Corrosion of Aluminum-Uranium Alloys in Water Vapor at 200\260C. PDF Download

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Coupons of aluminum-uranium alloys at 10 and 18 weight percent were exposed to a saturated water vapor condition at 200 degrees C up to about 1500 hours and compared to previous results for aluminum 1100. The aluminum-uranium materials exhibited a range of initial corrosion rates and approached similar rates with the formation of a passive film of boehmite (Al2O3oH2O). The cast and extruded 10 percent uranium, having a primary aluminum-eutectic microstructure, was more corrosion resistant than the 18% cast and extruded. The initial corrosion rates of the aluminum-uranium materials were one to four times higher than that for aluminum 1100. It is postulated that a micro-galvanic coupling between the large UAl4 particles and the aluminum matrix has caused the variation. Sectioning the exposed specimens shows different characteristics of the oxide layers. In the case of the cast and extruded Al-10 percent U alloy, small uranium aluminide particles can be seen in the boehmite matrix and do not seem to be corroded. The oxide film of the Al-18 percent U alloy appears to have two distinct oxide layers. The outer layer has mass aggregates formed in the aluminum oxide matrix, while the inner layer contains UAl4 particles as in the case of Al-10 percent U.