超细晶铜的高温循环变形及损伤行为  

High-temperature cyclic deformation and damage behavior of ultrafine-grained copper

作　　者：李小武[1,2] 姜庆伟[1] 刘印[1] 

机构地区：[1]东北大学理学院材料物理与化学研究所,沈阳110004 [2]东北大学材料各向异性与织构教育部重点实验室,沈阳110004

出　　处：《粉末冶金材料科学与工程》2009年第1期17-20,共4页Materials Science and Engineering of Powder Metallurgy

基　　金：国家自然科学基金资助项目(50671023);教育部新世纪优秀人才支持计划资助项目(NCET-07-0162)

摘　　要：为揭示超细晶材料在高于室温条件下的动态疲劳变形行为,在室温到300℃温度范围内以及在恒应力幅为200MPa条件下研究等通道转角挤压(ECAP)法制备的超细晶铜的循环形变行为及表面变形特征。结果表明:随着温度升高,循环软化更趋明显,相应的疲劳寿命显著降低,断口形貌特征由脆性逐步转变为韧性;表面变形特征及损伤行为也与温度密切相关,例如,作为主要变形方式的大尺度剪切带在室温疲劳下大量形成;随着温度升高,晶粒长大及位错滑移增强,晶界数量和体积分数明显降低,导致剪切带变得更细且不连续,当温度高于其再结晶温度时剪切带几乎消失,晶粒内的位错滑移成为材料的主要变形方式。To reveal dynamic fatigue deformation behavior of ultrafine-grained materials at high temperature, cyclic deformation behavior and surface deformation features of ultrafine-grained copper produced by equal channel angular pressing（ECAP） were investigated at temperatures ranging from room temperature to 300 ℃ under a constant stress amplitude of 200 MPa. It is found that cyclic softening becomes much more evident and the corresponding fatigue life decreases significantly as temperature increasing, meanwhile, a gradual change in fracture surface topography from brittle to ductile occurs; in addition, the surface deformation features and damage behavior are closely related with temperature. For instances, large-scale shear bands form largely at room temperature as the main deformation mode; with temperature increasing, due to the reduction in quantity and volume fraction of grain boundaries, and the enhancement of grain growth and dislocation slip, the formed shear bands tend to become finer and discontinuous; when temperature is above that of recrystallization, dislocation slip deformation within grains governs the plastic deformation of materials.

关 键 词：超细晶铜 等通道转角挤压 循环形变 疲劳寿命 温度 剪切带 再结晶 

分 类 号：TG111.8[金属学及工艺—物理冶金]