Dispersed particle and triple junction interactions in aluminum alloys

The interrelated effects of dispersed particle interfaces and grain-boundary (GB) misorientations on the dynamic compressive deformation of high strength aluminum alloys have been investigated using an eigenstrain-based formulation coupled with dislocation-density based crystalline plasticity and a microstructurally based finite element framework. This formulation, which accounts for the unrelaxed plastic strains associated with the interfacial behavior of dispersed particles, such as Orowan looping, was used to model an aluminum tri-crystal with different distributions of dispersed particles and GB misorientations. Slip was relatively homogeneous and associated with initially preferential slip planes for low angle random GB misorientations. Particle dispersion had a greater effect on the deformation behavior for the high angle random GB misorientation tri-crystal, with dislocation density generation at the particle–matrix interface resulting in localized particle-controlled shear banding, which can inhibit transgranular shear banding caused by the triple junctions. Larger dispersed particles led to higher stress concentrations at the triple junction and higher tensile pressures at the particle–matrix interfaces.