On the heating rate dependence of crystallization temperatures of metallic glasses

It is well known that the crystallization temperatures of metallic glasses show strong dependence on the heating rate. The right relationship between the crystallization temperatures and the heating rate are very important in illustrating crystallization behavior and in evaluating thermal stability of the metallic glasses. Up to now, the dependence is usually illustrated using Kissinger equation, Ozawa equation, Augis-Bennett equation, Lasocka equation, and Vogel-Fulcher-Tammann (VFT) nonlinear equation. The paper aims to exam the relationship between the crystallization temperature and the heating rates for several metallic glasses, mainly rare earth-based and Zr-based metallic glasses. The validity of the relationship has been evaluated using additional experimental data at even lower or/and higher heating rates as well as the continuous heating transformation diagrams for the metallic glasses. The difference of the five equations has been compared in the paper. Among the five equations, the Kissinger, Ozawa, and Augis-Bennett equations show similar trends for the studied metallic glasses. The VFT equation is considered as a better model to describe the heating rate dependence of the crystallization temperature for the metallic glasses investigated. (C) 2010 American Institute of Physics. [doi:10.1063/1.3457336]