Effect of Hf on Microstructure and Property of ODS-FeCrAl Alloy

In order to study the effect of a small amount of Hf on the microstructure and property of ODSFeCrAl alloy, two kinds of 14CrODSFeCrAl alloys were prepared by mechanical alloying and subsequent hot isostatic pressing. The microstructure, mechanical property, air oxidation resistance at 1 200 ℃ and steam corrosion resistance at 1 200 ℃ were tested. TEM results show that the oxide precipitate phases of YAlO3 oxide in the two kinds of alloys are fine and dispersed, while the addition of Hf promotes the formation of Y2Hf2O7 nanooxide with finer particle size in the alloy matrix. Due to the Orowan strengthening mechanism, the two kinds of alloys have excellent mechanical property at room temperature and high temperature. The results of XRD and SEM show that the surface of the two kinds of alloys form uniform and dense αAl2O3 film after air oxidation at 1 200 ℃ and steam corrosion at 1 200 ℃, which protects the alloy. The addition of Hf is beneficial to form more uniform αAl2O3 films under the condition of 1 200 ℃ steam corrosion, to inhibit the outward diffusion of Al3+, and to avoid the formation of cavities at the internal grain boundary of the alloy.