Laser-assisted compositional engineering of high-entropy carbides with superior oxidation resistance at 2500 °C

Exploring high-entropy carbides (HECs) with superior oxidation resistance at 2500 °C is essential for their applications under ultrahigh-temperature environments. However, related studies have not yet been conducted. Here, we successfully explore non-equimolar (Zr0.2Ti0.2Ta0.3Cr0.3)C HECs with superior oxidation resistance up to 2500 °C through a laser-assisted compositional engineering strategy. Specifically, we first screen the compositions of a series of equimolar (Zr0.25Ti0.25Ta0.25Me0.25)C (HEC-Me, Me = Hf, W, Nb, Cr, V, and Mo) samples at 2500 °C via a self-developed laser oxidation platform, confirming the critical role of the Cr element. Further studies on the tuning of the Cr ratios in HECs reveal that the superior oxidation resistance in non-equimolar (Zr0.2Ti0.2Ta0.3Cr0.3)C HEC samples is primarily due to the synergistic effects of molten (Cr, Me)(Ta, Me)O4 and (Ta, Me)2O5 phases embedded by (Zr, Me)O2 crystals to effectively seal defects in oxide layers. This work provides a new path for developing HECs with superior oxidation resistance up to 2500 °C.