Experiments and modeling of the macroscale mechanical responses of neutron-irradiated FeCrAl alloys

Abstract

Iron chromium aluminum (FeCrAl) alloys have been regarded as candidate materials for accident-tolerant fuel cladding. In this study, the stress-strain curves of various neutron-irradiated and un-irradiated FeCrAl alloys at the test temperatures of 300 K and 653 K are obtained through the uniaxial tensile tests, with the fast neutron fluences of 2 × 1019 n/cm2 and 8 × 1019 n/cm2 (E ≥ 1 MeV). Simultaneously, improved shear strain rate model and damage evolution model are proposed in the crystal plasticity theoretical frame, with the irradiation effects involved. The developed models are numerically implemented, with the simulation results of the macroscale stress-strain curves agreeing well with the experimental data. The irradiation hardening and embrittlement phenomena are captured, together with the characteristics of strain hardening and softening. The influences of alloy compositions, temperatures, and fast neutron fluences on yield strength, ultimate tensile strength, yield ratio, and uniform elongation are discussed. Macro mechanical properties such as yield strength and yield ratio are found to be near-linearly correlated with crystal plasticity model parameters. A model for multi-objective optimization of the mechanical properties is established, with which the optimum design strategies of alloy composition for the materials in the in-reactor service environments are proposed. This study could provide a theoretical basis for the research and development of advanced FeCrAl alloys.