Mechanical properties, microstructure, and solidification characteristics of Mg-Zn-Al alloys

In this work, three experimental alloys, Mg-14%Zn-2%Al (ZA142), Mg-14%Zn-4%Al (ZA144), and Mg-t4%Zn-6%Al (ZA146) were cast and their microstructure and properties characterised. The results show that ZA142 consists of alpha(Mg), and two intermetallic compounds, epsilon; (MgZn), and tau (Mg-32(Al,Zn)(49)). The intermetallic phase observed in ZA144 is tau, whereas the experimental alloy ZA146 is composed of alpha(Mg), phi (Al2Mg5Zn2), and a small amount of tau. The solidification range of these experimental alloys is greater than 230degreesC, increasing with a reduction of Al content. Among these three alloys, the ZA144 shows the best creep resistance, which is substantially superior to that of the well known AZ91 magnesium alloy. However, the elongation of these experimental alloys is less than that of AZ91.