A study of the effects of surface crystallization on the properties of metglas 2605 CO (Fe67Co18B14Si1).

Samples of Metglas 2605 CO have been investigated with X-ray diffractometry and transmission electron microscopy. The studies show the existence of a crystalline layer on the wheelside of the as-quenched ribbon although the degree of crystallization varies between batches. The microscope reveals different forms of crystallization products (e.g. dendrites and spherulites) as well as different phases including α-iron, β-cobalt and Co3B. The Crystallization kinetics also vary between batches but do not appear to be influenced by the surface layer. On the other hand the DC coercivity of as-quenched ribbons is definitely influenced by the surface crystalline layer. Evidence for domain wall interaction with surface grains suggests that a pinning mechanism could be partly responsible for the elevated coercivity.