Materials processing for structural stability in a ZK60 magnesium alloy

The materials processing, consisted of a four step process of solution treatment, pre-strain, overaging and hot working, was developed for attaining structural stability at high temperatures in a commercial Mg-Zn-Zr alloy, ZK60. The grain size of the material processed by this schedule was refined to 2.5 mum, and the material behaved in a superplastic manner at 548 K and at a strain rate of 1 x 10(-2) s(-1) owing to the grain size stability at this temperature. From the analysis of the chemical composition of precipitates, it was suggested that the phase Mg-7(Zn,Zr)(3), which was not observed in material without pre-strain, was effective in pinning the grain boundaries at high temperatures.