Microstructure and Texture Through Thixomolding and Thermomechanical Processing and the Role of Mg17Al12 Particles

Thixomolding and thermomechanical processing (TTMP) is a pathway through which it is possible to produce Mg alloy sheet with both a fine grain size and a weak basal texture. Following static recrystallization, the texture of TTMP AZ61 is comparable to that of rare-earth Mg alloy sheets. The beta-Mg17Al12 particles in the alloy serve several important roles. Pinning during rolling retards dynamic recrystallization, thereby preventing the development of the typical Mg sheet deformation texture. Recrystallized grains form near clusters of beta-particles and in the grain mantle regions. Larger beta-particles pin boundaries during subsolvus thermal exposures and therefore provide grain size stability during annealing. The size and spatial arrangement of the beta-particles are relatively stable during processing, so modifications to optimize the texture reduction or grain size stability would require changes in composition or modifications in the Thixomolding parameters.