Prediction of Glass Forming Ability Using Thermodynamic Parameters

Formation of a glassy phase in metallic systems is controlled to large extent by the composition of the alloy. Alloying behavior can be qualitatively predicted from the knowledge of enthalpy of mixing and atomic size mismatch among elements involved in bonding. A more quantitative description of glass forming ability (GFA) can be obtained by using a parameter P-HS [= Delta H-C(Delta S-sigma/k(B))], where Delta H-C is the chemical enthalpy of mixing and Delta S-sigma/k(B) is entropy due to atomic size mismatch normalized by Boltzmann constant. Using this criterion, alloys with high GFA were identified in several ternary systems. However, P-HS parameter was found to be insufficient to predict GFA in multicomponent systems. Present analysis indicates that the incorporation of configurational entropy into P-HS parameter resulted in more quantitative description to explain higher GFA in multicomponent systems. This new GFA parameter is called P-HSS (= P-HS x Delta S-C/R), where Delta S-C/R is the configurational entropy normalized by universal gas constant. Using P-HS and P-HSS parameters, GFA predictions are done for Fe-Zr-B, Fe-Cr-Zr-B, Fe-Cr-Ni-Zr-B, Cu-Zr-Ag-Ti, Cu-Zr-Al-Y and Cu-Zr-Al-Be systems and an attempt has been made establish the suitability of this new GFA parameter to various quaternary and quinary alloy systems.