Abstract
Microstructural observations were used as the basis for a discussion of the formation and growth of voids in alumina scales. Reactive-element additions to alloys and alloy desulfurization appear to inhibit the growth of interfacial voids, thus improving scale adhesion. This phenomenon is analyzed in terms of surface energies. In addition, a model is proposed for the formation of large internal voids in α-Al2O3 scales. These voids appear to be too large to form as a result of vacancy coalescence and are more frequently observed in scales not doped with a reactive element. The model is based on a growth mechanism where inward and outward growing ridges at scale grain boundaries eventually seal off and form internal voids.
Original language | English |
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Pages (from-to) | 303-328 |
Number of pages | 26 |
Journal | Oxidation of Metals |
Volume | 48 |
Issue number | 3-4 |
DOIs | |
State | Published - 1997 |