Nanoindentation techniques for the microstructure vs. mechanical property correlation of virgin and irradiated materials

Charged particle irradiation can serve as a tool for the emulation of neutron irradiation damage, as damage levels can be attained at a fraction of the irradiation duration and cost. It is a method of choice for the rapid screening of the irradiation tolerance of materials as a precursor of more expensive neutron irradiation studies for nuclear reactor safety. Ion irradiation, however, has only micrometric penetration depths, requiring micro- or nanomechanical methods for the assessment of irradiation induced damage and material hardening, as compared to the macroscopic effects induced by neutron irradiation.

Instrumented indentation techniques are useful to probe the nanomechanical properties and to fingerprint microstructural features of materials. Nanoindentation is sensitive to radiation-induced microstructural changes, irradiation damage and concomitant hardening, thereby facilitating the use of ion irradiation studies to emulate neutron irradiation.

However, there are various ion vs. neutron transferability issues relating to differences in the damage processes, to the practical implementation of ion irradiation experiments, as well as to the nanoindentation method itself. The presentation focuses on benefits and limitations of different nanoindentation techniques enabling the assessment of ion-irradiation damage, such as the separation of the indentation size effect from the effect of ion irradiation under test, and the link between the nanoindentation response and the mechanical properties of interest.

The presentation capitalises on research completed by the “Multiscale Modelling for Fusion and Fission Materials” (M4F) project consortium in the dedicated "Nanoindentation" work package to which NCBJ contributed. The results to be presented help promote the use of ion irradiation for the emulation of material performance and degradation by neutron irradiation damage. This can accelerate the development of radiation tolerant materials for safe nuclear fission and fusion applications.