Influence of processing temperature on microstructure and microhardness of copper subjected to high-pressure torsion  

作　　者：XIE ZiLing1,2,XIE JiJia2,HONG YouShi2 & WU XiaoLei2 1 College of Architecture and Civil Engineering,University of Wenzhou,Wenzhou 325035,China 2 State Key Laboratory of Nonlinear Mechanics,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China 

出　　处：《Science China(Technological Sciences)》2010年第6期1534-1539,共6页中国科学（技术科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos.10721202,10772178,50571110)

摘　　要：Cu samples were subjected to high-pressure torsion (HPT) with up to 6 turns at room temperature (RT) and liquid nitrogen temperature (LNT),respectively.The effects of temperature on grain refinement and microhardness variation were investigated.For the samples after HPT processing at RT,the grain size reduced from 43 μm to 265 nm,and the Vickers microhardness increased from HV52 to HV140.However,for the samples after HPT processing at LNT,the value of microhardness reached its maximum of HV150 near the center of the sample and it decreased to HV80 at the periphery region.Microstructure observations revealed that HPT straining at LNT induced lamellar structures with thickness less than 100 nm appearing near the central region of the sample,but further deformation induced an inhomogeneous distribution of grain sizes,with submicrometer-sized grains embedded inside micrometer-sized grains.The submicrometer-sized grains with high dislocation density indicated their nonequilibrium nature.On the contrary,the micrometer-sized grains were nearly free of dislocation,without obvious deformation trace remaining in them.These images demonstrated that the appearance of micrometer-sized grains is the result of abnormal grain growth of the deformed fine grains.Cu samples were subjected to high-pressure torsion (HPT) with up to 6 turns at room temperature (RT) and liquid nitrogen temperature (LNT),respectively.The effects of temperature on grain refinement and microhardness variation were investigated.For the samples after HPT processing at RT,the grain size reduced from 43 μm to 265 nm,and the Vickers microhardness increased from HV52 to HV140.However,for the samples after HPT processing at LNT,the value of microhardness reached its maximum of HV150 near the center of the sample and it decreased to HV80 at the periphery region.Microstructure observations revealed that HPT straining at LNT induced lamellar structures with thickness less than 100 nm appearing near the central region of the sample,but further deformation induced an inhomogeneous distribution of grain sizes,with submicrometer-sized grains embedded inside micrometer-sized grains.The submicrometer-sized grains with high dislocation density indicated their nonequilibrium nature.On the contrary,the micrometer-sized grains were nearly free of dislocation,without obvious deformation trace remaining in them.These images demonstrated that the appearance of micrometer-sized grains is the result of abnormal grain growth of the deformed fine grains.

关 键 词：COPPER high pressure TORSION (HPT) MICROSTRUCTURE GRAIN size MICROHARDNESS CRYOGENIC temperature 

分 类 号：TG146.11[一般工业技术—材料科学与工程]