The role of recrystallization and grain growth in optimizing the sheet texture of magnesium alloys with calcium addition during annealing

摘要

The contribution of recrystallization and grain growth to the texture evolution in AZ31 alloy and a modified version AZ31+0.5 wt.%Ca was investigated utilizing a multi-step annealing process.The results showed that the addition of Ca triggered a considerable texture modification by increasing the texture spread and decreasing the overall texture intensity.This effect was found to be temperature dependent.When the annealing temperature remained lower than 450℃,a weak double peak texture with large basal pole tilt towards the RD was formed.This is correlated to microstructure observations of a large number of Ca-containing nano-sized particles that seemed to suppress grain growth below 450℃,which stabilized the weak recrystallization texture.This favorable texture was lost upon annealing at higher temperatures.In AZ31,recrystallization nuclei were found to preserve the orientation of their deformed parents,which offered limited potential to optimize the texture via annealing treatments.Grain growth of recrystallized grains resulted in a distinct sheet texture transition from a double-peak to a single-peak basal texture.Aspects of grain boundary energy and grain topology are discussed to explain the growth advantage of the sharp basal component over other orientations.