Effect of extrusion ratio on microstructure and resulting mechanical properties of Mg alloys with LPSO phase

Abstract

The WZ21 (Mg, +, 1.8, wt% Y, +, 0.7, wt% Zn) magnesium alloy having an addition of 0.5, wt% of CaO was extruded with different extrusion ratios (4:1, 10:1, 18:1) at 350, °C. In all alloys, a long-period stacking-ordered (LPSO) phase composed of Zn and Y is formed. The microstructure was analyzed by electron backscatter diffraction (EBSD) mapping. The WZ21 alloy after extrusion with the extrusion ratio of 4:1 contains large grains. The fraction of recrystallized grains increases with increasing extrusion ratio. All samples have basal planes oriented parallel to the extrusion direction (ED) and this texture weaken with increasing extrusion ratio. Mechanical properties of the samples were investigated during compression along ED at room temperature and at a constant strain rate of 10−3, s−1. Concurrently, with the deformation tests, the acoustic emission (AE) response of the specimens was recorded. The maximum of the AE count rate in all cases corresponds to the macroscopic yield point.