Published online by Cambridge University Press: 11 February 2011
Detailed finite-element modeling of nanoindentation data is used to obtain the micromechanical properties of Ni implanted with ∼5 at.% He to a depth of 600–700 nm. Properties of He-containing metals have implications for studies of radiation damage and for fundamental issues of dislocation pinning. Cross-section TEM shows the implantation produces a highly damaged layer containing a fine dispersion of He bubbles with diameters of ∼1 nm or smaller, with some evidence for interconnection between bubbles. Nanoindentation of the Ni(He) layers gave a fairly hard, stiff response to depths of 100–120 nm, beyond which the layer failed. By modeling the layer as an isotropic, elastic-plastic solid with the Mises yield criterion, the Ni(He) is shown to have a hardness nearly 7 times that of untreated Ni. However, unlike other treatments that we have used to produce very hard Ni-based layers, the Ni(He) layer fails at relatively modest shear stress levels.