Dislocation content in random high angle grain boundaries

Abstract

The dislocation content of high angle grain boundaries in a random FCC polycrystal was determined through large-scale molecular dynamics modeling and the dislocation extraction algorithm for detecting dislocations. This method provides a means of calculating grain boundary dislocation content in atomistic samples from relaxed atomic positions. It was found that a large fraction of the boundaries studied contained significant densities of lattice and partial dislocations as part of their structure. The observed dislocation content varied widely depending on the boundary’s specific geometrical parameters. The average grain boundary dislocation segment length observed is of the order of the grain boundary thickness, as calculated from the simulation data. The dislocation densities changed significantly during virtual tensile straining of the samples, as dislocations are emitted from and absorbed at grain boundaries. These results are discussed in the context of the role of the multiplicity of possible grain boundary structures on the deformation response of polycrystalline materials.