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

A new criterion ω2, defined as Tg/(2Tx−Tg)−Tg/Tl (wherein Tg is the glass transition temperature, Tx the onset crystallization temperature, and Tl 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 Tg/(2Tx−Tg) and Tg/Tl could reflect the crystallization resistance and liquid phase stability of metallic glasses, respectively. From the available experimental data in literatures, the new criterion ω2 has a better correlation with the GFA of metallic glasses than all other existing criteria such as Trg(=Tg/Tl), ΔTx(=Tx−Tg), γ(=Tx/(Tg+Tl)), ΔTrg(=(Tx −Tg)/(Tl −Tg)), α(=Tx/Tl), β(=Tx/Tg+Tg/Tl), δ(=Tx/(Tl −Tg)), φ(=Trg(ΔTx/Tg)0.143), γm(=(2Tx −Tg)/Tl), β(=Tx×Tg/(Tl −Tx)2) and ξ(=ΔTx/Tx+Tg/Tl). It has also been demonstrated that this ω2 parameter is a simple and efficient guideline for exploring new BMG formers.