Study on dynamic recrystallization of Mg-Gd-Nd-Zr magnesium alloy under hot deformation
Using the Gleeble-3800 thermal simulated test machine,thermal compression tests on Mg-Gd-Nd-Zr magnesium alloys were performed at deformation temperatures ranging from 350℃ to 500℃,with strain rates of 0.003～1 s-1and strain of 0.7.Based on the work hardening rate,dynamic recrystallization of the alloy under hot deformation was investigated using optical microscopy and transmission electron microscopy.The results of this study show that the alloy exhibits typical dynamic recrystallization characteristics under hot deformation,with great sensitivity to temperature and strain rate.The increase in thermal compression temperature and the decrease in strain rate boost dynamic recrystallization.The recrystallization involves three mechanisms:bulging nucleation of grain boundary migration,continuous dynamic recrystallization and the second-phase induced nucleation.Then along with the increase of strain rate and the decrease of temperature,the critical strain of dynamic recrystallization of the alloy increases,and the established model of critical strain is εc=3.061 x 10-6 × Z0.2482.
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