Relations of Microstructural Attributes and Strength-Ductility of Zirconium Alloys with Hydrides

Abstract

Abstract As the first safety barrier of nuclear reactors, zirconium alloy cladding tubes have attracted extensive attention because of its good mechanical properties. The strength and ductility of zirconium alloy are of great significance to the service process of cladding tubes, while brittle hydrides precipitate and thus deteriorate the overall performance. Based on the cohesive finite element method, the effects of cohesive strength, interfacial characteristics, and hydrides geometric characteristics on the strength and ductility of two-phase material (zirconium alloy with hydrides) are numerically simulated. The results show that the fracture behavior is significantly affected by the cohesive strength and that the overall strength and ductility are sensitive to the cohesive strength of the zirconium alloy. Furthermore, the interface is revealed to have prominent effects on the overall fracture behavior. When the cohesive strength and fracture energy of the interface are higher than those of the hydride phase, fracture initiates in the hydrides, which is consistent with the experimental phenomena. In addition, it is found that the number density and arrangement of hydrides play important roles in the overall strength and ductility. Our simulation provides theoretical support for the performance analysis of hydrogenated zirconium alloys during nuclear reactor operation.

Keywords

• Zirconium alloy
• Hydride
• Strength and ductility
• Cohesive finite element method
• Microcrack initiation and propagation