Atomic Mechanisms of Plasticity Nucleation and Development in Nanocrystalline Ni

DS Kryzhevich and AV Korchuganov and KP Zolnikov, PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019, 2167, 020187 (2019).

DOI: 10.1063/1.5132054

The atomic mechanisms of nucleation and development of plasticity in nanocrystalline nickel under mechanical loading were studied. The simulated crystallite had the shape of a parallelepiped and contained grains of the equal size with large disorientation angles. The specimen grips shifted at a constant speed and compressive forces were applied to them. Periodic boundary conditions were simulated in other directions. It was found that plastic deformation always begins to nucleate in the region of the triple junction. One of the atomic mechanisms of plasticity is the initiation of a stacking fault in the triple junction region. At the same time, in the junction area, compressive stresses are formed along one of the jointing grain boundaries, and tensile stresses are formed along the other. An increase in the stresses in the junction area leads to the formation of a stacking fault and its propagation to the volume of one of the grains. The migration of grain boundaries in the simulated nickel crystalline is another atomic mechanism of plasticity. As a result of grain boundary migration, the grain sizes change.

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