Deformation behavior characterized by reticular shear bands and long chain twins in Mg-Gd-Nd(-Zn)-Zr alloys

Abstract

We analyzed the deformation behavior of Mg-Gd-Nd(-Zn)-Zr alloys under high temperature uniaxial compression, and reported two special nucleation mechanisms of dynamic recrystallization (DRX): Nucleation and expansion of DRX based on reticular shear bands (Shear band dynamic recrystallization, SBDRX) and long chain twins (Twin dynamic recrystallization, TDRX). The reticular shear bands in Mg-Gd-Nd-Zr alloy are mainly caused by the crossing of strain gradients from different directions, which is related to the high activity of pyramidal slip at high temperature. The addition of Zn makes the DRX mechanism mutate, and TDRX is dominant in Mg-Gd-Nd-Zn-Zr alloy. The nucleation of a large number of {10–12} twins is abnormal, which may be related to the decrease of I2 stacking fault energy caused by Gd/Nd–Zn compound addition. Based on the mechanical properties and microstructure, it can be concluded that the addition of Zn can promote the DRX, reduce the deformation resistance and improve the workability.

Keywords

• Mg-Gd-Nd(-Zn)-Zr
• Hot deformation
• Reticular shear bands
• {10–12} twins
• Dynamic recrystallization