Effects of trace amounts of Zr and Sc on the recrystallization behavior and mechanical properties of Al-4.5Zn-1.6Mg alloys

The effects of Zr and Sc on the recrystallization behavior and mechanical properties in Al-4.5Zn-1.6Mg alloy were investigated to understand the strengthening mechanism and to improve the mechanical properties. The results show that the Al-4.5Zn-1.6Mg alloys without the Zr and Sc addition obtained a coarse grain structure; the addition of 0.1% Zr to the Al-4.5Zn-1.6Mg alloy, made it possible to inhibit the grain growth; the addition of 0.1% Sc led to better inhibition to recrystallization through fine precipitates of coherent Al₃Sc phases. The precipitation of coherent Al₃Sc particles acted to strongly pin the grain boundaries, thereby effectively restraining their migration leading to the higher strength of the Sc-containing Al-4.5Zn-1.6Mg alloy.