4.1.1 Nanostructure and micro chemical evolution under irradiation and thermal ageing g : development of phase field models describing microstructure evolution in Fe alloys A. Legris (CNRS/UMET), M. Nastar (CEA) : NEEDS (National funding) proposal H. Zapolsky, O. Kapikranian, C. Pareige, P. Pareige, B. radiguet, C. Domain (EDF) CNRS/GPM Atomic Density Function (ADF) Modelling of Grain Boundaries in the BCC iron Funded by French projects : MAI SN – CARNOT

Principle : - Continuous variable → atomic density function ρ(r) → coarse-graining of atomic trajectories over times exceeding thermal vibration times -Equilibrium state → minimum of a free energy functional taking into account atomic interactions and thermal vibrations - Dynamics → dissipation dynamics equation P. F. Tupper and M. Grant, Phase field crystals as a coarse-graining in time of molecular dynamics, EPL 81 (2008) 40007

ADF GB's structures have been validated by MD simulations with EAM potentials. Simulation of vacancy annihilation have been performed. Efficiency of vacancy annihilation depends on the GB's misorientation. Next step: to introduce P or Cr to simulate GB segregation at equilibrium. ADF vs MD: - Fast access to the equilibrium 3D atomic structure of any GB by crystallization (in MD several thousands of initial conditions have to be tested to find those closer to the equilibrium ones) "Atoms" appear at the positions that minimize the free energy (no additional criteria for atom deletion nor rigid body translations needed, unlike in MD). - Access to big time and space scales Difficulties: - Inability for instance to use directly the EAM potentials in the ADF simulation. Ambiguity in the energy scale choice Coupled with MD simulations with EAM potentials performed on the GB atomic configurations grown by the ADF method, represents most promising tool for systematic modeling of GBs of various geometries.

4.1.1iPost-irradiation characterisation of ion-irradiated Fe-Cr alloys using TEM, PAS and APT APT : Fe-9%Cr 100°C, 300°C, 420°C 1 dpa 300°C 5 dpa Fe-12%Cr 300°C 1 and 5 dpa Irradiation in FZD: Ions: Fe+ Energy: 3 energies: 0.5 MeV, 2 MeV, 5 MeV 2 Doses: 1 dpa and 5 dpa 3 Temperatures: 100°C, 300ºC, 420°C SRIM calculation results

4.1.1lLow-dose neutron and ion irradiation experiments on FeCr and FeCrX alloys, as well as Fe-Cr based steels, and subsequent nano- & micro-structural characterisation (beyond FP7/GETMAT) APT samples will be prepared soon for BR2 irradiations High dose – High flux 300°C Fe-9Cr : 5 Fe-5Cr-NiSiP Fe14Cr-NiSiP 100°C : Fe-9CrNiSiP 450°C : Fe-9CrNiSiP Fe-14CrNiSiP T91 F82H or E97 High flux – low dose 300°C: Fe-9CrNiSiP Fe-14CrNiSiP Low flux – low dose – 300°C : Fe-14CrNiSiP Fe-9CrNiSiP

4.2 : ODS 4.2.3Nanostructure and microchemical evolution under irradiation and thermal ageing 4.2.3aPost-irradiation characterisation of ion-irradiated ODS alloys using TEM and APT (nanostructural evolution, changes in grain boundaries) and micromechanical testing APT work done in the framework of CPR ODYSSEE (French funding) PhD MatISSE project – WP4