CRYSTALLIZATION BEHAVIOR OF FE78B13SI9, FE81B13SI3.5C2, FE66CO18B15SIAND FE77CR2B16SI5 METALLIC GLASSES

The crystallization behavior of alpha-Fe in Fe78B13Si9, Fe81B13Si3.5C2 , Fe66Co18B15Si and Fe77Cr2B16Si5 metallic glasses has been investigat ed under controlled crystallization conditions. Based on the onset tem perature for alpha-Fe crystallization, crystallite size and occupied v olume, it was concluded that nucleation is enhanced in the Go-bearing alloy; the G-bearing alloy exhibited an anomalous behavior while in th e Cr-bearing alloy the growth of the alpha-Fe crystallites is strongly inhibited. Nanocrystalline structures were restricted to sizes > 50 n m in the base-, C- and Co-bearing alloys, while crystallite sizes < 10 nm were obtained in the Gr-bearing alloy. By determining the rate of change of the number of nuclei with increasing annealing temperatures, the controlling mechanism, either nucleation enhancement and/or growt h inhibition, was clearly outlined.