Ion irradiation combined with nanoindentation as a screening test procedure for irradiation hardening

Ion irradiation has long been recognized as a means to efficiently approximate neutron damage in structural materials. Likewise, nanoindentation has long been recognized as a tool to probe the mechanical behaviour of thin layers. The combination of both techniques in order to establish a screening test procedure for irradiation hardening requires consideration of a number of details. The objective is to specify one among several possible variants of such a screening test.
Important constituents of an approach based on ion irradiation and nanoindentation as a screening test procedure for the irradiation response of structural materials exposed to heavy neutron irradiation are: (1) the design of the ion irradiation experiments, e.g. using the MD code SRIM, (2) nanoindentation testing over a large range of indentation depths, (3) elimination of the indentation size effect, elimination of the substrate effect and pile-up correction, (4) careful documentation of the selected options and parameters.
A version of the approach sketched above was applied to unirradiated, ion-irradiated and neutron-irradiated 9%Cr ferritic/martensitic steel T91 (MATTER reference material). The findings indicate that the approach based on ion irradiation and nanoindentation is suitable as a screening test for F/M steels exposed to neutron irradiation.