| 摘要 |
Alloys containing aluminium are characterised by an outstanding oxidation resistance at high temperatures, that is based on, inter alia, the formation of a thick and slow-growing aluminium oxide layer on material surfaces. If the formation of the aluminium oxide layer reduces the aluminium content of the alloy so far that a critical aluminium concentration is not reached, no other protective aluminium oxide layer can be formed. This leads disadvantageously to a very rapid breakaway oxidation, and the destruction of the component. This effect is stronger at temperatures above 800° C. due to the fact that, often at this point, metastable Al2O3 modifications, especially &thetas;- or γ-Al2O3, are formed instead of α-Al2O3 that is generally formed at high temperatures. The above-mentioned oxide modifications are disadvantageously characterised by significantly higher growth rates. The invention relates to methods whereby aluminium-containing alloys advantageously form an oxidic covering layer predominantly consisting of α-Al2O3, at a temperature higher than 800° C., especially in the initial stage of oxidation, and thus have a significantly improved long-term behaviour.
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