Grain refinement and improved age hardening of Mg–Zn alloy by a trace amount of V

A microalloying addition of V acts as an effective grain refiner of Mg–Zn alloy. V exhibits limited but noticeable solubility in solid magnesium alloyed with Zn. V is exceptionally effective in promoting the nucleation of precipitates during age hardening and it also markedly accelerates the kinetics of precipitation. A near-peak hardness value can be reached after only 4 h of ageing at 160 °C. A considerably higher number density of the precipitates forms in Mg–Zn–V alloy as compared to Mg–Zn, resulting in a doubling of the hardness increment produced by artificial ageing. The highest level of hardening is achieved by ageing at intermediate temperatures. Natural ageing in Mg–Zn–V alloy is notably accelerated compared to that of the binary alloy. The details of the mechanisms involved with grain refinement and enhanced nucleation of precipitates by V are yet to be clarified.