Deformation mechanisms and plastic anisotropy in magnesium alloy AZ31

The magnesium alloy AZ31 shows a significant drop in the normal anisotropy between room temperature and ∼200 °C. It has been suggested in the literature that this drop could be the result of grain boundary sliding (GBS). This paper further examines the notion of GBS at these temperatures through observation of surface relief, grain boundary shearing, and quantification of intergranular and intragranular strain distributions. It was found that there is negligible grain boundary sliding at any test temperature. The only significant change in deformation behaviour between 25 and 150 °C is an increase in the homogeneity of slip at the higher test temperature. It is concluded that the drop in normal anisotropy with increased test temperature is unlikely to result from GBS, and more likely to be the result of an increase in pyramidal slip activity at higher test temperatures.