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Quick Search     Adv Search   2024 Vol. 34, No. 03 Published: 2024-06-10   1 Application of first principles calculation on superconducting materials Hot! WANG Qingxiang，LI Shaoqiang，LAI Yunjin，CHANG Tao，LI An DOI: 10.13228/j.boyuan.issn1006-6543.20240048 In this paper, the basic principle of first principles in material calculation is briefly introduced, and its progress in the research of superconducting materials, especially in the field of superconductivity, is summarized, which provides theoretical support for the further development of new superconducting materials and their practi‐ cal application; The shortcomings and suggestions of first principles calculation in the field of superconducting materials are put forward, and its research prospect in the mechanism of superconducting principles is prospected. 2024 Vol. 34 (03): 1-7 [Abstract] ( 22 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 8 Study on the chemical chain combustion reactivity of copper-iron composite oxygen carrier prepared by Bayan Obo iron ore concentrate and CuO Hot! HAN Aimin, SUI Zifeng, ZHANG Pengfei, WANG Qihao, Lü Qinggang, CHEN Weipeng DOI: 10.13228/j.boyuan.issn1006-6543.20230023 Bayan obo iron ore, coexisting with multiple valuable minerals such as iron and rare earth elements, ex‐ hibits high reactivity, abundant resources, and low cost. By employing the calcination synthesis method, a mixture of this ore with copper oxide is prepared into a spinel CuFe2O4 oxygen carrier, aiming to develop a performance-op‐ timized, cost-effective, and environmentally friendly oxygen carrier for chemical looping combustion. The reduc‐ ibility and cyclic stability of the oxygen carrier were investigated through thermogravimetric analysis and small fixed-bed experiments, complemented by XRD characterization for an in-depth analysis of reaction characteristics and mechanisms. The results demonstrate that the addition of copper significantly enhances the activity of the iron concentrate oxygen carrier, improves the high-temperature resistance and anti-sintering stability of the copper ox‐ ide oxygen carrier, and forms a more stable spinel structure of CuFe2O4, exhibiting excellent synergistic effects. The CO program warming test illustrated that the reduction reaction of the copper-iron composite oxygen carrier primarily involves CuFe2O4, proceeding in three stages: in the first stage, CuFe2O4 is reduced to Cu and Fe3O4 at low temperatures with the highest reactivity; the second and third stages involve the reduction of Fe3O4 to FeO and then FeO to Fe, respectively. During 26 reduction-oxidation cycles, the CuFe900 oxygen carrier displayed no sig‐ nificant sintering, maintaining good reactivity and cyclic stability. 2024 Vol. 34 (03): 8-14 [Abstract] ( 18 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 15 Study on direct reduction of iron ore powder at low temperature Hot! BAI Chenchen，YANG Guangqing，WU Longfei，MA Baoliang DOI: 10.13228/j.boyuan.issn1006-6543.20230051 The main ironmaking processes in China are blast furnace ironmaking and smelting reduction, both of which are high temperature metallurgical processes with high energy consumption, while the gas-based reduction method with low smelting temperature is difficult to develop due to the limitation of domestic natural gas resourc‐ es. The coal-based direct reduction method develops slowly due to high energy consumption and low productivity. In order to reduce its energy consumption and reduction cost, in this paper, the reduction mechanism between different iron ore powder and coal powder is studied by differential thermal analysis experiment. Through the dif‐ ferential thermal analysis of coal powder with different proportions of iron ore powder, the best method of direct reduction temperature of iron ore powder is expected to be found. The results show that PB powder ore relative to vanadium and titanium iron ore reduction process in the consumption of coal powder less coal ratio is lower, but the maximum heat absorption is slightly higher than the two vanadium and titanium iron ore powder. When PB powder and anthracite are selected, and the ratio of carbon to oxygen is 1.25, namely, the carbon content is 24.45% of the mass of iron ore powder, the reaction temperature of iron ore powder reduction is the lowest. At this time, the initial reaction temperature is 1 025 °C, and the violent reaction temperature is 1 210 °C. 2024 Vol. 34 (03): 15-20 [Abstract] ( 17 ) HTML (1 KB)  PDF  (0 KB)  ( 5 ) 21 Microstructure and properties of 90W-6Ni-4Mn alloy with low W-W contiguity by metal injection molding Hot! WU Wei，DENG Jikun，REN Boyong，LIU Junwu，ZHONG Honghai，JIANG Yang DOI: 10.13228/j.boyuan.issn1006-6543.20230036 As a new generation of kinetic energy armor-piercing projectile materials, the preparation of 90W-Ni- Mn alloy has the problems of high W-W contiguity, low sintering density and high processing cost. In order to solve these problems, the tungsten powder is treated with electroless nickel plating, and take shape using the feedstock by injection molding process, and then cooperate with the self-developed new argon-argon hydrogen twostep sintering process to prepare a 90W-6Ni-4Mn alloy with low W-W contiguity. Experiments show that 90W-6Ni- 4Mn alloy can be nearly net shaped, and the new sintering process can not only reduce W and Ni oxides content, but also avoid the generation of MnO. The relative density of the prepared sample reaches as high as 99.2%, the bonding phase distribution is uniform, and the W-W contiguity is low. Through microstructure and fracture morphology analysis, it is found that electroless nickel plating can promote the activation and sintering of tungsten skeleton, improving the density of alloy and promoting the uniform distribution of bonded phases. The 90W-6Ni-4Mn alloy as made with low W-W contiguity slows down the failure rate due to the reduction of the weak interface of WW, resulting in the compressive strength and tensile strength are as high as 1 583.4 MPa and 968 MPa, and the well plasticity and toughness of 21.5% and 5.3 J/cm2, respectively. 2024 Vol. 34 (03): 21-27 [Abstract] ( 15 ) HTML (1 KB)  PDF  (0 KB)  ( 5 ) 28 Study on the evolution of dislocation loops and radiation hardening effect in FeCrAl ODS steel Hot! LONG Dijun，XU Haibo，SUN Yongduo，Lü Junnan DOI: 10.13228/j.boyuan.issn1006-6543.20240015 In order to study the radiation resistance of FeCrAl ODS steel, the evolution of dislocation loops in Fe‐ CrAl ODS steel under irradiation was studied using in-situ ion irradiation method, and the irradiation hardening effect of FeCrAl ODS steel was characterized using nanohardness. The research results indicate that after ion irradiation, FeCrAl ODS steel produces<100>and 1/2<111>dislocation loops, and the average diameter and density of dislocation loops increase with the increase of irradiation damage dose. As the irradiation temperature increases, the growth rate of dislocation loops increases while the number density decreases. After 10 dpa ion irradiation, the irradiation hardening value of FeCrAl ODS steel is only 0.35 GPa, indicating good resistance to irradiation hardening. 2024 Vol. 34 (03): 28-33 [Abstract] ( 19 ) HTML (1 KB)  PDF  (0 KB)  ( 5 ) 34 Effect of pore forming agent content on porous nickel plate prepared by powder rolling Hot! YIN Quanzhong，LI Xiaoqiang，LIANG Yongren，LI Rong，REN Shangyuan，KANG Zhixin DOI: 10.13228/j.boyuan.issn1006-6543.20230034 Porous nickel plates with porosity of 22.2%-52.4% were prepared by powder rolling technology using ammonium bicarbonate（NH4HCO3）as pore-making agent. The effect of pore-forming agent content on microstructure and properties of porous nickel plate was studied. The results show that with the increase of pore-forming agent content, the porosity of porous nickel plate increases gradually, the relative permeability increases gradually, and the tensile strength decreases gradually. When the content of pore-forming agent is 20%, the porosity of porous nickel plate is 40.7%, the relative permeability coefficient is 10.79 m3/(h·kPa·m2), and the tensile strength is 135 MPa. When the content of pore-forming agent is 40%, the porosity of porous nickel plate is 52.4%, the relative permeability coefficient is 41.0 m3/(h·kPa·m2), and the tensile strength is reduced to 51 MPa. 2024 Vol. 34 (03): 34-39 [Abstract] ( 16 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 40 Effect of gradient structure of Al-Si-Cu-Ni alloy on bending properties Hot! SHI Zhichao，YAN Biao YAN Pengfei DOI: 10.13228/j.boyuan.issn1006-6543.20240062 Al-Si-Cu-Ni gradient-structured alloys were prepared under different process parameters by varying the laser power during selective laser melting and forming, and the bending properties were tested under positive and negative pressure conditions. After optimizing the process parameters, the comprehensive mechanical properties of the gradient-structured alloys were improved, the microstructures at different locations on the sides were observed, and the hardness distribution was tested. The results show that the bending properties under positive pressure conditions are better than those under counterpressure. With the increase of laser power, the microstructure is gradually coarsened, the precipitation amount of Cu-rich and Ni second phases increases, and the Vickers hardness and Brinell hardness linearly decrease, which makes the alloy samples produce a gradient structure. The bending strength and fracture displacement of the gradient-structured alloys prepared under the optimal process parameters under positive pressure can reach (838±22) MPa and (0.93±0.04) mm, which are significantly higher than those of the homogeneous structure alloys ((767±24) MPa, (0.85±0.03) mm), indicating that the gradient structure produces a toughening effect on the alloy materials, which is mainly attributed to the high strength of the fine-crystalline tissues, good plasticity of the coarse-crystalline tissues, and good plasticity of the coarse-crystalline tissues. The synergistic effect of the gradient structure on the alloys is mainly attributed to the high strength of the fine-crystalline tissue and the good plasticity of the coarse-crystalline tissue. 2024 Vol. 34 (03): 40-45 [Abstract] ( 15 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 46 Research on hot deformation behavior of a novel P/M superalloy based on Arrhenius and artificial neural network model Hot! WANG Minxi，LIU Jiantao，ZHANG Yiwen DOI: 10.13228/j.boyuan.issn1006-6543.20220221 Nickel-based superalloy strengthened by γ′ phase (L12 structure) has excellent high temperature strength, great plasticity and outstanding damage tolerance. These properties make it irreplaceable in many areas, such as aerospace industry and nuclear power industry. Meanwhile, a series of problems such as segregation, inhomogeneity and poor hot working performance coming from traditional casting/forging superalloy have been solved by powder metallurgy process. Nowadays, powder superalloy has become the first choice of key hot end components such as turbine disc of advanced aero-engine and powder superalloy has become an important symbol of engine advancement. To obtain desired mechanical properties, superalloy is usually fabricated by extrusion, hot forging and other processes. Therefore, it is of great importance to study the hot deformation behavior of superalloy. To study the hot deformation behavior of superalloy, constitutive model is applied to describe the relationship between flow stress and deformation parameters. Among many constitutive models, Arrhenius-type constitutive model is widely and commonly used in describing deformation behavior of nickel-based superalloy. Through the regression analysis, the relationship between flow stress and strain rate, deformation temperature is established and deformation parameters can be optimized to acquire superalloy with homogeneous microstructure and excellent mechanical properties. However, because of the complex none-linear characteristics of deformation parameters on flow stress, it is difficult to predict the flow behavior precisely. Thus, tools to describe this relationship more accurately are urgently needed. Deep learning tools, such as artificial neural network (ANN), is the promising way to solve this problem. ANN has the ability of self-learning, self-adaptation, strong nonlinear function approximation and fault tolerance. Meanwhile it does not rely on mathematical models and deformation mechanisms. Through the adjustment of the internal connections between a large number of nodes, ANN can achieve the purpose of information processing and predict more accurate than other constitutive models. The effect of deformation temperature and strain rate on hot deformation behavior of the PM superalloy was investigated. The change in flow stress during hot deformation actually is the competition between work hardening (dislocation accumulation, dislocation interaction, etc.) and softening mechanism (DRV, nucleation, grain growth, etc.). The AARE and R of typical Arrhenius-type model is as large as 23.36% and 0.965 8. After the modification in strain, the AARE and R drops to 9.92% and 0.988 7, respectively. While BP-ANN model is adopted, the value of AARE and R slumps to 1.75% and 0.999 5. BP-ANN performs better in dealing with the complex relationship between deformation parameter and flow stress. 2024 Vol. 34 (03): 46-53 [Abstract] ( 15 ) HTML (1 KB)  PDF  (0 KB)  ( 5 ) 54 The investigation of effects of surface grooves on friction disc on drag torque and heat dissipation in wet clutches Hot! XU Chengfa，ZHANG Kun，ZHANG Deng，ZHANG Guohong，WEI Bingzhen，HU Zheng DOI: 10.13228/j.boyuan.issn1006-6543.20220207 The friction pairs in wet clutches can cause drag torque and associated energy loss, when friction discs are not engaged, due to the viscous fluid nature of the lubricant subjected to relative motion between the friction pairs. This phenomenon is detrimental to the service life of wet clutches and causes concern of risk. In addressing this issue, based on the Navier-Stokes equation, a total of 12 groove designs with 24 configurations are designed and analyzed by means of finite element numerical simulation to explore the methods of reducing the drag torque and energy loss. The results show that the combination of spiral groove and radial non-slot design has good cooling effect and high dynamic friction coefficient. This paper provides an important reference for the design of friction pairs oil grooves, which is of great significance for guidance. 2024 Vol. 34 (03): 54-59 [Abstract] ( 13 ) HTML (1 KB)  PDF  (0 KB)  ( 5 ) 60 Optical in-situ observation and analysis of macro and micro characteristics of lubrication layers with different powder thickness Hot! KONG Junchao，WANG Gang，DONG Huifang，CHEN Yuxiang，NIU Tianliang，MENG Xiangcheng DOI: 10.13228/j.boyuan.issn1006-6543.20230052 Based on the linear reciprocating in-situ observation tester, the effects of powder layer thickness on interface wear condition, friction characteristics and real contact area ratio in 30 strokes were analyzed. The results show that thickness of powder layer is 1.5 μm, the powder layer is relatively thin on the surface of specimen. Asperities in some areas is initially exposed, and powder lubrication film is not formed. Main load is the contact load of asperities and serious wear marks appear. The initial real contact area ratio is 11.17% and finally decreases to 20.14%. The powder layer is 4.5 μm that the good lubrication film is formed in the area completely covered by the powder layer, and finally the lubrication film is completely peeling off and load is reduced. The powder layer is 6μm that powder layer completely covers the contact area and form complete lubrication film, load of powder layer is dominant and there is no scratch. Load first increases to 6 N and then decreases to 2 N, and asperities bearing capacity 2 N accounts for 33% of the total load. Friction ratio of powder layer is more than 73.3% and the real contact area ratio remains above 60%. The results shows that powder layer thickness is 6 μm that the powder has good flatness, high carbon content, full contact and good lubrication. 2024 Vol. 34 (03): 60-66 [Abstract] ( 13 ) HTML (1 KB)  PDF  (0 KB)  ( 5 ) 67 Synthesis and forming behavior of aluminum-based hybrid powder metallurgic composites Hot! ZHENG Xigui，Lü Ganglei，ZHU Yonggang DOI: 10.13228/j.boyuan.issn1006-6543.20230057 Aluminium-based metal matrix composites were synthesized from Al、TiO2 and Gr powder mixtures using the powder metallurgy technique and their forming characteristics were studied during cold upsetting. The powder preforms were pressed with a 40 kN hydraulic press with appropriate punches and dies, and then sintered in an electric furnace at 590 ℃ for 3 h in an air atmosphere. The sintered preforms were subjected to incremental compressive loads of 10 kN until cracks were found on the free surface. Axial stress (σz), hoop stress (σθ), mean stress (σm) and effective stress (σeff) were calculated for all pre‐ forms, which are related to the axial strain (εz).The densification behavior of the composites under axial strain (εz)and transverse strain was investigated.It is observed that the addition of 5% TiO2 into the Al matrix increases σz, σθ, and σm. The addition of both TiO2 and Gr reinforcements reduces the densification and deformation characteristics of the sintered preforms during cold upsetting. 2024 Vol. 34 (03): 67-74 [Abstract] ( 14 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 75 Study on reaction feeding mode of Ni0.55Co0.5Mn0.40(OH)2 with small particle size Hot! LIU Jiying，LI Zhilin，LIU Fei，LI Peng，YANG Yongsheng DOI: 10.13228/j.boyuan.issn1006-6543.20230056 Based on coprecipitation, in this paper, the effects of feeding sequence, feeding position, feeding tube number and feeding temperature of nickel-cobalt-manganese sulfate solution, alkali solution and ammonia solution on Ni0.55Co0.5Mn0.40(OH)2 were studied. The results show that Ni0.55Co0.5Mn0.40(OH)2 with high performance can be synthesized through method that Ni-Co-Mn liquid, ammonia liquid and alkali liquid as feeding sequence, Ni-Co- Mn liquid is fed up, alkali-ammonia liquid is fed down, Ni-Co-Mn liquid and alkali liquid are fed two points and 40-45 ℃ feeding temperature of Ni-Co-Mn solution. 2024 Vol. 34 (03): 75-78 [Abstract] ( 15 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 79 Effects of laser power and exposure time on microstructure and mechanical properties of selective laser melting of TC11 titanium alloy Hot! CHENG Zonghui，BAI Bing，CAI Xiaoye，HU Jiaqi，DONG Dingping DOI: 10.13228/j.boyuan.issn1006-6543.20220174 TC11 titanium alloy samples were formed by selective laser melting technology, the effects of laser power (220-260 W) and exposure time (45-55 μs) on the microstructure and mechanical properties of the samples were studied. The results show that the laser power and exposure time mainly affect the laser power density during the forming process, resulting in differences in microstructure and mechanical properties：when the laser power density increases, the liquid retention time is relatively long, the cooling rate is relatively low, the columnar crystal size is relatively large, and the martensite lath size increases; When the exposure time is 50 μs and the laser power is increased to 260 W, the microhardness of SLM forming specimen increases to 437 HV0.3, the tensile strength increases to 1 463 MPa, and the elongation after fracture decreases to 6.0%; When the laser power is 200W and the exposure time is increased to 55 μs, the microhardness of SLM formed specimen increases to 404.2 HV0.3, the tensile strength increases to 1 446 MPa, and the elongation after fracture decreases to 4.8%. When the laser power is 220 W and the exposure time is 50 μs, TC11 titanium alloy with better matching strength and plasticity can be obtained, and its tensile strength and elongation after fracture are 1 345 MPa and 10.6% respectively. 2024 Vol. 34 (03): 79-84 [Abstract] ( 12 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 85 Effect of ambient temperature on microstructure and properties of Fe3Al intermetallic compound porous materials Hot! YANG Junjun，ZHANG Yu，LIU Guanying，GUO Huijin，PING Shaobo，JI Liqiang DOI: 10.13228/j.boyuan.issn1006-6543.20240024 Fe3Al porous metal filter element is especially suitable for precision filtration and gas-solid separation under high-temperature high-pressure and corrosive environment. In order to meet the usage requirements of the filter element, in addition to considering its pore characteristics, its mechanical properties are also crucial. Fe3Al intermetallic compounds porous materials were prepared by powder metallurgy technology in this paper. The effects of ambient temperature on the pore characteristics, , mechanical properties and microstructure of the porous materials were studied by XRD, SEM, pore structure and mechanical properties. It shall provide a reliable basis for the use of Fe3Al porous materials at high temperature. The experimental results show that Fe3Al porous materials have good tensile strength and permeability properties at medium and high temperature. The tensile strength reaches the maximum at 300 ℃ and then decreases with the increase of temperature, and decreases obviously when the temperature is higher than 700 ℃. The fracture belongs to brittle fracture. The order degree of the Fe3Al intermetallic compounds porous materials changes with the increase of temperature. 2024 Vol. 34 (03): 85-90 [Abstract] ( 13 ) HTML (1 KB)  PDF  (0 KB)  ( 5 ) 91 Microstructure and wear resistance of CoFeNiCrNb 0.5 high entropy alloy cladding layer Hot! LING Zongyou DOI: 10.13228/j.boyuan.issn1006-6543.20240046 In this study, the CoFeNiCrNb0.5 high entropy alloy cladding layer was fabricated on the surface of 316L stainless steel by plasma cladding technology. The microstructure, phase composition, element distribution and wear resistance of the cladding layer of CoFeNiCrNb0.5 high entropy alloy were studied. The results show that the phase composition of the cladding layer of CoFeNiCrNb0.5 high entropy alloy is composed of FCC phase and Laves phase with face-centered cubic structure. Among them, the FCC phase is the matrix phase, and the Laves phase is formed at the interdendrite. The microhardness of the cladding layer of the CoFeNiCrNb0.5 high entropy alloy is about（510.5±14.2）HV, which is about 2.1 times that of the 316L matrix. The higher hardness of the cladding layer is mainly caused by the solid solution strengthening of Nb element and the diffusion strengthening of Laves phase. In addition, the CoFeNiCrNb0.5 high entropy alloy cladding layer has excellent wear resistance, and the specific wear rate is about 5.9×10-6 mm3/N·m, which is significantly better than the stainless steel substrate. Abrasive wear is the main wear mechanism of CoFeNiCrNb0.5 high entropy alloy cladding layer. 2024 Vol. 34 (03): 91-96 [Abstract] ( 13 ) HTML (1 KB)  PDF  (0 KB)  ( 5 ) 97 Development and preparation of ultrafine iron powder Hot! ZHANG Lijun，LI Yanchun，GUO Yufeng，LIU hui DOI: 10.13228/j.boyuan.issn1006-6543.20220218 The technology of producing ultra-fine iron powder by hydrogen reduction is studied, using iron oxide red of pickling waste in steel works as raw material, the cost is less than one third of the cost of producing ultrafine iron powder by carbonyl method. The properties of the products are TFe≥98.5% , loose density is 0.80~1.20 g/cm3, free grain size D50≤16.5 μm, specific surface area is more than 2.10 m2/g. It is widely used in ultra-hard diamond tools, powder metallurgy injection molding materials, high-specification soft magnetic materials, adsorption materials, aerospace materials, food and other fields. 2024 Vol. 34 (03): 97-100 [Abstract] ( 12 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 101 Characterization of H13 alloy special powders prepared by plasma rotating electrode atomization Hot! QIAO Zhenxing，LIU Zenglin，ZHANG Dejin，SUN Jing，CHEN Linlin，KAN Hongcheng DOI: 10.13228/j.boyuan.issn1006-6543.20230141 This paper describes a production process for the preparation of H13 alloy special powders by plasma rotating electrode atomization (PREP), including raw material preparation, atomization, and powder grading. The morphology, particle size, composition, fluidity and bulk density of the powder were tested by using scanning electron microscope, particle size analyzer, nitrogen-sulfur meter, ICP, Hall flow meter and bulk density meter. And a comparison was made with the powder produced by a domestic company using aerosolization (AA). The result shows that the surface quality of H13 alloy powder produced by PREP is excellent, with high powder sphericity, clean surface and almost no satellite powder, adhesive powder and hollow powder. The surface morphology is mainly fine dendritic organization with uniform organization. The physical properties of the powder are excellent, with high bulk density (4.6 g/cm3) and good flowability (12.8 s/50g). The particle size of the powder is centrally distributed, and the yield of the powder of specific size is high. However, the yield of fine powder is not high, and further optimization of the process is needed. The surface quality of H13 alloy powder prepared by AA is poor, with more satellite powder, shaped powder and adherent powder, and more surface defects. In addition, the physical properties are poor, and the fluidity and bulk density are not as good as the requirements of powder products. 2024 Vol. 34 (03): 101-105 [Abstract] ( 14 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 106 Study on selective laser melting of Al-Mg-Mn alloy under PLC control and its microstructure and properties Hot! SONG Liming，ZHANG Dajun，XU Buxin，LUO Zhixiang DOI: 10.13228/j.boyuan.issn1006-6543.20220231 The selective laser melting forming system based on PLC control was used for rapid forming of Al-Mg- Mn alloy. The effects of laser scanning speed on the density, microstructure, phase and hardness of the formed parts were studied, and the effects of aging temperature and time on the compression properties of the formed parts were investigated. The results show that with the laser scanning speed increasing from 700 mm/s to 1 300 mm/s, the porosity of the formed sample increases and the relative density decreases gradually under the condition of other process parameters unchanged. With the increase of laser scanning speed, the weld pool parallel to the deposition direction gradually increases, and the fusion line becomes thinner. Multilayer deposition channels with cross distribution can be seen perpendicular to the deposition direction, but when the laser scanning speed is 1300mm/s, the weld channel contour is relatively vague; At the same laser scanning speed, the hardness of the plane parallel to the deposition direction is higher than that of the plane perpendicular to the deposition direction. With the increase of laser scanning speed, the microhardness of XZ plane and XY plane first increases and then decreases, and the maximum hardness is obtained when the laser scanning speed is 900mm/s; With the increase of aging temperature or the extension of aging time, the microhardness, yield strength and compressive strength of the selective laser melting forming sample first increase and then decrease, and the maximum value is obtained when the aging temperature is 300 ℃ and the aging time is 6 h, which is mainly related to the precipitation strengthening effect of Al3(Sc,Zr) phase in the alloy at this time. 2024 Vol. 34 (03): 106-113 [Abstract] ( 11 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 114 Research progress in mechanical properties of refractory high entropy alloys Hot! CAO Zhenghang，WANG Wei，SUN Zhenzhong，HAI Yang DOI: 10.13228/j.boyuan.issn1006-6543.20230061 Compared with traditional alloys, high entropy alloys possess excellent mechanical properties, which have become a hot spot in recent years. Refractory high entropy alloy is mainly composed of refractory metal elements, which has high strength and high temperature resistance, so it has great potential for application in extreme environment. However, there are still some problems such as strength-plastic mismatch and poor processability in refractory high entropy alloys. It is the focus of research to regulate the microstructure of refractory high entropy alloys then improve strength and plasticity. In this paper, the preparation methods of refractory high entropy alloys were compared, the effects of regulating metal and nonmetal elements on microstructure and mechanical properties of refractory high entropy alloys were discussed. At the same time, the functions of thermal machining on mechanical properties of refractory high entropy alloys were investigated. 2024 Vol. 34 (03): 114-121 [Abstract] ( 7 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 122 Research progress of titanium hydroxyapatite biocomposites by powder metallurgy Hot! JIA Qinggong，WU Jiebei，ZHANG Jia，WANG Qingxiang，LIANG Shuhua DOI: 10.13228/j.boyuan.issn1006-6543.20220235 Titanium and titanium alloys have been widely studied and applied as biomedical metal materials. In order to better satisfy the requirements of low elastic modulus, biological activity after implantation in human body, the preparation of titanium based hydroxyapatite (HA) biological composites by adding hydroxyapatite with powder metallurgy has become a research hotspot. Based on the basic properties and existing problems of titanium and titanium alloys, this paper summarizes the research progress of titanium based HA biological composites by powder metallurgy such as hot pressing, powder injection molding, spark plasma sintering from the aspects of preparing biological composites to reduce elastic modulus, improve biological activity and corrosion resistance. The representative cases were listed separately which were preparation for titanium hydroxyapatite biocomposites by synthesis of α type, α+β type and β type titanium alloy with HA. Moreover, the challenges faced and suggestions for the development direction are also proposed. 2024 Vol. 34 (03): 122-129 [Abstract] ( 15 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 130 Anomalous surface analysis of tungsten infiltrated copper ablation Hot! DU Fangxin，ZHAO Fengxian，SUN Xiaoxia，GUO Yingli，TANG Liangliang，ZHANG Baohong DOI: 10.13228/j.boyuan.issn1006-6543.20230062 Aiming at the phenomenon of abnormal ablation on the surface of W-7Cu infiltrated with tungsten and copper, samples were taken from the rudder surface and guard plate of returned part, and the ablative characteristics, microstructure, surface debris, fracture morphology and metallographic structure of samples were compared and analyzed. The results showed that rudder surface’s ablation was more sever, both propellant residue on the surfaces were distributed, the fracture apperance was dominated by transgranular and intergranular fracture, no abnormal tissue was found; According to the results of metallographic and transmission electron microscope, the cavity of rudder surface is more than that of the guard plate, and copper leaks exist in both areas, energy spectrum analysis showed that the copper content has different gradients, the copper precipitation at rudder surface was significant that affected by three kinds of working conditions including temperature, time and scour speed. The study conclusions can provide a basis for subsequent failure analysis and quality control of tungsten-impregnated copper gas rudder products. 2024 Vol. 34 (03): 130-136 [Abstract] ( 12 ) HTML (1 KB)  PDF  (0 KB)  ( 5 )

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