Nanoindentation applied to ion-irradiated and neutron-irradiated Fe-9Cr and Fe-9Cr-NiSiP model alloys

Nanoindentation of ion-irradiated materials has attracted much interest as a tool envisaged to derive the dose dependence of bulk-equivalent hardness from small samples. A major challenge arises from the steep damage gradient in the thin ion-irradiated layer and its unavoidable interplay with the indentation size effect. The present study relies on a number of choices aimed at simplifying the interpretation of the results and strengthening the conclusions. The studied alloys are two ferritic Fe-9Cr model alloys differing in controlled amounts of Ni, Si, and P known to enhance irradiation hardening. Both ion-irradiated (5 MeV Fe2+ ions) and neutron-irradiated samples along with the unirradiated references were investigated using Berkovich tips. According to the collaborative nature of the study, tests were conducted in two different laboratories using different equipment. A generalized Nix–Gao approach was applied to derive the bulk-equivalent hardness and characteristic length scale parameters for the homogeneous unirradiated and neutron-irradiated samples. Comparison with Vickers hardness indicates a 6% overestimation of the bulk-equivalent hardness as compared to the ideal correlation. For the case of ion irradiation, a first model assumes a homogeneous irradiated layer on a homogeneous substrate, while a second model explicitly takes into account the damage gradient. The first model was combined with both the original and the generalized Nix–Gao relation.

BERGNER Frank;  KADEN C.;  DAS Aniruddh;  MERINO Susana;  DE DIEGO Gonzalo;  HAEHNER Peter; 

2022-08-08

AIP PUBLISHING

JRC129498

0021-8979 (online),   

https://aip.scitation.org/doi/10.1063/5.0098807,    https://publications.jrc.ec.europa.eu/repository/handle/JRC129498,   

10.1063/5.0098807 (online),