Studies on as-cast microstructure and oxidation behavior of the FeCrBAl alloys at 1073 K. (June 2019) - Ju, Jiang
Abstract: Based on the FeCrB alloy, the Fe12Cr1.5BxAl (x = 0, 2, 4, 6 and 8 wt%) alloys were designed by adding Al. The as-cast microstructure and cyclic oxidation behavior have been investigated extensively in this study. The results reveal that the as-cast microstructure of FeCrB alloy consists of martensite (bcc), retained austenite (orthorhombic) and M2 (B, C)-bct, M7 (C, B)3 -hcp, M23 (C, B)6 -complex fcc boron-carbides, gradually changing to α-(Fe, Al, Cr) solid solution (bcc), M2 (B, C)-bct, M7 (C, B)3 -hcp, M23 (C, B)6 -complex fcc boron-carbides and Fe3 Al intermetallic compound with the increasing of Al contents. The oxidation kinetics of all alloy samples follow a parabolic oxidation kinetic law. The oxidation rate constant k p in Al-free FeCrB alloy is nearly four times of that in FeCrB8Al alloy. The additions of Al refine the grains and make the distribution of elements more uniform, which results in forming a continuous and dense oxide film containing Al2 O3 oxide with excellent fluidity and thermal stability, remarkably enhancing the high temperature oxidation resistance of FeCrBAl alloy. Highlights: Based on FeCrB alloys, a new FeCrBAl alloy was designed. The as-cast microstructure of FeCrBAl alloys was investigated. Cyclic oxidation behavior of the FeCrBAl alloys was studied at 1073 K in air. The oxidation kinetics of the FeCrBAl alloys followed the parabolic-rate law. The FeCrB8Al exhibits the highest oxidation resistance at 1073 K, about four times of FeCrB alloy.