Glide of edge dislocations in tungsten and molybdenum

Abstract

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 {1 1 0} glide planes, the Peierls–Nabarro stress (PNS) of the edge dislocation is found to be (3.75–5.0)×10 −4 μ and (1.25–2.50)×10 −4 μ for tungsten and molybdenum, respectively, where μ is the shear modulus. On the glide planes {1 1 2}, these two numbers are (8.13–8.75)×10 −4 μ and (3.75–5.0)×10 −4 μ along one direction, and (1.13–1.38)×10 −3 μ and (6.25–8.75)×10 −4 μ along the opposite direction. The asymmetry of the PNS on the {1 1 2} planes is attributed to the asymmetrical dislocation core structure. During the glide process on {1 1 0} planes, the three constituent planes of an edge dislocation displace in sequence. The glide on {1 1 2} planes involve two such subsequent displacements, since the core consists of two non-equivalent planes.