Materials Processing for Structural Stability in a ZK60 Magnesium Alloy

Abstract

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 μm, and the material behaved in a superplastic manner at 548 K and at a strain rate of 1×10−2 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 Mg7(Zn,Zr)3, which was not observed in material without pre-strain, was effective in pinning the grain boundaries at high temperatures.