Electrochemical deposition of Galfenol

Abstract

This paper presents the results of the electrochemical deposition of Galfenol, an iron-gallium alloy, obtained from a Hull cell apparatus. In a Hull cell, the cathode is set at a pre-determined angle with respect to the anode electrode, which enables a wide range of current densities to be evaluated across a single sample. Copper clad substrates were electroplated using an aqueous based solution containing iron sulphate and gallium sulphate containing an insoluble platinum anode. Sodium citrate was used as a complexing agent to inhibit the formation of Fe(OH)3 within the plated film. Energy Dispersive X-Ray spectroscopy was carried out to determine the Fe and Ga percentages within the deposits. A proportion of 20% Ga and 80% Fe has been shown to give the maximum magnetostrictive response for Galfenol and this material percentage was achieved in this study. Current density and bath formulation were found to play a crucial role in deposit composition. High current areas yielded higher levels of Gallium within the deposits. X-ray Diffraction measurements determined that the deposited crystalline structure of the deposit contains BCC Fe phases within the 20% Ga composition plated film. However these results contradict the published phase diagrams and resultant Energy Dispersive X-Ray Spectroscopy results.