First-principles study on the thermodynamic miscibility and mechanical properties of high-entropy quaternary metal nitrides

Recent advancements in high-entropy metal nitride (HEMN) ceramics have demonstrated their significant potential as innovative structural and functional materials . Utilizing first-principles calculations alongside mixing thermodynamic theory, we have investigated the thermodynamic miscibility and mechanical properties of three existing and twelve hypothetical quaternary HEMNs, incorporating nitrogen and four of the six Group IVB and VB refractory metals , Ti, Zr, Hf, V, Nb, and Ta. Calculations on mixing energy, mixing entropy, and lattice size difference confirm that all these fifteen HEMNs can be formed spontaneously at moderate temperatures. This finding therefore predicts twelve quaternary HEMNs, which can now be verified experimentally. In addition, our calculations reveal that all studied HEMNs exhibit a unique combination of high Vickers hardness , improved fracture toughness , commendable ductility, and an ultrahigh melting point. These characteristics underscore the potential of HEMNs in the development of materials suitable for ultra-high temperature applications and advance our understanding of high-entropy materials.