The role of the residual amorphous matrix in determining the temperature dependence of soft magnetic properties of nc alloys

Abstract

We report here a large (300–400 K) increase of the decoupling temperature ( T c am) with increasing crystalline fraction in Nanoperm-type alloys. This is in contrast to the Finemet-type alloys where T c am varies some tens of K only around the original as-cast amorphous T c when the amorphous precursor is annealed around the first crystallization peak. H c and M r/ M s, versus T measurements have been used to monitor the exchange decoupling of the nanosized particles, because these parameters are more sensitive to decoupling than M s and μ i, which show no characteristic change at the decoupling. This enhancement of T c am has been tentatively attributed to the increasing boron content of the residual amorphous matrix whereas the zirconium atoms agglomerate in the grain boundary region.