Effects of thermomechanical processing on the microstructure, texture and mechanical properties of a Mg-Gd-based alloy

Abstract

The effect of thermomechanical processing on the microstructure, texture and mechanical properties of a Mg-5.5Gd-3.0Y-1.0Nd-1.0Zr (wt.%) alloy was investigated using optical microscopy, uniaxial tensile testing, hardness testing, scanning electron microscopy, transmission electron microscopy, texture testing and X-ray diffraction. An overaging treatment before extrusion was introduced to affect the dynamic recrystallization process of the alloy. The results indicate that a substantial amount of β equilibrium phases with the composition of Mg5.05RE (RE: rare earth) precipitated from the matrix during the aging process prior to extrusion. Compared to the counterpart with no precipitates, the dynamic recrystallization process was promoted by the mechanism of particle-stimulated nucleation, which led to the formation of uniform fine grains and weakened texture in the extruded rod. Samples with an ultimate tensile strength of 324 MPa and a good elongation of 20.5% were obtained. The good ductility was attributed to the uniform fine grains and the modified texture.