Basal dislocation/precipitate interactions in Mg-Al alloys: an atomistic investigation

Abstract

The interaction between edge basal dislocations and $\beta$-Mg${}_{17}$Al${}_{12}$ precipitates was studied using atomistic simulations. A strategy was developed to insert a lozenge-shaped Mg${}_{17}$Al${}_{12}$ precipitate with Burgers orientation relationship within the Mg matrix in an atomistic model ensuring that the matrix/precipitate interfaces were close to minimum energy configurations. It was found that the dislocation bypassed the precipitate by the formation of an Orowan loop, that entered the precipitate. Within the precipitate, the dislocation was not able to progress further until more dislocations overcome the precipitate and push the initial loop to shear the precipitate along the (110) plane, parallel to the basal plane of Mg. This process was eventually repeated as more dislocations overcome the precipitate and this mechanism of dislocation/precipitate interaction was in agreement with experimental observations. Moreover, the initial resolved shear stress to bypass the precipitate was in agreement with the predictions of the Bacon-Kocks-Scattergood model.

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Cited by in corpus (7)

• Strengthening of Al-Cu alloys by Guinier-Preston zones: predictions from atomistic simulations
• Dislocation dynamics prediction of the strength of Al-Cu alloys containing shearable ${\theta }^{\prime \prime }$ precipitates
• Strengthening magnesium by design: integrating alloying and dynamic processing
• A generalized line tension model for precipitate strengthening in metallic alloys
• Density functional simulations of pressurized Mg-Zn and Al-Zn alloys
• Atomistic simulations of the interaction of basal dislocations with MgZn${}_2$ precipitates in Mg alloys
• Interactions between basal dislocations and ${\beta }_1^{\prime }$ precipitates in Mg-4Zn alloy: mechanisms and strengthening