The microstructure evolution and deformation mechanism in a casting AM80 magnesium alloy under ultra-high strain rate loading

作     者：Pengcheng Guo Xiao Liu Biwu Zhu Wenhui Liu Liqiang Zhang 

作者机构：School of Mechanical and Electrical EngineeringCentral South University of Forestry and TechnologyChangsha 410004China School of Material Science and EngineeringHunan University of Science and TechnologyXiangtanHunan 411201China 

出 版 物：《Journal of Magnesium and Alloys》 (镁合金学报（英文）)

年 卷 期：2022年第10卷第11期

页      面：3205-3216页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：supported by the National Natural Science Foundation of China (Nos. 51975201 and 52071139) the Natural Science Foundation of Hunan Province (No.2019JJ50586) 

主　　题：AM80 mg alloy Deformation mechanism Ultra-high strain rate Twinning Dynamic recrystallization 

摘      要：Ultra-high strain rate impact tests were conducted by Split-Hopkinson pressure bar to investigate the microstructure evolution and impact deformation mechanism of a solution treated casting AM80 Mg alloy at 25, 150 and 250 ℃ with a strain rate of 5000 s^(-1). The microcrack and dynamic recrystallization(DRX) preferentially nucleate at grain boundary(GB) and twin boundary(TB), especially at the intersections between GBs and TBs, and then propagate along twin direction. In contrast, the adiabatic shear bands preferentially occur at high-density twined regions. At 25 ℃, the dominated deformation mechanisms are basal slip and twinning. As deformation temperature increases to 150and 250℃, the deformation gradually shifts to be dominated by a coordinated mechanism among non-basal slip, twinning and DRX. The flow stress behavior and deformation mechanism indicate that the degree of decrease in flow stress with temperature is associated with the change of deformation mode.