New criteria for predicting compositions with high glass-forming ability in Zr–Co–Al alloys

Abstract

We show that the widespread parameters PHS, PHSS and δ related with mixing enthalpy, mismatch entropy, configurational entropy and atom size difference do not provide proper prediction of the bulk metal glasses (BMGs) compositions with high glass-forming ability in Zr-Co-Al system. A new computational approach has been developed for the accurate determination of BMGs compositions having a maximum critical diameter (Dmax). Using new parameters ΘCo-Zr(xCo), ΘAl-Zr(xAl), the range of Co-Zr-Al compositions with the best GFA was determined and Zr55Co29Al16 composition with maximum Dmax was identified. The thermodynamic mixing functions (∆Gmix, ∆Hmix) for the glass-forming Zr-Co-Al system were calculated for the first time. The results obtained reveal a relationship between thermodynamic and geometric factors and open up prospects for the development of reliable theoretical methods for new metallic glasses discovery.