The role of entropy and enthalpy in high entropy carbides

The thermodynamic stability of equiatomic mixed carbides, commonly referred to as high entropy carbides (HECs), is investigated via the CALculation PHAse Diagrams (CALPHAD) approach for consisting group IVB and VB transition metal well tungsten carbide. Gibbs free energy B1-structured computed using compound formalism while that Bh-structured evaluated a point-defect model. required data CALPHAD are obtained from density functional theory calculations Debye-Grüneisen lower temperature limit at which HECs mix in equilibrium determined numerical analytical approaches. We find enthalpy mixing least important configurational these carbide compounds. where an solid solution present largely independent number components with only exception being solutions containing carbide, weak dependence noted. Furthermore, thermodynamically stable below approximately 1000 K those stabilized by alone, indicating many currently fabricated not room temperature. Collectively, our results demonstrate formation controlled competition between enthalpy, or thus materials should be multi-principal component since former terminology can misleading.