A novel parameter to describe the glass-forming ability of alloys

In this paper, we propose a new parameter for glass-forming ability (GFA) based on the combination of thermodynamic (stability of stable and metastable liquids by ΔT_m=T_m^mix-T_l and ΔT_x=T_x-T_g, respectively) and kinetic (resistance to crystallization by T_x) aspects for glass formation. The parameter is defined as ε=(ΔT_m+ΔT_x+T_x)/T_m^mix without directly adding T_g while considering the whole temperature range for glass formation up to T_m^mix, which reflects the relative position of crystallization curve in continuous cooling transformation diagram. The relationship between the ε parameter and critical cooling rate (R_c) or maximum section thickness for glass formation (Z_max) clearly confirms that the ε parameter exhibits a better correlation with GFA than other commonly used GFA parameters, such as ΔT_x (=T_x-T_g), K (=[T_x-T_g]/[T_l-T_x]), ΔT∗(=(T_m^mix-T_l)/T_m^mix), T_rg (=T_g/T_l), and γ (=[T_x]/[T_l+T_g]). The relationship between the ε parameter and R_c or Z_max is also formulated and evaluated in the study. The results suggest that the ε parameter can effectively predict R_c and Z_max for various glass-forming alloys, which would permit more widespread uses of these paradigm-shifting materials in a variety of industries.