Precipitation behavior of an ultra-fine grained Mg-Zn alloy processed by high-pressure torsion

Precipitation behavior in severely plastically deformed Mg-3.4 at%Zn was studied by ageing treatment at 348 and 423 K. Microstructural observations reveal two kinds of precipitates: one from the dynamic precipitation during high-pressure torsion processing and the other from the ageing treatment. Precipitates formed from annealing treatment are observed inside of grains after 4 h of annealing at 423 K, while they were not observed at 348 K. Effect of precipitation hardening is balanced by the grain growth and formatidn of precipitates free zones at ageing temperature of 423 K, resulting in the absence of age-hardening effect in ultra-fine grained MgZn prepared by severe plastic deformation. Published by Elsevier B.V.