Effects of crystal orientation on stress distribution near the triple junction in a tricrystal γ-TiAl

The mechanical properties of intermetallic γ-TiAl based materials depend strongly on the microstructure. The crystallographic finite element results show that the stress distribution near the grain boundary and triple junctions is very complex. This stress concentration depends on grain orientation and its stiffness matrix of neighboring grains. Grain-boundary analysis should be established on the basis of crystallographic constitutive theory and finite deformation. A three-dimensional anisotropic finite element analysis is used to investigate stresses in the models that were taken from a γ-TiAl. Characteristics of deformation near grain boundaries were illustrated and calculation of stress concentration factor in bicrystal shows that there are stress concentrations near grain boundaries and near edges in hard components that can vary by 14%. Analysis of deformation shows that the ɛxx strain near a grain boundary in a harder grain is higher than the average strain of this grain, and in the softer component, strain ɛxx near grain boundary is lower than the average strain of this grain. In γ-TiAl, stresses at surfaces are significantly different from the interior stresses near triple junction. Stresses in triple junctions can vary by 45% in agreement with previous work reported by Fallahi et al. and near grain boundaries can be 20–30% larger than the average stress in the material.