Spherical strengthening precipitate in a Mg-10 wt%Y alloy with superhigh pressure aging

摘要

A Mg-10 wt% Y alloy exhibited age hardening response by both artificial aging at 220 C (T6) and superhigh pressure aging (6 GPa) at 300 C (SHP-300). A spherical strengthening precipitate (Mg_(24)Y_5) was achieved after SHP-300 heat treatment, which was different from conventional plate-shaped strengthening precipitate (P') after T6 treatment. Compared with the T6 state sample, the peak hardness, strength and ductility were improved by means of SHP-300 treatment. The improved hardness and strength were associated with the nano-scale precipitate (Mg_(24)Y_5) and strain hardening. The large elongation was ascribed to the formation of spherical precipitate, which can effectively reduce the stress concentration during the deformation process.