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

Based on the consideration of both the resistance of amorphous phase against crystallization and the stability of under-cooled liquid against competing crystalline phase formation, a criterion ω, defined as T_g/T_x - 2T_g/(T_g + T_l) (T_g, T_x and T_l denote the glass transition temperature, the onset crystallization temperature and the liquidus temperature, respectively), has been proposed for evaluating the glass-forming ability (GFA) of bulk metallic glasses (BMGs). A survey of the readily available experimental data associated with the thermal analysis of various glass-forming alloys shows that the new criterion ω exhibits the best correlation with the maximum section thickness (D_max) as well as the critical cooling rate (R_c) for glass formation among other criteria proposed in recent years, such as T_rg(=T_g/T_l), ΔT_x(=T_x - T_g), γ(=T_x/(T_g + T_l)), γ_m(=(2T_x - T_g)/T_l), ΔT_rg(=(T_x - T_g)/(T_l - T_g)), δ(=T_x/(T_l - T_g), φ(=T_rg(ΔT_x/T_g)^0.143, α(=T_x/T_l), β(=(T_x/T_g + T_g/T_l) and β(=T_x × T_g/(T_l - T_x)²). Therefore, it can be anticipated that this new criterion will be used as a useful and efficient guideline for exploring new BMG formers.