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通过附设的拉伸台装置,在透射电子显微镜(TEM)下,可观察静载下裂纹萌生和扩展的过程,但目前还不能直接对周期载荷下的裂纹过程进行分析研究。为了实现在TEM下对疲劳裂纹近旁的组织结构进行原位分析,采用在断口上镀镍的方法,制取含有疲劳断口的金属薄膜试样。由于这种薄膜试样的制作是在镀层和金属基体这一结合体上进行的,因而欲在试样的切割、研磨、冲剪及电解抛光等诸多环节中,避免镀层和基体的分离,获取完美的薄膜试样,在具体的操作上须克服许多技术上的难点。现将试样制备过程中的要点简介如下:
Through the attached tension stage device, under the transmission electron microscope (TEM), the initiation and propagation of crack under static load can be observed, but the crack process under cyclic loading can not be analyzed directly. In order to realize the in-situ analysis of the tissue structure near the fatigue crack under the TEM, a metal thin film sample containing fatigue fracture was prepared by the method of nickel plating on the fracture surface. Since the production of the thin film sample is carried out on the combination of the plating layer and the metal substrate, the separation and the acquisition of the plating layer and the substrate are avoided in many steps of the sample cutting, grinding, punching and electropolishing Perfect film samples, in the specific operation to overcome many technical difficulties. Now the sample preparation process outlined as follows: