The 6th International Conference on Matter and Radiation at Extremes (ICMRE2023)

241 / 2023-04-18 22:02:29

Fracture behaviors of long-term low-dose-rate neutron-irradiated Al-Mg-Si alloy

High Pressure Physics and Materials Science > Functional materials and physics-poster

Here, we report on fracture behaviors of Al-Mg-Si alloys (LT21 Al alloys) decommissioned from a research reactor in service for 30 years. Microscopic characterizations show that the initial microstructures of the long-term low-dose-rate neutron-irradiated LT21 Al are dominated by a large number of micron-sized voids and second-phase particles, different from short-term high-dose-rate neutron-irradiated materials. Quasi-static tensile and shock spall experiments on the irradiated and unirradiated LT21 Al reveal considerable irradiation-induced softening (larger than 40%) in both the tensile and spall strength. We attribute the irradiation softening to the over-aging process promoted by irradiation enhanced diffusion during the long-term service. Postmortem characterizations on shock-recovered samples indicate that the long-term low-dose-rate neutron irradiation-induced microstructures (micron-sized voids and second-phase particles) facilitate nucleation and growth of dynamic damage in irradiated materials, thus playing an important role in change in facture behaviors.