Cheng Yu Hsieh

US Patent:

54766338, Dec 19, 1995

Filed:

Jul 6, 1994

Appl. No.:

8/273511

Inventors:

Witold M. Sokolowski - Arcadia CA
Marc S. Lane - La Crescenta CA
Cheng H. Hsieh - Hacienda Heights CA
Timothy P. O'Donnell - Sierra Madre CA

Assignee:

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

International Classification:

B22F 300

US Classification:

419 57

Abstract:

An INVAR 36 material having long-term dimensional stability is produced by sintering a blend of powders of nickel and iron under pressure in an inert atmosphere to form an alloy containing less than 0. 01 parts of carbon and less than 0. 1 part aggregate and preferably 0. 01 part individually of Mn, Si, P, S, and Al impurities. The sintered alloy is heat treated and slowly and uniformly cooled to form a material having a coefficient of thermal expansion of less than 1 ppm/. degree. C. and a temporal stability of less than 1 ppm/year.