Abstract:

The evolution of misfit dislocation network at γ/γ′ phase interfaces and the stress distribution characteristics of Ni-based single-crystal superalloys under different temperatures of 0, 100 and 300 K are studied by molecular dynamics (MD) simulation. It was found that a closed three-dimensional misfit dislocation network appears on the γ/γ′ phase interfaces, and the shape of the dislocation network is independent of the lattice mismatch. Under the influence of the temperature, the dislocation network gradually becomes irregular, a/2 [110] dislocations in the γ matrix phase emit and partly cut into the γ′ phase with the increase in temperature. The dislocation evolution is related to the local stress field, a peak stress occurs at γ/γ′ phase interface, and with the increase in temperature and relaxation times, the stress in the γ phase gradually increases, the number of dislocations in the γ phase increases and cuts into γ′ phase from the interfaces where dislocation network is damaged. The results provide important information for understanding the temperature dependence of the dislocation evolution and mechanical properties of Ni-based single-crystal superalloys.

Key words: Ni-based single-crystal superalloy, Molecular dynamics simulation, Dislocation network, Stress distribution