Molecular dynamics study on characteristics of misfit dislocations in Ni-based superalloys

By using molecular dynamics simulation, misfit dislocation networks are made on semi-coherent interfaces in a laminate structure of Ni and Ni3Al single crystals. The core structure of the networks is discussed in detail, focusing on the different atomic configuration at the interfaces; e.g. with or without Al atoms on the Ni3Al side. It is revealed that the networks can be a source of partial dislocation loops under the external loading; however, the loops tend to form immobile wedge-like stacking faults, analogous to the stacking fault tetrahedron (SFT), near the interface with Al atoms. On the other hand, the loops propagate into both Ni and Ni3Al phases, from the network dislocations on the interface without Al atoms.