On the Unavailability of Universal Glass Forming Ability Criterion

The present work examines different glass forming ability criteria (GFA), which distribute into four major categories based on different theories for glassy alloys. Four major categories are based on (i) characteristics transformation temperatures, (ii) Miedema approach, (iii) internal atomic configuration, and (iv) kinetic constraints (viscosity, diffusivity, etc.). Twelve alloys of widely different origin and nature (with respect to number of constituent elements, base element, critical casting thickness, etc.) have been selected for studying the applicability of different GFA criteria of different categories. The experimentally determined critical casting thickness (Z_max) of each alloy has been taken to be the measure of GFA. The best criterion of each category has been identified. Finally, it has been observed that no single criterion of any category alone shows satisfactory correlation with Z_max. However, two criteria of two different categories do not simultaneously fail. It has been concluded that to determine GFA of any random glass forming material, two different criteria of two different categories should be checked. If both results do not indicate similarity in them, GFA must be checked with third criteria of third category.