Microstructural stability and mechanical properties of advanced FeCrAl alloy cladding after thermal exposure at 800 °C ∼1200 °C

The high-temperature stability of FeCrAl alloy cladding is crucial in a loss-of-coolant accident. For this purpose, microstructural stability and mechanical properties of FeCrAl alloy cladding were investigated during isothermal exposure at 800 °C ∼1200 °C for times to 100 h FeCrAl alloy claddings exhibited thermally stable γ-fiber (<111>//ND) oriented grains. The thermal stability temperatures of grains and Laves precipitates were 1000 °C and 900 °C, respectively. With the increase of exposure temperature and time, Laves precipitates coarsen and dissolved, and grains grew abnormally. The high-temperature microstructural evolution of the cladding was quantitatively analyzed using growth kinetics. When the cladding was exposed to 1100 °C for 10 h, the room temperature tensile strength and elongation decrease from 734 MPa, 40 % to 538 MPa, 21 % respectively. The degraded mechanical properties were attributed to coarse grains, dissolved Laves precipitates and oxidation.