Electrochemical formation of Ni-Y intermetallic compound layer in molten chloride

• Published in: Journal of applied electrochemistry 1993-07, Vol.23 (7), p.753-759
• Main Authors: XIE, G, EMA, K, ITO, Y, ZHAO MIN SHOU
• Format: Article
• Language: English
• Subjects: Chemistry; Electrochemistry; Exact sciences and technology; General and physical chemistry; High temperature electrochemistry (including molten salts)
• ISSN: 0021-891X; 1572-8838
• DOI: 10.1007/bf00243346

The reduction of Y(III) ions in molten chloride is known to be a one-step three electron reaction [1, 2, 3], but a voltammogram of YCl sub 3 in molten LiCl--KCl--NaCl at a nickel electrode shows at least two reduction peaks of Y(III) ions, indicating the possibility of formation of Ni--Y intermetallic compounds. Using a galvanostatic electrolysis method, samples were prepared at several current densities at 450, 500, 600 and 700 deg C, respectively, and were identified with X-ray diffraction (XRD) and electron probe microanalysis (EPMA) methods. The results show that Ni sub 2 Y, Ni sub 2 Y sub 3 and NiY can be produced by electrolysis and Ni sub 2 Y is found to be the predominant Ni--Y intermetallic compound under the experimental conditions. Nickel appears to diffuse in Ni sub 2 Y faster than yttrium, and the diffusion process is the rate determining step during Ni sub 2 Y formation.