2025,Volume 54, Issue 2

>2025 Heterogeneous and complex structural connections

• Phase Formation Mechanism of Al-Si-Ge Filler Metals Based on Thermodynamics Calculation

  Huang Sen, Long Weimin, Shan Jiguo, Jiang Chao, Jing Peiyao, Zhang Guanxing

  2025,54(2):293-300 DOI: 10.12442/j.issn.1002-185X.20240431

  Abstract(14) HTML(68) PDF(3.79 M)( 54)

  Abstract:A series of Al-xSi-yGe filler metals (x=4–12 and y=10–40, wt%) were prepared, and the effect of Si and Ge on microstructure and melting characteristics of filler metals was studied. The thermodynamic model of Al-Si-Ge ternary alloy was established to analyze the phase formation mechanism of filler metals based on Miedema model, Tanaka model, and Toop equation. This research provided a basis for the composition optimization of filler metals and the analysis of metallurgical reaction process between filler metals and base materials. Results show that Al-Si-Ge alloy is composed of Al-Ge eutectic phase, Al-Si eutectic phase, and primary Si. Ge addition promotes the precipitation of primary Si. Ge is the main melting point depressant element of filler metals. With the increase in Ge content from 10wt% to 40wt%, the solid phase line of filler metals remains unchanged, whereas the liquidus temperature decreases from 567.65 °C to 499.96 °C. With the increase in Ge content of filler metal, Ge content in eutectic Si phase is increased, the endothermic peak of Al-Si eutectic reaction according to thermogravimetry curve becomes smoother, and Al-Si eutectic temperature is decreased. Ge addition can reduce the free energy of Al-Si alloy system. The lowest point of free energy is located on Al-Ge side. The eutectic Ge phase with the composition similar to pure Ge composition is the most likely to appear in the microstructure of filler metals, whereas the eutectic Si phase with the composition similar to pure Si composition is the least likely to appear. The thermodynamic calculation results are consistent with the experiment results.

• Interfacial Structure and Mechanical Properties of Dia-mond/Copper Joint Brazed by Ag-Cu-In-Ti Low-Temperature Brazing Filler

  Pan Yufan, Liang Jiabin, Nie Jialong, Liu Xin, Sun Huawei, Chang Yunfeng, Li Huaxin, Lu Chuanyang, Xu Dong, Wang Xingxing, Yang Yang, Yang Jianguo, He Yanming

  2025,54(2):301-310 DOI: 10.12442/j.issn.1002-185X.20240655

  Abstract(14) HTML(47) PDF(2.98 M)( 28)

  Abstract:Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper, and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were investigated. In addition, the joint formation mechanism was discussed, and the correlation between joint microstructure and mechanical performance was established. Results show that adding appropriate amount of In into the filler can significantly reduce the filler melting point and enhance the wettability of filler on diamond. When the brazing temperature is 750 °C and the soaking time is 10 min, a uniformly dense braze seam with excellent metallurgical bonding can be obtained, and its average joint shear strength reaches 322 MPa. The lower brazing temperature can mitigate the risk of diamond graphitization and also reduce the residual stresses during joining.

• Dissimilar Friction Stir Lap Welding of Ti Alloy and Al-Li Alloy: Microstructure and Mechanical Property

  Zhang Wenxin, Zhang Xiankun, Shi Lei, Li Shengli, Jiang Yuanning, Wu Chuansong

  2025,54(2):311-318 DOI: 10.12442/j.issn.1002-185X.20240605

  Abstract(8) HTML(38) PDF(2.87 M)( 22)

  Abstract:Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation, microstructure, and mechanical properties of the joints. Results show that under different welding parameters, with the decrease in welding heat input, the weld surface is smoother. The Ti/Al joint interface is flat without obvious Ti and Al mixed structure, and the hook structure is not formed under optimal parameters. Due to the enhanced breaking effect of the stirring head, the hook structural defects and intermetallic compounds are more likely to form at the Ti/Al interface at high rotational speed of 1000 r/min, thereby deteriorating the mechanical properties of joints. Decreasing the heat input is beneficial to hardness enhancement of the aluminum alloy in the weld nugget zone. Under the optimal parameters of rotation speed of 800 r/min and welding speed of 120 mm/min, the maximum tensile shear strength of joint is 289 N/mm.

• Preparation and Performance of Large-Size Seamless Zirconium-Titanium-Steel Composite Plate

  Wu Jiangtao, Wang Ding, Huang Xingli, Zou Juntao, Zhang Penghui, Gao Ruibo, Yang Huan, Zhang Tao, Ren Qianyu, Wei Yong

  2025,54(2):319-326 DOI: 10.12442/j.issn.1002-185X.20240438

  Abstract(36) HTML(44) PDF(1.29 M)( 22)

  Abstract:Zirconium-titanium-steel composite plate with the size of 2500 mm×7800 mm×(3+0.7+22) mm was prepared by explosive welding+rolling method, and its properties were analyzed by ultrasonic nondestructive testing, phased array waveform shape, interface structure shape, electronic scanning, and mechanical property testing. Results show that the rolling temperature of zirconium-titanium complex should be controlled at 760 °C, and the rolling reduction of each pass should be controlled at 10%–25%. The explosive velocity to prepare zirconium-titanium-steel composite plates should be controlled at 2450–2500 m/s, the density should be 0.78 g/cm³, the stand-off height should be 12 mm, and the explosive height of Zone A and Zone B should be 45–50 mm. Explosive welding combined with rolling method reduces the impact of explosive welding and multiple heat treatment on material properties. Meanwhile, the problems of surface wrinkling and cracking, which occur during the preparation process of large-sized zirconium-titanium-steel composite plate, can be solved.

• Research Status of Short Process Forming Techniques for Brazing and Soldering Materials

  Dong Bowen, Shi Guangyuan, Zhong Sujuan, Dong Xian, Cheng Yafang, Long Weimin, Zhang Guanxing

  2025,54(2):377-384 DOI: 10.12442/j.issn.1002-185X.20240428

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  Abstract:Short process forming techniques for brazing and soldering materials can shorten the process, improve product quality, and increase production efficiency, which has received much attention from welding researchers. This review mainly summarized the research reports on short process forming techniques for brazing and soldering materials. Firstly, the traditional process and its shortcomings were presented. Secondly, the latest research of short process forming technologies, such as continuous casting technique, atomization powder technique, solder ball forming technique, and rapid solidification technique, was summarized, and the traditional forming performance of several brazing and soldering materials was introduced. Finally, the current restrictions and research trends of short process forming technique for brazing and solder materials were put forward, providing theoretical guidance and reference for related research and technique development in brazing and soldering field.

• Interfacial Microstructure and Mechanical Properties of Zr/CoCrFeMnNi HEA Brazed Joints

  Du Peng, Song Xiaoguo, Long Weimin, Bian Hong, Qin Jian, Sun Huawei, Jiang Nan

  2025,54(2):385-393 DOI: 10.12442/j.issn.1002-185X.20240591

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  Abstract:AgCu filler was used to braze Zr and CoCrFeMnNi high-entropy alloy (HEA). The effects of brazing temperature and holding time on the microstructure and mechanical properties of the joints were analyzed. The results show that the typical microstructure of the joints brazed at 850 ℃ for 10 min is HEA/Cr_ss/Zr(Cr,Mn)₂/Zr₂(Co,Cu,Ni,Fe)+Zr₂(Ag,Cu)+Zr(Cr,Mn)₂/Zr. The joints have the maximum shear strength of 103.1 MPa. As the brazing temperature or holding time rises, the thickness of Cr-rich solid solution and Zr(Cr,Mn)₂ layer are increased, the content of Zr₂(Co,Cu,Ni,Fe) and Zr(Cr,Mn)₂ phase is increased whereas the content of Zr₂(Ag,Cu) phase is decreased. Finally, the failure mechanism of the joint was analyzed. Under the action of shear force, as the brazing temperature or holding time rises, the fracture position of the joint shifts from the Zr(Cr, Mn)₂ layer to the Zr₂(Co, Cu, Ni, Fe) phase fracture in the center of the brazing seam.

• Microstructure and Mechanical Properties of Vacuum Brazed TA1 Joints with TiZrCuNi Filler Metal

  Liu Dashuang, Li Xionghui, Xu Jianhua, Lu Sheng, Fang Naiwen, Zhang Yuke, Shen Yuanxun, Zhong Sujuan, Long Weiming

  2025,54(2):394-400 DOI: 10.12442/j.issn.1002-185X.20240365

  Abstract(5) HTML(36) PDF(12.56 M)( 18)

  Abstract:Ti-10Zr-10Cu-10Ni powder was used as a brazing filler for vacuum brazing of commercial pure titanium TA1 at 880 ℃ for 30 min and 910 ℃ for 30 min. Following this, interface microstructure and performance analyses were carried out on two sets of distinct brazed joints. The results show that the microstructure of the two sets of joints is made up of TA1+acicular α-Ti+eutectoid (α-Ti+(Ti, Zr)₂(Cu, Ni)+ residual filler/TAl. The Zr elements are scattered in the eutectoid structure, residual filler and acicular α-Ti, while the Cu and Ni elements are mostly distributed in the eutectoid structure and residual filler. The mechanical properties of the two types of brazed joints differ significantly. When exposed to of brazed joint, the tensile strength of brazed joint at room temperature is around 174 MPa. The room temperature tensile strength rises to around 491 MPa when it is subjected to 910 ℃. The hardness of the material exhibits a progressive rise from the base material to the welding center. At 910 ℃, the greatest recorded hardness (HV) is around 2842 MPa, while at 880 °C, the maximum hardness (HV) reaches 3724 MPa. The mechanical difference between the two joints is mostly caused by the separation of Zr element, which create a brittle, layered intermetallic compound. Fracture analysis of the specimens reveals that the cracks in both sets of interfaces propagate along the weld seams. The fracture surface at 880 ℃ exhibits cleavage fracture characteristics, while at 910 ℃ it demonstrates a ductile fracture mode.

• Microstructure， Properties and Stress Analysis of Thick-Walled Titanium Alloy Laser Welded Joint with Filler Welding Wire

  Wu Pengbo, Feng Zhiqiang, Fang Naiwen, Lu Quanbin, Huang Ruisheng, Liao Zhiqian, Sun Laibo, Qin Jian, Li Quan, Chang Yunfeng, Shanyu Niudong

  2025,54(2):401-412 DOI: 10.12442/j.issn.1002-185X.20240660

  Abstract(6) HTML(31) PDF(17.43 M)( 25)

  Abstract:To realize high quality and high efficiency welding of large thickness titanium alloy, a flux-cored welding wire was developed by optimizing the synergistic mechanism of metal powder cores. The microstructure evolution of the interlayer region of the welded joint was studied, the stress distribution in the process of laser welding was analyzed by numerical simulation, and the ultra-narrow gap laser welding of TC4 titanium alloy plate with 96 mm in thickness was realized. The results show that the average tensile strength of the upper, middle and lower parts of the welded joint is 935 MPa, the average yield strength is 794 MPa, and the elongation is 20%. The average value of the impact toughness of the upper, middle and lower welded joints at room temperature is 31 J, and the microstructure and properties of the welded joints are well distributed along the wall thickness direction. With the pass of welding increasing, the change from compressive stress to tensile stress occurs in the welded seam center; the high stress zone of transversal and longitudinal residual stress is not in the surface of the sample, but in the welded seam with 6 mm to the surface, and the maximum tensile stress is 1030 MPa.

• Microstructure and Properties of Transient Liquid Phase Bonding Joints of DD5 Single Crystal Alloy

  Wei Li, Yao Jian, Zhang Jianting, Sun Haohua, Li Yanqing, Xiao Lei

  2025,54(2):413-420 DOI: 10.12442/j.issn.1002-185X.20230798

  Abstract(4) HTML(23) PDF(7.97 M)( 18)

  Abstract:The transient liquid phase bonding (TLP) welding test of DD5 Ni-based single crystal superalloy was carried out under welding conditions of 1280 ℃, 12 h, 0.01 MPa using the self-developed TLP interlayer material. The microstructure and precipitates of the welded joint were analyzed using SEM and the thermodynamic software JMatPro. The results show that the thickness of the interlayer has a significant impact on the microstructure of the welded joint. When the thickness of the interlayer is 120 μm, the microstructure and composition of the weld and the base metal tend to be consistent, and no obvious brittle precipitates are formed; the γ′ phase in the weld zone and matrix are basically combined. When the thickness of the interlayer is 160 and 200 μm, the athermally solidified zone (ASZ) is composed of brittle phases such as sunflower-like eutectic structure, fishbone-like borides, and block carbides rich in Ta and Hf. After post weld heat treatment (PWHT), the γ′ square degree of weld zone is significantly improved, and the size is basically consistent with that in the substrate. The stress rupture test was conducted under the condition of 980 ℃, 248 MPa. When the thickness of the intermediate layer is 120 μm, the stress rupture life can reach 145.54 h. And the results show that as the thickness of the intermediate layer increases, the stress rupture life of the joint continues to decrease, and the fracture mode changes from ductile fracture to brittle fracture.

• Effect of Vacuum Brazing on Bonding Strength Between Metal Rubber Core and Panel

  Wei Yuhan, Ge Shaoxiang, Xue Xin

  2025,54(2):421-428 DOI: 10.12442/j.issn.1002-185X.20240381

  Abstract(5) HTML(19) PDF(6.74 M)( 15)

  Abstract:To address the unclear matching issue between the vacuum brazing process of sandwich panel with metal rubber core and its material properties, simulation and orthogonal experimental methods were employed to investigate the influence of heating rate, maximum heating temperature, and holding time on the shear performance and connection strength. In addition, the shear damage behavior of the sandwich panel was analyzed by macro and micro method. The results indicate that sandwich panel prepared by vacuum brazing process exhibits excellent shear and connection strength. During the vacuum brazing process, the temperature deviation at all selected sample points is less than 10 K. Additionally, the residual stress is primarily concentrated at the junction of the wire and the solder, and the nearer the distance to central region, the smaller the residual stress. The maximum residual stress is negatively correlated with the shear performance and joining strength of the sandwich panel. Moreover, the optimum technological parameter (1090 ℃,4 ℃/min and 20 min) of the brazing process for fabricating the sandwich panel is obtained by range analysis.

• Microstructure and Mechanical Properties of C/C-GH4169 Joint Brazed with High Entropy Alloy

  Jiang Wei, Yu Kang, Li Xinyi, Dai Jixiang, Sha Jianjun

  2025,54(2):429-436 DOI: 10.12442/j.issn.1002-185X.20240399

  Abstract(4) HTML(12) PDF(11.25 M)( 12)

  Abstract:Nb_0.74CoCrFeNi₂ high-entropy powder brazing was used to braze C/C composites and GH4169. The effects of brazing temperature and holding time on the microstructure and shear strength of the joints were investigated to reveal the formation mechanism of the joints. Results show that the typical structure of joint is Cr₂₃C₆+(Cr,Ni)₂₃C₆/(Cr,Ni)₃C₂+NbC/fcc+Ni(s,s)+NbNi₃. With the reaction progressing on the side interface of the composite, the Cr element is gradually consumed, forming a unique gradient interfacial structure, which is conducive to relieve the residual stresses of the joint. With the increase in brazing temperature or the prolongation of holding time, the internal defects of the joints gradually disappear, but the thickness of the brittle interfacial reaction layer increases sharply, and thus the joint shear strength shows a tendency of first increasing and then decreasing. When the brazing temperature is 1260 ℃ and the holding time is 25 min, the shear strength of the brazed joint is up to 139.6 MPa, and the shear strength at high temperature of 1000 ℃ is still as high as 89.7 MPa. The high shear strength originates from the diffusion and infiltration of filler into the composite material side, which forms a strong interfacial reaction bond.

• Effect of Laser Remelting on Microstructure and Properties of Diamond/Ni-Based Composite Coatings

  Wu Qilong, ZhaoHongwei, Zhang Lei, Sun Zhipeng, Li Yujia, Cheng Zhan, Yuan Shicheng

  2025,54(2):437-444 DOI: 10.12442/j.issn.1002-185X.20240408

  Abstract(2) HTML(19) PDF(6.16 M)( 9)

  Abstract:To investigate the effect of laser remelting on the microstructure and properties of diamond/Ni-based composite coatings, diamond/Ni-based composite coatings were prepared on the surface of Q235 by induction heating. The macroscopic morphology, microstructure, elemental distribution and mechanical properties of the coatings before and after laser remelting were analyzed by ultra-deep field microscope, laser confocal microscope, scanning electron microscope, energy spectrometer, X-ray diffractometer, hardness tester and abrasive wear tester. The results show that after laser remelting, the number of exposed diamonds on the surface decreases and the average roughness of the surface of the composite coating decreases from 5.58 μm to 4.88 μm. The number of hole defects in the microstructure is significantly reduced, and the carbide in the microstructure aggregates and grows up, while the enrichment degree of Cr element increases around the diamond; there is no significant change in the microhardness of the brazing alloy and the abrasion-resistant properties of the coating.

• Interface Bonding Behavior of CFRTP/Al Alloy Under the Effect of Temperature and Pressure

  Qu Hua, Song Kunlin, Zhang Lijiao, Zhu Hongbin, Wang Zhenmin

  2025,54(2):445-452 DOI: 10.12442/j.issn.1002-185X.20240589

  Abstract(14) HTML(14) PDF(14.54 M)( 14)

  Abstract:The composite structure of carbon-fiber-reinforced-thermoplastic (CFRTP) and aluminum alloy can combine the excellent properties of these materials, and has great application potential in rail transit, aerospace and other fields where lightweight needs to be considered. Welding technology has the advantages of strong stability and high sealing, which is a new technology to explore the preparation of CFRTP and aluminum alloy composite structures. However, due to the large differences in physical and chemical properties of dissimilar materials, the welding joint has low compatibility and poor weldability, and the current welding process conditions are not clear about the bonding mechanism of the welded joint. Therefore, the molecular dynamics (MD) simulation method was adopted in this study, and polyamide 66 (PA66) was used as the matrix material of carbon fiber-reinforced PA66 (CFRPA66). The motion and interaction mechanism of PA66 and Al atoms under different temperatures and pressures during welding were studied. The results show that the changes of temperature and pressure during the welding process exert significant effects on the atomic diffusion and bonding behavior at the interface between PA66 and Al. When the reaction time is 10 ps, the absolute value of the interaction energy reaches the maximum value at 550 K or 1.5 MPa. The simulation results provide a theoretical basis for the optimization of welding process parameters between CFRPA66 and Al alloy, and lay a solid foundation for the industrial application of CFRTP/Al alloy composite joints.

• On Low-Temperature Brazing of AlN Ceramics and Al：Design of Brazing Material， Microstructure and Properties of Joint

  Zhou Hangze, Long Fei, Xu Rui, Wang Ce, He Peng, Shi Qingqing, Zhao Yan

  2025,54(2):453-462 DOI: 10.12442/j.issn.1002-185X.20240628

  Abstract(6) HTML(19) PDF(8.61 M)( 12)

  Abstract:This study addresses the lack of brazing materials suitable for low-temperature brazing of AlN ceramics and Al. By adding elements In and Sn to AgCuTi brazing materials to lower their melting points, new low-temperature brazing materials Ag-28Cu-35In-2Ti and Sn-19Ag-14.35Cu-17.5In-1Ti were prepared to achieve good bonding of AlN/Al joints. The low-temperature brazing process, joint microstructure and properties of AlN ceramics and Al using two types of brazing materials were explored. Results show that for Sn-19Ag-14.35Cu-17.5In-1Ti brazing materials relatively stable compounds such as InSn₃ and Al₃Ti form at the solder joints. Ag-28Cu-35In-2Ti brazing material generates relatively stable compounds such as Al₂Cu, AgIn₂, and TiAl₃ at the solder joint, and the joint strength increases with the increase in welding temperature. To prevent the diffusion and precipitation of In, Ni plating is chosen on the surface of Al, but it reduces the thermal conductivity of the joint. It is found that using Ag-28Cu-35In-2Ti brazing material for welding contributes to the highest joint strength of 20.28 MPa at 640 ℃ for 30 min; under the condition of 620 ℃ for 15 min, the thermal diffusion coefficient can reach 65.941 m²/s. This brazing material provides a new method for highly reliable connection of AlN ceramics/Al.

• Influence Mechanism of Ultrasound-Assisted Process on Microstructure of Diamond/AlSi Composite Coating

  Ding Tianran, Yang Jiao, Zhang Lei, Qin Jian, Zhu Hongtao, Jing Peiyao

  2025,54(2):463-473 DOI: 10.12442/j.issn.1002-185X.20240425

  Abstract(5) HTML(22) PDF(13.70 M)( 16)

  Abstract:Diamond/AlSi composite coatings were prepared on Ti-6Al-4V alloy matrix by ultrasound-assisted brazing coating technology. The effects of ultrasonic brazing process parameters on the microstructure of diamond/AlSi brazing coating were investigated. The interfacial reaction mechanism between AlSi filler metals and diamond on the matrix under ultrasonic action was discussed. The results show that TiAl₃ compounds and a large number of Ti(Al_1-xSi_x)₃ compounds are mainly formed in the contact interface between titanium alloy matrix and AlSi filler metals. The growth of Ti(Al_1-xSi_x)₃ is mainly affected by the interfacial reaction and the diffusion rate of atoms to the reaction site. Ultrasonic treatment can improve the wetting and spreading effect of AlSi filler metal on the matrix by cavitation effect to achieve the wetting of diamond particles by inactive AlSi brazing filler metal. The mechanism is that the intermetallic compound Ti(Al_1-xSi_x)₃ is formed at the interface between AlSi filler metals and the substrate. Ti(Al_1-xSi_x)₃ is broken and dispersed throughout the brazing coating by ultrasonic cavitation and acoustic streaming effect, ultimately leading to the reaction of Ti, an element in the titanium alloy matrix, with diamond to form TiC.

• Microstructure Evolution and Mechanical Properties of Sapphire/TC4 Alloy Joints Brazed by Ag-Cu-3Ti Filler Metal

  Liu Quanming, Xiao Junfeng, Tang Wenshu, Gao Song, Sun Huawei, Qin Jian, Chen Yafang, Zhai Chunhua, Huang Qing, Niu Chenhui

  2025,54(2):474-480 DOI: 10.12442/j.issn.1002-185X.20240402

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  Abstract:Sapphire/metal welding connection faces the challenge of poor wetting of sapphire surface by brazing materials. The interface structure of the sapphire/Ag-Cu-3Ti/TC4 alloy brazed joint, the effects of temperature and holding time on the shear properties, and the mechanism of interface connection were studied. The results show that the sapphire side forms a dense metallurgical reaction layer. The microstructure of the reaction layer is composed of Ag base solid solutions, Cu base solid solids and the crystal. TC4 alloy side forms a crispy layer and a crystal infiltration area. With the increase in brazing temperature, the shear strength of the brazed joint reduces significantly. As the holding time is prolonged, the shear strength of the brazed joint increases firstly and then decreases. The fracture surface of the brazed joint exhibits a mixed fracture morphology of the sapphire brittle fracture and filler metal “adhesive type” fracture. The brazing connection relies solely on the metallurgical bonding strength between a small portion of Ag-Cu-3Ti brazing metal and the sapphire. During the brazing process, Ti and Cu diffuse towards the sapphire side and accumulate on the surface of Al₂O₃. Sufficient solid-liquid interaction occurs at the interface to form stable intermetallic compounds, and the TC4 alloy side grains continuously grow towards the matrix, resulting in a significant increase in the shear strength of the brazed joint.

• Influence of Brazing Process on the Microstructure and Wear Resistance of Diamond Composite Coating on TC4

  Sun Huawei, Liu Pan, Zhang Lei, Qin Jian, Zhu Hongtao, Jing Peiyao

  2025,54(2):481-489 DOI: 10.12442/j.issn.1002-185X.20240426

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  Abstract:In order to improve the surface wear resistance of titanium alloys, TC4 (Ti-6Al-4V) was selected as the matrix material, and diamond particles (20%, mass fraction) and CuTi alloy powder (10%, mass fractions) were added to Al-12Si filler metal. The diamond composite wear-resistant brazing coating on TC4 surface was prepared by induction brazing under argon protection. The effects of particle size of CuTi alloy, brazing temperature, and isothermal reaction time on the microstructure and wear resistance of composite coatings were studied. The results indicate that the composite coating is mainly composed of α-Al, Ti(Al_1-xSi_x)₃, CuAl₂, and diamond particles. Reducing the particle size of CuTi alloy powder and increasing the brazing temperature can promote its full reaction with the brazing alloy. With the increase in temperature and insulation time, the CuAl₂ phase at the grain boundary between α-Al and Ti(Al_1-xSi_x)₃ gradually disperses, improving the hardness of the brazing alloy coating. However, excessive insulation can cause the CuAl₂ phase to start growing and to overlap with each other to form a coarse network structure, resulting in a significant increase in brittleness and a decrease in wear resistance of the brazed coating alloy.

• Research Progress on Welding and Additive Manufacturing of Aluminum/Steel Dissimilar Metals

  Lin Chunfa, Li Xiang, Han Yuqiang, Dong Longlong, Dai Yuxuan, Zhu Chengqi

  2025,54(2):524-532 DOI: 10.12442/j.issn.1002-185X.20240395

  Abstract(4) HTML(23) PDF(9.09 M)( 16)

  Abstract:Aluminum/steel bimetallic structures show a good application prospect in lightweight vehicle manufacturing due to the low density of aluminum alloy and the high strength and low cost of steel. Nowadays, aluminum/steel components can be prepared easily and rapidly by welding and additive manufacturing techniques. However, there are some urgent problems such as the differences in physical properties between Al and steel, the formation of continuous Fe-Al intermetallic compounds, which decrease the mechanical properties of aluminum/steel interface of the components. The weldability of aluminum/steel dissimilar metals was discussed, as well as the development status of aluminum/steel dissimilar metal welding and the regulating and eliminating methods of Fe-Al intermetallic compounds. Moreover, the latest investigations on the arc additive manufacturing and laser additive manufacturing of aluminum/steel bimetallic components were also expounded. The similarities and differences between additive manufacturing and welding of aluminum/steel components were investigated. Finally, several suggestions for further research directions of aluminum/steel dissimilar metal welding and additive manufacturing were proposed.

>Materials Science

• Effect of Hot Working on Microstructures and Mechanical Properties of Gravity-Cast Al-8.3Zn-3.3Cu-2.2Mg High-Strength Aluminum Alloy

  Qi Yushi, Jin Yu, Wei Fangming, Du Lanjun, Ren Yan, Liang Xueqian, Chen Gang, Du Zhiming

  2025,54(2):327-336 DOI: 10.12442/j.issn.1002-185X.20240353

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  Abstract:The microstructures and mechanical properties of Al-8.3Zn-3.3Cu-2.2Mg alloys prepared via hot extrusion and liquid forging methods were investigated. Results show that based on DEFORM simulation analysis, the optimal hot extrusion parameters are determined as ingot initial temperature of 380 °C and extrusion speed of 3 mm/s. The hot-extruded aluminum alloy after T6 heat treatment presents superior mechanical properties with yield strength of 519.6 MPa, ultimate tensile strength of 582.1 MPa, and elongation of 11.0%. Compared with the properties of gravity-cast and liquid-forged alloys, the yield strength of hot-extruded alloy increases by 30.8% and 4.9%, and the ultimate tensile strength improves by 43.5% and 10.2%, respectively. The significant improvement in tensile strength of the hot-extruded alloys is attributed to the elimination of casting defects and the refinement of matrix grain and eutectic phases. In addition, the hot-extruded alloy demonstrates superior plasticity compared with the liquid-forged alloy. This is because severe plastic deformation occurs during hot extrusion, which effectively breaks and disperses the eutectic phases, facilitating the dissolution and precipitation of the second phases and inhibiting the microcrack initiation.

• Relationship Between Stress and Texture in L1₀-FePt Thin Films

  Wang Xuanli, Li Wei

  2025,54(2):337-342 DOI: 10.12442/j.issn.1002-185X.20240594

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  Abstract:Impact of texture type on the magnetic properties of ultrahigh density perpendicular magnetic recording media L1₀-FePt thin film was investigated, so were the texture formation and evolution mechanism. Reuss, Voigt, and Hill models were used to determine the anisotropic elastic modulus of L1₀-FePt thin film with fiber texture. Then, the elastic strain energies of thin films under various stress conditions were calculated. Results reveal that the stress condition has a significant influence on the fiber texture evolution. When the L1₀-FePt thin film is subjected to compressive in-plane strain prior to ordering phase transformation, the formation of {100} fiber texture is promoted. On the contrary, the ordering phase transformation under tensile in-plane strain promotes the {001} fiber texture formation.

• Effect of Aluminum Content on Microstructure and Tribolo-gical Properties of CoCrFeNi₂-Based High-Entropy Alloys

  Zhang Mengdi, Zhang Gaimei, Luo Chongwei, Xu Hanqing

  2025,54(2):343-353 DOI: 10.12442/j.issn.1002-185X.20240625

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  Abstract:Four machine learning algorithms were used to predict the solid solution phases of high-entropy alloys (HEAs). To improve the model accuracy, the K-fold cross validation was adopted. Results show that the K-nearest neighbor algorithm can effectively distinguish body-centered cubic (bcc) phase, face-centered cubic (fcc) phase, and mixed (fcc+bcc) phase, and the accuracy rate is approximately 93%. Thereafter, CoCrFeNi₂Al_x (x=0, 0.1, 0.3, 1.0) HEAs were prepared and characterized by X-ray diffractometer and energy disperse spectrometer. It is found that their phases are transformed from fcc phase to fcc+bcc phase, which is consistent with the prediction results of machine learning. Furthermore, the influence of Al content on the microstructure and tribological properties of CoCrFeNi₂Al_x (x=0, 0.1, 0.3, 1.0) HEAs was evaluated. Results reveal that with the increase in Al content, the nanohardness and microhardness increase by approximately 45% and 75%, respectively. The elastic limit parameter H/E_r increases from 0.0216 to 0.030, whereas the plastic deformation resistance parameter H³/E_r² increases from 0.0014 to 0.0045, which demonstrates an improvement in nanohardness with the increase in Al addition amount. In addition, the wear rate decreases by 35% with the increase in Al addition amount. This research provides a new idea with energy-saving and time-reduction characteristics to prepare HEAs.

• Characterization and Analysis of Abnormal Grain Structures in WSTi6421 Titanium Alloy After β Annealing Treatment

  Wang Wensheng, Liu Xianghong, Wang Haipeng, Wang Kaixuan, Tian Yanwen, Yan Jianchuan, Li Yulu, Chen Haisheng

  2025,54(2):354-362 DOI: 10.12442/j.issn.1002-185X.20240016

  Abstract(7) HTML(17) PDF(5.70 M)( 12)

  Abstract:As-forged WSTi6421 titanium alloy billet after β annealing was investigated. Abnormally coarse grains larger than adjacent grains could be observed in the microstructures, forming abnormal grain structures with uneven size distribution. Through electron backscattered diffraction (EBSD), the forged microstructure at various locations of as-forged WSTi6421 titanium alloy billet was analyzed, revealing that the strength of the β phase cubic texture generated by forging significantly influences the grain size after β annealing. Heat treatment experiments were conducted within the temperature range from T_β-50 °C to T_β+10 °C to observe the macro- and micro-morphologies. Results show that the cubic texture of β phase caused by forging impacts the texture of the secondary α phase, which subsequently influences the β phase formed during the post-β annealing process. Moreover, the pinning effect of the residual primary α phase plays a crucial role in the growth of β grains during the β annealing process. EBSD analysis results suggest that the strength of β phase with cubic texture formed during forging process impacts the orientation distribution differences of β grains after β annealing. Additionally, the development of grains with large orientations within the cubic texture shows a certain degree of selectivity during β annealing, which is affected by various factors, including the pinning effect of the primary α phase, the strength of the matrix cubic texture, and the orientation relationship between β grain and matrix. Comprehensively, the stronger the texture in a certain region, the less likely the large misoriented grains suffering secondary growth, thereby aggregating the difference in microstructure and grain orientation distribution across different regions after β annealing.

• Formulation and Characterization of Functionally Graded Materials Comprising SS316L and Inconel625 for En-hanced Performance in High-Pressure Pneumatic Tools

  Sainath Krishna Mani Iyer, Karuppasamy Ramasamy, Prabagaran Subramaniam

  2025,54(2):363-376 DOI: 10.12442/j.issn.1002-185X.20240782

  Abstract(15) HTML(13) PDF(3.20 M)( 18)

  Abstract:SS316L alloy coupled with Inconel625 alloy were combined with Ti6Al4V or Inconel718 alloy through wire arc additive manufacturing technique to manufacture functionally graded materials (FGMs). Two FGMs, namely 60% SS316L+20% Inconel625+20% Ti6Al4V composite and 60% SS316L+20% Inconel625+20% Inconel718 composite, were prepared. The tensile strength, elongation, yield strength, hardness, cross section area of the parent material, and composition were analysed. Results illustrate that the 60% SS316L+20% Inconel625+20% Inconel718 composite has better mechanical properties than 60% SS316L+20% Inconel625+20% Ti6Al4V composite, and the comprehensive properties of 60% SS316L+20% Inconel 625+20% Ti6Al4V composite are better than those of the parent material SS316L. Hence, the composite of 60% SS316L+20% Inconel625+20% Inconel718 is optimal. Due to its high strength, the 60% SS316L+20% Inconel625+20% Inconel718 composite has great application potential in the field of high pressure pneumatic tool and defence tool.

• Coarsening Behavior of Bimodal γ′ Phase in K439B Cast Superalloy During Long-Term Aging

  Qu Xinghai, Gao Lei, Wu Yidong, Hui Xidong, Xiao Chengbo, Chen Jingyang

  2025,54(2):490-496 DOI: 10.12442/j.issn.1002-185X.20230721

  Abstract(8) HTML(12) PDF(9.91 M)( 8)

  Abstract:This article took K439B alloy with a temperature bearing capacity of 800 ℃ as the research object to study the γ′ phase morphology in the standard heat-treated condition, and the γ′ phase evolution and coarsening behavior during aging at 800 ℃ for 6000, 7000, 8000, and 10 000 h. The results indicate that the γ′ phase at the dendrites in the alloy is fine and uniform, while the γ′ phase between the dendrites presents two types. After long-term aging, the bimodal γ′ phase is still retained in the interdendritic region, and the γ′ phase transforms from spherical to cubic shape without any rafting phenomenon. During the long-term aging process, the γ′ phase size of the K439B increases, but the change in volume fraction is not significant. The variation of γ′ phase size with aging time conforms to both Lifshitz-Slyozov-Wagner (LSW) and theory of interface diffusion control (TIDC) models. The internal reason is believed to be the equivalent diffusion rate of elements between the matrix and interface.

• Preparation of WC-25Co Cemented Carbide by Laser Directed Energy Deposition and Its Tribological and Wear Properties

  Ye Nan, Li Shiyu, Wu Zichun, Mao Jie, Zhuo Haiou, Tang Jiancheng

  2025,54(2):497-504 DOI: 10.12442/j.issn.1002-185X.20240396

  Abstract(1) HTML(16) PDF(9.36 M)( 7)

  Abstract:WC-25Co cemented carbides were prepared by laser directed energy deposition technology using spherical WC-12Co composite powder and spherical Co powder as raw materials. The effects of laser power on the microstructure and friction and wear properties of WC-25Co cemented carbides were studied. The results show that the Co particles melt and form liquid phase, which significantly improves the deposition quality of WC-12Co. The increase in laser energy promotes the flow of Co liquid phase, and the densification degree and microstructure uniformity of the alloy are significantly increased. The alloy structure is composed of WC phase and Co phase, and no decarburization phases such as Co₃W₃C, Co₆W₆C and W₂C are found. With the increase in laser power, the alloy hardness increases gradually, and the wear rate decreases first and then increases. At the laser power of 1400 W, the wear rate in WC-25Co cemented carbide is the lowest, which is (0.81±0.11)×10^-5 mm³/(N·m). The wear mechanism is mainly abrasive wear, and there is also a small amount of oxidation wear.

• Hot-Deformation Behavior and Dynamic Recrystallization Rules of Hot-Rolled GH4141 Superalloy

  Zhang Xianguang, Pei Yiwu, Zhou Yang, Chen Jiajun, Xiao Dongping, Tang Pingmei, Fu Jianhui, Yan Jianhao, Zhang Jian

  2025,54(2):505-516 DOI: 10.12442/j.issn.1002-185X.20240447

  Abstract(6) HTML(18) PDF(22.26 M)( 11)

  Abstract:GH4141 nickel-based superalloy is a key material for turbine disks, fasteners and engine cases, which is generally fabricated through traditional casting-forging/rolling processes. In this study, the hot working behavior of hot-rolled GH4141 superalloy was studied. The hot deformation behavior of the hot-rolled GH4141 superalloy at deformation temperatures of 1050–1150 °C and strain rates of 0.01–1 s^-1 was studied through Gleeble hot-compression experiments, and the hot deformation constitutive equation of the alloy during the deformation process was constructed. In addition, based on the microstructure evolution analyses under different deformation conditions, the dynamic recrystallization rules during the hot deformation process were clarified. A dynamic recrystallization model of the alloy was constructed and the dynamic recrystallization fraction can be accurately predicted by this model. It is found that the dynamic recrystallization fractions are increased with the increase in the deformation temperature, the decrease in strain rate, or the increases in amount of deformation. From the viewpoints of degrees of dynamic recrystallization, the optimal deformation parameters are determined as deformation temperature at 1150 °C and the strain rate of 0.01–0.1 s^-1.

• Hot Compression Deformation Behavior of Extruded Mg-Mn-Ce Alloy Based on Arrhenius and BP-ANN Models

  Yang Yang, Wang Weijun, Yang Liu, Peng Hao, Jiang Hao

  2025,54(2):517-523 DOI: 10.12442/j.issn.1002-185X.20240547

  Abstract(1) HTML(16) PDF(3.95 M)( 7)

  Abstract:Hot compression tests were conducted on extruded Mg-Mn-Ce alloys under deformation temperatures of 723–873 K and strain rates of 0.0001–0.1 s^-1. Based on the obtained true stress-strain curve, the influence of deformation temperature and strain rate on material flow stress was analyzed. A constitutive relationship was established based on Arrhenius and BP-ANN models, and its accuracy was evaluated. Using the constitutive data obtained from the BP-ANN model, a hot processing map was plotted and numerical simulations were conducted. The results indicate that as the deformation temperature increases and the strain rate decreases, the flow stress of the alloy decreases. The BP-ANN model established has higher prediction accuracy, with a correlation coefficient of 0.9990 and an average relative error of only 2.69%. The hot working range of the alloy should be selected within the range of 0.001–0.01 s^-1 and 773–823 K. The numerical simulation and experimental results are in good agreement and can be used to guide the thermoplastic forming of alloys.

>Reviews

• Progress in Lamellar Metallic Materials

  Liu Xiaoxiao, Ma Shengguo, Qiao Junwei, Qiao Li, Wang Zhihua

  2025,54(2):533-544 DOI: 10.12442/j.issn.1002-185X.20240613

  Abstract(5) HTML(23) PDF(7.71 M)( 13)

  Abstract:Lamellar metallic materials comprising lamella units with different mechanical properties can form a unique lamellar heterostructured material. The heterostructures could induce various strength-ductility synergetic mechanisms due to the action of multi-type and multi-scale heterogeneity. Multiple lamellar morphologies have emerged with the diversification of material preparation means and processing treatments, and thus new requirements and design criteria have been derived for optimizing the lamellar microstructure. Optimizing the microstructural lamellar design and exploring the relation between mechanical behavior and micro/nano-lamellar structures will not only contribute to establishing the design theory about laminated metallic materials, but also accelerate its practical application. In this paper, the research progress on laminated metallic materials in recent years was reviewed. Classification of metallic lamellar structures, their mechanical properties and strength-ductility mechanisms were introduced and discussed in detail. Finally, perspectives on the future research trends and challenges of lamellar structures were briefly stated.

Online First

• Effects of Acetylene Gas on Mechanical Properties of DLC Film Prepared by Plasma-Enhanced Chemical Vapor Deposition

  Li Tong, Chang Yi Xiang, Zhang Tong, Zhang Yi, Yin Yan Sheng, Lu Jin Lin

  Available online:March 06, 2025  DOI: 10.12442/j.issn.1002-185X.20240677

  Abstract(4) PDF(1.10 M)(1)

  Abstract:Diamond-like carbon (DLC) films have many advantages,such as high hardness, low friction coefficient, and high chemical stability. They have been widely used for improving the surface hardness and wear resistance of light alloys. To improve the mechanical properties of 2024 aluminum alloy, a kind of DLC film was deposited on the surface of 2024 aluminum alloy by plasma-enhanced chemical vapor deposition technique.?The effects of acetylene gas on the microstructure, hardness, wear resistance and adhesion of DLC film were investigated by field emission scanning electron microscopy, nano-indentation, friction-wear test. The results indicate that the thickness of the?DLC film increased gradually with increasing the proportion of acetylene. There is an obvious transition layer between the DLC film and matrix. When the ratio of argon to acetylene is 1:3, the hardness of the DLC film was enhanced significantly because of the changes in the content of sp3 and sp2 bonds within the film. At the same time, the coefficient friction of the DLC film was reduced. This work provides an experimental and theoretical basis for improving the mechanical properties and enhancing durability of aluminum alloys.

• Research on the 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

  Available online:March 06, 2025  DOI: 10.12442/j.issn.1002-185X.20240835

  Abstract(15) PDF(1.59 M)(0)

  Abstract:The printing process and the debinding sintering process are carried out step by step, which can 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 75μm and inkjet density of 50% can ensure the density and compression strength of green parts, and have 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 density of 1060°C was 77.70% , the carbon residue formed pores to restrain the sintering process, and the density of 1070°C was 93.94% . It points out the direction for further optimizing the manufacturing process of binder jetting with pure copper.

• Research progress on the preparation of rhenium and rhenium alloy coatings under mild conditions

  wanghaoyan, Zhu Lian, wangzhen, baishuxin, yeyicong, tangyaguo

  Available online:February 26, 2025  DOI: 10.12442/j.issn.1002-185X.20240571

  Abstract(3) PDF(1.32 M)(4)

  Abstract:Rhenium has excellent physical and chemical properties, and has important applications in aerospace and military fields as ultra-high temperature structural material and surface cooling coating. There are many preparation methods for Re coating, but the mainstream preparation technology has high deposition temperature and corrosive atmosphere, which corrodes most refractory metal substrates. As a result, the mainstream preparation technology can not obtain dense and well-bonded Re coating on refractory metal and alloy substrate surface, which makes its application in high temperature protection of refractory metal surface limited. The preparation technology of Re coating under mild conditions is expected to solve this problem. This paper reviews the research status of Re coating preparation methods under three mild conditions: aqueous electrodeposition, MOCVD and EBPVD. The preparation processes and typical structure characteristics of Re coating by different methods are summarized, and the future research direction is prospected.

• Discrete element simulation and experimental study on the W-Cu homogeneous composites processed by high-pressure torsion

  Wang Xue, Zhu Yahui, Yang Cen, Gan Guoqiang, Li Ping, Xue Kemin

  Available online:February 26, 2025  DOI: 10.12442/j.issn.1002-185X.20240577

  Abstract(3) PDF(1007.33 K)(3)

  Abstract:The discrete element simulation of high-pressure torsion (HPT) deformation of W-Cu homogeneous powder material was carried out by PFC-3D software. The force chain and displacement distribution of particles during compression and torsion deformation were analyzed, and their effects on porosity, coordination number and equivalent stress in different regions were discussed. The simulation results indicate that the particle displacement exhibits a gradient distribution along both the compression direction and radial direction, with the maximum displacement located at the sample edge and on the upper surface. During the compression stage, particle rearrangement reduces the porosity rapidly, while shear deformation further promotes secondary particle rearrangement and rotation, which leads to a gradual decrease of porosity. The relative density and coordination number at the sample edge are higher than at the center, indicating that shear deformation with large torsional radius favors powder densification. Under the conditions of 400 °C and 1.5 GPa, HPT deformation was applied to the cold-pressed W-30Cu powder compacts with different turns. The experimental results show that with the increase of torsional radius and HPT turns, the degree of particle breakage, microstructure refinement and homogeneity are improved significantly. Under the combined effect of high hydrostatic pressure and shear force, the pores were elongated and enclosed, which results in the relative density increasing from 95.44 ± 0.87% after 10 turns to 96.03 ± 0.54% after 20 turns. The crystallite size of tungsten significantly reduces to 20.8 nm and the dislocation density rapidly increases to 2.35×101? m?2 after 15 turns and then the grain refinement and dislocation accumulation achieve the dynamic equilibrium. After 20 turns, due to the combined effects of powder densification, microstructure refinement and dislocation accumulation, the microhardness at the samples edge reaches 334.8 ± 4.2 HV, which represents an increase of approximately 78.7% compared to the sample center after 10 turns.

• Preparation and research progress of high temperature superconductors based on high pressure technology

  HuLe, HouHongli

  Available online:February 26, 2025  DOI: 10.12442/j.issn.1002-185X.20240592

  Abstract(1) PDF(825.78 K)(4)

  Abstract:From the discovery and preparation of metallic mercury superconductors to nickel-based superconductors, the study of the physical properties and microscopic mechanisms of superconducting materials has greatly promoted the development of condensed matter physics. The development of practical high-temperature superconductors based on new preparation technologies plays an extremely important role in the fields of strong and weak electricity. As a new means, high-pressure experimental technology has become one of the powerful tools for exploring novel superconductors and increasing the superconducting transition temperature (Tc) of superconductors. This paper takes three high-temperature superconductors H3S, LaH10 and HgBaCuO prepared by high pressure and high temperature as the objects, systematically summarizes the research progress of using high-pressure technology to control the superconductivity of high-temperature superconductors, explains the internal organization evolution of high-temperature superconductors under high pressure, clarifies the preparation ideas of practical high-temperature superconductors and the regulation mechanism of high pressure on their organization and superconductivity. The following main conclusions are drawn through analysis: high pressure helps to prepare LaH10, a hydrogen-rich compound superconductor with a special crystal structure, so that it can obtain a higher superconducting transition temperature; at the same time, high pressure can also affect copper oxide superconductors in a similar way to changing doping, thereby changing their superconductivity. High pressure technology is an effective way to obtain high temperature superconductors with special crystal structures (layered and cage). This paper reviews and analyzes the preparation technology of high temperature superconductors with high superconducting transition temperature and its progress, which can provide theoretical basis and experimental basis for the preparation of new high temperature superconductors by high pressure physics experiments.

• Interfacial and Mechanical Property Comparison of Cu/Al Composite Plates Manufactured by Rolling and Underwater Explosive Welding

  Available online:February 18, 2025  DOI: 10.12442/j.issn.1002-185X.20240745

  Abstract(29) PDF(1.11 M)(18)

  Abstract:Cu/Al composites are widely utilized across various industries due to their lightweight and excellent electrical conductivity. However, the impact of different manufacturing methods on the interfacial structure and mechanical properties of these composites remains significant. In this study, Cu/Al composite plates were fabricated using rolling and underwater explosive welding techniques to systematically compare their interfacial microstructure and mechanical performance. Interface morphology, grain orientation, grain boundary characteristics, and phase distribution were analyzed through optical microscopy, scanning electron microscopy, and electron backscatter diffraction. Mechanical properties were assessed using tensile shear tests, 90° bending tests, and hardness measurements, with Vickers hardness and nanoindentation tests providing further insight into hardness distributions. The results indicate that the diffusion layer in rolled Cu/Al composites is relatively fragile, while those produced by underwater explosive welding feature a diffusion layer approximately 18 μm thick, metallurgically bonded through atomic diffusion. The tensile shear strength of these composites ranges from 64.14 to 70.84 MPa, with superior flexural performance demonstrated in the 90° three-point bending test by the underwater explosive welded samples. This study elucidates the effects of distinct manufacturing methods on the interfacial properties and mechanical performance of Cu/Al composites, offering essential insights for selection of manufacturing method and application.

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

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

  Available online:February 17, 2025  DOI: 10.12442/j.issn.1002-185X.20240689

  Abstract(10) PDF(1.35 M)(11)

  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 after homogenization at 430 ℃ or 460 ℃ for 24 h followed by rolling are close to each other, and both are higher than that of the alloy homogenized at 490 ℃ for 24 h as 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 PSN (Particle Stimulated Nucleation) 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 close 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.

• Quantitative Analysis of Low Cycle Fatigue Fracture Stress in Nickel-Based Single Crystal Superalloys based on crack tip plastic zone

  Liu Xinling, Deng Zhiwei, Tian Fuzheng, Wang Xueyun, Li zhen

  Available online:February 17, 2025  DOI: 10.12442/j.issn.1002-185X.20240731

  Abstract(7) PDF(1.11 M)(13)

  Abstract:Low cycle fatigue failure is the main failure mode of tenon part of single crystal turbine blades. Due to the difference between the actual working load and the design load, the stress leading to fatigue failure often needs to be given after fatigue failure, and the fracture is a comprehensive reflection of load and temperature. Quantitative analysis of the fracture and inverse fatigue stress have important engineering application value in blade failure analysis. The unique microstructure and crystal structure of single superalloy make its fatigue fracture characteristics different from those of polycrystalline materials. The main fatigue fracture characteristics of single crystal superalloy are slip plane rather than fatigue band. A model and method for quantitative analysis of crack tip plastic zone are presented in this paper. There is a certain Angle between fatigue fracture and load of single superalloy, which is a composite cracking mode rather than a type Ⅰcracking mode. According to the cracking characteristics of single superalloy,, in this paper, using the test data of DD6 single-crystal high-temperature alloy under the condition of 530 ℃ and strain ratio r=0.05, the hysteresis return line of its different life intervals is analyzed, and the results show that: the life span is between one thousand and ten thousand times, and its hysteresis loop is very narrow; the life span is greater than ten thousand times, and its hysteresis loop is basically a straight line; it shows that DD6 single-crystal high-temperature alloy under the conditions of 530 ℃ and strain ratio r=0.05 has the small yielding characteristics. Based on this, for the low-week fatigue fracture, the characteristics of crack initiation and extension stage and its fracture characteristics were studied, and a quantitative analysis model of fatigue stress fracture was established by considering the composite cracking and based on rp in the plastic zone at the crack tip, use a total of 12 crack locations a for 3 specimens, the quantitative analysis of fatigue stress fractures at different a locations is carried out, and the analysis results show that the error of fatigue initiation stress was within 1.3 times, and that of inverse extrapolation result of the first stage of extension was within 1.5 times of the dispersion band. The results provide models and methods for quantitative fracture analysis of stresses in single-crystal high-temperature alloys mainly by slip-surface cracking (non-fatigue strips).

• Effect of Ar+ irradiation on microstructure and corrosion resistance of Zr-Sn-Nb alloy

  Hu Lijuan, Qiang Yuanyuan, Zhou Mingyang, Xin Yong, Gu Zhiyuan, Shi Jin, Xie Yaoping, Xu Shitong, Yao Meiyi, Zhou Bangxin

  Available online:February 17, 2025  DOI: 10.12442/j.issn.1002-185X.20240737

  Abstract(2) PDF(3.19 M)(5)

  Abstract:Irradiation can induce the formation of a large number of defects in the matrix and oxide film of zirconium alloys, thereby facilitating the migration and diffusion of O2- and corrosive media and accelerating the corrosion of zirconium alloys. To investigate the influence of irradiation on Zr-Sn-Nb alloys, Ar+ was implanted into the alloys at an irradiation fluence of 5.1×1015 ions/cm2. The original and irradiated samples were subjected to corrosion tests in an aqueous solution of 360 ℃/18.6 MPa/3.5 ppm Li + 1000 ppm B (alkaline water) and in steam at 400 ℃/10.3 MPa (neutral water), respectively. The microstructure was analyzed using XRD, SEM, and TEM characterization methods to study the effect of Ar+ irradiation on the corrosion resistance of Zr-Sn-Nb alloys in different corrosion environments. The results indicate that irradiation can lead to the amorphization of the second phase particles, among which the hcp-Zr (Fe,Nb)2 second phase is more likely to form an amorphous state than the bcc-β-Nb second phase. Furthermore, the second phase undergoes amorphization at the same time as element diffusion, and during the oxidation process of the second phase it experiences lattice mismatch with the oxide film, resulting in cracks extending from the top of the second phase to its sides. Within 300 days, the damage dose of Ar ion irradiation at 5 dpa has little effect on the corrosion resistance of Zr-Sn-Nb alloys in the aqueous solution of 3.5 ppm Li + 1000 ppm B. In contrast, in steam at 400 ℃/10.3 MPa, the stress relaxation during the irradiation process results in a reduction in defects, which subsequently slows down the oxygen diffusion within the oxide film and decelerates the corrosion process. Therefore, irradiation has a certain improving effect on the corrosion resistance of zirconium alloys.

• Effects of the addition of CNTs on microstructure, mechanics and thermal conductivity of pure copper in laser powder bed melting

  Laixia Yang, Longbo Zhang, Qidong Xie, Yanze Zhang, Mengjia Yang, Feng Mao, Zhen Chen

  Available online:February 17, 2025  DOI: 10.12442/j.issn.1002-185X.20240754

  Abstract(17) PDF(1019.58 K)(19)

  Abstract:The laser powder bed fusion (L-PBF) process for manufacturing copper typically exhibits poor strength-ductility coordination； the addition of enhancers is usually an effective way to improve it. However, there is relatively limited research on Cu composites. To explore the impact of enhancements on Cu, we used a Cu-CNTs mixed powder as the base and applied the L-PBF technology to produce a Cu-CNTs composite. We studied its forming performance, microstructure, and mechanical properties, as well as its conductive and thermal properties. The resulting composite has a high relative density of consolidated Cu-CNTs material. The addition of CNTs results in non-uniform microstructure with equiaxed grains at the edges of the melt pool and columnar grains at the center. Compared to pure copper, the overall mechanical properties of the composite are improved (tensile strength increased by 52.8%, elongation increased by 115.9%), and the electrical and thermal properties are also enhanced (thermal conductivity increased by 10.8%, electrical conductivity increased by 12.7%). The results indicate that the addition of CNTs can increase the tensile strength and elongation, as well as the electrical and thermal properties of copper. Therefore, this material provides an efficient pathway for designing more efficient heat sink structures.

• Effect of pore structure on forming quality and performance of Mg-5Zn magnesium alloy porous bone repair scaffold fabricated by SLM

  Zhao Lun, Sun Zhichao, Wang Chang, Zhang Pengsheng, Tang Shuai, Zhang Baoxin

  Available online:December 02, 2024  DOI: 10.12442/j.issn.1002-185X.20240618

  Abstract(110) PDF(1.94 M)(95)

  Abstract:Four types of Mg-5Zn porous scaffolds with different pore geometries, including body-centered cubic (BCC), rhombic dodecahedron (RD), primitive (P), and gyroid (G), were designed and fabricated using SLM. Their forming quality, compression mechanical properties, and degradation behavior were investigated. The results indicate the scaffolds fabricated exhibited good dimensional accuracy, and the surface chemical polishing significantly improved the surface quality while reducing forming errors. Compared to the rod structures (BCC, RD), the surface structures (G, P) scaffolds had less powder particle adhesion. For the same design porosity, the G porous scaffold exhibited the best forming quality. The predominant failure mode of scaffolds during compression was a 45° shear fracture. At a porosity of 75%, the compression performance of all scaffolds met the compressive performance requirements of cancellous bone, and BCC and G structures showed relatively better compression performance. Immersed in Hank"s solution for 168 hours, the B-2-75% pore structure scaffold exhibited severe localized corrosion, with fractures in partial pillar connections. In contrast, the G-3-75% pore structure scaffold mainly underwent uniform corrosion, maintaining structural integrity, and the corrosion rate and loss of compressive properties are less than those of the B-2-75% structure. After comparison, the G-pore structure scaffold is preferred.

• The Influence of Current Density and Copper Ion Concentration on the Properties of Electrodeposited Cu-Ni Coatings

  Xuyan Guo, Zhuangzhuang Xiong, Guixiang Wang, Qiang Zhou, Yanxiong Wu, Delong Kong, Fuqiu Ma, Ruizhi Wu

  Available online:November 21, 2024  DOI: 10.12442/j.issn.1002-185X.20240460

  Abstract(58) PDF(1000.11 K)(138)

  Abstract:This article investigates a straightforward, highly effective, and eco-friendly technique for preserving carbon steel surfaces against corrosion, by depositing Cu-Ni alloy coatings on the workpiece"s surface to impede corrosive medium. The effects of current density and Cu2+ concentration on the composition, morphology, and composition of the coating were investigated using scanning electron microscopy, X-ray energy dispersive spectroscopy, Vickers hardness tester, friction and wear tester, and electrochemical testing. A cauliflower like Ni rich protrusion structure appears on the coating surface. The lower current density and Cu2+ concentration affect the Vickers hardness and wear resistance of the coating by affecting the grain microstructure and Cu/Ni content, both leading a decrease in hardness and wear resistance. When the current density is 10 mA/cm2 and the Cu2+ concentration is 0.1 mol/L, the corrosion current density of the deposited sample reached 1.389×10?5 A·cm?2, and its surface corrosion damage was significantly less than that of the sample without coating after 24 h of salt spray test. Research on the deposition mechanism indicates that Cu2+ undergoes instantaneous nucleation under diffusion control, tending towards vertical growth and forming cauliflower-like protrusions, while Ni2+ is controlled by electrochemistry to discharge uniformly across the surface.

• Numerical simulation of the springback on magnesium alloy

  Malidong

  Available online:November 21, 2024  DOI: 10.12442/j.issn.1002-185X.20240464

  Abstract(40) PDF(602.94 K)(146)

  Abstract:The bending springback of magnesium alloys is difficult to predict accurately in numerical simulations because of its anisotropic characteristics. The springback of magnesium alloys in v-shaped roll bending was analyzed more accurately using the error optimization function in Matlab to optimize the anisotropic potential values required for the Hill’48 yield criterion in ABAQUS. The optimized Hill’48 yield criterion model was used to numerically simulate the springback of magnesium alloy v-shaped roll bending. The simulation results were compared with the experimental results. The error between the springback change ratio obtained using the optimized Hill’48 yield criterion and experimentally formed parts was within 2%. Overall, the optimized Hill’48 yield criterion model can improve the springback prediction accuracy of magnesium alloy v-shaped roll forming.

• Research on Welding Characteristics of Titanium Alloy Joints by Hollow cathode vacuum arc Welding

  Xu Jianping, Gong Chunzhi

  Available online:November 21, 2024  DOI: 10.12442/j.issn.1002-185X.20240470

  Abstract(34) PDF(1.20 M)(100)

  Abstract:The microstructure of Ti-6Al-4V joints by hollow cathode vacuum arc welding with different gas flow rate was studied, and the tensile properties were investigated. The results show that the microstructure of base metal was mixture of α phase β phase. The microstructure of heat affected zone are equiaxed and primary α and needle martensite α′ dispersed in the transformed β. Two kinds of tissues distribution depends on the heat-affected area affected by the welding thermal cycle.The microstructure of welding seam consists mainly of α′ martensite phase. Reduce welding gas flow rate and increase welding energy density, resulting in coarsening and more scattered distribution of martensitic grains. The tensile strength of welded joint is higher than that of base metal.

• Construction of bimodal-grained Mg-Bi alloy composed of ultrafine grains and fine grains and its strengthening and toughening mechanisms

  mengshuaiju, songjinlong, chenkeyi, cuimin, wanglidong, biguangli, caochi, yangguirong

  Available online:November 21, 2024  DOI: 10.12442/j.issn.1002-185X.20240480

  Abstract(66) PDF(921.12 K)(126)

  Abstract:Low-temperature equal channel angular pressing (ECAP) processing technology has great potential in fabricating bimodal-grained alloys composed of ultrafine grains and fine grains. Besides, fine grain Mg-Bi based alloys demonstrate excellent low temperature plastic deformation performance. Based on this, a new inverse temperature field ECAP (ITF-ECAP) processing method was developed to realize the severe plastic processing of a fine grained Mg-6Bi (B6) alloy at low temperature (<100 ℃) to construct a bimodal-grained microstructure composed of ultrafine (<1 μm) and fine grains (1-10 μm). The microstructure and mechanical properties characterization results show that dynamic recrystallization preferentially occurred at the initial grain boundaries of the fine-grained B6 alloy during the multi pass ITF-ECAP processing. Besides a large amount of submicron sized Mg3Bi2 phase precipitated during ITF-ECAP processing. As a result, bimodal-grained microstructure consisting of ultrafine grains with an average grain size (AGS) of about 600 nm and fine grain region with an AGS of about 2 μm was successfully constructed in B6 alloy through 4-pass ITF-ECAP processing. The volume fraction of the ultrafine grain region accounts for about 72.5 %. Due to the combined effects of grain-boundary strengthening, precipitation strengthening, dislocation strengthening, and back stress strengthening, the bimodal-grained B6 alloy exhibits excellent strength and ductility, with yield strength and elongation reaching 315.6±3.6 MPa and 22.3±1.0 %, respectively.

• Research Progress in Preparation of Titanium Matrix Composite Coatings by Cold Spraying: A Review

  Xu Yaxin, Zou Han, Huang Chunjie, Li Wenya

  Available online:November 21, 2024  DOI: 10.12442/j.issn.1002-185X.20240483

  Abstract(79) PDF(1.45 M)(145)

  Abstract:Cold spraying has great advantages in preparation of oxidization-sensitive metallic coatings because of the lower heat input and almost no oxidation resulting from its low temperature process. Combined with the convenience of cold spraying in manufacturing particle reinforced composite coatings, titanium matrix composite coatings prepared by cold spraying can compensate for the shortcomings of poor wear resistance of pure titanium or titanium alloys. In addition, one can also get the functional coatings besides the structural coatings. According to the existing research reports, the deposition behaviors and mechanisms of cold-sprayed titanium matrix composite coatings were summarized. By analyzing the porosity and deposition efficiency, the effect of strengthening on the microstructure of the cold-sprayed titanium matrix composite coatings was explained. The mechanism of reinforcement on mechanical and wear performance of titanium matrix composite coatings were revealed. Finally, the future application of cold-sprayed titanium matrix composite coatings is prospected, and several promising directions are listed.

• Analysis of the SLM forming structure and cracking mechanism of ZGH451 nickel-based high-temperature alloy

  wuyin, Zhang Hao, Zhu Yuping, Fang Shimin, Ding Yaoyao, Liang Liwen, Yan Guangqiang, Qiu Zixiang, Wang Haixuan, Dongye Shengshua, Tian Miaocheng, Yang Yang, Huang Qizhong, Zheng Yongjian

  Available online:November 21, 2024  DOI: 10.12442/j.issn.1002-185X.20240487

  Abstract(59) PDF(1.65 M)(128)

  Abstract:This study focuses on the SLM (Selective Laser Melting) formed ZGH451 nickel-based superalloy, revealing the mechanism by which solidification liquid films lead to crack initiation and clarifying the roles of alloy elements and texture in forming crack defects. Experimental results indicate that cracks in the SLM process of ZGH451 nickel-based superalloy can be mainly categorized into internal solidification cracks and edge cold cracks. During the late solidification stage, low-melting-point phase liquid films exist between dendrites, and high-melting-point Cr element particles at the solidification front hinder melt feeding. The insufficient feeding and thermal stress between dendrites cause the liquid film"s rupture, leading to solidification cracks in the core of the material. In the alloy"s contour region, high cooling rates and significant thermal stress lead to residual stress accumulation, which exceeds the material"s strength limit or grain boundary cohesion strength, resulting in the formation of cold cracks. When the input laser energy density is below 53.6 J/mm3, pores and lack of fusion defects increase significantly in the alloy, while exceeding 130.9 J/mm3 sharply increases the probability of keyhole formation along the melt pool track. These defects can induce cracks under stress. The more TiC and other carbide particles precipitate between dendrites, the greater grain misorientation, and the higher the alloy"s crack sensitivity. The deposited state of ZGH451 nickel-based superalloy is mainly composed of γ and γ" phases, with a preferred orientation on the (100) plane. The average aspect ratio of the grains reaches 11.25, and the significant texture exacerbates stress concentration at the grain edges and tips, promoting crack initiation and altering crack propagation direction.

• The Effect of Different Heat Treatments on Surface Microstructures and Anodic Oxide Film Structures of an Al-5.6Mg Alloy Sheets

  jiangzhongyu

  Available online:November 21, 2024  DOI: 10.12442/j.issn.1002-185X.20240492

  Abstract(24) PDF(833.41 K)(131)

  Abstract:The effect of different intermediate annealing heat treatments on the surface microstructures and anodic oxide film structures of rolled sheets of an Al-5.6Mg alloy was studied. The results show that when the continuous annealing is used instead of the static state annealing in intermediate annealing process to control microstructures of the sheets, the surface grain size of the sheets can be reduced by about 60 %, and size of the Mg precipitated phase (Mg2Al3) can be reduced by about 67 %. Under the combined influence of grain size, uniform precipitation phase, and texture, the highest glossiness can be obtained, which was attributed to continuous intermediate annealing and stabilization annealing at low temperature. The uniform grain and precipitation structures is beneficial to reduce the inhomogeneous dissolution of the oxide film and to obtain the anodic oxide film with uniform thickness and high gloss.

• The Influence of Ni Interlayer Thickness on the Microstructure and Mechanical Properties of Zr-4/Nb/Ni/316SS Diffusion Bonded Joint

  Li Qianru, Zhang Fan, Niu Shiyu, Wang ying, Yang Zhenwen

  Available online:November 21, 2024  DOI: 10.12442/j.issn.1002-185X.20240495

  Abstract(56) PDF(1.24 M)(160)

  Abstract:This study systematically investigates the influence of Ni interlayer thickness on the microstructure, mechanical properties, and corrosion resistance of Zr-4/Nb/Ni/316SS diffusion bonded joints. The experimental results reveal that the typical interface microstructure of the joints consists of Zr-4/β-(Zr, Nb)/Nb/Ni3Nb/Ni/316SS. The shear strength of the joints initially increases and subsequently decreases with increasing Ni interlayer thickness, reaching a peak value of 380 MPa at an interlayer thickness of 30 μm. To elucidate the effect of Ni interlayer thickness on the mechanical properties, the microstructural characteristics of the joint interfaces were characterized, and Abaqus simulations were conducted to analyze the residual stress distribution across the interfaces. The comparative analysis of the mechanical properties and fracture behavior, combined with simulation results, indicates that while thicker Ni interlayers are more effective in alleviating residual stress, excessively thick interlayers lead to a reduction in shear strength due to their enhanced ductility. Additionally, the corrosion resistance of the joints was assessed using full immersion corrosion tests. The results indicate that the corrosion rate decreases with a reduction in Ni interlayer thickness, with the optimum corrosion resistance observed at an interlayer thickness of 10 μm. In conclusion, it is recommended that the Ni interlayer thickness be maintained between 10 μm and 30 μm to achieve a balance between mechanical properties and corrosion resistance.

• Study on thermal stability of W-Re alloy and influence of high temperature oxidation behavior temperature

  Nan Lingxin, Qi Yanfei, Xu Pengfei, Li Yungang, Pang Binghe

  Available online:November 21, 2024  DOI: 10.12442/j.issn.1002-185X.20240509

  Abstract(103) PDF(1.33 M)(132)

  Abstract:Superalloy has a very important position in the development of nuclear fusion and other fields, and the use of the requirement is to form a stable and protective oxide under high temperature service conditions, and the oxide can prevent further oxidation of the alloy. In order to study the stability and oxidation resistance of W-3%Re alloy at high temperature, the thermal stability experiments of W and W-3%Re alloy were carried out at (500,700,900 ℃) for 6h. Oxidation experiments were carried out at different temperatures (700,800,900 ℃) for 18h. The phase composition, oxidation kinetics, oxidation products and surface morphology of the oxide film were analyzed by XRD, SEM, LSM800 automatic 3D morphology analyzer and Hysitron TI Premier Nanoindentation apparatus. The results show that the quality of the alloy increases with the extension of oxidation time. During the oxidation process, the grain size of W-3%Re alloy is reduced, the oxidation film can be formed faster, the surface oxide layer is gradually thicker, and the high temperature oxidation resistance of W-3%Re alloy is improved. Compared with W, the chemical stability of the Re oxide in W-3%Re alloy is higher, and it shows a lower oxidation rate constant when it is oxidized at 700℃ for 18h. At this time, the W-3%Re alloy is a weak oxidation grade, and the density of the oxide layer is improved to a certain extent during the oxidation process. The results show that the addition of Re can improve the high temperature oxidation resistance of W material.

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