Insight into the synergistic effect of rare-earth elements on the CMAS corrosion behavior in (RE _1/4 Tm _1/4 Yb _1/4 Lu _1/4 ) ₂ Si ₂ O ₇ (RE = Gd, Ho, and Sc) materials at 1300 °C

Abstract Developing environmental barrier coating (EBC) materials with superior calcium–magnesium–aluminosilicate (CMAS) corrosion resistance represents a current research priority in rare-earth (RE) silicates. Previous studies have demonstrated that a multicomponent rare-earth design can significantly enhance CMAS resistance, driven by the distinct behaviors of rare-earth elements during the corrosion process. This study investigates the synergistic mechanisms of the RE element in disilicates. We designed three multicomponent (RE1/4Tm1/4Yb1/4Lu1/4)2Si2O7 (RE = Gd, Ho, and Sc) materials and subjected them to CMAS corrosion at 1300 °C for durations of 1, 4, and 50 h to elucidate the synergistic mechanisms of multicomponent rare-earth elements on CMAS corrosion. We systematically analyzed the role of rare-earth cations in CMAS corrosion by examining their influence on the evolution of reactants and products. The results reveal that performance divergence in corrosion primarily stems from a mechanistic transition from dissolution–reprecipitation to intergranular penetration, governed by rare-earth ionic characteristics (mainly the cation radius). Comparative analysis confirms that an optimal active/inert stoichiometric ratio could simultaneously promote precipitation-induced corrosion mitigation and intrinsic resistance enhancement, establishing a design framework for multicomponent rare-earth disilicates in anti-CMAS EBC applications.