WS11a2 - Deformation of polysynthetically twinned (PST) crystals and PST bicrystals of TiAl at room temperature

Abstract

We have grown TiAl crystals of a nearly stoichiometric composition composed of a single lamellar grain as well as those composed of two lamellar grains and studied their deformation behaviour at room temperature. The deformation behaviour of lamellar grains depends strongly on the lamellar orientation. Because of such an anisotropy in the deformation behaviour of lamellar grains with respect to the lamellar orientation, a large strain discontinuity and therefore crack initiation may occur near boundaries between coarse lamellar grains. This is suggested to be a reason for low ductility of TiAl with a structure composed of coarse lamellar grains.