Atomistic study of plastic deformation in Mg-Al alloys

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:586

Article

Xiao, Wei^1,2  Zhang, Xu¹  Geng, Wen Tong²  Lu, Gang¹ 

[1] Calif State Univ Northridge, Dept Phys & Astron, Northridge, CA 91330 USA

[2] Univ Sci & Technol Beijing, Sch Mat Sci & Engn, Beijing 100083, Peoples R China

关键词: Magnesium alloys;    Dislocations;    Plastic deformation;    Atomistic simulation;   

DOI  :  10.1016/j.msea.2013.07.093

来源: Elsevier

【 摘 要 】

An atomistic study has been carried out to understand plastic deformation in Mg-Al alloys. We investigate the possible plastic deformation mechanisms of intermetallic beta-Mg17Al12 which is a key precipitate phase in Mg-Al alloys. Based on the analysis of the generalized stacking fault energy, we predict the preferential slip systems in this phase and speculate that partial dislocations and complex stacking faults are responsible for its plastic deformation. Using Rice's criterion on ductile-to-brittle transitions, we confirm the intrinsic brittleness of the intermetallic phase. We also simulate the interaction between the basal edge dislocation and dissolved Al particles. We have determined the binding energy between the dislocation and the particles and examined the energetic dependence on the particle size, particle concentration and dislocation-particle distance. The strengthening effect due to the Al solutes is characterized by two quantities - the Peierls stress and the solid solution strengthening factor. The former reflects the changes in dislocation core structure while the latter results primarily from the elastic dislocation-particle interaction. Both quantities are examined and their dependence on particle size and concentration is elucidated. The dislocation core structure and the long-range elastic interaction between the dislocation and the Al particles are also examined. (C) 2013 Elsevier B.V. All rights reserved.

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