Glide systems and Peierls stresses in fcc and bcc metals from phonon energies

Abstract

As an approach to correlate atomistic and mechanical properties of metallic materials, work has recently been performed in order to understand the surface energy for brittle fracture in terms also of frequencies of the normal modes of vibration of the metal itself. In the same frame, the interpretation of the glide systems in fcc and bcc metals has been attempted and is presented here. The one-dimensional model developed by Frenkel and Kontorova for an edge dislocation is reformulated in order to take advantage of the knowledge of interplanar force constants experimentally accessible by neutron inelastic scattering. The numerical solution is given following the procedure proposed by Hobart. Peierls energies and critical shear stresses have been thus evaluated on an atomistic level for some glide systems in fcc (Al, Cu, Ni) and bcc (Fe, W, Ta, Nb) metals.