Exceptional Oxidation Resistance of High-Entropy Carbides up to 3600 °C.

Abstract

Achieving exceptional oxidation resistance at elevated temperatures is long desirable for ultrahigh-temperature materials to be used in relevant applications such as hypersonic flights, re-entry vehicles, and propulsion systems. However, their practical service temperatures are typically limited to below 3000 °C. Here, the exploration of (Hf, Ta, Zr, W)C high-entropy carbides with exceptional oxidation resistance of 2.7 µm·s^-1 up to 3600 °C through a high-entropy compositional engineering strategy is reported. This impressive oxidation behavior arises from the formation of unique dual-structural oxide layers involving numerous high-melting-point W particles uniformly embedded within molten (Hf, Me)₆(Ta, Me)₂O₁₇ (Me = metal element, Hf, Ta, Zr, and W) primary oxides. The developed (Hf, Ta, Zr, W)C demonstrates a significant breakthrough for ultrahigh-temperature applications up to 3600 °C, paving the way for further design of advanced ultrahigh-temperature materials capable of serving at higher service temperatures.