Atomistic simulations of the interaction of basal dislocations with MgZn2 precipitates in Mg alloys

The interaction between Mg edge basal dislocations and rod-shaped β1′-MgZn2 precipitates was studied by atomistic simulations using a new interatomic potential. The atomistic model was carefully built taking into account the experimental information about the orientation relationship between the mat...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2020-06, Vol.788, p.1, Article 139555
Main Authors: Esteban-Manzanares, G., Alizadeh, R., Papadimitriou, I., Dickel, D., Barrett, C.D., LLorca, J.
Format: Article
Language:English
Subjects:
Atomistic simulations
Chemical precipitation
Computer simulation
Crystallography
Magnesium base alloys
Mg-Zn alloys
Orowan loops
Precipitate shearing
Precipitates
Precipitation strengthening
Shearing
Slip planes
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Summary:The interaction between Mg edge basal dislocations and rod-shaped β1′-MgZn2 precipitates was studied by atomistic simulations using a new interatomic potential. The atomistic model was carefully built taking into account the experimental information about the orientation relationship between the matrix and the precipitate to ensure minimum energy interfaces. It was found that the dislocations initially overcame the precipitate by the formation of an Orowan loop that penetrated in the precipitate. The precipitate was finally sheared after several Orowan loops were piled-up. The number of loops necessary to shear the precipitate decreased as precipitate cross-section decreased and the temperature increased but was independent of the precipitate spacing. Precipitate shearing did not take place along well-defined crystallographic planes but it was triggered by the accumulation of the elastic energy in the precipitate which finally led to formation of an amorphous layer below and above the slip plane of the basal dislocations. The kink induced in the precipitate by this mechanism was in good agreement with transmission electron microscopy observations.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2020.139555