Transition of the Zr(Cr, Fe) intermetallic phase up to the eutectic temperature

共晶温度までのZr(Cr, Fe)金属間化合物相の転移

Mohamad, A. B. ; 根本 義之  ; 古本 健一郎*; 岡田 裕史*; 佐藤 大樹*

Mohamad, A. B.; Nemoto, Yoshiyuki; Furumoto, Kenichiro*; Okada, Yuji*; Sato, Daiki*

The development of Accident Tolerant Fuel (ATF) had been started by conducting the investigation on new concepts to improve the safety of Light Water Reactors (LWRs). It is well known that the Cr coating on Zry cladding has shown an improvement in behavior under accident conditions and normal operation. In the Cr-Zr system, the eutectic phase of ZrCr is present at 1332C and forms as intermetallic compounds. There is still lack of data on the evolution of the intermetallic phase when the oxidation temperature reaches the eutectic temperature of Cr-Zr. Therefore, the purpose of this study will be to understand the solid-to-liquid phase transition of Zr(Cr, Fe). High temperature oxidation tests were performed in a steam atmosphere to the target temperature (i.e., 1100C, 1200C, 1300C, 1350C, and 1400C) for different exposure times of 5, 30, and 60 min. From the tests, the transition of Zr(Cr, Fe) that formed at the Cr-Zr interface and also that precipitated in the Zry cladding were studied with varied oxidation time and temperatures. The microstructural evolution of the intermetallic phase was observed in the Zr substrate within the progress of the oxidation of Cr-coated Zry. A dendritic structure was observed at 1400C, indicating the formation of the Zr(Cr, Fe) liquid phase when the oxidation temperature is above the eutectic temperature.