Flow stress and microstructural evolution in as rolled AZ91 alloy during hot deformation

来源期刊：中国有色金属学报(英文版)2003年第6期

论文作者：周海涛 王渠东 尉胤红 丁文江 朱燕萍 Y. Chino M. Mabuchi

文章页码：1265 - 1269

Key words：magnesium alloy; grain refinement; recrystallization; strain softening;strain hardening

Abstract: The flow stress behavior and microstructural evolution in as rolled AZ91 alloy were studied by tensile test at temperature ranging from 573K to 698K and with initial strain rate of 10^-3-1s_-1. The results show that the activation energy of the AZ91 alloy is 96kJ/mol and the stress exponent is 3.5.Grain refinement is observed during hot deformation. It is found that grain refinement is due to dynamic recrystallization, but grain size is decreased with increasing Zener-Hollomon parameter. The deformation mechanism is dislocation cross-slip, dislocation climbs and twin intersections, which are probably suitable to the development of substructures. Twins always exist in matrix whether they are at high temperature or at low temperature. Strain induced precipitation of Mg₁₇Al₁₂ occurs in the AZ91 alloy and stabilizes the subgrain boundaries.