Dynamic strain aging precipitation of Mg17Al12 in AZ80 magnesium alloy during multi-directional forging process

Abstract

Dynamic aging precipitation of Mg₁₇Al₁₂ phases in AZ80 magnesium alloy was studied by multi-directional forging (MDF) with decreasing temperatures from 410 to 300 °C. The results show that the morphology of the dynamically precipitated β-Mg₁₇Al₁₂ phases (formed during forging process) exhibited granular shape. During the multi-directional forging process, the inhomogeneous dynamic precipitation of the β-Mg₁₇Al₁₂ phases result in the coexistence of the fine grains (with many granular Mg₁₇Al₁₂ phases) and coarse grains (without Mg₁₇Al₁₂ phases) in the samples. The fine grains (with many granular Mg₁₇Al₁₂ phases) area expands with the decreasing of final forging temperature. The inhomogenous Al content distribution in the Mg matrix leads to the non-uniform dynamic precipitation of the Mg₁₇Al₁₂ phase. These Mg₁₇Al₁₂ phase retards the growth of the DRX grains, which in turns results in the formation fine grains area during the during the MDF process with temperature decreasing.