Mechanical Properties of Polycrystalline Lamellar TiAl-Intermetallics

TiAl-intermetallics with a fully lamellar microstructure seem to be potential candidates for industrial applications. In this paper a micromechanical study is presented focussing on the room temperature plastic flow behavior of polycrystalline lamellar intermetallics under uniaxial loading conditions. In this course plastic flow of single lamellar grains is analyzed by a crystal plasticity approach which takes into account crystallographic slip and deformation twinning. The dependence of the flow behavior on the angle between the lamellae and the loading direction reveals the highly anisotropic nature of the crystals. Then plastic flow in various lamellar polycrystals is modelled. The highest ductility (low work hardenability and high elongation to fracture) is predicted for microstructures containing grains of low strength arranged in continuous grain clusters.