Berlin 2012 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 26: Computational Materials Modelling V - Fracture and Other Failure Mechanisms
MM 26.1: Talk
Tuesday, March 27, 2012, 12:00–12:15, TC 006
First principles study of brittle cleavage processes in FeTi — •Li-Fang Zhu1, Martin Friák1, Antje Schlieter2,3, Uta Kühn2,3, Jürgen Eckert2,3, and Jörg Neugebauer1 — 1Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany — 2IFW Dresden, Germany — 3Dresden University of Technology, Dresden, Germany
Thorough understanding of atomistic mechanisms that are responsible for brittle failure of materials is crucial for many engineering applications. We employ density functional theory calculations to study the brittle cleavage under loading mode I in an important structural intermetallics, FeTi, along [100], [110], [111] and [211] directions. The calculated energy vs. separation curves are found to follow universal binding energy behavior (see e.g. [1]) and allow to determine the corresponding surface energies γ, cleavage energy Gb, and theoretical strength σb. Relations between cleavage and elastic properties are explored by applying the generalized Orowan-Gilman model [2]. Our study shows that the brittle loading along the [110] direction has the lowest strain to fail, as well as lowest cleavage energy and theoretical strength. These findings indicate that the preferred fracture occurs in single crystal FeTi along the (110) plane. We also find an onset of magnetism in FeTi when increasing the distance between the cleavage planes and show how it is responsible for termination-specific surface energy reductions.
[1] J. H. Rose, J. R. Smith, J. Ferrante, Phys. Rev. B 28 (1983) 1835.
[2] E. Orowan, Rep. Prog. Phys. 12 (1949) 185.