Interaction between deformation and lamellar interfaces in polysynthetically twinned (PST) crystal of TiAl

Interactions between gliding dislocation and twins with lamellar interfaces have been studied by TEM. It is found that α₂/γ interfaces severely inhibit the twin propagation and dislocation glide, which induces high yield strength and low plasticity at the hardening orientation in PST crystals. There exists the change of deformation mode from twinning to dislocation gliding at γ/γM and γ/γP interfaces, which results from the facts that interfaces inhibit the twin propagation and accommodate the deformation. Comparatively, γ/γT interfaces have less effect on inhibiting the deformation process.