Abstract
Cyclic deformation and fatigue behaviour of Ti-Al crystals containing unidirectionally aligned lamellae have been investigated by focusing on the effects of total strain amplitude and the angle ⊘ between the loading axis and the lamellar planes. Cyclic tension-compression loading was carried out at room temperature at total strain-controlled amplitudes of \pm0.3, \pm 0.5 and \pm 1.0%. At ⊘ = 0° a high maximum stress was obtained and the cyclic hardening became strong with increasing number of cycles and total strain amplitude. The α2-phase acts as a barrier to the motion of dislocations in the γ-phase. Specimens with ⊘ = 45°, on the other hand, deformed at low stress and the maximum stress reached saturation after showing a slight cyclic hardening at an early stage of deformation. Extrusions due to the to-and-fro motion of dislocations were observed in both specimens but were formed markedly at ⊘ = 45°.