Thej oxidation of three Ag-Cr alloys with a nominal content of 17,35 and 69 wt /100 Cr prepared by powder metaurgy has been studied in1 atm of pure O_2 at 700 and 800 deg C. As a consequence of theirtwo-phase nature, these aloys form composite scales containingcomplex mixtures of chromia, a double Ag-Cr oxide and silver metal.The alloys more dilute in chromium undergo a complex internaloxidation of chromium associated with the formaiton of a layer ofsilver metal on top of the scae. The large chromium particle sin theregion of internal oxidation are not completely oxidized due to theslow rate of chromia growht. A continuous layer of hromia forms onyon the alloy containing 69 wt/100 Cr, but it is surmounted by anexternal layer of the double oxide. The intrnal oxidation of chromiumis suppressed in this aoy, which corrodes signficantly more slowlythan those morel dilute in chromiujm.
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