Modification and Control of Oxide Structure on Metals and Alloys: (Phase V)
Final technical rept. 2 Mar 1974-2 Mar 1975
WESTINGHOUSE ASTRONUCLEAR LAB PITTSBURGH PA
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An indepth analyses of over 50 x-ray diffraction patterns of oxides grown on niobium based oxidation resistant alloys are presented. The oxides analyzed were grown in air on niobium based alloys containing Cr, Ti, Al, Co, Ni, andor Fe in various amounts and compositions at temperatures between 800 and 1200C. The analysis of the x-ray diffraction data has shown the oxidation protection of these alloys to be associated with a rutile tetragonal oxide of the form MNbO4 where M Al, Cr, Fe, andor Co. In most of the oxidation resistant alloys, a spinel related structure such as CoAl2O4CoO-Al2O3 was detected. Various powder metallurgy and thermomechanical processing techniques were used to attempt to fabricate useful alloys with the compositions 73.4Nb- 15Fe-11.6Al and 80Nb-5.6Co-13.9Al. Both alloy compositions were processed by various powder metallurgy techniques from elemental, intermetallic, and arc- melted alloy powders. Powder compacts were densified by a combination of cold isostatic pressing and sintering, high impact rate extrusion or conventional extrusion.
- Physical Chemistry
- Metallurgy and Metallography