Abstract: The cyclic voltemmetry method was used to investigate the electrochemical behaviors of Y（Ⅲ）,Mg（Ⅱ）and Co（Ⅱ） in Y(NO3)3-LiClO4-DMF,Mg(ClO4)2-LiClO4-DMF and CoCl2-LiClO4-DMF systems on Pt cathode. Experimental results indicate that the electro-reduction of Y（Ⅲ）,Mg（Ⅱ）and Co（Ⅱ） to Y、Mg and Co is an one-step irreversible in process. The diffusion coefficient and transfer coefficient of Y（Ⅲ）in Y(NO3)3-LiClO4-DMF system at 301 K are 1.68×10－5 cm2•s－1,0.10; Mg(Ⅱ)in Mg(ClO4)2-LiClO4-DMF system at 301 K are 2.95×10－6 cm2•s－1,0.11; Co(Ⅱ) in CoCl2-LiClO4-DMF system at 301 K are 1.34×10－5 cm2•s－1 and 0.24 respectively. Y-Mg-Co alloy films containing Y from 3.88％ to 58.66％ and Mg from 4.51％ to 17.52％ were prepared by potentiostatic electrodeposition on Cu substrate with deposition potential ranging from －1.50 V to －3.00 V(vs SCE).Their surface morphologies were smooth, adhesive, uniform and have metallic luster.

Key words: Yttrium, Potentiostatic electro-deposition, Y-Mg-Co alloy, Diffusion coefficient, Transfer coefficient