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.
Highlights
Solution strengthening is a well-known approach to tailoring the mechanical properties of structural alloys
Fracture of magnesium alloys generally occurs as a result of strain concentration generated by piled-up basal dislocation at {1012}-type deformation twin, both of which are introduced in the early stage of the plastic deformation of Mg6
Recent first-principles calculation with flexibleboundary-conditions allowed for the computation of the interaction energy between a dislocation and solute atoms, and to predict the solution strengthening through an energy-based calculation of the equilibrium structure of the dislocation[15]
Summary
Solution strengthening is a well-known approach to tailoring the mechanical properties of structural alloys. The expensive refining process drives up materials costs Another approach is to introduce solute atoms. In a previous report[19], the softening effect of Y within Mg was studied by combining first-principles electronic structure based calculations of generalized stacking fault energies with the Peierls-Nabarro model[20,21]. While these calculations predict the softening effect of Y, the underlying quantum mechanical origins of the effects were not identified.
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