Atomistic Modeling of the Interphase Structure between Alumina and Al12Fe2Cr Quasicrystal Approximant

Molecular dynamics simulations are performed to study the stability of an fcc metallic interlayer phase between an iron aluminide quasicrystal approximant (QCA) phase (84.2 Al, 5.7 Fe, 5.4 Ni, and 4.7 at.% Cr) and aluminum oxides (α-Al₂O₃ and γ-Al₂O₃). The presence of the interlayer phase was experimentally observed in some regions of the inner diameter surface of a TPBAR cladding tube. The simulations employed existing many-body (MEAM and EAM) interatomic potentials to describe atomic interactions in the interlayer and QCA phases, and Buckingham+Coulomb pair interactions for the alumina and between the alumina and the QCA (or fcc). Interface systems of QCA/alumina, fec/alumina, and QCA/fcc are modeled and the fracture energy of the interfaces is calculated. Based on the fracture energies, for the γ-Al₂O₃, both MEAM and EAM suggest that the fcc interlayer phase would not form. For the α-Al₂O₃, the MEAM predicts that the fcc phase would form, however, the EAM predicts that it forms only if the α-Al₂O₃ is Al-terminated at the interface. For the O-terminated α-Al₂O₃, the EAM predicts the fcc phase would not form, consistent with the results for γ-Al₂O₃.. Authors: Setyawan, Wahyu [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000151928085); Pitike, Krishna Chaitanya [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)]. DOE Contract: AC05-76RL01830. Subjects: 36 MATERIALS SCIENCE