Optimization of processing parameters for preparation of Al-3Ti-1B grain refiner

Al-3Ti-1B master alloys were prepared at different processing parameters by the reaction of halide salts, and the grain refining response of Al-7Si alloy was investigated with Al-3Ti-B master alloy. The microstructure of master alloy and its grain refining effect on Al-7Si alloy were investigated by means of OM, XRD and SEM. Experimental results show that, the size of Al3Ti particles presented in Al-3Ti-1B master alloys increases with the increase of reaction temperature and decreases with the increase of cooling rate. The grain refining efficiency of Al-3Ti-1B master alloy on Al-7Si alloy is mainly attributed to heterogeneous nucleation of Al3Ti particles, and the morphology of α(Al) changes from coarse dendritic to fine equiaxed. As a result, Al-3Ti-1B master alloy is prepared by permanent mold, and holding at 800 °C for 30 min, which has better grain refining performance on Al-7Si alloy.