驻留滑移带与晶界和孪晶界的交互作用

Interactions of persistent slip bands with grain boundaries and twin boundaries

对含有退火孪晶的多晶铜进行了不同塑性应变幅下的应变疲劳实验,利用扫描电镜及其电子通道衬度技术(SEM-ECC)观察了表面滑移形貌、疲劳裂纹和位错组态,研究了驻留滑移带与晶界和孪晶界的交互作用．结果表明,在晶界附近和远离晶界处观察到位错组态分布的不均匀现象．这种不均匀性导致多晶铜中疲劳裂纹首先沿着普通大角晶界开裂,在孪晶界处由于应变相容性较好而难以产生疲劳裂纹．

Strain fatigue experiments were carried out on polycrystalline copper containing annealing twins at different plastic strain amplitudes. Surface slip morphologies, fatigue cracks and dislocation patterns were observed by scanning electron microscopy （SEM） and electron channelling contrast （ECC） technique. The interactions of persistent slip bands （PSBs） with grain boundaries （GBs） and twin boundaries （TBs） were investigated. Inhomogeneous dislocation patterns near and far away from GBs were observed. This often results in that fatigue cracks are easy to initiate along common large-angle GBs, but difficult to nucleate at the TBs because of good strain compatibility.