Grain refinement, texture, and mechanical properties of a magnesium alloy after radial-shear rolling

Microstructure (including its uniformity), texture, and mechanical properties of Mg-Al-Zn-Mn alloy billets after radial-shear rolling (RSR) were investigated. RSR with the temperature in the interval 420 -140 degrees C and true strain up to 2.63 was shown to lead to grain refinement down to 1.5-3.5 mu m (as determined by optical microscopy). The microstructure was found to be reasonably uniform over the transversal cross-sections of the billets. The transmission electron microscopy analysis also revealed submicron sized grains and the formation of two types of particles: Mg17Al12 particles 300-500 nm in size and MgAl nanoparticles of different shapes 20-40 nm in size. Increments in strain and step-wise decrease in deformation temperature with the number of RSR passes was found to lead to a transformation of the initial basal texture to the prismatic texture. The RSR of the Mg-Al-Zn-Mn magnesium alloy was demonstrated to result in significant strength and good ductility owing to a fortunate interplay between fine grain structure and favorable texture promoting activity of non-basal slip systems. (C) 2018 Elsevier B.V. All rights reserved.