Dislocation core structures and mobilities in MoSi2

Using a modified version of the embedded atom method (EAM) that includes an gular forces; potentials are developed for MoSi2.. The potentials describe the structural and elastic properties in reasonable agreement with experime nt. These potentials are used to calculate the core structures and resistan ce to glide for four straight dislocations that are observed in MoSi2. In c ontrast to previous calculations in materials with simple crystal structure s, such as face-centered cubic metals, it was necessary to use molecular dy namics at elevated temperature to obtain any dislocation mobility. It is fo und that only one of the dislocations, a/2 < 111 > (110) with predominantly edge character, has any significant mobility at reasonable stresses. In on e case, the dislocation dissociates into seven partials at high shear strai n and the response is asymmetric with respect to the direction of the appli ed shear strain. (C) 2001 Acta Materialia Inc. Published by Elsevier Scienc e Ltd. All rights reserved.