摘要
研究了晶粒尺寸为 85 μm的大晶粒AZ91镁合金在高温下的超塑拉伸变形行为。结果表明 ,大晶粒AZ91合金能在高温下获得超塑性。在 35 0℃下 ,应变速率为 3× 10 - 4s- 1 拉伸时 ,最大伸长率达2 2 8%。 30 0℃下 4 0 %的预应变可以改善合金在更高温度下的超塑性能。在超塑拉伸变形初期 ,动态再结晶细化了合金的晶粒 ,呈现出细晶超塑的特征 ;随着应变量的增加 ,合金的晶粒长大趋势不明显。大晶粒AZ91合金的超塑性变形机制是晶界滑移控制下的孔洞连接协调机制。
The superplastic behavior of wrought AZ91 alloy with coarse grains was investigated. The results show that an elongation of 228.5% is obtained in AZ91 alloy in spite of the coarse grains with the grain size of 85 μm. Two-step method enhances the superplastic property of AZ91 alloy. The microstructure is keeping the same scale of grains after superplastic testing. The microstructure observation shows that the grains become fine due to dynamic recrystallization during the initial deformation stage, for which the microstructure condition for superplastic deformation in AZ91 alloy with coarse grains can be provided. With the deformation being extended, the trend which the grains become coarse is not clearly observed. The fracture surface indicates that the mechanism of superplastic deformation in AZ91 alloy is controlled by the grain boundary sliding accompanied with cavities interlinking.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2004年第3期25-29,共5页
Transactions of Materials and Heat Treatment
基金
中国博士后科学基金资助项目 (No.2 0 0 30 330 90 )
关键词
AZ91合金
大晶粒
超塑行为
机制
Deformation
Dynamics
Grain size and shape
Microstructure
Recrystallization (metallurgy)
Superplasticity
