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 β-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 β-particles and in the grain mantle regions. Larger β-particles pin boundaries during subsolvus thermal exposures and therefore provide grain size stability during annealing. The size and spatial arrangement of the β-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.