The influence of aluminum content on oxidation resistance of new-generation ODS alloy at 1200°c

Abstract

The aim of the paper is to evaluate the effect of aluminum content on the oxidation resistance of new-generation of oxide dispersion strengthened (ODS) alloy at 1200◦C. Three grades of the alloy of chemical composition Fe-15Cr-xAl-4Y2O3 with different Al contents x = 0.3 wt.%, 2.0 wt.% and 5.5 wt.% are prepared by mechanical alloying. The alloys are consolidated by high temperature rolling followed by heat treatment. To study the oxidation resistance the samples are isothermally aged in the air for 1 h, 4 h, 16 h and 64 h at 1200◦C. The oxidation kinetics, composition and formation mechanism of the oxide layers are analyzed. The weight gain of prepared steels is estimated. The kinetics of oxidation is studied on metallographic cross-sections of the exposed samples by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) analysis. The oxides on the surfaces are identified by X-ray diffraction (XRD) analysis. The Al content significantly enhances the oxidation resistance of the alloy. For a sufficiently high Al content in the alloy a compact oxide layer of α-Al2O3 on the surface is formed, which significantly suppresses further oxidation process.