The chemical and mono-phase stability of (TiCrZrVNb)C high entropy carbide ceramics (HECCs) were evaluated by the first‐principles calculations. The calculated negative formation energy of -39.98 kJ/mol and negative mixing Gibbs free energy above 1257 K indicated the chemical and mono-phase stability at high temperature, respectively. Moreover, the intrinsic toughness behavior was also evaluated by elastic constant calculation. Then, the HECCs films were successfully fabricated by multi-arc ion plating at specified deposition parameters. The experimental results showed that the HECCs films presented single rock‐salt crystal structure of nanocrystal grains and unique chemical fluctuations (CFs) from the atomic level to nanoscale. Owing to these unique features, the films not only exhibited high peak hardness of 32.57 ±0.98 Gpa, but also a satisfactory combination of superb yield strength of 9.5 Gpa and high toughness.

High entropy carbide ceramics,First-principles calculations,Mechanical properties,Chemical fluctuations,(TiCrZrVNb)C