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Method of manufacturing iron aluminide by thermomechanical processing of elemental powders

United States Patent

6,033,623
March 7, 2000
View the Complete Patent at the US Patent & Trademark Office
Oak Ridge National Laboratory - Visit the Partnerships Directorate Website
A powder metallurgical process of preparing iron aluminide useful as electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 20 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1 % rare earth metal, .ltoreq.1% oxygen, and/or .ltoreq.3% Cu. The process includes forming a mixture of aluminum powder and iron powder, shaping the mixture into an article such as by cold rolling the mixture into a sheet, and sintering the article at a temperature sufficient to react the iron and aluminum powders and form iron aluminide. The sintering can be followed by hot or cold rolling to reduce porosity created during the sintering step and optional annealing steps in a vacuum or inert atmosphere.
Deevi; Seetharama C. (Midlothian, VA), Lilly, Jr.; A. Clifton (Chesterfield, VA), Sikka; Vinod K. (Oak Ridge, TN), Hajaligol; Mohammed R. (Richmond, VA)
Philip Morris Incorporated (New York, NY)
08/ 679,341
July 11, 1996
STATEMENT OF GOVERNMENT RIGHTS The United States government has rights in this invention pursuant to contract no. DE-AC05-840R21400 between the United States Department of Energy and Lockheed Martin Energy Research Corporation, Inc.