Microstructure of Mg–In Alloy Systems and Their Room Temperature Rollability

Abstract

The Mg_0.1In_0.9 phase with FCC structure was formed in Mg–In and Mg–Al–In alloys. The LCR (Limiting Cold-Rolling ratio) at room temperature tended to increase with increasing area fraction of the Mg_0.1In_0.9 phase, and the LCR achieved 80% for the single Mg_0.1In_0.9 phase in both alloys. The hardness value of the Mg_0.1In_0.9 phase in the Mg–In binary alloys increased after rolling originated from grain-refinement by recrystallization and precipitation hardening due to processing heat generated by rolling at room temperature. On the other hand, the Mg_0.1In_0.9 phase formed in the Mg–Al–In ternary alloys was stable at room temperature and work hardened after rolling. Since the Mg_0.1In_0.9 phase dissolves about 5 mol% of Al, substituting Al for In in the Mg–In alloy was effective in reducing density. The density of the Mg₈₀Al₇In₁₃ (mol%) alloy is 2.60 Mg/m³, which is lower than that of Al, and the LCR showed 49%. In Mg–In alloys, the substitution of Al is effective in developing alloys that are easy to process at room temperature and have low density, because the Mg_0.1In_0.9 phase has a solid solution of Al and contributes to phase stabilization at room temperature.

 

This Paper was Originally Published in Japanese in J. JILM 73 (2023) 152–157.

Fig. 5 (a) TEM image of Mg₇₄In₂₆ rolled alloy (LCR: 80%). Electron diffraction patterns taken from areas A and B are shown in right side in the figure. (b) TEM image of Mg_0.1In_0.9 phase observed in region other than (a). (c) HRTEM image of Mg_0.1In_0.9 phase. (d) TEM image of grain boundary between Mg_0.1In_0.9 phases.