Hot corrosion of high-entropy hafnate for thermal barrier coating material subjected to molten CMAS

The calcium magnesium aluminosilicate (CMAS) corrosion behavior of high entropy (La 0.2 Ce 0.2 Pr 0.2 Sm 0.2 Eu 0.2 ) 2 Hf 2 O 7 (HEF) thermal barrier coatings (TBCs) material heated at 1300℃ was first investigated. The results show that CMAS can quickly dissolve HEF, and then re-precipitate multicomponent apatite (Ap) solid solutions and HfO 2 stabilized by rare earth (RE). Moreover, the re-precipitation rate of the Ap phase has a positive relation with RE cation size. The gradient re-precipitation of the Ap phase avoids the initiation of cracks in the reaction layer. It reveals that HEF exhibits good resistance to CMAS corrosion, which is regarded as a novel TBCs material. • The CMAS corrosion behavior of high entropy (La 0.2 Ce 0.2 Pr 0.2 Sm 0.2 Eu 0.2 ) 2 Hf 2 O 7 is first investigated. • (La 0.2 Ce 0.2 Pr 0.2 Sm 0.2 Eu 0.2 ) 2 Hf 2 O 7 subjects to CMAS corrosion through dissolution and re-precipitation process. • The re-precipitation rate of the apatite phase has a positive relation with rare earth cation size. • (La 0.2 Ce 0.2 Pr 0.2 Sm 0.2 Eu 0.2 ) 2 Hf 2 O 7 exhibits good CMAS corrosion resistance performance after 40 h of heat treatment at 1300℃.