Effect of Chloride ion and Zirconium hydride on thr corrosion and SCC behaviors of functionally graded Zirconium alloy p.683

Effect of chloride ion and zirconium hydride on the corrosion and stress corrosion cracking behaviors of functionally graded zirconium alloy was studied to develop an advanced nuclear cladding tubing. The functionally graded zirconium alloy had composition gradient of niobium, which was prepared with a hot pressing followed by cold deformation. The corrosion rates and potentials decreased with increasing FeCl3 and hydride content. The corrosion potentials before and after hydriding are -4.3 VSHE, 8.8x10-5 Acm-2 and -12.5 VSHE, 3.9x10-4 Acm-2, respectively. The stress corrosion cracking susceptibility decreased with elongation rate, indicating the saturation value at 5x10-7 sec-1. SEM observation showed that brittle fracture with corrosion products and pits were observed on the failed surface of hydrided zirconium alloy, suggesting anodic dissolution occurred during exposure after cracking growth along zirconium hydrides. (author)