Mechanical properties of neutron-irradiated and un-irradiated Zr-Nb alloys: Experiments and damage-involved crystal plasticity modeling

Abstract

Zirconium alloys are widely used in current nuclear reactors, and their components and fabrication process are continuously optimized to enhance accident tolerance. It is imperative to combine experimental research with advanced modeling to study the mechanical properties of un-irradiated and neutron-irradiated new-type zirconium alloys. In this study, Zr-1Nb and Zr-2Nb alloys are irradiated under different fast neutron fluences. Uniaxial tensile tests are conducted on both neutron-irradiated and un-irradiated specimens at room temperature and 380 °C. Irradiation hardening and embrittlement are observed in the macroscale stress-strain curves. A new damage-involved crystal plasticity model is proposed and numerically implemented, considering the effects of irradiation doses, temperature, alloy compositions, and microstructure. The predicted mechanical responses have a good agreement with the current experimental data and the reported values in the literatures, validating the new crystal plasticity model and computational method. The contributions from solution hardening, precipitate hardening, irradiation hardening, and grain boundary hardening to macroscale yield strength are discussed. It is found that the prismatic <a> and pyramidal <c+a> slips are the dominant plastic deformation mechanisms. This study has provided valuable experimental data on neutron-irradiated Zr-Nb alloys and offers a feasible damage-involved crystal plasticity modeling method to capture their mechanical responses, contributing to the development of advanced Zr-xNb alloys.