Formation of nanocrystalline Fe–Ni alloys powders by mechanical alloying method

Abstract

Alloys of Fe–Ni with starting compositions of 50 and 65 at.% Ni have been prepared by mechanical alloying. Samples were milled in a SPEX Model 8000 mill with a ball to sample weight ratio of about 6:1. Phase formation as a function of milling time has been investigated for 8 and 12 h of milling times, which produce fully alloyed samples of Fe50Ni50 and Fe64Ni36, respectively. Alloys have been studied by X-ray diffraction and scanning electron microscopy. Structural changes of a disordered fcc phase (γ-FeNi) have been investigated by Rietveld’s analysis of X-ray powder diffraction data. The structural parameters, lattice parameter, phase fractions, mean crystallite size and strain of γ-FeNi phase were obtained from Rietveld analyses of the X-ray patterns. Powder morphology and particle size have been examined by the SEM. The chemical compositions of the samples were analysed by energy dispersive X-ray (EDX) spectroscopy.