FILM GROWTH ON ALUMINUM IN HIGH-TEMPERATURE WATER

Film growths on aluminum and two aluminum-1 wt.% nickel alloys in water at 250 and 350 deg C were studied. It was found that oxide growth does not advance on a uniform front but, to the contrary, the advancing surface contains many outcrops in the form of thin platelets, chunky outcrops, and whiskers. With both the pure metal and the alloys considerable intergranular attack was observed. The general corrosion product was usually more uniform in crystal size when formed on the pure metal, but variations in crystal size were observed on both aluminum and alloys with varying features of the metal surface. The roughness of the general oxide surface (includlng outcrops) was found to increase rapidly to about 0.2 micron and then remain relatively constant with increasing film thickness. The composition of films formed under all investigated conditions, except one, was found to be boehmite ( alpha -Al/sub 2/O/sub 3/- H/sub 2/O). This exception was films carried by the alloy specimens after testing for 32 days at 350 deg C. In this case the main corrosion film was still boehmite, but in addition the outer surface supported long needles of diaspore ( beta -Al/sub 2/ O/sub 3/- H/sub 2/O). (auth

Fabrication and properties of a tin-lithium alloy.

A Sn-25 at.% Li alloy has been fabricated by starting with pure Sn and Li. The alloy was cast into various shapes and sent to researchers in several organizations in the United States and abroad for property measurements. The fabrication procedure involved gradual addition of Li from a separate vessel into a vessel that contained Sn; continuous stirring of the mixture during Li addition increased the Li content of the alloy gradually from 0 to the final value of 25 at.%. The melting temperature of the alloy was 334 C; its density was 6.36 g/cm{sup 3}. Results are presented on microstructure, chemical composition, phase distribution, and microhardness of the alloy. Several experiments were conducted to evaluate the chemical reactivity of the alloy with air, water, and steam. Results showed that the alloy undergoes catastrophic oxidation when T >250 C in air and develops an oxide scale in water at temperatures up to 95 C. Exposure in low-pressure steam at 200 C caused significant swelling and cracking of the alloy

CORROSION RESISTANCE AND MECHANICAL PROPERTIES OF ALUMINUM POWDER PRODUCTS

Experimental extrusions were prepared from mixtures of atomized aluminum alloy and several powdered additives, including SiO/sub 2/, AlPO/sub 4/, and Al/ sub 2/O/sub 3/. Some of the extrusions failed during corrosion testing in water at 290 and 350 C. Others corroded in approximately the same fashion as wrought X8001 alloy. The ultimate tensile strengths of these extrusions at 316 C were approximately two and one-half times greater than that of wrought X8001 alloy. (auth

CORROSION OF ALUMINUM-URANIUM ALLOYS IN HIGH-TEMPERATURE WATER

Sixty-day corrosion tests were performed in water at 290 deg C with unirradiated aluminum-uranium alloys containing 2 wt.% nickel and 1/2 wt.% iron, with several uranium contents from 15 wt.% to 53 wt.%. The maximum methi penetration rate (4 mils per year by extrapolation) of these alloys was no more than twice that of X8001 alumunum cladding alloy at the same temperature. Preliminary testing in water at 350 deg C indicated good corrosion resistance for this alloy system ap to a maximum of 80 wt.% uranium. (auth