Precipitate size dependence of Ni/Ni3Al interface energy

The interface energy of Ni/Ni3Al dictates the morphology of Ni3Al precipitate and thereby the creep resistance of the Ni-base superalloy. Based on classical molecular dynamics simulations, we report that the interface formation energy depends on the size of Ni3Al precipitate. This dependence is non-monotonic below 20 nm, and converges to a constant value beyond 20 nm. Such dependence is a result of competition between the attractive interaction of dislocations from neighboring interfaces and the strain energy in the Ni3Al precipitate. Further, from elasticity theory, taking into account of the effect of misfit strain, a similar transformation behavior of dislocation dipole's elastic energy versus interface distance was also obtained, which shows the transition point of about 6.2 nm. (C) 2014 Elsevier B.V. All rights reserved.