Electrodeposition of Al-W Alloys in the Lewis Acidic Aluminum Chloride-1-Ethyl-3-Methylimidazolium Chloride Ionic Liquid

Published

April 24, 2014

Author(s)

Tetsuya Tsuda , Yuichi Ikeda , Takashi Arimura, Masaki Hirogaki, Akinito Imanishi, Susumu Kuwabata, Gery R. Stafford, Charles Hussey

Abstract

The electrodeposition of non-equilibrium Al-W alloys was investigated in the Lewis acidic 66.7-33.3 % mole fraction aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl_(3)-[EtMeIm]Cl) room-temperature ionic liquid (IL). The W(III) compound, K_(3)[W_(2)Cl_(9)], served as the reservoir for W. Both controlled potential and controlled current techniques were employed. Depending on the electrodeposition conditions, it was possible to prepare Al-W alloys with a W content approaching 96 % atomic fraction (a/o). However, as the W content of these alloys increased above 30 a/o, the deposits became powdery and friable and were difficult to characterize. XRD analysis of deposits containing 16 a/o W revealed a broad reflection consistent with the amorphous phase that typically appears at alloy concentrations that exceed the limit of the supersaturated solid solution. This phase is not readily apparent in x-ray diffraction patterns until the W content reaches about 9 a/o. As expected, the lattice parameter for the fcc Al phase decreased as the W content of the alloy increased, reaching a maximum contraction of about 0.2 %, consistent with a W content of about 5 a/o. This suggests that the amorphous phase may be present in deposits containing a little as 5 a/o W. Alloys containing 3 a/o W were dense and compact and displayed a chloride pitting potential of + 0.3 V versus unalloyed Al. Heat treatment was explored as a method to address the powdery morphology of those deposits with a high W content, but XRD analysis indicated that this approach leads to the precipitation of at least one new phase (Al5W) and a decrease in the chloride pitting potential.

Citation

Journal of the Electrochemical Society

Volume

161

Issue

9

Pub Type

Journals

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DOI Link

Citation

Tsuda, T. , Ikeda, Y. , Arimura, T. , Hirogaki, M. , Imanishi, A. , Kuwabata, S. , Stafford, G. and Hussey, C. (2014), Electrodeposition of Al-W Alloys in the Lewis Acidic Aluminum Chloride-1-Ethyl-3-Methylimidazolium Chloride Ionic Liquid, Journal of the Electrochemical Society, [online], https://doi.org/10.1149/2.016409jes (Accessed December 3, 2024)