Tensile deformation of fcc Ni as described by an EAM potential

D Farkas and L Patrick, PHILOSOPHICAL MAGAZINE, 89, 3435-3450 (2009).

DOI: 10.1080/14786430903299329

We present the results of a large-scale atomistic study of tensile deformation in a virtual fcc polycrystalline sample with columnar grain structure and a 110 texture. The atomic interaction was described by a volume-dependent central interatomic potential based on first principle calculations and experimental data for fcc Ni. The sample contained nine grains of 40 nm average size, created using a Voronoi construction with a common 110 axis, so that the grain boundaries were all pure tilt with random misorientation angles and crystallographic orientation of the grain boundary plane. We report the stress-strain behavior of the sample and the particular details of dislocation emission and dislocation interaction. Different grain boundaries acted as emission sites at different stresses due to their different local structure and orientation with respect to the applied stress. It was found that boundaries close to a twin misorientation can emit dislocations easily and become closer to the twin misorientation as a result of the emission process. Low angle boundaries were observed to disappear as a result of the deformation process. The emission of leading and trailing Shockley partials was observed and as the deformation proceeds, dislocation debris accumulates in the sample. The results also show that, as the deformation proceeds, the strain can localize in certain grains and grain regions, driven solely by the particular local structure and orientation of the various grain boundaries.

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