Zinc-aluminium castings alloys containing 8-30 % AL

The work concentrates to study the solidification sequence of Zn-Al alloys having various compositions. The effects of the basic composition, cooling rate and melt treatment on a cast microstructure is studied. In addition the connection between the composition, microstructure, castability and mechanical properties is discussed. The results show that, when the aluminium content is high, it is poss-ible to achieve good mechanical properties. However, the castability of alloys alloyed with more than 15 % Al is not good due to their inferior fluidity and pronounced gravity segregation. Castability can be improved by treating the melt by alloys containing titanium or/and boron