Microstructural influences on the local and global deformation of TiAl polycrystal investigated by experiments and numerical multi-scale approach incorporating crystal plasticity FE model

The influences of the microstructrual heterogeneity on the local and global mechanical behavior of a TiAl polycrystal has been investigated with experiments and numerical modeling. Two types of microstructure, duplex and near-lamellar, which are classified according to the presence of globular grains (consists of g-phases) and lamellar colonies (consists of a2+g-phases), have been studied. The representative microstructures were calculated from SEM and TEM analysis and were incorporated in a two-scale FE model. The micromechanics of deformation of the phases are described in a crystal plasticity FE model. With this polycrystal modeling approach microstructure dependent alloy properties were reliably predicted, with focus on the influence of the microstructural heterogeneity on the elastic properties at grain scale, anisotropic dependency of the material yield and contribution of dislocation-slip of the phases to the plastic deformation at local and global scale