Internal stresses and textures of nanostructured alumina scales growing on polycrystalline Fe₃Al alloy

Abstract

The evolution of internal stresses in oxide scales growing on polycrystalline Fe 3 Al alloy in atmospheric air at 700°C was determined using in situ energy-dispersive synchrotron X-ray diffraction. Ex situ texture analyses were performed after 5 h of oxidation at 700°C. Under these conditions, the oxide-scale thickness, as determined by X-ray photoelectron spectroscopy, lies between 80 and 100 nm. The main phase present in the oxide scales is ␣-Al 2 O 3 , with minor quantities of metastable -Al 2 O 3 detected in the first minutes of oxidation, as well as ␣-Fe 2 O 3 . ␣-Al 2 O 3 grows with a weak ͑0001͒ fiber texture in the normal direction. During the initial stages of oxidation the scale develops, increasing levels of compressive stresses which later evolve to a steady state condition situated around Ϫ300 MPa.

Archives of Foundry Engineering

“…2 and 3, respectively (as revealed by OM). Coarse grains can be noticed for the two alloys (average grain diameter of 406,7µm to Fe-25Al and 322µm to Fe-11Alalloy) and presence of numerous precipitates with acicular morphology, typical of κ-type carbides dispersed in interior of grains and in grain boundaries [10]. A closer view of the κ-carbides is presented in Fig.…”