Effect of Cu and Nb additions on crystallization kinetics of Fe80P13C7 bulk metallic glasses

The crystallization kinetics of Fe80−x−yP13C7CuxNby (x, y = 0, 0.6 at.%) bulk metallic glasses (BMGs) for the first crystallization peak is investigated to understand the crystallization mechanism. The effects of a minor Cu and Nb addition on the glass forming ability (GFA), thermal stability, apparent activation energy and crystallization kinetics of Fe80P13C7 BMG have been studied. Nb addition can enhance the GFA and thermal stability but it is opposite to Cu addition. The apparent activation energy decreases with Cu addition but increases with Nb addition. The local Avrami exponent indicates the primary crystalline phase without Cu addition, i.e. Fe3(P,C), is a low-dimensional growth of pre-existing nuclei. With Cu addition, the primary crystalline phase is α-Fe, which is a high-dimensional growth with an increasing nucleation rate. Nb addition suppresses the growth rate of the primary precipitated phase, resulting in a higher-dimensional growth.