The effect of multiple species in solute strengthening in aluminium – A molecular dynamics study

The strength of a metallic alloy is controlled by the collective contribution from different strengthening mechanisms. To develop a complete numerical framework for the flow stress in alloys, it is necessary to understand the different mechanisms isolated, as well as knowing how they interact and affect each other. Several models for the solute strengthening contribution based on first principle calculations have been developed in the recent years [1,2]. These models have treated single solute species and predicted flow stress in good agreement with experimental results. The effect of multiple species has not yet been investigated with the same level of complexity, resulting in a lack of understanding of solute strengthening. The effect of multiple solute species is often a source of error in higher scale strengthening models, where the effective contribution from solute strengthening is calculated by a linear combination of the different species, or scaled by an effective concentration.

In this work, we have conducted a molecular dynamics study of an aluminium alloy with a random distribution of silicon and magnesium solutes. The simulations are combined with an analytical study of the isolated systems with a single solute species and a mobile dislocation. Models used to calculate the solute strengthening contribution at higher length scales are investigated, as an attempt to validate their approach. The empirical parameters used in these models are calculated by molecular dynamics. In addition, the study aims to broaden the understanding of dislocation bow out, and how it affects the mobility of dislocations.

[1]:https://doi.org/10.1016/j.actamat.2016.09.046

[2]:https://doi.org/10.1038/nmat2813