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  • Thermal Stability and Thermoplastic Formability of Pd20Pt20Cu20Ni20P20 High Entropy Metallic Glass
  • 2024 Special Issue on Amphous and High Entropy Alloys
  • Residual Stress Relaxation of 2A02 Blade Forging Under Electromagnetic Coupling Energy
  • Effect of Mo on Microstructure and Properties of AlCoCrFeNiMox High Entropy Alloy Coatings Prepared by Laser Cladding
  • Uniform Elongation and Yield-Drop Phenomenon in Magnetically Annealed 1050 Aluminum Alloy Prepared by CryoECAP
  • Effect of Heat Treatment on Microstructure and Properties of Titanium Alloy Welded Joint by Laser Welding with Flux-Cored Wire
  • Deposition Behavior of HVOF Sprayed WC-12Co Particles on AA7075
  • Effect of Primary α-Phase on Micro-area Plastic Deformation of Ti6242s Alloy Under Dwell Fatigue
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    2024,Volume 53, Issue 1

      >Amorphous And High Entropy Alloy
    • Sandrine Cardinal, Jean-Marc Pelletier, Hidemi Kato

      2024,53(1):1-7 DOI: 10.12442/j.issn.1002-185X.20230842

      Abstract:Thermal stability and thermo-mechanical properties of Pd20Pt20Cu20Ni20P20 high entropy metallic glass (HEMG) were investigated by differential scanning calorimetry, X-ray diffraction, and thermomechanical analysis. Results show that compared with other classical precious metal-based metallic glasses, Pd20Pt20Cu20Ni20P20 HEMG presents comparable performance with distinct characteristics.

    • Zhao Yanchun, Song Haizhuan, Ma Huwen, Feng Li, Liu Jianjun, Duan Wangchun

      2024,53(1):102-112 DOI: 10.12442/j.issn.1002-185X.20230272

      Abstract:At present, the traditional design concept of alloying materials based on enthalpy change is approaching its limit, while new metal materials based on entropy change design have a large degree of freedom in the design of medium and high entropy alloys, which make up for the shortcomings of room temperature brittleness and metastable crystallization of metastable materials and continuously make breakthroughs in performance. Laser additive manufacturing technology differs from traditional processing design and manufacturing concepts, providing new possibilities for promoting the development of advanced alloy materials and has become a key technology for linking materials and products. In this paper, based on laser additive manufacturing technology, the research status of high-entropy alloy coating prepared by laser cladding technology, high-entropy alloy prepared by 3D printing technology and high-entropy high-temperature shape memory alloy prepared by 4D printing technology are described from three dimensions of 2D, 3D and 4D, respectively. The key technical problems and solutions in the current research are discussed. Finally, the preparation of advanced alloy materials by laser additive manufacturing technology is summarized and prospected.

    • Peng Zhen, Guo Qingyu, Sun Jian, Li Keran, Luan Hengwei, Gong Pan

      2024,53(1):17-22 DOI: 10.12442/j.issn.1002-185X.E20230033

      Abstract:Tribological properties of Al19Fe20-xCo20-xNi41Mo2x (x=0, 1, 2, 3, 4, 5) eutectic high-entropy alloys (EHEAs) were investigated in this research. Results show that EHEAs with trace Mo addition can form the face-centered cubic (fcc)+B2 eutectic microstructure, whereas EHEAs with relatively higher Mo content can form fcc+B2+μ dendritic microstructure. Mo element is beneficial to the strength enhancement of L12 phase and the ductility improvement of B2 phase. However, with increasing the Mo content to x>2, the resultant Mo-rich μ phase degrades the strength and plasticity of EHEAs. Al19Fe18Co18Ni41Mo4 EHEA has the optimal combination of high strength and high ductility. Increasing Mo content can improve the oxidation resistance of EHEAs. With increasing the Mo content, EHEA forms a tribo-oxide layer with improved oxidation resistance during sliding process, and the friction coefficient is monotonically decreased. This research provides guidance for the investigation of tribological properties of Al19Fe20-xCo20-xNi41Mo2x EHEAs.

    • Xiao Haiyang, Lyu Guojian, Qiao Jichao

      2024,53(1):23-30 DOI: 10.12442/j.issn.1002-185X.E20230041

      Abstract:To understand the dynamic mechanical properties and thermodynamic stability of β-Ti phase-embedded Zr/Ti-based bulk metallic glass composites (BMGCs), (Ti0.474Zr0.34Cu0.06Be0.126)100-xFex (x=0, 2) BMGCs were prepared and investigated. Results show that by introducing Fe element, the stability of β-Ti phase is improved. An abnormal internal friction peak can be observed due to the precipitation of ω-Ti in the metastable β-Ti phase. Below the glass transition temperature Tg, both BMGCs show abnormal overshoot on storage modulus due to the coupling effect of phase transition and partial crystallization of amorphous matrix. This research provides information about the complex dynamic mechanical relaxation behavior of the in-situ metastable β-Ti BMGCs.

    • Li Xiaocheng, Kou Shengzhong, Zhao Yanchun, Li Chunyan, Li Chunling

      2024,53(1):31-37 DOI: 10.12442/j.issn.1002-185X.E20230034

      Abstract:Based on the glass-forming ability (GFA) during cooling process and the glass stability (GS) of heating process, a triangle to evaluate GFA and GS, namely Tri-FAS, with the combination of pseudo-four characteristic parameters as vertices was established. Accordingly, a GFA&GA criterion (G-FAS) was deduced as G-FAS=Tg/Tl+Tx/Tl+Tx/Tg (Tx is onset crystallization temperature; Tl is liquid temperature; Tg is glass transition temperature). Additionally, the criterion was modified based on the competitive relationship between amorphous phase and crystal phase during cooling process and the contribution of each component to the criterion: G-FASm=Tg/(1.5Tx)+Tx/Tl+Tx/Tg and G-FASm′=Tg/Tl+Tx/Tl+(Tx/Tg)a (a≈1.5±0.2). The correlation between G-FAS and critical cooling rate Rc and that between G-FAS and Txg (Txg reflects the supercooled liquid region of glass, Txg=Tx/Tg) were discussed, which could reflect GFA and GS, respectively. Through the determination results of GFA and GS of abundant metallic glasses and other glass formers, the validity of the proposed G-FAS criterion was evaluated. Results show that with respect to both GFA and GS, the G-FAS criterion is reliable in various glass former systems, showing wide applications. The proposed Tri-FAS and G-FAS criterion can provide guidance during the fabrication and application of metallic glasses.

    • Zhang Yunsheng, Jiang Xueyu, Zhou Ge, Zhang Haoyu, Zhang Siqian, Che Xin, Chen Lijia, Cao Xue

      2024,53(1):38-46 DOI: 10.12442/j.issn.1002-185X.E20230037

      Abstract:The single-pass thermal compression experiments were conducted on NiCoFeCrAl high entropy alloy by Gleeble-3800 thermal simulation tester. The Arrhenius constitutive model was established based on the peak stresses. With four instability criteria (Prasad, Murty, Gegel, and Malas), different heat processing maps of dynamic material model were established. The applicable ranges of the instability criteria for the alloys in the heat deformation process were analyzed and compared. Results show that the optimal heat processing ranges of the alloys are the temperature range of 980–1010 °C+strain rate of 0.01–0.001 s-1 and the temperature range of 1050–1100 °C+strain rate of 0.01–0.1 s-1. The average power dissipation rate is greater than 36%. Through EBSD microstructure analysis, the softening mechanism of thermal deformation is changed from dynamic recovery to dynamic recrystallization with increasing the deformation amount.

    • Mehran Nabahat, Duan Yajuan, Xu Zongrui, Qiao Jichao, Eloi Pineda

      2024,53(1):47-55 DOI: 10.12442/j.issn.1002-185X.E20230837

      Abstract:Due to the disordered structure of amorphous alloys, the complex structural dynamics involves the particle rearrangements with a large span in time and size scales. The characterization and mechanism of structural dynamics of amorphous alloys are crucial and fundamental for the further research of relaxation behavior and physical aging kinetics of glasses. Abundant researches show that the relaxation spectra of rare-earth-based amorphous alloys, which are represented by lanthanum- and cerium-based alloys, show obvious secondary relaxation process, and the system becomes an ideal carrier to investigate the relationship between structural dynamics and mechanical properties of amorphous alloys. In this review, the anelasticity of metallic glasses was discussed. The anelastic deformation, as the main component of deformation, can totally recovery after unloading in creep experiments, and its mechanism is important to form deep understanding about the structural dynamics of metallic glasses. Additionally, the main characteristics of anelastic deformation during creep and creep recovery were summarized, and some theoretical models for quantitative and qualitative description were introduced.

    • Xue Yuan, Shan Guibin, Pan Ruilin, Tang Song, Lan Si

      2024,53(1):56-69 DOI: 10.12442/j.issn.1002-185X.E20230042

      Abstract:In recent years, high-entropy alloys (HEAs) have become the research hotspot in the field of metal structural materials because of their novel design concepts and excellent physicochemical properties. With the continuous popularization of lightweight alloy design concepts, the conception of “entropy regulation” has been widely used to develop new lightweight alloys. Lightweight HEAs (LHEAs) are a new type of low density HEAs based on lightweight alloy designs. Their development and design mainly combine the empirical parameter criteria, phase diagram calculations, and first-principles calculations. Al-Ti-V-based LHEAs attract much attention among various LHEAs due to their excellent mechanical properties, good high temperature oxidation resistance, and fine corrosion resistance. This paper summarized the research progress of Al-Ti-V-based LHEAs from the perspective of composition design, preparation methods, microstructures, and physicochemical properties. Meanwhile, the problems and challenges for Al-Ti-V-based LHEAs were also prospected.

    • Wang Bing, Gao Xuanqiao, Qiao Jichao

      2024,53(1):70-77 DOI: 10.12442/j.issn.1002-185X.E20230821

      Abstract:The relaxation dynamics of metallic glasses, as one of the most challenging issues, is complex. The relaxation, including α relaxation, slow β relaxation, and fast β relaxation, occurs at different temperatures. Taking advantage of the microscopic atomic information of simulation, the characteristics and mechanisms of these three typical relaxations were summarized to discuss their influence on mechanical properties of metallic glasses. Recent progresses on dynamical, structural, and physical mechanisms by simulation method were discussed. This review is beneficial to understand the nature of glass and to establish the dynamics-structure-property relationship of glassy materials.

    • Wang Liyuan, Jiang Jiali, Wang Dengke, Zhang Yi, Wang Qing, Lu Jian

      2024,53(1):78-84 DOI: 10.12442/j.issn.1002-185X.E20230738

      Abstract:The control of atomic-scale structure of metallic glasses (MGs) to improve their physical, chemical, and mechanical properties is an essential issue. Over past decades, large efforts have been devoted into the development of effective MG control approaches, such as the cryogenic treatment (CT) technique. This research reviewed the effects of cryogenic treatment on the properties and their dependence on the initial structural energy state of MGs. Then, it focused on the atomic-scale structure evolution in MGs during CT, which is of fundamental importance to understand CT effects.

    • Pu Yongliang, Qian Yiqi, Liu Yuxin, Liu Cong, Ding Jing, Zhu Shengli

      2024,53(1):8-16 DOI: 10.12442/j.issn.1002-185X.20230569

      Abstract:In order to improve the thermal stability and to obtain a large supercooled liquid region of metal glasses, the Zr65-x(Al0.21Ni0.29Cu0.04Ag0.46)35+x (x=0, 7.5, 15.0, 22.5) metallic glasses were investigated. The effects of component concentrations on the thermal stability, heat-induced precipitate phases, and mechanical properties were analyzed. Results show that with increasing the component concentrations, the peak position of the broad diffraction pattern shifts towards higher angles, indicating the occurrence of glass transition phenomenon. With increasing the glass transition temperature (Tg) and crystallization temperature (Tx), the liquidus temperature (Tl) is decreased, leading to decrease in the temperature difference (namely supercooled liquid region, ΔTx) between Tx and Tg and resulting in the increase in reduced glass transition range (Trg). Additionally, the nucleation activation energy (Ex) and the growth activation energy (Ep1) are increased with increasing the solute concentration. The primary crystal changes from the combination of tetragonal Zr2Ni, Zr2(Cu, Ag), ZrAg, and hexagonal Zr5Al3 phases into the single tetragonal ZrAg phase. The Vickers hardness is also increased with increasing the solute concentration. In this research, a novel metallic glass, Zr65-x(Al0.21Ni0.29-Cu0.04Ag0.46)35+x (x=7.5), is developed, which presents a large ΔTx of 141 K, high thermal stability, and strong crystallization resistance. This research adopting the multicomponent replacement strategy is of great significance to improve the thermal stability of metallic glasses.

    • Feng Li, Wang Mengqi, Zhao Yanchun, Li Qiuda

      2024,53(1):85-94 DOI: 10.12442/j.issn.1002-185X.20230571

      Abstract:This study employs vacuum arc melting technology to fabricate FeCrMnAlCux (x=0, 0.5, 1.0, 1.5, 2.0) high-entropy alloys. The phase structure and microstructure of the alloys before and after corrosion were characterized using XRD, SEM, and EDS. The corrosion behavior of the alloys in 0.5M H2SO4 solution was analyzed through potentiodynamic polarization curves, EIS, XPS, and immersion tests. The results indicate that the addition of Cu promotes the formation of the FCC phase in the alloy, transforming it from a single BCC structure to a mixed BCC+FCC dual-phase structure. The high-entropy alloys with five different compositions exhibit a typical dendritic morphology. As the Cu content increases, the grains gradually refine, and the microstructure becomes more uniform. The FeCrMnAlCu1.5 high-entropy alloy has the highest corrosion potential (-0.363 V) and the lowest corrosion current density (2.148×10-5 A/cm2). The alloy"s corrosion resistance initially improves and then deteriorates with increasing Cu content. At x=2.0, the corrosion potential decreases to -0.394 V, and the current density increases to 2.865×10-4 A/cm2, yet its corrosion resistance is still superior to that of the alloy without added Cu. After corrosion, a composite oxide protective film forms on the cross-section of the alloy, effectively reducing its corrosion rate in 0.5M H2SO4 solution.

    • Li Yuan, Yang Zhong, Duan Hongbo, Yang Wei, Wu Chao, Li Jianping

      2024,53(1):95-101 DOI: 10.12442/j.issn.1002-185X.20230326

      Abstract:: The first density functional theory and virtual crystal approximation (VCA) method were used to establish the crystal structure model, and the structural properties, elastic properties and heat of energy of high entropy alloy Al0.4Co0.5VxFeNi were calculated. According to the minimum energy principle, the optimal K-point value of Al0.4Co0.5VxFeNi high entropy alloy is 12×12×12, and the cutoff energy is 1000eV. The results show that FCC+BCC structure can be formed by Al0.4Co0.5VxFeNi alloy, and the mechanical stability of FCC is obviously better than that of BCC. When V content increases from 0.2 to 0.8, BCC lattice constant decreases by 4% and FCC lattice constant decreases by 6%. The bulk modulus and shear modulus of Al0.4Co0.5VxFeNi alloy decrease with the increase of V element. When the content of element V is 0.8, the Poisson"s ratio of BCC structure increases abnormally, which further indicates that with the increase of element V content, the plastic deformation capacity of materials decreases and the brittleness of materials increases. The experimental results show that Al0.4Co0.5VxFeNi alloy is composed of FCC and BCC, and its microstructure is two-phase. When the content of element V decreases from 0.2 to 0.8, the elongation decreases by ~85%. The experimental result is the same as that calculated by the first principles.

    • >Reviews
    • Wang Nan, Li Jinguo, Liu Jide, Xu Wei

      2024,53(1):257-269 DOI: 10.12442/j.issn.1002-185X.20220927

      Abstract:Additive Manufacturing (AM) is an advanced digitalized technology that has been extensively applied in the fabrication of high temperature alloys. This paper reviews the microstructure of high temperature alloys prepared by AM, summarizes the type and features of pores, and categorizes the development of models interpreting the formation of cracks. The application of computational science in the research of preparation of high temperature alloys was also reviewed. Finally, the prospect of AM in the research and development of high temperature alloys was discussed.

    • Du Shengmin, Wang Qingxiang, Zhang Shiming, Wang Ruifang, Che Yusi, He Jilin

      2024,53(1):270-280 DOI: 10.12442/j.issn.1002-185X.20220975

      Abstract:Due to its low coefficient of thermal expansion, high temperature strength, high elastic modulus and other characteristics, molybdenum metal is widely used in aerospace, military, petrochemical and nuclear industries and other cutting-edge industries, is an indispensable material to promote the development of high-tech fields. Molybdenum powder as the basic material of molybdenum products, its physicochemical properties are closely related to the properties of molybdenum products. Compared with ordinary molybdenum powder, superfine molybdenum powder has larger specific surface area, higher activity and lower sintering temperature. At present, the main methods for preparing ultrafine molybdenum powder are thermal reduction method and thermal decomposition method. Thermal reduction method can prevent grain growth by adjusting the reduction process. The development of thermal decomposition method mainly involves the upgrading of equipment and the optimization of process. In this paper, focusing on the preparation process, reaction mechanism and product state of superfine molybdenum powder, the development process and technical characteristics of the typical process were analyzed, the research status and progress of the preparation technology of superfine molybdenum powder were summarized, and the problems faced by the current technology and the future research direction were put forward, in order to provide ideas for the development and industrial application of the preparation technology of superfine molybdenum powder.

    • Chen Leihao, Dong Yiwei, Yang Hongwei, Mao Huaming, Ren Yu

      2024,53(1):281-295 DOI: 10.12442/j.issn.1002-185X.20220962

      Abstract:Heterojunction solar cells have the advantage of high cell efficiency and show great potential in the field of solar photovoltaics. Low-temperature metallization is an important process in the manufacturing of heterojunction solar cells, which is used to form metal grids on the cell surface. Currently, low-temperature-cured silver paste combined with screen printing is widely used to achieve this. However, the high consumption of expensive low-temperature silver paste is one of the reasons for the high cost of the cells. The photovoltaic industry is working hard to improve and optimize metallization process to reduce silver consumption. This paper reviews the recent progress on metallization technologies for heterojunction solar cells, and summarizes in detail how the components of low-temperature silver paste as well as the curing process affect the overall performance. In addition, the main metallization approaches used to increase cell effectiveness are introduced and compared, including silver paste reduction strategies such as multi-busbar and pattern transfer printing technologies, and non-silver metallization strategies such as silver-coated copper and copper plating technologies. Finally, the current challenges of different metallization process for heterojunction solar cells are analyzed and their future development are also prospected.

    • Ma Limin, Lu Ziyi, Jia Qiang, Wang Yishu, Zhang Hongqiang, Zhou Wei, Zou Guisheng, Guo Fu

      2024,53(1):296-320 DOI: 10.12442/j.issn.1002-185X.20230170

      Abstract:With the rapid development of the third-generation semiconductors SiC and GaN, traditional packaging materials such as Si-based lead-free solder cannot satisfied the requirements of high-power density and high-temperature loadings in power electronic devices any more. Nowadays, the joints packaged by Cu nanoparticle sintering technology could not only be bonded at low-temperature and serving at high-temperature, but also exhibit excellent thermal conductivity, electrical conductivity and relatively lower cost comparing to Ag nanoparticles. Thus, more and more attentions has been attracted in the field of Cu nanoparticle sintering technology using in power electronic packaging, which makes Cu nanoparticles become one of the most potential high-temperature-resistant packaging and interconnection materials. In this work, the current research progress of Cu nanoparticle sintered technology was summarized, including the fabrication of Cu nanoparticle pastes, the factors affecting the performance of sintered joints and the reliability of joints. Meanwhile, the oxidation behaviors as well as the anti-oxidation methods of Cu nanoparticle were introduced. Also, the high-temperature working reliability and failure mechanism of Cu nanoparticle sintered joints were discussed. This review was aimed at promoting the application of low-cost Cu nanoparticle sintering technology for high-performance and high-reliability power electronic packaging.

    • >Materials Science
    • Wangchen, Wang Xingmao, Yu Hongyao, Wang Lianbo, Wang Rui, Cheng Tijuan, Guo Caiyu, Bi Zhongnan, Wang Zhanyong

      2024,53(1):113-123 DOI: 10.12442/j.issn.1002-185X.20230007

      Abstract:The mechanical properties and deformation mechanism of a novel Ni-Co-based superalloys at room temperature (25 ℃) and medium temperature (650 ℃, 700 ℃ and 750 ℃) were studied using SEM, EBSD and TEM. The results show that the yield strength and elongation rate of the alloy were 1176 MPa and 22.5% respectively at room temperature, and the decreasing trend with temperature increase. At room temperature, the main deformation mechanism is that a large number of dislocations slip, and the partial dislocations shear the γ′ particles into isolated stacking faults. When the temperature reaches 650 ℃, it is observed that microtwins run through the secondary γ′ particles and γ matrix,but it is mainly deformed that continuous stacking faults shearing secondary γ′ particles and γ matrix. At 700℃-750℃, the secondary γ′ particles and the γ matrix are sheared simultaneously by continuous stacking faults and microtwins, and the length of stacking faults and thickness of microtwins increase with temperature. In the 650 ℃-750 ℃ range, the mechanism for shearing a γ′ particles once transitions from APB to isolated stacking faults. This study discusses the variation of deformation mechanism with temperature and the formation mechanism of microtwins and stacking fault under medium temperature conditions. An atom interchange diffusion model for SEFS formation of a/6 <112> partial dislocation shear γ′ particles is presented, which explains the formation process of microtwins and provides a reference for the further development of novel Ni-Co-based superalloys with high performance level.

    • Wang xudong, Li pengyu, Tang sifan, Yue yixin, Yao man, Dong wei

      2024,53(1):124-135 DOI: 10.12442/j.issn.1002-185X.20220987

      Abstract:The preparation of micron-sized spherical particles by the Pulsed Orifice Ejection Method (POEM) is a typical unconstrained heat transfer and solidification process, and the prepared spherical particles have the characteristics of uniform particle size, high roundness and consistent thermal history. The heat transfer mechanism dominated by convection and radiation is crucial for the preparation technology, solidification process and microstructure control. According to the preparation process, heat transfer and solidification characteristics of micron-sized spherical metal particles by POEM, a numerical calculation model of heat transfer and solidification in a three-dimensional spherical coordinate system is established in this paper. The proposed model considers the behavior of the convection and radiation heat transfer of pure Cu particles in the unconstrained solidification process, and adopts the temperature recovery method to deal with the latent heat of pure metal solidification. The temperature variation and distribution of spherical particles at different solidification stages are calculated, and the temperature gradient, cooling rate, liquid-solid interface movement and solidification rate during the solidification process are also investigated. In addition, the convective and radiative heat transfer and their contribution are simulated and analyzed, and the effects of different preparation processes on the convective heat transfer of the particles are explored. The results provide references for the optimization of the preparation and the regulation of the solidification process of micron-sized spherical particles by POEM.

    • Zhang Xianguang, Chen Jiajun, Yang Wenchao, Zhou Yang, Xiao Dongping, Tang Pingmei, Fu Jianhui, Shi Peng, Pei Yiwu, Yan Jianhao, Sun Fei, Zhang Jian

      2024,53(1):136-147 DOI: 10.12442/j.issn.1002-185X.20230481

      Abstract:GH4141 wrought superalloy is widely used in the manufacture of high-temperature load-bearing components for aerospace engines due to its high strength and good oxidation resistance at high temperatures. In this paper, based on chemical composition analysis and crystallographic method, the typical precipitates in the as-cast GH4141 alloy were identified and analyzed in detail. The dissolution behaviors of the precipitates during the homogenization process were analyzed through the high-temperature homogenization experiments. Under the medium and low temperature homogenization conditions of 1130~1160 oC, the needle-like σ phase, plate shape η phase, M3B2 boride and γ’ strengthening phases of the original as-cast structure are dissolved into the matrix, while the M6C carbide can still be existed. Under the condition of high temperature homogenization at 1190~1210 oC, most of the precipitates including M6C in the alloy have been dissolved into the γ matrix, and only a small part of MC carbides remain in the structure. Besides, it’s worth noting that the MC carbides are dissolved in the solid-liquid two-phase region, and the MC carbides are difficult to be completely dissolved and eliminated through homogenization heat treatment.

    • Qin Lanyun, Zhang Jingjing, Wang Wei, Yang Guang

      2024,53(1):148-158 DOI: 10.12442/j.issn.1002-185X.20220964

      Abstract:Laser deposition manufacturing (LDM) technology has unique advantages in additive manufacturing of large aircraft frames and beams. However, stress and deformation have become bottlenecks that hinder the application of this technology. Therefore, the islands process is widely used to discrete the residual stress and alleviate the deformation of the parts. However, the traditional islands process does not take into account the geometric structural features of parts easily lead to irregular partition lap, which introduced pores, poor fusion and other defects. In order to solve this problem, a feature islands method is proposed. According to the geometric shape characteristics of the slicing layers of typical frame and beam structural parts, The features are classified into four types: “十”-shape, T-shape, L-shape and “一”-shape features, and all kinds of features are limited from three aspects :shape, pose and size to complete the definition of island features. A feature recognition algorithm based on region skeleton line detection is proposed, where the skeletonization is used to effectively simplify the features and retain the part characteristics. The vector cross-product and fixed-ratio point method are used to calculate the relevant parameters such as feature angle, plane attitude angle and number of feature branches. Feature type identification is achieved by comparing calculated values with defined values. The algorithm is verified by slice data of a typical aircraft frame model. The results show that the algorithm can quickly and accurately identify various features to realize automatic feature islands of parts, which lays a foundation for intelligent additive manufacturing technology.

    • Gai Yongchao, Zhang Rui, Zhou Zijian, Lv Shaomin, Cui Chuanyong, Qu Jinglong

      2024,53(1):159-168 DOI: 10.12442/j.issn.1002-185X.20220996

      Abstract:GH4151 alloy is a new type of casting and deformation superalloy of turbine disk with the temperature bearing capacity up to 800 ℃. The alloy has severe elemental segregation during solidification, main segregation elements including Nb, Ti and Mo element. Meanwhile, the alloy contains a large amount of C element. In the late stages of solidification, due to the enrichment of elements in the residual liquid phase, a large number of harmful phases, including (γ-γ′) eutectic, Laves phase, η phase and MC carbides, precipitate between the dendrites. By studying the influence of C content on the segregation elements, it is found that increasing C content can reduce the segregation of Nb elements between dendrites. In addition, with the increase of C content, the dendrites become more developed and the inter-dendrite area decreases. The melting points were determined by studying the effects of homogenization heat treatment at different temperatures from 1160 ℃ to 1210 ℃ that (γ-γ") eutectic and Laves phases are about 1180 ℃, η phase is about 1200 ℃ and MC carbide is more than 1300 ℃. At the same time, it is found that the 1170 ℃/16 h-1200 ℃/8 h double step homogenization heat treatment can not only eliminate the segregation in the ingot, but also avoid the holes caused by the overburning of the low melting point phases, which makes the billet more conducive to the subsequent billet deformation.

    • Xu Zhenbo, Zhang Tingting, Wang Yan, Bian Gongbo, Wang Tao, Wang Wenxian

      2024,53(1):169-177 DOI: 10.12442/j.issn.1002-185X.20220985

      Abstract:In order to explore the principle of metal composite assisted by high frequency pluse current, the test of rolling-welding magnesium composite plates prefabricated notch assisted by high frequency pulse current is designed.The microstructure evolution and mechanical properties of bonding interface and areas near interface of the composite plates were compared under different loading frequencies (25 kHz, 50 kHz, 75 kHz).The morphological characteristics of microstructures near interface of magnesium alloy composite plates was observed by metallographic microscope;Nanoindentation test and Vickers hardness test were used to characterize the characteristic of the interface micro-region and cross section hardness distribution respectively;The tensile properties and fracture morphology of magnesium alloy composite plates were analyzed by tensile testing machine and electron microscope.The results show that with the increase of the frequency, the composite effect of the interface increases first and then decreases;when the high frequency current parameter is 50 kHz, the tensile strength and elongation of magnesium alloy composite plates are the best, reaching 292.52 MPa and 25.7%, respectively.This can be contributed to the comprehensive role of skin effect、proximity effect、Joule heat effect of current and contact resistance of interface micro-region.

    • Xu Hao, Sun Qianjiang, Wen Chao, Ma Xin, Niu Dongyang

      2024,53(1):178-187 DOI: 10.12442/j.issn.1002-185X.20220977

      Abstract:The quasi-β forging of TC21 titanium alloy was carried out,and then embarked on the solution aging heat treatment experiment,and the effects of different solution aging heat treatment systems on the microstructure and mechanical properties of the alloy.The results showed that after TC21 titanium alloy was forged by quasi-β and treated by solution aging heat treatment process,the microstructure of the alloy presents a typical basket-weave structure.With the increase of solution temperature,the content and length of the lamellar α phase decrease significantly,and the strength of the alloy increase,while the plasticity change showed the opposite trend.With the increase of aging temperature,the effect on the lamellar α phase was slightly smaller,but the thickness of the secondary α phase increases significantly,and the strength of the alloy decreases and the plasticity increases.The morphology of the fracture becomes flatter with the increase of the solution temperature,and the fracture surface and crack growth path become flatter.The fracture toughness value presented a downward trend,but it increased with the increase of aging temperature.The maximum fracture toughness value of the alloy can reach 66MPa·m1/2.Considering the good match between the strength,plasticity and fracture toughness of the alloy,after comprehensive analysis,it can be obtained that the best heat treatment system of TC21 titanium alloy after quasi-β fracture is:870°C/2 h,AC+590°C/4 h,AC.

    • Zhang Qiutao, Liu Shuangyu, Lu Ping, Liu Xueran, Zhang Fulong, Vasilieva Tatiana Mikhailovna

      2024,53(1):188-196 DOI: 10.12442/j.issn.1002-185X.20220802

      Abstract:A new kind TiBN powder material was synthesized by boronizing sintering method. TiBN was both ceramic and metallic, with a resistivity of 2.6 × 10-3 Ω·cm. Cu/TiBN and Cu/TiN electrical contact materials were prepared by powder metallurgy using TiBN and TiN as reinforced phases. These microstructure and physical properties of electrical contact materials with different contents of TiBN and TiN were systematically investigated. The results demonstrated that, when compared to TiN, the TiBN reinforced phase can significantly improve the electrical conductivity, oxidation resistance, hardness, and arc erosion resistance of Cu-based electrical contact materials. When the content of TiBN was 5wt.%, the arc erosion resistance of Cu/TiBN was the best, and the weight loss was only 1.5mg. During arc erosion, products such as TixOy, B2O3 and N2 were formed on the surface of Cu/TiBN. These products can significantly improve the arc erosion resistance of Cu/TiBN electrical contact materials. The newly developed Cu/TiBN electrical contact materials had excellent mechanical properties and resistance to arc erosion, and had a broad application prospect in the electrical contact industry.

    • jiarui, liujianglin, zhangmingze, wangtao, zhengrenhui

      2024,53(1):197-203 DOI: 10.12442/j.issn.1002-185X.20230002

      Abstract:Longitudinal wave rolling + flat roll rolling ( LFR ) is a new rolling process to reduce edge cracks and basal texture of magnesium alloy. This process can prepare magnesium alloy sheets with light edge cracks through one-pass longitudinal wave rolling + two-pass flat rolling. However, the LFR process deformation law is not clear. In this paper, the thermo-mechanical coupling finite element virtual rolling comparison and physical experiments of AZ31 plate longitudinal wave rolling + flat rolling ( LFR ) and flat rolling + flat rolling ( FFR ) were compared, the metal deformation law in the longitudinal wave rolling deformation zone and its influence on the edge damage of the plate were analyzed. The results show that a special-shaped rolling area has formed in the longitudinal wave rolling, which caused shear strain in different parts of the sheet. Furthermore, the temperature drop at the edge of the plate was avoided due to the plastic deformation heat generated by rapid metal flow, which is beneficial to improve the plasticity. The influence of shear strain and temperature promotes the formation of mixed microstructure of LFR sheet, reduces the damage of trough, and effectively inhibits the generation and development of edge crack of magnesium alloy sheet.

    • Wang linlin, houkunlei, Zhaxiangdong, oumeiqiong, mayingche

      2024,53(1):204-214 DOI: 10.12442/j.issn.1002-185X.20230010

      Abstract:The corrosion behavior of four typical Ni-based corrosion-resistant alloys in supercritical aqueous solution of Na3PO4, Na2SO4 and NaCl at 450 ℃/23 MPa was studied by using XRD, SEM, etc. After corrosion for 50 h, the surface of the alloys was covered with short rod-shaped and needle-shaped products mainly consisting of NiCr2O4,Cr2O3,NiO,Ni3(PO4)2,CrPO4 and Na3PO4. With the prolong of time, the thickness of the corrosion layers increased and the corrosion resistance was ranked as X-1#>X-2#>625>C-276

    • Wang Xingxing, Li Yang, Wu shengjin, Du Quanbin, Jia Lianhui, Li Shuai, Chen Xiaoming

      2024,53(1):215-222 DOI: 10.12442/j.issn.1002-185X.20220991

      Abstract:Ni/WC composite coating with high wear resistance, corrosion resistance and high hardness characteristics, it is widely used in shield components, raerospace and other fields. In order to improve the service life of hydraulic machinery overflow components, the paper simulated the material of hydraulic turbine blades, WC particles and Ni-based powder brazing filler metals were used to prepare Ni/WC composite brazing coating on the surface of 201 stainless steel by vacuum brazing process. The interface microstructure and mechanical behavior of the brazing coating were resolved with scanning electron microscope, metallographic microscope and rockwell hardness tester. The results show that the diffusion behavior of elements between the coating and substrate are main dissolution of elements Fe, Cr and Mn from the stainless steel into the coating microstructure, and the interface appears segregation precipitation phenomenon. 25wt.% WC coating occurs a uniform hardness distribution, 4.6 times more than steel substrate. The wear resistance of coating increased with the increase of WC content. 15~35 wt.% WC addition can significantly improve the wear resistance of the steel surface. The wear resistance of the coating is 8.4~15.7times that of the steel, the surface of the coating don’t change significantly, and the crack opening is flat and brittle fracture.

    • heyingjie, maxiangdong, liyuan, xiaolei, yangjinglong, guojianzheng, fenganjiang

      2024,53(1):223-233 DOI: 10.12442/j.issn.1002-185X.20220969

      Abstract:Through a series of hot compression tests on a novel powder metallurgy superalloy FGH4113A (WZ-A3), the effects of deformation temperature, strain rate and strain on the microstructure evolution were investigated. The results demonstrate that when the temperature is 1100 ℃, the strain rate is 0.1 s-1 and the true strain is 0.1~0.7, the increase of strain is beneficial to promote dynamic recrystallization and grain refinement. With the increase of strain, the volume fraction of γ" phase first decreases, then increases, and eventually remains stable. The morphology of γ" phase gradually becomes spherical during the thermal deformation process. Under the conditions of temperature 1100 ℃, deformation 50% and strain rate of 0.01~1 s-1, the increase of strain rate can improve the degree of dynamic recrystallization and refine the grains. With the increase of strain rate from 0.01~0.1 s-1 to 1 s-1, adiabatic temperature rise and dislocation slip intensify, resulting in the volume fraction of γ" phase reduces by about 2%. When the strain rate is 0.1 s-1 and the deformation is 50%, the increase of deformation temperature can promote dynamic recrystallization and grain growth in the temperature range of 1070~1160 ℃. With the deformation temperature rising to 1130 ℃, a large quantity of γ" phase has dissolved, the ability to pin the grain boundary has been significantly weakened, and the average grain size has increased to 12.1 μm. At the deformation temperature of 1100 ℃, strain rate of 1 s-1 and deformation of 50%, fine and uniform “γ+γ′ dual-phase structure " and the grain size above ASTM 12 can be obtained.

    • Yong Zheng, Shaoyu Qiu, Lianfeng Wei, Siliang Yan, Gaozhan Chen, Lifu Yao, Darong Tian

      2024,53(1):234-241 DOI: 10.12442/j.issn.1002-185X.20220954

      Abstract:This work is aimed to investigate time-spatial distribution rules and the effect of process parameters and geometric parameters to the forming quality of CLA16 F/M steel manufactured by electromagnetic incremental forming. Based on LS-Dyna R8.0 platform, an electromagnetic field-structure field sequential coupled finite element-boundary element model of electromagnetic incremental forming process of dummy fuel element was established. With the aid of the numerical simulation model, the electromagnetic forming process of dummy fuel element under different discharging voltages, flyer tube-base tube clearances and wall thickness of flyer tube were simulated and analyzed, and the sample fuel element was manufactured, for the sake of studying the local plastic flow rules, defects generation rules and characterizing the forming quality. Results show that oversized discharging voltage brings about the concentration of deformation zones to both ends of the tube. Also, the collision between the flyer tube and the base tube is aggravated and section distortion is introduced. Undersized discharging voltage can not generate the collision, deformation and sticking and thus leads to disconnection. Appropriate adjusting the clearance between base tube and flyer tube can effectively avoid wrinkling and nonuniformity of wall thickness. By comprehensive optimization of process parameters, through-process high quality precise forming of defects control of dummy fuel element was realized and the sticking precision between base tube and flyer tube reaches 10μm.

    • Cui Jinyan, Yao Jian, He Yingjie, Ma Xiangdong, Xiao Lei, Guo Jianzheng, Feng Ganjiang

      2024,53(1):242-249 DOI: 10.12442/j.issn.1002-185X.20230008

      Abstract:To acquire the boundary of the heat treatment parameters satisfying property boundary is significant for property optimization of powder metallurgy FGH96 turbine disks, especially the boundary of the minimum cooling rate required for FGH96 alloy with a certain grain size under the premise of satisfying the performance requirements. Tensile behavior at 25 ℃, 650 ℃ and 750 ℃ of FGH96 specimens was investigated with different grain size under various cooling rates from solution temperature. The microstructures were observed. The results show that a multi-mechanistic strengthening model including the effect of chemical composition, γ′ size and fraction and grain size agree well with the experimental measurements. The strengthening model was applied to study the minimum cooling rate and grain size. The minimum cooling rate and grain size were obtained as: grain size should be smaller than 14 mm if cooling rates is 55 ℃/min, grain size should be smaller than 16.8 mm if cooling rates is 72 ℃/min, and grain size should be smaller than 20 mm if cooling rates is 81℃/min. The minimum cooling rate and grain size can be used as a guideline to design heat treatment process through simulation.

    • XiaoBo Wang, Li Rong, Hui Huang, Wu Wei, Qian Gao, ZeZhong Wang, Li Zhou, Meng Wang

      2024,53(1):250-256 DOI: 10.12442/j.issn.1002-185X.20220980

      Abstract:In this paper, Al-30Zn-3Cu-2.5Si high Zn Al-based alloy is taken as the research object, the effect of Er and Zr on the microstructure and mechanical properties of as-cast and heat-treated alloys is investigated, and the action mechanism is analyzed and discussed. The results show that the grain size of the alloy can be obviously refined by adding 0.10 wt% Er and 0.10 wt% Zr, the average grain size is reduced from 74.28 μm to 60.01 μm, and the grain size of α-Al is changed into fine equiaxed grains. The addition of rare earth elements Er and Zr can form fine particles of Al3(Er, Zr) in the alloy and pin dislocations to improve the mechanical properties of the alloy. After adding Er and Zr, the tensile strength of as-cast alloy increased from 323.01 MPa of alloys without addition of Er and Zr to 358.29 MPa, and the tensile strength increased by 10.93%; and the yield strength increased from 309.33 MPa to 315.00 MPa, and the yield strength increased by 1.83%; the elongation has not changed basically. The tensile strength and yield strength of the alloy strengthened by solution-aging heat treatment are 449.48 MPa and 408.51 MPa respectively, which are 25.45% and 29.68% higher than those of the as-cast alloy. The coarse second phase exists at the grain boundary, which results in the poor elongation of the alloy.

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    • li leyu, tian fuzheng, li zheng, zhang jingang, deng zhiwei, chen xing, liu xinling

      Available online:December 01, 2023  DOI: 10.12442/j.issn.1002-185X.20230618

      Abstract:In this paper, we investigated the fatigue crack propagation behavior of DD6 nickel-based single-crystal superalloy at test temperatures ranging from 530℃ to 850℃. The fatigue properties were assessed along the [001] direction, parallel to the loading axis in tension. Following the fatigue crack propagation test, the fracture morphology was examined using scanning electron microscopy for classification into one of four zones. These were based on specific morphology characteristics and were as follows: source zone, prefabricated crack zone, stable extension zone, and rapid extension zone. Electron backscatter diffraction was utilized to observe the profiles of plastic deformation perpendicular to the fracture. Additionally, the dislocation process near the fracture was studied using transmission electron microscopy. Our findings show that oxidation occurs at 650℃ under conditions influenced by the temperature field, stress field, and exposure time, and that the γ" phase is also weakened. Furthermore, a significant number of consecutive dislocations form in the γ and γ" phases between 650℃ and 760℃, resulting in increased alloy oxidation and a notable decrease in fatigue resistance and product lifespan..

    • Zhu Wei, Cheng Dazhao, Liu Caiyan, Ma Cong, Wu lu, Zhang Jing

      Available online:December 01, 2023  DOI: 10.12442/j.issn.1002-185X.20230621

      Abstract:The austenite Fe-Cr steels used as the critical in-pile components because of its good high temperature resistance, corrosion resistance and excellent mechanical properties and thermal strength, bear long-period high temperatures and irradiation; the irradiated vacancies aggregate into voids leading to irradiation swelling and hardening, which seriously affects the service safety of the reactor. The phase field method coupling temperature field is employed by solving the phase field equations based the Fourier spectrum method to investigate the voids behavior of austenite Fe-Cr steels upon a central and a one-dimensional temperature field. As the temperature goes down from the center radically in a central temperature field, the vacancies diffuse toward the high-temperature center region driven by the temperature gradient, resulting in the instability of the double voids model, and gradually dissolves to form a new void in the high temperature center region. In the central temperature field, the voids nucleate earlier and grow faster with a sizeable scale in the high temperature than that in the lower temperature region due to the higher vacancy concentration in the central high temperature region. Based on the force-flow relation in the principle of irreversible thermodynamics, the migration behavior of voids upon a one-dimensional temperature gradient is studied by adding advection term to the phase field evolution equation Cahn-Hilliard equation. It has been observed in the experiments that the size of voids in irradiated austenite Fe-Cr steel is nanoscale, and it is generally believed that the nanoscale voids migration is controlled by the bulk diffusion mechanism and surface diffusion mechanism. Therefore, the effects of temperature gradient and initial size of voids on the voids migration upon a one-dimensional temperature gradient in austenite Fe-Cr steel are studied considering both the bulk diffusion mechanism and surface diffusion mechanism respectively. The migration rate governed by the bulk diffusion mechanism positively depends on the temperature gradients but not the initial void"s size. The migration rate governed by the surface diffusion mechanism positively depends on the temperature gradients but is negatively related to the initial void"s size. At the same time, in the process of migration, the shape of the void will also change, and the void will be elongated along the direction of temperature gradient, and the front end is sharper along the direction of temperature gradient, and the back end is wider. The studies inspire the microstructure aging and properties prediction caused by inhomogeneous heat conduct or macroscopic uneven temperature distribution.

    • Wang Yao, Li Jinshan, Chen Bo, Chen Mingju, Chen Biao, Wang Yi, Gong Weijia

      Available online:December 01, 2023  DOI: 10.12442/j.issn.1002-185X.20230625

      Abstract:Accident-tolerant fuel can significantly enhance the capability of light-water nuclear reactors to withstand core melting under LOCA, is a revolutionary development of nuclear fuel technology and nuclear power safety. Cr-coating deposited on the current Zr-based nuclear fuel cladding demonstrates good adhesion, excellent corrosion resistance in high-temperature and high pressure water, and high-temperature oxidation resistance. Therefore, Cr-coated zirconium alloys emerge as the most promising ATF solution for practical engineering application in nearest future. The present paper reviews the research progress on oxidation behavior of Cr-coated zirconium alloy in high-temperature steam environment. The oxidation kinetics of the Cr coating, the effect of microstructure on the anti-oxidation performance of the Cr coating, the failure mechanism of the Cr coating after long-term oxidation and the Cr-Zr interdiffusion behavior are discussed. Additionally, strategies for enhancing the anti-oxidation performance of the Cr coating and suppressing Cr-Zr interdiffusion are summarized, and future development directions are prospected, aiming to provide references for the optimization design and engineering application of Cr-coated Zr-based nuclear fuel cladding.

    • Zhao Yanchun, Song Haizhuan, Ma Huwen, Hu Ruonan, Feng li, Duan Wangchun, Peter K Liaw

      Available online:December 01, 2023  DOI: 10.12442/j.issn.1002-185X.20230636

      Abstract:In this study, (Fe63.3Mn14Si9.1Cr9.8C3.8)99.5-xCuxAg0.5 (x=1, 2, 3, 4, 5 at.%) alloys were prepared using a water-cooled copper crucible magnetic levitation vacuum melting furnace. The effects of different Cu contents on microstructure, the corrosion resistance and antibacterial performance of the alloys were investigated. The results showed that the medium entropy alloys possessed FCC phase after solid solution and aging treatment. With the increase of Cu content, the FCC2 Cu-Ag riched phase precipitated on the FCC1 Fe riched matrix. The corrosion resistance of the alloys in a 3.5% NaCl solution was superior to AISI304. And the corrosion current density first decreased and then increased, and the impedance arc radius first increased and then decreased, indicating an initial enhancement and subsequent weakening of the corrosion resistance as the Cu element adding. Moreover, the corrosion rate of the alloys in Escherichia coli suspension shows a trend of first increasing and then decreasing. Among them, the x=2 alloy exhibited the best corrosion resistance. And there is a trade-off effect between the corrosion resistance and antibacterial performance. The FCC2 phase effectively enhances the antibacterial performance of the alloy, whereas the antibacterial rate of the x=5 alloy reaches 99.93%.

    • Niu Yong, Jia Yunjie, WANG Yaoqi, Zhu Yanchun, Zhang Zongyuan

      Available online:December 01, 2023  DOI: 10.12442/j.issn.1002-185X.20230646

      Abstract:In this study, the deformation mechanism of single-crystal titanium was investigated by molecular dynamics simulation, the temperature was 500~1000K, the strain rate was "0.0001" 〖"ps" 〗^"-1" ~"0.01" 〖"ps" 〗^"-1" , and the loading mode was tensile and compressive, and the results were subjected to the stress-strain analysis, potential analysis, coevolutionary neighbourhood analysis and dislocation density analysis. The results show that with the increase of temperature, the yield strength decreases, and the strain value corresponding to the yield point decreases; at the same temperature, the tensile yield strength is slightly higher than the compressive yield strength; the modulus of elasticity does not change much under different loading rates, and the yield strength increases with the increase of loading rate. With the increase of temperature or loading rate, the peak potential energy of the system increases. As the strain proceeds, the HCP structure decreases, the Other structure increases, and the BCC and FCC structures appear and increase (except at the deformation temperature of 1000K); after exceeding the yield point, the various structures gradually tend to stabilise; with the increase of temperature, the transformation of crystal structure occurs earlier. The dislocation density decreases with increasing temperature, and the total dislocation density under tensile load is larger than that under compressive load; The main types of dislocations throughout the deformation process are Other dislocations, 1/3<-1100>dislocations and 1/3<11-20> dislocations.

    • Shang Xiaofeng, Sun Chen, Zhao Yuhui, He Chen, Zhao Jibin

      Available online:December 01, 2023  DOI: 10.12442/j.issn.1002-185X.20230667

      Abstract:Objective To solve the connection problem of TC4-7075 heteroalloy with large differences in physical parameters, and to expand the application range of high specific strength titanium-aluminum heteroalloy composite structure. Methods AlTiVNbSi high-entropy alloy was selected as the intermediate layer material, and the effective connection of TC4 and AA7075 heteroalloys was realized by laser melting deposition technology, and the macromorphology, microstructure, component distribution and interface characteristics of the junction area were characterized by metallographic microscopy (OM), scanning electron microscopy (SEM, EBSD), microhardness and tensile experiment. Results The connection joint is well combined with the TC4 titanium alloy side interface, and there is an interface transition zone with a width of about 20μm, TC4 near the interface has bundled Weisler tissue, and a compound area with a width of 20μm exists at the 7075 side interface. Conclusion Based on AlTiVNbSi as the intermediate layer material of high-entropy alloy, laser melting deposition technology can realize the effective connection of titanium-aluminum heteroalloy, the hardness of the joint is about 696HV, which is higher than the hardness of the base metal, the hardness of the connecting zone on the near titanium side is higher than that of the connecting zone on the aluminum side, and the tensile strength is 116MPa.

    • Li Huizhao, Liang Kaiming, Pan Rui, Wang Caimei, Zhu Xiaoteng, Hu Zhenggen, Zhang Hua

      Available online:December 01, 2023  DOI: 10.12442/j.issn.1002-185X.E20230026

      Abstract:This research study employed self-designed induction coils, rigid restraint kits, and the existing laboratory induction heating apparatus to conduct a local induction heating-based rigid restraint thermal self-compressing bonding (TSCB) treatment on a 5 mm-thick TC4 titanium alloy plate (the base metal). The objective was to investigate the influence of holding temperature and heat treatment on the microstructure and mechanical properties of the joint. The results demonstrate that excessively low holding temperatures (900°C) result in insufficient atomic diffusion, while excessively high holding temperatures (990°C) exceeding the β to α phase transformation temperature lead to the formation of coarse widmanstatten microstructures, both of which contribute to a decrease in the mechanical properties of the joint. As the temperature increases, the pressure applied to the joint by the thermal constraint stress field initially rises and subsequently declines, accompanied by a corresponding trend in the quality of the joint connection. Optimal mechanical properties were achieved only when the holding temperature was slightly below the β to α phase transformation temperature, specifically at 950°C. At this temperature, the microstructure distribution exhibited the highest level of uniformity, characterized by a significant presence of equiaxed α-phase grains. Additionally, the atomic diffusion was sufficiently enhanced, coupled with the highest pressure exerted on the joint by the stress field, resulting in the attainment of optimal mechanical performance. Upon annealing heat treatment at 650℃/3h, the α→β phase transformation was observed, accompanied by a reduction in the degree of lattice distortion and grain refinement. The residual stress state of the TSCB joint was transitioned from tensile stress to compressive stress. The residual stress was significantly reduced, leading to stress relief. Consequently, the mechanical properties of the TSCB joint were improved, addressing the issue of low plasticity in the TSCB joint.

    • wang huigai, zhang keke, wang bingying, wang yaoli

      Available online:December 01, 2023  DOI: 10.12442/j.issn.1002-185X.E20230029

      Abstract:Sn2.5Ag0.7Cu0.1RE0.05Ni lead-free solder alloy taken as the research object and Ni-modified GNSs (Ni-GNSs) as the reinforcement phase, Ni-GNSs reinforced Sn2.5Ag0.7Cu0.1RE composite solder was made using mechanical alloying. The soldering test of composite solder/Cu and the thermal aging test of soldering joints were carried out to investigate the effect of Ni-GNSs on the microstructure and thermal aging fracture mechanism of composite soldering joints. The results showed that addition of Ni-GNSs inhibited the linear expansion of the composite solder, resulting in lattice distortion and dislocation. The intermetallic compounds (IMC) particles near the dislocation line interacted with the dislocation and hindered its movement, then the composite solder was strengthened. Druing the thermal aging process of this study, the thickness of interfacial IMC layer increased and the shear strength of soldering joints decreased. Among them, the shear strength of the composite soldering joints with 0.05wt.% GNSs addition decreased the least, only 8.9%. Moreover, after 384 h of thermal aging, its shear strength was still higher than that of the Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu soldering joints before aging. With the addition of Ni-GNSs, the growth coefficient of interfacial IMC of composite soldering joints was significantly reduced, which effectively alleviated the decrease of mechanical properties of composite soldering joints during the thermal aging process, and then changed the thermal aging fracture mechanism of composite solder/Cu soldering joints, and ultimately affected the reliability of joints. The fracture position of the Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu soldering joints moved from the soldering seam before thermal aging to the soldering seam/interfacial IMC, which was ductile-brittle mixed fracture. The fracture position of the Sn2.5Ag0.7Cu0.1RE0.05Ni-0.05GNSs/Cu soldering joints was all in the soldering seam zone, which was ductile fracture and the reliability of the joints was high.

    • LU Guoxin, LUO Xuekun, WANG Qiang, LIU Jide, WANG Xin, ZHANG Yongkang, LI Jinguo, LU Feng

      Available online:November 28, 2023  DOI: 10.12442/j.issn.1002-185X.20230616

      Abstract:With the further improvement of material fatigue life extension and processing of parts with complex shapes, laser shock processing has encountered more and more obstacles in practical applications and it is particularly urgent to improve and optimize the specific processing methods in laser shock treatments. Using the stress effect produced by pulsed lasers to process materials in various fields still has broad prospects. Given the specific needs of laser shock in different industrial applications, several processing improvement methods which get rid of the equipment dependence on high-performance laser units were proposed. The non-laser parameters referred to include adjustable indicators such as the absorption layer, constraint layer, and defocusing state between laser and material. The selected material, thickness, and other related attributes of the absorption layer and the constraint layer directly affect the intensity of laser-induced shock waves, while changes in defocusing amount lead to differences in physical or chemical effects on the material surface. The process setting range for the above non-laser indicators is wide and easy to control, and reflects good adaptability of irregular components. The development of new technologies for equal (unequal)-strength and high-strength surface strengthening based on changes in these indicators, as well as new green packaging technologies such as laser marking, are introduced in detail. The new ideas behind these new methods are expected to inspire researchers to further explore the application potential of green lasers.

    • zhangwei, chengdazhao, liucaiyan, macong, wulu, zhangjing

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230525

      Abstract:Nuclear materials are exposed to high temperature, high pressure and strong irradiation for a long time, and are subjected to strong neutron irradiation, which will produce a large number of point defects under the action of cascade collision, and then form radiation voids. Irradiation swelling caused by irradiation voids is responsible for the failure of austenite steel serve in the reactor core. The external stress introduced in the process of material processing and service and the elastic stress field generated by crystal defects such as dislocation have an important influence on diffusion and phase transformation. The phase field method at mesoscale can not only couple the physical fields such as temperature, irradiation and stress, but also simulate the dynamics and morphology evolution of the microstructure of materials during irradiation. A mesoscale phase field model coupled with rate and micro-elastic theory is used to survey the stress effects on void microstructures for Fe-Cr austenite; the global applied stress and the local dislocation stress field are considered. The applied stress promotes vacancies aggregate, nucleate, and growth, and the voids evolve into fusiform eventually. Voids in the stressed state have a larger size and lower density compared with a stress-free state. The larger the applied stress, the larger the average size and volume fraction, the smaller the number, and the more significant the morphology reconstruction is. The local elastic stress field of dislocation absorbs vacancies to reduce the elastic energy, and the concentrated vacancies accelerate the voids preferentially nucleate and grow around the dislocation. Compared with the dislocation-free system, the voids are fine and denser when dislocations exist; but the volume fraction and the morphologies of voids persist. In contrast, the applied stress should probably cause server swelling than dislocations in Fe-Cr alloys. The studying benefits the properties evaluation of in-core reactor components.

    • Wang Rongshan, Jia Xingna, Zhou Qian, Zhang Yanwei, Bai Guanghai, Xu Chi, Xue Wenbin

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230531

      Abstract:Zirconium alloys are used as fuel cladding materials in commercial reactors, which suffer from synergetic effects of irradiation and corrosion degradations. In order to evaluate the effects of irradiation on the corrosion behavior of the Zr-1Nb alloy, the alloy has been irradiated with 6.37 MeV Xe ions. The pre- and post-irradiation corrosion property modifications have been evaluated. The current paper have also reported the micro-hardness, surface roughness and phase composition modifications. After the Xe ion irradiation, unraveling surface has been observed due to the ion sputtering effect. The surface roughness and the microhardness are increased with increasing irradiation dose. The post-irradiation corrosion under LiOH solution result with lath shaped surface microstructures on the Zr-1Nb samples, which become more pronounced at higher irradiation doses. The polarization current density for the 0.5 dpa dose irradiated sample is increased by 18 times over that of the unirradiated sample, while it is about 72 times for the 2.7 dpa irradiated sample. After the ion irradiation tests, the polarization potentials are lowered (increased negatively) and the polarization resistance values are increased, compared with the unirradiated sample. The electro-chemical impedance spectra (EIS) results show that, the lower-frequency impedance values are decreased, the curvature radius of the capacitance curve is decreased and the phase angle peak is moving rightward with increasing irradiation doses. The polarization curves and the EIS results show that the ion-irradiation has increased the corrosion tendency of the Zr-1Nb alloy, and its corrosion resistance is decreased with increasing irradiation doses. The reduced corrosion resistance after the ion irradiation tests are considered to be mainly caused by the irradiation induced damages on the alloy matrix material.

    • He miaoxia, Yan Chi, Dong Yuecheng, Chang Hui, Alexandrov I.V

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230547

      Abstract:The effects of Mn microalloying on the microstructure and mechanical properties of a new near-α Ti-Al-Mo-Zr-Fe-B alloy were studied by OM, EBSD and TEM. The results indicated that the addition of 0.5wt.%Mn element can refine the casting microstructure of the alloy from 3.28μm to 2.65μm, which led to the tensile strength increase from 882MPa to 966MPa, however, the elongation to failure decreased from 7.8% to 5.1%. After forging, the grain size of two alloys tended to be similar, but the microstructure is more equiaxed and homogenious with the Mn microalloying. Compared with the tensile strength and elongation to failure of Ti-Al-Mo-Zr-Fe-B alloy increased to 966MPa and 16.4%, the alloy containing 0.5wt.% Mn element possessed higher tensile strength to 1079MPa, meanwhile, the elongation to failure retained to 15.7%. The increase of strength can be attributed to the solid solution strengthening effect of Mn element. At the same time, the Mn microalloying enriched the Al element to the α phase in the alloy, which is beneficial to improve the strength and plasticity of the alloy.

    • Shi Qianshuang, Bai Run, Hua Xingjiang, Li Shilei, Hu Boliang, Zhang Wen, Hu Ping

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230551

      Abstract:Low-density niobium alloys have characteristics such as low density, high melting point, and good corrosion resistance, and are widely used in aerospace, nuclear engineering, high-temperature structures, and other fields. To study the effect of different deformation processes on the microstructure and properties of low-density niobium alloys, rolling and extrusion deformations were carried out on the low-density niobium alloys in this study, and the effects were investigated through OM, SEM observation, mechanical property testing, and other methods. The results indicate that when rolling deformation is used, the deformation is large, the microstructure is uniform, the second phase is dispersed, the strength is high, and the plasticity is good, with an elongation after fracture of up to 37 %. When extrusion deformation is used, stress concentration can easily lead to cracking, and deformation is not easy to penetrate. The microstructure is not uniform, and the strength is high, but the plasticity is only 15 %, the impact of deformed microstructure on mechanical properties has been analyzed, which can guide the processing of niobium alloys.

    • XU Hanyuan, HUANG Taiwen, AI Cheng, MIAO Linkun, ZHANG Jun, LIU Lin

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230568

      Abstract:With outstanding comprehensive performance at high temperature, Nickel-based single crystal superalloy is the preferred material for aero-engine turbine blades, vanes and other components to withstand challenging service environment subjected to high temperature and intense stress. At present, various complex cooling structures are often used in the design of high-efficiency cooling blades to enhance blade temperature tolerance, among which the micro-cooling structure represented by lamilloy and double wall cooling are the main trend. However, the existence of ultra-thin wall structures in these complex turbine blades has become critical aspect and challenge in blade manufacturing. This paper provided an overview of the development trends in thin-walled structure of Ni-based single-crystal superalloys, analyzed the defects arising from thin-walled constrained space and the law of dendrite growth, elaborated the influence of thin-walled structure on mechanical properties and provided a prospect on advanced turbine blades preparation and development trend of its microstructure regulation.

    • Feng Li, Wang Zhipeng, Zhao Yanchun, Bian Chunhua

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230570

      Abstract:In this study, FeCrMnxAlCu (x = 0, 0.5, 1.0, 1.5, 2.0) high-entropy alloys were prepared using a vacuum arc melting furnace. The microstructure and chemical composition of the alloys were analyzed using equipment such as XRD, SEM, and EDS. Additionally, the corrosion resistance of the alloys in 3.5 wt.% NaCl solution was evaluated through electrochemical polarization curve tests and immersion experiments. After corrosion, the alloy surfaces were analyzed using XPS equipment.The results of microstructure characterization showed that the prepared high-entropy alloys exhibited typical dendritic and interdendritic structures and possessed a dual-phase structure of FCC and BCC . Corrosion test results indicated that the corrosion resistance of the high-entropy alloys increased initially and then decreased with an increase in Mn content. However, compared to the alloy without Mn, alloys containing Mn still exhibited better corrosion resistance. Among them, the FeCrMnAlCu high-entropy alloy demonstrated the best corrosion resistance, with a more positive corrosion potential (Ecorr = -0.417 V) and a smaller corrosion current density (Icorr = 2.120×10-6 A?cm-2). Furthermore, the FeCrMnxAlCu high-entropy alloys activated and formed discontinuous and loose corrosion product films.

    • Feng Li, Wang Zhaoqin, Zhao Yanchun, Zhang Wei

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230572

      Abstract:This study employs vacuum arc melting technology to fabricate FexCrMnAlCu (x=0, 0.5, 1, 1.5, 2) high-entropy alloys. The phase structure and microstructure of the alloys before and after corrosion were characterized using XRD, SEM, and EDS. The corrosion behavior and oxide film composition of the alloys in a 3.5% NaCl solution were investigated through potentiodynamic polarization curves, EIS, XPS, and immersion tests. The results indicate that FexCrMnAlCu high-entropy alloys exhibit a dual-phase structure of BCC+FCC. The addition of Fe enhances the intensity of the BCC phase diffraction peaks. As the Fe content increases, the alloy"s corrosion resistance initially improves and then deteriorates. Alloys with added Fe exhibit superior corrosion resistance compared to those without Fe. This is attributed to the change in grain size caused by the addition of Fe, which alters the number of grain boundaries per unit area, consequently affecting the corrosion resistance. The primary type of corrosion observed in FexCrMnAlCu alloys is intergranular corrosion. After corrosion, an oxide film composed of various elemental oxides forms on the alloy surface. The Fe1.5CrMnAlCu alloy exhibits the lowest self-corrosion current density (1.75×10-6 A/cm2), the most positive self-corrosion potential (-0.589 V), and the largest impedance arc radius.

    • zhaomeng, zhouhui, heyanchun, guibinhua, wangkeliang

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230575

      Abstract:TiN coatings are widely used in metal bipolar plate modification due to good corrosion resistance and electrical conductivity.The TiN deposition process is susceptible to formation non-metallic vacancies due to the preparation conditions, affecting the coating properties. Therefore, in this paper, the electronic structures of TiNx systems containing different amounts of nonmetallic vacancies are calculated using the first principle method, and a study of the effect of nonmetallic vacancies on the crystal structure, energy band structure, density of states, relative concentration of free electrons, and charge spreading of each TiNx system is carried out. The analytical results show that with the formation of nonmetallic vacancies, the stability of each TiNx system gradually decreases and the nonmetallic vacancy formation energy gradually increases. The relative concentration of free electrons of each TiNx system is calculated to be in the following order: TiN0.25>TiN>TiN0.5>TiN0.75.The electrical conductivity of the TiNx system is mainly affected by the combination of three factors: the metallization of the 3d orbital state of the Ti atoms, the reduction of the contribution of the N atoms to the 2p orbitals, and the decrease in the volume of the crystal cell due to the deletion of the N atoms.

    • Yu Yang, Geng Chen, Hui Li, Jinglong Liang, Meilong Hu, Mengjun Hu

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230580

      Abstract:High-entropy carbides (HECs) are materials with great potential as catalysts for the hydrogen evolution reaction (HER), but the production of nanoscale HECs remains a significant challenge. This study successfully prepared nanoscale (VNbTaZrHf)C HEC powders with a face-centered cubic (FCC) structure by electro-deoxidation of metal oxides and graphite in CaCl2 at 1173 K. The appropriate temperature conditions were favorable for suppressing the in-situ sintering growth of HEC particles. Electrochemical performance testing was carried out in 1M KOH to explore the catalytic performance of the (VNbTaZrHf)C HEC. The catalytic HER performance of (VNbTaZrHf)C HEC was evaluated through polarization curves, Tafel slope, electrochemical impedance spectroscopy, and double-layer capacitance value CV testing. The double layer capacitance value of (VZrHfNbTa)C is 40.6 mF/cm2. The larger double-layer capacitance value indicated a larger electrochemically active surface area. Due to the high-entropy effect and nanoscale structure of (VNbTaZrHf)C HEC, it exhibits superior catalytic HER performance and develops a novel method for the preparation of HECs via molten salt electro-deoxidation.

    • Zhang Wenbin, Yang Haijuan, Liu Cuirong, Li Yan, Shi Aizun

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230600

      Abstract:To save the cost of using nickel materials and fully utilize their excellent corrosion resistance, pure nickel N6 with a thickness of 1mm was selected as the flyer plate and medium carbon steel 45# with a thickness of 3mm was used as the base plate for explosive welding tests. The dynamic parameters were calculated through the explosive welding window, and the interface bonding morphology and elements were analyzed using metallographic microscopy (OM) and scanning electron microscopy (SEM). The mechanical properties of the composite plate were tested through shear tests, and the explosive welding process was simulated using AUTODYN. The results indicate that there is a "boundary effect" near the explosion point, and the bonding interface along the explosion welding direction changes from a straight shape to a stable wavy interface. The thickness of the element diffusion layer near the interface is 20um, and the wavy diffusion layer increases the bonding area, which is conducive to metallurgical bonding. The shear strength of the composite plate reaches 325.5Mpa. Analyzing the numerical simulation results, it was found that the interface morphology was consistent with the experimental results. The simulation results showed that the velocity and plastic deformation degree of the characteristic points were also consistent with the experimental results.

    • Xia Penghui, Wang Weiqiang, Shi Shuyan, Lu Chao, Cao Tieshan, Min Xiaohua

      Available online:November 22, 2023  DOI: 10.12442/j.issn.1002-185X.20230346

      Abstract:Based on DD98M nickel-based superalloy, four kinds of alloys of A1-Ta /(Ta+Ti)=0, A2-Ta /(Ta+Ti)=0.34, A3-Ta /(Ta+Ti)=0.66 and A4-Ta /(Ta+Ti)=1 were prepared by vacuum induction melting, keeping the total amount of γ" phase forming elements of (Ta+Ti) in the alloys unchanged. The as-cast alloys were subjected to solution aging and long-term aging at 1273k. X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe (EPMA) were used to study the microstructure of the four alloys after aging. The effects of long-term aging at a high temperature and the change of Ta/(Ta+Ti) on the as-cast microstructure and properties of the alloys were analyzed. The results show that long-term aging causes partial decomposition of γ" phase, promotes element diffusion and intensifies element segregation. With the extension of long-term aging time, the γ" phase coarsens, the hardness decreases, the absolute value of misfit decreases, and the cubic degree of γ" phase decreases. With the increasing proportion of Ta in (Ta+Ti), the absolute value of misfit decreases, the cubic degree of γ" phase decreases, and the hardness increases. Under the long-term aging condition, the segregation of Cr, Mo, W and Ta is intensified, and the segregation of Ti is alleviated. The addition of Ta will squeeze W into the γ phase. After long-term aging, σ phase and MC carbide precipitated at the grain boundaries of A2 and A3 alloys, while no precipitation was observed at the grain boundaries of A1 and A4 alloys, indicating that the synergistic effect of Ta and Ti promotes the precipitation of σ phase and MC carbide. A2 alloys have relatively high γ" phase volume fraction, γ" phase cubed degree, hardness and strength, the smallest γ" phase size and the highest elongation, so A2 alloys have the best comprehensive mechanical properties of the four alloys.

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    Latest number
    Rare Metal Materials and Engineering
    2024,Volume 53, Issue 1
    Editor in chiefPingxiang Zhang
    Associate editorYingjiang Shi
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