Enhanced strength and ductility in Mg-9Gd-4Y–2Zn-0.5Zr alloy under high-temperature compression enabled by the LPSO phase

Abstract

Two thermomechanical treatments, namely N (510 °C/16 h) and C (510 °C/16 h + 480 °C/8 h), were employed in an extruded Mg-9Gd-4Y–2Zn-0.5Zr alloy to reveal the influence mechanism of coordinated deformation of the 14H-LPSO phase during the hot deformation process. Results revealed that the C-treated alloy(CC alloy), compared to the N-treated alloy(CN alloy), demonstrated a higher volume fraction of dynamic recrystallization (DRX) and reduced textural intensity after compression, which correlated with enhanced plasticity. In particular, the dynamic precipitation of the lamellar LPSO phase during deformation inhibited DRX nucleation and triggers the strong basal texture, in contrast to the behavior of pre-existing lamellar LPSO phases. These microstructural disparities induce the superior strength-ductility synergy of the CC alloy relative to CN alloy during high-temperature compression at 400 °C. This study highlights mechanistic insights into the interplay of DRX, texture evolution, and crack initiation phenomena associated with the 14H lamellar LPSO phase.

Keywords

• Lamellar LPSO phase
• Deformation mechanism
• Dynamic recrystallization
• Twins
• High-temperature mechanical property