Experimental studies on electrodeposition of CoFe alloys

Abstract

CoFe alloy films with composition in the range of 47 to 67 wt.% Fe were electroplated from a sulfate-based bath operated at pH 2.6-2.86 and current densities of 7-28 mA/cm2. CoFe films exhibited nodules at low current density and high pH but not at high current density and low pH. However, under the latter conditions pits were formed on the film surface. The pits were successfully eliminated by pulse plating. The CoFe films were plated up to a thickness of 3 microns without delamination. A CoFe alloy with a composition of 53 wt.% Fe was found to have a saturation magnetization of 2.18 Tesla, in contrast to the literature value of 2.4 Tesla for the cast alloy. The electroplated 2.0-2.1 Tesla CoFe films showed oxygen contents of up to 10 atomic percent. Incorporation of oxygen into the films during the plating process is believed to be the main cause for the lower magnetization of these plated films as compared to the cast alloys.