Effect of Multi-Pass Equal Channel Angular Pressing on the Microstructure and Mechanical Properties of a Directional Solidification Mg98.5Zn0.5Y1 Alloy

Abstract

The microstructure evolutions and mechanical properties of a directional-solidification (DS) Mg98.5Zn0.5Y1 alloy during multi-pass equal channel angular pressing (ECAP) were systematically investigated in this work. The results showed that there was a large amount of lamellar structure in the DS alloy. These lamellar structure have almost the same orientation inside the grains. After ECAP, dynamic recrystallization (DRX) occurred and the diameter of DRXed ¡-Mg grains decreased to 2μm. During ECAP, large volume fraction of LPSO phase experienced a four-step morphological evolution during ECAP, i.e. original lath1⁄4 bent lath1⁄4 cracked lath 1⁄4 smaller particles. Meanwhile, the schematic illustration of recrystallization in the DS-Mg98.5Zn0.5Y1 alloy during ECAP was established. Compression test results indicated that the alloy was markedly strengthened after multi-pass ECAP, and the main reason for the significantly enhanced mechanical properties can be ascribed to the DRXed ¡-Mg grains, kinking and refined 14H particles. [doi:10.2320/matertrans.M2019088]