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在透射电镜中对 Fe-3%Si 单晶体薄膜进行拉伸试验,观察了在受力状态下裂纹尖端的位错行为及固溶氢的影响。结果表明,在受力时裂尖会自动发射位错。位错一旦从裂尖发射,便很快离开裂纹尖端以反塞积群形式存在于塑性区中。在裂纹尖端与塑性区之间存在一无位错区(DFZ)。裂纹扩展包括裂尖发射位错的塑性过程以及 DFZ 解理的脆性过程。固溶的氢改变了裂纹尖端的位错分布,促进了位错从裂尖发射,致使 DFZ 的长度减小甚至消失。
The tensile test of Fe-3% Si single crystal thin film was carried out in transmission electron microscope, and the dislocation behavior at crack tip and the effect of solution hydrogen on the crack tip were observed. The results show that the crack tip will automatically emit dislocations when subjected to force. Once dislocated from the crack tip, it quickly leaves the crack tip and exists in the plastic zone in the form of anti-plugging buildup. There is a dislocation-free zone (DFZ) between the crack tip and the plastic zone. Crack propagation includes the plastic process of crack tip emission dislocation and the brittle process of DFZ cleavage. The dissolved hydrogen changes the dislocation distribution at the crack tip and promotes dislocation emission from the crack tip, resulting in the decrease or even disappearance of the DFZ length.