Reverse design of non-equimolar rare-earth monosilicates: Data-driven and molecular dynamics insights into CMAS corrosion mechanism

Rare-earth monosilicates (REMs) exhibit excellent resistance to calcium-magnesium-alumino-silicate (CMAS) corrosion, but the vast compositional space, particularly for non-equimolar ratios, poses significant challenges for rapid development and mechanistic understanding. In this work, a reverse design strategy was employed to tailor non-equimolar REMs, coupled with a multiscale investigation framework. Density functional theory trained neuroevolution potential molecular dynamics simulations, revealed the atomic-scale CMAS corrosion mechanism: initial interfacial contact, interdiffusion with bridging oxygen formation and substitution channel migration, and final apatite phase precipitation. Lattice distortion in the REMs mainly from RE cation sites and spatial reorientation of [SiO₄] tetrahedra. Data-driven models for residual melt viscosity and phase evolution demonstrated strong cross-scale consistency, identifying Sc-rich compositions as exhibiting superior corrosion resistance during the initial stages of CMAS attack at 1400 °C. This combined data-driven, simulation, and experimental workflow offers a robust pathway for building multiscale frameworks to alleviate CMAS degradation in environmental barrier coatings.