Intergranular and transgranular crack growth at triple junction boundaries in ordered intermetallics

Coincident site-lattice (CSL) and random grain boundaries (GBs) effects on intergranular and transgranular crack propagation paths in ordered intermetallics that are subjected to high rates of strain are investigated. A three dimensional dislocation density based multiple slip crystalline formulation and computational scheme are used for a detailed understanding and accurate characterization of interrelated deformation and failure mechanisms that can occur due to the generation, trapping, interaction, and annihilation of mobile and immobile dislocation densities that are generally associated with finite strain high strain-rate plasticity in L1(2) ordered intermetallics. Results from this study indicate that intergranular crack growth is along the GBs, normal to the stress-axis, and is due to the dominance of normal stresses in the crack-tip region. Transgranular crack growth is along slip-planes, and is due to the dominance of shear stresses in the crack-tip region. (C) 1998 Elsevier Science Ltd. All rights reserved.