Mechanical alloying of Zn-rich Zn-Al-Cu alloys

Zn-rich Zn-Al-Cu alloys were produced by milling of elemental powders mixtures, Zn-22 wt.% Al-3 wt.% Cu and Zn-20 wt.% Al-10 wt.% Cu, for times of up to 1080 ks. The X-ray diffraction analysis showed the formation of α (aluminum-rich), η (zinc-rich) and ε (CuZn ₄) phases at the early stage of milling. The presence of ε phase was more evident with the increase of copper content in mixture. In the case of the two alloy compositions, the following phase transformation α + ε → η + τ′ was observed to occur during milling. A mixture of η, α and τ′ phases was found in powder mixtures milled for 1080 ks, which is in agreement with phases predicted for these compositions in the equilibrium Al-Cu-Zn phase diagram. Finally, all these phases were present on a nanometer scale in both mechanically alloyed powders.