On the mechanism of oxidation of iron-16·4% chromium at high temperature☆

摘要: Abstract The mode of oxidation pure iron-16·4% chromium alloy in air at 1100°C has been studied by thermogravimetric methods, metallography and particularly electron-probe microanalysis. It proved possible to follow detail the processes occurring during development protective scale, stratified nodular growths thick scale. Electron-probe microanalysis scales cross-section plan demonstrates that they are largely Cr 2 O 3 containing small proportions iron oxide. subjacent may be depleted as low 5·3% without apparent transformation scale Fe solid solution rich Fe or 2− x 4 spinel. appears likely failure under present conditions is due lifting cracking, followed rapid alloy, although some cases initial layer inherently non-protective its a higher proportion oxides than usual. Stratified usually develops way nodules which also exhibit internal oxidation. As catastrophic break-through progresses, content inner diluted limiting value 20–25% chromium, outer, virtually pure, oxide layers develop almost entirely eliminated. “Steady-state” now prevail, there only being minor fluctuations compositions various total thickens. contribution study understanding mechanism considered conjunction with previous investigations.