Magnetic properties and nanocrystallization of a Fe63.5Cr10Si13.5B9Cu1Nb3 alloy

Abstract Magnetic properties of a FINEMET-type alloy with partial substitution of Fe by Cr and their correlation with structural evolution upon annealing have been analyzed. Thermal stability of the amorphous alloy against nanocrystallization is enhanced with respect to the FINEMET composition and the Curie temperature of both, as-cast glassy alloy and amorphous matrix in nanocrystalline alloys, are lowered. For nanocrystalline samples measured at room temperature, a progressive increase in coercivity and a decrease in saturation magnetization with increasing crystalline fraction is observed. This could be ascribed to the low value of the T C of the amorphous matrix, close to room temperature, that make the nanocrystals be exchange-decoupled. Samples annealed for temperatures/times in the range of the second crystallization stage exhibit a strong magnetic hardening related to the formation of boride-type phases and recrystallization phenomena.