Experiments, characterizations and analysis of a U3Si2–Al dispersion fuel plate with sandwich structure

The mixed U3Si2–Al fuel is a recently developed dispersion fuel structural material adopted in research reactors. The processing method affects strongly the mechanical properties of the dispersion fuel plate, especially, the fatigue properties, which are of great significance for the reliability and performance of fuel elements in most reactors. The fatigue cracks initiation and propagation processes of the U3Si2–Al dispersion fuel plate with sandwich structure were studied in the present paper by in situ SEM observation. The factors influencing fatigue cracks were analyzed, and the nucleation mechanism was proposed. These results indicated that the fatigue crack originated at the vicinal meat edges and propagated primarily along the fuel meat before fracture. The observed fatigue behaviors can be well described by two fracture modes, namely the Mode I and the mixed mode I–II.