Composition optimization of (Hf, Ta, Zr, Cr)C high-entropy carbides for good oxidation resistance

Oxidation resistance is crucial to the potential applications of high-entropy carbides (HECs) at elevated temperatures. Here, we realize the exploration of (Hf, Ta, Zr, Cr)C high-entropy carbides (HEC-TM, TM = Hf, Zr, Ta, and Cr) with good oxidation resistance by optimizing their compositions. To be specific, 21 kinds of HEC- x TM ( x = 0–25 mol%) samples are fabricated by a high-throughput ultrafast high-temperature sintering technique, followed by oxidation testing at 1673 K for 30 min. Among all the HEC samples, the as-fabricated HEC-0Zr samples are proved to possess the best oxidation resistance with an oxidation depth of only 53 µm. Further study on isothermal oxidation kinetics demonstrates that the as-fabricated HEC-0Zr samples follow a linear oxidation law. The good oxidation resistance of the as-fabricated HEC-0Zr samples is believed to result from the (Ta, Me) 2 O 5 phase with a low melting point, which can promote the densification of the oxide layer. This research opens up a new way for efficiently discovering new HECs for extreme applications.