Dresden 2017 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 20: Computational Materials Modelling - Defect structure and formation

MM 20.2: Talk

Monday, March 20, 2017, 17:15–17:30, IFW B

Ab-initio study of the interplay of hydrogen and microstructure in Ni-based superalloys — •Poulumi Dey, Zahra Tarzimoghadam, Dirk Ponge, Eunan McEniry, Tilmann Hickel, Dierk Raabe, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung GmbH, D-40237 Düsseldorf, Germany

Ni-based superalloys with their excellent corrosion resistance are attractive for applications where exposure to hydrogen is inevitable such as sour gas environments in oilfields. The adverse impact of hydrogen on the desired mechanical properties of these alloys, however, often restricts the acceptable strength levels of these materials. In the present work, we perform ab-initio calculations to establish the fact that the delicate behavior of hydrogen sensitively depends on microstructure features present in the superalloy. In particular, we consider the volume fractions of different precipitate phases which can be experimentally adjusted by annealing and aging conditions. With the aid of density functional theory (DFT), we perform a quantitative analysis of the hydrogen solution enthalpies within the precipitates and their interface to the matrix material. The study thus provides crucial information about the impact of chemistry and crystal structure on the hydrogen solubility and diffusivity at the interfaces as well as possible nucleation points for hydrogen-induced fracture in the material.