EFFECTS OF SQUEEZE CASTING ON THE WIDE FREEZING RANGE BINARY-ALLOYS

The application and effects of squeeze casting were investigated on th e density, Brinell hardness, tensile strength and fracture elongation values of the wide freezing range Zn-27%Al, Al-20%Si, Al-7%Si, Al-1O%M g, Al-S%Mg, Al-4.5%Cu-0.5%Bi and Fe-3%C-2%Si alloys. It was found that these alloys as a group were suitable for the squeeze casting practic e. Sharp increases could be achieved in all mechanical properties due to the reductions in porosity levels. In general, higher squeezing pre ssures provided better mechanical properties. The trend in the Al-20%S i alloy however, was sporadic and cracking occurred in the vicinity of silicon rich primary particles above 100 MPa pressure. An optimum mel t, and die and punch temperatures were found as 1500 degrees C and 115 0 degrees C, respectively to suppress white cast iron formation in the Fe-3%C-2%Si ahoy. The Al-10%Mg and Al-4.5%Cu-0.5%Bi alloys suffered m icrosegregation in addition to microporosity. Their squeeze cast sampl es showed higher hardness and tensile properties after annealing them. The machinabilities of the two alloys however, were degraded due to s queeze casting.