Synthesis and characterization of electrodeposited nanocrystalline nickel-iron alloys

Nickel-iron nanocrystalline alloys with different compositions and grain sizes were fabricated by electrodeposition. The iron content of the deposits was changed by varying the Ni/Fe ion ratio in the electrolyte. X-ray diffraction (XRD) analysis was applied for measuring the lattice parameter, grain size and the level of internal strain of the deposits. The strength of the alloys was evaluated by microhardness testing. The results of this study revealed that at a constant grain size of approximately 11 nm the hardness depends strongly on the iron content. The hardness showed a maximum around 20% Fe. The grain size of the alloys with 4-6% iron was very sensitive to the deposition conditions. The hardness of these alloys followed the Hall-Petch relationship. The alloys with equal or more than 35% Fe cracked upon deposition. The tendency to cracking was correlated with the level of internal stresses in the deposits. (C) 2002 Elsevier Science B.V. All rights reserved.