DEFORMATION BEHAVIOR AND DYNAMIC RECRYSTALLIZATION OF MICRO-ALLOYED Mg-Al-Ca ALLOYS DURING HIGH TEMPERATURE DEFORMATION

摘要

Two micro-alloyed magnesium alloys, Mg-0.3Al-0.2Ca (AX0302) and Mg-0.1Al-0.5Ca (AX0105), were designed based on the thermodynamics calculation in terms of precipitation temperature. Hot compression tests were conducted at temperatures of 300°C, 350°C and 400°C with strain rates of 0.1s"1, 0.01s"1 and 0.001s"1. Dynamic precipitation of Al_2Ca could be found below 400°C in AX0302, while Mg_2Ca dynamically formed in AX0105 during deformation at all three temperatures. At high temperature and low strain rate (400°C at 0.01s"1 and 0.001s"1 and 350°C at 0.001s~(-1)), DRX mainly developed at the grain boundaries and formed necklace type microstructure in both alloys. However, at lower temperature and higher strain rate, DRX grains formed at both grain boundaries and twinning boundaries. The combination effect of twinning and dynamic precipitation on dynamic recrystallization was studied by comparing with two alloys.