Title: Internal nitridation of cobalt-base superalloys

Abstract: A method of internally nitriding and thereby strengthening cobalt-base superalloys having at least 33% cobalt, up to 0.15% carbon, no more than 25% nickel and from 1 to 3% of nitride forming elements from the group consisting of titanium, vanadium, niobium, tantalum and zirconium. The method comprises the steps of: heating the cobalt-base alloy at a temperature of from 1600.degree. to 2500.degree. F in a nitrogen-bearing atmosphere substantially free of moisture and oxygen, and diffusing nitrogen from said atmosphere into and throughout said alloy for a period of time sufficient to form nitrides having an interparticle spacing of less than 10 microns.

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Inventors: Hartline, III, Albert G. (Woodland Hills, CA, US)
Kindlimann, Lynn E. (Woodland Hills, CA, US)

Application Number: 689402
Filing Date: 1976-05-24
Publication_date: 1977-08-23
Assignee: Allegheny Ludlum Industries, Inc. (Pittsburgh, PA)
Primary Class(es): 148/207 148/425, 148/442, 420/439, 420/586
Other Classes:
US Patent Ref:

3432294	Mar, 1969	Wheaton	75/171.
3642546	Feb, 1972	Van Thyne et al.	148/20.
3804678	Apr, 1974	Kindlimann	148/38.

Other Refs:
Primary Examiner: Satterfield, Walter R.
Assistant Examiner:
Attorney: Gioia; Vincent G., Dropkin; Robert F.