance. The range of 815~850 ℃ is the critical mutation temperature range for fatigue performance, and below this temperature, the alloy has a wider stress intensity factor range ( ΔK) and better crack growth resistance. Based on the Paris equation, an Arrhenius-type temperature correction term was introduced to establish the model: da/dN=9.783×10^(-7)×exp?(-3557.068/T) (ΔK)^3.183 (T is absolute temperature, K). Within the range of ΔK =20~65 MPa·m?·?, the error between the model predictions and experimental data is less than 10%, which can accurately characterize the fatigue crack growth behavior of the alloy in the temperature range of 750~850℃. This study provides theoretical support for the damage tolerance design, high-temperature service life prediction and critical temperature early warning of GH4710 alloy turbine disks.

• Novel Cobalt-Based Superalloys: Compositional Design, Microstructure-Property, and Application Progress

  Wang Xiao, Luo Guoqiang, Wei Qinqin, Dai Xiangping, Shen Qiang

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250629

  Abstract(117) PDF(2.79 M)(131)

  Abstract:Conventional cobalt-based superalloys are limited in high-temperature properties due to the lack of coherent strengthening phases. The discovery of the L12-structured γ′-Co3(Al, W) phase has initiated the research on novel cobalt-based superalloys. This paper systematically reviews the recent progress in this field, covering composition design, processing techniques, microstructure, mechanical properties, and application status. The compositional strategies, including multi-component alloying and density reduction, are elaborated. Combined with typical cases, the breakthroughs of additive manufacturing technology in suppressing segregation and cracking are discussed. Furthermore, strengthening models are introduced to quantitatively analyze the influence of γ′ phase characteristic parameters on strength. In addition, the key mechanisms for improving high-temperature oxidation and hot corrosion resistance are deeply discussed. Finally, the application progress of these alloys in aero-engine hot-end components and high-temperature tools and molds is summarized, and future development directions regarding microstructural stability and engineering fabrication are proposed.

• Research Progress on Laser-cladded High-Entropy Alloy Coatings

  Wang Ruixin, Zhang Yong, Zhang Yitian, Liu Jiahui, Ma Lei, Han Xiaoliang, Wang Hui, Song Kaikai

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250639

  Abstract(141) PDF(1.94 M)(134)

  Abstract:High-entropy alloys demonstrate outstanding comprehensive performance due to their revolutionary multi-component design concept, making them ideal materials for achieving structural-function integration. The laser cladded high-entropy alloy coatings combines the performance advantages of high-entropy alloys with the technical advantages of laser cladding, achieving a high-quality balance among surface performance, mechanical performance, and functional performance, and showing great potential for engineering applications. This paper starts from the "process-microstructure-performance" relationship and the intrinsic mechanism. The preparation methods and optimization strategies are summarized. The microstructure, performance and performance improvement mechanisms under single and coupled conditions are revealed. The potential application scenarios and the problems that need to be solved urgently in current applications and the future development direction are disccused.

• Elevated shear strength of aged Sn58Bi solder joints under low density current stressing

  Gong Zhiwen, Li Wangyun, Lin Yichun, Hu Fei, Cai Huihong, Yue Wu

  Available online:June 01, 2026  DOI: 10.12442/j.issn.1002-185X.20250644

  Abstract(122) PDF(9.37 M)(169)

  Abstract:This study investigates the impact of low density current stressing on the shear performance of thermally aged Sn58Bi solder joints and elucidates the underlying mechanisms. Cu/Sn58Bi/Cu joints were subjected to isothermal aging at 120 °C for different durations (0 h, 240 h, 480 h, 720 h, 960 h, 1200 h, 1440 h, 1680 h) and tested under current densities of 0, 1×103, 2×103, and 3×103 A/cm2. The results indicate a non-monotonic "rise-fall" trend in the shear strength of aged joints with increasing current density. Notably, a maximum strength increase of 12.85 % was observed in joint aged for 480 h under a current density of 2×103 A/cm2, comparing with the unaged and current-free ones. This strengthening behavior at 480 h is primarily attributed to two mechanisms: (1) the applied current promotes the multiplication of geometrically necessary dislocations (GNDs), elevating strength via dislocation strengthening; and (2) higher current density facilitates an increase in the subgrain fraction of the Bi phase, which effectively impedes dislocation motion. Conversely, at higher current densities, shear strength decreases due to Joule heating, which induces thermal mismatch and compromises the interfacial bonding between the interfacial intermetallic compounds (IMC) layer and the solder matrix. These findings provide theoretical insights for the reliability assessment of low-temperature solder joints in electronic packaging.

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