Effect of compression conditions on the microstructure and texture of a Mg–RE alloy

Abstract

The effect of compression conditions on the microstructure and texture of a Mg–8Gd–4Y–1Nd–0.5Zr alloy has been investigated by hardness test, optical microscopy, scanning electron microscopy and electron backscatter diffraction. The post-deformed grain size is directly influenced by the area fraction and the distribution of RE-rich particles. A uniform microstructure of refined grains is accompanied by randomly distributed particles due to particle pinning, while a bimodal grain structure is attributed to the dissolution of particles during compression. The textures of all compressions are weak and the dominant component changes with the compression condition. Compression at temperature 450°C and a low strain rate of 0.0003s−1, the texture is a result of dynamic recrystallization (DRX), such as discontinuous DRX (DDRX) and particle stimulated nucleation (PSN), and grain boundary sliding. The alloy exhibits a typical basal texture of 〈0001〉//ND (the normal direction) after compression at temperature 500°C and a strain rate of 0.2s−1, which suggests that RE-rich particles rather than the high concentration of RE solute atoms in the matrix are necessary to generate the weak and randomized texture during hot compression of the studied alloy.