Quantitative evaluation of plasticity of a ductile nano-component

The plasticity of a copper nano-component is experimentally evaluated by a cantilever beam specimen in which the component is sandwiched between hard layers: silicon and silicon nitride. The cantilever is monotonically loaded with a diamond indenter so that a bending moment is applied to the Cu component, and the deflection at the free-end of the cantilever is precisely monitored by transmission electron microscope observation. The load–deflection relationship shows a clear non-linearity, which is due to the plastic deformation of the Cu component. Using the experimental results, the plastic property of the ductile Cu component is inversely analyzed by finite element method assuming that the component obeys the Ramberg–Osgood constitutive law. The plastic parameters, σ0 (yield stress), n (hardening exponent) and α (yield offset) are optimally fitted to reproduce the experimentally evaluated load–deflection curve. The resultant parameter set is derived as (σ0, n, α) = (345 MPa, 3.2, 1.25). The Cu nano-component has a much higher yield stress and hardening rate compared to bulk Cu.