Investigating the deformation behavior and microstructure evolution of Mg-3Zn-1Sn alloy with low activation energy of deformation during isothermal compression

Abstract

Hot compression (HC) experiments were carried out on the homogenized Mg-3Zn-1Sn (ZT31, wt.%) alloy at various deformation parameters. The results indicated that both the increase in deformation temperature (T) and the decrease in strain rate ($\dot{\epsilon }$$\dot{\epsilon }$) are responsible for the significant reduction in flow stress ($\sigma$$\sigma$). The calculated average activation energy of deformation during the considered conditions is 124 kJ/mol, which is lower than many reported Mg alloys. Meanwhile, the ZT31 alloy has an instability criterion consistently greater than 0. Therefore, it exhibits outstanding hot deformation capability. The processing map shows that ZT31 alloy is safer to process above 300 °C, while the $\dot{\epsilon }$$\dot{\epsilon }$ has a limited influence on the processability of ZT31 alloy. During the middle and late stages of deformation, the predominant deformation mechanisms of ZT31 alloy are basal slip and pyramidal <c+a> slip. The simultaneous activation of basal slip and pyramidal <c+a> slip puts the rotation of the c-axis in a dynamic balance, which ultimately manifests as the c-axis being approximately parallel to the compression direction (CD). The DRX mechanism of ZT31 alloy includes continuous DRX and discontinuous DRX.