【摘要】 研究了轧制态AZ91镁合金在实验温度为 35 0℃～ 4 2 5℃ (0 6 7Tm～ 0 76Tm)以及应变速率为 10 - 3s- 1～ 10 0 s- 1下的超塑性变形能力及其特征。实验发现 ,轧制态AZ91镁合金在 35 0℃ (0 6 7Tm)以及应变速率为 10 - 3s- 1时获得最大延伸率 4 5 5 0 5 % ,应变速率敏感系数达到 0 6 4。通过分析表明 ,高应变速率下的超塑性变形过程中主要的变形机制为晶界滑移机制 ,但其主要的协调机制则是孔洞扩散聚集机制。更多还原

【Abstract】 The high strain rate superplastic deformation properties and characters of rolled AZ91 magnesium alloys at temperatures ranging from 623K to 698K (0.67T m～0.76T m) and at high strain rates ranging from 10 -3 s -1 to 1s -1 were investigated in this study. Rolled AZ91 magnesium alloys obtained excellent superplasticity with the maximum elongation to failure of 455.05% at 623K and strain rate of 10 -3 s -1 , and its strain rate sensitivity is high up to 0.64. The dominant deformation mechanism in high strain rate superplasticity is still grain boundary sliding (GBS). The main accommodation mechanism was microcavities coalescences, which was observed obviously in this study.更多还原