DEFORMATION BEHAVIOR AND DYNAMIC RECRYSTALLIZATION OF MICROALLOYED 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 designedbased on the thermodynamics calculation in terms ofprecipitation temperature. Hot compression tests wereconducted at temperatures of 300°C, 350°C and 400°C withstrain rates of 0.1s~(-1), 0.01s~(-1) and 0.001s~(-1). Dynamic precipitationof Al2Ca could be found below 400°C in AX0302, whileMg2Ca dynamically formed in AX0105 during deformation atall 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)), DRXmainly developed at the grain boundaries and formed necklacetype microstructure in both alloys. However, at lowertemperature and higher strain rate, DRX grains formed at bothgrain boundaries and twinning boundaries. The combinationeffect of twinning and dynamic precipitation on dynamicrecrystallization was studied by comparing with two alloys.