Early-stage corrosion behavior of Al-based Gd2O3–W shielding composites in a simulated spent fuel wet storage environment

Abstract

The early-stage corrosion behavior of the newly fabricated Al-based Gd2O3–W composites was investigated in the boron-lithium water at 40 °C to simulate the environment of spent fuel wet storage. The exposed Al matrix was first corroded, which induced the increase of the weight and corrosion resistance. Subsequently, the pitting occurred and then destroyed oxide film, slowing down the increase of the weight and decreasing corrosion resistance. Meanwhile, the pitting initiated only in the Al regions but was inhibited by strengthening particles. The oxide film structure was only one layer on the particles, but two layers on the Al matrix. Meanwhile, a diffusion layer was observed under the corrosion layer. The sintering products such as Al3Gd and Gd3Al5O12 had higher corrosion resistance than Al matrix and were hardly corroded. 400 keV Fe + irradiation induced the amorphization of the Al phase and caused the formation of irradiation defects that provided a fast channel for oxidizing species and accelerated the corrosion process. The corrosion potential of the samples sintered with higher temperature and longer time was low. The impedance of the sample increased with the increase of sintering degree but decreased when the samples were pre-irradiated.