沿晶界疲劳开裂机理(英文)

Intergranular Fatigue Cracking Mechanisms

采用扫描电镜电子通道衬度 (SEM ECC)技术 ,系统地研究了铜晶体中各种不同晶界的疲劳开裂行为 .直接的观察证据表明 :各种随机大角度晶界的疲劳开裂归因于驻留滑移带对晶界的撞击作用及随后的位错塞积 ;而当驻留滑移带能够连续穿过小角度晶界时 ,则不产生位错塞积和萌生沿晶界疲劳裂纹 .沿晶界疲劳开裂与否与驻留滑移带和晶界的交互作用方式密切相关 ,而与晶界结构本身无关 .

Intergranular fatigue 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 various random large-angle GBs due to impingement of persistent slip bands (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.