Effect of Re on lattice trapping in γ′-Ni3Al cracks by atomistic simulation

The effect of Re on the lattice trapping at three different crack orientations in gamma'-Ni3Al was studied using the molecular dynamics (MD) method with a Ni-Al-Re embedded-atom-method (EAM) potential. The simulation results showed that the lattice trapping limits (K-IC(+/-)) were not influenced by a single Re atom, while they were influenced by additions of 3 at.% or 6 at.% Re atoms. The calculation values of K-IC(+/-) increased with the increasing of Re concentration. This revealed that the strength of gamma'-Ni3Al can be effectively improved by Re addition, which was in agreement with previous studies. Furthermore, the lattice trapping ranges (Delta K) were small (never exceeded 4% of the theoretical Griffith load K-th(G)) for all the crack systems with or without Re. At different crack orientations for the crack systems with the same Re concentration, there were different lattice trapping limits. Moreover, there were bendings of atomic rows near the Re atoms. This is due to the bonding strength of Ni-Re is stronger than that of Ni-Al, which was confirmed by the discrete-variational method (DVM) calculation. (C) 2014 Elsevier B.V. All rights reserved.