Mechanism of neutron irradiation-induced surface crack density changes in Chromium-coated zirconium alloys

This study investigates the effect of irradiation on the crack density of chromium-coated zirconium alloys. Based on the continuum mechanics framework, irradiation damage is described through changes in the stress-strain curve. A fracture prediction method for chromium coatings is established using a strength theory and the birth and death element method, showing good agreement with experimental trends. The study shows that with increasing irradiation dose, the substrate material undergoes irradiation-induced embrittlement, leading to a significant increase in interfacial shear stress. As a result, the initial cracking strain decreases from approximately 0.414 % to 0.408 %, the saturated crack density increases by about 36.4 %, and the crack opening displacement decreases by around 36.6 %. For coating thickness, a thicker coating leads to a lower saturated crack density. When the substrate thickness exceeds the critical value, it no longer affects the saturated crack density. The residual stress in the coating does not affect the saturated crack density but only influences the crack initiation strain. This study provides theoretical support for the irradiation-resistant design of accident-tolerant fuel cladding coatings.