Dynamic precipitation during high-pressure torsion of a magnesium-manganese alloy

Abstract

An ultrafine grained magnesium alloy has been produced through room temperature high-pressure torsion (HPT) of solutionised Mg-1.35 wt.%Mn. Dynamic precipitation of nanometer-scale Mn particles occurred during deformation. These particles populated the grain boundaries, acting as pinning sites which allowed the alloy to develop a grain size of 140 nm after 0.5 rotations. Further HPT deformation resulted in a gradual increase in grain size with no increase in precipitate size. Despite the extensive deformation applied, the alloy did not develop a bimodal grain structure and retained a grain size of 230 nm after 10 complete rotations, demonstrating the stability and effectiveness of these pinning particles.