利用透射电子显微镜,对液氮温度下动态塑性形变法(LNT—DPD)制备的块体纳米孪晶铜在不同形变量下的微观结构演变进行了研究.结果表明,经LNT—DPD处理后,Cu呈现复杂的微观结构特征:由高密度的纳米尺寸形变孪晶片层团簇、纳米晶组织和含有较高密度位错结构的粗晶组织交错分布组成;其形成机制可归因于形变孪晶与剪切带共同作用的结果.揭示了经LNT—DPD处理的Cu的超高拉伸强度与其微观结构的关系.
Microstructural feature and evolution of nano-twin bulk Cu specimens produced by means of dynamic plastic deformation at liquid nitrogen temperature (LNT-DPD) have been studied using TEM. The results show that the microstructure of LNT-DPD Cu consists of high density of nano-scaled mechanical twins, nano-sized grains and coarse grains with high density of dislocations, which makes the LNT-DPD Cu exhibit a significant high tensile yield strength. Such a deformation structure was attributed to twinning and shearing during the LNT-DPD treatment.