This paper reports a new approach to lowering the temperature necessary for the preparation of α-Al2O3. Oxidation of Al–Cr alloys, with Cr contents of 18, 23 and 27 %, was performed at temperatures ranging from 620 to 720 °C in air for 100 h. The resulting oxide films were analyzed by SEM, EDS, XRD and XPS. The results showed that α-Al2O3 films were obtained following oxidation of the 18 and 23 wt% Cr alloy samples at 720 °C and that rough surfaces were conducive to the formation of α-Al2O3 such that peened surface samples showed significant α-Al2O3 growth while polished samples showed no oxide by XRD. A 23 wt% Cr sample with a roughened surface exhibited the formation of α-Al2O3 at a temperature of 670 °C. Conversely, only a very thin oxide film was observed on a 27 wt% Cr sample after oxidation at 720 °C.
α-Al2O3Al–Cr alloy Thermal oxidization Low temperature
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This research was supported by the Open Foundation of Key Laboratory for Science and Technology on Surface Physics and Chemistry, China (Grant No. SPC201101).
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