The role of Ta on twinnability in nanocrystalline Cu–Ta alloys

Nanostructured Cu–Ta alloys show promise as high-strength materials in part due to their limited grain growth. In the present study, we elucidate the role of Ta on the transition from deformation twinning to dislocation-mediated slip mechanisms in nanocrystalline Cu through atomistic simulations and transmission electron microscopy characterization. In particular, computed generalized stacking fault energy curves show that as Ta content increases there is a shift from twinning to slip-dominated deformation mechanisms. Furthermore, heterogeneous twinnability from microstructural defects decreases with an increase in Ta. The computed effect of Ta on plasticity is consistent with the HRTEM observations. IMPACT STATEMENT We show for the first time using atomistic simulations and TEM that, similar to grain size, the Tanano-particles can be used to tailor the governing deformation mechanisms in NC-alloys.