X-ray analysis and Rietveld refinement of ball milled Fe50Al35Ni15 powder

In this work, nanocrystalline Fe50Al35Ni15 powder was synthesized by mechanical alloying (MA) in a high-energy ball mill. The phase transformations and structural changes occurring in the studied material during MA, were investigated by X-ray diffraction. The end product of milling is a fine powder mixture consisting of a nanosized B2-FeAl(Ni) intermetallic phase and a disordered BCC alpha-Fe(Al,Ni) solid solution. The crystal size refinement was observed in all cases, while the lattice strain increases due to the severe plastic deformations and the structural defects. Transformation in the lattice parameters is principally dependent on the milling process and conditions. The diffusion of the Ni atoms was also investigated, and significant results were attained in the BCC phases. Indeed, the experimental results showed that an addition of 5% Ni retarded the formation of the intermetallic phase by 3 hours, with respect to our earlier studies.