Misfit dislocation networks in theγ∕γ′phase interface of a Ni-based single-crystal superalloy: Molecular dynamics simulations

Abstract

The structure of the $\gamma ∕{\gamma }^{\prime }$ phase interface in a Ni-based single-crystal superalloy is simulated by molecular dynamics (MD) using an embedded atom method potential. From the calculated results we find that three dislocation network patterns, namely square, rectangle, and equilateral triangle, appear on {100}, {110}, and {111} interphase interface, respectively. The dislocation networks consist of four edge dislocations (⟨011⟩ {100}, $⟨\overline{1}10⟩$ {110}, ⟨001⟩ {110}, and ⟨112⟩ {111}). The energy of the $\gamma ∕{\gamma }^{\prime }$ phase interface for {100}, {110}, and {111} plane is $271\mathrm{mJ}∕{\mathrm{m}}^2$, $240\mathrm{mJ}∕{\mathrm{m}}^2$, and $32\mathrm{mJ}∕{\mathrm{m}}^2$. The side length of network is $166.8\mathrm{\AA }$ for the square, $166.8\mathrm{\AA }$ and $235.8\mathrm{\AA }$ for the rectangle and $166.8\mathrm{\AA }$ for the equilateral triangle. The relationship between the size of network and mismatch is presented quantitatively. The calculated results can be supported by very recent experiments. Based on the MD simulation and the energy analysis we have revealed the basic characteristic of structure on $\gamma ∕{\gamma }^{\prime }$ phase interface. The related mechanism of the stability of the interphase interface is also discussed.