• • Non-equimolar (Zr0.2Ti0.2Ta0.3Cr0.3)C achieves superior oxidation resistance up to 2500 °C, with a dense oxide layer that suppresses mass gain and spallation, outperforming equimolar compositions.
• • Laser-assisted screening at 2500 °C identified Cr as the critical element; tuning Cr ratio from 0.25 to 0.3 in the equimolar base (Zr0.25Ti0.25Ta0.25Cr0.25)C led to optimal performance, demonstrating the importance of compositional engineering.
• • The protective oxide scale consists of molten (Cr, Me)(Ta, Me)O4 and (Ta, Me)2O5 phases embedded with (Zr, Me)O2 crystals, which seal defects and enhance thermal stability, providing a mechanistic basis for superior oxidation resistance.
• • The self-developed laser oxidation platform enables rapid, high-throughput screening of HEC compositions at 2500 °C, accelerating the discovery of oxidation-resistant materials for ultrahigh-temperature applications.