Thermodynamic modeling and mechanical properties of LOCA simulated Zr-Nb alloy

摘要

LOCA-simulated oxidation and precipitation behavior for Zr-Nb alloy was evaluated by thermodynamic calculation. Zr-Nb-O ternary phase diagrams were evaluated by ThermoCalc and the results were compared to those for Zr-O binary system. The mole fraction and compositions of each phase were calculated, which indicate that a-phase in oxidized Zr-Nb alloy includes higher oxygen content than Zr. Nb-enriched fi-phase includes low oxygen, which causes larger oxygen content fluctuation in Zr-Nb alloy. To confirm the results, indentation hardness and oxygen distribution were investigated for oxidized Zr-1.8Nb and Zry-4 claddings. The experimental results qualitatively agreed with the calculation.