Electrodeposition of Cu-Al Alloys and Underpotential Deposition of Al onto Cu Single Crystals from a Room-Temperature Chloroaluminate Molten Salt

Published

January 1, 2000

Author(s)

Gery R. Stafford, V D. Jovic, C L. Hussey

Abstract

The electrodeposition of Cu-Al alloys, as well as underpotential deposition (UPD) of Al onto Cu(111), Cu(100) and Cu(110) faces, were investigated in the Lewis acidic aluminum chloride/1-methyl-3-ethyl-imidazolium chloride. It was shown that it is possible to produce Cu-Al alloy deposits at potentials positive of that corresponding to the electrodeposition of bulk Al ({approximately equal to} 0.V). For a 0.05 mol dm^-3 solution of Cu(1), the onset of the Al codeposition process was found to occur at around 0.30 V versus the Al(111)/Al couple; however, a limiting current for the reduction of Cu(1) to pure Cu metal can be observed in the 0.60 V to 0.30 V potential interval in this solution. The Cu-Al alloy composition was found to be independent of the Cu(1) concentration, reaching a maximum value of 43 atomic percent (a/o) Al at 0 V. X-ray diffraction studies induicated that Cu-Al deposits containing about 7.2 a/o Al retained the fcc Cu structure; however, deposits containing 12.8 a/o Al were two-phase with the second phase tentaively indentified as martensitic Β'-Cu₃Al. This phase appears to form before fcc Cu becomes saturated with Al. Cyclic voltammograms recorded onto Cu(111), Cu(100) and Cu(110) clearly indicate that UPD of Al commences at about 0.3 V vs. Al. On the (111) face of Cu UPD takes place through two sharp and separated peaks, indicating formation of two different adsorbed structures, with the second peak corresponding to the formation of a monolayer of Al. Surface alloying of Cu with Al was detected at potentials of the first peak ({approximately equal to} 0.25 V vs. Al).

Citation

Advanced Materials Research

Volume

352

Pub Type

Journals

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Keywords

Cu-Al, electrodeposition, molten salt, phase composition, room temperature, UPD of Al

Citation

Stafford, G. , Jovic, V. and Hussey, C. (2000), Electrodeposition of Cu-Al Alloys and Underpotential Deposition of Al onto Cu Single Crystals from a Room-Temperature Chloroaluminate Molten Salt, Advanced Materials Research, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852958 (Accessed April 24, 2024)