Abstract
The ambiguous understanding of calcium-magnesium aluminosilicate (CMAS) corrosion mechanisms in RETaO(4) has hindered performance optimization through rare-earth compositional engineering. This study systematically investigates the corrosion behavior of 3-10 component RETaO(4) systems. In situ X-ray diffraction/Transmission electron microscope coupled with Electron backscatter diffraction analysis unveils dynamic reaction pathways during the pre-corrosion heating stage, identifying the crystallization and growth patterns of dominant corrosion product pyrochlore-structured (Ca(2-a-b)RE(a)Al(b))(Ta(2-c-d)Mg(c)Si(d))O(7). A reaction-diffusion mechanism of CMAS corrosion for RETaO(4) is proposed, highlighting the different behaviors of various rare earth elements in the corrosion process. Among eight types of RETaO(4), La(1/6)Nd(1/6)Sm(1/6)Eu(1/6)Gd(1/6)Dy(1/6)TaO(4) exhibits the best corrosion resistance, with a relatively thin corrosion layer and the ability to avoid element segregation and localized infiltration. These findings establish composition-property relationships for designing next-generation corrosion-resistant thermal barrier coatings.