Preparation And Properties Of FeCrAl Accident-Tolerant Fuel Cladding

FeCrAl alloy is the leading accident-tolerant fuel caladding candidate for light water reactor application because of its excellent high temperature oxidation resistance,mechanical properties,processing properties,creep resistance,and radiation swelling tolerance.Three kinds of alloys,FeCrAl,FeCrAlY and FeCrAlYTi,were produced to study the effects of Y and Ti on mechanical properties and high temperature oxidation resistance.The following main conclusion were obtained:(1)Optical microscope and EBSD analysis showed that the addition of Y element refines the grain,and the additions of Y and Ti elements further refine the grain.Microhardness test exhibits that the additions of Y and Ti increases the hardness of FeCrAl alloys.(2)The tensile strength and elongation at room temperature are improved by adding Y element.The additions of Y and Ti further improve the tensile strength,but the elongation decreases.The tensile strength of the three alloys is similar at 300?,the elongation of FeCrAlY>FeCrAlYTi>FeCrAl.The tensile strength of three alloys is similar at 600?,the elongation of FeCrAl>FeCrAlY>FeCrAlYTi.The fracture surfaces of the three alloys show obvious dimples at room temperature and high temperature,indicating ductile fracture.(3)The weight gain curves of three kinds of alloys oxidized in air at 1200? for 110 h showed that the oxidation-weight curves of the three alloys accord with the parabolic oxidation law.The results showed that the oxidation resistance of the three alloys is FeCrAlYTi>FeCrAlY>FeCrAl.XRD analysis showed that the oxidation films of the three alloys are composed of ?-Al2O3 and FeCr.(4)Morphology and composition analysis of the oxide films showed that,in the FeCrAl alloy,the obvious cracking and peeling of oxide films are observed.The oxide film has a large number of voids.The oxide film is uneven,and is mainly composed of Al2O3.In FeCrAlY alloy,oxide film is more compact compared to FeCrAl alloy.Y element can improve the adhesion of the oxide film,and significantly improve the morphology of oxide film.The oxide film mainly is Al2O3.The oxide film morphology of FeCrAlYTi alloy is similar to that of FeCrAlY alloy after oxidation at high temperature.The oxide film is compact and intact.The effect of Ti element on the oxide film is very small,and the oxide film component is also Al2O3.(5)The morphology and composition analysis of the oxide layer shows that the thickness of the oxide layer of FeCrAl alloy fluctuates greatly,and the oxide layer is wrinkled and not smooth.The oxide layers of FeCrAlY and FeCrAlYTi alloys are very thin.the overall oxide layers are smooth and dense.In FeCrAl alloy,the oxide layer is mainly composed of Al2O3 and FeCr near the alloy matrix.The oxidation layer of FeCrAlY alloy is composed of Al2O3.The Y element is mainly distributed in the band-like region.The FeCrAlYTi alloy has the similar oxide componet as the FeCrAlY alloy.Ti element does not be observed in the oxide layer.