The effects of Ti and Sr on the microstructures of Al-11.3 wt.%Si alloys produced by the ohno continuous casting process

Abstract

An investigation has been conducted to describe the effect of Ti grain refiner or Sr modifier on the microstructure of an Al-11.3 wt.%Si alloy produced by the Ohno horizontal continuous casting process so as to obtain directional solidification at high cooling rates. Experimental results demonstrated that the directionality of the primary grains were promoted by the addition of 0.2 to 0.4%Ti or by the addition of 0.02%Sr, whereas the addition of 0.6%Ti suppressed this directionality. Feathery grains were promoted by the addition of 0.2%Ti, while these feathery grains were suppressed when over 0.4%Ti or when 0.02%Sr was added. The addition of Ti also resulted in increased coarsening of the eutectic Si in these Al-11.3 wt.%Si alloys.