The paper describes an examination of the effect of the addition of zirconium as a third
element on the heat-resisting properties and explains the high temperature oxidation mechanism of
Fe3Al intermetallic compounds. The Fe3Al and Fe3Al-0,05Zr specimens have been isothermally
oxidized in the temperature range of 1173-1473 K in synthetic air for 100 hrs. The formed oxide layer,
about 1,5-2 μm thick, was Al2O3. An examination of the cross-sectioned scales by SEM-EDS showed
that the alumina layer consisted of a small inner columnar layer and an outer equiaxed grain layer.
Additionally, very fine (50-150 nm) oxide grains rich in Zr, further identified as ZrO2, were found
across the alumina scales. To understand the role of Zr on the growth mechanism of α–Al2O3 oxide
scale on Fe3Al materials, two-stage oxidation experiments were performed (16O2/18O2), followed by
SIMS and TEM-SAD observations. Particular attention was paid to the use of TEM in order to
precisely characterize the products on samples prepared using the FIB (Focused Ion Beam) method. A
combination of analytical techniques revealed that ZrO2 particles, most of which were formed along
alumina grain boundaries, enhanced oxygen diffusion along grain boundaries due to oxygen-deficient
composition of zirconium oxide (ZrO2-y).
