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Wu Qingjie, Guo Zhenghua, Huang Qin, Lingli Shibao
2024,53(11):3017-3025 DOI: 10.12442/j.issn.1002-185X.20240073
Abstract:High-entropy alloy (HEA), as a class of new alloy materials characterized by high stability, excellent specific strength and corrosion resistance, has attracted much attention in the field of aluminum matrix composites (AMCs). To study the effect on microstructure and mechanical properties of aluminum alloys, AlCoCrFeNi HEA particles reinforced ADC12 composites were fabricated by high energy ultrasonic casting process. Subsequently, the effect of HEAs addition on the microstructure and mechanical properties of ADC12 alloys was investigated. Results show that the added HEA particles are tightly bonded to the aluminum matrix. The Al2Cu phase in the matrix is refined. Meanwhile, the tensile strength and microhardness of the alloys with the addition of HEA particles are significantly improved. The yield strength and ultimate tensile strength of as-prepared composites with 12wt% HEAs are increased by 16.9% and 21.9% compared with those of the matrix, respectively. The wear rate of the composites is also decreased due to the enhancement of microhardness under applied load of 20 N. It is mainly attributed to the load transfer strengthening, dislocation proliferation and the optimization of the microstructure.
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Feng Li, Wang Zhipeng, Zhao Yanchun, Bian Chunhua
2024,53(11):3175-3184 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.
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Qin Xu, Qi Wang, Jiading Zhao, Yajun Yin, Ruirun Chen
2024,53(11):3194-3204 DOI: 10.12442/j.issn.1002-185X.20230581
Abstract:CrMoNbTiVx (x=0, 0.2, 0.4, 0.6, 0.8) refractory high entropy alloys with different addition of vanadium were prepared, and the phase constitution, microstructure characteristics and oxidation properties at elevated temperature were investigated. Results show that the as-cast CrMoNbTiVx alloys with different addition of vanadium exhibit single body-centered cubic (BCC) crystal and form dendrite structure. After oxidation at 800 ℃ for 20 h and 100 h, weight gains of CrMoNbTi alloy are 0.25 mg/cm2 and 0.50 mg/cm2, respectively, while weight gains of CrMoNbTiV0.8 alloy are 1.49 mg/cm2 and 3.36 mg/cm2, respectively. Weight gains of CrMoNbTiVx alloys are decreased with decreasing of vanadium, and the surface of oxidation layer gets smoother with decreasing of vanadium. Height differences of CrMoNbTiV0.8 and CrMoNbTi after oxidation for 100h are 24.80 μm and 3.37 μm, respectively. The oxidation products of alloys with different addition of vanadium are different, and the V2Nb6O19 needle shape oxidation products can obviously reduce the oxidation properties of CrMoNbTiVx alloys. Reducing the addition of vanadium can promote formation of compact oxidation products of TiO2, CrVNbO6 and Ti4Cr3Nb3O2, and therefore improve oxidation properties of CrMoNbTiVx alloys. V2Nb6O19, CrVNbO6 and V2O5 in oxidation layer of CrMoNbTiVx alloys are reduced with decreasing of vanadium. The oxidation layer of CrMoNbTi without addition of vanadium is consisted of compact TiO2 and Ti4Cr3Nb3O2, and therefore the oxidation resistance is significantly improved.
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wang yanfang, He Yaru, Hu Fangyu, Shi Zhiqiang
2024,53(11):3224-3232 DOI: 10.12442/j.issn.1002-185X.20230588
Abstract:High-entropy bulk metallic glasses (HE-BMGs) are novel bulk alloys combined the multi-principal component characteristics of high-entropy alloys with the long-range disordered atomic stacking characteristics of metallic glass. HE-BMGs, like conventional BMGs, are thermodynamically in a metastable state. However, the crystallization processing of HE-BMGs is different from the conventional BMGs. In this paper, non-equiatomic ZrxTiNiCuBe (x=1.5, 2, 2.5, 3, 3.5at.%) HE-BMGs are prepared by copper mold casting method, and their crystallization kinetics was studied by differential scanning calorimeter (DSC) under both non-isochronal and isothermal conditions. The non-isothermal crystallization kinetics of Zrx HE-BMGs showed a multiple-stage processing. The characteristic temperatures increased with the increase of the heating rate, showing obvious kinetics effects. The activation energy calculated by the Kissinger equation showed Eg>Ex>Ep1,indicating that the overcoming the energy barrier for the rearrangement of was more difficult than atoms nucleation process and the grain growth process of crystallization. The activation energy of crystallization event is Ep1
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Song Bo, Xi Honglei, Fu Yu, Wang Junshuai, Xiao Wenlong, Ren Yanbiao, Ma Chaoli
2024,53(11):3001-3009 DOI: 10.12442/j.issn.1002-185X.20240111
Abstract:The influence of pre-deformation on phase transformations, microstructures and hardening response in near β Ti alloy Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe (wt%) during aging treatment was studied. The results show that obvious α phase refinement and stronger age hardening effect can be achieved when the alloy is slightly deformed before aging treatment. Because the formation of intermediate phases (O′, ω and O′′) suppresses long-range stress induced martensitic transformation and mechanical twinning, the alloy is mainly deformed via dislocation slipping during loading. Large numbers of crystal defects are generated during pre-deformation. With increasing the pre-deformation, the number density of dislocations increases gradually. These crystal defects generated by pre-deformation may partly annihilate upon early aging, but the precipitation of α can also be promoted, resulting in refined α precipitates. In the sample with 5% pre-strain, the average thickness of α precipitates decreases by 57% after aging at 600 °C compared with the sample without pre-strain, and the number density increases from 7.0±1 laths/μm2 to 22.0±3 laths/μm2. Some platelet-shaped α phases form when the samples experience comparably large pre-strains such as 12% and 20%. It proves that the refined α precipitates and better hardening effect can be achieved by pre-deformation plus aging treatment for titanium alloy.
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Yao Zhifeng, Qiao Jichao, Jean-Marc Pelletier, Yao Yao
2024,53(11):3010-3016 DOI: 10.12442/j.issn.1002-185X.20240083
Abstract:Three-point bending fatigue experiments were conducted on a typical Zr-based bulk metallic glass (BMG) at ambient temperature to investigate the fatigue behavior under cyclic loading conditions. Results show that the stress amplitude-cycles to failure (S-N) curve of the Zr-based BMG is determined, and the fatigue endurance limit is 442 MPa (stress amplitude). To evaluate the probability-stress amplitude-cycles to failure (P-S-N) curve, an estimation method based on maximum likelihood was proposed, which relies on statistical principles to estimate the fatigue life of the material and allows for a reduction in the number of samples required, offering a cost-effective and efficient alternative to traditional testing methods. The experimental results align with the American Society for Testing and Materials (ASTM) standard, indicating the reliability and accuracy of this estimation method in evaluating the fatigue behavior of Zr-based BMG.
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Liu Haitao, Wang Lei, Zhao Zhenlong, Wang Linxin, Tang Yongkai
2024,53(11):3026-3034 DOI: 10.12442/j.issn.1002-185X.20240078
Abstract:Machine learning prediction models for thin wire-based metal additive manufacturing (MAM) process were proposed, aiming at the complex relationship between the process parameters and the geometric characteristics of single track of the deposition layer and surface roughness. The effects of laser power, wire feeding speed and scanning speed on the width and height of the single track and surface roughness were experimentally studied. The results show that laser power has a significant impact on the width of the single track but little effect on the height. As the wire feeding speed increases, the width and height of the single track increase, especially the height. The faster the scanning speed, the smaller the width of the single track, while the height does not change much. Then, support vector regression (SVR) and artificial neural network (ANN) regression methods were employed to set up prediction models. The SVR and ANN regression models perform well in predicting the width, with a smaller root mean square error and a higher correlation coefficient R2. Compared with the ANN model, the SVR model performs better both in predicting geometric characteristics of single track and surface roughness. Multi-layer thin-walled parts were manufactured to verify the accuracy of the models.
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Wang Wenqin, Chen Jigen, Yan Xiaosong, Han Zhaoxian, Lin Gang, Chen Jie
2024,53(11):3035-3045 DOI: 10.12442/j.issn.1002-185X.20240020
Abstract:SiC particle (SiCp)/Al composite materials were fabricated via powder packed resistance seam welding additive manufacturing. The influence of welding speed on microstructure and mechanical properties of the specimen was investigated, elucidating the formation and fracture mechanism of single-pass multi-layer deposition. The results demonstrate that a dense internal structure of the specimen characterized by uniformly dispersed SiCp embedded within the Al matrix is formed. However, particle agglomeration and porosity defects are observed. The porosity increases with the increase in welding speed, and the microstructure of the RSAM-24 specimen has the highest density, characterized by a density of 2.706 g/cm3 and a porosity of 1.672%. The mechanical properties of the specimens decrease as the welding speed increases. Optimal mechanical properties are obtained when the welding speed is set as 24 cm/min. Specifically, the average hardness, tensile strength and elongation values are 463.736 MPa, 52.16 MPa and 2.2%, respectively. The tensile specimens predominantly exhibit fracture along the interlayer bonding interface and the interface between the Al matrix and SiC particles, and the damage mode is ductile fracture.
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Zhang Jiqiang, Jin Lei, Luo Jiangshan, Luo Bingchi, Wu Weidong
2024,53(11):3046-3052 DOI: 10.12442/j.issn.1002-185X.20240042
Abstract:The local structure and dynamics of impurities Fe, Al and Mn in beryllium were investigated on an atomic scale using ab initio molecular dynamics and statistical physics methods. The analysis of the radial distribution function centered on impurity atoms shows that the density of beryllium atoms around Fe and Mn is 8.4% and 8.6% higher than that around Al, respectively. The statistics of the measure square displacement of impurity atoms show that the diffusion coefficients of Al atoms are 114% and 133% larger than that of Fe and Mn atoms in the melt beryllium, respectively. Statistical analysis of velocity autocorrelation function of impurity atom shows that Fe and Mn atoms collide strongly with beryllium atoms in the first coordination layer, indicating that they are tightly surrounded and bound by the surrounding beryllium atoms in the central position, while the beryllium atoms around Al are loosely arranged and have weak binding forces with Al. The analysis of the activity coefficients of the impurities shows that when Fe or Mn enters the melt beryllium, it reduces the free energy of the system, whereas when Al enters, it increases the system energy. In summary, the interatomic force of BeAl is weak, so they do not form intermetallic compounds, and Al diffuses quickly in beryllium. While BeFe and BeMn have strong interatomic forces, and tend to form more BeFe and BeMn bonds to reduce the free energy of the system, so Fe and Mn diffuse slowly in beryllium. Ab initio molecular dynamics can be used to forecast the best experimental temperature for the vacuum distillation of beryllium.
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Luo Jiajun, Quan Ciwang, Zhang Jianjun, Chen Shuixiang, Zhang Xitong, Han Mengyao, Liang Bingliang, Chen Weihua
2024,53(11):3053-3063 DOI: 10.12442/j.issn.1002-185X.20240105
Abstract:Core-shell MoSi2@Nb powder was prepared by electrostatic layer self-assembly method. The surfactants SDS (CHSO4Na) and CTAB (C19H42BrN) were used to modify the surface of the two particles to make them charged, and the Zeta potential of the suspension was tested by the Zeta potentiometer. Scanning electron microscope, transmission electron microscope and energy dispersive spectrometer were used to characterize the phase, morphology, microstructure and element distribution of synthetic materials. The results show that when the SDS concentration is 2 mmol/L, the CTAB concentration is 3mmol/L and the pH value of Nb suspension is 5, the coating effect is better after secondary cladding. NbSi2 phase is found at the interface between Nb and MoSi2 after calcination at 200 °C for 2 h in Ar atmosphere, indicating that Nb is highly active and reacts with Si. Core-shell structure is still retained in MoSi2@Nb material after spark plasma sintering at 1450 °C for 2 h under uniaxial pressure of 40 MPa. However, it is found that Nb reacts strongly with MoSi2, and most of the Nb phase is reacted. This issue needs to be addressed in subsequent studies. The fracture toughness (KIC) of MoSi2@Nb material is significantly improved to 5.75 MPa·m0.5 compared with that of MoSi2 material (3.32 MPa·m0.5).
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Li Yi, Wang Jincheng, Ni Juan, Shen Shaobo
2024,53(11):3064-3076 DOI: 10.12442/j.issn.1002-185X.20240163
Abstract:The production of deep well-shaped WC-Co cemented carbide blocks via industrial powder pressing remains a challenging technical problem, primarily due to the unsuitability of the forming agent. The forming agent paraffin wax was modified through four types of modifiers, including organic high-molecular-mass resins, plasticizers, surfactants and lubricants. The qualitative screening of resin types was explored and an orthogonal experiment involving the combination of these four paraffin wax modifiers was conducted to obtain an optimized quantitative ratio of modifiers. The results reveal that the insertion of the small molecule chain of resin into the interstitial spaces of paraffin wax crystals is likely a crucial factor for improving the compatibility between the resin and paraffin wax. Through orthogonal experiments, the optimized formulation for the forming agent is determined: 100 parts of 58# paraffin wax, 15 parts of EVA-2, 4 parts of DPHP, 4 parts of oleic acid amide and 2 parts of stearic acid. This optimized formulation is applied to industrial production at one Chinese company, and qualified deep well-shaped cemented carbide products are achieved, which contain 90wt% WC and 10wt% Co.
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Sun Yuling, Liang Hanliang, Zhu Jiansheng, Ma Honghao, Wang Luqing, Zhang Bingyuan, Luo Ning, Shen Zhaowu
2024,53(11):3077-3083 DOI: 10.12442/j.issn.1002-185X.20240103
Abstract:Explosion welding was carried out on the basis of vacuum hot melt W/CuCrZr composite plate. Metallurgical microscope, scanning electron microscope and energy dispersive X-ray spectroscope were used to observe the microscopic morphology of the bonding interface. At the same time, combined with finite element calculations, the evolution mechanism of the interface of the hot melt explosion welded W/CuCrZr composite plate was explored. The results show that the interface bonding of the hot melt explosion welded W/CuCrZr composite plate is good and there is a cross-melting zone with 3–8 μm in thickness, but cracks are developed on the W side. The numerical simulation reproduces the changes of pressure, stress, strain and internal energy at the bonding interface in the process of hot melt explosion welding. The location of the crack generated in the experiment coincides with the high stress position calculated by numerical simulation. The high pressure and high temperature near the hot melt explosion welding interface further promote the bonding of the interface.
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Liu Xianghong, Zhao Ning, Wang Tao, Kang Jiarui, Yang Jing, Li Shaoqiang, Du Yuxuan
2024,53(11):3101-3110 DOI: 10.12442/j.issn.1002-185X.20240027
Abstract:The sub-stable β-type TB18 titanium alloy exhibits a significant strengthening effect through solutionizing-ageing and possesses excellent potential for achieving a balanced combination of strength and toughness. As a result, it has emerged as a favoured material for manufacturing high-end aviation components. This work aimed to investigate the impact of solid solution treatment on the microstructure and mechanical properties of TB18 titanium alloy. Specifically, the effects of different solution temperatures, solution times, and slow cooling rates after solutionizing on the alloy"s microstructure and mechanical properties were illustrated. The goal is to understand the mechanism behind the interaction between solution treatment and the microstructure-mechanical properties of TB18 titanium alloy. The results indicated that following the solutionizing and aging treatment within the β single-phase region, lamellar and needle-like αs phases precipitated within the β matrix. The presence of lamellar αs phases contributed to the improvement of the toughness of the TB18 titanium alloy. Furthermore, it was observed that the fracture toughness of the TB18 titanium alloy improved with an increase in the thickness of the lamellar αsphases. Elevated solutionizing temperature or prolonged solid solution holding time can result in the coarsening of β grains in TB18 titanium alloy, leading to a decrease in material strength and plasticity. When increasing the cooling rate from 0.25 ℃/min to 1 ℃/min after solutionizing, the fine αs phases uniformly distributed within the TB18 titanium alloy after aging treatment, and the tensile strength increased to 1343 MPa while the elongation was 5 %. By subjecting the TB18 titanium alloy to a solutionizing regime at a temperature of 870 ℃ for 2 hours, followed by air cooling, it achieved a favorable combination of strength and toughness. Further aging at 530 ℃ for 4 hours, again with air cooling, results in a tensile strength of 1315 MPa, yield strength of 1225 MPa, elongation of 8.5%, impact toughness of 29.2 J/cm2, and fracture toughness value of 88.4 MPa . m1/2.
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Luo Rui, Sheng Donghua, Wang Zixing, Gao Pei, Chen Leli, Xu Haoxiang, Cao Fuyang
2024,53(11):3111-3120 DOI: 10.12442/j.issn.1002-185X.20230537
Abstract:The hot deformation behaviour and microstructural evolution of a kind of Ni-Mo alloy (Hastelloy B3) were investigated by Gleeble-3500 thermal simulation tester in the temperature range of 950°C~1250°C, and in the strain rate range of 0.01~5 s-1. Electron backscatter diffraction (EBSD) was used to analyze the microstructure evolution. Arrhenius constitutive model of this alloy was developed on the basis of peak stresses. The microstructural evolution of Hastelloy B3 alloy during deformation was observed via an optical microscope. The critical strain of dynamic recrystallization (DRX) of Hastelloy B3 is identified based on the work hardening rate versus flow stress curves. The DRX kinetics for Hastelloy B3 alloy can be represented in the form of Avrami equation. The results show that DRX behaviour tends to occur at high temperatures and low rates of deformation parameters. According to the EBSD analysis of the grain boundary angle and dislocation density of the deformed organisation of the alloy, dislocations tend to accumulate at the original grain boundaries to form low-angle grain boundaries and then evolve into High-angle grain boundaries. Thus, the main DRX mechanism for Hastelloy B3 alloy is identified as discontinuous dynamic recrystallisation (DDRX) dominated by continuous dynamic recrystallisation (CDRX).
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WANG Xiaoxi, ZHANG Xiang, ZHANG Fei, XIA Xiaolei
2024,53(11):3121-3128 DOI: 10.12442/j.issn.1002-185X.20240213
Abstract:A novel process named Expansion Equal Channel Angular Pressing (Exp-ECAP) which couples multiple forms of deformation such as upsetting, shearing, and extrusion into one was proposed. Ti/Al bimetallic composite rod was successfully fabricated by a single pass of Exp-ECAP process at 450 ℃ combined with post annealing heat treatment. The interface microstructure and bonding properties of Ti/Al bimetallic composite rod were investigated using SEM, EDS, XRD, EBSD and shear test. The results show that under the severe shear stress of Exp-ECAP process and the high-temperature annealing conditions, the Ti/Al bimetallic composite rod achieves good interfacial bonding quality, and a metallurgical bonding layer of approximately 1.27μm thickness is appeared through mutual diffusion of the titanium and aluminum matrix elements. New phases generated in the bonding interface layer are mainly intermetallic compound TiAl, and a small amount of inhomogeneous distributed Ti3Al (near the titanium side) and TiAl3 (near the aluminum side) are also contained. Moreover, a large number of equiaxed ultrafine grains are obtained in the Ti/Al interface bonding layer through phase transformation reactions and partial recrystallization, and the grains grow randomly without obvious preferred orientation. The shear strength of Ti/Al bimetallic composite rod is about 66.29 MPa, and shear failure mainly occurs in the TiAl phase layer, exhibiting brittle fracture characteristics.
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Nan Wang, Jide Liu, Congwei Zhu, Zhipeng Zhang, Wei Xu, Jinguo Li
2024,53(11):3129-3135 DOI: 10.12442/j.issn.1002-185X.20230532
Abstract:In this research, the effects of solution time and long-term aging on microstructure evolution and mechanical properties of a traditional nickel-based single crystal superalloy under different heat treatment conditions were studied. The obtained results demonstrate that the best heat treatment regime is “1310℃/4h (AC)+1130℃/4h (AC)+899℃/16h (AC)”. After the solution treatment, the participating of adverse phase of TCP has been avoided to obtain the preferable microstructure with small size and a high degree of cubic of strengtheningγ′phase. The difference in creep rupture life and percentage of elongation is slight under different heat treatment regimes. During the deformation, the brittle TCP phase was broken first, demonstrating that it is not the crack initiation. However, the weak carbide/matrix interface in inter-dendrites is the source of the crack.
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chen xiang, liu lei, fu fukang, lu sheng, zhao yang, kang xi
2024,53(11):3136-3148 DOI: 10.12442/j.issn.1002-185X.20230542
Abstract:The state of stress concentration in a concave-convex self-expanding bracket with a structure that has a negative Poisson ratio was studied using NiTi UMAT program. It has been found that the support performance of the concave and convex bracket changes completely with the variation in the number of units (Nc) and the angle (θ) between the inclined bar and the horizontal direction of the support ring. The change in the axial distance of the support is primarily influenced by the parameters h/l and θ, and it exhibits a negative correlation. The dilation rate of a concave-convex stent in a diseased femoral artery can reach 90.3%, which is generally higher than that of existing self-dilation medical stents. The concave-convex stent can achieve uniform expansion when working in the femoral artery, thereby avoiding the issue of a narrow middle and wide ends. The Goodman fatigue curve and fatigue factor were evaluated, meeting the national requirements for medical stents.
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Tu Wenbin, Zhong Guohao, Wang Shanlin, Ke Liming, Chen Yuhua, Xu Muzhong, Yu Peitong, Wei Mingwei
2024,53(11):3149-3157 DOI: 10.12442/j.issn.1002-185X.20230546
Abstract:12Cr12Mo stainless steel is an important material for static blade ring of steam turbine. The heterogeneous microstructure and properties of welded joints of thick 12Cr12Mo stainless steel are often occurred. In this paper, 12Cr12Mo butt joint of thick plate was prepared by electronic welding. The microstructure and mechanical properties of the joint were studied. The results show that the inhomogeneity of microstructure and mechanical properties along with thickness are found. The fusion zone is mainly quenched martensite, the heat affected zone is the mixed microstructure of martensite and tempered sortensite, and the microstructure of base material is tempered sortensite. The grain size of the fusion zone decreases with the increase of the penetration depth while the grain size of the fusion zone decreases with the increase of the penetration depth. The grain size of the heat affected zone at different thickness positions is the same. However, the grain sizes of the heat affected zone are smaller than that of the fusion zone and the base metal. The tensile strength and hardness increase gradually as the penetration depth increase while the elongation decreases continuously. The fracture location of the layered tensile specimens appears in the fusion zone, and the fracture dimple becomes smaller and shallower with the increase of penetration depth. The difference of microstructure evolution caused by heat input and cooling rate along with thickness of the weld is the main reason for the inhomogeneity of microstructure and mechanical properties.
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Study on the Fabrication and Microstructure and Properties of Cu2Se by Using Selective Laser Melting
Zhang Linjie, Cheng Peixin, Wang Xiang, Long Jian, Ning Jie
2024,53(11):3158-3168 DOI: 10.12442/j.issn.1002-185X.20230548
Abstract:The main problem of SLM additive preparation of thermoelectric material Cu2Se is that Se element is easy to burn under the action of high energy density heat source of laser. At present, there is no commercially available Cu2Se powder for 3d printing, and no scholars have used SLM to prepare medium temperature thermoelectric material Cu2Se. In this study, laser-induced high-temperature self-propagating reaction + ball milling method was used to prepare Cu2Se powder with good fluidity for SLM additive manufacturing for the first time. Under the optimized process parameters, Cu2Se thermoelectric material additive parts with smooth surface, good mechanical properties and excellent thermoelectric properties were obtained. The grain growth of Cu2Se bulks prepared by SLM has obvious anisotropy in the horizontal and vertical directions. The grains in the vertical section are mainly slender columnar crystals with a length of about hundreds of microns growing along the deposition direction, and the horizontal section is an equiaxed crystal with a size of about tens of microns. There are nano-scale micropore defects at the grain boundaries on the horizontal section. The ZT values measured in the vertical and horizontal directions at 673 K are 0.74 and 0.33, respectively. The maximum compressive strength along the vertical and horizontal directions is 125.08 MPa and 42.69 MPa, respectively. The average microhardness of the additive is 62.5 HV. The thermoelectric properties of Cu2Se prepared in this study are comparable to those of Cu2Se prepared by traditional methods in the vertical direction, and the mechanical properties are good, indicating that it is feasible to prepare Cu2Se thermoelectric materials by SLM. This study opens up a new way for the preparation of medium temperature thermoelectric materials.
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Shi Qianshuang, Bai Run, Hua Xingjiang, Li Shilei, Hu Boliang, Zhang Wen, Hu Ping
2024,53(11):3169-3174 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.
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zhangtianyou, yanlizhen, lixiwu, yanhongwei, lizhihui, gaoguanjun, zhangyongan, xiongbaiqing
2024,53(11):3185-3193 DOI: 10.12442/j.issn.1002-185X.20230563
Abstract:Al-Mg-Zn alloy has moderate strength, excellent corrosion resistance and an age-hardening response through precipitating T-Mg32(Al, Zn)49 phases and it is expected to be used as structural material in aerospace and various types of hulls. Sc is one of the most effective microalloying elements in aluminum alloys. The primary Al3Sc phase formed during solidification acts as a nucleating particle to effectively refine the as-cast microstructure of the alloy, and the secondary Al3Sc phase formed during homogenization significantly inhibits recrystallization. Al3Sc particles have excellent thermal stability and can effectively improve the weldability of alloys. Due to the high price of Sc, the method of Sc and Zr compound addition is widely used in industry. The Al3(Sc, Zr) phase formed by adding Sc and Zr at the same time has similar physical and chemical properties to Al3Sc and can greatly reduce the cost while retaining the strengthening effect. In this paper, four Al-Mg-Zn alloys with different Sc/Zr ratios were studied, and the influence of Sc/Zr ratio on the mechanical properties of Al-Mg-Zn alloys in aged state was studied. Transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the effect of Sc and Zr microalloying on the precipitation of T-Mg32(Al, Zn)49 phase, and the contribution of different strengthening mechanisms to yield strength was quantitatively calculated. The results showed that a large amount of T phase is dispersed in Al-Mg-Zn alloy with small size, and different Sc/Zr ratio has no significant effect on T phase. The main strengthening mechanism of Al-Mg-Zn alloy was the precipitation strengthening of T phase, which contributes 283~297MPa to the strength. The contribution of solid solution strengthening to the strength of the alloy was 33~40MPa. The mechanical properties of the alloy were improved by the addition of Sc and Zr, and the properties of the alloy were increased by about 30MPa through grain boundary strengthening. The tensile strength of 0.13Sc-0.14Zr alloys and 0.17Sc-0.1Zr alloys was 551~552MPa and the yield strength was 461~463MPa.
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zhaomeng, zhouhui, heyanchun, guibinhua, wangkeliang
2024,53(11):3205-3210 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.
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Ci Jiliang, Gao Wenbo, Liu Jian, Zhang Jian, Jing Liangxiao, Yu Zhigang
2024,53(11):3211-3216 DOI: 10.12442/j.issn.1002-185X.20230577
Abstract:The present article focuses on the change of mechanical properties of oxide fiber reinforced ceramic matrix composites with temperature from room temperature (RT) to 1400 ℃. Alumina fiber reinforced silica composite (Al2O3f /SiO2) and quartz fiber reinforced silica composite (SiO2f/SiO2) were prepared by sol-gel process with alumina fiber and quartz fiber as reinforcement respectively. The tensile strength and compressive strength of the composites at room temperature ~1400 ℃ were investigated, and the microstructure and crystal phase structure of the composites were characterized by electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the mechanical properties of alumina fiber reinforced SiO2 composites are much higher than those of quartz fiber reinforced SiO2 composites under RT~1000 ℃. However, while the temperature was raised to 1200℃, the mechanical properties decrease sharply, and strong bonding occurs between silica particles and fibers. As the temperature was further increased to 1300~1400 ℃, mullite and α-quartzite phases were formed. The mechanical properties of composites are sharply decreased due to brittle fracture under the action of stress. The brittle fracture caused by the disappearance of interfaces is the main mechanism of high temperature failure of composites.
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WANG Zhong-tang, LIU Quan, LIANG Hai-cheng, LI Yan-juan, LIU Yong-zhe
2024,53(11):3217-3223 DOI: 10.12442/j.issn.1002-185X.20230586
Abstract:Numerical simulation method was used to study material flow law of magnesium alloy variable curvature panel formed by progressive bending technology (PBT). The experimental is completed, and several types of magnesium alloy variable curvature panel are obtained. The curvature radius of panel range is from 205.7 mm to 72.56 mm. The suitable process parameters for progressive bending of magnesium alloy variable curvature panel are determined. The results show that curvature radius of panel is related to amount of press height. As press height increases, radius of curvature of panel decreases. With increase of press height, absolute deviation between simulation results and experimental results decreases, and relative error increases. With increase of curvature radius of panel, absolute error increases and relative error decreases. For internal grid panel of magnesium alloy, and maximum relative error is 5.22%. For outer grid panel of magnesium alloy, and maximum relative error is 5.51%. The generatrix straightness method was used to evaluate the degree of concave defects on surface of magnesium alloy panel. With the curvature radius of panel decreased, the generatrix straightness deviation increased, and the generatrix straightness coefficient increased. When curvature radius of panel is 72.56 mm, the maximum deviation of generatrix straightness is 0.083 mm, and the corresponding maximum value of generatrix straightness coefficient is 0.237%.
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Guo Yupeng, Li Xin, Pan Moru, Lu Xiaofeng, Wei Zhenguo, Zhu Xiaolei
2024,53(11):3233-3240 DOI: 10.12442/j.issn.1002-185X.20230622
Abstract:The TiO2 coatings were prepared by micro-arc oxidation coupled with a high and low-frequency pulse. The low-voltage and high-frequency pulse promoted the electrodeposition of nano-particles and effectively improved the anticorrosion performance of the coatings. The number of micropores on the surface of the coatings decreased, the porosity of the coatings decreased from 2.72% to 0.896%, the thickness increased to 23.76μm, and the Ti content increased from 30.02% to 42.48%. The high-frequency pulse was applied to the nanoparticle suspension, and the content of Nb increased to 10.62%. The coatings comprised anatase, rutile, Al2TiO5, Nb2O5, and Nb-Ti compounds. The Nb peak value increases significantly under the high-frequency pulse. The corrosion current density decreased from 7.995×10-7 A/cm2 to 3.249×10-7 A/cm2.The high-frequency pulse accelerated the deposition of nano-particles into the coatings, and the low-voltage and high-frequency electromagnetic field accelerated the deposition of particles into the positive electrode electrophoresis, thus enhancing the performance of the coatings.
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XU Xiaoyan, Hao Qingbin, Jiao Gaofeng, Yao Kai, Liu Guoqing
2024,53(11):3241-3245 DOI: 10.12442/j.issn.1002-185X.20230617
Abstract:The Bi2Sr2CaCu2Ox(Bi-2212) multifilament round wires were fabricated by the powder-in-tube technique. Open ends and closed ends wires were heat-treated in 1atm flowing O2. Several samples at various points of the partial-melt processing were prepared. The influences of the gas content inside wires on the diameters, microstructures and the phase compositions were systematically investigated. The results showed that large amount of bubbles were residual during the partial melting process of Bi-2212 filaments in pure O2 atmosphere. Porosity agglonerated large bubbles on melting of the Bi-2212 powders. These bubbles were partially retained inside the final wires. High internal gas pressure would cause the molten phase towards the Ag layer to fill the defects, resulting the filament-to-filament bonding and the worse texture.
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Zhao Chen, Mu Weiyi, Ji Shouchang, Li Huan, He Fei, Jing Lei, Xu Bowen, Liang Lisi
2024,53(11):3084-3100 DOI: 10.12442/j.issn.1002-185X.20240063
Abstract:Since the magnesium and magnesium alloys have good load transmission, exceptional biosafety, unique biodegradability, etc, they have significant application possibilities in the field of medical implantation. Furthermore, excellent corrosion resistance is one of the paramount prerequisites for magnesium and magnesium alloys as medical implants. However, magnesium alloys exhibit poor corrosion resistance, leading to rapid degradation in physiological environments due to high corrosion rates. This premature degradation, before completing their intended service life, compromises their structural integrity, severely limiting their clinical applications. Surface modification treatment of magnesium alloy to improve corrosion resistance has become a research hotspot of medical magnesium alloy. This study primarily focused on the research advancements in the corrosion resistance enhancement of medical magnesium alloys. The developmental trajectory and characteristics of medical magnesium alloys were outlined. Additionally, surface modification techniques such as micro-arc oxidation and ion implantation, as well as microstructure and properties of magnesium alloy surfaces after surface modification were reviewed. The formation mechanisms of various coatings were discussed, and their structures and properties were analyzed. The impact of coatings on the degradation rate of magnesium alloys was elucidated, aiming to identify key issues and potential solutions in the implementation and application of surface modification for medical magnesium alloys. Recommendations were also provided, presenting the research directions for surface modification of medical magnesium alloys.
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LU Guoxin, LUO Xuekun, WANG Qiang, LIU Jide, WANG Xin, ZHANG Yongkang, LI Jinguo, LU Feng
2024,53(11):3246-3258 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.
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Fang Yaohua, Zhang Zhi, Wang Yongxin, Peng Jie, Zhang Haijun, Liu Jianghao
2024,53(11):3259-3270 DOI: 10.12442/j.issn.1002-185X.20230606
Abstract:Owing to their multiple outstanding properties including low density, high thermal conductivity, good ablation and thermal-shock resistances, Cf/C composites have great potentials in various high-end structural application fields such as hypersonic aircraft, aircraft braking systems and rocket nozzles, etc. However, the high oxidation sensitivity of Cf/C composite generally causes some severe problems including serious chemical ablation and significant degradation of service performances. To address these problems, the preparation of ZrB2-SiC-based ultra-high temperature ceramics (UHTCs) coatings on the surface of Cf/C composites is the most effective solution so far. Consequently, this paper reviewed the recent progress in the topics of compositional/microstructural modifications of ZrB2-SiC-based coatings, their oxidation resistances and enhancement mechanisms. Moreover, the principles as well as advantages/disadvantages of popular preparation methods of ZrB2-SiC-based ceramic coatings were systematically summarized, respectively. Based on this, the prospects of the promising directions of research and the technique development of this field were forecasted.
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Wang Yao, Li Jinshan, Chen Bo, Chen Mingju, Chen Biao, Wang Yi, Gong Weijia
2024,53(11):3271-3280 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.
2024,Volume 53, Issue 11
>Amorphous And High Entropy Alloy
>Materials Science
>Reviews
- Published Issue
- Call for Papers
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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: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.
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Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240464
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.
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Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240470
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.
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Wang Xingxing, Chen benle, Jiang Yuanlong, Pan kunming, Ren Xuanru, Yuan Zhipeng, Zhang Yulei
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240477
Abstract:As service conditions become more challenging and fabrication complexity increases, there is an increasing demand for enhanced comprehensive performance of ceramic/metal heterostructures. At present, brazing technology has been widely utilized for ceramic-metal heterogeneous joints. However, the residual stress relief in these welding joints is complicated and necessary. Because metals and ceramics have different properties, especially in their coefficients of thermal expansion (CTE). Welding joints exhibit large residual stresses during the cooling process. The relatively high residual stresses may significantly degrade the joint properties. For this issue, this paper systematically reviews four alleviation routes: optimization of process parameter, setting an intermediate layer, surface structure modulation, and particle-reinforced composite solder. Eventually, upcoming prospects and challenges of residual stress research on ceramic/metal heterostructures are pointed out..
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mengshuaiju, songjinlong, chenkeyi, cuimin, wanglidong, biguangli, caochi, yangguirong
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240480
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.
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Xu Yaxin, Zou Han, Huang Chunjie, Li Wenya
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240483
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.
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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: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.
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Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240492
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.
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Li Qianru, Zhang Fan, Niu Shiyu, Wang ying, Yang Zhenwen
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240495
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.
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Nan Lingxin, Qi Yanfei, Xu Pengfei, Li Yungang, Pang Binghe
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240509
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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Tian Qinghua, Hu Zhixiang, He Zhiqiang, Guo Xueyi, Zhu Liu, Xu Zhipeng
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240439
Abstract:High-purity indium finds extensive application in the aerospace, electronics, medical, energy, and national defense sectors. Its purity and impurity content significantly influence these applications. In this study, ultrahigh-purity indium was prepared by combining zone refining with vacuum distillation. The average removal efficiency of impurity Sb can approach 95%, while the removal efficiency of impurities Sn and Bi could reach over 95% and the removal efficiency of Si, Fe, Ni, and Pb could reach over 85%. Ultimately, the amount of Sn and Sb impurities was reduced to 2.0 ppb and 4.1 ppb, respectively, and the majority of impurities, including Fe, Ni, Pb, and Bi, were reduced to levels below the instrumental detection limit. The overall impurity removal efficiency was 90.9%, and the indium purity was 7N9.
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Zhang Xiaoyuan, Li Fuguo, Du Yuxuan, Liu Xianghong, Wang Kaixuan, Li Jieyao, Song Minglong
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240444
Abstract:Comparative analysis of the differences in tensile strength and impact toughness between the TC25 alloy and TC25G alloy of Ti-Al-Zr-Sn-Mo-W-Si system titanium alloys was carried out, and the root causes of the differences in impact toughness between the two alloys and the alloy strengthening mechanism were elucidated through the observation of the SEM fracture morphology and the analysis of the TEM microscopic deformation mechanism. The results show that the precipitated phase in the impact fracture of TC25G alloy is ZrSi or TiZrSi compounds, which plays the role of second-phase reinforcement and is conducive to the enhancement of the alloy strength, and the precipitates are conducive to the extension of impact cracks, thus reducing the impact toughness of the alloy. TC25 alloy impact fracture microstructure cracks generally extend along the primary α phase phase boundary, while TC25G alloy impact fracture microstructure cracks through the primary α phase; so that the TC25 alloy crack extension path longer, and thus the alloy has a higher impact toughness. TEM observations show that the number of dislocation slip traces and dislocation plugging in TC25G alloy is significantly higher than that in TC25 alloy. The presence of a large number of plugged dislocations in the vicinity of the precipitates in TC25G alloy results in significant strengthening, leading to a higher strength of the alloy.
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Gao Yubi, Wang Wenjuan, Yang Hui, Wang Xingmao, Xu Jiayu, Zhen Bing, Ding Yutian
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240445
Abstract:In this paper, EBSD, SEM, TEM and quasi-static uniaxial tensile tests were used to study the effects of temperature and twin boundaries on the mechanical properties and Protevin-Le chatelier（PLC) effect of GH3625 alloy. The results show that with the increase of annealing temperature (1000 °C~1160 °C), the recrystallized grains of the annealed specimen grow, resulting in the annihilation of part of the annealed twin boundaries, which reduces the content and strength of the annealed twin boundaries of the alloy. And it is found that the lower the annealing temperature, the greater the critical strain value of the alloy with PLC. At the same time, the tensile deformation of the annealed specimen at 25 °C and 290 °C is mainly dominated by dislocation slip and deformation twin, while at 565 °C, the dislocation slip is mainly dominated by dislocation slip, and a large number of lamination faults are formed. With the increase of deformation temperature, dislocations tend to pass through grain boundaries and annealed twin boundaries, resulting in PLC, weakened grain boundary strengthening effect, and decreased alloy strength. In addition, the specimen with an annealing temperature of 1000 °C has an excellent combination of strength and plasticity in the temperature range of 25 °C~565 °C, which is mainly attributed to the interaction of pre-existing fine grains and a large number of annealed twin boundaries with dislocations, as well as the combined effect of deformed twins and lamination faults formed during tensile deformation. In addition, it is found that the twin content and deformation temperature have a significant effect on the rheological amplitude of the PLC.
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Ge Mao, Jiang Haitao, Zhang Yun
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240449
Abstract:This paper focuses on the AZ31 magnesium alloy, utilizing single-pass hot rolling to fabricate an alloy with the bimodal grain structure, and examines how this structure enhances the alloy’s strength and plasticity. The experimental results show that the formation of the bimodal grain structure is more pronounced at rolling temperatures ranging from 350 ℃ to 450 ℃, especially under conditions of large reduction (≥40%). The optimized proportion and distribution of the bimodal grain structure play a pivotal role in simultaneously enhancing the alloy’s strength and ductility, significantly impacting the mechanical properties. The rolled sheet with the bimodal grain structure achieved an ultimate tensile strength of 258.3MPa and an elongation of 17.1% under a rolling reduction of 40%, with a rolling rate of 75 m/min and a rolling temperature of 400 ℃. Adjusting rolling parameters, including temperature, reduction ratio, and rolling rate, is crucial for optimizing the bimodal grain structure, thereby achieving a balance between improved plasticity and maintained high strength.
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Li changmin, Luo hengjun, Zhao ning, Guo shiqi, Wei minggang, Xiang wei, Cui mingliang, Xie jing, Huang liang
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240451
Abstract:The hot deformation behavior of as-extruded Ti-6554 alloy was investigated through isothermal compression at 700-950 °C and 0.001-1 s-1. The temperature rise under different deformation conditions was calculated, and the curve was corrected. The strain compensation constitutive model of as-extruded Ti-6554 alloy based on temperature rise correction was established. The microstructure evolution under different conditions was analyzed, and the dynamic recrystallization (DRX) mechanism was revealed. The results show that the flow stress decreases with the increase of strain rate and the decrease of deformation temperature. The deformation temperature rise gradually increases with the increase of strain rate and the decrease of deformation temperature. At 700 °C/1 s-1, the temperature rise reaches 100 °C. The corrected curve value is higher than the measured value, and the strain compensation constitutive model has high prediction accuracy. The precipitation of the α phase occurs during deformation in the two-phase region, which promotes the DRX process of the β phase. At low strain rate, the volume fraction of dynamic recrystallization increases with the increase of deformation temperature. The DRX mechanism includes continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX).
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guozilong, lizhaoxi, guowei, liupengkun, lijinglong, xiongjiangtao
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240452
Abstract:This study focuses on the transient liquid phase (TLP) diffusion bonding of GH5188, utilizing a BNi-5 interlayer. Parameters were chosen and optimized for GH5188 alloy and the TLP joining mechanism.SThe microstructure evolution and mechanical properties of the joints were comprehensively examined.SThe relatively complete isothermal solidification zone (ISZ) ensured a reliable connection of the base metal (BM).SInS1110 °C to 1190 °C, higher bonding temperature widened the ISZ and enhanced joint composition homogenization, improving mechanical properties.SHowever, an increase in precipitatedSadversely affected the joint"s mechanical properties.SThe maximum shear strength, reaching 482 MPa, was achieved at 1130 °C, representing 84.6% of the BM strength.SWithin theSpressure range of 5 MPa to 15 MPa, both precipitation phases in the ASZ and voids generated by partial melting increased.SOn the contrary, their sizes decreased significantly with higher bonding pressure, resulting in an upward trend in alloy mechanical properties.SThe maximum shear strength of 490 MPa was attained at a bonding pressure of 15 MPa. The joint exhibited a typical mixed fracture pattern, with the small brittle M23C6 phase and voids significantly impacting mechanical properties.SNanoindentation tests indicated the ASZ as a potential source of cracks.
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Jiang shihui, Di Jinnan, Xu Zaidong, Sun Ssihua, Mao Pingli
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240453
Abstract:In this work, a near β-type Ti-5.5V-4Mo-2.2Cr-Fe-3.6Al alloy was designed based on the multi-alloying principle of critical molybdenum equivalent ([Mo]eq), combined with parameters such as electron concentration (VEC), Bo-Md that can influence the stability of β phase. The alloy was subjected to solid solution, intermediate annealing during the rolling process, and aging treatment. The microstructure and mechanical properties of the alloy were analyzed. The results showed that martensitic transformation occurs in the alloy during rolling. The grain size of the alloy after annealing during the rolling process is only 38 μm, due to the martensite has a hindrance to grain boundary migration. Then it has good strength-plasticity matching, the tensile yield strength reaches 1150 MPa and the elongation is more than 10%. A large number of α phases are precipitated in the microstructure of the rolled alloy after aging treatment, which further improves the properties of the alloy. The strength of the alloy exceeds 1500 MPa and the elongation is more than 5 %.
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Xing Quanyi, Zhou Ge, Zhang Haoyu, Che Xin, Wang Wen Jingzi, Chen Lijia
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240455
Abstract:In this paper, self-designed Al8Si0.4Mg0.4Fe aluminium alloy was modified with Sr, and a solid solution + aging treatment was applied to the alloy to regulate its microstructure and properties. The results show that: after the modification treatment, the room temperature tensile strength of the alloy did not change much, the elongation at break slightly improved (1.82%→3.34%), and the electrical conductivity significantly increased from 40.1%IACS before the modification treatment to 42.0%IACS. After the modification, the alloy underwent a solid solution treatment at 515°C for 8 hours and subsequently an aging treatment at temperatures 180℃, 200℃, 220℃ and 240℃ for a duration of 6 hours. With the increase of aging temperature, the electrical conductivity increased monotonously from 41.4% IACS to 45.5% IACS, but the room temperature tensile strength increased first and then decreased. At 200℃, the electrical conductivity and room temperature tensile strength of the alloy showed a good coordination, the electrical conductivity was 42.5%IACS, and the room temperature tensile strength was 282.9MPa. When the aging temperature continues to rise, the alloy is overaged. Although the conductivity is still rising, the tensile strength at room temperature decreases sharply, and it is only 177.1MPa at 240℃.
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Jianbo Guo, Zhengjun Liu, suyunhai
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240458
Abstract:The failure of mechanical parts is mainly caused by three types of reasons: wear, corrosion, and fatigue. Among these three failure modes, wear and tear of mechanical components notably increase energy consumption and lead to substantial economic losses. Preparation of Fe-Cr-C-B-Ti-Y wear resistant cladding metals by plasma cladding method. The wear performance of cladding metals was analyzed using the MLS-23 rubber wheel wet sand wear tester. XRD, SEM, EBSD, and TEM were employed to examine the phase composition and microstructure of the cladding metals, followed by a discussion on the cladding metals strengthening and wear mechanisms. The results indicate that the microstructure of Fe-Cr-C-B-Ti-Y cladding metals is composed of austenite γ-Fe+M23(C,B)6 eutectic carbide+TiC hard phase. As the amount of Y2O3 added increases, the hardness and wear of the deposited metal show a trend of first increasing and then decreasing. When the Y2O3 content is 0.4%, the precipitation of TiC hard phase and M23(C,B)6 type eutectic carbides reaches its maximum, and the grain size in the microstructure is the smallest. The forming performance of the cladding metal is the best, and the wetting angle is the smallest, only 52.2 °. At this point, the rockwell hardness value of the cladding metal is 89.7 HRC, and the wear weight loss is 0.27g. The wear mechanism of cladding metals is mainly abrasive wear, and the material removal process involves micro cutting and plowing.
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Yihang Yang, Fang Yang, Jixing Liu, Yixuan He, Shengnan Zhang, Guo Yan, Pingxiang Zhang
Available online:November 21, 2024 DOI: 10.12442/j.issn.1002-185X.20240226
Abstract:Because of the special dimension effect and interface effect, thin film materials have unique advantages compared with bulk materials. It has been found that single-layer FeSe superconducting films grown on SrTiO3 (STO) substrates significantly increase the superconducting transition temperature (Tc), which makes the study of FeSe superconducting films a new direction to understand the mechanism of unconventional superconductors. In this paper, the recent research achievements on the preparation of Fe(Se,Te) superconducting films and the enhancement of Tc by stress effect and interface effect are reviewed.
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