Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 26: Computational Materials Modelling V - Fracture and Other Failure Mechanisms
MM 26.2: Vortrag
Dienstag, 27. März 2012, 12:15–12:30, TC 006
Atomistic simulations of grain boundary fracture in tungsten bicrystals — •Johannes J. Möller and Erik Bitzek — Lehrstuhl WW1: Allgemeine Werkstoffeigenschaften, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Deutschland
Brittle crack propagation in polycrystals frequently occurs along grain boundaries. Understanding the influence of grain boundary character (misorientation, interface plane, atomic structure) on the fracture behavior is therefore important for modeling fracture of polycrystalline materials. Although atomistic simulations are ideally suited to investigate the details of grain boundary fracture, relatively few systematic simulation studies exist.
Here we present results of atomistic fracture simulations in symmetrical low-Σ tilt grain boundaries in tungsten modeled by the Finnis-Sinclair potential. The fracture behavior (brittle crack advance, dislocation emission, twinning) and the critical stress intensity factors KIc were determined by molecular statics simulations.
Asymmetrically oriented slip systems lead to different fracture behavior in opposing crystallographic propagation directions. The simulations show that KIc for brittle fracture along grain boundaries can also dependent on the crack propagation direction and can be larger than the KIc for brittle fracture in single crystals of the corresponding orientation. The results are discussed in terms of thermodynamic and kinetic aspects, and the concept of grain boundary trapping is introduced. Finally, consequences for mesoscopic models of grain boundary fracture are addressed.