Numerical simulation of plastic deformation and fracture in polysynthetically twinned (PST) crystals of TiAl

Plastic deformation and fracture in polysynthetically twinned (PST) crystal s of TiAl have been simulated by using periodic unit cells representing the relaxed-constraint model recently proposed by Lebensohn et al. [Acta Mater . 46 (1998) 4701-4709] for the co-deformation of the lamellar compound of P ST-TiAl. The unit cells contain both intermetallic phases, alpha (2)-(Ti3Al ) and gamma-(TiAl). Furthermore, the six orientation variants of the gamma -phase are also considered. The constitutive behaviour of both phases is de scribed by crystal plasticity, and the damage behaviour has been implemente d by means of cohesive elements. The unit cells have been used as submodels for multi-scale finite element simulations of compression tests acid fract ure mechanics tests of notched micro-bend specimens. It is shown that the a nisotropy of plastic deformation and damage in PST-TiAl can be well represe nted. (C) 2000 Elsevier Science B.V. All rights reserved.