Ultrafast synthesis of high-entropy carbides up to 3,273 K for superior oxidation resistance
Zihao Wen, Zhongyu Tang, Hong Meng, Lei Zhuang, Hulei Yu, Yanhui Chu
Abstract
Exploiting the huge compositional space is significant in achieving the superior oxidation resistance of high-entropy carbides (HECs) yet is challenging with conventional synthesis techniques. Herein, we develop an ultrafast high-temperature synthesis apparatus to reach a heating temperature of 3,273 K within seconds. Based on this apparatus, the equiatomic 4- to 9-cation HECs of the IVB, VB, and VIB groups with compositional uniformity are synthesized via carbothermal reduction. The oxidation resistance of all the as-synthesized HEC samples is then investigated via thermogravimetric analysis. The results show that the 6-cation HEC samples possess the best oxidation resistance. Their superior oxidation resistance is attributed to the formation of (Cr, Me)(Ta, Me)O4 and (Cr, Me)2O3 (Me = Hf, Zr, Ta, Nb, Ti, and Cr) protective layers, which are experimentally and theoretically proved to effectively inhibit the inward diffusion of oxygen. Such superior oxidation resistance enables potential applications in extreme environments.