[SY-C5] Symposium C-5

[SY-C5] Atomic Scale Investigation of Plasticity in Laves phases

^○Julien Guenole¹, Fatim-Zahra Mouhib¹, Christoffer Zehnder¹, James Gibson¹, Blazej Grabowski², Sandra Korte-Kerzel¹ (1.Institute of Physical Metallurgy and Metal Physics, RWTH Aachen University, Germany, 2.Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany)

The strengthening mechanisms in magnesium alloys are strongly related to the complex intermetallic precipitates that spread all over the microstructure. In particular, the hard and brittle Laves phases [1] commonly observed in such alloys exhibit a complex atoms stacking with largely unknown plasticity mechanisms [2].

We propose here a numerical atomistic approach at the cross-road of experiments and ab initio simulations, to shed light on the responsible mechanisms for the plasticity in hexagonal Mg₂Ca (C14) Laves phases. Elastic and plastic properties of bulk Laves phase are investigated by both first principle and classical atomistic simulations. Molecular dynamics/statics simulations with a robust MEAM interatomic potential are performed to study the propagation of dislocations, by a combination of nudge-elastic-band (NEB) methods and nano-mechanical tests. In particular, the cross-slip to pyramidal slip planes, the propagation of dislocations in the basal plane by the so called synchroshear mechanism [3,4] and the influence of temperature on slip systems activation, are investigated at the atomic scale. All these results are finally correlated and discussed by considering experimental findings, especially from micro-pillar compression tests. Our goal is to improve the understanding of the largely unknown plasticity of Laves phases.

References:
[1] - F. Laves and H. Witte, Metallwirtsch. Metallwiss. Metalltech. 15, 840 (1936).
[2] - M.F. Chisholm, et al., Science 307, 701 (2005)
[3] - P.M. Hazzledine et al., MRS Proceedings 288, 591 (1992)
[4] - P.M. Hazzledine and P. Pirouz, Scripta metallurgica et materialia 28, 1277 (1993).