NANOCRYSTALLINE FORMATION IN AMORPHOUS Fe79B16Si5 AND Fe78B13Si9 RIBBONS

Abstract

Nanocrystalline formation in the amorphous ribbons, Fe 79 B 16 Si 5 and Fe 78 B 13 Si 9, resulting from annealing the ribbons at temperatures below their crystalline temperature is followed by Mossbauer spectroscopy. It is seen that in the B-rich Fe 78 B 16 Si 5 ribbons, the crystallization is a two stage process: amorphous →α-Fe(Si) nanocrystalline formation → (α-Fe, Fe 2 B ) nanocrystalline formation while the crystallization in the B-poor Fe 78 B 13 Si 9 ribbons is a three stage process: amorphous → Fe 3 B nanocrystalline formation → α-Fe(Si) nanocrystalline formation → (α-Fe, Fe 2 B ) nanocrystalline formation. These direct observation confirms the inferred formation of nanocrystallites obtained from magnetization measurements of similar type Fe-Si-B amorphous alloys. Our study also indicated that the α-Fe(Si) nanocrystallites survives at the higher temperatures.