CMAS corrosion mechanisms governed by B-site chemistry in high-entropy rare-earth zirconates

The CMAS corrosion of high-entropy rare-earth zirconates involves complex reaction mechanisms that are sensitive to B-site chemistry, while the associated reaction pathways are not yet fully understood. This study investigates the CMAS corrosion behavior of (La 0.2 Nd 0.2 Gd 0.2 Ho 0.2 Y 0.2 ) 2 (Zr 1-x Ce x ) 2 O 7 ceramics with varying Ce doping levels (x = 0, 0.125, 0.25, i.e. 5RZ, 5RZC1, 5RZC2). The results indicate that rapid early-stage CMAS penetration in 5RZ is associated with insufficient reaction-layer continuity, whereas Ce-doped samples suppress early penetration by promoting a more continuous reaction layer; at longer durations, 5RZC1 enters a high-viscosity, low-mobility state leading to restricted reaction-layer growth with spinel formation, while 5RZC2 maintains partial melt fluidity and evolves toward coexisting spinel and anorthite. After 20 h of CMAS corrosion at 1300 °C, the reaction-layer thicknesses are approximately 140 μm (5RZ), 104 μm (5RZC1), and 131 μm (5RZC2), indicating the significant role of Ce incorporation in governing corrosion kinetics and final corrosion behavior. These observations indicate that Ce incorporation controls the CMAS–ceramic reaction and the structural and viscosity evolution of the residual melt, determining the corrosion end states and reaction-layer growth.