Atom probe tomography of thermally grown oxide scale on FeCrAl

Thermally grown Al2O3 scales formed on a FeCrAl alloy were successfully analyzed using pulsed green laser atom probe tomography. Two types of atom probe tomography specimens, the thin oxide type: a thin Al2O3 layer (< 100 nm) with underlying metal (1 mu m), and the thick oxide type: only with Al2O3 (1 mu m), were prepared and analyzed. It was found that the thin oxide type yields poorer mass resolution due to a combined effect of laser absorption and thermal conduction effects. Application of a relatively low laser energy yields a better mass resolution and increased multiple events, however, more accurate quantification results. Although no other oxide phase than Al2O3 is expected to form, some iron-oxygen and chromium-oxygen molecular ions were recorded at the Al2O3/metal interface due to the large change in evaporation field over this zone. (C) 2013 Elsevier B.V. All rights reserved.