Study of the Predictability of Properties and Phase Stability of High Entropy Carbides (HECs) from their respective Transition Metal Carbides (TMCs) Using First Principles Study

High Entropy Carbides (HECs) have been predicted using an entropy-forming-ability (EFA) descriptor using first principles to identify candidate compositions with phase stability. These predicted compositions were applied to disordered refractory carbides containing five metals, synthesized experimentally in a rocksalt structure, and their mechanical properties were measured. In this study, using Density Functional Theory calculations, we address two questions: (1) to what degree can the properties of HECs created by equi-molar combinations of five of the set of eight refractory metals Hf, Nb, Mo, Ta, Ti, V, W, and Zr be predicted from their respective binary Transition Metal Carbides (TMCs), and (2) can empirical relationships from properties of the TMCs be used to predict phase stability for these materials. For the former question, it is found that lattice constant, binding energy and bulk modulus are well approximated by TMCs averages, but carbon vacancy formation energies are less predictable. To address the second question, correlations are explored between TMCs properties and the entropy forming ability (EFA) of all 56 possible five-element combinations of the eight refractory elements. Our study of the predictability of HECs has been extended to explore the effects of lattice distortion through the introduction of vacancy and interstitial point defects. We anticipate that this comprehensive study will provide valuable insights into how point defects influence HEC properties and the predictability from their respective TMCs.