Influence of stress state on the evolution of misfit dislocation networks in a Ni-based single crystal superalloy

The structural evolution of interfacial dislocation networks in a Ni-based single crystal superalloy under various stress states was simulated by molecular dynamics (MD). From the simulation, we found that the dislocation network exhibits different deformation and damage mechanisms under various stress states. The square dislocation network at the (100) phase interface is the easiest to damage under a [100] uniaxial load, but more difficult to damage when multi-axial loads are applied. This suggests that the application of a [100] direction axial load is the key factor for the damage of the square dislocation network, which leads to failure of the Ni-based single crystal superalloy under the [100] axial centrifugal load. Moreover, based on MD simulations, the effects of the stress state on gamma' rafting were explored. The results indicate that the morphology of gamma' raft depends on the damage structures of the dislocation network under various stress states.