HVEM analysis of three-dimensional dislocation structures in Fe crystals deformed at 173 K

Abstract
Three-dimensional dislocation structures formed in iron single crystals by tensile deformation at 173 K were analysed from stereoscopic pairs of 1000 kV electron micrographs. The specimen sections were 1·6 to 2·5 μm thick. Although the crystals were oriented for single slip, nearly equal densities of long screw dislocations were found on the primary and conjugate slip systems, a third slip system becoming active at larger strains. From the experimentally determined dislocation parameters only, Takeuchi's (1969) theory of low-temperature work hardening predicted the experimental shear stress—shear strain curve beyond the region of discontinuous yielding.