The correlation between dislocation structure and work‐hardening behaviour of molybdenum single crystals deformed at 293° K

Abstract

Abstract The dislocation structure of high‐purity molybdenum single crystals after tensile deformation at 293° K is studied by transmission electron microscopy. Dislocation and debris densities were determined as function of strain. The stress–strain curve is characterized by a high initial work‐hardening rate and a subsequent stress plateau. At low strains long jogged screw dislocations and dislocation debris predominate while at higher strains additionally large dislocation tangles are formed. The resolved flow stress τ and screw dislocation density ϱ 1 obey τ = τ 0 + α 1 G b √ϱ 1 with α 1 = 1.1. It is suggested that the interaction between primary and secondary screws involving the formation of jogs, debris, and attractive dislocation junctions is the relevant dislocation strengthening mechanism.