对[112]双滑移取向铝单晶体进行了对称拉压疲劳试验，详细观察和对比研究了正表面和侧表面（包含两个主滑移系Burgers矢量）上的疲劳损伤与裂纹萌生过程.在正表面上两个主滑移系滑移台阶是相互平行的，呈典型的持续滑移带（PSB）损伤形貌；而在S面上则始终未见PSB,但有晶体学关系不明确的呈波纹形不均匀分布的形变花样产生，并发展导致微裂纹的萌生,其尺寸可与正表面上的PSB裂纹相匹比。由此进一步证实了循环形变累积所致的内部组织损伤是疲劳裂纹萌生的基本因素．和单滑移取向单晶体相比，在复滑移条件下的显著交滑移过程明显地促进了试样的疲劳损伤和裂纹萌生.
The [112]aluminum single crystal was tested in full push-pull at room temperature in air, with specific stress amplitudes and frequence of 15 Hz. Detailed observations were made on side-surface which contained Burgers vectors of two primary slip systems and front-surface. On front-surface typical PSBs topographies and crack initiation along PSBs have been seen. However, on side-surface where PSBs were invisible, a more complicated deformation appearance was developed, and microcracks initiated along extrusions or intrusions which were formed without a definite crystallographic relation to PSBs' The results show again that, without the aid of the surface roughness of PSBs, cracks can still be nucleated, and that the accumulative structural damage in single crystal aluminum is believed to be one of basic factors controlling crack initiation. Yet it was shown that the deformation and damage processes in single crystal aluminum are orientation dependent, and that the marked cross-slip in poly-slip crystals could accelerate the damage process which can be manifested best on side-surface.
参考文献
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