Improving Corrosion Resistance of Zircaloy-4 via High-Current Pulsed Electron Beam Surface Irradiation

Abstract

Zircaloy-4 is extensively used in nuclear reactors as fuel element cladding and core structural material. However, the safety concerns post-Fukushima underscore the need for further enhancing its high-temperature and high-pressure water-side corrosion resistance. Therefore, this study aimed to investigate the effects of high-current pulsed electron beam (HCPEB) irradiation on the microstructures and corrosion resistance of Zircaloy-4, with the goal of improving its performance in nuclear applications. Results showed that after irradiation, the cross-section of the sample could be divided into three distinct layers: the outermost melted layer (approximately 4.80 μm), the intermediate heat-affected zone, and the bottom normal matrix. Large numbers of twin martensites were induced within the melted layer, which became finer with increasing irradiation times. Additionally, plenty of ultrafine/nanoscale grains were observed on the surface of the sample pulsed 25 times. Zr(Fe, Cr)2 second-phase particles (SPPs) were dissolved throughout the modified layer and Fe and Cr elements were uniformly distributed under the action of HCPEB. As a result, the corrosion resistance of the sample pulsed 25 times was significantly improved compared to the initial one. Research results confirmed that HCPEB irradiation is an effective method in improving the service life of Zircaloy-4 under extreme environmental conditions.