Plastic flow localisation and Nanoindentation
Coordinated by Ermile Gaganidze, KIT (DE)
and David Rodney, CNRS (FR)
The aim of Domain 2 is to develop physically-based models able to predict the mechanical behaviour of irradiated F/M steels, specifically the effects of slip localisation after "low temperature" irradiation, as a consequence of the microstructural changes studied in Domain 1. A multiscale approach is adopted throughout the Domains and WP, addressing the plastic behaviour of irradiated F/M steels at the atomic, mesoscopic, crystal and polycrystal scales, using synergistically atomistic, dislocation dynamics, crystal plasticity and continuum mechanics simulations. The domain also includes experimental validation based on mechanical and microstructural characterization of neutron, ion and proton irradiated model alloys and steels. Modelling of nanoindentation process to study irradiation hardening and its impact on plastic flow localization is a one of the particular objectives of the domain.
Domain 2 is organized in three WPs according to physical scales, which have in common the study of materials subject to deformation
WP4: Deformation mechanisms at the grain scale. This WP develops dislocation dynamics models to describe deformation at grain level, accounting for the presence of irradiation defects, including the influence of alloying elements on dislocation glide and on the interaction strength between dislocations and irradiation defects. Simulations are performed at different length and timescales, from the atomic (dislocation cores) to the continuum scale (entire grain). This WP includes four tasks, three devoted to developing models operating at increasingly larger scales and limited experimental content, the fourth one eminently experimental.
WP5: Channelling at the polycrystal scale. This WP investigates channelling at the polycrystalline scale and its impact on the deformation and damage evolution. The main outcome will be the prediction of the post yield-post necking behaviour of irradiated F/M steels by using mean-field and full-field homogenization, finite element crystal plasticity and continuum mechanics modelling tools. The ultimate goal is to develop a model that provides a description of the post-yield/post-necking behaviour of irradiated F/M steels. This WP is organized in four tasks. The first three are devoted to developing models enabling the description of the macroscopic tensile behaviour of irradiated F/M steels and accounting for the cavitation mechanism in the presence of channeling. The fourth task concerns experimental activities for the validation of the models developed in the other three tasks.
WP6: Nanoindentation. This WP models nanoindentation processes of ion-irradiated materials and performs targeted experimental observations with the aim of studying irradiation hardening and understanding the effects of irradiation on the plastic flow. Ion irradiated specimens are characterized by nanoindentation using pyramidal and spherical indenters, which allow probing very shallow depths and thus extracting properties of thin layers. These experiments, together with the support of suitable models, are used to define best practices for the execution of nanoindentation tests on the small thickness within which ion irradiation affects materials.