The effect of vacancy concentration on the migration rate of the tilt boundaries in nickel: molecular dynamics modeling

The molecular dynamics method was used to study the effect of the vacancy concentration on the migration rate of high-angle tilt grain boundaries with misorientation axes $\langle$111$\rangle$ and $\langle$100$\rangle$ in nickel. It is shown that the dependence of the migration rate of grain boundaries on the vacancy concentration is nonmonotonic and has a maximum at a concentration of vacancies introduced at the initial stage of about 1%. With a further increase in the concentration, especially above 4%, the migration rate of such boundaries decreases as a result of dragging the boundaries by low-mobile vacancy clusters attached to it, which can no longer be sorbed by the boundary, as in the case of relatively small clusters.