Preparation of Al–Hf master alloy by aluminothermic reduction of HfO2

The Al–Hf alloy was prepared by open aluminothermic reduction of HfO 2 using CaF 2 and NaF as the flux. The influence of the slag composition, the amount of aluminum, and the heat energizer was studied detailly to establish optimum conditions for the sufficient recovery of the alloy and the complete slag–alloy separation. The Al–Hf alloy with 40 wt% Hf was obtained by this method, and the maximum recovery was 70.7%. The microstructure of the alloy was observed by scanning electron microscope (SEM). Moreover, X-ray diffraction (XRD) analysis and energy-disperse spectrometry (EDS) were applied to characterize the formation of the phases. The results show that the alloy consists of Al and Al 3 Hf phases and the oxygen content is about 0.2 wt%.