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The available glass forming ability criteria have been examined by classifying them into four basic categories depending on critical temperatures, thermodynamic quantities, topological and kinetic aspects of glass forming alloys. A large number of glass forming alloys of widely varying natures and origin have been analysed with their experimentally measured properties to assess their glass forming ability. A novel approach using kinetic viscosity of glass forming alloys obtained by the Vogel–Fulcher–Tamman equation and the critical cooling rate calculated from the TTT diagram is demonstrated as an excellent universal glass forming ability criterion. Moreover, thermodynamic and topological modelling results through computation of a novel PHSS parameter for various alloy compositions spanning different alloy systems have rendered qualitative guidelines on propensity for glass formation in multicomponent alloy systems. Besides, the importance of kinetic interpretation of PHSS range observed for glass forming alloys is also elaborated.

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In the present investigation, thermodynamic and topological concepts have been used together to understand the formation of bulk metallic glasses. The article attempts to develop a parameter that combines chemical mixing enthalpy (DH chem ), mismatch entropy normalized by Boltzmann constant (DS r /k B ), and configurational entropy (DS config /R), which can be effectively used to identify the best bulk glass forming compositions in multicomponent systems. The DH chem for multicomponent systems has been calculated by extending the MiedemaÕs macroscopic model, and DS r /k B was obtained from MansooriÕs approach. The iso-DH chem , iso-DS r /k B , and iso-DS config /R contours have been developed. The product of DH chem and DS r /k B in the DS config /R range of 0.9 to 1.0 can be correlated strongly to glass forming ability. This has been demonstrated in the case of the quaternary Cu-Zr-Ti-Ni bulk glass forming system to determine the bulk metallic glass forming compositions. Mechanical alloying is used to prepare the bulk amorphous powder at the compositions predicted by the model in order to validate the model.

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