Influence of additive adsorption on properties of pulse deposited CoFeNi alloys

In this paper, we investigated the conditions at the electrochemical interface for additive adsorption during the pulse current deposition of a CoFeNi alloy. Depending on the magnitude of the pulse currents used, different potentials and the corresponding additive coverage of CoFeNi surface are established affecting the CoFeNi alloy composition, concentration of incorporated C, S, and O inclusions, crystal structure, magnetic properties, and the surface quality of the deposit. The maximum content of S, O, and C in the CoFeNi deposit is found for the pulse current where the electrode potential is in the range where the maximum additive coverage is observed, indicating a close correlation between additive adsorption and additive incorporation phenomena. The anomalous codeposition effect was moderate in the potential range where maximum surface coverage of additives occurs, causing the composition of the CoFeNi films and their crystal structure to have a relatively mild change for a broad range of pulse current densities. The surface quality and the coercivity of the CoFeNi alloy have a strong correlation to the additive coverage during the pulse stage, and practical aspects of these findings are discussed. (c) 2005 The Electrochemical Society. All rights reserved.