Strain dependency of dynamic recrystallization during thermomechanical processing of Mg-Gd-Y-Zn-Zr alloy

Abstract

The microstructure and microtexture of an extruded and annealed GWZ (Mg-8.2Gd-3.6Y-1.6Zn-0.5Zr, wt.%) magnesium alloy was recorded strain by strain in the course of thermomechanical processing. The specimens were compressed down to various interruption strains of 0.1, 0.3, and 0.5 under the strain rate of 0.001 s−1 at 400 °C, the temperature at which the material was capable to be recrystallized extensively. Appreciable refinement was recognized even at low imposed compressive strain of 0.1, and the recrystallization process was completed at true strain 0.3 where the mean grain size of 4.3 μm was attained. The LPSO stimulated nucleation (LSN) and conventional continuous dynamic recrystallization (CDRX) mechanism were contributed in grain refinement. Consequently, the initial basal texture was considerably weakened which was mainly ascribed to the formation of RE-texture components. At higher imposed strain of 0.5, the majority of grains were found in deformed states, the capability of strain softening was decreased and the microtexture only changed in respect of intensity compared with true strain of 0.3. These indicated that the imposed strain was mainly accommodated through dislocation multiplication and tangling within the previously recrystallized grains. Complementary, the slip/twin activity, and the sequence of strain accommodation was investigated through Schmid analysis of the various systems.

Keywords

• GWZ magnesium alloys
• LPSO
• Dynamic recrystallization
• Thermomechanical processing
• Microtexture