Plastic deformation behaviour and dislocation structure in Ti₃Al single crystals cyclically deforming by prism slip

The effect of prism slip on cyclic hardening and deformation substructure in Ti₃Al single crystals cyclically deformed was examined. Fatigue tests were carried out in a symmetrical tension/compression mode at a fixed total strain amplitude (Δε) of ±0.2% to ±0.4% at room temperature. As Δε and the number of cycles increased, the stress amplitude rose depending on crystal orientation. The cyclic hardening was more accelerated for specimens deformed by double prism slips than for those deformed by single prism slip. At the saturated stage, the edge dipoles and/or multipoles gathered at a localized region and formed bundles with a high residual stress field in specimens deforming by double prism slips, while a high density of dislocations existed the bundled structure did not develop under operation of single prism slip. The peculiar structure containing bundles was called saturated bundled structure (SBS). The formation process of the SBS and the role of the bundled structure on the plastic behaviour are described.