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Friction 2021年第5期9卷 1061-1076页

作者： Jinjuan CHENG Mincong MAO Xueping GAN Qian LEI Zhou LI Kechao ZHOU State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China School of Materials Science and Engineering Central South UniversityChangsha 410083China

Alloys used as bearings in aircraft landing gear are required to reduce friction and wear as well as improve the load‐carrying capability due to the increased aircraft ***–15Ni–8Sn–0.8Nb alloy is well known for possessing good mechanical and wear properties that satisfy such *** this study,the microstructure,mechanical properties,and grease‐lubricated sliding wear behavior of Cu–15Ni–8Sn–0.8Nb alloy with 0.8 wt%Nb are *** nanoscale NbNi3 and NbNi2Sn compounds can strengthen the alloy through the Orowan strengthening mechanism.A Stribeck‐like curve is plotted to illustrate the relationship among friction coefficient,normal load,and sliding velocity and to analyze the grease‐lubricated *** wear rate increases with normal load and decreases with sliding velocity,except at 2.58 m/s.A wear mechanism map has been developed to exhibit the dominant wear mechanisms under various friction *** the normal load is 700 N and the sliding velocity is 2.58 m/s,a chemical reaction between the lubricating grease and friction pairs occurs,resulting in the failure of lubricating grease and an increase in wear.

关键词： Cu–15Ni–8Sn–0.8Nb alloy microstructure mechanical properties grease‐lubricated wear behavior

An optimized hardness model for carburizing-quenching of low carbon alloy steel

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Journal of Central South University 2017年第1期24卷 9-16页

作者：张星唐进元张学瑞 State Key Laboratory of High Performance Complex Manufacturing Central South UniversityChangsha 410083China School of Software Central South UniversityChangsha 410083China

Research has been conducted about the hardness prediction for the carburizing and quenching process based on an optimized hardness simulation model,in accordance with the calculation rule of mixed *** coupling field model incorporates carburizing field analysis,temperature field analysis,phase transformation kinetics analysis and a modified hardness calculation *** determination of the calculation model for hardness,calculation equations are given to be applied to low carbon content(x(C)0.5%) in ***,the complete carburizing-quenching hardness calculation model is built,and the hardness simulation data are corrected considering the influence of residual austenite(RA) on *** simulations of the carburizing and quenching process of 17CrNiMo6 samples have been performed using DEFORM-HT_V10.2 and MATLAB R2013 ***,a series of comparisons of simulation results and measured values show a good agreement between them,which validates the accuracy of the proposed mathematical model.

关键词： carburizing-quenching simulation hardness model DEFORM-HT residual austenite high carbon content

The dynamic responses of lamellar and equiaxed nearβ-Ti alloys subjected to multi-pass cross rolling

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Journal of Materials Science & Technology 2020年第8期36卷 220-229页

作者： Wei Chen Hande Wang Y.C.Lin Xiaoyong Zhang Chao Chen Yaping Lv Kechao Zhou State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China

This work gives a comparison on the microstructural characteristics,textural discrepancies,and twinning behaviors of lamellar and equiaxed nearβ-Ti alloys during multi-pass cross rolling with a rolling reduction of 20%,50%and 80%.The results showed that the restoration mechanism of the alloy inβphase is strongly dependent on theαmorphologies,and in comparison,strain path has weaker influences on the grain refinement of theβ***,the texture intensities of bothαandβphases were weakened owing to the dynamic recrystallization(DRX)of the two phases in the equiaxed ***,with regard to the lamellar microstructure,dynamic recovery(DRV)of theβphase predominated,forming elongatedβ***,theαandβmatrix in lamellar microstructures obeyed the Burgers orientation relationship,which was gradually broken down until the final ***,the{1101}twinning exhibits a strong size *** the continuous DRX ofαphases,theα-twinning is suppressed owing to progressive grain *** activation ofβ-twinning,namely{332}?113?and{112}?111?,in nearβ-Ti alloys is heavily dependent on the deficientβ-stabilizing elements and the local stress *** findings provide an effective way to obtain ultra-fine grain microstructures of this alloy.

关键词： Nearβ-Ti alloys Multi-pass cross rolling Dynamic recrystallization {1101}Twinning β-twinning

Mechanochemical Dispersion of Nanodiamond Aggregates in Aqueous Media

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Journal of Materials Science & Technology 2005年第1期21卷 109-112页

作者： XiangyangXU YongweiZHU BaichunWANG ZhimingYU ShengzhongXIE R&DCenter ChangshaResearchInstituteofMiningandMetallurgyChangsha410012China SchoolofMaterialsScienceandEngineering CentralSouthUniversityChangsha410083China//R&DCenterChangshaResearchInstituteofMiningandMetallurgyChangsha410012China SchoolofMaterialsScienceandEngineering CentralSouthUniversityChangsha410083China

A technology of mechanochemical treatment (MCT) is introduced to modify nanodiamond (ND) surface aiming to obtaining a stable suspension with well-dispersed ND particles in aqueous medium. ND investigated in this paper is a purified product of nanometer-sized diamond synthesized by explosive detonation. As obvious aggregation and sediment were observed when the sample was added into deionized water, it is crucial to conduct deaggregation and dispersion investigations. Amid a series of mechanical treatments, i.e. grinding, stirring, ultrasonic and classification, some reagents are introduced to modify the newly created surface during aggregates comminution. For the co-effects of mechanical forces and surfactants, the mean size of particles was reduced and a stable system containing ND with narrow size distribution was prepared. Mechanism of surface reaction and modification are discussed, while AFM, Zetasizer3000HS, XRD, XPS and FTIR are utilized for the analysis. The functional chemical structure of ND particle surface and surface electrical property changed during the modification processes, and the dispersion character and stability of suspension can consequently be improved.

关键词： Aggregates Deaggregation Dispersion Mechanochemical treatment Nanodiamond

Coordination leaching of tungsten from scheelite concentrate with phosphorus in nitric acid

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Journal of Central South University 2016年第6期23卷 1312-1317页

作者：张文娟杨金洪赵中伟王文强李江涛 School of Metallurgy and Environment Central South University Changsha 410083 China Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals Changsha 410083 China

A hydrometallurgical process for tungsten extraction and recovery from scheelite is *** technology includes leaching scheelite using phosphoric acid as chelating agent in nitric acid solutions,extracting tungsten by solvent extraction and reusing leaching *** the leaching process,affecting factors,such as temperature,leaching time,nitric acid and dosage of phosphoric acid,were examined on recovery of *** show that more than 97%of tungsten could be extracted under conditions of leaching temperature of 80-90°C,HNO3 concentration of 3.0-4.0 mol/L,liquild-to-soild ratio of 10:1,H3PO4 dosage of 3 stoichiometric ratio and leaching time of 3 *** extraction was then employed for the W recovery from the leachate with a organic system of 40%(v/v)N235,30%(v/v)TBP,and 30%sulfonated *** 99.93%of W was extracted and ammonium tungstate solution containing 193 g/L W was obtained with a stripping rate of 98.10%under the optimized conditions.

关键词： scheelite nitric acid phosphoric acid coordination leaching

On the low cycle fatigue behaviour of an Al-Zn-Mg-Cu alloy processed via non-isothermal ageing

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Journal of Materials Science & Technology 2024年第1期168卷 227-238页

作者： Guangyi Guo Guofu Xu Yuan Tang Zhihao Zhao Zhihao Yi Haoran Li Ruohan Wang Xiaoyan Peng School of Materials Science and Engineering Central South UniversityChangsha 410083China Key Laboratory of Nonferrous Materials Science and Engineering of Ministry of Education Changsha 410083China

The low cycle fatigue behaviour of an Al-Zn-Mg-Cu alloy processed via non-isothermal ageing(NIA)was examined at different strain *** showed that NIA improved the low cycle fatigue life(more than 7000 cycles)by optimising the precipitate configuration within 5.5 h while maintaining comparable mechanical properties(570 MPa for tensile strength)and conductivity(nearly 39%IACS)to conventional isothermal ageing,*** observation combined with molecular dynamic simula-tion revealed that precipitation configuration manipulated by NIA had a crucial effect on fatigue resis-tance.A great number of repeatedly sheared and locally destructed GP zones enhanced co-planar slip and slip localisation in the under-aged alloy during the early stage of NIA,responsible for the dramatic displacement steps on the surface and resultant poor fatigue *** the NIA further proceeded,moderately coarsened precipitates with an average dimension of 6.0 nm and elevated number density ef-fectively impeded the dislocation movement and weaken the slip localisation to a great extent,improving the fatigue performance within a few hours.

关键词： Non-isothermal ageing Fatigue Al-Zn-Mg-Cu alloy Precipitate manipulation Slip localization

Preheating-assisted solid-state friction stir repair of Al-Mg-Si alloy plate at different rotational speeds

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 725-736页

作者： Hui Wang Yidi Li Ming Zhang Wei Gong Ruilin Lai Yunping Li State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Research Institute of Light Alloy Central South UniversityChangsha 410083China

Additive friction stir deposition(AFSD)is a novel structural repair and manufacturing technology has become a research hotspot at home and abroad in the past five *** this work,the microstructural evolution and mechanical performance of the Al-Mg-Si alloy plate repaired by the preheating-assisted AFSD process were *** evaluate the tool rotation speed and substrate preheating for repair quality,the AFSD technique was used to additively repair 5 mm depth blind holes on 6061 aluminum alloy *** results showed that preheat-assisted AFSD repair significantly improved joint bonding and joint strength compared to the control non-preheat substrate ***,increasing rotation speed was also beneficial to improve the metallurgical bonding of the interface and avoid volume *** preheating conditions,the UTS and elongation were positively correlated with rotation *** the process parameters of preheated substrate and tool rotation speed of 1000 r/min,defect-free specimens could be obtained accompanied by tensile fracture occurring in the substrate rather than the repaired *** UTS and elongation reached the maximum values of 164.2MPa and 13.4%,which are equivalent to 99.4%and 140%of the heated substrate,respectively.

关键词： additive friction stir deposition structural repair tool rotation speed Al alloy

Pegmatite remote sensing extraction and metallogenic prediction in Azubai area,Xinjiang

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中国有色金属学会会刊：英文版 2011年第S3期21卷 543-548页

作者： PENG Guang-xiong1, 2, YE Zhen-chao1, 2, GAO Guang-ming1, 2, FENG De-shan1, XIONG Yun1 1. School of Geosciences and Info-Physics, Central South University, changsha 410083, China 2. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education, changsha 410083, China School of Geosciences and Info-Physics Central South University Changsha 410083 China Key Laboratory of Metallogenic Prediction of Nonferrous Metals Ministry of Education Changsha 410083 China

Remote sensing technique plays an important role in geological prospecting in Altay because of the remote location and steep terrain with mountains. Pegmatite has important implications for metallogenic prospecting as most of rare metals occurs in it. Pegmatite information from optical and radar images was extracted, and the spatial distribution and scale of pegmatite were generalized in Azubai, Altay. Three mining targets, that is, Halon-Azubai, Kuermutu-Tuyibaguo and Zhuolute-Akuoyige, were delineated based on the analysis of pegmatite information, structure interpretation and other geological data.

关键词： pegmatite remote sensing information extraction metallogenic prediction

Removal of impurities from scandium chloride solution using 732-type resin

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Journal of Rare Earths 2018年第3期36卷 311-316页

作者： Guotao Zhou Qinggang Li Pan Sun Wenjuan Guan Guiqing Zhang Zuoying Cao Li Zeng School of Metallurgy and Environment Central South UniversityChangsha 410083China Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals Changsha 410083China

The deep removal of Al, Fe（Ⅱ/Ⅲ）, Ca, Zr, Ti and Si from scandium chloride solution was carried out by using 732-type strong acid cation exchange resin. The effects of pH value, contact time and complexing agents（EDTA） on the purification process are investigated. The results indicate that the 732-type resin have a good scandium selectivity and the adsorption order is Sc 〉 Fe（Ⅲ）〉Al 〉 Ca 〉 Zr 〉 Ti 〉 Si in the pH range of 1-3. The separation of Sc and Zr, Si, Ti can be directly carried out because the resin have a good adsorption effect on Sc, AI and Fe（Ⅲ） but poor adsorption effect on Zr, Si and Ti under the condition of pH = 2.5 and contact time 180 min. The Fe（Ⅱ）, Ca and Al are selectively adsorbed on the resin by adding reducing agent ascorbic acid and EDTA into the solution for reducing Fe（Ⅲ） to Fe（Ⅱ） and complexing *** using two-step ion exchange adsorption separation method, the removal rates of Fe（Ⅲ）, Ti, Al, Ca, Zr and Si are 95.5%,99.8%,100%,98.2%,98.6% and 100%,respectively.

关键词： Scandium Ion exchange Removal Impurity Reduction Rare earths

Mechanical property and cellular structure of an additive manufactured FeCoNiCrMo_(0.2) high-entropy alloy at high-velocity deformation

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Journal of Materials Science & Technology 2023年第8期139卷 156-166页

作者： Wenshu Li YiYu Huang ZhongHao Xie Haoyu Chen Weihua Li Bin Liu Bingfeng Wang State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China School of Materials Science and Engineering Central South UniversityChangsha 410083China

The microstructural modification for cellular structures can achieve the improvement of dynamic me-chanical properties of a selective laser melted FeCoNiCrMo_(0.2)high-entropy alloy(SLM-FeCoNiCrMo_(0.2)HEA)and can expand its promising applications in the field of high-velocity *** this work,FeCoNiCrMo_(0.2)HEAs with cellular structures in different sizes were produced by selective laser melt-ing(SLM)with different process *** dynamic mechanical properties and microstructure of the SLM-FeCoNiCrMo_(0.2)HEA were *** dynamic mechanical properties of the SLM-FeCoNiCrMo_(0.2)HEA increased with decrease of average size of cellular structures,and the values of them were sensitive to strain *** energy absorption,compressive strength and yield strength of the SLM-FeCoNiCrMo_(0.2)HEAs reached 315.6 MJ/m^(3),2.2 GPa and 775.6 MPa,respectively at a strain rate of 2,420 s^(−1),under the process parameters of laser power and scanning speed of 330 W and 800 mm/s,respectively,where the corresponding average size of cellular structures in the HEAs was 483.6 *** value of strain-hardening rate of the SLM-FeCoNiCrMo_(0.2)HEA was about 5.1 GPa at a strain level of 0.1,which was much higher than that of the powder-metallurgy FeCoNiCrMo_(0.2)*** cellular structure was formed inside the molten pool with segregation of Mo on the *** localization appeared in the cellular structures,forming several deformation bands after high strain-rate *** elemental segre-gation strengthening and dislocation strengthening are considered to be the main strengthening mecha-nisms in SLM-FeCoNiCrMo_(0.2)HEA.

关键词： FeNiCr-based HEA Additive manufacturing Mechanical property Cellular structure Strengthening mechanisms