Heat treated superalloy single crystal article and process
AssigneeUnited Technologies Corporation
InventorsDavid N. Duhl, Walter E. Olson
Life of this patent
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Abstract
Nickel base superalloy single crystal articles formed of a particular compositon and heat treated are described as is the process employed. The resultant articles are substantially free from the grain boundary strengtheners such as carbon, boron, and zirconium and contain only a limited amount of cobalt. As a result of the alloy composition, the alloys have a high incipient melting temperature. The heat treatment process homogenizes the micro-structure, and refines the gamma prime morphology.
Claims9
A heat treated nickel base single crystal superalloy article suited for use at elevated temperatures having a composition consisting essentially of:
- a. from about 8 to about 12% chromium,
- b. from about 4.5 to about 5.5% aluminum,
- c. from about 1 to about 2% titanium,
- d. from about 3 to about 5% tungsten,
- e. from about 10 to about 14% tantalum,
- f. from about 3 to about 7% cobalt,
- g. balance essentially nickel, said article being free from intentional additions of carbon, boron and zirconium, and said article being free from internal grain boundaries and having an average gamma prime particle size of less than about 0.5 micron and an incipient melting temperature in excess of about 2350.degree. F.
A method for producing a single crystal nickel base superalloy article suited for use at elevated temperatures including the steps of:
- a. providing an alloy consisting essentially of from about 8 to about 12% chromium, from about 4.5 to about 5.5% aluminum, from about 1 to about 2% titanium, from about 3 to about 5% tungsten, from about 10 to about 14% tantalum, from about 3 to about 7% cobalt, balance essentially nickel, said alloy being free from intential additions of carbon, boron and zirconium,
- b. forming the alloy into a single crystal article, and
- c. solution heat treating the article at a temperature of from about 2350.degree. to about 2400.degree. F., but below the incipient melting temperature so as to place the gamma prime phase into solid solution, and
- d. aging the article at a temperature of from about 1600.degree. to about 2000.degree. F. to reprecipitate the gamma phase in a refined form.
An intermediate single crystal article useful in the production of articles for use at elevated temperatures, said intermediate article having a composition consisting essentially of:
- a. from about 8 to about 12% chromium,
- b. from about 4.5 to about 5.5% aluminum,
- c. from about 1 to about 2% titanium,
- d. from about 3 to about 5% tungsten,
- e. from about 10 to about 14% tantalum,
- f. from about 3 to about 7% cobalt,
- g. balance essentially nickel, said article being free from intentional additions of carbon, boron and zirconium, said article being free from internal grain boundaries and having an as cast microstructure and having an incipient melting temperature in excess of 2350.degree. F.
Dependencies are inferred from the claim text.