Formation Mechanism and Preparation of YAl 2 Intermetallics by Electro-Deoxidation with Different Sintering Conditions

A study was carried out on the preparation of YAl2 intermetallics from mixed oxide precursors using the method of electro-deoxidation. Y2O3 and Al2O3 mixed in molar proportions of 1:2 were sintered at temperatures ranging from 800 to 1200 °C for different hours. The sintered pellet was then electrolyzed in a molten CaCl2 at 850 °C using a graphite anode at a potential of 3.1 V. In this work, effects of sintering on the composition and the oxygen content in cathodic products were studied by X-ray diffraction (XRD) and oxygen–nitrogen analyzer. Sintering mainly affects the porosity of the pellets, and it is found that porosity decreases gradually with the increase in sintering temperature and the extension of sintering time. When sintered at 900 °C for 4 h, the oxygen content in the cathodic product decreases to 1.85 wt%, and the efficiency of electro-deoxidation is 94.48%. At the same time, the mechanism of electrolysis was speculated. The results suggest that the formation of YAl2 is a multi-step process. During the reduction process from mixed oxides Y2O3/Al2O3 to YAl2 included many intermediate materials, such as YAlO3, Y3Al5O12 and YAl3, YAl2 intermediate alloy was prepared finally.