纳米孪晶Cu中局部剪切应变诱导的退孪生行为  

DETWINNING BEHAVIOR INDUCED BY LOCAL SHEAR STRAIN IN NANOTWINNED Cu

作　　者：白敬胜 卢秋虹[1] 卢磊[1] 

机构地区：[1]中国科学院金属研究所沈阳材料科学国家(联合)实验室,沈阳110016

出　　处：《金属学报》2016年第4期491-496,共6页Acta Metallurgica Sinica

基　　金：国家重点基础研究发展计划项目2012CB932202;国家自然科学基金项目51420105001;51371171和51471172资助~~

摘　　要：对择优取向纳米孪晶结构Cu样品进行室温轧制变形.微观结构研究发现,当变形压下量为15%时,样品中出现了与轧制方向呈30o^45°方向(最大剪切应力方向)分布的退孪生带.退孪生带中孪晶片层明显粗化,孪晶界上出现大量Shockley位错.塑性变形过程中较小应变时,纳米孪晶Cu中局部退孪生机制是协调局部剪切应变的主要机制.Nanotwinned materials have attracted widespread attention due to their superior mechanical properties, such as high strength, good ductility and work hardening. Experimental and molecular dynamics（MD） simulation results had indicated that there are three distinctly different dislocation- mediated deformation mechanisms in nanotwinned metals, namely dislocation pile-up against and slip transfer across twin boundaries（TBs）, Shockley partials gliding on twin boundaries leading to twin boundary migration, and threading dislocations slip confined by neighboring twin boundaries. However, most of the previous studies are focused on the homogenous plastic deformation under tension and compression tests, the non- homogenous deformation and its deformation mechanism, especially under low strain and complex stress condition/confined condition, of nanotwinned metals are still not explored so far. In this study, the electrodeposited bulk Cu samples with preferentially oriented nanotwins were cold rolled with the normal of the rolling plane parallel to the growth direction（ND//GD） to strain of 15% at room temperature.The microstructure features of as-rolled Cu were investigated by SEM and TEM. Microstructure evolution indicates that many detwinning bands appeared in the direction about 30° ~45° with respect to the rolling direction, which is the direction with the largest shearing stress. The twin lamellae in the detwinning bands coarsened obviously. Based on calculation of the local shear strain and strain gradient of TBs in a selected detwinning band, it indicates that the maximum shear strain occurs in the middle of the deformation bands, and its detwinning mechanism is directly related the localized shear strains（γ）. The twin lamellae in the detwinning bands were coarsened obviously. When 0.3g0.8, the detwinning process via producing amount of Shockley dislocations on twin boundaries dominates the deformation. After detwinning, Shockley partial dislocations stored at the area with the maximum strain grad

关 键 词：CU 纳米孪晶 轧制形变 退孪生 剪切应变 

分 类 号：TG146[一般工业技术—材料科学与工程]