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

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

Modelling dislocation in binary magnesium based alloys using atomistic method

In the wake of developing biodegradable metallic implants for orthopedic practice or lightweight structural components for the automotive industry, both fundamental and applied research on magnesium and its alloys regained a high interest in the last decade. As of today, the major issues delaying the integration of the magnesium technology in the medical and automotive industries are (i) a lack of ductility and (ii) a poor corrosion resistance. Alloying is a common strategy used to improve the ductility and the corrosion resistance. Although density functional theory is a powerful method that allows one to quantify material parameters to be used later in a theoretical model, atomistic methods in the framework of semi-empirical potentials are complementary to density functional theory. While the data obtained from semi-empirical potentials are more qualitative than quantitative, it does not prevent atomistic calculations in the framework of semi-empirical potentials to validate/disprove/enrich an existing theoretical model or even to provide insights for the development of a new theoretical model. The validity of the data derived from atomistic calculations in the framework of semi-empirical potentials depends on the accuracy and transferability of the potentials to capture the physics involved in the problem. In view of modeling the mechanical properties of a binary magnesium-based alloy using semi-empirical potentials, one has to validate the ability of the potentials to capture the physics governing the interactions between the alloying element and the micromechanisms carrying the inelastic behavior. In this chapter, we are reviewing the interaction between alloying elements and (i) stacking faults and (ii) dislocations from the basal and prismatic slip systems