Microstructural and kinetic aspects of devitrification of Fe₄₀Ni₄₀B₂₀ metallic glass

Abstract

The crystallization characteristics of Vitrovac 0040 commercial glass with a composition of Fe₄₀Ni₄₀B₂₀ have been investigated in detail using differential scanning calorimetry, X-ray diffraction, optical and electron microscopy techniques. The results confirm the simultaneous occurrence of four kinds of crystalline precipitates with differing growth behaviour. The overall transformation kinetics of the eutectic product which had the highest growth rate has been documented. The result yielded a low value of 2.08 for the Avrami exponent, which has been attributed to its athermal nucleation and anisotropic growth behaviour. The diffusivity obtained from interlamellar spacings has been found to agree well with the previous values obtained by direct measurement using secondary ion mass spectroscopy for boron diffusion.