Formation mechanism and preparation of YAl_(2) intermetallics by electro-deoxidation with different sintering conditions

摘要

A study was carried out on the preparation of YAl_(2) intermetallics from mixed oxide precursors using the method of electro-deoxidation.Y2O_(3) and Al_(2)O_(3) mixed in molar proportions of 1:2 were sintered at temperatures ranging from 800 to 12000C for different hours.The sintered pellet was then electrolyzed in a molten CaCl_(2) at850℃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 9000C 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 YAl_(2) is a multi-step process.During the reduction process from mixed oxides Y2O_(3)/Al_(2)O_(3) to YAl_(2) included many intermediate materials,such as YAlO_(3),Y3Al5O12 and YAl3,YAl_(2) intermediate alloy was prepared finally.