Role of temperature and precipitates on the evolution of microstructure and texture during grain growth of Mg-3Al-0.2Ce alloy

摘要

Mg-3Al-0.2Ce alloys were subjected to annealing at temperatures ranging from 200 to 450 degrees C for different periods to evaluate the microstructure and texture developments in the alloy. The grain growth exponent of n = 13 and the activation energy for grain growth, Q = 75 kJmol(-1) were observed. A large number of precipitates were observed in the samples. They were found to be Mg17Al12, Al8Mn5, Al11Mn4, Al11Ce3, Al3Ce, Al4Ce, Mg17Ce2, Al10Mn7Ce2, Mg2Ce, Mg3Ce, and Mg12Ce, as confirmed by electron probe microanalysis (EPMA) and X-ray Diffraction (XRD). The precipitates were further found to be dissolved or disappeared with an increase in the temperature of annealing. As a result, the grain boundary mobility was enhanced during annealing at high temperatures and increased the grain growth of the samples. The initial basal texture in the alloy was observed to be tilted (by similar to 30 degrees) towards the transverse direction of the samples during annealing. Such a texture weakening in the alloy during annealing was attributed to the nucleation and growth of new grains formed in the deformed zone surrounding the precipitates.