HOT COMPRESSION DEFORMATION BEHAVIOR AND CONSTITUTIVE ANALYSIS OF EXTRUDED MAGNESIUM-BISMUTH ALLOYS

The isothermal compression experiments of Mg-2Bi alloys were carried out under different temperature and strain rate by Gleeble 3500D thermal simulation test machine. The rheological stress variation law of the Mg-2Bi alloy was analysed under 200-350oC and 0.001-1.0 s-1. The results present that the peak stress enhances and the dynamic recrystallization grain size reduces with the decline of deformation temperature and the improvement of strain rate during isothermal compression of the Mg-2Bi alloy. In addition, the activation energy for alloy deformation is 130.03 kJ/mol. The softening mechanism of the Mg-2Bi alloy is mainly twin and dynamic recrystallization under a low temperature (200oC) condition. While at a higher temperature of 350oC, the softening mechanism changes to single dynamic recrystallization.