Method of manufacturing iron aluminide by thermomechanical processing of elemental powders

Patent · Sat Jan 01 04:00:00 EST 2000

OSTI ID:872891

Deevi, Seetharama C ^[1]; Sikka, Vinod K ^[2]; Hajaligol, Mohammed R ^[3]

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1. Midlothian, VA
2. Oak Ridge, TN
3. Richmond, VA

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.

• Research Organization: LOCKHEED MARTIN ENRGY SYST INC
• DOE Contract Number: AC05-84OR21400
• Assignee: Philip Morris Incorporated (New York, NY)
• Patent Number(s): US 6033623
• OSTI ID: 872891
• Country of Publication: United States
• Language: English

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