Heat treated superalloy single crystal article and process

Claim 1

A single crystal nickel base superalloy article free from intentional additions of cobalt, carbon, boron, and zirconium, consisting essentially of from about 5 to about 18% chromium, at least 5% of an element chosen from the group consisting of from 2 to 8% aluminum and from 1 to 5% titanium and mixtures thereof; at least 5% of an element chosen from the group consisting of up to 10% molybdenum, up to 15% tungsten, up to 12% tantalum, up to 3% columbium, up to 3.5% hafnium, up to 7% rhenium, and mixtures thereof; balance essentially nickel; said single crystal article having a homogeneous microstructure which contains gamma prime particles having a size of less than 0.5 microns, and said microstructure being free of MC type carbides, and TCP phases.

Claim 8

A method for producing nickel base superalloy single crystal articles which have a homogeneous microstructure and in which the gamma prime phase presents a refined morphology, including the steps of: a. providing a mass of nickel base superalloy material which is free from intentional additions of a cobalt, carbon, boron, and zirconium; and which consists essentially of from about 5 to 18% chromium; at least 5% of an element chosen from the group consisting of from 2 to 8% aluminum and from 1 to 5% titanium and mixture thereof; at least 5% of an element chosen from the group consisting of up to 10% molybdenum, up to 15% tungsten, up to 12% tantalum, up to 3% columbium, up to 3.5% hafnium, up to 7% rhenium, and mixtures thereof; balance essentially nickel, b. melting the nickel base superalloy and solidifying the alloy under conditions of unidirectional heat flow so as to produce a single crystal article having a microstructure which consists essentially of gamma prime particles in a gamma prime matrix, with the gamma prime particles having a particle size of about 1.5 microns, said article having an incipient melting temperature, in excess of about 2300° F., as a result of the absence of carbon, boron and zirconium, and a gamma prime solvus temperature, which is less than the incipient melting temperature, said microstructure being free of MC type carbides as a result of the absence of carbon and free from TCP phases, as a result of the absence of cobalt, c. heating the article to a temperature greater than the gamma prime solvus temperature and less than the incipient melting temperature for a period of time sufficient to dissolve substantially all of the gamma prime phase into solid solution while simultaneously homogenizing the microstructure, d. heating the article at a temperature below the gamma prime solvus for a period of time sufficient to reprecipitate the gamma prime phase in refined form, whereby the reprecipitated gamma prime phase has a particle size of less than about 0.5 microns and the heat treated single crystal article has a temperature advantage of at least 30° F. over non-heat treated articles.

Claim 9

A method for producing nickel base superalloy single crystal articles which have a homogeneous microstructure and in which the gamma prime phase presents a refined morphology, including the steps of: a. providing a mass of nickel base superalloy material which is free from intentional additions of a cobalt, carbon, boron, and zirconium; and which consists essentially of from about 5 to 18% chromium; at least 5% of an element chosen from the group consisting of from 2 to 8% aluminum and from 1 to 5% titanium and mixture thereof; at least 5% of an element chosen from the group consisting of up to 10% molybdenum, up to 15% tungsten, up to 12% tantalum, up to 3% columbium, up to 3.5% hafnium, up to 7% rhenium, and mixtures thereof; balance essentially nickel, b. melting the nickel base superalloy and solidifying the alloy under conditions of unidirectional heat flow so as to produce a single crystal article having a microstructure which consists essentially of gamma prime particles in a gamma prime matrix, with the gamma prime particles having a particle size of about 1.5 microns, said article having an incipient melting temperature, in excess of about 2300° F., as a result of the absence of carbon, boron and zirconium, and a gamma prime solvus temperature, which is less than the incipient melting temperature, said microstructure being free of MC type carbides as a result of the absence of carbon and free from TCP phases, as a result of the absence of cobalt, c. heating the article to a temperature greater than the gamma prime solvus temperature and less than the incipient melting temperature for a period of time sufficient to dissolve substantially all of the gamma prime phase into solid solution while simultaneously homogenizing the microstructure, d. heating the article at a temperature below the gamma prime solvus for a period of time sufficient to reprecipitate the gamma prime phase in refined form, whereby the reprecipitated gamma prime phase has a particle size of less than about 0.5 microns and the heat treated single crystal article has a temperature advantage of at least 30° F. over non-heat treated articles.