Correlation between microstructure and magnetic properties in mechanically alloyed nanogranular Fe100 − xAlx

Structural and magnetic properties of Fe100 − xAlx powders, mechanically alloyed for a fixed time of 10 h, is presented. Although Mössbauer studies show that the magnetic phase is a minimum, bulk magnetic properties like area of the M-H loop and coercivity are maximum in the Al-rich x = 66 (Fe-66 at.% Al) system. Quadrupole splitting and isomer shift of the non-magnetic phase in this system are identical to that of stoichiometric FeAl2. The unexpected trend of the bulk magnetic parameters in the x = 66 composition is explained in terms of the enhanced intergranular exchange coupling, mediated by the Fe atoms in the non-magnetic phase.