Electrodeposited Iron Group Thin-Film Alloys: Structure-Property Relationships

Abstract

Various iron group alloys have been electrodeposited and evaluated for properties including corrosion resistance, microstructure, electrical resistivity, magnetoresistance and other magnetic properties. Corrosion resistance depends on deposit composition and microstructure, which are controlled by solution composition and deposition variables. Maximum corrosion resistance was observed for 50Ni50Fe and 70Co30Ni binary alloys. The corrosion resistance of electrodeposited CoFe films was an order of magnitude lower than CoNi and NiFe films. Substantially increased corrosion resistance was obtained by adding Ni to CoFe alloys. However, addition of B only slightly increased corrosion resistance. For electrodeposited NiFe and CoNi thin film alloys, three distinct structural regions were observed: for NiFe alloys, fcc, mixed fcc and bcc, and bcc phases as deposit Fe content increased; for CoNi alloys, fcc, mixed fcc and hcp, and hcp as deposit Co content increased. The smallest grain size was obtained in the mixed phase region of both NiFe and CoNi alloys. For CoFe alloys, a mixed phase region was not observed; only fcc and bcc phases were obtained. Electrodeposited NiFe films from sulfate baths show superior soft magnetic properties including both lower coercivity and higher squareness than from chloride baths. Magnetic saturation of electrodeposited NiFe films follow bulk alloys where magnetic saturation increased with increased deposit Fe content. © 2001 The Electrochemical Society. All rights reserved.