A Study of Microstructure Evolution for Mg Alloy Subjecting to Multi-Pass Equal Channel Angular Extrusion

Equal channel angular extrusion (ECAE) has been recognized as one of the effective ways for grain refinement. The microstructures after ECAE have been studied for many alloys with relating to mechanical properties. However, the evolution of microstructures and their relationship with the prior conditions are rarely studied. In the present work, the microstructures and tensile behavior of a Mg alloy, AZ31, were investigated after each pass of ECAE. The results revealed an unreported rule that the alloy follows for texture evolution, where the basal texture or namely the focused c-axis orients 45° for each ECAE process, regardless of the prior microstructure. This implies that the texture or grain orientation development under ECAE could be irrelevant with shearing, but have relation to rotation. The tensile behavior of the extruded samples with different passes has been found to fit very well with the microstructure, i.e., the varying yield strengths are highly related with the texture.