Dynamic recrystallization behaviors of Mg-Gd-Y-Zn-Zr alloy with different morphologies and distributions of LPSO phases

Abstract

The dynamic recrystallization (DRX) behaviors of a Mg-Gd-Y-Zn-Zr alloy were studied in this paper. The samples were divided into two groups (#1 and #2) and had different morphologies and distributions of long-period stacking order (LPSO) phases. The sample #1 had both laminar and block-shaped LPSO phases while the sample #2 only had block-shaped LPSO phases. The initial grain size was about 200µm in both the samples #1 and #2. During hot compression at 763K, the laminar LPSO phases in the sample #1 could motivate kink bands and delayed the DRX, so that the volume fraction of DRX grains was only 15% at a logarithmic strain of ε = 1.5; by contrast, both the twins and block-shaped LPSO phases in the sample #2 could assist the DRX, which led to a high volume fraction of DRX grains (70%) at a logarithmic strain of ε = 1.5. Room temperature tensile tests after hot compression indicated that the sample #1 had high yield strength while the sample #2 had high ductility. It was considered that their different mechanical properties were attributed to both the basal texture intensity and the volume fraction of DRX grains.