EFFECTS OF SQUEEZE CASTING ON THE PROPERTIES OF ZN-BI MONOTECTIC ALLOY

In composite production, the shortest route is via an in situ composit e in which a melt dissociates simultaneously into two rather different solid phases. The monotectic alloys can be included in this group. Th e present work was aimed at extending our recent squeeze casting exper ience on the Zn-Bi monotectic alloy in order to increase its cast qual ity and mechanical properties. A squeeze casting unit was built, and i ts die and punch were machined. The molten monotectic alloy was squeez ed in this unit under pressures up to 120 MPa in its freezing range un til it solidified completely. It was found that an increase in squeeze casting pressure provided increases in density, tensile strength, and Vickers hardness, which resulted in decreases in chip length and elec trical resistivity. Before the squeeze casting practice, the freezing characteristics of this monotectic were estimated using basic solidifi cation principles.