Direct evidence of two different relaxation processes induced by heat treatment on Fe40Ni40B20glassy ribbons

Abstract

The effect of heat treatment on Fe₄₀Ni₄₀B₂₀ glassy ribbons (V0040) has been studied by differential scanning calorimetry, X-ray diffraction, TEM and Mossbauer spectroscopy. Mossbauer data were fitted considering the asymmetry of the lines using an appropriate model (that of Brand et al.). Calorimetrically there are two effects, one exothermic and the other endothermic, that can be separated by selective heat treatments of the samples. X-ray diffraction, TEM and Mossbauer spectroscopy do not show any evidence of crystallisation or phase separation. Heat treatments induce changes in long-range order parameters but there is no such evidence on short-range order parameters. The analysis of the set of results provides direct evidence of the existence of two different relaxation mechanisms induced by heat treatment. One of them forces the local magnetisation to be more aligned with the ribbon plane than in the as-quenched glass, while the other randomises it.