大塑性变形纳米结构Al-Mg合金中的形变缺陷和电子辐照效应

摘要

为澄清大塑性变形纳米结构Al-Mg合金中形变缺陷形成的本质,采用高分辨透射电子显微镜(HRTEM)研究电子辐照对高压扭转合金中面缺陷形成的影响.结果表明:对已有高密度面缺陷的HRTEM图像,经电子束照射一段时间后,这些面缺陷会完全消失；而在没有缺陷的HRTEM图像区域进行电子辐照,即使电子束的照射提高到足以在该区域击出孔洞,整个过程均未观察到任何晶格缺陷.因此,高压扭转合金中的面缺陷主要来源于极度的塑性变形,而与HRTEM观察过程中的电子辐照效应无关.%In order to explore the exact nature of deformation defects previously observed in nanostructured A1-Mg alloys subjected to severe plastic deformation,a more thorough examination of the radiation effect on the formation of the planar defects in the high pressure torsion (HPT) alloys was conducted using high-resolution transmission electron microscopy (HRTEM).The results show that high density defects in the HRTEM images disappear completely when these images are exposed under the electron beam for some duration of time.At the same time,lattice defects are never observed within no-defect areas even when the beam-exposure increases to the degree that holes appear in the areas.Therefore,it is confirmed that the planar defects observed in the HPT alloys mainly result from the significant plastic deformation and are not due to the radiation effect during HRTEM observation.