TEXTURES AND PLASTIC ANISOTROPY IN GAMMA-TIAL

A polycrystalline alloy of composition Ti-36 wt % Al consisting mainly (about 95 vol. %) of gamma-TiAl has been deformed in compression at 450-degrees-C as well as in rolling at 1050-degrees-C. The textures of the deformed specimens were measured and analyzed in terms of orientation distribution functions (ODFs). The textures after hot rolling show a cube-like component (100) [010] with an alignment of the c-axis with the transverse direction. A comparison of measured compression textures with those simulated on the basis of the Taylor theory of polycrystal deformation leads to the following conclusions. Both the "easy" {111}[110] and "hard" {111}[101]-slip modes of deformation occur in gamma-TiAl at 450-degrees-C. The critical resolved shear stresses (CRSSs) for these two slip modes differ by a factor of less than 2, the CRSS for {111}[110]-slip being higher than that for {111}[101]-slip. The rolled specimens show a pronounced plastic anisotropy, which can only be explained on the basis of microstructural considerations.