An analytical model for oblique cross section nanoindentation of ion-irradiated metallic alloys based on studies of oxide dispersion strengthened steel MA957

Herein, oblique cross section (OCS) nanoindentation is used to measure the hardness changes in He${}^{2+}$ ion-irradiated oxide dispersion strengthened (ODS) steel MA957, to obtain the hardness profile through the thickness, and correlate it with the damage dose profile. Following this, the dispersed barrier hardening (DBH) model is implemented to calculate the hardness of each layer of the irradiated material, based on the displacement damage and He concentration from simulations. Next, a simplified analytical model for the measured hardness at different depths is developed with the assumption that the plastic zone under the indenter is hemispherical and the hardness measured at any given depth depends on the average hardness of the plastic zone volume. This analytical model is implemented with the help of a program written in MATLAB. The calculated hardness profile is compared with the experimental profile, and it is found to be in reasonably good agreement for different energies of the irradiating He ions. This model can be used not only for ion-irradiated materials with varying doses in different layers but also for other metallic materials with surface layers having diffuse interfaces. (© 2021 Wiley-VCH GmbH)