不同温度轧制多晶铝的微观组织与晶界分布

MICROSTRUCTURES AND BOUNDARY DISTRIBUTIONS IN Al POLYCRYSTALS ROLLED AT DIFFERENT TEMPERATURES

采用SEM-EBSD技术测试了室温和180℃条件下80%压下量轧制高纯铝样鼯的微取向分布.结果表明:平行于轧向的形变组织可分为取向分布集中和取向散布的带状组织.前者取向主要聚集于β-取向线,其中Br-取向({011}(211))的小角度(2°-5°)晶界面积率比S-({123}(634))和C-(｛112｝(111))取向的大10%-15%;随轧制温度从室温升至180℃,回复程度增强,中等角度(5°-15°)晶界面积率约升高10%.用Bishop-Hill晶体塑性理论分析β-取向线组织的塑性变形储能差异表明,取向的Taylor因子M越小,5个独立活化滑移系的组合数越多,其变形储能就越小,小角度晶界比例亦越大.

The orientation imaging micrographs （OIMs） in high purity aluminum rolled to 80% under room temperature and 180 ℃ were investigated using the SEM-EBSD technique. It was found that the elongated bands parallel to the rolling direction （RD） have two morphologies-the orientation concentrated and the orientation scattered, the orientations of the former mainly rotated toward β- fibre, and the area fraction of the low angle （2°-5°） boundaries in the bands with the Br-（{011}（211）） orientation was about 10%-15% larger than those of the S-（{123}（634）） and C-（{112}（111）） orientations. When the rolling temperature changed from the room temperature to 180 ℃, the area fraction of the middle angle （5°-15°） boundaries was increased by about 10% because of stronger recovery during rolling at 180 ℃. The energy difference of the boundary distributions for the orientations along the β-fibre has been analyzed in term of Bishop-Hill crystal plasticity theory. It is shown that the orientations with smaller values of Taylor factor M and larger combination numbers of 5 independent active systems correspond to less boundary energy and lower angle boundary during rolling.