Mössbauer study on the coupling interaction of Fe-based nanocrystalline alloys

A two-phase system of Fe-based nanocrystalline alloys is here investigated. The nanocrystalline Fe69.5Cu0.5Cr4V5Si13B8 alloys, which consist of two magnetic phases: α-FeSi grains and an amorphous matrix, were prepared by annealing the amorphous ribbons. Mossbauer spectroscopy and magnetic measurements at elevated temperatures were carried out. The results show that the exchange coupling interaction exists between grains through the amorphous matrix, and obviously affect the soft magnetic properties of the nanocrystalline alloys. A phenomenological coupling model is applied to estimate the coupling intensity for samples annealed at different temperatures and the data can reasonably explain why the nanocrystalline alloys annealed at 540 °C hold the best soft magnetic properties.