Enhanced CMAS resistance of (La0.25Sm0.25Gd0.25Ho0.25)AlO3 ceramic at 1300°C: Composition-driven regulation of reaction thermodynamics and kinetics

Exploring new materials with exceptional calcium-magnesium-alumina-silicates (CMAS) corrosion resistance is a pivotal research hotspot in advancing protective coatings for gas turbine engines. In this work, the CMAS corrosion behaviour and degradation mechanism of a newly developed high-entropy (La 0.25 Sm 0.25 Gd 0.25 Ho 0.25 )AlO 3 ceramic were systematically investigated at 1300°C with exposure durations of 4, 25, 50, and 100 h. The unique combination of multiple rare earth and Al compositions in (La 0.25 Sm 0.25 Gd 0.25 Ho 0.25 )AlO 3 ceramic enables simultaneous regulation of both the thermodynamic and kinetic aspects of the corrosion process: a low apatite formation threshold (governed by thermodynamics) and accelerated crystallization of reaction products (governed by kinetics). These factors collectively accelerate the reduction of CMAS corrosion reactivity and the formation of dense protective product layers. Consequently, after 100 h of CMAS exposure, the reaction layer thickness is effectively limited to only 66.4±10.2 μm, smaller than that of single-RE-principle REAlO 3 . This study reveals that (La 0.25 Sm 0.25 Gd 0.25 Ho 0.25 )AlO 3 represents a highly promising candidate for protective coatings applications, while simultaneously highlighting a composition design strategy for developing advanced anti-CMAS materials.