Textures and plastic anisotropy in γ-TiAl

Abstract

A polycrystalline alloy of composition Ti-36 wt % Al consisting mainly (about 95 vol. %) of γ-TiAl has been deformed in compression at 450°C as well as in rolling at 1040°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 γ-TiAl at 450°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.