title: Plastic anisotropy and dislocation trajectory in BCC metals.
abstract: Plasticity in body-centred cubic (BCC) metals at low temperatures is atypical, marked in particular by an anisotropic elastic limit in clear violation of the famous Schmid law applicable to most other metals. This effect is known to originate from the behaviour of the screw dislocations; however, the underlying physics has so far remained insufficiently understood to predict plastic anisotropy without adjustable parameters. Here we show that deviations from the Schmid law can be quantified from the deviations of the screw dislocation trajectory away from a straight path between equilibrium configurations, a consequence of the asymmetrical and metal-dependent potential energy landscape of the dislocation. We propose a modified parameter-free Schmid law, based on a projection of the applied stress on the curved trajectory, which compares well with experimental variations and first-principles calculations of the dislocation Peierls stress as a function of crystal orientation.
authors.affiliation: DEN-Service de Recherches de Métallurgie Physique, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.|Institut Jean Lamour, Université de Lorraine - CNRS, F-54011 Nancy, France.
authors.forename: Lucile
authors.initials: L
authors.lastname: Dezerald
authors.affiliation: Institut Lumière Matière, Université Lyon 1 - CNRS, F-69622 Villeurbanne, France.
authors.forename: David
authors.initials: D
authors.lastname: Rodney
authors.affiliation: DEN-Service de Recherches de Métallurgie Physique, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
authors.forename: Emmanuel
authors.identifier: http://orcid.org/0000-0002-0995-6071
authors.initials: E
authors.lastname: Clouet
authors.affiliation: DEN-Service de Recherches de Métallurgie Physique, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
authors.forename: Lisa
authors.initials: L
authors.lastname: Ventelon
authors.affiliation: DEN-Département des Matériaux pour le Nucléaire, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
authors.forename: François
authors.initials: F
authors.lastname: Willaime