Applied Surface Science 258 (2012) 6884–6890 Contents lists available at SciVerse ScienceDirect Applied Surface Science jou rn al h om epa g e: www.elsevier.com/locate/apsusc Magnetic property and corrosion resistance of electrodeposited nanocrystalline iron–nickel alloys G.P. Pavithra, A. Chitharanjan Hegde ∗ Electrochemistry Research Laboratory, Department of Chemistry, National Institute of Technology Karnataka, Srinivasnagar 575 025, India a r t i c l e i n f o Article history: Received 3 August 2011 Received in revised form 6 February 2012 Accepted 23 March 2012 Available online 30 March 2012 Keywords: Nanocrystalline Fe–Ni alloy deposition SEM XRD Magnetic property Corrosion behavior a b s t r a c t In the present investigation we have galvanostatically synthesized nanocrystalline Fe–Ni alloys on copper substrate. The effect of current density (c.d.) on composition, surface morphology and phase structure were studied for explaining the magnetic and electrochemical properties of the nanocrystalline alloy. The bath found to exhibit the preferential deposition of less noble Fe than Ni, and at no conditions of c.d., the deposition has changed from anomalous to normal type. Surface morphology and structural charac- teristics of the deposits were examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. As composition of the alloy varied, consequent to the current density a change of body centered cubic structure (bcc) to face centered cubic structure (fcc) was observed for nanocrystalline materials. Finally, the conditions responsible for peak magnetic property and corrosion resistance were optimized. Factors responsible for improved functional properties were explained in terms of surface morphology and crystalline grain size of the coatings. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Development of new materials; and understanding of phase structures and surface morphology is at the root of progress of material science. This is particularly true in the development of new magnetic materials for a variety of important applications. In this regard, process of co-deposition of iron–nickel (Fe–Ni) alloys by electrochemical reduction in aqueous solutions has long been a subject of scientific and technological interest with the earli- est studies dating back to the beginning of last century [1]. The solid state properties of these alloys which received considerable attention are their magnetic properties, and excellent corrosion resistance. They are used primarily as soft magnetic materials in the area of high-speed random-access computer memories [2]. This application region is dominated by perm-alloy type alloys, fre- quently with additional alloying elements. The relationships among the plating variables of Fe–Ni alloys are complicated by the nature of the co-deposition which is prevailing in mutual alloys of Fe- group metals. The binary alloys of iron group metals, namely Fe–Ni, Fe–Co and Ni–Co electrodeposition exhibits peculiar phenomenon of ‘anoma- lous co-deposition’. This term introduced by Brenner is being used to describe the preferential deposition of the less noble metal, Fe to the more noble metal, Ni [3]. In other words, the reduction of ∗ Corresponding author. Tel.: +91 9980360242; fax: +91 824 2474033. E-mail address: acrhegde@gmail.com (A.C. Hegde). Ni is inhibited while the deposition of iron is enhanced when com- pared to their individual deposition rates. Hence, electrodeposition of Fe–Ni alloys has attracted considerable attention due to their special characteristic nature and wide range of unique properties. Recently the phase structures of alloys have been analyzed by electrochemical techniques, such as galvanostatic and poten- tiostatic methods, and more often by anodic linear sweep voltammetry [4]. The literature pertaining to electrodeposition of mutual alloys of Fe group metals, namely Ni, Fe, Co and Zn, is rather exhaustive and many serious research works have been reported [4–8]. It has been identified that both face centered cubic (fcc) and body centered cubic (bcc) iron group metal alloy solid solutions have been produced by electrodeposition. These alloys were found to exhibit many useful properties such as high internal strength, hardness, high corrosion resistance and unusual magnetic prop- erties. Many magnetic alloys with different compositions were widely employed for various purposes. Ferromagnetic alloys, e.g., Fe–Co and Fe–Ni are few among many, and have received consider- able attention for their practical applicability in modern industries, such as in rockets, computers, space technology, etc. However, data on magnetic properties and corrosion resistance of electroplated Fe–Ni alloys are difficult to correlate as the wide variety of plat- ing baths and their operating conditions used, and it is difficult to distinguish between the factors that significantly affect them [9,10]. There exists a complex relation between plating variables, like bath composition and operating parameters, and deposit char- acters, such as magnetic and corrosion properties due to peculiar anomalous co-deposition. Therefore, it is hard to develop Fe–Ni 0169-4332/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.apsusc.2012.03.124