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MM: Fachverband Metall- und Materialphysik

MM 41: Computational Materials Modelling VI - Dislocations

MM 41.6: Vortrag

Mittwoch, 2. April 2014, 12:45–13:00, IFW D

Atomistic Simulations of Dislocation-Interface Interactions in the γ/γ′ Microstructure in Ni-based Superalloys — •Juan Wang, Julien Guénolé, Aruna Prakash, and Erik Bitzek — Department of Materials Science and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)

Single crystalline Ni-base superalloys are key materials for turbine blades in modern gas turbines. The microstructure of these alloys consist of cubic γ′ precipitates of Ni₃Al in the L1₂ crystal structure embedded in a γ-matrix of fcc Ni. The interaction of dislocations in the γ channels with the γ′ precipitates is a main factor for the superior strength of these alloys even at high temperatures. The cutting of the dislocations from the γ channels into the precipitates is governed by processes at the atomic scale. However, only few atomistic simulations of the dislocation behavior at the γ/γ′- interface have so far been performed. Here we report on a detailed study of screw and 60^∘ dislocations interacting with a planar γ/γ′-interphase boundary in a quasi-two dimensional set-up. Static calculations as well as molecular dynamic calculations were performed to determine the critical penetration stress and to study the interaction of the channel dislocations with the misfit dislocation network. In addition, the interaction of dislocations with a curved interphase boundary was studied in a fully 3D set-up modeling an experimental microstructure obtained by 3D Atom Probe Tomography. The results of the simulations are discussed in the framework of a multiscale modeling approach to study the mechanical behavior and stability of Ni-based superalloys.