Atomic mechanisms of plasticity nucleation in nanocrystalline vanadium

The features of nucleation and development of plasticity in a nanocrystalline vanadium sample under shear loading are studied. The research is carried out within the framework of the molecular dynamics method. The simulated nanocrystalline sample has grains of approximately equal size with large misorientation angles with respect to each other. Calculations have shown that the nucleation of plasticity is associated with the movement of dislocations from the grain interior to their boundaries and the formation of twins. This leads to an increase in the degree of nonequilibrium of grain boundaries. It is noted that the shear loading forms tensile and compressive stresses at the boundaries and junctions of the grains. Tensile stresses can lead to the formation of micropores in the grain boundary region. The behavior of the crystallite is anisotropic with respect to the direction of shear loading, which is due to the small number of grains in the simulated sample.