A first-principles density functional theory investigation was made of vacancy segregation near to the nickel Σ = 5 (210) grain boundary under an applied stress. The total energy calculations within generalized-gradient approximation revealed that the applied stress could hardly alter the energy preference of a vacancy at different atomic layers away from the grain boundary plane, especially in the range of practical stresses. The segregation enthalpy, nevertheless, gets more (less) significant with the increasing compressive (tensile) stress as a result of the vacancy being smaller in volume at the boundary. The first-principles result that high-angle tilt grain boundaries in nickel were likely to act as a source (sink) in emitting (absorb) vacancies under a tensile (compressive) stress was not in accordance with the prediction based upon a thermodynamic model. The numerical results were combined with electronic structure analysis.

Effect of Applied Stress on Vacancy Segregation near the Grain Boundary in Nickel. W.Xiao, C.S.Liu, Z.X.Tian, W.T.Geng: Journal of Applied Physics, 2008, 104[5], 053519