Identification of bulk metallic forming compositions through thermodynamic and topological models

Abstract

This paper attempts to optimize the bulk metallic glass forming compositions using enthalpy of chemical mixing (DHchem) as thermodynamic, mismatch entropy (DSs/kB) as topological and configurational entropy (DSconfig/R) as statistical parameters. The product of DHchem and DSs/kB which is termed as PHS in the DSconfig/R range of 0.9 to 1.0 can be correlated strongly to glass forming ability. PHS being an important parameter has been used to design the quaternary and quinary Bulk Metallic Glass compositions from ternary compositions. This has been demonstrated for two Zr rich quaternary systems in Zr-Ti-Cu-Ni and Zr-Cu-Ni-Al based bulk metallic glasses. By weighing approach of PHS of four Zr rich quaternary systems and one non-Zr rich systems a new Zr rich quinary bulk metallic glass in Zr-Ti-Cu-Ni-Al system is designed. Mechanical alloying is used to prepare the bulk amorphous powder at the compositions predicted by the model in order to validate the model.