Accession Number : AD0785261

Title :   Modification and Control of Oxide Structures on Metals and Alloys: (Phase IV).

Descriptive Note : Final rept. 2 Mar 73-2 Mar 74,


Personal Author(s) : Svedberg,Robert C.

Report Date : MAY 1974

Pagination or Media Count : 161

Abstract : Nb-Co-Al and Nb-Fe-Al base alloys have been studied to determine the effects of composition both elemental and constituent (i.e., intermetallic alloy compounds used to make alloys) on the oxides formed during 1200C oxidation in air. Alloys were formed by both pressing and sintering of intermetallic compounds and elemental powders and by arc melting alloy buttons from intermetallic compounds and elements in powder form. Oxidation kinetics have been measured, and the oxides formed have been examined by x-ray diffraction techniques. In addition, Y and Y2O3 additions were made to several alloys to evaluate the effects of rare earth additions on the oxide structure. In addition to the oxidation kinetics and oxide structure correlation, metallographic techniques were used to evaluate the depth of penetration of oxygen into the various alloys. This study confirmed that rutile type oxides such as NbAlO4, NbFeO4, and NbCrO4 are responsible for improved oxidation performance. Parabolic rate constants were measured for these alloys. (Modified author abstract)

Descriptors :   *Oxidation, *Niobium alloys, Oxides, Reaction kinetics, High temperature, Cobalt alloys, Aluminum alloys, Iron alloys, Rare earth elements, Intermetallic compounds, Phase transformations, Crystal structure, Niobium compounds, Aluminates, Chromates, Ferrates

Subject Categories : Physical Chemistry
      Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE