Journal
ACTA MATERIALIA
Volume 60, Issue 5, Pages 2350-2358Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2012.01.004
Keywords
Magnesium alloys; Dislocations; Plastic deformation; Cross-slip; Density functional theory
Funding
- NSF through the GOA-LI [0825961]
- General Motors, LLC
- NSF
- GM Information Systems and Services
- Div Of Civil, Mechanical, & Manufact Inn
- Directorate For Engineering [0825961] Funding Source: National Science Foundation
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We develop a geometry-based model from first-principles data for the interaction of solutes with a prismatic screw dislocation core, and predict the thermally activated cross-slip stress above room temperature in Mg alloys. Electronic structure methods provide data for the change in prismatic stacking fault energy for different possible fault configurations for 29 different solutes. The direct solute-dislocation interaction energies for solutes that produce stable prismatic screw dislocation cores (K, Na, Sc and Ca) is correlated with stacking fault misfits. This geometric interaction model produces similar prediction errors for all 29 solutes. The model predicts alloys with cross-slip stresses lower than pure Mg for three previously considered solutes (K, Na and Sc) and three new solutes (Ca, Y and Zr). The model also qualitatively confirms the experimental observation that Mg-Li alloys have lower cross-slip stress than pure Mg. In particular, low concentrations of Y are predicted to significantly decrease the cross-slip stress in Mg. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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