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

Developing environmental barrier coating (EBC) materials with superior CMAS corrosion resistance represents a current research priority in rare-earth silicates. Previous studies have demonstrated that multicomponent rare-earth design can significantly enhance CMAS resistance performance, driven by differential rare-earth behavior during the corrosion process. This study investigates RE element synergy mechanisms 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 evolution of reactants and products. Results reveal that performance divergence in corrosion primarily stems from a mechanistic transition, from dissolution-reprecipitation to intergranular penetration, dictated by rare-earth ionic characteristics (mainly the cation radius). Comparative analysis confirms that an optimal active/inert stoichiometric ratio could simultaneously stimulate the precipitation-induced corrosion mitigation and the intrinsic resistance enhancement, establishing a design framework for multicomponent rare-earth disilicates for anti-CMAS EBC applications.