The Effect of ECAP Temperature on the Microstructure and Properties of a Rolled Rare Earth Magnesium Alloy

Deformation of an as-rolled rare earth Mg-2Y-0.6Nd-0.6Zr alloy, at different temperatures, was carried out along the BC (90 degrees anticlockwise rotation of the samples after each ECAP pass) route by equal channel angular pressing (ECAP). The effects of the deformation temperature and the predeformation on the microstructure of the magnesium alloy were determined by the microstructure examination. The slip systems and texture change of the Mg-2Y-0.6Nd-0.6Zr alloy were investigated by X-ray diffraction (XRD) and electron backscattered diffraction (EBSD), after equal channel angular deformation. The results showed that after seven passes of rolling, the grain size in the Mg-2Y-0.6Nd-0.6Zr alloy was refined to approximately 22 mu m and the slip occurred mainly by a cylindrical slip and a pyramidal slip. After one pass of ECAP at 340 degrees C, the internal average grain size was significantly reduced to 11 mu m, the cylindrical diffraction intensity clearly weakened, and the pyramidal diffraction intensity increased. EBSD pole figure analysis revealed that the base texture of the rolled Mg-2Y-0.6Nd-0.6Zr alloy weakened from 24.31 to 11.34 after ECAP. The mechanical properties indicated that the tensile strength and elongation of the rolled Mg-2Y-0.6Nd-0.6Zr alloy reached maximum values, when the deformation temperature was 340 degrees C.