Glide of edge dislocations in tungsten and molybdenum

The glide of a dislocation is the fundamental process of plastic deformation in crystalline solids. For body-centered-cubic (bcc) metals, the three-fold core dissociation of screw dislocations has attracted much attention and investigation. In this paper, we present a molecular dynamics study of glide of edge dislocations in bcc tungsten and molybdenum. On the {101} glide planes, the Peierls-Nabarro stress (PNS) of the edge dislocation is found to be (3.75-5.0) x 10(-4)mu and (1.25-2.50) x 10(-4)mu for tungsten and molybdenum, respectively, where mu is the shear modulus. On the glide planes {121}, these two numbers are (8.13-8.75) x 10(-4)mu and (3.75-5.0) x 10(-4) along one direction, and (1.13-1.38) x 10(-3)mu and (6.25-8.75) x 10(-4)mu along the opposite direction. The asymmetry of the PNS on the {121} planes is attributed to the asymmetrical dislocation core structure. During the glide process on {101} planes, the three constituent planes of an edge dislocation displace in sequence. The glide on {121} planes involve two such subsequent displacements, since the core consists of two non-equivalent planes. (C) 2003 Elsevier B.V. All rights reserved.