Effect of La2O3 on the Microstructure and Grain Refining Effect of Novel Al-TiO2-C-XLa2O3 Refiners

Abstract

New aluminum grain refiners, Al-TiO2-C-XLa2O3 refiners, were manufactured by the in situ reaction of Al powder, TiO2 powder, C powder, and La2O3 powder. The effects of La2O3 on the refiners’ microstructure and the grain refining effect of the Al-TiO2-C-XLa2O3 refiners on industrial aluminum were studied. The effect of the sintering process was also studied. The results show that the refiners contain Al3Ti, TiC, Al2O3, AlN, and Al20Ti2La. As the content of La2O3 increases, the amount of Al20Ti2La also increases. However, the amounts of Al3Ti, Al2O3, and TiC decrease. Al3Ti is a lath-like compound whose size becomes smaller. The distribution of Al2O3 and TiC, however, is more uniform. The Al-TiO2-C-0.2La2O3 refiner has the best grain refining effect on industrial aluminum. The size of the industrial aluminum refined by the Al-TiO2-C-0.2La2O3 refiner is 320 μm; the refiner’s grain size is 8.4% that of the industrial aluminum without refiners 0 μm (380). After adding the novel Al-TiO2-C-0.2La2O3 refiner, the nucleation temperature TN reached 679.21 °C, which is 17 °C above the nucleation temperature of the industrial aluminum without refiners. The primary transformation time is the longest at 25.5 s, which is 4.6 s higher than that of industrial aluminum (20.9 s). Furthermore, the ΔT of the aluminum is 0.5 °C, which is the lowest value.