Laser-assisted compositional engineering of high-entropy carbides with superior oxidation resistance at 2500 °C
High-entropy carbides (HECs) are promising candidates for ultrahigh-temperature applications, but their oxidation resistance at temperatures above 2000 °C remains a critical bottleneck. Here, we report a laser-assisted compositional engineering strategy to develop non-equimolar (Zr0.2Ti0.2Ta0.3Cr0.3)C HECs with superior oxidation resistance up to 2500 °C. Using a self-developed laser oxidation platform, we first screened equimolar (Zr0.25Ti0.25Ta0.25Me0.25)C (Me = Hf, W, Nb, Cr, V, Mo) samples at 2500 °C, identifying Cr as a critical element for forming protective oxide scales. Systematic tuning of Cr content revealed that the optimal composition (Zr0.2Ti0.2Ta0.3Cr0.3)C exhibits a dense, crack-free oxide layer composed of molten (Cr, Me)(Ta, Me)O4 and (Ta, Me)2O5 phases embedded with (Zr, Me)O2 crystals, which effectively seal defects and suppress oxygen diffusion. The synergistic effects of these phases lead to a significant reduction in mass gain and oxide layer thickness compared to equimolar counterparts. This work provides a new pathway for designing HECs with long-life oxidation resistance at 2500 °C, enabling their use in extreme environments such as hypersonic vehicle leading edges and rocket nozzle throats.