The internal stress state in lamellar PST-crystals of the intermetallic alloy TiAl after compressive deformation

The microstructure of gamma-based TiAl alloys often exhibits grains with an internal lamellar structure consisting of alternating gamma-TiAl and alpha (2)-Ti3Al lamellae. Even in undeformed material, internal coherency stresse s, due to the lattice misfit between the two phases and the tetragonality o f the gamma-phase are present. The goal of this work was to investigate the evolution of internal strains induced by compressive deformation of PST-sp ecimens of the alloy TiAl at room temperature and at 800 degrees C. The res ults of X-ray measurements of different peak profiles, performed with a spe cial high-resolution double-crystal diffractometer are reported, which reve aled the dependence of the deformation-induced internal strains on the orie ntation of the lamellar boundaries with respect to the axis of deformation. (C) 1999 Elsevier Science Ltd. All rights reserved.