Electrodeposition of Copper and Copper-Aluminum Alloys From a Room-Temperature Chloroaluminate Molten Salt

Published

September 1, 1998

Author(s)

B J. Tierney, W R. Pitner, J A. Mitchell, C L. Hussey, Gery R. Stafford

Abstract

The electrodeposition of copper and copper-aluminum alloys was investigated in the Lewis acidic aluminum chloride-1-methyl-3-ethylimidazolium chloride [60.0-40.0 mole percent (m/o)] molten salt containing electrogenerated Cu(I) at 40 + 1 degree Celsius}. Sampled current and rotating ring-disk electrode voltammetry experiments indicated that it was possible to produce Cu-Al alloy deposits at potentials positive of that corresponding to the electrodeposition of bulk aluminum (O V). For a 5.0 x 10^-2 mol L^-1 solution of Cu(I), the onset of the aluminum codeposition process was found to occur at around 0.30 V versus the Al(III)/ Al couple; however, a limiting current for the reduction of Cu(I) to pure copper metal can be observed in the 0.60 to 0.30 V potential interval in this solution. The Cu-al alloy composition was found to be independent of the Cu(I) concentration, reaching a maximum value of 43 atomic percent (a/o) aluminum at O V. The surface morphology of bulk Cu-Al alloy electrodeposits was highly dependent on the aluminum content; pure copper deposits had a dense, nodular appearance, whereas deposits containing appreciable amounts of aluminum consisted of fragile dendrites. X-ray diffraction studies indicated that Cu-Al deposits containing about 7.2 a/o Al retained the fcc copper structure; however, deposits containing 12.8 a/o Al were two-phase with the second phase tentatively identified as martensitic Β'-Cu₃Al. This phase appears to form before fcc copper becomes saturated with aluminum.

Citation

Journal of the Electrochemical Society

Volume

145

Pub Type

Journals

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Keywords

copper, copper-aluminum alloys, electrodeposition

Citation

Tierney, B. , Pitner, W. , Mitchell, J. , Hussey, C. and Stafford, G. (1998), Electrodeposition of Copper and Copper-Aluminum Alloys From a Room-Temperature Chloroaluminate Molten Salt, Journal of the Electrochemical Society, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852878 (Accessed April 26, 2024)