Fine-Grain Processing by Equal Channel Angular Extrusion of Rapidly Quenched Bulk Mg–Y–Zn Alloy

Abstract

The fine-grain processing of ingot metallurgy (IM) Mg–Y–Zn alloy, WZ73, was investigated. The alloy was initially produced by casting into a copper mold at a cooling rate of ∼50 K/s. The rapidly quenched bulk material was processed by means of equal channel angular extrusion (ECAE). The ECAE-processed material had equiaxed grains of 5.1 μm in size, and fine second-phase particles of Mg12YZn were dispersed in the grain boundaries. The Vickers hardness of the ECAE-processed material was 78. The dispersion of the second-phase particles, solid solution strengthening, and grain refinement contributed to the material’s hardness. The structure remained virtually unchanged, at least up to 673 K because the Mg12YZn phase served to pin the grain boundaries. The microstructure of IM WZ73 alloy, which is a suitable starting material for ECAE, was also considered.