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

Abstract

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 δ = T x /( T l − T g) (where T g, T x and T l 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 γ (= T x /( T l + T g)) and T rg (= T g/ T l) in reflecting the GFA, which implies that the δ criterion has a much better interrelationship with GFA than γ and T rg. It is also demonstrated that the δ 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.