Effect of solute atoms on dislocation motion in Mg: An electronic structure perspective

Abstract

Solution strengthening is a well-known approach to tailoring the mechanical properties of structural alloys. Ultimately, the properties of the dislocation/solute interaction are rooted in the electronic structure of the alloy. Accordingly, we compute the electronic structure associated with, and the energy barriers to dislocation cross-slip. The energy barriers so obtained can be used in the development of multiscale models for dislocation mediated plasticity. The computed electronic structure can be used to identify substitutional solutes likely to interact strongly with the dislocation. Using the example of a-type screw dislocations in Mg, we compute accurately the Peierls barrier to prismatic plane slip and argue that Y, Ca, Ti, and Zr should interact strongly with the studied dislocation, and thereby decrease the dislocation slip anisotropy in the alloy.

Solute strengthening in random alloys

“…We also remind ourselves that an underlying assumption of the present class of models is that solutes do not significantly distort the dislocation core structure of the matrix material (or effective matrix) [8,9,10]. When such large distortions do occur, they are accompanied by large reductions in the system energy, e.g.…”

“…These interactions fall into two basic categories: those where the solute changes or reconfigures the dislocation core structure and those where the solute leaves the topology of the core structure largely intact. When a solute changes the core structure, the strengthening effects depend on the specific details of the interaction and how the core structure is changed [8,9,10,11]. We do not envision any general theory for this important class of problems; presumably the changes in structure and associated energies are very specific to the solute, the matrix, and the dislocation character.…”

Atomistic calculations of dislocation core energy in aluminium

“…However, this separation distance is significantly larger than the minimum core radius discovered above. To better understand how the energetics of the dissociated structure relates to our results, we compute the energy change when a perfect edge dislocation dissociates into two partials (similar to the approach used by [27]). Since we are focusing on the core structure, we only consider an isolated extended dislocation in an infinite medium (rather than periodic arrays of dislocations like we did above).…”

A Review of Multi-Scale Computational Modeling Tools for Predicting Structures and Properties of Multi-Principal Element Alloys

“…Solute strengthening is an important characteristic of MPE alloys which causes improvement in the strength of these alloys compared to their constitutes [98]. It is well known that the strength of materials can be changed by adding more solute atoms with large differences in shear moduli and size of solvent and solute atoms [119][120][121].…”