Molecular dynamics simulations of influence of Re on lattice trapping and fracture stress of cracks in Ni

The influence of Re on the lattice trapping and fracture stress of the five orientation cracks in Ni was investigated using the molecular dynamics (MD) method, with a Ni-Al-Re embedded-atom-method potential. The MD simulations showed that the range (S) of lattice trapping for different crack orientations was small, regardless of the addition of Re. With the addition of 3 at.% or 6 at.% Re, the lower and upper trapping limits (KIC±) increased noticeably and exceeded the theoretical Griffith load. This means that Re-Ni interatomic interactions can prevent the breaking of atomic bonds and can heal cracks. With the addition of Re, the largest and smallest fracture stresses occurred in the (0 1 0)[1 0 1] and (1 0 0)[0 1 0] crack systems, respectively. The MD simulations also showed that in dilute and concentrated Ni (Re) solid solutions, the ranges (R) over which Re atoms restrained the jumps in the bond lengths of atom pairs in neighbouring regions were different. R was proportional to KIC±. In addition, kinks in crack fronts were found not to affect S and R.