Electrochemical co-reduction of Y(III) and Al(III) in a fluoride molten salt system and electrolytic preparation of Y–Al intermediate alloys

In this study, a molten salt co-reduction method was proposed for preparing Y–Al intermediate alloys and the electrochemical co-reduction behaviors of Y(III) and Al(III) and the reaction mechanism of intermetallic compound formation were investigated by transient electrochemical techniques. The results show that the reduction of Y(III) at the Mo electrode is a reversible electrochemical process with a single-step transfer of three electrons, which is controlled by the mass transfer rate. The diffusion coefficient of Y(III) in the fluoride salt at a temperature of 1323 K is 5.0238 × 10 –3 cm 2 /s. Moreover, the thermodynamic properties associated with the formation of Y–Al intermetallic compounds are estimated using a steady-state electrochemical method. Y–Al intermediate alloy containing 92 wt% yttrium is prepared by constant current electrolysis at 1323 K in the LiF–YF 3 –AlF 3 –Y 2 O 3 (6 wt%)–Al 2 O 3 (1 wt%) system at a cathodic current density of 8 A/cm 2 for 2 h. The Y–Al intermediate alloy is mainly composed of α–Y 2 Al and Y phases. The development and application of this innovative technology has solved major technical problems, such as a long production process, high energy consumption, and serious segregation of alloy elements at this stage. The cathodic behavior of Y(III) at a Mo electrode and the electrochemical co-reduction behavior of Y(III) and Al(III) at the Mo electrode were investigated by different electrochemical methods. The electrochemical signals generated by Y–Al intermetallic compounds are detected, and the formation of the intermetallic compound YAl 1/2 by the underpotential deposition of Y(III) on an inert electrode was confirmed. Y–Al intermediate alloy containing 92 wt% yttrium is prepared by constant current electrolysis at 1323 K in the LiF–YF 3 –AlF 3 –Y 2 O 3 (6 wt%)–Al 2 O 3 (1 wt%) system at a cathodic current density of 8 A/cm 2 for 2 h.