Mechanically Milled Nanostructured Fe1−xAlx Alloys: Magnetic Study

The study has been made on the identification of the changes in the magnetic behavior of Fe1-xAlx (x = 0.3, 0.4, 0.5, 0.6) powders during mechanical alloying (MA). The ball milling process leads to formation of solid state reaction assisted by severe plastic deformation due to which crystallite size reduced and as a result of which interesting magnetic properties are developed. The evolution of magnetic order in high-energy ball-milled Fe-Al solid solution has been investigated using Fe-57 Mossbauer spectroscopy and vibrating sample magnetometer (VSM). Mossbauer spectra and the hyperfine field distributions (HFD) of all the samples show the presence of both magnetic and paramagnetic components in the samples. The corresponding bulk magnetization studies also show that the Al rich samples are also ferromagnetic that can be attributed to the presence of disordered Fe rich phases due to non-equilibrium process of alloying. In Fe-rich samples, the formation of an off stoichiometric Fe3Al phase is favored while in case of Al-rich samples both Al-rich phases and clustering of Fe and Al atoms are present. The systematic variation in the magnetic properties has been qualitatively correlated with the evolution of microstructure, reduction in grain size (obtained using transmission electron microscopy) and enhanced inter granular exchange coupling.