A new criterion for evaluating the glass-forming ability of bulk metallic glasses

A new criterion, derived according to the classical theory of nucleation and growth and the perspective of phase transformation kinetics, has been proposed for evaluating the glass-forming ability (GFA) of bulk metallic glasses (BMGs) by measuring the characteristic thermal parameters. A survey of the readily available experimental data associated with the thermal analysis of various BMG alloys show that the new criterion, defined as delta = T-x/(T-1 - T-g) (where T-g, T-x and T-1 denote the glass transition temperature, the onset of crystallization temperature and the liquidus temperature, respectively), is distinctly better than other currently used criteria, such as gamma (=T-x/(T-1 + T-g)) and T-rg (=T-g/T-1) in reflecting the GFA, which implies that the delta criterion has a much better interrelationship with GFA than gamma and T-rg. It is also demonstrated that the delta criterion has, exclusively, a strong ability to measure and predict the GFA of industrially important BMGs based on common metals, such as Cu and Fe. (c) 2006 Elsevier B.V. All rights reserved.