Diffusion of antimony in amorphous and crystallized Fe82B18

Diffusion coefficients D of antimony in the as-quenched amorphous Fe₈₂B₁₈ alloy were measured in the temperature range 575–640 K by Rutherford backscattering spectrometry. The measured values of D were found to lie in the range (4.6 × 10⁻²¹)−(4.4 × 10⁻¹⁹) m²s⁻¹ over the temperature range considered. An Arrhenius relation was fitted to antimony diffusivities, yielding values of 1.65 eV for the activation energy Q and 2.5 × 10⁻⁶m²s⁻¹ for the frequency factor D₀. In addition to the as-quenched samples, diffusion measurements were also carried out in relaxed (pre-annealed) and pre-crystallized specimens. The effect of relaxation treatment on D was found to be insignificant. The volume diffusion coefficients in the crystallized specimens were also found to be comparable with those in the amorphous specimens. This result is particularly striking since it is generally expected (based on extrapolation from high-temperature data) that diffusion in amorphous systems is several orders of magnitude faster than that in crystalline systems.