Initial Stage of Plasticity of Mg-Y-Zn Alloys Containing LPSO Phase

Abstract

Extruded magnesium alloys containing Long-Period Stacking Ordered (LPSO) phases combine low density with high mechanical strength at room temperature and good creep resistance at intermediate temperatures [1-2]. The alloy extruded at low temperature exhibits a microstructure consisting of a mixture of fine equiaxed and randomly oriented recrystallised α-Mg grains (DRXed grains), coarse elongated non-DRXed α-Mg grains highly oriented with the basal plane parallel to the extrusion direction, and fibre-shaped LPSO-phase elongated along the extrusion direction also oriented with the basal plane parallel the extrusion direction [3-4]. Independently of the loading mode (tension or compression), the beginning of plasticity is always controlled by the activation of the basal slip system in the DRXed grains. The non-DRXed grains behave elastically under tension and deform by the activation of tensile twinning under compression along the extrusion direction [5].