The phase diagram and strengthening behavior of compositionally complex carbides under high pressure

Abstract The application of compositionally complex carbides under extreme conditions has garnered significant attention. The phase diagram compositionally complex transition metal carbide (Ta 0.2 Nb 0.2 Hf 0.2 Zr 0.2 V 0.2 )C for synthesis under high‐pressure and high‐temperature has been systematically investigated for the first time, and a pressure‐induced decrease in the compositionally complex carbides phase formation temperature was observed. The asymptotic Vickers hardness and bulk modulus of (Ta 0.2 Nb 0.2 Hf 0.2 Zr 0.2 V 0.2 )C reached 24.0 GPa and 311.3 GPa. The bulk modulus demonstrates an approximate 30% improvement compared to the average values of individual carbides, indicating that it possesses relatively competitive mechanical properties within the compositionally complex carbides group. The Claperon equation has been utilized to predict the lattice contraction of compositionally complex carbides during phase formation, and the physical mechanism of the high‐pressure strengthening has been proposed accordingly. In summary, the research of pressure–temperature phase diagram and the high‐pressure strengthening mechanism lay a valuable theoretical basis for the structural design and performance optimization of novel compositionally complex carbides.