本文采用EBSD技术研究了室温下AZ31镁合金单轴压缩实验中不均匀变形对孪生行为的影响. 死区、易变形区、自由变形区处孪生分数统计结果表明, 当应变小于8%时, 3处孪生分数不相等, 应变增加到8\%时, 3处孪生分数均达到90\%左右, 孪生基本完全, 不均匀变形在低应变下对3处孪生分数影响很大, 而在高应变下影响很小. 对2\%应变下3处孪生变体选择机制进行分析, 发现80%以上开动的孪生变体都是对应第一大和第二大Schmid因子变体, 表明3处孪生变体激活均满足Schmid定律. 由于应力状态不同, 自由变形区同时开动两个变体的晶粒百分数大于死区和易变形区.
The effect of inhomogeneous deformation on twinning behavior during uniaxial compression of AZ31 magnesium alloy at room temperature was investigated with electron backscattered diffraction (EBSD technique. The evolution of twin area fraction in three locations, typical of a dead zone, an easy zone and a free zone with strain was analyzed. The results show that the twin area fractions at the locations in dead zone, easy zone and free zone are different at compression strains less than 8\%. As compression strain reaches 8%, the area fraction of extension twins at these three locations is almost the same, and is about 90\%. Inhomogeneous deformation exerts much effect on the twin area fraction at the locations in the three zones at low strains while exerts little effect at high strains. Twin variant selection in the three zones at 2% strain was also analyzed. The results show that the twin variant activation is governed by the Schmid factor criterion in all the three zones. However, the percentage of grains with two twin variant types in free zone is higher than that in dead zone and easy zone, due to the different stress states in this location.
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