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Chao Shuang, Cao Jingjing, Li Hezong, Fan Lei, Yang Junheng, Martin Harvey Christopher
2024,53(10):2723-2734 DOI: 10.12442/j.issn.1002-185X.20240245
Abstract:Ni-P-SiCP coatings were deposited on 42CrMo steel by electroless plating. The surface morphologies and phase structures of the Ni-P-SiCP coatings processed under different SiCP concentrations at different heat treatment temperatures were analyzed. The microhardness, corrosion resistance, and wear resistance of the Ni-P-SiCP coatings were studied. Results show that Ni-P-SiCP coatings exhibit cauliflower-like morphology. Increasing the SiCP concentration can reduce the size of cellular structure. The microhardness and corrosion resistance are initially increased and then decreased with the increase in SiCP concentration. The maximum microhardness and corrosion potential are 7379 MPa and -0.363 V, respectively, when the SiCP concentration is 5 g/L. The Ni-P-SiCP coatings exhibit an amorphous structure, and the width of the diffuse diffraction peak becomes narrower with the increase in SiCP concentration. It is suggested that SiCP inhibits the deposition of P and promotes the microcrystalline transformation. After heat treatment at 350 °C, the Ni-P-SiCP coatings are crystallized, resulting in the precipitation of Ni3P phase. Heat treatment at 400 °C for 1 h maximizes the structure. The synergistic effect of the Ni3P precipitate phase and SiCP dispersion phase promotes the densification of the cellular structure, leading to the optimal microhardness (13 828 MPa), optimal corrosion resistance (-0.277 V), and excellent wear resistance. The wear mechanism is dominated by micro-cutting abrasive wear with slight adhesive and oxidative wear.
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Li Hui, Chen Geng, Zhang Sheng, Liang Jinglong, Huo Dongxing, Yang Yu
2024,53(10):2735-2746 DOI: 10.12442/j.issn.1002-185X.E20240311
Abstract:A combined process of molten salt electro-deoxidation and vacuum hot-pressing sintering was proposed to prepare AlCrFeNiTix high-entropy alloy (HEA)-TiN ceramic coating composites on low-carbon steel surfaces, where nitrides were introduced from BN isolater between graphite mold and HEA powders. The effect of Ti content on the microstructure, ultimate tensile strength, hardness, and wear resistance of the composites was investigated, and the bonding mechanism was elucidated. Results demonstrate that the composites have excellent hardness and wear resistance. The hardness of composites is significantly increased with the increase in Ti content. The extremely high wear resistance is attributed to the extremely high melting point and high thermal hardness of TiN, which can effectively prevent oxidation deformation of the worn surface.
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Ma Kai, Feng Li, Zhao Yanchun, Liu Jianjun
2024,53(10):2747-2754 DOI: 10.12442/j.issn.1002-185X.20240095
Abstract:FeCrAlCu, FeCrAlCuNi, FeCrAlCuCo, and FeCrAlCuNiCo high-entropy alloy (HEA) coatings were synthesized on the surface of 45# steel through cold spraying-assisted laser remelting. Results reveal that all four HEA coatings are composed of face-centered cubic+body-centered cubic phases. Additionally, the microstructure of the coatings consists of columnar dendrites. With the simultaneous addition of both Ni and Co elements, the columnar dendritic grains are gradually refined in the coating. Moreover, the FeCrAlCuNiCo HEA coating exhibits excellent friction performance with the coating hardness of 5847.7 MPa, friction factor of 0.45, and wear rate of 3.72×10-5 mm3·N-1·m-1. The predominant wear mechanism is the adhesive wear and abrasive wear.
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Deng Zhenzhen, Dai Zhengfei, Wu Weibo, Lai Ruisi, Feng Qing, Jia Bo, Wang Chen, Lv Yuanjiang, Ma Fei
2024,53(10):2755-2765 DOI: 10.12442/j.issn.1002-185X.20240194
Abstract:To improve the corrosion resistance of titanium (Ti) bipolar plate, titanium nitride (TiN) film was prepared on the surface of commercial TA1 pure titanium by magnetron reactive sputtering and pulse laser deposition (PLD) techniques, and the film prepared under different process parameters were evaluated. Results show that dense and complete TiN film can be obtained on TA1 surface under different preparation processes, and the corrosion current density of Ti substrate significantly increases. However, the composition of the film prepared by magnetron reactive sputtering is affected by the oxygen competition reaction, and its homogeneity is inferior to that of the film prepared by PLD. The comprehensive performance of the PLD-prepared film shows excellent characteristics in the terms of low corrosion current density (0.025 μA·cm-2), moderate corrosion overpotential (-0.106 V), and good hydrophobicity.
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Zhang Ge, Tao Xipeng, Jafri Syed Muhammad Abbas, Wang Xinguang, Zhang Song, Zhang Chunhua, Liang Jingjing, Li Jinguo, Sun Xiaofeng, Zhou Yizhou
2024,53(10):2766-2776 DOI: 10.12442/j.issn.1002-185X.20240015
Abstract:The influence of applied temperatures on the creep rupture life of the third-generation low-cost single crystal (SX) superalloy with Pt-Al coating was evaluated. The creep damage was observed under the conditions of 1100 °C/137 MPa, 1120 °C/137 MPa, and 1140 °C/137 MPa. Results show that the properties of bare superalloy outperform those of coated superalloy under all test conditions. The most significant reduction in creep life reaches 50% when the test condition is 1100 °C/137 MPa. At higher temperatures (1120 and 1140 °C), the crack propagation rate in Pt-Al coatings to SX superalloy substrate decreases, thereby reducing the degradation degree of mechanical properties. Instead of the penetration into SX substrate, tip oxidation and Al diffusion of the coating cracks cause the formation of oxides, therefore leading to the slow degradation in microstructures of the substrate beneath the coating. At 1100 °C, however, the microstructure of coating/SX superalloy substrate degrades due to the Al internal diffusion. This diffusion mechanism promotes the formation of harmful topologically close packed phases around 1100 °C. At 1120 and 1140 °C, the dislocation of SX superalloy substrate beneath the coating is relatively unchanged, compared to that in the inner superalloy. In contrast, the dislocation network of the substrate beneath the coating becomes sparse, and the number of superdislocations cutting into γ′ phases increases at 1100 °C.
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Li Xuewu, Zhang Jiahao, Feng Yuxi, Liu Ming, Shi Tian, Wang Haidou, Bai Yu, Wang Yu
2024,53(10):2777-2785 DOI: 10.12442/j.issn.1002-185X.20240014
Abstract:High-performance yttrium oxide-phenolic resin (Y2O3-PF) alternating coating was prepared on epoxy resin-based composite material using supersonic plasma spraying and dual-channel powder feeding technique. Y2O3-coated PF (Y2O3/PF) powder was firstly sprayed onto the substrate, forming a transition layer, and then the spherical Y2O3 powder and Y2O3/PF powder were alternately deposited to form the composite alternating coating. Results show that the alternating coating is mainly composed of deposited Y2O3/PF powder. The bonding strength between coating and substrate is as high as 26.48 MPa with the single-test maximum bonding strength of 28.10 MPa, and shear strength reaches 24.30 MPa. Additionally, the heat transfer effect caused by external Y2O3 particles gradually softens and even melts PF, thus effectively avoiding the damage of high temperature to molecular structure and thereby promoting the crosslinking and curing effects of resin during the deposition process. In the meantime, the unmelted Y2O3 powder results in the shot peening effect, which washes out and eliminates the powder particles with inferior deposition effect, ultimately improving the physical and chemical properties of the alternating coating.
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Study of high-temperature oxidation behavior of electrodeposited Ni/Cr coatings on Zr alloy surfaces
Zhu Li''an, Yuan Weichao, Wang Shuxiang, Wang Zhen, Ye Yicong, Bai Shuxin
2024,53(10):2805-2800 DOI: 10.12442/j.issn.1002-185X.20240037
Abstract:After the Fukushima nuclear accident in Japan, accident tolerant fuel (ATF) cladding technology has attracted widespread attention in the industry. The cladding of Cr coatings on zirconium (Zr) alloys for nuclear fuel cladding in nuclear reactor cores is considered to be the most likely technology to be commercially available in the near future. At present, most of the preparation methods for Cr coatings have the disadvantages of expensive equipment, low deposition rate and weak shape adaptability. And the molten salt electrodeposition technology has the advantages of high cathodic current efficiency, fast electrodeposition speed, and strong adaptability of substrate shape, which is expected to solve the problem of efficient and low-cost preparation of high-quality Cr coatings on the surface of cladding Zr alloys. In order to realize the preparation of Cr coating on the surface of Zr alloy by molten salt electrodeposition, this paper adopted aqueous solution electrodeposition and molten salt electrodeposition methods to prepare Ni transition layer and Cr coating on the surface of Zr alloy substrate sequentially, and carried out the characterization of the organization structure, the bonding force and nano-hardness test as well as the study of the high-temperature oxidation behavior of the Zr/Ni/Cr specimens obtained from the preparation. The results showed that the Ni/Cr coating on the surface of Zr alloy was uniform and dense, and the bonding force between the coating and the substrate was about 151N. The hardness and modulus of elasticity of Zr/Ni/Cr increased gradually from inner to outer layers with a quasi-gradient transition. The surface roughness of the Cr coating was about 2 μm, and the hardness and modulus of elasticity were 2.86 GPa and 172.86 GPa, respectively. The Zr/Ni/Cr specimens showed nearly parabolic and nearly linear patterns during steam oxidation at high temperatures of 1000°C and 1200°C, respectively, indicating that the Ni/Cr coatings were able to provide good protection to the Zr alloy matrix at 1000℃. The high-temperature oxidation failure mechanism of Ni/Cr coatings on Zr alloy surfaces was closely related to the rapid diffusion of the Ni transition layer, the oxidation and diffusion depletion of the Cr layer, and the weakening of the Cr layer due to the rapid diffusion of Zr along the Cr grain boundaries.
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Shi Puying, Chen Lin, Pang Zhicong, Li Qinqin, He Weifeng, Liu Xianghong
2024,53(10):2823-2830 DOI: 10.12442/j.issn.1002-185X.20240390
Abstract:The fatigue crack propagation rate (da/dN) of bimodal structure Ti55531 titanium alloy before and after laser shock peening(LSP)was investigated. The fracture, microstructure and residual stress of fatigue crack propagation samples were analyzed. The results show that after laser shock, the fatigue crack growth rate da/dN decreased. When △K < 22.84MPa?√m, the sample BM-LSP has a lower fatigue crack growth rate than the sample without laser shock BM. When △K=22.84 the crack growth rates of the two samples were similar that is 3.92×10-4mm/cycle. After LSP, the length dispersion and thickness dispersion of the secondary α layer decreased by 22.9%, 38.9%, and the polar density of α and β phases decreased by 37% and 16%, respectively. The passivity of the lamer α tip and microstructure homogenization alleviated the stress concentration, resulting in a decrease in da/dN. In addition, the laser shock process introduces a residual compressive stress layer to a depth of about 900μm on the surface of the material. Residual compressive stress is also an important factor to offset tensile stress at crack tip, enhance crack closure and slow down crack propagation.
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MA Chi, ZHANG Conghui, ZHU Wenguang, ZENG Xiangkang, XIE Zhuohang, WANG Xiyu
2024,53(10):2831-2842 DOI: 10.12442/j.issn.1002-185X.20230506
Abstract:In this paper, the fatigue properties of Zr705 alloy in original state and ultrasonic rolling state after pre-corrosion in 1mol/L LiOH solution, 3.5% NaCl solution and 5% HCl solution for 30 days were studied. The results show that the corrosion degree of the original Zr705 alloy is the most serious in 3.5% NaCl solution, followed by 5% HCl solution and the least in 1mol/L LiOH solution. This is related to the different corrosion mechanism of Zr705 alloy in different media: when Zr705 alloy is in LiOH solution, mainly O2- and OH- participate in the corrosion reaction, while Li+ does not participate in the corrosion reaction, but is adsorbed on the pore wall of oxide film and the grain boundary of ZrO2 to accelerate the corrosion; When Zr705 alloy is in NaCl solution, a large amount of Cl- plays a leading role in the corrosion reaction. When Zr705 alloy is in HCl solution, both H+ and Cl- participate in the corrosion process of Zr705 alloy in HCl solution. USRP-Zr705 alloy is more easily corroded than the original Zr705 alloy because of the high density dislocation defects in the surface gradient structure. After immersion corrosion treatment, the fatigue life of the original Zr705 alloy decreased obviously, which was mainly caused by corrosion damage on the surface of the sample during immersion corrosion. After immersion corrosion treatment, the fatigue life of USRP-Zr705 sample in 1mol/L LiOH solution is higher than that of the original Zr705 alloy, but it is lower in 3.5% NaCl solution and 5% HCl solution. There is a competitive relationship between the corrosion environment and the surface gradient structure on the fatigue properties of zirconium alloys: when the corrosion medium is weak, the surface gradient structure is the main factor affecting the fatigue properties of zirconium alloys. When the corrosive medium is strong, the surface gradient structure is still the main factor affecting the fatigue properties of the alloy under high stress cyclic loading. Under low stress cyclic loading, corrosion environment is the main factor affecting the fatigue properties of the alloy.
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Liao Yehong, Dai Gongying, Yan Jun, Lin Xiaodong, Peng Zhenxun, Liang Xue, Li Yifeng, Xue Jiaxiang, Li Qiang
2024,53(10):2843-2851 DOI: 10.12442/j.issn.1002-185X.20230530
Abstract:The fretting wear behaviors of Cr-coated Zr-1Nb cladding tube with different griding pairs in simulated PWR primary water environment at 290 °C and 310 °C were studied by using three-dimensional optical surface profilometer, scanning electron microscope, electron back scattered diffraction and energy dispersive X-ray spectrometer. The results showed that the fretting wear behaviors between the Cr-coated Zr-1Nb cladding and griding pairs (i.e., Zr-4 dimple or Inconel 718 spring) were both dominated by the adhesive wear mechanism, accompanied by material transfer from the grinding pair to the Cr-coated cladding. With the increase of temperature, the fretting wear resistance of the Cr-coated cladding was decreased, as manifested by increased surface wear depth and volume. However, the fretting wear mechanism still remained unchanged within the temperature range tested in this work. In addition, the wear degree of the Cr-coated cladding with Zr-4 dimple was greater than that with Inconel 718 spring, which was thoughted to be related to the hardness and contact mode of the grinding pair.
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Chengling Kan, Yun Peng, Karin Gong, Changhai Li, Lin Zhao, Zhiling Tian
2024,53(10):2852-2859 DOI: 10.12442/j.issn.1002-185X.20230511
Abstract:Using Ni3Al+Cr3C2 mixed powder with different amounts of Cr3C2, laser cladding was carried out on 45 steel to prepare Ni3Al-based alloy cladding layer. By means of scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and wear tests, the content and average size of in situ-formed carbides under different amounts of Cr3C2 were calculated, and the effects of carbides on the microstructure, microhardness and wear resistance of Ni3Al-based alloy cladding layer were analyzed. The results indicate that the microstructure of the Ni3Al-based alloy cladding layer contains mainly Ni3Al matrix and in situ-formed Cr7C3 carbides. With the increase of Cr3C2 content, the proportion of in situ-formed carbides in cladding layer increases from 6.8% to 32.3%, the average size increases from 0.10μm to 0.78μm, and the microhardness of the cladding layer increases from 471HV to 609HV. When the content of Cr3C2 is 35%, the carbide particles are dispersed, and uniform wear is produced in the process of wear test, so that the wear less of cladding layer is as low as 0.19 mg, and the wear loss of the disk is relatively the lowest, about 1.23 mg. However, when the content of Cr3C2 is 45%, the carbide content is 32.3%, but the large size particles are mainly. In the process of wear test, the large particles of carbide fracture and spalling, which accelerates the wear of the disk.
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Xia Yu, Wei Chunbei, Lin Songsheng, Xiang Qingchun, Shi Qian
2024,53(10):2860-2872 DOI: 10.12442/j.issn.1002-185X.20240138
Abstract:Ni-Mo-P and Ni-Mo-P/(h)BN composite coatings were prepared on the surface of GH4169 nickel-based high-temperature alloy by chemical composite plating technology. The tribological behaviour of the coatings at different temperatures and the microstructures of the coatings after friction wear at different temperatures were investigated. The tribological properties of the coatings at room temperature, 300℃, 500℃ and 700℃ were investigated by utilising a ball-disc friction and wear test. The chemical composition and organisational structure of the plated layer following the friction test at different temperatures were analysed by scanning electron microscope, energy spectrometer and X-ray diffractometer. The mechanical properties of the coatings were characterised by microhardness tester and Rockwell indentation tester following tribological tests at different temperatures.The results demonstrate that the deposited Ni-Mo-P and Ni-Mo-P/(h)BN composite coatings are predominantly amorphous structure containing small amounts of nancrystalline. The coatings transformed from amorphous to nanocrystalline structure with the increase of the friction test temperature. As the friction test temperature is increased, the plating layer undergoes a transformation from an amorphous to a nanocrystalline structure, accompanied by an increase in crystallinity. At temperatures exceeding 500℃, the The precipitation of the Ni3P hard phase in the plating layer occurs concurrently with the oxidative volatilisation of the Mo and P elements, resulting in the formation of pores within the plating layer and a reduction in its densification. As the temperature increased, the hardness of the plated layer exhibited a fluctuating trend, initially rising and then declining. Concurrently, the bonding strength of the film base exhibited a gradual decline, progressing from an HF1 grade to an HF6 grade. As the test temperature increased, the abrasive wear and oxidation of the plating layer became more pronounced. The highest wear rate was observed at 500℃. However, further increases in temperature resulted in a reduction in friction at the interface, with the average coefficient of friction of the Ni-Mo-P plating layer decreasing from 1 to 0.60. The coefficient of friction of the Ni-Mo-P/(h)BN composite layer was reduced from 0.88 to 0.53, which improved the friction reduction and wear-resistant performance of the plating layer at high temperatures. The incorporation of (h)BN particles into the plating layer enhances the P content, thereby increasing the toughness of the Ni-Mo-P/(h)BN composite plating layer, improving the hardness of the composite plating layer, and strengthening the film-base bonding. Furthermore, the composite plating layer exhibits superior wear resistance within the temperature range of room temperature to 700℃.
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Yuan Haojie, Tian Xin, Liu Ying
2024,53(10):2873-2881 DOI: 10.12442/j.issn.1002-185X.20240187
Abstract:In order to enhance the high-temperature antioxidant protection provided by glass coating on titanium alloy, this study introduces the Ti3AlC2 reinforcing phase into pure glass coating slurry by ball milling method, and scrapes the slurry onto the surface of TC4 alloy and conducts antioxidant test. The results show that when 5 wt.% Ti3AlC2 (TAC5 coating) was added, the α-contamination layer thickness of the TC4 alloy substrate is minimized, measuring approximately 65.78 μm. In comparison to the pure glass coating under similar test conditions, the α-contamination layer thickness of the TAC5 coating is reduced by about one quarter. This reduction occurs as the Ti3AlC2 reinforcing phase reacts with the infiltrated oxygen in the coating, thereby diminishing contact between the substrate and oxygen and improving the coating’s ability to safeguard the TC4 alloy against oxidation at elevated temperatures.
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2024,53(10):2968-2974 DOI: 10.12442/j.issn.1002-185X.20230680
Abstract:Yb2Si2O7 and high entropy double silicate powders (Yb0.25Y0.25Lu0.25Er0.25)2Si2O7, (Yb0.2Y0.2Lu0.2Er0.2Sc0.2)2Si2O7, and (Yb0.2Y0.2Lu0.2Er0.2Ho0.2)2Si2O7 were prepared through solid-state reaction. The phase composition, thermal expansion coefficient, thermal conductivity, and elastic modulus of their ceramic blocks and insulation treatment were studied. The results show that due to the addition of rare earth elements Y, Lu, and Er, the thermal expansion coefficient and thermal conductivity of high entropy (Yb0.25Y0.25Lu0.25Er0.25)2Si2O7 are similar to those of Yb2Si2O7, but the elastic modulus decreases the least, at 10.28%; Due to the addition of Scelements, high entropy (Yb0.2Y0.2Lu0.2Er0.2Sc0.2)2Si2O7 has lower thermal expansion coefficient and thermal conductivity compared to (Yb0.25Y0.25Lu0.25Er0.25)2Si2O7, and the elastic modulus is reduced by 18.74%; Compared with (Yb0.25Y0.25Lu0.25Er0.25)2Si2O7, the high entropy (Yb0.2Y0.2Lu0.2Er0.2Ho0.2)2Si2O7 doped with Ho element has a higher thermal expansion coefficient and lower thermal conductivity, but its elastic modulus decreases the most, reaching 24.78%. After insulation at 1200 ℃ and 1300 ℃ for 10, 30, and 50 hours, Yb2Si2O7, (Yb0.25Y0.25Lu0.25Er0.25)2Si2O7, (Yb0.2Y0.2Lu0.2Er0.2Sc0.2)2Si2O7, and (Yb0.2Y0.2Lu0.2Er0.2Ho0.2)2Si2O7 all exhibited good high-temperature stability, and their elastic modulus increased with the increase of insulation time, while their thermal expansion coefficient gradually decreased. After high entropy double silicate insulation treatment, it still exhibits good high-temperature phase stability and has a similar coefficient of thermal expansion to the substrate, indicating that the prepared high entropy double silicate is suitable for thermal environment barrier coating materials of high thrust weight ratio aviation engines.
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Li Hushan, Ding Chaogang, Ding Ziheng, Zhang Hao, Wang Fanghui, Chen Yuxi, Bao Jianxing, Xu Jie, Guo Bin, Shan Debin
2024,53(10):2713-2717 DOI: 10.12442/j.issn.1002-185X.20240485
Abstract:The mechanical properties and fracture morphologies of Cu/Nb multilayer composites under electric-assisted tension (EAT) were investigated. Results show that the generated Joule-heat leads to obvious stress softening with the increase in current density. However, the elongation decreases, which is closely related to the characteristic fracture behavior of Cu/Nb multilayer composites during EAT. The fracture pattern is gradually transformed from ductile fracture to melt fracture with the increase in current density.
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Ren Penghe, Xiao Lairong, Cai Zhenyang, Tu Xiaoxuan, Zhao Xiaojun
2024,53(10):2718-2722 DOI: 10.12442/j.issn.1002-185X.20220918
Abstract:The dimensional change, residual stress, grain orientation difference, dislocation density, and dislocation distribution of beryllium after different hot isostatic pressing treatments were analyzed by laser length meter, Raman spectrometer, nanoindentation meter, electron backscattered diffractometer, and transmission electron microscope, and the influence of thermal-cold cycling treatment on the dimensional stability of beryllium was analyzed. Results show that the size of the hot isostatic pressed beryllium tends to be stable after 6 cycles of thermal-cold cycling treatment from -100 °C to 150 °C, and it has good dimensional stability. The dimensional stabilization mechanism of beryllium is mainly the homogenization of dislocations within the grain and the homogenization of orientation difference caused by micro-plastic deformation.
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Zhou Cheng, Jin Lei, Jing Gaoyang, Yu Boyan, Zhao Jun
2024,53(10):2786-2793 DOI: 10.12442/j.issn.1002-185X.20240244
Abstract:The coarsening behavior of γ? precipitate phase at different temperatures and the compressive performance of novel Co-Ni-Al-W superalloy were investigated. Experiment results show that the evolution of the mean radius and volume fraction of the γ? phase obeys the classical Lifshitz-Slyozov-Wagner model. The coarsening rate of the γ? phase exhibits a significant dependence on the aging temperature, which increases from 1.30×10-27 m3/s at 800 °C to 9.56×10-27 m3/s at 900 °C. The activation energy of γ? phase is mainly influenced by the W diffusion in the γ matrix, presenting as 210 kJ/mol. The prepared Co-Ni-Al-W alloy possesses superb comprehensive properties, particularly the good combination of high γ? solvus temperature (1221 °C) and low density (8.7 g/cm3). Besides, the compressive yield strength of the Co-Ni-Al-W alloy at ambient and high temperatures are higher than that of other γ?-strengthened Co-based superalloys. The compressive yield strength of the Co-Ni-Al-W alloy at 850 °C is as high as 774 MPa.
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Zhang Yuezhong, Chen Xiaoting, Shen Jing, Wu Pengpeng, Zhang Shaohua, Liu Baosheng
2024,53(10):2794-2804 DOI: 10.12442/j.issn.1002-185X.20240299
Abstract:The microstructure and corrosion behaviour of hot-rolled Mg-3Zn-1Y-xCu alloys (x=0, 1, 3, 5, wt%) were investigated. Results show that all Mg-3Zn-1Y-xCu alloys mainly consist of α-Mg matrix and Mg3Zn6Y phases. The addition of Cu element promotes the formation of MgZnCu phase, and the amount of MgZnCu phase is increased with the increase in Cu content. Electrochemical and immersion test results show that the corrosion resistance of Mg-3Zn-1Y-xCu alloys is deteriorated after Cu addition, which can be attributed to the influence of the microstructure of alloys and the properties of the formed corrosion product film. The MgZnCu phase with high electrochemical potential accelerates the micro-galvanic corrosion as strong cathodic sites, and the decreased protection effect of the corrosion product ?lm results from the variation in PBR value of the related compounds.
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Zhang Yingying, Wang Xuebing, Xiong Ning, Liu Xuequan
2024,53(10):2882-2890 DOI: 10.12442/j.issn.1002-185X.20240088
Abstract:The W-25Re alloy was prepared by selective laser melting (SLM) using spherical W-25Re (mass fraction, %, hereinafter) alloy powder as the raw material. The effects of process parameters on the relative density, microstructure and micro-Vickers hardness of W-25Re alloy were investigated. The relative density, microstructure, phase composition, and micro-Vickers hardness of W-25Re alloy were characterized by analytical balance, field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), microhardness tester. The results show that there are no obvious spheroidization, warping, deformation, delamination or non-forming phenomena during the preparation of W-25Re alloy by SLM. There are no obvious defects such as holes and cracks on the surface and side of the specimens, and W-25Re alloy formability is good. With the increase of Ev, the grain morphology in the vertical plane of W-25Re alloy specimens gradually changes from the mixture of equiaxed and columnar grains to coarse columnar grains. W-25Re alloy specimens only contain the cubic W13Re7 phase, and the change in the leftward shift of the diffraction peak 2θ angle is mainly caused by residual stress during the forming process. The influence of laser power and scanning speed on the relative densityof W-25Re alloy is significant. When Ev is 1050 J/mm3, that is, the laser power is 210 W and the scanning speed is 200 mm/s, the W-25Re alloy specimen with a relative density of up to 98.49% can be obtained. At this time, the microhardness of the specimen in the horizontal and the vertical plane is as high as 525.9 HV0.2 and 520.6 HV0.2, respectively, which is close to the hardness value of the rolled W-25Re alloy.
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Wang Xianjun, Yang Junzhou, Wang Shichen, Wang Zhixuan, Hu Boliang, Wang Li, Bai Run, Gao Xuanqiao, Zhang Wen, Hu Ping
2024,53(10):2891-2896 DOI: 10.12442/j.issn.1002-185X.20230509
Abstract:The constant strain rate compression experiments were conducted on Mo-14Re alloy by the Gleeble-3500 thermal simulation testing machine, the high-temperature were selected at 1400℃, 1500℃, 1600℃, and strain rates of 0.01 s-1, 0.1 s-1, 1 s-1, and 10 s-1.During the hot deformation process, the flow stress decreases with the increase of deformation temperature and the decrease of strain rate, which is due to the relative effect of work hardening and dynamic softening under different conditions. Based on the Arrhenius model and Zener Hollomon function, a constitutive equation for the flow stress of Mo-14Re alloy was established, and the activation energy for hot deformation of Mo-14Re alloy was obtained to be 588.31 kJ . mol-1. According to the established Hot processing map, the reasonable forming process parameters of Mo-14Re alloy are that the temperature is 1400℃~1600℃, the strain rate is 0.0089~0.14s-1, and the power dissipation coefficient Not less than 0.22, which is a reasonable process parameter for Mo-14Re alloy.
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Yin Tao, Wang Baojian, Hu Zhongwu, Zhang Weiwei, Bai Wei, Ren Guangpeng, Guo Linjiang, Liu Yan, Zhang Wen, li jianfeng
2024,53(10):2897-2905 DOI: 10.12442/j.issn.1002-185X.20240190
Abstract:Mo-based single crystal is a key material for nuclear power generation components in deep space exploration ships. Optimizing alloy composition is an important way to the applied property improvement of single crystal materials, and also can improve the power generation efficiency and service life of nuclear power sources. In this paper, a novel Mo-Nb-W single crystal was prepared by electron beam suspension zone melting method, and the hardness (H), contact stiffness (S) and elastic modulus (E) in the (110), (111) and (112) orientation crystal planes were investigated by nanoindentation technology. The results showed that there was no pop-in phenomenon in the load-displacement (P-h) curves of the (111) crystal plane, while the pop-in step appeared in the P-h curves of both (110) and (112) crystal plane during nanoindentation. The hardness in the measured oriented crystal planes gradually gone up with the increase of strain rate due to the shortened relaxation time, while the contact stiffness and elastic modulus slowly decreased as strain rate increased. There was significant anisotropy in the mechanical properties of Mo-Nb-W single crystal, and the hardness ranked: H(111)>H(110)>H(112), while the order of contact stiffness and elastic modulus were as follow: S(111)>S(112)>S(110) and E(111)>E(112)>E(110). The hardness in these mentioned orientation crystal planes gradually decreased with the rising of indentation depth, and the (111) oriented crystal plane had the most obvious indentation size effect.
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Wang Rongshan, Jia Xingna, Zhou Qian, Zhang Yanwei, Bai Guanghai, Xu Chi, Xue Wenbin
2024,53(10):2906-2912 DOI: 10.12442/j.issn.1002-185X.20230531
Abstract:Zirconium alloys are used as fuel cladding materials in commercial reactors, which suffer from synergetic effects of irradiation and corrosion degradations. In order to evaluate the effects of irradiation on the corrosion behavior of the Zr-1Nb alloy, the alloy has been irradiated with 6.37 MeV Xe ions. The pre- and post-irradiation corrosion property modifications have been evaluated. The current paper have also reported the micro-hardness, surface roughness and phase composition modifications. After the Xe ion irradiation, unraveling surface has been observed due to the ion sputtering effect. The surface roughness and the microhardness are increased with increasing irradiation dose. The post-irradiation corrosion under LiOH solution result with lath shaped surface microstructures on the Zr-1Nb samples, which become more pronounced at higher irradiation doses. The polarization current density for the 0.5 dpa dose irradiated sample is increased by 18 times over that of the unirradiated sample, while it is about 72 times for the 2.7 dpa irradiated sample. After the ion irradiation tests, the polarization potentials are lowered (increased negatively) and the polarization resistance values are increased, compared with the unirradiated sample. The electro-chemical impedance spectra (EIS) results show that, the lower-frequency impedance values are decreased, the curvature radius of the capacitance curve is decreased and the phase angle peak is moving rightward with increasing irradiation doses. The polarization curves and the EIS results show that the ion-irradiation has increased the corrosion tendency of the Zr-1Nb alloy, and its corrosion resistance is decreased with increasing irradiation doses. The reduced corrosion resistance after the ion irradiation tests are considered to be mainly caused by the irradiation induced damages on the alloy matrix material.
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liuyingjie, hu qiang, zhaoxinming, zhangshaoming
2024,53(10):2913-2925 DOI: 10.12442/j.issn.1002-185X.20230508
Abstract:Numerical simulation and experimental verification were used to study the atomization process of aluminum alloy powder by rotating disk, systematically study the spreading motion characteristics of melt on different disk surfaces, the breaking law of melt thin liquid film, and the flight cooling of droplets formed after crushing. The results showed that: The slip of liquid film on the surface of the spherical disk is smaller, the liquid film spreads more evenly, and the heat transfer of the disk is more stable. Under the same working conditions, the continuous liquid film boundary diameter of the spherical disk increases by about 40%, the maximum liquid film velocity increases by about 19%, the median diameter D50 of atomized droplets decreases by about 14%, and the droplet size distribution is more concentrated, the control of particle size and particle size distribution is more efficient.
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zhangwei, chengdazhao, liucaiyan, macong, wulu, zhangjing
2024,53(10):2926-2933 DOI: 10.12442/j.issn.1002-185X.20230525
Abstract:Nuclear materials are exposed to high temperature, high pressure and strong irradiation for a long time, and are subjected to strong neutron irradiation, which will produce a large number of point defects under the action of cascade collision, and then form radiation voids. Irradiation swelling caused by irradiation voids is responsible for the failure of austenite steel serve in the reactor core. The external stress introduced in the process of material processing and service and the elastic stress field generated by crystal defects such as dislocation have an important influence on diffusion and phase transformation. The phase field method at mesoscale can not only couple the physical fields such as temperature, irradiation and stress, but also simulate the dynamics and morphology evolution of the microstructure of materials during irradiation. A mesoscale phase field model coupled with rate and micro-elastic theory is used to survey the stress effects on void microstructures for Fe-Cr austenite; the global applied stress and the local dislocation stress field are considered. The applied stress promotes vacancies aggregate, nucleate, and growth, and the voids evolve into fusiform eventually. Voids in the stressed state have a larger size and lower density compared with a stress-free state. The larger the applied stress, the larger the average size and volume fraction, the smaller the number, and the more significant the morphology reconstruction is. The local elastic stress field of dislocation absorbs vacancies to reduce the elastic energy, and the concentrated vacancies accelerate the voids preferentially nucleate and grow around the dislocation. Compared with the dislocation-free system, the voids are fine and denser when dislocations exist; but the volume fraction and the morphologies of voids persist. In contrast, the applied stress should probably cause server swelling than dislocations in Fe-Cr alloys. The studying benefits the properties evaluation of in-core reactor components.
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Ma Zhijun, Hang Wenwu, Weng Xingyuan, Gao Jing, Zheng Yunsheng, Tao Honglin
2024,53(10):2934-2940 DOI: 10.12442/j.issn.1002-185X.20230513
Abstract:Spinel MgxCo1-xFe2O4 was prepared by hydrothermal method. The effects of the proportion of Mg and Co doping on the crystal structure, microstructure and absorption properties of magnesia cobalt ferrite were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vector network analyzer (VNA). The electromagnetic wave absorption mechanism of magnesia cobalt ferrite was summarized. The results show that under the conditions of pH=10, crystallization temperature 180℃ and crystallization time 8 h, Mg-Co ferrite with irregular quadrilateral morphology was successfully prepared. When the ratio of Mg2+ and Co2+ is 5:5 and the thickness of the absorbing layer is 3.5mm, the reflection loss value at the frequency 9.50 GHz reaches -40.78 dB, and the effective absorption frequency band is 3.65 GHz (8.06~11.71 GHz), covering the X-band. The excellent absorbing properties are attributed to the combined action of natural resonance, exchange resonance and eddy current loss.
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Wang Zhuang, Shiyilei, Sang Xinghua, Xu Haiying, Yang Guang, Yang Bo, Qi Bojin
2024,53(10):2941-2951 DOI: 10.12442/j.issn.1002-185X.20230524
Abstract:The presence of needle α′ martensite in the coarse columnar β grains is the main reason for the poor ductility of TC11 titanium alloys for wire-fed electron beam additive manufacturing (EBAM). In order to achieve the engineering fabrication of high-strength and ductile TC11 titanium alloy, a novel coaxial electron beam wire additive manufacturing (C-EBAM) process was used to improve the interaction state of electron beam, wire, and substrate during the EBAM process, and to improve the heat distribution of the melt pool. A detailed comparison between EBAM and C-EBAM was further made in terms of microstructure, grain morphology and mechanical properties. The effects of the transition state of the wire on the process stability, the martensitic transformation process, and the reasons for the difference and anisotropy of the tensile properties were discussed. The results show that C-EBAM achieves a strong lamellar α+β microstructure with almost no evaporation of Al elements via the pathway of slow cooling of the β phase field and in situ martensite decomposition at a lower cooling rate. Compared to EBAM, the improvement in ductility of C-EBAM can be attributed to a bi-lamellar microstructure and discontinuous grain boundaries α. This indicates the direction for further optimization of the beam source characteristics.
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Xiaopeng Li, Youshui Xie, Yao Huang, Yihan Zhao, Yanwen Sun, Chengzhi Zhao, Hexin Zhang
2024,53(10):2952-2959 DOI: 10.12442/j.issn.1002-185X.20230527
Abstract:In this paper the effects of different cooling speeds on the organization evolution of second-generation nickel-based single-crystal superalloy DD6 are revealed by high-resolution transmission electron microscopy and scanning electron microscopy. Under air-cooling conditions, a large number of secondary γ" precipitates are distributed at the matrix channels, and the secondary γ" precipitates progressively evolve in shape from spherical to cuboidal and then to butterfly-like shapes, and the size also increases with time; sharp crevices appear at the edges of the γ" precipitates and gradually evolve into serrated grooves. Under furnace-cooling conditions, a large number of fine spherical secondary γ" precipitates are distributed in the collective channel, and the width of the matrix channel increased and is positively correlated with the holding time. Under water-cooling conditions, there is no secondary γ" precipitates distribution in the matrix channel, the cubicity of γ" precipitates is complete, and there is no significant change in morphology with the extension of the holding time. γ" precipitates produces a large number of positive-negative edge-type dislocations between the two-phase interfaces in the process of selective decomposition, and the positive-negative edge-type dislocations on the two sides of the phase boundary meet to produce annihilation, reduce the surrounding energy, and promote the selective decomposition of the γ" precipitates.
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Chenxi Ma, Rong Li, Wei Wu, Huang Hui, Dai Zhao, Wang Ze zhong, Zhou Li
2024,53(10):2960-2967 DOI: 10.12442/j.issn.1002-185X.20230528
Abstract:In this paper, the effect of Cu content on the tensile properties of Al-Si-Mg-Er-Zr alloy at room temperature and high temperature was studied. They were α-Al, Si, β, Q and θ phases in the as-cast Al-Si-Mg-Er-Zr alloys with different Cu contents. With the increase of Cu content, the eutectic microstructure of the alloy increases, and it is bone-shaped, which is conducive to improving the casting performance of the alloy. With the increase of Cu content, the yield strength of as-cast alloys increases. Three Al-Si-Mg-Er-Zr alloys with different Cu content (0.6Cu, 1.0Cu and 1.0Cu) were heat treated under 500°C/4h+540°C/2h+180°C/xh, and they reached peak aging at 10h, 12h and 12h, respectively, and the peak hardness was 137.2HV, 139.2HV and 142.7HV, respectively. With the increase of Cu content, the room temperature tensile strength of the alloys under T6 temper increases, which is due to the fact that the alloy containing 1.4Cu has the most strengthening phase, including β ? ? phase, Q ? phase and θ ? phase. After 44 hours of soaking at 300°C, the hardness of the alloy containing 1.4Cu decreased the least, this is because, at 300 ℃,with the increase of the Cu level, the amount of the Q-Al5Mg8Cu2Si6 precipitates increases, and the Q-Al5Mg8Cu2Si6 phase is the main thermo-dynamically stable precipitate at 300 ℃ and improved the heat resistance of the alloy. The elongation at 300°C of the three Cu alloys under T6 temper was higher than that of room temperature tensile, and the fracture form also changed from brittle fracture at room temperature to ductile fracture at 300℃.
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Xia Zhiwen, Lv Junyi, Li Tao, Li Yage, Zhang Haijun
2024,53(10):2975-2986 DOI: 10.12442/j.issn.1002-185X.20230505
Abstract:2D materials are widely used in optics, biology, materials science and semiconductor fields owing to their large specific surface area, high carrier mobility and high thermal conductivity. Mechanical ball milling method is widely used in the stripping of 2D materials because of its advantages of low cost, environmental protection, and large-scale production. Starting from the mechanism and related models of mechanical ball milling, this paper reviews the research status of nanosheets of 2D materials, such as graphene, boron nitride, molybdenum disulfide and so on, by mechanical ball milling. The advantages and existing problems of this method in preparing 2D nanomaterials were summarized, and the development directions of 2D materials prepared by mechanical ball milling were prospected.
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Li Hongpeng, Pi Xiaolin, Ni Wenruo, Tian Yiran, Tong Yingcheng, Yuan Tengrui, Zhang Zhenqiang
2024,53(10):2987-3000 DOI: 10.12442/j.issn.1002-185X.20230518
Abstract:Proton exchange membrane fuel cells (PEMFCs) are potential solutions for the dual problems of energy shortage and environmental pollution, due to their high efficiency, low temperature, and eco-friendliness. However, the slow kinetic process in its cathodic oxygen reduction reaction (ORR) has to rely on scarce and expensive Pt-based catalysts, which hinders the further development and application of PEMFC technology. In order to reduce the cost and ensure efficient catalytic performance, researchers have developed various technological strategies in recent years, and alloying with Pt through the introduction of transition metals is one of the main strategies, especially PtCo bimetallic catalysts, which exhibit superior ORR catalytic performance. This paper reviews the research results and current status of PtCo alloy catalysts for PEMFCs in recent years. Firstly, it summarizes the effects of modulation strategies such as catalyst component control, particle size modulation, crystal surface modulation, and doping on the catalytic activity of fuel cells. Then, it introduces the most promising PtCo alloy structures, such as polyhedral, core-shells, nano-frames, and ordered intermetallic structure, etc. It also discusses the research on catalyst supports. Finally, it identifies the existing challenges and future prospects of PtCo alloy catalysts for their applications.
2024,Volume 53, Issue 10
>Special Issue:surface treatment technology
>Research Letters
>Materials Science
>Reviews
- Published Issue
- Call for Papers
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Zhi Hui, Hou Jinxiong, Ma Shengguo, Wang Tao, Wang Zhihua, Huang Qingxue
Available online:October 16, 2024 DOI: 10.12442/j.issn.1002-185X.20240515
Abstract:The conventional macro forming technology is ineffective for the micro forming process due to the influence of the size effect, which exhibits a close tie with the thickness-to-diameter (t/d) ratio during the thin sheet forming process. The purpose of this paper is to establish a constitutive model that considering the size effect in different deformation stages of CoCrNi medium entropy alloy strip during the uniaxial quasi-static tensile test. The results show that when the value of t/d is less than 10.62, its properties have a significant size dependence in the elastic stage of CoCrNi alloy strip. With the decrease of t/d, the volume fraction of the surface layer grains increases, and the flow stress decreases linearly. In the plastic stage, the stiffness of the material is correlated with the t/d ratio. Initially, as the t/d ratio increases, so does the work-hardening capacity of the material, reaching a maximum when the t/d ratio is approximately 10, after which it begins to decline.
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Li xiang, Li Hong Ying, tian yu xing, Cao Hai Long, Niu Guan Mei, Wang Yan, Rao Mao, Han Jia Qiang, Liu Cheng, Zheng Zi Qiao
Available online:August 06, 2024 DOI: 10.12442/j.issn.1002-185X.20240282
Abstract:A corresponding relationship was established between grain structure evolution, extrusion simulation and profile fabrication, and the grain structure was optimized for extrusion profile with typical section of 2196 Al-Li alloy. The results show that the alloy exhibits excellent hot deformability at a relative wide parameters range. The dominate mechanism of microstructure evolution is dynamic recovery, although some localized dynamic recrystallization is also observed, caused by strain concentration under a couple of lower temperature (350℃, 400℃) and higher strain rate of 10 s-1. Compared to experimental compression deformation, the larger strain promotes dynamic recrystalliztion during extrusion process, and the differences of deformation conditions on profile section lead to non-homogeneous grain structure. Based on the equipment capability, a deformation condition that temperature 430~440℃ and strain rate of 0.005~0.95s-1 on profile section is suggested to obtain relatively uniform microstructure, the lower fraction of recrystallization and abundant sub-grain structure, which is benefit for the strength and toughness matching.
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Zhencen Zhu, Xiaoqiang Li, Cunliang Pan, Shengguan Qu
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240089
Abstract:This article refers to the composition of MA754 alloy and prepared Ni-based alloy powders with high melting point containing Ti and Nb as framework, as well as low melting point Ni-based alloy powders with B and Zr as wetting agents by high-energy ball milling, respectively. A Ni-based ODS alloy with excellent performance was prepared by the way of spark plasma sintering after mixing two kinds of powder in the optimal ratio. The influence of sintering temperature and the content of low melting point powder in composite powder on the microstructure and mechanical properties of the alloy was studied. The results showed that dispersed oxides could be observed in the alloy structure prepared by this method, and the mechanical properties were improved compared to MA754 alloy. As the content of low melting point alloy in the composite powder increases, the alloy structure first becomes small and uniform, then acicular aggregate phases and coarse block phases appear. The tensile strength of the alloy shows a trend of first increasing and then decreasing. When the sintering temperature is 1025 ℃ and the content of low melting point alloy powder in the composite powder is 3 wt.%, the alloy has the highest tensile strength of 951.87 MPa, which is significantly improved compared to commercial MA754 alloy.
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Sun Yetao, Feng Jietao, Yin Jiaxin, Wang Rong, Wang Deqing, Li Chengjun, Wang Yingmin, Fang Canfeng
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240098
Abstract:In order to investigate the effect of Be on the transformation of Fe-containing phases during solution treatment, a series of experiments combining Be with different solution treatment processes were designed, and the intrinsic relationship between its effect on the morphology of eutectic silicon and Fe-containing phases and the mechanical properties was deeply studied, aiming to comprehensively improve the overall performance of the hypoeutectic Al-Si-Mg alloy. The results showed that Be delayed the decomposition of Mg2Si phase and promoted the transformation of π-AlSiMgFe phase to β-AlFeSi phase. The accelerated transformation of the morphology of the π-AlSiMgFe phase structure not only enhanced the strengthening effect, but also weakened the cleavage effect of the π-AlSiMgFe phase on the matrix, thus synchronously improving the strength and plasticity of the alloy.
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Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240104
Abstract:Using high-purity tungsten powder and amorphous boron powder as raw materials, high-purity W2B alloy powder was efficiently synthesized at low temperatures by mechanical activation and combination reactions. The effects of mechanical activation time on the morphology, particle size distribution, and specific surface area of the powders were investigated, and the relationship between phase composition, synthesis temperature, and reaction mechanism was elucidated. The results indicated that mechanical activation could effectively refine the particles, and the surface area and dislocation density of the powder increased as the mechanical activation time lengthened. The content of the W2B phase in the reaction-synthesized powder increased as the mechanical activation time increased. After 20 hours of mechanical activation, the true density of the reaction-synthesized powder reached 17.01 g/cm3, with the W2B phase content of 96 wt%. The powder synthesized by thatcontained 23 wt% more W2B phase compared to the powder without the mechanical activation reaction. During the synthesis reaction, the B atoms diffused into the W matrix, resulting in the formation of the low-density WB phase. Mechanical activation introduced a significant number of dislocation defects, which created a channel for atoms diffusion and accelerated the transformation of the WB phase to the W2B phase.
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lijuan, liuchang, wanglu, lidongting, zhouliyu, liuying
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240108
Abstract:In order to improve the hardness and wear resistance of titanium (Ti), in this paper, it is proposed to introduce TiB2 hard phase into pure titanium (Ti), accurately control the reaction process of the two based on the discharge plasma sintering (SPS) technology, and construct a TiB2-TiB-Ti "hard-core-strong-interface" structure in Ti matrix that inherits the diffusion path of B elements. Finally, at 40% TiB2 addition, a high hardness of 863.5 HV5 at room temperature and 720.9 HV5 at 400℃ in the middle and high temperatures is obtained, which makes its friction performance better than that of commercial TC4 high-temperature titanium alloys under the same friction conditions in the temperature range from room temperature to 400℃. At the same time, thanks to its excellent bonding interface, the alloy also exhibits unique high-temperature and high-toughness properties, maintaining a high compressive strength of 1120 MPa and compression of more than 10% at 400℃. The design concept of this study is inspirational and useful. The design idea of this study is inspiring and universal, which is expected to provide a new method for the research and development of new medium-high-temperature and high-toughness wear-resistant titanium alloys, and to promote the application of related materials in aerospace field.
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Wang Chunhui, Yang Guangyu, Qin He, Kan Zhiyong
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240112
Abstract:The I phase (Mg3GdZn6, icosahedral quasicrystal phase) is widely considered as the strengthening phase in Mg-Zn-Gd system alloys, offering more significant improvements in the mechanical properties compared to the W phase (Mg3Gd2Zn3, cubic phase). However, both the W phase and the I phase typically coexist in the as-cast Mg-Zn-Gd alloy, thereby weakening its mechanical properties. There has been limited systematic research dedicated to investigating the crystallization mechanism of these phases during solidification. In this study, the equilibrium solidification and Scheil solidification paths of Mg-xZn-2Gd (x = 0~12, wt.%) alloys were calculated using Thermo-Calc software. The effects of cooling rate and alloy composition on the fraction of the I phase were studied. The results show that the equilibrium solidification structure of the alloy with a Zn/Gd atomic ratio of 6.0 only contains the I phase. In contrast, limited solute diffusion in the solid phase hampers the transformation of the W phase into the I phase during non-equilibrium solidification, forming a mixed structure composed of both the W phase and the I phase. The variation of cooling rate and alloy composition affects the solute enrichment rate in the Liquid during the solidification process of the primary α-Mg phase, alters the solute content and temperature of the residual Liquid when the secondary phase begins to crystallize, and influences the type and fraction of the secondary phase as determined by the solidification driving force. Higher solidification cooling rates and an increased Zn/Gd atomic ratio inhibit the W phase and promote the formation of the I phase during Mg-Zn-Gd alloy preparation, resulting in the alloy with a higher proportion of the I phase.
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Luan Lijun, Xu Changyan, Zhang Ziqiu, Xie Haichen
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240113
Abstract:The garnet type CexY3-xFe5O12 doped with Ce3+ was prepared by an optimized sol-gel method (x = 0, 0.1, 0.2, 0.3; Ce:YIG) crystal, the optimal solution is to obtain crystals with no derived impurities and high magneto-optical properties by pre-sintering and sintering in a wide temperature range of 900-1400 ℃. Thermogravimetric analysis was used to determine the synthesis temperature of the crystal at 890 ℃. XRD results show that the crystal lattice constant varies from 12.37241 ? to 12.4121 ?, and the impurity phase CeO2 appears when Ce > 0.2. SEM analysis shows that the grain size of Ce:YIG increases with the increase of sintering temperature and Ce3+ content, and its size distribution ranges from 0.257 to 6.52 mm, which is the maximum size of YIG crystal obtained at present. All Ce: YIG samples were ferromagnetic at room temperature, with saturation magnetization varying from 23.47 to 28.10 emu/g. The permeability of Ce0.1Y2.9Fe5O12 crystal sintered at 1200 ~1300 ℃ is as high as 3.68 ~ 3.90. According to the relationship between Faraday rotation Angle and permeability, the crystal sintered in this temperature range is likely to obtain the best Faraday rotation performance.
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CHEN Jianbo, YANG Xiaojiao, YANG Ningjia, NIU Yibo, OUYANG Linfeng, Ying Liu
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240114
Abstract:Kilogram-scale micro-nano SrVO3 powder was produced with the sol-gel method combined with hydrogen reduction and heat treatment. Then SrVO3 bulks were prepared by cold pressing and sintering the sifted powders using different mesh sizes (unsifted powder, 100 mesh, 200 mesh, and 300 mesh). The thermal stability of SrVO3 powder and bulks under air was investigated, and the effects of powder granularity sifting on granularity and distribution of their raw material, bulk grain size, and electrical conductivity were also evaluated. The results show that: SrVO3 bulk has better thermal stability in air than SrVO3 powder; the temperature at which oxidative weight increase occurs is enhanced from 335 °C for the powder to 430 °C for the bulk. The mean particle size of the raw material powders decreases, the electrical conductivity of the related cold-pressing sintering bulks is significantly raised, and the conductivity of the powders rises with increasing granularity sifting mesh. Granularity sifting can be used to acquire smaller and more uniform powder raw materials, which will increase the density of the bulks produced by cold-pressing sintering. Furthermore, the material’s more effective routes for the conduction of electric charge are established and the conductivity of the prepared SrVO3 bulk reaches 20,000 S/cm, which is 37% higher than that of the bulk produced by unsifted powder. Granularity sifting is essentially the optimization of the raw material’s particle size. More sifting of the SrVO3 powder’s particle size is expected to yield improved bulk material performance, providing the foundation for its use in transparent conductive films, semiconductor devices, sensors, and other areas.
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Research on thermal deformation characteristics of diffusion-bonded interface region in GH4169 alloy
Xu Qinsi, Zhang Mingchuan, Liu Yi, Cai Yusheng, Mu Yiqiang, 任德春, Ji Haibin, Lei Jiafeng
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240118
Abstract:The "bond line" of the diffusion bonding interface is a common characteristic of the diffusion-bonded region in nickel-based superalloys. It significantly impacts the performance of the diffusion joint. Thermal deformation machining is an effective method to improve the microstructure and properties of a diffusion bonding interface. In this study, the thermal deformation behavior of the GH4169 alloy diffusion-bonded region was investigated at a deformation temperature of 1213~1333 K with a strain rate of 0.01~10 s-1 using a Gleeble 3800 thermal-mechanical simulation test machine. The results show that the "bond line" in the diffusion bonding region of GH4169 alloy can be effectively eliminated through thermal deformation. The evolution of the δ phase in the diffusion bonding interface region is affected by deformation conditions. When the deformation temperature is lower than the solution temperature of the δ phase, the residual spheroidized δ phase prevents the growth of recrystallization nucleation grains and affects the subsequent recrystallization process. The spheroidization degree of the δ phase can be enhanced by reducing the strain rate. When the deformation temperature exceeds the dissolution temperature of the δ phase, the dissolution of the δ phase creates an extra driving force for recrystallization, thereby significantly enhancing the extent of recrystallization. A hyperbolic sinusoidal Arrhenius constitutive equation, incorporating strain compensation, is used to describe the correlation between flow stress and deformation conditions in the diffusion-bonded region of the GH4169 alloy. The calculated values of the constitutive equation agree with the experimental values. According to the dynamic model of the GH4169 alloy diffusion bonded region, the optimal processing parameters have been determined. The deformation temperature is 1310~1333 K, and the strain rate is 0.01~0.05 s-1.
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lujianqiang, wanglinlin, oumeiqiong, houkunlei, wangmin, wangping, mayingche
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240125
Abstract:As the thrust-to-weight ratio of the aero-engine increases, the turbine inlet temperature increases significantly, leading to a significant increase in the service temperature of other key hot-end components. In the process of service, nickel-based superalloys need to withstand the combined effect of high temperature, stress and environment, and the alloy surface will inevitably occur high temperature oxidation. High temperature oxidation often preferentially penetrates along grain boundaries, resulting in micro-voids and micro-cracks at grain boundaries, which seriously affects the properties of the alloy. Therefore, it is necessary to explore ways to improve the oxidation resistance of alloys at high temperatures. In this work, the effect of Hf on oxidation behavior of K4800 nickel-based superalloy was studied. The results show that the oxidation weight gain of K4800 and K4800+0.25Hf alloys increases with the extension of exposure time during static oxidation at 800℃ and 850℃, and the oxidation kinetics curves follow the parabola rule. However, the initial static oxidation rate of K4800+0.25Hf alloy (0.0265 g/m2·h at 800°C for 20 h and 0.0617 g/m2·h at 850°C for 20h) is lower than that of K4800 alloy (0.041 g/m2·h at 800°C and 0.0669 g/m2·h at 850°C). The oxide layer of the two experimental alloys comprises an outer oxide layer and an inner oxide layer.The outer oxide layer primarily consists of dense Cr2O3, while the inner oxide layer mainly contains dendritic Al2O3. However, with the Hf content increasing from 0 wt.% to 0.25 wt.%, the thickness of the Cr2O3 outer oxide layer decreases from 2.71 μm to 2.17 μm after oxidation at 800°C for 1000 h and from 5.83 μm to 4.09 μm after oxidation at 850°C for 1000 h.The results of EPMA analysis indicate the formation of HfO2 at the grain boundary of the oxide layer in the K4800+0.25Hf alloy, promoting the formation of Al2O3 around HfO2 and accelerating the growth of Al2O3. The presence of Al2O3 and HfO2 at the grain boundary contributes to reducing the outward diffusion rate of Cr3+ and delaying the thickening of the Cr2O3 oxide layer. Consequently, the addition of Hf enhances the oxidation resistance of the K4800 alloy.
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GuoShuGuo, LiuQuan, JiaZheng, KouRongHui, LiuxuDong
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240131
Abstract:In this paper, The effect of Y on the homogenization of Mg-6Zn-0.25Ca in terms of corrosion resistance was studied. The microstructure and corrosion resistance of the homogenized Mg-6Zn-0.25Ca and Mg-6Zn-1Y-0.25Ca alloys were investigated by XRD, OM, SEM, weight loss, hydrogen evolution and polarization curve experiments. The results show that the second phase of the homogeneous Mg-6Zn-0.25Ca alloy is Mg2Ca, and the average grain size increases slightly after the addition of Y element, the Mg2Ca phase decreases, and new second phases Mg12ZnY and Mg3Y2Zn3 are generated, and the volume fraction of the second phase increases and the distribution is more uniform. This results in the formation of a denser and more compact corrosion film on the magnesium matrix in the corrosion test, which can act as a barrier, and the newly formed Mg12ZnY and Mg3Y2Zn3 are distributed near the grain boundary or between the branches, and the electrochemical performance is low. These results reduce the hydrogen precipitation of Mg-6Zn-0.25Ca alloy in 3.5% NaCl solution, increase the self-corrosion potential of Mg-6Zn-0.25Ca alloy by increasing the Y element, and reduces self-corrosive current density. These improve the corrosion resistance of homogeneous Mg-6Zn-0.25Ca alloys. Therefore, the corrosion resistance of Mg-6Zn-1Y-0.25Ca alloy is much higher than that of Mg-6Zn-0.25Ca alloy.
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Liu Manping, Ma Hui, Cui Zhuang, Zeng Ying, Sun Shaochun, Zhao Guoping
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240133
Abstract:Ni-based single crystal superalloys have excellent comprehensive properties at high temperature, and are widely used in hot-end components such as blades of aero-engines and gas turbines. Fatigue failure is one of the main failure modes of blades in service. Based on the research status of fatigue behavior of Ni-based single crystal superalloys, the fatigue damage mechanism of Ni-based single crystal superalloys is reviewd in this paper. The effects of crystal orientation, temperature and loading mode on fatigue behavior are discussed, and the methods to optimize the fatigue life of Ni-based single crystal superalloys, such as optimizing composition, heat treatment and surface treatment, are introduced. Finally, the application of some advanced testing techniques, such as in-situ testing, in the study of fatigue behavior of Ni-based single crystal superalloys is proposed, and the development trend of fatigue behavior research of Ni-based single crystal superalloys is prospected.
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Wu Zhigang, Chen Tao, Liu Chunjiao
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240136
Abstract:The phase composition and microstructure of 27Cr44Ni5W3Al+MA ethylene cracking furnace tube were analyzed using XRD, OM, SEM and TEM. The results showed that the as-cast microstructures of the furnace tube were mainly composed of austenite matrix (γ phase) and fishbone multi-phase carbides on grain boundaries, the inside of the multi-phase carbides are lamellar M7C3, while the outside are blocky M23C6. In addition, two shapes of Ni3Al (γ" phases) were observed, namely the granular distributed near the junction between M23C6 and γ, and the blocky adjacent to M23C6. Both of M23C6 and granular γ" are the cube-on-cube orientation relationships with the γ matrix ([101]γ∥[101]M23C6,(-111)γ∥(-111)M23C6,(11-1)γ∥(11-1)M23C6;[1-12]γ∥[1-12]M23C6,(-111)γ∥(-111)M23C6,(220)γ∥(220)M23C6。[101]γ∥[101]γ",(-111)γ∥(-111)γ",(11-1)γ∥(11-1)γ";[1-12]γ∥[1-12]γ",(-111)γ∥(-111)γ",(220)γ∥(220)γ"). In addition, a large number of dislocations were observed in the as-cast microstructure, with sparse distribution away from M23C6 and dense distribution near M23C6. The precipitation mechanism of γ" and M23C6 during centrifugal casting was also discussed.
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wangyanjing, zhangwendong, xuzaidong, xurongzheng, mahuanchen, tangjinnong
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240139
Abstract:In this paper, an Al-8Zn-3Mg-1.05Cu alloy was designed according to the solid solubility of Zn, Mg and Cu elements in Al. The hot-rolled plate was subjected to solid solution treatment. The results of SEM and XRD showed that the solid solution structure with only a small amount of compound residue was obtained after solid solution treatment. Further cold rolling, annealing and aging treatment of the alloy were carried out. The EBSD results after cold rolling and annealing showed that the alloy obtained incompletely recrystallized structure after cold rolling and annealing. The KAM diagram showed that the dislocation density in the structure was high. The tensile properties of the alloy after annealing are fine, and the yield strength and elongation are 458.61 MPa and 15.6 %, respectively. The TEM results after aging treatment showed that a large number of fine MgZn2 phases were precipitated in the microstructure. The size of MgZn2 phase is small, and the average size is about 6.40 nm, which is smaller than the size of MgZn2 precipitates in the reported alloys. After aging, the alloy obtained ultra-high strength and good plasticity, the yield strength and elongation were 729 MPa and 10.37 % respectively. The strength composition of the alloy was calculated, and the precipitation strengthening contribution value of the fine MgZn2 phase was 348 MPa. The calculated yield strength value matched well with the experimental value.
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Pang Jie, Wang XiaoPeng, Xie Lei, Qiu Wenli, Zhou Junjie, Yue yue
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240148
Abstract:The solid surface icing issue has significant impacts on both industrial sectors and human life, hence exploring novel anti-icing materials is of great importance. In this study, PDMS with low surface energy was sprayed onto aluminum plates as a binder. Fe3O4 and Fe3O4/SiO2 dispersion liquids were separately sprayed to form photothermal hydrophobic coatings. Fe3O4 provides photothermal effects and has a certain rough structure. When SiO2 is added, the hydrophobicity is further enhanced, with a water contact angle reaching 155°. This coating greatly delays the icing time and accelerates frost melting. Under sunlight, the temperature rise can reach 71.8℃. The self-cleaning ability of this coating ensures it is not heavily polluted and possesses certain resistance to wind and sand impact, demonstrating good mechanical stability.
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Yang Bowei, Liu Wenyue, Gao Minqiang, Zhao Tan, Ren Yi, Li Tianyi, Guan Renguo
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240150
Abstract:As an important type of Al alloys with excellent comprehensive properties, Al–Mg alloys with excellent mechanical properties, good corrosion resistance, and weldability are widely used in aerospace, rail transit and marine ships. The recent research progress on the microstructure and property regulation of Al–Mg alloys during solidification, heat treatment, and plastic deformation at home and abroad was summarized, and the characteristic of each regulation method was analyzed. The application of continuous rheo-extrusion forming technology in the fabrication of Al–Mg alloys was emphatically introduced, and the future development direction of Al–Mg alloys was prospected.
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wangbingying, zhangkeke, fanyuchun, wujinna, guolimeng, wanghuigai, wangnannan
Available online:June 26, 2024 DOI: 10.12442/j.issn.1002-185X.20240154
Abstract:Dopamine polymerization reaction and hydrothermal method was used to prepare nickel coated alumina reinforcement phase; Preparation of nickel coated alumina (Ni/Al2O3) reinforced Sn1.0Ag0.5Cu (SAC105) composite material alloy using traditional casting method; The result showed that the nickel coating layer was continuous but with uneven thickness.The strength, toughness, and wettability of the SAC105 solder with the substrate have been im-proved, while the conductivity has not decreased significantly. The optimal doping amount was determined by comprehensive analysis when the doping amount of the reinforcing phase was 0.3wt%. The fracture mode of composite material alloy has shifted from a mixed mode of toughness and brittleness to a pure toughness fracture mode composed only of a large number of dimples.The prepared composite brazing material was made into solder paste for copper plate lap joint experiments. The maximum shear strength was achieved when the doping amount was 0.3wt% The growth index of IMC at the brazing interface of Ni/Al2O3 reinforced Sn1.0Ag0.5Cu composite brazing material was linearly fitted to n=0.39, which can be used to determine the joint effect of grain boundary diffusion and bulk diffusion on the growth of IMC at the interface
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Li Chong, Shi Hongjie, Sun Erju, Xu Yali, Xu Lingyu, Chen Chunyang, Sun Xiaoyi, Song Dejun
Available online:June 19, 2024 DOI: 10.12442/j.issn.1002-185X.20230792
Abstract:Large diameter Ti6321 alloy seamless tube with φ450*20mm was prepared using forging billet by cross piercing and hot rolling process, and the effect of annealing temperature on the microstructure and mechanical properties of seamless tube were investigated. The results show that the as-rolled tube microstructure is mainly composed of α phase and transformation β, equiaxial structure is obtained after annealing at 940℃, duplex structure is obtained after annealing at 970℃, widmanstatten structure obtained after annealing at 1020℃; With the annealing temperature increasing, the room temperature yield strength and tensile strength of the pipe will gradually decrease. The plasticity of the pipe will not change much below the transformation point, but will decrease sharply above the transformation point; the impact toughness first increased and then decreased. Comprehensive analysis shows that the suitable annealing temperature of the prepared large diameter Ti6321 seamless alloy pipe is about 970℃, and the pipe has the best impact performance and impact energy is 62J.In addition, the yield strength, tensile strength and elongation of the pipe after annealing at 970℃ are 786MPa, 878MPa and 16.25%, respectively.
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Meng Shuai-ju, Zhang Ming-chi, Wang Menglu, Song Jinlong, Zhang Chao-huan, Bi Guangli, Liu Haifeng, Jia Zhi
Available online:June 19, 2024 DOI: 10.12442/j.issn.1002-185X.20230815
Abstract:In order to reveal the effect of Zn on the microstructure and mechanical properties of Mg-Bi-Sn alloy, Mg-3Bi-5Sn-xZn (x= 0,1,2,3 wt.%) alloy was prepared by casting using OM, SEM, XRD, EPMA, Vickers hardness tester and tensile testing machine. The effect of Zn on the microstructure and mechanical properties of Mg-3Bi-5Sn (BT35) alloy was studied. The experimental results show that Zn can significantly refine the grain size of BT35 alloy. With the increase of Zn content, the grain size of BT35 alloy decreases significantly at first and then increases slightly, among which Mg-3Bi-5Sn-2Zn (BTZ352) alloy has the smallest grain size (58 μm). In addition, there are two kind of second phases, Mg3Bi2 and Mg2Sn, observed in BT35 alloy, and additional Mg2Zn phase and BiSn phase can be detected in the microstructure after adding Zn element. When the addition of Zn element is less than 3%, the tensile strength and elongation of the alloy firstly increase and then decrease slightly. Among them, BTZ352 alloy shows the best mechanical properties with the tensile strength and elongation of 263.5 ±6MPa and 13.2±0.6%, respectively; and the fracture microstructure of BTZ352 alloy exhibits typical transgranular fracture characteristics.
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