关键词: 晶界, 疲劳裂纹, 驻留滑移带, 位错塞积

Abstract:

Intergranular fat igue cracking mechanisms of copper crystals containing various grain boundaries(GBs) were investigated by electron channeling contrast(ECC) technique in scanning electron microscope(SEM). Evidence by direct observations indicates that fatigue cracking always nucleated along var-ious random large-angle GBs due to impingement of persistent slipbands (PSBs) and pile-up of dislocations.However, low-angle GBs do not produce fatigue cracks because the dislocations can be transferred through the GBs by PSBs. It is suggested that intergranular fatigue cracking strongly depends on the interaction mode of PSBs with GBs, while the GB structure itself plays a much less role.

Key words: grain boundary, fatigue crack, persistent slip bands, pile-up of dislocations