High-entropy engineering promotes the thermal properties and corrosion resistance of rare-earth hafnates

Rare-earth hafnates are gaining attention due to their excellent high-temperature phase stability and low thermal conductivity. However, they still have shortcomings of low thermal expansion and poor calcium-magnesium-aluminum-silicate (CMAS) corrosion resistance. In this study, we employed high-entropy engineering and component design to synthesize three high-entropy hafnates (La0.2Ce0.2Nd0.2Gd0.2T0.2)2Hf2O7 (T = Dy, Ho, Tm) as well as a single-component hafnate Nd2Hf2O7, with the aim of preparing thermal barrier coatings with an excellent comprehensive performance. Test results indicate that the high-entropy compositions have excellent thermal properties. The focus is on elucidating the corrosion process and failure mechanism of CMAS at 1300 degrees C. Moreover, the analysis of residual CMAS and corrosion products was conducted to evaluate the discrepancies in CMAS corrosion behavior among the various compositions.