Designing magnesium alloys from density-functional theory and atomistic models

Magnesium alloys have a high strength-to-weight ratio and are therefore of interest to transportation industries as light weight alternatives to heavier non-ferrous and ferrous alloys. However, broader application of wrought Mg alloys in ground transportation vehicles, for example, has been limited by low room temperature ductility, poor formability, and corrosion. The low polycrystalline ductility is a result of the yield strength anisotropy of the HCP crystal structure of Mg. The search for possible alloying routes involve understanding how dislocations--fundamental carriers of plastic deformation--interact with solute elements. Over the past decade, significant effort has gone into the modeling of dislocations with first principles density-functional theory along with interactions with solutes. This includes flexible boundary condition methods to accurately predict dislocation cores, density-functional theory energy density methods to compute dislocation core energies, direct computation of solute interactions as well as intermediate modeling approaches to accelerate the computation of solute interactions. In addition to accurate data, we can understand the effect of solutes their environment and the correlation with dislocation interactions. This fundamental data directly parameterizes larger scale models to identify possible alloying routes beyond what has been explored by traditional metallurgical approaches.