Effect of irradiation damage on the shear strength of Cu–Nb interfaces

The influence of irradiation-induced damage on the interfacial shear strength of Cu–Nb interfaces was characterized via compression of nanolaminate pillars performed in situ in a transmission electron microscope. Chemical mixing and interfacial roughening during MeV Kr ion irradiation leads to increased interfacial shear strength by as much as 60%, from 0.6 GPa for the as-deposited material to 0.95 GPa for samples irradiated at liquid nitrogen temperature. The increase in interfacial shear strength was most pronounced at low temperatures (∼−196 °C), but it is still significant at ∼300 °C. This observation was correlated with increased chemical mixing at lower temperatures, as determined from compositional profiles characterized by energy-dispersive spectroscopy.