溶解促进位错发射,运动导致黄铜薄膜应力腐蚀的TEM原位观察

用特殊设计的恒位移加载台可以在ＴＥＭ中原位观察黄铜在纯水中局部溶解前后裂尖位错形核的变化，从而可以确定局部阳极溶解对位错发射，增殖和运动的影响，也可原位观察纳米级应力腐蚀裂纹的形核和扩展，结果表明，如用薄膜试样，黄铜在室温高纯水中能发生ＳＣＣ，在裂纹形核前，通过阳极溶解的促进作用，在低应力下就能导致位错的发射、增殖和运动，当溶解引起的位错发射，运动达到临界状态时，纳米级微裂纹就将在无位错区中不连续

IN SITU TEM OBSERVATION OF DISLOCATION EMISSION, MOTION INDUCED BY ANODIC DISSOLUTION AND THE INITIATION OF SCC IN BRASS THIN FOIL

The in situ TEM observations of dislocation emission, motion and the initiation of nanocrack in brass in corrosive solution were carried out. Using a special constant displacement device, the dislocation configuration change ahead of a loaded crack tip before and after anodic dissolution in the deionized water and the initiation, propagation of nanometre scale stress corrosion cracks has been observed. The results showed that SCC in brass thin foil specimen could occur in water. The localized anodic dissolution of brass in water at room temperature facilitated dislocation emission, multiplication and motion. A nanocrack initiated in the DFZ or at the blunted crack tip in corrosion solution after dislocations emission, multiplication and motion reached a critical condition. Because of the influence of the corrosion solution, the nanocrack will propagate and form a cleavage or intergranular microcrack during stress corrosion instead of blunting in to a void as it does during a tension test without solution.