Structural Study of Amorphous FE₇₀M₁₀B₂₀ (M=CR, W, NB, ZR and HF) Alloys by X-ray Diffraction

Abstract

Local atomic structures in amorphous Fe₇₀M₁₀B₂₀ (M=Cr, W, Nb, Zr and Hf) alloys with different ΔT_x values were studied by the ordinary X-ray diffraction, anomalous X-ray scattering and EXAFS methods. Their local the atomic structures basically resemble each other, i.e. a random network structure of triangular prisms. Only difference in local atomic structure is a shape of the local structural unit. In the amorphous alloys containing M elements larger than Fe atoms, the prisms show distorted shapes due to a size difference Δr between M and Fe. A linear relation between Δr and ΔT_x, and a comparison of their crystallization processes suggest us that their thermal stability is attributed to difficulty in rearranging the irregular structural units because of a non-zero Δr value.