Evaluation of the depth-dependent yield strength of a nanoindented ion-irradiated Fe–Cr model alloy by using a finite element modeling

Ion bombardment of materials produces a shallow damaged region, in which the density of the radiation-induced defects is highly heterogeneous in depth from the irradiated surface. A nanoindentation on the surface of an ion-irradiated specimen probes the load-depth (L–h) response of the damaged region, which has varying mechanical property along the indentation depth. The measured nano-hardness thus is an average value of a varying hardness over the damaged region. The dose dependence of the increase in yield strength of an ion-irradiated Fe–Cr model alloy was evaluated by combining a nanoindentation test with a finite element (FE) modeling. The radiation damaged region was discretized into a finite number of layers with a pre-defined depth profile of the yield strength in terms of the dose level in the FE modeling. The dose-dependent yield strength and the intrinsic hardness of the damaged regions were extracted by comparing the computed L–h curve with the experimentally measured one.