Synergistic effect of LPSO and eutectic phase on mechanical properties of Mg-Gd-Nd-Zn-Zr alloy during equal channel angular pressing

Abstract

In this paper, the homogenized Mg-9Gd-2Nd-1.6Zn-1Zr (wt%) alloys were subjected to various equal channel angular pressing (ECAP) passes (1, 2, 4 and 8) with Bc route at 400 °C. Then, the microstructure evolution and strengthening mechanisms of alloys were systematically investigated. The results show that the coarse deformed grains are completely consumed by the dynamic recrystallized (DRX) grains, the number of dynamic precipitates gradually increases, and the intensity of basal texture of the alloy is gradually weakened with increasing ECAP passes. After 8 passes ECAP, the grain size is dramatically refined from 50 μm (homogenized) to 2.1 μm (8p-ECAPed), which is mainly due to the DRX, particle-stimulated nucleation (PSN) induced by broken eutectic phase and hinder grain growth of dynamic precipitates. The excellent comprehensive mechanical properties are achieved by 4 passes, and the corresponding yield strength (YS) and ultimate tensile strength (UTS) as well as elongation (EL) are 321 MPa, 378 MPa and 14.4％, respectively. This can be mainly ascribed to the combined effect of broken eutectic phase, DRX grains, kinked long period-stacking order (LPSO) and dynamic precipitates.

Keywords

• Mg-Gd-Nd-Zn-Zr
• ECAP
• Microstructure
• Mechanical properties