Dislocation core structures and mobilities in MoSi2 Original Research Article

Using a modified version of the embedded atom method (EAM) that includes angular forces, potentials are developed for MoSi2. The potentials describe the structural and elastic properties in reasonable agreement with experiment. These potentials are used to calculate the core structures and resistance to glide for four straight dislocations that are observed in MoSi2. In contrast to previous calculations in materials with simple crystal structures, such as face-centered cubic metals, it was necessary to use molecular dynamics at elevated temperature to obtain any dislocation mobility. It is found that only one of the dislocations, a/2〈111〉(110) with predominantly edge character, has any significant mobility at reasonable stresses. In one case, the dislocation dissociates into seven partials at high shear strain and the response is asymmetric with respect to the direction of the applied shear strain.