Interface Structure and Radiation Damage Resistance in Cu-Nb Multilayer Nanocomposites

We use atomistic simulations to show that upon removal or insertion of atoms, misfit dislocations in Cu-Nb interfaces shift between two adjacent planes, forming pairs of extended jogs. Different jog combinations give rise to interface structures with unlike densities but nearly degenerate energies, making Cu-Nb interfaces virtually inexhaustible sinks for radiation-induced point defects and catalysts for efficient Frenkel pair recombination.

Figure 1

Set 1 misfit dislocations lie in (a) the Cu-Nb plane in ${\mathrm{KS}}_1$, (b) the $\mathrm{Cu}\mathrm{\text{−}}{\mathrm{Cu}}^{\alpha }$ plane in ${\mathrm{KS}}_2$, and (c) weave between these two planes in ${\mathrm{KS}}_{\min }$. Set 2 misfit dislocations lie in the Cu-Nb plane in all three interface configurations. The relative arrangement of misfit dislocations in these interfaces is illustrated in the schematics above the legend.

Figure 2

Extended jog pair formation in the ${\mathrm{KS}}_1$ interfacial Cu plane upon atom (a),(b) removal and (c),(d) insertion.

Figure 3

The mechanisms of the reconstruction of point defects into jog pairs (see text).

Figure 4

Interface energy ${\gamma }_{\mathrm{Cu}\mathrm{\text{−}}\mathrm{Nb}}$ ($\mathrm{eV}/{\AA }^2$) dependence on areal density ${\rho }_{\mathrm{Cu}}$ ($\mathrm{atoms}/{\AA }^2$) of interfacial Cu compared to Cu vacancy $\Delta E_f^v$ and interstitial $\Delta E_f^i$ formation energies.