Coercivity effects of iron microcrystals in amorphous Fe81B13.5Si3.5 C2

Abstract

Primary crystallization of the titled alloy (Metglas 2605SC) occurs as dendritic microcrystals of αFe, which have cause a large increase in coercivity. This paper reports transmission electron microscopy measurements of the average length and number density of iron crystals as a function of annealing. The dendrites initially lengthen isothermally at a constant rate governed by an activation energy of (230±20) kJ/mole. The coercivity increases linearly with mean crystallite dimension between 0.1 and 0.6 μm, and stronger than linearly above 0.6 μm.