Title:
Combustion Turbine Component Having Rare-Earth Elements and Associated Methods
Kind Code:
A1


Abstract:
A method of making a combustion turbine component includes forming a nanosized powder including a plurality of metals and at least one rare-earth element and agglomerating the nanosized powder to form a microsized powder including a plurality of metals and at least one rare-earth element. The microsized powder is processed to form a cohesive metallic mass and a primary aging heat treating is performed on the cohesive metallic mass. A solution heat treating may be performed on the cohesive metallic mass prior to the primary aging heat treating. A secondary aging treating may be performed on the cohesive metallic mass after the primary aging treating.



Inventors:
Kulkarni, Anand A. (Oviedo, FL, US)
James, Allister W. (Orlando, FL, US)
Arrell, Douglas J. (Oviedo, FL, US)
Application Number:
12/205956
Publication Date:
03/11/2010
Filing Date:
09/08/2008
Assignee:
Siemens Power Generation, Inc. (Orlando, FL, US)
Primary Class:
Other Classes:
419/20, 419/23
International Classes:
B22F3/12
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Primary Examiner:
KESSLER, CHRISTOPHER S
Attorney, Agent or Firm:
SIEMENS CORPORATION (Orlando, FL, US)
Claims:
That which is claimed is:

1. A method of making a combustion turbine component comprising: forming a nanosized powder comprising a plurality of metals and at least one rare-earth element; agglomerating the nanosized powder to form a microsized powder comprising a plurality of metals and at least one rare-earth element; processing the microsized powder to form a cohesive metallic mass; and performing a primary aging heat treating on the cohesive metallic mass.

2. The method of claim 1 wherein forming the nanosized powder comprises: forming an alloy powder comprising a plurality of metals; forming a metallic powder comprising at least one rare-earth element; and milling the alloy powder comprising a plurality of metals and the metallic powder comprising at least one rare-earth element together to form the nanosized powder.

3. The method of claim 2 wherein forming the metallic powder comprising the at least one rare-earth element comprises atomizing a metallic liquid comprising at least one rare-earth element to form a metallic powder comprising at least one rare-earth element and heat treating the metallic powder comprising at least one rare-earth element to form a metallic powder comprising at least one rare-earth element and at least one oxide thereof.

4. The method of claim 1 wherein performing the primary aging heat treating comprises: heating the cohesive metallic mass to a primary aging temperature being greater than a secondary carbide phase field temperature of the cohesive metallic mass and less than a solvus temperature of a gamma prime phase of the cohesive metallic mass; holding the cohesive metallic mass at the primary aging temperature; and cooling the cohesive metallic to a desired temperature related to the secondary carbide phase field temperature.

5. The method of claim 4 wherein the cohesive metallic mass is held at the primary aging temperature for 1.5 to 2.5 hours; wherein the cohesive metallic mass is cooled at a rate of 20° C. to 30° C. per second; and wherein the desired temperature is within 300° C. of the secondary carbide phase field temperature.

6. The method of claim 1 further comprising performing a solution heat treating on the cohesive metallic mass prior to the primary aging treating.

7. The method of claim 6 wherein performing the solution heat treating comprises: heating the cohesive metallic mass at a first heating rate to a temperature below the solvus temperature of a gamma prime phase of the cohesive metallic mass; heating the cohesive metallic mass at a second heating rate less than the first heating rate to a solution temperature being at least the solvus temperature of the gamma prime phase of the cohesive metallic mass; holding the cohesive metallic mass at the solution temperature; and cooling the cohesive metallic mass to a temperature below the solution temperature.

8. The method of claim 7 wherein the first heating rate is in a range of 10° C. to 25° C. per minute; wherein the second heating rate is in a range of 1° C. to 3° C. per minute; wherein the cohesive metallic mass is held at the solution temperature for 1.5 to 2.5 hours; and wherein the cohesive metallic mass is cooled at a rate of 20° C. to 30° C. per minute.

9. The method of claim 6 further comprising performing a secondary aging heat treating on the cohesive metallic mass after performing the primary aging heat treating.

10. The method of claim 9 wherein performing the secondary aging heat treating comprises: heating the cohesive metallic mass to a secondary carbide phase field temperature of the cohesive metallic mass; holding the cohesive metallic mass at the secondary carbide phase field temperature; and cooling the cohesive metallic mass to below the secondary carbide phase field temperature.

11. The method of claim 10 wherein the cohesive metallic mass is heated to the secondary carbide phase field temperature at a rate of less than 25° C. per minute; wherein the cohesive metallic mass is held at the secondary carbide phase field temperature for 15 to 25 hours; and wherein the cohesive metallic mass is cooled at a rate of 20° C. to 30° C. per minute.

12. A method as in claim 1 wherein the metallic powder comprising at least one rare-earth element further comprises at least one oxide of the at least one rare-earth element,

13. A method as in claim 1 wherein processing the microsized powder to form the cohesive metallic mass comprises compacting the microsized powder to form a cohesive metallic mass.

14. A method as in claim 1 wherein processing the microsized powder to form the cohesive metallic mass comprises thermally spraying the microsized powder onto a metallic substrate.

15. A method as in claim 1 further comprising forming the combustion turbine component from the cohesive metallic mass.

16. A method of making a combustion turbine component comprising: forming an alloy powder comprising a plurality of metals; forming a metallic powder comprising at least one rare-earth element; milling the alloy powder comprising a plurality of metals and the metallic powder comprising at least one rare-earth element together to form a nanosized powder comprising a plurality of metals and at least one rare-earth element; agglomerating the nanosized powder to form a microsized powder comprising a plurality of metals and at least one rare-earth element; processing the microsized powder to form a cohesive metallic mass; performing a solution heat treating on the cohesive metallic mass; and performing a primary aging heat treating on the cohesive metallic mass.

17. A method as in claim 16 wherein the metallic powder comprising at least one rare-earth element further comprises at least one oxide of the at least one rare-earth element.

18. A method as in claim 16 wherein forming the metallic powder comprises atomizing a metallic liquid comprising at least one rare-earth element to form a metallic powder comprising at least one rare-earth element and heat treating the metallic powder comprising at least one rare-earth element to form the metallic powder comprising the at least one rare-earth element and at least one oxide thereof.

19. A method as in claim 16 wherein forming the alloy powder comprising the plurality of metals comprises atomizing an alloy liquid comprising a plurality of metals to form an alloy powder comprising a plurality of metals.

20. A method as in claim 16 wherein processing the microsized powder to form the cohesive metallic mass comprises compacting the microsized powder to form a cohesive metallic mass.

21. A method as in claim 16 wherein processing the microsized powder to form the cohesive metallic mass comprises thermally spraying the microsized powder onto a metallic substrate.

22. A method of making a combustion turbine component comprising: forming a nanosized powder comprising a plurality of metals and at least one rare-earth element; agglomerating the nanosized powder to form a microsized powder comprising a plurality of metals and at least one rare-earth element; processing the microsized powder to form a cohesive metallic mass; and performing a solution heat treating on the cohesive metallic mass.

23. A method as in claim 22 wherein the metallic powder comprising at least one rare-earth element further comprises at least one oxide of the at least one rare-earth element.

24. A method as in claim 22 wherein processing the microsized powder to form the cohesive metallic mass comprises compacting the microsized powder to form a cohesive metallic mass.

25. A method as in claim 22 wherein processing the microsized powder to form the cohesive metallic mass comprises thermally spraying the microsized powder onto a metallic substrate.

Description:

FIELD OF THE INVENTION

The present invention relates to the field of metallurgy, and, more particularly, to methods of making rare-earth element strengthened combustion turbine components.

BACKGROUND OF THE INVENTION

Components of combustion turbines are routinely subjected to harsh environments that include rigorous mechanical loading conditions at high temperatures, high temperature oxidization, and exposure to corrosive media. The structural stability of such components is often provided by nickel or cobalt base superalloys, for example, due to their exemplary high temperature mechanical properties, such as creep resistance and fatigue resistance.

Creep is the term used to describe the tendency of a solid material to slowly move or deform permanently to relieve stresses. It occurs as a result of long-term exposure to levels of stress that are below the yield strength or ultimate strength of the material. Creep is more severe in materials that are subjected to heat for long periods and near their melting point, such as alloys out of which combustion turbine components are formed. If a turbine blade, for example, were to deform so that it contacted the turbine cylinder, a catastrophic failure may result. Therefore, a high creep resistance is an advantageous property for a combustion turbine component to possess.

Fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. Given the numerous fatigue cycles a combustion turbine component may endure, a high fatigue resistance is likewise an advantageous property for a combustion turbine component to possess.

One way to strengthen a material, enhancing both its creep resistance and its fatigue resistance, is known as dispersion strengthening. Dispersion strengthening typically occurs by introducing a fine dispersion of particles into a material, for example, a metallic component. Dispersion strengthening can occur by adding material constituents that form particles when the constituents are added over their solubility limits.

Alternatively, dispersion strengthening may be performed by adding stable particles to a material, in which these particles are not naturally occurring in the material. These particles strengthen the material and may remain unaltered during metallurgical processing. Typically, the closer the spacing of the particles, the stronger the material. The fine dispersion of close particles restricts dislocation movement, which is the mechanism by which creep rupture may occur.

Previous dispersion strengthening methods include the introduction of thoria, alumina, or yttria particles into materials out of which combustion turbine components are formed. Thoria, alumina, and yttria are oxides that possess a higher bond energy than oxides of metals, such as iron, nickel, cobalt, or chromium that are typically used as the base metal of combustion turbine components.

For example, U.S. Pat. Pub. 2008/0026160 to Taylor et al. discloses a method for coating combustion turbine blades. A low yttria powder and a high yttria powder are formed by a spray dry and sinter method, wherein a slurry is prepared in a dispersion medium. The slurry is granulated by spray drying, then sieved and classified, to form each powder. The powders are blended together in a desired ratio and thermally sprayed onto a metallic substrate of the combustion turbine blade.

U.S. Pat. Pub. 2007/0141370 to Kerber discloses a combustion turbine component with a rare-earth nanoparticle surface treatment. The combustion turbine component is dipped into a solution containing the nanoparticles then dried. The combustion turbine component is then heat treated to form a self-protective oxide coating.

U.S. Pat. Pub. 2007/0044870 to Woodfield et al. discloses a method for making a combustion turbine component from a titanium-base alloy having an oxide dispersion therein. A nonmetallic precursor compound, collectively containing desired constituent elements of the combustion turbine component in their respective desired proportions, is provided. The constituent elements together form a titanium-base alloy having a stable-oxide-forming additive element therein, such as magnesium, calcium, and yttrium. The stable-oxide-forming additive element is to form a stable oxide in the titanium-based alloy from which the combustion turbine component is to be formed. At least one additive element is present at a level greater than its room-temperature solid solubility limit in the titanium-base alloy. The precursor compounds are chemically reduced to produce an alloy, without melting the alloy, having oxides of the stable-oxide-forming additive element. The combustion turbine component is formed from the alloy.

U.S. Pat. No. 5,049,355 to Gennari et al. discloses a process for producing a dispersion strengthened alloy of a base metal. A base metal powder and a powder comprising thoria, alumina, and/or yttria are pressed into a blank form. The pressed blank form is sintered so that the thoria, alumina, and/or yttria are homogenously dispersed throughout the base metal. A combustion turbine component may be formed from the blank form.

U.S. Pat. No. 5,868,876 to Biano et al. discloses a process for producing a creep resistant molybdenum alloy, A slurry of molybdenum oxide and an aqueous solution of lanthanum, cerium, and/or thoria is formed. The slurry is heated in a hydrogen atmosphere to produce a metallic powder. The powder is pressed then sintered. Finally, the sintered powder is thermomechanically processed to produce a molybdenum alloy having an oxide dispersion of lanthanum, cerium, and/or thoria. A combustion turbine component may be formed from the alloy.

The pursuit of increased combustion turbine efficiency has led to increased turbine section inlet temperatures, and thus combustion turbine components made from different materials and having increased high temperature creep and fatigue resistance may be desirable.

SUMMARY OF THE INVENTION

In view of the foregoing background, it is therefore an object of the present invention to provide a method of making a rare-earth oxide strengthened combustion turbine component.

This and other objects, features, and advantages in accordance with the present invention are provided by a method of making a combustion turbine component that may comprise forming a nanosized powder comprising a plurality of metals and at least one rare-earth element and agglomerating the nanosized powder to form a microsized powder comprising a plurality of metals and at least one rare-earth element. The microsized powder may be processed to form a cohesive metallic mass. In addition, a primary aging heat treating may be performed on the cohesive metallic mass. This primary aging heat treating may promote the precipitation of primary carbides at grain boundaries of the cohesive metallic mass.

Forming the nanosized powder may comprise forming an alloy powder comprising a plurality of metals and forming a metallic powder comprising at least one rare-earth element. Forming the nanosized powder may also include milling the alloy powder comprising a plurality of metals and the metallic powder comprising at least one rare-earth element together to form the nanosized powder.

Forming the metallic powder comprising the at least one rare-earth element may comprise atomizing a metallic liquid comprising at least one rare-earth element to form a metallic powder comprising at least one rare-earth element and heat treating the metallic powder comprising at least one rare-earth element to form a metallic powder comprising at least one rare-earth element and at least one oxide thereof.

Additionally or alternatively, forming the metallic powder comprising the at least one rare-earth element may include crushing an ingot comprising at least one rare-earth element. Additionally or alternatively, forming the metallic powder comprising the at least one rare-earth element may include atomizing a metallic liquid comprising at least one rare-earth element to form a metallic powder comprising at least one rare-earth element. Forming the metallic powder may also include heat treating the metallic powder to form a metallic powder comprising at least one rare-earth element and at least one oxide thereof. In addition, forming the alloy powder comprising the plurality of metals may include atomizing an alloy liquid comprising a plurality of metals to form an alloy powder comprising a plurality of metals. The metallic powder comprising at least one rare-earth element may include at least one oxide of the at least one rare-earth element.

Performing the primary aging heat treating may comprise heating the cohesive metallic mass to a primary aging temperature being greater than a secondary carbide phase field temperature of the cohesive metallic mass and less than a solvus temperature of a gamma prime phase of the cohesive metallic mass. The cohesive metallic mass may be held at the primary aging temperature. The cohesive metallic may be cooled to a desired temperature related to the secondary carbide phase field temperature.

During the primary aging heat treating, the cohesive metallic mass may be held at the primary aging temperature for 1.5 to 2.5 hours, the cohesive metallic mass may be cooled at a rate of 20° C. to 30° C. per second, and the desired temperature may be within 300° C. of the secondary carbide phase field temperature.

A solution heat treating may be performed on the cohesive metallic mass prior to the primary aging treating. This solution heat treating homogenizes the cohesive metallic mass. Performing the solution heat treating may comprise heating the cohesive metallic mass at a first heating rate to a temperature below the solvus temperature of a gamma prime phase of the cohesive metallic mass and heating the cohesive metallic mass at a second heating rate less than the first heating rate to a solution temperature being at least the solvus temperature of the gamma prime phase of the cohesive metallic mass. The cohesive metallic mass may be held at the solution temperature. The cohesive metallic mass may be cooled to a temperature below the solution temperature.

While performing the solution heat treating, the first heating rate may be in a range of 10° C. to 25° C. per minute and the second heating rate may be in a range of 1° C. to 3° C. per minute. The cohesive metallic mass may be held at the solution temperature for 1.5 to 2.5 hours and the cohesive metallic mass may be cooled at a rate of 20° C. to 30° C. per minute.

A secondary aging heat treating may be performed on the cohesive metallic mass after performing the primary aging heat treating. This secondary aging heat treating may promote the precipitation of secondary carbides at the grain boundaries of the cohesive metallic mass.

Performing the secondary aging heat treating may comprise heating the cohesive metallic mass to a secondary carbide phase field temperature of the cohesive metallic mass and holding the cohesive metallic mass at the secondary carbide phase field temperature. In addition, performing the secondary aging heat treating may include cooling the cohesive metallic mass to below the secondary carbide phase field temperature.

During the secondary aging heat treating, the cohesive metallic mass may be heated to the secondary carbide phase field temperature at a rate of less than 25° C. per minute and the cohesive metallic mass may be held at the secondary carbide phase field temperature for 15 to 25 hours. The cohesive metallic mass may be cooled at a rate of 20° C. to 30° C. per minute.

Processing the microsized powder to form the cohesive metallic mass may comprise compacting the microsized powder to form a cohesive metallic mass having a desired shape. Also, processing the microsized powder to form the cohesive metallic mass may comprise thermally spraying the microsized powder onto a metallic substrate to thereby form the cohesive metallic mass. Furthermore, processing the microsized powder to form the cohesive metallic mass may comprise physical vapor deposition of the microsized powder onto a metallic substrate. The combustion turbine component may be formed from the cohesive metallic mass.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of a method in accordance with the present invention.

FIG. 2 is a more detailed flowchart of the solution heat treating of FIG. 1.

FIG. 3 is a more detailed flowchart of the primary aging heat treating of FIG. 1.

FIG. 4 is more detailed flowchart of the secondary aging heat treating of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

A method of making a combustion turbine component in accordance with the present invention is now described generally with reference to the flowchart 10 of FIG. 1. After the start (Block 12), at Block 14 a nanosized powder comprising a plurality of metals and at least one rare-earth element is formed. Typically, the particle size distribution of the nanosized powder may be from 10 nm to 100 nm, although other particle size distributions may also result.

The nanosized powder may be formed by forming an alloy powder comprising a plurality of metals, forming a metallic powder comprising at least one rare-earth element, and milling the alloy powder and the metallic powder together. Those of skill in the art will understand that the alloy powder and the metallic powder may be mixed by conventional processes first, then milled together thereafter, or that the alloy powder and the metallic powder may be mixed by the milling process. The milling is preferably cryomilling, although other milling processes such as jet milling and ball milling may be used, Oxides of the plurality of metals and/or the at least one rare-earth element may form during the milling process.

It should be noted that the alloy powder may be oxide free or, alternatively, may include oxides of the plurality of metals. It should likewise be noted that the metallic powder may be oxide free or, alternatively, may include at least one oxide of the at least one rare-earth element.

The metallic powder comprising the at least one rare-earth element may be formed by crushing an ingot. The ingot may contain at least one oxide of the at least one rare-earth element before crushing, or at least one oxide may be formed during the crushing process. The crushing is performed by conventional processes known to those of skill in the art. After crushing, the metallic powder may be milled to form a metallic powder having a desired particle size distribution and comprising at least one rare-earth element and at least one oxide thereof.

Forming the alloy powder comprising a plurality of metals may comprise atomizing an alloy liquid. The alloy liquid may comprise at least two of Co, Cr, Al, Fe, Ni, Mo, W, Ti, and Re. Some exemplary alloy liquids include CoNiCrAl, FeCrAl, NiCrAl, and Fe3Al.

The metallic powder comprising at least one rare-earth element may be formed by atomizing a metallic liquid. The at least one rare-earth element may be an element from the lanthanide and the actinide group of the periodic table of elements.

The alloy liquid and the metallic liquid may each be atomized in an oxidizing atmosphere or in an inert atmosphere. The alloy liquid and the metallic liquid need not each be atomized in the same atmosphere. For example, the alloy liquid may be atomized in an inert atmosphere while the metallic liquid is atomized in an oxidizing atmosphere, or vice versa. An exemplary inert atmosphere comprises nitrogen and/or argon, although it is to be understood that other inert gasses may be used. An oxidizing atmosphere comprises oxygen. Those of skill in the art will appreciate that other atmospheres may also be used, and that such atmospheres may be at desired temperatures and desired pressures.

Atomization in an oxidizing atmosphere may facilitate the formation of in-situ oxide shells that may enhance certain properties of the alloy liquid and/or the metallic liquid and the resulting alloy powder and/or metallic powder. Similarly, atomization in an inert atmosphere may increase the likelihood that each droplet or particle formed during the atomization process has a uniform size, shape, and/or chemistry.

Particle size distribution of the alloy powder and the metallic powder is preferably in a range of 10 μm to 100 μm, for example. The atomization may produce an amorphous alloy powder and/or an amorphous metallic powder. Alternatively, the atomization may produce a crystalline alloy powder and/or a crystalline metallic powder.

Those skilled in the art will appreciate that the alloy liquid and the metallic liquid may be formed by melting ingots of a pure metal or of a desired alloy. Moreover, the alloy liquid and metallic liquid may be formed by melting ingots of different metals, mixing when melted or during melting to form an alloy liquid or metallic liquid having a desired composition. It is to be understood that the melting and resulting formation of the alloy liquid and the metallic liquid may occur prior to atomization or as part of the atomization process. In addition, those of skill in the art will appreciate that the alloy liquid and/or the metallic liquid may include solid solution strengtheners and grain boundary strengtheners.

It should be noted that the alloy liquid and/or the metallic liquid may also be formed by melting an alloy powder and a metallic powder, respectively. Various processes may be used to melt the ingots or powders.

The metallic powder may be optionally heat treated to form a metallic powder comprising at least one rare-earth element and at least one oxide thereof. Such rare-earth oxides may provide the combustion turbine component with a variety of advantageous properties including enhanced oxidation and wear resistance.

At Block 16, the nanosized powder is agglomerated to form a microsized powder comprising a plurality of metals and at least one rare-earth element. A variety of surfactants and blending mixtures may be used during the agglomeration. The agglomeration may be performed by dispersing the nanosized powder in a polar or non-polar solvent into which a suitable plasticizer, binder, and dispersant have been added, thereby forming a colloid. A variety of plasticizers, binders, and dispersants may also be used, as will be appreciated by those of skill in the art. The charge around the particles of the powder may be controlled with charge controlling agents (CCA's) or by altering the pH of the solvent, thereby changing the zeta potential of the system. This allows selective control of the size of the agglomerated particles, for example 10 μm to 100 μm, as the zeta potential of the system directly affects the size of the agglomerated particles. The agglomerated particles may then be removed from the colloid by conventional processes known to those of skill in the art to form the microsized powder. It will be appreciated that the microsized powder comprises nanosized particulates of the plurality of metals, the at least one rare-earth element, and optionally oxides of the plurality of metals and/or the at least one rare-earth element.

It should be understood that the alloy powder comprising a plurality of metals and the metallic powder comprising at least one rare-earth element may be milled separately to form respective nanosized powders. These nanosized powders may be mixed by conventional processes before the agglomeration process or may be mixed by the agglomeration process itself.

After agglomeration, the microsized powder may be subjected to an optional heat treatment. This heat treating may be performed in an oxidizing atmosphere to produce oxides of the plurality of metals and/or the at least one rare-earth element. The heat treating may alternatively be performed in an inert atmosphere, for example a vacuum, to reduce the amount of non rare-earth oxides in the microsized powder. Alternatively, the heat treating may stabilize a microstructure of the cohesive metallic mass.

At Block 18, the microsized powder is processed to form a cohesive metallic mass. Those of skill in the art will appreciate that the microsized powder may be processed to form a cohesive metallic mass having a desired shape, for example an airfoil, and that the microsized powder may be processed by compaction, mechanical working, plasma spraying, or various deposition processes. The cohesive metallic mass may also have the shape of a portion of a combustion turbine component or may have other shapes, such as a flat sheet.

Processing the microsized powder to form the cohesive metallic mass may include compacting the microsized powder. Those of skill in the art will appreciate that the microsized powder may be compacted by hot isostatic pressing, cold compaction, sintering, or other conventional processes. Further, the microsized powder may be compacted by more than one of the preceding conventional compaction processes.

Alternatively, processing the microsized powder to form the cohesive metallic mass may include thermally spraying the microsized powder onto a metallic substrate to form the cohesive metallic mass. It is to be understood that any of a number of commercially available thermal spraying process may be employed, melting the microsized powder and accelerating it at the metallic substrate. The metallic substrate may comprise an aluminum, cobalt, or iron based superalloy, although other metallic substrates may also be used.

At Block 20, a solution heat treating is performed on the cohesive metallic mass. The goal of the solution heat treating is to homogenize the constituents of the cohesive metallic mass. Those of skill in the art will appreciate that this solution heat treating is optional, particularly if the cohesive metallic mass comprises a cobalt or iron based superalloy.

Flowchart 30 of FIG. 2 shows one embodiment of the solution heat treating in detail. After the start of the solution heat treating (Block 32), at Block 34 the cohesive metallic mass is heated at a first heating rate to a temperature below the solvus temperature of a gamma prime phase of the cohesive metallic mass. Preferably, the cohesive metallic mass will be heated to not less than 100° C. below the solvus temperature, although of course, in some applications, the cohesive metallic mass may be heated to other temperatures. This will take most of the gamma prime phase into solution and may homogenize the cohesive metallic mass. The first heating rate may be in a range of 10° C. to 25° C. per minute, although other suitable heating rates may be used.

At Block 36 the cohesive metallic mass is heated at a second heating rate less than the first heating rate to a solution temperature being at least the solvus temperature of the gamma prime phase of the cohesive metallic mass. The second heating rate may be in a range of 1° C. to 3° C. per minute, although other suitable heating rates may be used.

At Block 38, the cohesive metallic mass is held at the solution temperature. The cohesive metallic mass may be held at the solution temperature for 1.5 to 2.5 hours, for example.

At Block 40, the cohesive metallic mass is cooled to a temperature below the solution temperature. The cohesive metallic mass may be cooled at a rate of 20° C. to 30° C. per minute, for example. The rate of cooling from the solution temperature to 300° C. below the solvus temperature may be adjusted to control the size and shape of the gamma prime phase as it precipitates during the cooling. For example, a rapid cooling promotes a fine distribution of the gamma prime particles in the gamma matrix of the cohesive metallic mass. If this cooling were performed at a slow pace, diffusion would occur and the gamma prime particles would grow, becoming coarser. The cooling may comprise a rapid gas cooling using argon, nitrogen, or other suitable gasses

The cohesive metallic mass may optionally be cooled to room temperature, although in some applications it may be cooled to a temperature at which another heat treating is to be performed.

Block 42 indicates the end of the solution heat treating. Optionally, one or more desired coatings may be formed on the cohesive metallic mass after the solution heat treat treating, as will be appreciated by one of skill in the art.

Referring again to FIG. 1, at Block 22, a primary aging heat treating is performed on the cohesive metallic mass. The goal of the primary aging heat treatment is to further refine the gamma prime particles, to promote the precipitation of primary carbides at grain boundaries of the crystal structure of the cohesive metallic mass, and to refine the shapes of those precipitates for optimal mechanical properties. Primary carbides include TiC, NbC, and TaC.

Those skilled in the art will understand that the primary aging heat treating is particularly advantageous for treating the cohesive metallic mass when it comprises a cobalt based superalloy and that, in some applications, the primary aging heat treating may be performed before other heat treatings or may be the only heat treating.

Flowchart 50 of FIG. 3 shows one embodiment of the primary aging heat treating in detail. After the start (Block 52), at Block 54 the cohesive metallic mass is heated to a primary aging temperature being greater than a secondary carbide phase field temperature of the cohesive metallic mass and less than the solves temperature. It should be noted that, if a solution heat treating is performed on the cohesive metallic mass prior to the primary aging heat treating, the solution heat treating may cool the cohesive metallic mass to the primary aging temperature and therefore the primary aging heat treating need not include the aforementioned heating.

At Block 56, the cohesive metallic mass is held at the primary aging temperature. The cohesive metallic mass may be held at the primary aging temperature for 1.5 to 2.5 hours, although of course the cohesive metallic mass may also be held at the primary aging temperature for other periods of time.

At Block 58, the cohesive metallic mass is cooled to a desired temperature related to the secondary carbide phase field temperature. The cohesive metallic mass may be cooled at a rate of 20° C. to 30° C. per second, and the desired temperature may be within 300° C. of the secondary carbide phase field temperature. The cohesive metallic mass may optionally be cooled to room temperature, although in some applications it may be cooled to a temperature at which another heat treating is to be performed. Block 60 indicates the end of the primary aging heat treating.

Referring yet again to FIG. 1, at Block 24, an optional secondary aging heat treating is performed on the cohesive metallic mass. The goal of the secondary aging heat treating is to promote the precipitation of secondary carbides at grain boundaries of the crystal structure of the cohesive metallic mass. Secondary carbides include Cr23C6, Cr21Mo2C6, and Cr21W2C6.

Flowchart 70 of FIG. 4 shows one embodiment of the optional secondary aging heat treating in detail. After the start (Block 72), at Block 74, the cohesive metallic mass is heated to a secondary carbide phase field temperature of the cohesive metallic mass. The cohesive metallic mass may be heated to the secondary carbide phase field temperature at a rate of less than 25° C. per minute.

It should be noted that, if a primary aging heat treating is performed on the cohesive metallic mass prior to the secondary aging heat treating, the solution heat treating may cool the cohesive metallic mass to the secondary carbide phase field temperature and therefore the secondary aging heat treating need not include the aforementioned heating.

At Block 76, the cohesive metallic mass is held at the secondary carbide phase field temperature. The cohesive metallic mass may be held at the secondary carbide phase field temperature for 15 to 25 hours. The cohesive metallic mass may be held at other the secondary carbide phase field temperature for other suitable periods of time, as will be appreciated by those skilled in the art.

At Block 78, the cohesive metallic mass is cooled to below the secondary aging temperature. The cohesive metallic mass may be cooled at a rate of 20° C. to 30° C. per minute, although other cooling rates may also be used

At Block 80, the cohesive metallic mass is cooled to room temperature, although the cohesive metallic mass may also be cooled to other desired temperatures. Block 82 indicates the end of the secondary aging heat treating.

At Block 26, a combustion turbine component is formed from the cohesive metallic mass. It is to be understood that the combustion turbine component may be formed by a variety of processes known to those of skill in the art. For example, the cohesive metallic mass may be forged or otherwise mechanically worked into the desired combustion turbine component. Alternatively, the cohesive metallic mass may already be of a desired shape and the formation may include attaching the cohesive metallic mass to other cohesive metallic masses to form the desired combustion turbine component. Additionally or alternatively, the forming may include forming one or more coatings (bond coatings, thermal barrier coatings, wear resistant coatings, other alloy coatings, etc) on the cohesive metallic mass to thereby form the combustion turbine component. Block 28 indicates the end of the method.

Moreover, after formation, the combustion turbine component may be further heat treated in a desired atmosphere, such as an inert atmosphere or an oxidizing atmosphere, at a desired temperature and at a desired pressure. Additionally, a bond coating, a wear resistant coating, and/or a thermal barrier coating may be formed on the combustion turbine component after formation. The final composition of the combustion turbine component and/or the cohesive metallic mass may be from 1% to 12%, by weight, total, of rare-earth elements.

Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.