Effect of Ni on the lattice parameter and the magnetic hyperfine field in (Fe70Al30)100 − xNix alloys

Samples of the (Fe70Al30)100 − x Ni x system, with x = 5, 10, 15, and 20, were prepared by mechanical alloying using milling times of 12, 24, 36, 48, and 72 h and characterized by X-ray diffraction (XRD) and Mossbauer spectrometry (MS). XRD of all the samples allowed us to identify the BCC structure as the main component. A decreasing lattice parameter, as the milling time and Ni content increase, was obtained. The MS experiments were carried out at room temperature. The spectra were fitted with a hyperfine magnetic field distribution (HMFD). The Mean Hyperfine Fields (MHF) are ranged between 27 and 29 T with a small dependence with the milling time and was not strongly influenced by Ni content. An additional paramagnetic single line in the spectra of samples with x = 20 and that of sample with x = 15 and milled during 72 h must be included. The Mossbauer spectral area of this phase increases when the milling time increases and it was associated to an FCC phase.