Formation and stability of saturated bundled structure (SBS) in Ti₃Al single crystals cyclically deformed by double prism slip

Formation and stability of deformation substructure in fatigued Ti₃Al single crystals deformed by double prism slip were examined under different applied strain amplitude (Δε). The specimens were initially fatigued at Δε = ± 0.2% or ±0.3% for 1 × 10⁴ cycles and subsequently cyclically deformed after the change in Δε from ±0.2% to ±0.3% or from +0.3% to ±0.2%. The saturated bundled structure (SBS) was composed of the bundles with high density of edge dislocations aligning along [0001] and screw dislocations between the bundles were formed in specimens fatigued at initial Δε to the saturated stage. The bundles in the SBS were developed and expanded after the increase in Δε to ±0.3%, while the rearrangement of screw dislocations occurred and some parts of the saturated edge bundles were removed after the decrease in Δε to ±0.2%. The thermal stability of the fatigued substructure was examined in order to understand the formation process of edge dipoles and debris in the SBS. The change in the maximum shear stress amplitude and the Bauschinger effect were also examined during cyclic deformation.