Study on the room temperature compression deformation mechanism and microstructural evolution of Mg-Gd-Y-Zr alloy

Abstract

This study explores the dynamic impact deformation mechanisms of Mg-Gd-Y-Zr alloys, specifically focusing on the influence of varying Gd content. Using metallographic observation, SEM, EDS, XRD, EBSD, and TEM, along with hardness and room-temperature compression tests, the research investigates the effects of Gd content on the microstructure, mechanical properties, and deformation behaviors of as-cast Mg-(x)Gd-3Y-0.5Zr (x = 6.5/7.5/8.5) alloys.The results show that increasing Gd content reduces grain size and increases the volume fraction of the non-equilibrium eutectic phase Mg24(Gd,Y)5, though with smaller phase dimensions. These alloys exhibit excellent compressive properties at room temperature, with the highest compression deformation rate of 27.8 % observed at 6.5 % Gd and the maximum compressive strength of 401 MPa recorded at 8.5 % Gd, surpassing some high-Gd-content cast and extruded alloys.At lower Gd content, basal slip and tensile twinning are the primary deformation mechanisms. As Gd content increases, these mechanisms evolve to include prismatic slip and compressive twinning. The fracture mode transitions from predominantly ductile to a combination of ductile and brittle features, with an increase in brittle cleavage at higher Gd levels.