Huge magnetic hardening ascribed to metastable crystallites during first stages of devitrification of amorphous FeSiBNbSn alloys

A huge magnetic hardening (i.e., increase of coercivity from 5 A/m up to 4. 4 kA/m) was reported for Fe75Si11B10Nb3Sn alloy ribbons during their very f irst stage of crystallization from an initial amorphous state. In contrast, Fe78Si11B10Sn1 showed no such hardening, while a moderate hardening was ob served for Fe76Si11B10Nb3. This outstanding change was ascribed to the gene ration of metastable nanocrystallites that disappear upon heating at higher temperatures. A noticeable softening was then recovered (with a decrease o f coercivity down to 0.8 kA/m) once the optimum homogeneous conventional na nocrystalline phase was achieved. Both structure and magnetic evolutions ar e followed by different techniques.