Evaluation of glass-forming ability for bulk metallic glasses based on characteristic temperatures

A new criterion omega(2), defined as T(g)/(2T(x)-T(g))-T(g)/T(1) (wherein T(g) is the glass transition temperature, T(x) the onset crystallization temperature, and T(1) the liquidus temperature), has been proposed to assess the glass-forming ability (GFA) of bulk metallic glasses (BMGs) based on the classical crystallization theory and the crystallization resistance. The analysis indicates that the factors T(g)/(2T(x)-T(g)) and T(g)/T(1) could reflect the crystallization resistance and liquid phase stability of metallic glasses, respectively. From the available experimental data in literatures, the new criterion omega(2) has a better correlation with the GFA of metallic glasses than all other existing criteria such as T(rg)(=T(g)/T(1)), Delta T(x)(=T(x)-T(g)), gamma(=T(x)/(T(g)+T(1))), Delta T(rg)(=(T(x)-T(g))/(T(1)-T(g))) alpha(=T(x)/T(1)), beta(=T(x)/T(g)+T(g)/T(1)), delta(=T(x)/(T(1)-T(g))), phi(=T(rg)(Delta T(x)/T(g))(0.143)), gamma(m)(=(2T(x)-T(g))/T(1)), beta(=T(x)xT(g)/(T(1)-T(x))(2)) and xi(=Delta T(x)/T(x)+T(g)/T(1)). It has also been demonstrated that this omega(2) parameter is a simple and efficient guideline for exploring new BMG formers. (C) 2009 Elsevier B.V. All rights reserved.