Mechanism of thermally-activated prismatic slip in Mg
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{
"id": "1995",
"updated": "2023-11-30T09:18:47.454084+00:00",
"metadata": {
"version": 1,
"contributors": [
{
"givennames": "Xin",
"affiliations": [
"Laboratory for Multiscale Mechanics Modeling, \u00c9cole Polytechnique F\u00e9d\u00e9rale de Lausanne (EPFL), CH-1015 Lausanne, Vaud, Switzerland"
],
"email": "xin.liu@epfl.ch",
"familyname": "Liu"
},
{
"givennames": "William",
"affiliations": [
"Laboratory for Multiscale Mechanics Modeling, \u00c9cole Polytechnique F\u00e9d\u00e9rale de Lausanne (EPFL), CH-1015 Lausanne, Vaud, Switzerland"
],
"familyname": "Curtin"
}
],
"title": "Mechanism of thermally-activated prismatic slip in Mg",
"_oai": {
"id": "oai:materialscloud.org:1995"
},
"keywords": [
"Magnesium",
"Prismatic slip",
"Neural network potential",
"MARVEL"
],
"publication_date": "Nov 30, 2023, 10:18:47",
"_files": [
{
"key": "files.zip",
"description": "Simulation codes and results",
"checksum": "md5:a4fe4e5cc523de6e50aa113bf4cd078e",
"size": 802731625
}
],
"references": [
{
"doi": "10.1016/j.actamat.2023.119402",
"citation": "X. Liu, W. Curtin, Acta Materialia 262, 119402 (2024)",
"type": "Journal reference"
}
],
"description": "Prismatic slip of the screw <a> dislocation in magnesium at temperatures \u2273 150 K is understood to be governed by double-cross-slip of the stable basal screw through the unstable prism screw and back to the basal screw, with the activation energy controlled by the formation energy of two basal-basal kinks. However, atomistic studies of the double-kink process predict activation energies roughly twice those derived experimentally. Here, a new mechanism of prism glide is proposed, analyzed theoretically, and demonstrated qualitatively and quantitatively via direct molecular dynamics (MD) simulations. The new mechanism is intrinsically 3d, and involves the nucleation of a single kink at the junction where a 3d prismatic dislocation loop transitions from the basal screw segment to non-screw prismatic character. The relevant kink energies are calculated using recently-developed Neural-Network Potentials (NNPs) for Mg that show good agreement versus DFT for basal and prism <a> dislocations, enabling a parameter-free analytic model for the activation barrier. Direct MD simulations show both operation of the precise proposed mechanism and a stress-dependent activation barrier that agrees reasonably with the analytic model. Predictions of dislocation velocity compare very well with in-situ TEM data, and macroscopic strength versus temperature can also be understood. Overall, the new intrinsically 3d mechanism for dislocation glide due to single kink nucleation rather than double-kink nucleation explains key features of the prismatic slip in Mg and may have broader applicability in other metals where kink nucleation processes control thermally-activated flow.",
"status": "published",
"license": "Creative Commons Attribution 4.0 International",
"conceptrecid": "1994",
"is_last": true,
"mcid": "2023.185",
"edited_by": 576,
"id": "1995",
"owner": 875,
"license_addendum": null,
"doi": "10.24435/materialscloud:bf-5x"
},
"revision": 9,
"created": "2023-11-28T16:22:28.830920+00:00"
}