Effects of Vacancies on Deformation Behavior in Nanocrystalline Nickel

The effects of vacancies on deformation of nanocrystalline Ni have been investigated by experiments and molecular dynamics (MD) simulations. In the experiments, nanocrystalline Ni specimens containing different numbers of vacancies were produced by electrodeposition and annealing, and their mechanical properties were investigated by tensile tests. As a result, the yield stress and fracture stress for the specimen containing more vacancies were lower than those for the one containing fewer vacancies. The MD simulations showed that the grain boundary energy is increased by the presence of vacancies in the grain boundary, however, that an increase in grain boundary energy with straining is reduced by the presence of vacancies in the grain boundary. The results of the experiments and simulations suggested that there is a correlation between the grain boundary energy characteristics and the mechanical properties of the nanocrystalline Ni.

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