Understanding the CMAS corrosion behavior of high‐entropy (La _0.2 Sm _0.2 Er _0.2 Y _0.2 Yb _0.2 ) ₂ Ce ₂ O ₇

Abstract Ceramic thermal barrier coating (TBC) materials are used to protect the superalloys from the damage of harmful high‐temperature airflow and improve the efficiency of jet and gas turbine engines. However, the long‐term application of TBC materials and the robustness of these materials can be destroyed by aggressive calcium‐magnesium‐alumina‐silicate (CMAS) melt during high‐temperature service. Increasing the configuration entropy of material by doping multiple principal components has become a research hotspot in the design of corrosion‐resistant thermal barrier coating material and has opened an infinite space of chemical composition, structure, and material properties. In this study, high‐entropy (La 0.2 Sm 0.2 Er 0.2 Y 0.2 Yb 0.2 ) 2 Ce 2 O 7 was synthesized and its CMAS corrosion behavior was investigated by experimental investigation and first‐principles calculation. The effects of the increase of configurational entropy and the subsequent potential effects on the CMAS corrosion behavior of Ce‐based fluorite oxides have been sufficiently investigated. By compared with control samples, the high‐entropy (La 0.2 Sm 0.2 Er 0.2 Y 0.2 Yb 0.2 ) 2 Ce 2 O 7 possesses the minimum infiltration depth of CMAS melts and the denser corrosion reaction layer, indicating the best corrosion resistance. The corrosion resistance mechanism of high‐entropy (La 0.2 Sm 0.2 Er 0.2 Y 0.2 Yb 0.2 ) 2 Ce 2 O 7 was studied by first‐principles calculation. The greater stability and resistance to segregation of CMAS melt in the CMAS/(La 0.2 Sm 0.2 Er 0.2 Y 0.2 Yb 0.2 ) 2 Ce 2 O 7 system, the poor adsorption capacity for CMAS melt which leads to a weak infiltration ability of CMAS melt; the weakest interfacial chemical reaction at the interface indicated by the smallest value of Griffith rupture work and the least species migration of high‐entropy fluorite oxide can be responsible to the enhanced corrosion resistance. Our work reveals that increasing the configuration entropy can be an effective strategy for TBC material to enhance corrosion resistance.