Hindawi Publishing Corporation Journal of Nanomaterials Volume 2011, Article ID 519274, 8 pages doi:10.1155/2011/519274 Research Article Electrodeposition and Characterization of Nanocrystalline Ni-Fe Alloys R. Abdel-Karim, 1 Y. Reda, 1 M. Muhammed, 2 S. El-Raghy, 1 M. Shoeib, 3 and H. Ahmed 1 1 Department of Metallurgy, Faculty of Engineering, Cairo University, Giza 12613, Egypt 2 Functional Materials Division, Royal Institute of Technology, 16440, Stockholm, Sweden 3 Metals Technology Department, Central Metallurgical Research & Development Institute (CMRDI), El-Tebbin, Helwan 11421, Egypt Correspondence should be addressed to R. Abdel-Karim, randaabdelkarim@gmail.com Received 20 November 2010; Accepted 19 January 2011 Academic Editor: Donglu Shi Copyright © 2011 R. Abdel-Karim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Nanocrystalline Ni-Fe deposits with different composition and grain sizes were fabricated by electrodeposition. Deposits with iron contents in the range from 7 to 31% were obtained by changing the Ni 2+ /Fe 2+ mass ratio in the electrolyte. The deposits were found to be nanocrystalline with average grain size in the range 20–30 nm. The surface morphology was found to be dependent on Ni 2+ /Fe 2+ mass ratio as well as electroplating time. The grains size decreased with increasing the iron content, especially in case of short time electroplating. Increasing the electroplating time had no significant effect on grain size. The microhardness of the mate- rials followed the regular Hall-Petch relationship with a maximum value (762 Hv) when applying Ni 2+ /Fe 2+ mass ratio equal to 9.8. 1. Introduction Ni-Fe alloys ranging in composition from Ni-rich Premalloy to the iron-rich Invar have variety of high technology applications due to their wide spectrum of properties. Due to their unique low coefficient of thermal expansion (CTE) and soft magnetic properties, nickel-iron alloys have been used in industrial applications for over 100 years. Typical examples of applications that are based on the low CTE of Ni-Fe alloys include thermostatic bimetals, glass sealing, integrated circuit packing, cathode ray tube shadow masks, and composites molds/tooling and membranes for liquid natural gas tankers. Applications based on soft magnetic properties include read-write heads for magnetic storage, magnetic actuators, magnetic shielding, and high- performance transformer cores [1]. Ni-Fe systems are fabricated in the form of alloys, multilayers, and nanowires using different techniques such as vacuum evaporation, cold rolling, single-roll rapid quench- ing, and sputtering electrodeposition [2, 3]. Among several methods, electrodeposition is an advan- tageous method for producing Ni-Fe alloys due to flexibility, low cost, and capability of being used for parts with any size and geometry [4]. Electrolytic growth of metals differs from other methods as it provides the possibility of depositing films with structures different from those formed from vapor phase. Also the electrodeposition technique allows the deposition under normal conditions of temperature and pressure and requires relatively inexpensive equipment [5]. The electrodeposition of Ni-Fe alloys has been studied by several researchers [6–10], and it has been shown that the composition and the grain size of the deposits can be varied by controlling the deposition parameters as well as the electrolyte composition. The magnetic, mechanical, and corrosion properties of Ni-Fe electrodeposits are affected by a number of factors including roughness, grain size, and alloy composition. In turn, these parameters are affected by processing variables such as plating bath chemistry, pH, and temperature as well as the applied current density and electrolyte mixing conditions at the cathode surface [4]. While bath chemistry, pH, and temperature can usually be controlled, significant variations in current density and electrolyte mixing often occur during plating, leading to nonuniformities in deposit composition [11].