A model to evaluate the radiation-hardening in shallow ion-irradiated metallic materials

In this study, we propose a model to assess the nanoindentation hardness of shallow ion -irradiated materials. The new model is built upon two factors: 1) the contribution of the damage layer to indentation size effect (ISE) becomes negligible when the indentation depth surpasses a certain value; 2) the difference in the profile of the hardness between non- and ion -irradiation samples can still be approximated as a coated system. Compared the fitting results from the Nix-Gao, Korsunsky, modified NGK, and the new model, it reveals that without introducing additional parameters (while maintaining the three degrees of freedom of the Korsunsky model), the new model effectively describes the shallow ion irradiation hardness data of various materials. Furthermore, it addresses the fitting failures and improper convergence observed in other models, enhancing the overall accuracy of the analysis.