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为了研究由剧烈塑性滚柱滚压在纯铜表层诱导出的梯度纳米/微米结构特征及其晶粒细化机制,采用SEM、TEM、XRD、OM等方法观察样品距表面不同深度的组织特点和材料特性。结果表明,滚压所引入的纳米/微米结构层厚度超过100μm。近表层的硬度有显著的提高,这归因于晶粒尺寸的减小,所生成的等轴纳米晶为随机晶粒取向且绝大多数晶界为小角度晶界。粗晶通过位错运动细化至几微米;变形孪生是形成亚微米晶的主要机理;纳米结构的形成由位错运动主导并伴随局部区域的晶粒旋转。
In order to study the gradient nano / micro structure induced by intense plastic roller rolling on the surface of pure copper and its grain refinement mechanism, SEM, TEM, XRD, OM and other methods were used to observe the microstructure characteristics of the samples at different depths from the surface and Material properties. The results show that the thickness of nano / micro structure layer introduced by rolling is more than 100μm. The hardness of the near-surface layer is significantly increased due to the decrease of the grain size. The resulting equiaxed nanocrystals are random grain oriented and the vast majority of grain boundaries are small-angle grain boundaries. The coarse grains are refined to a few microns by dislocation motion; the deformed twin is the main mechanism for the formation of submicron grains; the formation of nanostructures is dominated by dislocation motion and accompanied by the local grain rotation.