Abstract
Rare earth tantalates (RETaO(4)), known for their exceptional thermomechanical properties, are promising candidates for next-generation thermal barrier coatings (TBCs). However, the role of rare earth (RE) species in the CMAS (calcium-magnesium-aluminosilicate) corrosion behavior and mechanisms of RETaO(4) remains unclear, hindering their design and application as TBCs. This study employs a high-throughput approach to systematically investigate the CMAS corrosion mechanisms of RETaO(4) (RE = Nd, Sm, Eu, Gd, Dy, Ho, Y, and Er) at 1300 °C. Precise analysis of the microstructure and composition reveal that the primary corrosion products are (Ca(2-x)RE(x))(Ta(2-y-z)Mg(y)Al(z))O(7) solid solutions, along with minor amounts of Ca(2)RE(8)(SiO(4))(6)O(2) apatite. These corrosion products are observed both in the recession layer and at grain boundaries. The CMAS infiltration depth of RETaO(4) increases with the RE ionic radius. First-principles calculations indicate that the formation enthalpy of corrosion products becomes more exothermic as the RE ionic radius increases, promoting the formation of corrosion products. Additionally, the wetting behavior of liquid CMAS on RETaO(4) at high temperatures supports that RETaO(4) with smaller RE ionic radius present better corrosion resistance. These findings provide insights into the influence of RE species on the CMAS corrosion behavior of RETaO(4), offering guidelines for the rapid screening of CMAS-resistant TBC materials.