Measurement and modeling of orthotropic elastic behavior of grains in a gamma titanium aluminide alloy

Gamma titanium aluminide (γ-TiAl) alloys have been under development for use in rotating components for gas turbine engines. Detailed three-dimensional (3D) grain-level finite element models are being developed to predict damage initiation and accumulation in γ-TiAl during service loading. These models require knowledge of the orthotropic nature of the elastic and plastic deformation of individual grains. While the elastic properties of gamma and alpha-2 single-phase materials have been extensively studied, the elastic response of fully lamellar two-phase materials has not received the same degree of attention. This paper describes an integrated experimental and analytical approach to deduce the elastic grain properties in a γ-TiAl. Specimens with gage sections composed of specifically-oriented individual lamellar grains were tested in tension. 3D finite element analyses were used to deduce the elastic grain properties. These grain properties were used to accurately predict the elastic properties of polysynthetically-twinned (PST) and polycrystalline γ-TiAl.