Anisotropic mechanical behavior of textured γ-TiAl caused by the directionality of twinning

After the rolling process of γ-TiAl based alloys, a strong texture similar to the cube textures of fcc-metals with low stacking fault energy occurs. In addition the tetragonal c-axis is aligned in transverse direction of the sheet. At 700 °C compression tests were performed in transverse, rolling and normal direction as well as tensile tests in rolling and transverse direction. The density of deformation twins observed in optical microscopy and TEM-studies increases with decreasing yield stress and strain hardening. Based on these experimental results, the critical resolved shear stresses of the various slip systems in γ-TiAl were modeled in Taylor type simulations. The influence of twinning in the ordered L10-structure on yield stress, strain hardening and ductility is discussed.