小角度晶界铜晶体的循环形变及饱和位错组态ECC观察

Cyclic Deformation Behavior and Observation of Saturation Dislocation Patterns of Copper Crystals Containing Low angle Grain Boundaries by SEM ECC Technique

通过对具有小角度晶界的铜晶体进行循环变形，发现其循环饱和切应力在塑性切应变范围０．６—４．７×１０－３内基本不变（约为３０ＭＰａ）。采用电子通道衬度（ＥＣＣ）技术观察了其循环饱和时晶内、晶界及形变带附近的位错组态，发现在低应变幅下（γｐ１＝０．６×１０－３）晶内为驻留滑移带及脉络两相结构。随应变幅升高（γｐ１＞１．７×１０－３）驻留滑移带逐渐增多，最后形成规则的位错墙结构，并且位错墙连续穿过小角度晶界，在局部区域还发现小角度晶界两侧出现无位错区（ＤＦＺ）；

? Cyclic deformation tests were carried out on copper crystal containg low angle grain boundaries under constant plastic shear strain amplitude control. It was found that the saturation resolved shear stress nearly maintains constant (￣30MPa) at the plastic resolved shear strain ranging from 0.6 to 4.7×10 -3 . Dislocation patterns within grains and in the vicinity of low angle grain boundaries were observed using electron channelling contrast (ECC) technique by SEM. The results show that the dislocation patterns consists of persistent slip bands (PSBs) and vein structures at the low plastic strain amplitude (γ p1 =0 6×10 -3 ). With increasing plastic strain amplitude, large volume fraction of persistent slip bands and regular dislocation walls were observed. Dislocation walls and persistent slip bands could cross through the low angle grain boundary continuously except that the dislocation free zones (DFZs) appeared at some local regions. Combining the observations of deformation bands, it was found that the dislocation walls are basically parallel to the deformation bands. 