Structure and magnetic properties of Fe-rich nanostructured Fe100−XNiX powders obtained by mechanical alloying

Fe100_xNix alloys (x=22, 26, 30, 50 at%) were prepared by mechanical alloying (MA) of elemental powders in a high-energy planetary ball mill type Fritsch (Pulvérisette P7). Scanning electron microscopy (SEM), X-ray diffractometry and Mössbauer spectroscopy were used to study the mixing at nanometric scale. It is observed a gradual formation of mixture of phases as fcc (γ) and bcc (α) with a nanoscale grain size. In addition, as the average grain size is decreased with a progressive enlargement of peaks of X-ray diffraction. The Mössbauer Spectroscopy confirmed the ferromagnetic ordering and was used to calculate the distribution of hyperfine fields. Mössbauer spectra analysis has shown the presence of magnetic bcc-phase and paramagnetic phase □ (i.e. taenite), not detected by X-ray diffraction for Fe78Ni22 system.