Cyclic Deformation Behavior and Dislocation Structure of Ti-2 At. Pet Al Single Crystals Oriented for Double Prism Slip

摘要

Cyclic deformation behavior and dislocation substructure in the single crystals of Ti-Al alloy containing 2.0 pct Al (by atom) with double prism slip at different cyclic strain amplitudes were examined. The testing results showed that Ti-2Al displayed an initial slight cyclic hardening followed by a striking softening period, and a saturation stage was reached finally. Secondary cyclic hardening was observed for most specimens before failure, specifically at the high cyclic strain amplitudes. The cyclic resolved shear stress-strain curve (CSSC) was observed to contain a plateau in the testing strain range with a saturation plateau stress of about 55 MPa. Trace analysis on the surface of specimens with an optical microscope shows that the (1010) and (1100) double prism slips can be distinguished from the traces on the (0001) surface of the fatigued specimens. The dislocation substructure in the fatigued specimens was examined using a transmission electron microscope (TEM). The typical dislocation configuration is the saturated dislocation bundles, which are tangled on the (1010) and (1100) slip planes and arranged parallel to the [0001] direction.