Nanoindentation simulation of Ni-base single-crystal superalloy with the consideration of interface effect

Nanoindentation made by diamond indenter on pure Ni and the γ/γ'-phase in a Ni-base single-crystal superalloy is simulated respectively with molecular dynamics method. Elasticity modulus and hardness of the two models are calculated. Initiation and growth of dislocations and the influence of misfit dislocations of γ/γ'-phase in Ni-base single-crystal superalloy at different indentation depths are analyzed with center symmetry parameter. Results show that the relationship between indentation load and depth for the two models is similar when the indentation depth below 0.641 nm, indicating that the misfit dislocation on interface little affects the indentation. When the indentation depth reaches 0.995 nm, the dislocation nucleation can be found in misfit dislocations and the crystals that have slipped along {111}-oriented crystal surface in γ-phase. As a result, the indentation load of the latter model decreases and is smaller than that in pure Ni model before the indentation depth reaches 1.487 nm. When the indentation depth reaches 1.307 nm, owing to the inhibition caused by misfit dislocations at the interface, the indentation load for the γ/γ'-phase model in Ni-base single-crystal superalloy increases rapidly.