Constitutive Modelling of Hot Deformation Behavior of Extruded Mg-0.5Zn-<0.1Gd-0.5Y-<0.1Nd Alloy

The high temperature deformation behavior of a new dilute Mg alloy was investigated by hot compression tests in the temperature and strain rate range of 375-450°C and 0.001-1 s-1, respectively. The stress-strain curves and microstructure of the hot deformed samples were studied carefully by means of optical microscopy. The stress-strain behavior categorized dynamic recrystallization and dynamic recovery. Microstructural observation revealed serration of grain boundaries up to the strain rate of 0.1s-1. At the strain rate of 1s-1, a strong twinning induced necklace structure was the most significant characteristic. These twins caused a decrease in the average grain size by the increase of strain rate. Based on the measured stress-strain data, constitutive model was obtained for the alloy and presence of alloying elements resulted in an increase of the Q- value to 366 kJmol-1.