Nickel-based superalloys having microstructures containing rafting-resistant gamma prime phase and articles prepared therefrom - Patents.com

Abstract

To provide a nickel-based superalloy with a microstructure including a rafting-resistant gamma prime phase, and an article prepared from the nickel-based superalloy.SOLUTION: In a non-limiting example, an article having a body including a nickel-based superalloy is provided. The nickel-based superalloy has a microstructure that includes a gamma phase matrix and a gamma prime phase including a plurality of rafting-resistant gamma prime particles dispersed in the gamma phase matrix. The rafting-resistant gamma prime particles have an average particle perimeter of about 3 microns to about 15 microns, an average aspect ratio of about 1.2 to about 3, and where the microstructure of the nickel-based superalloy is substantially uniform throughout the body.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] This disclosure relates generally to nickel-base superalloys and articles prepared from nickel-base superalloys. More specifically, this disclosure relates to nickel-base superalloys and articles prepared from nickel-base superalloys having a microstructure including a rafting-resistant gamma prime phase. [Background technology]

[0002] Nickel (Ni)-based superalloys are widely used in the manufacture of various industrial components, including, but not limited to, gas turbine parts, aircraft engine components, chemical plant materials, automotive turbocharger rotors, and high-temperature furnace materials, due to their high strength in high-temperature operating environments. Ni-based superalloys typically have a microstructure containing gamma (γ) and gamma prime (γ') phases. The γ phase can serve as a matrix for the γ' phase and is sometimes referred to as the γ matrix. In the γ' phase, multiple gamma prime particles ("γ' particles") or precipitates can be dispersed in the γ matrix. It is generally recognized that the γ' phase is primarily responsible for the high strength of Ni-based superalloys at elevated temperatures, and that a higher volume fraction or volume percentage of the γ' phase in Ni-based superalloys is typically associated with a higher strengthening effect of Ni-based superalloys.

[0003] Despite their attractive properties, Ni-base superalloys, particularly those with a single-grain microstructure (e.g., single-crystal nickel-base superalloys), can be susceptible to crack growth or rafting. For example, industrial components formed from Ni-base superalloys can experience crack growth, fracture, or rafting under certain operating conditions, which can lead to operational failures, significant maintenance, and / or repair costs. The challenge becomes even more severe in applications involving certain heavy components, such as gas turbine blades, which can weigh up to 25 kg / 55 lbs. Such heavy components are more difficult to uniformly heat treat, which makes them more susceptible to crack growth compared to much lighter components, such as aircraft engine components, thus limiting the selection of Ni-base superalloys for use in applications involving certain heavy components.

[0004] The conventional approach to minimizing crack growth in Ni-base superalloys and articles prepared from them is to reduce the volume fraction of the γ' phase in the Ni-base superalloy, but this approach results in sacrificing the strengthening effect of the γ' phase in the Ni-base superalloy. Summary of the Invention

[0005] A first aspect according to the present disclosure provides an article comprising: a body having a first sidewall, a second sidewall opposite the first sidewall, and a body dimension extending between the first sidewall and the second sidewall, the body further comprising a nickel-base superalloy having a microstructure, the microstructure comprising a gamma phase matrix and a gamma prime phase including a plurality of rafting resistant gamma prime particles dispersed in the gamma phase matrix, the plurality of rafting resistant gamma prime particles having an average particle perimeter of about 3.0 microns to about 15.0 microns and an average aspect ratio of about 1.2 to about 3.0, and the nickel-base superalloy microstructure is substantially uniform throughout the body dimension.

[0006] A second embodiment according to the present disclosure is a nickel-base superalloy comprising, in weight percent of the nickel-base superalloy, about 4.0 weight percent to about 7.0 weight percent aluminum (Al), about 5.0 weight percent to about 10.0 weight percent chromium (Cr), about 6.0 weight percent to about 10.0 weight percent cobalt (Co), 0 weight percent to about 1.5 weight percent hafnium (Hf), 0 weight percent to about 3.0 weight percent molybdenum (Mo), 0 weight percent to about 2.0 weight percent niobium (Nb), 0 weight percent to about 6.0 weight percent rhenium (Re), about 4.0 weight percent to about 10.0 weight percent tantalum (Ta), and 0 weight percent to about 4.0 weight percent titanium (T i), about 4.0 weight percent to about 8.0 weight percent tungsten (W), and the balance Ni and incidental impurities, wherein the nickel-base superalloy has a microstructure comprising a gamma phase matrix and a gamma prime phase comprising a plurality of rafter-resistant gamma prime particles dispersed in the gamma phase matrix, the plurality of rafter-resistant gamma prime particles having an average particle perimeter of about 3.0 microns to about 15.0 microns and an average aspect ratio of about 1.2 to about 3.0, wherein one or both of the average particle perimeter and average aspect ratio of the plurality of rafter-resistant gamma prime particles are substantially uniform throughout the microstructure of the nickel-base superalloy.

[0007] A third aspect according to the present disclosure provides a method for preparing an article from a workpiece having a body comprising a nickel-base superalloy, the method comprising: heating the workpiece to a subsolvus temperature at a heat treatment rate, the subsolvus temperature being below a γ' solvus temperature of the nickel-base superalloy; heat treating the workpiece by holding the workpiece at the subsolvus temperature for a predetermined heat treatment time; and cooling the workpiece from the subsolvus temperature at a cooling rate of less than 75°F / minute for a predetermined cooling time to produce the article, the method further comprising adjusting one or both of the heat treatment rate and the cooling rate to control formation of a microstructure of the nickel-base superalloy, the microstructure comprising a gamma phase matrix and a gamma prime phase comprising a plurality of rafting-resistant gamma prime particles dispersed in the gamma phase matrix, the plurality of rafting-resistant gamma prime particles having an average particle perimeter of about 3.0 microns to about 15.0 microns and an average aspect ratio of about 1.2 to about 3.0.

[0008] Various objects, features, and advantages of the present disclosure will become better understood from the following detailed description taken in conjunction with the accompanying drawings, in which like reference numerals designate the same or similar parts throughout the several views. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view of a rotating blade of a type in which embodiments of the present disclosure may be employed; [Figure 2] 2 is a cross-sectional view of a portion of the blade of FIG. 1 taken along line 2-2, according to an embodiment of the present disclosure. [Figure 3a-3c] 3a, 3b, and 3c show photomicrographs of portions of the microstructure of Ni-base superalloy I (reference nickel-base superalloy) in the inner section (FIG. 3a), middle section (FIG. 3b), and outer section (FIG. 3c) of the body of an article prepared from Ni-base superalloy I, according to an embodiment of the present disclosure. [Figures 4a-4c]4a, 4b, and 4c show micrographs of portions of the microstructure of Ni-base superalloy II in the inner section (FIG. 4a), middle section (FIG. 4b), and outer section (FIG. 4c) of the body of an article prepared from Ni-base superalloy II, according to an embodiment of the present disclosure. [Figures 5a-5c] 5A and 5B show micrographs of portions of the microstructure of Ni-base superalloy III in the inner section (FIG. 5a), middle section (FIG. 5b), and outer section (FIG. 5c) of the body of an article prepared from Ni-base superalloy III according to an embodiment of the present disclosure. [Figure 6] FIG. 2 illustrates the crystal structure of the γ′ phase of Ni-based superalloy Ni3Al, according to an embodiment of the present disclosure. [Figure 7] 1A-1C are box plots of the measured average aspect ratios (AR) of γ' grains of Ni-base superalloys I, II, and III for the inner section (a), middle section (b), and outer section (c) of the body of an article having the corresponding Ni-base superalloy according to an embodiment of the present disclosure. [Figure 8] 1A-1C are box plots of the measured average grain sizes of γ' grains of Ni-base superalloys I, II, and III for the inner section (a), middle section (b), and outer section (c) of the body of an article having the corresponding superalloy, according to an embodiment of the present disclosure. [Figure 9] 1A-1C are scatter plots of the measured average aspect ratio (AR) versus the measured average perimeter (microns) of γ′ grains of Ni-base superalloys I, II, and III for the inner section (a), middle section (b), and outer section (c) of the body of an article having the corresponding superalloy, according to an embodiment of the present disclosure. [Figure 10a] FIG. 10 shows a representative example of a photomicrograph with mean grain parameters of the gamma prime phase including a mean perimeter of about 2.1 microns for a corresponding Ni-base superalloy according to an embodiment of the present disclosure. [Figure 10b] FIG. 10 shows a representative example of a micrograph with average grain parameters of the γ′ phase including an aspect ratio AR of about 7.0 for a corresponding Ni-base superalloy according to an embodiment of the present disclosure. [Figure 10c]FIG. 1 shows a representative example of a micrograph with average grain parameters of the gamma prime phase including a perimeter of about 11.5 microns and an aspect ratio AR of about 1.2 for a corresponding Ni-base superalloy according to an embodiment of the present disclosure. [Figure 10d] FIG. 10 shows a representative example of a photomicrograph with average grain parameters of the gamma prime phase comprising a perimeter of about 25.0 microns for a corresponding Ni-base superalloy according to an embodiment of the present disclosure. [Figure 11] 1A and 1B show a comparison of crack growth length over time between an article prepared using a conventional Ni-base superalloy (Reference Superalloy I) and an article prepared using Ni-base superalloy II, respectively, in accordance with an embodiment of the present disclosure. [Figure 12] 1 is a flowchart illustrating a method for preparing an article from a workpiece having a body comprising a Ni-base superalloy, according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] It should be noted that the drawings of the present disclosure may not be drawn to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure.

[0011] Certain embodiments are described herein to provide a general understanding of the principles of the structure, function, manufacture, and use of the methods, systems, and devices disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the methods, systems, and devices specifically described herein and illustrated in the accompanying drawings are non-limiting embodiments. Features illustrated or described in connection with one embodiment may be combined with features of other embodiments. Such modifications and variations are intended to be within the scope of the present disclosure.

[0012] In the following specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. As used herein, the term "or" does not mean exclusive, unless the context clearly dictates otherwise, and refers to at least one of the referenced components present, and includes cases where combinations of the referenced components may be present. When an element or layer is referred to as "on," "engaged," "adjacent," "connected," or "coupled" to another element or layer, it may be directly on, engaged, adjacent, connected, or coupled to the other element or layer, or intervening elements or layers may be present. Conversely, when an element is referred to as "directly on," "directly engaged," "directly adjacent," "directly connected," or "directly coupled" to another element or layer, there may not be intervening elements or layers. Other words used to describe relationships between elements should be interpreted similarly (e.g., "between" versus "directly between"). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0013] The present disclosure offers advantages and alternatives over existing nickel-base superalloys and articles prepared therefrom by providing a nickel-base superalloy configured with a microstructure including a gamma phase matrix and a γ' phase having a plurality of rafter-resistant γ' particles dispersed in the gamma phase matrix. The parameters of the rafter-resistant γ' particles are selected and controlled to provide a substantially uniform microstructure of the nickel-base superalloy throughout the article prepared therefrom, thereby imparting reduced crack growth rates in the article compared to articles prepared therefrom. Additionally, the Ni-base superalloy of the present disclosure allows for a high volume fraction of the γ' phase to be present so as to maximize the benefit of the high strengthening effect of the γ' phase without the need to reduce the volume fraction of the γ' phase. The approach of the present disclosure is advantageous over conventional approaches that reduce the volume fraction of the γ' phase at the expense of the strengthening effect of the γ' phase. Additionally, the disclosed approach is particularly beneficial for applications involving heavy industrial components, such as gas turbine blades weighing more than 15 lbs, and in certain embodiments, up to 55 lbs. The substantially uniform microstructure of Ni-base superalloys may enable reduced crack growth rates in heavy gas turbine blades, while the ability to maintain a high volume fraction of γ' phase in Ni-base superalloys contributes to the high strength of gas turbine blades in high temperature operating environments.

[0014] 1 illustrates exemplary components of a turbomachine, e.g., a rotating blade 100 of a type in which embodiments of the present disclosure may be employed. The turbine rotating blade 100 includes a root 102 at which the rotating blade 100 is attached to a rotor (not shown) of the turbomachine. The root 102 may include a dovetail 104 configured to fit into a corresponding dovetail slot in the rotor. The root 102 may further include a shank 106 extending between the dovetail 104 and a radially inner platform 108 disposed at the junction of an airfoil body 110 and the root 102 and defining a portion of the inner boundary of a flowpath through a turbine assembly (not shown) of the turbomachine. The airfoil body 110 is the active component of the rotating blade 100 that interrupts the flow of a working fluid and rotates a rotor disk. The airfoil body 110 of the rotating blade 100 is seen to include a concave pressure side (PS) outer wall 112 and a circumferentially or laterally opposed convex suction side (SS) outer wall 114 extending axially between opposed leading and trailing edges 116 and 118, respectively. The sidewalls 112 and 114 also extend radially from the turbomachine platform 108 to an outboard tip 120.

[0015] Figure 2 is a partial, enlarged cross-sectional view of the rotating blade 100 of Figure 1 taken along line 2-2. As shown in Figure 1, the body 110 of the blade 100 has a concave pressure side (PS) outer wall 112 and a convex suction side (SS) outer wall 114. Figure 2 further illustrates a body dimension 202 (e.g., thickness) of the article (e.g., blade 100) extending between a first sidewall (e.g., concave pressure side (PS) outer wall 112) and an opposite second sidewall (e.g., convex suction side (SS) outer wall 114). The body dimension 202 includes outer sections 204 and 206 adjacent to the sidewalls 112 and 114, respectively, each outer section 204 and 206 having a first dimension d1. Body dimension 202 further includes inner section 208 having a second dimension d2, and respective outer sections 204 and 206 and middle sections 210 and 212 adjacent inner section 208, each middle section 210 and 212 having a third dimension d3. In some embodiments, middle sections 210, 212 may be directly adjacent to respective outer sections 204 and 206 and may also be directly adjacent to inner section 208.

[0016] It should be understood that Figure 2 is used as a non-limiting example to illustrate that the body dimensions 202 of the article can be comprised of outer, inner, and middle sections. Dimensions d1, d2, and d3 are exaggerated and not drawn to scale with respect to Figure 1. Furthermore, dimensions d1, d2, and d3 are not limited to those depicted in Figure 2, and the ratios between dimensions d1, d2, and d3 can also vary. In embodiments, each of the outer sections 204 and 206 can have the same or different first dimension d1, and each of the middle sections 210 and 212 can have the same or different third dimension d3. The lines and / or boundaries and / or slopes between each section are depicted for illustrative purposes only and may not represent the physical presence of the lines and / or boundaries. In certain embodiments, outer sections 204 and 206, inner section 208, and middle sections 210 and 212 may form a continuous segment spanning body dimension 202 that is substantially free of cavities disposed within one or more of the outer, inner, and middle sections. In some embodiments, various now known or later developed forms and shapes of one or more hollow cooling passages may be disposed within one or more of the outer, inner, and middle sections. For example, the non-limiting example of cooling passage 122 as shown in FIG. 1 may be implemented within one or more of the outer, inner, and middle sections. The outer, inner, and middle sections may be formed from the same material. In some embodiments, body dimension 202 may be an axial dimension (e.g., width) extending axially between leading edge 116 and trailing edge 118 of blade 100 in FIG. 1 . The axial dimension may similarly be comprised of the outer section, the inner section, and the middle sections adjacent to each outer section and inner section. In certain embodiments, the body may be part of a turbine component selected from the group consisting of a shank, a bucket, a blade, a nozzle, a vane, a shroud, and any combination thereof.

[0017] In the present disclosure, it has been discovered that by developing nickel-base superalloys in which the parameters of the γ' grains are specifically controlled, a substantially uniform microstructure of the nickel-base superalloy can be achieved. For example, the body of an article prepared from such a nickel-base superalloy can have a substantially uniform microstructure throughout the body dimension of the article, across outer, inner, and middle sections (as shown in FIG. 2), as discussed in more detail below. This is particularly advantageous for articles having thick sections, e.g., the shank section of a turbine blade, where, when using conventional nickel-base superalloys, uniform heating and cooling in superalloy processing is not practical and the non-uniform superalloy microstructure with γ' grains can be susceptible to rafting.

[0018] Figures 3a-3c show micrographs of a portion of the microstructure of nickel-based superalloy I (the reference superalloy) in the article. In the micrographs, the light gray areas represent the γ matrix in the Ni-based superalloy I, and the dark black areas represent the γ' phase in the Ni-based superalloy I (more clearly indicated by the arrows in Figure 4b). A heterogeneous microstructure is observed in the reference nickel-based superalloy I, with more rafting occurring in both the inner section (Figure 3a) and the outer section (Figure 3c) than in the middle section (Figure 3b). Under the combined influence of stress and temperature, the initial γ' cubic grains can deform into plates, a phenomenon commonly referred to as rafting. In this embodiment, the γ' phase in the inner section (Figure 3a) and the outer section (Figure 3c) have different rafting profiles and / or orientations, and it can also be seen that the rafting in the inner and outer sections occurs in different directions. Without being bound by theory, it is believed that the non-uniform rafting of the gamma prime phase in nickel-base superalloys is a major factor in the high crack growth or rafting of articles prepared from nickel-base superalloys.

[0019] 4a-4c show micrographs of a portion of the microstructure of Ni-base superalloy II in an article according to an embodiment of the present disclosure. 5a-5c show micrographs of a portion of the microstructure of Ni-base superalloy III in an article according to an embodiment of the present disclosure. The nickel-base superalloy has a microstructure including a γ phase matrix (represented as the light gray region indicated by the arrows) and a γ' phase (represented as the dark black region indicated by the arrows) including a plurality of γ' particles dispersed in the gamma phase matrix. For superalloys II and III, a substantially uniform microstructure is observed throughout the body dimensions of the article body, for example, across the inner section ( FIGS. 4a and 5a ), middle section ( FIGS. 4b and 5b ), and outer section ( FIGS. 4c and 5c ) of the article body. In some embodiments, the γ' phase has a morphology profile that is substantially uniform between the middle section and at least one of the inner and outer sections. That is, unlike conventional nickel-base superalloys, superalloys according to embodiments of the present disclosure do not exhibit significant γ' phase morphology variation with location within the body of the article. Articles prepared from superalloy II or superalloy III exhibit reduced crack growth rates compared to articles prepared from reference superalloy I; for example, in certain embodiments, the rate of crack growth length over time can be at least 1000 times lower.

[0020] As used herein, the term "superalloy" refers to a material strengthened by precipitates dispersed in a matrix phase. Commonly known examples of superalloys include nickel-based superalloys strengthened by γ' precipitates dispersed in a gamma phase matrix (e.g., γ' precipitation strengthened nickel-based superalloys). The term "nickel-based" generally means that the composition has a greater abundance of nickel than any other constituent element. The terms "alloy," "superalloy," "nickel-based superalloy," and "γ' precipitation strengthened nickel-based superalloy" may be used interchangeably in this disclosure. In some embodiments, the nickel-based superalloy has a single-crystal grain microstructure.

[0021] Typically, in gamma prime precipitation strengthened nickel-base superalloys, one or more of chromium, tungsten, molybdenum, iron, and cobalt are the primary alloying elements that combine with nickel to form the gamma phase matrix. One or more of aluminum, titanium, tantalum, niobium, and vanadium are the primary alloying elements that combine with nickel to form the desired strengthening precipitates of the gamma prime phase, i.e., Ni3(Al,X), where X can be one or more of titanium, tantalum, niobium, and vanadium.

[0022] In certain embodiments of the present disclosure, the nickel-base superalloy includes at least 30 weight percent nickel, based on the weight percent of the superalloy. In embodiments, the Ni-base superalloy includes between about 4.0 weight percent and about 7.0 weight percent aluminum. For example, the weight percent of aluminum in the Ni-base superalloy can be between about 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, and 7.0, or within any two ranges exemplified herein. The Ni-base superalloy can include between 0 weight percent and about 2.0 weight percent niobium (Nb). For example, the weight percent of niobium in the Ni-base superalloy can be between about 0.1, 0.2, 0.5, 1.0, 1.5, and 2.0, or within any two ranges exemplified herein. In embodiments, the nickel-base superalloy can be substantially free of niobium. The Ni-base superalloy can include between about 4.0 weight percent and about 10.0 weight percent tantalum (Ta). For example, the weight percent of tantalum in the Ni-base superalloy can be about 4.0, 5.0, 5.5, 6.0, 7.0, 7.5, 8.0, 9.0, 10.0, or any range between any two of the values ​​exemplified herein. The Ni-base superalloy can include 0 weight percent to about 4.0 weight percent titanium (Ti). For example, the weight percent of titanium in the Ni-base superalloy can be about 0, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, or any range between any two of the values ​​exemplified herein. In embodiments, the Ni-base superalloy can be substantially free of titanium. In embodiments, the Ni-base superalloy can be substantially free of vanadium.

[0023] The Ni-base superalloy may further include additional elements. The Ni-base superalloy may include about 5.0 weight percent to about 25.0 weight percent chromium (Cr). For example, the weight percent of chromium in the Ni-base superalloy may be about 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 15.0, 20.0, or 25.0, or may be within a range between any two of the values ​​exemplified herein. The Ni-base superalloy may include 0 weight percent to about 20.0 weight percent cobalt (Co). For example, the weight percent of cobalt in the Ni-base superalloy may be about 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9, 9.5, 10.0, 15.0, or 20.0, or may be within a range between any two of the values ​​exemplified herein. The Ni-base superalloy may include 0 weight percent to about 3.0 weight percent hafnium (Hf). For example, the weight percent of hafnium in the Ni-base superalloy can be about 0, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, or any range between any two of the values ​​exemplified herein. The Ni-base superalloy can include 0 weight percent to about 4.0 weight percent molybdenum (Mo). For example, the weight percent of molybdenum in the Ni-base superalloy can be about 0, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, or any range between any two of the values ​​exemplified herein. The Ni-base superalloy can include 0 weight percent to about 6.0 weight percent rhenium (Re). For example, the weight percent of rhenium in the Ni-base superalloy may be about 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0, or may be within a range between any two of the values ​​exemplified herein. The Ni-base superalloy may include 4.0 weight percent to about 8.0 weight percent tungsten (W). For example, the weight percent of tungsten in the Ni-base superalloy may be about 4.0, 5.0, 6.0, 7.0, or 8.0, or may be within a range between any two of the values ​​exemplified herein. The Ni-base superalloy may optionally further include 0 weight percent to about 0.1 weight percent zirconium (Zr), 0 weight percent to about 0.2 weight percent carbon (C), and 0 weight percent to about 0.1 weight percent boron (B).The balance of the Ni-base superalloy is essentially nickel and unavoidable impurities.

[0024] In certain embodiments, the nickel-base superalloy comprises about 4.0 weight percent to about 7.0 weight percent aluminum, about 5.0 weight percent to about 10.0 weight percent chromium, about 6.0 weight percent to about 10.0 weight percent cobalt, 0 weight percent to about 1.5 weight percent hafnium, 0 weight percent to about 3.0 weight percent molybdenum, 0 weight percent to about 2.0 weight percent niobium, 0 weight percent to about 6.0 weight percent rhenium, about 4.0 weight percent to about 10.0 weight percent tantalum, 0 weight percent to about 4.0 weight percent titanium, about 4.0 weight percent to about 8.0 weight percent tungsten, and the balance essentially nickel and unavoidable impurities.

[0025] In a preferred embodiment, the nickel-base superalloy comprises about 6.0 weight percent to about 7.0 weight percent aluminum, about 5.0 weight percent to about 7.0 weight percent chromium, about 6.5 weight percent to about 8.5 weight percent cobalt, about 0.1 weight percent to about 0.2 weight percent hafnium, about 1.0 weight percent to about 2.0 weight percent molybdenum, 0 weight percent to about 3.5 weight percent rhenium, about 5.5 weight percent to about 7.5 weight percent tantalum, about 5.0 weight percent to about 7.0 weight percent tungsten, and the balance essentially nickel and unavoidable impurities.

[0026] In certain embodiments, the Ni-base superalloy can include a base alloy, which can be one or more of CMSX 4, TMS 75, TMS 82, Rene N2, Rene N5, Rene N6, Rene N500, Rene N515, or PWA 1484. These base alloys are well known to those skilled in the art.

[0027] As used herein and throughout this disclosure, the term "substantially free" when used in conjunction with a particular element means that the Ni-base superalloy contains between 0 weight percent and about 0.1 weight percent of such particular element. For example, "substantially free of niobium" may include embodiments in which the Ni-base superalloy contains no niobium, or less than about 0.1 weight percent niobium, or between 0 weight percent and about 0.1 weight percent niobium.

[0028] The term "weight percent" of a particular element in a Ni-base superalloy, as used herein and throughout this disclosure, refers to the weight percent of such particular element in the Ni-base superalloy based on the total weight of the Ni-base superalloy.

[0029] As explained in the previous section, nickel-base superalloys have a microstructure that may include a gamma phase matrix and a gamma prime phase having a plurality of rafting-resistant gamma prime grains precipitated in the gamma phase matrix.

[0030] γ' grains typically have an ordered face-centered cubic L12 structure. For example, Figure 6 shows a representative crystal structure of γ' grains in a Ni3Al alloy, where the γ' grains have a cubic P (simple cubic) lattice with nickel atoms in the face centers and aluminum (Al) atoms at the cube corners. Other alloys, such as Ni3Ti or Ni3(Al,Ti), may have a similar structure in which aluminum atoms are partially or totally replaced by titanium atoms. In addition to aluminum and titanium, niobium, hafnium, and tantalum may also preferentially partition into the γ' phase. As discussed above, γ' grains can act as strengtheners, providing Ni-base superalloys with desirable high-temperature properties, such as high strength in high-temperature operating environments. As used herein, the term "high temperature" refers to temperatures above 1000°F. In some embodiments, high temperature refers to the operating temperature of an article, e.g., a turbine engine.

[0031] Without being bound by theory, it is hypothesized that under certain conditions, atomic rearrangements can occur within the face-centered cubic L12 structure of the γ' grains, leading to γ' phase or γ' grain rafting and crack growth in nickel-based superalloys having such γ' phase.

[0032] It was discovered that Ni-base superalloys can be developed with controlled parameters of the gamma prime grains in their microstructure, resulting in significantly improved Ni-base superalloys with rafting-resistant gamma prime grains and reduced crack growth. As previously mentioned, in conventional approaches, the volume fraction of the γ' phase in Ni-base superalloys is reduced to reduce rafting, for example, by reducing the weight percent of aluminum in the Ni-base superalloy. In contrast, in the present disclosure, the desired high volume fraction of the strengthening γ' phase in the Ni-base superalloy need not be reduced, thus achieving the goal of reducing detrimental crack growth while maintaining the high strength of the Ni-base superalloy. Accordingly, the γ' grains and γ' phase of the present disclosure may also be referred to as "rafting-resistant γ' grains" and / or "rafting-resistant γ' phase," which are used interchangeably throughout this disclosure. The microstructure of a Ni-base superalloy that includes rafting-resistant γ' grains may be referred to as a "rafting-resistant microstructure."

[0033] In certain embodiments, an article is provided having a body comprising a nickel-base superalloy. The body has a first sidewall, a second sidewall opposite the first sidewall, and a body dimension extending between the first and second sidewalls. The body further comprises a nickel-base superalloy having a microstructure comprising a gamma matrix and a gamma prime phase including a plurality of rafting-resistant gamma prime particles dispersed in the gamma matrix. The plurality of gamma prime particles have an average perimeter of about 3 microns to about 15 microns and an average aspect ratio of about 1.2 to about 3, and the nickel-base superalloy microstructure is substantially uniform throughout the body dimension. In embodiments, the average perimeter of the plurality of gamma prime particles for a particular portion or region of interest (ROI) in the nickel-base superalloy microstructure can be measured by first taking multiple images at the selected ROI of the microstructure. Next, using analytical equipment such as a scanning electron microscope (SEM), each of the multiple images can be converted into a two-tone image (e.g., black and white) that highlights only the γ matrix and γ' phase (e.g., as shown in Figure 4b, where a representative image of the γ matrix and γ' phase is indicated by the arrows). Now-known or later-developed computer image analysis software can be used to average the widths and heights of the multiple γ' phase particles and further provide an average perimeter for the multiple γ' phase particles. For example, in some embodiments, Image J, an open-source image processing program developed by the National Institutes of Health, can be used as the computer image analysis software.

[0034] It should be understood that SEM is described herein as a non-limiting example. Superalloy microstructures can be analyzed and / or characterized in photomicrographs obtained by any currently known or future-developed technique, including, but not limited to, optical microscopy (OM). Samples imaged with an SEM can be polished and etched using standard metallurgical laboratory techniques. Image analysis can be performed on the photomicrographs using any currently known or future-developed imaging software to quantitatively characterize multiple rafting-resistant gamma prime grain parameters in the microstructure, including, but not limited to, grain size, grain perimeter, aspect ratio, spacing between adjacent gamma prime grains, volume fraction, and corresponding average values ​​of any of these parameters. The volume fraction of γ' phase in Ni-base superalloys can be characterized by measuring the area fraction of γ' phase using the image analysis methods described herein. As used herein and throughout the specification, the term "volume fraction" of γ' phase in Ni-base superalloys refers to the volume percent (% v / v) of γ' grains in the total volume of the Ni-base superalloy. Methods for characterizing the volume fraction and / or area fraction of γ' phase are known to those skilled in the art. For example, the area fraction of γ' phase can be characterized by dividing the sum of the measured areas of multiple images of γ' grains within an ROI by the total area of ​​the ROI in the microstructure of a Ni-base superalloy. In some embodiments, the value of the area fraction of γ' phase can be used as a surrogate for the value of the volume fraction of γ' phase. In embodiments, the value of the area fraction of γ' phase can be the same as the value of the volume fraction of γ' phase. As used herein and throughout this description, the aspect ratio of a γ' grain can generally refer to the ratio of the major dimension to the minor dimension of a γ' grain. The average aspect ratio of a plurality of γ' grains can be obtained by measuring the aspect ratio of each individual γ' grain of the plurality of γ' grains and averaging the aspect ratio measurements of the individual γ' grains.

[0035] In certain embodiments, the plurality of rafting-resistant γ' particles can have controlled parameters, including, but not limited to, an average particle perimeter in the range of about 2.0 microns to about 25.0 microns. For example, the average particle perimeter can be about 2.0 microns, about 3.0 microns, about 4.0 microns, about 5.0 microns, about 6.0 microns, about 7.0 microns, about 8.0 microns, about 9.0 microns, about 10.0 microns, about 15.0 microns, about 20.0 microns, or about 25.0 microns, or any range between any two of the values ​​exemplified herein. In some embodiments, the average particle perimeter can be in the range of about 3.0 to about 20.0 microns, about 3.0 to about 15.0 microns, about 3.0 to about 10.0 microns, about 3.0 to about 7.0 microns, about 4.0 to about 15.0 microns, about 4.0 to about 10.0 microns, or about 7.0 to about 12.0 microns.

[0036] In some embodiments, the plurality of rafting-resistant γ' particles can have an average aspect ratio (AR) ranging from about 0.5 to about 3.0. For example, the average aspect ratio (AR) can be 0.5, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, and 3.0, or can be within a range between any two of the values ​​exemplified herein. In embodiments, the average aspect ratio (AR) can be in the range of about 1.5 to about 3.0, about 1.5 to about 2.5, about 1.5 to about 2.2, or about 1.2 to 3.0.

[0037] In embodiments, the rafting-resistant γ' particles of the present disclosure may have an average particle size of about 1.0 microns to about 6.0 microns. For example, the average particle size may be about 1.0 microns, about 1.5 microns, about 2.0 microns, about 2.5 microns, about 3.0 microns, about 3.5 microns, about 4.0 microns, about 4.5 microns, about 5.0 microns, about 5.5 microns, or about 6.0 microns, or may be within a range between any two of the values ​​exemplified herein. In embodiments, the average particle size may be in the range of about 1.0 microns to about 5.0 microns, the range of about 1.0 microns to about 4.0 microns, or the range of about 1.5 microns to about 5.0 microns.

[0038] In certain embodiments, the rafting-resistant γ' phase may be present in at least 40 volume percent of the Ni-base superalloy. For example, the rafting-resistant γ' phase may be present in about 50 volume percent, about 55 volume percent, about 60 volume percent, about 65 volume percent, about 70 volume percent, about 75 volume percent, or within a range between any two of the volumes exemplified herein. In embodiments, the γ' phase may be present in about 55 volume percent to about 75 volume percent of the superalloy. Furthermore, it should be understood that the terms "gamma prime phase," "γ' phase," "gamma prime grain," "γ' grain," "rafting-resistant γ' phase," and "rafting-resistant γ' grain" may be used interchangeably throughout this disclosure.

[0039] FIG. 7 shows a comparison of the average aspect ratios (AR) of γ' grains for Ni-base superalloys I, II, and III for the inner (a), middle (b), and outer (c) sections of the body of an article with the corresponding superalloy according to an embodiment of the present disclosure. It can be seen that the average AR of the γ' grains is substantially uniform across the entire body dimensions across the various sections in the articles prepared from superalloys II and III. In contrast, significant non-uniformity is observed in the article prepared from reference superalloy I; e.g., the average aspect ratio differs significantly between the middle section and at least one of the inner and outer sections of the article. Note that superalloys I, II, and III in FIG. 7 are the same as superalloys I, II, and III used in FIGS. 3a-3c, respectively, and throughout the remainder of this disclosure.

[0040] FIG. 8 shows a comparison of the average grain size of γ' grains for Ni-base superalloys I, II, and III for the inner (a), middle (b), and outer (c) sections of the body of an article with the corresponding superalloy according to an embodiment of the present disclosure. It can be seen that the average grain size of the γ' phase is substantially uniform across the entire body dimension across the various sections of the articles prepared from superalloys II and III. In contrast, significant non-uniformity is observed in the article prepared from reference superalloy I; for example, the average grain size differs significantly between the middle section and at least one of the inner and outer sections of the article.

[0041] As used herein and throughout the specification, the term "substantially uniform" means not deviating by more than + / - 10% from a measured value. For example, the measured average aspect ratio (AR) of the γ' grains is substantially uniform between the midsection and at least one of the inner and outer sections, meaning that the measured average aspect ratio (AR) for the midsection does not deviate by more than + / - 10% from the measured aspect ratio for the inner or outer sections. In some embodiments, the microstructure of the nickel-base superalloy is substantially uniform throughout the bodily dimension of the body, the microstructure comprising a plurality of rafting-resistant gamma prime grains, one or more parameters of which measurements at locations in the body do not deviate by more than + / - 10% from measurements taken from the remaining locations throughout the bodily dimension of the body. In other words, the microstructure comprises at least one parameter having a measurement that is substantially location-independent. For example, one or both of the average grain perimeter and average aspect ratio of the plurality of gamma prime grains have measurements that are substantially uniform throughout the microstructure of the nickel-base superalloy.

[0042] Referring now to FIG. 9 , a scatter plot of the measured average aspect ratio (AR) versus the measured average grain perimeter for superalloys I, II, and III is presented for the inner section (a), middle section (b), and outer section (c) of the body of the article having the corresponding superalloy. For the article prepared from reference superalloy I, the heterogeneous microstructure of the superalloy is again observed, with the γ′ grains in the middle section being in region A and substantially free of rafted γ′ grains, while the γ′ grains in the inner and outer sections fall primarily into region B, the rafted γ′ phase region. In contrast, the articles comprising superalloys II and III are substantially free of rafted γ′ grains throughout the entire body dimension of the article, including the inner, outer, and middle sections (see regions A and C). According to the present disclosure, γ′ phase rafting can be characterized by certain parameters of the γ′ article, such as the average aspect ratio and / or the average grain perimeter. In some embodiments, the plurality of rafting-resistant gamma prime particles can have an average particle perimeter of from about 3.0 microns to about 15.0 microns and an average aspect ratio of from about 1.2 to about 3.0.

[0043] Conventional approaches strive to produce γ' grains with a fine average size (typically less than 0.7 microns) or average grain perimeter, because such γ' grains are believed to provide desirable strengthening effects in superalloys. Without being bound by theory, the present disclosure hypothesizes that γ' grains with a fine average size tend to adopt a cubic configuration, which may lower the energy barrier for atomic dislocation / migration / displacement and promote more rapid rafting formation. Rafting poses significant challenges, for example, in applications involving gas turbine components or articles with large masses (e.g., greater than about 15 lb) and / or large internal cooling passages (e.g., serpentine-cooled investment castings). Similar challenges may exist in other applications involving heavy components with complex shapes and / or segments exposed to non-uniform heating / cooling. The present disclosure further hypothesizes that Ni-base superalloys with a rafting-resistant γ' phase and reduced crack growth can be developed by controlling the parameters of the γ' grains in the microstructure to a specific configuration. For example, by controlling the parameters of the γ' particles, including but not limited to, the average aspect ratio and average particle perimeter, the γ' particles of the present disclosure can be configured to adopt a more irregular and coarser γ' configuration, which deviates from the more regular cubic configuration with very small average particle size and / or perimeter (e.g., typically less than 1.0 micron). The approach of the present disclosure significantly prevents rafting in articles, including articles exposed to non-uniform heating / cooling.

[0044] 10a-10d show representative, non-limiting examples of micrographs with measured parameters of γ′ grains including an average perimeter of about 2.1 microns ( FIG. 10a ), an aspect ratio AR of about 7.0 ( FIG. 10b ), a perimeter of about 11.5 microns and an aspect ratio AR of about 1.2 ( FIG. 10c ), and a perimeter of about 25.0 microns ( FIG. 10d ) for corresponding Ni-base superalloys.

[0045] FIG. 11 shows a comparison of crack growth length over time between an article prepared using a conventional nickel-base superalloy (Reference Superalloy I) and an article prepared using the nickel-base superalloy II of the present disclosure. A significant reduction in crack growth rate for the article prepared using the nickel-base superalloy II of the present disclosure is observed, for example, when the article's operating time exceeds a certain operating period, e.g., 1000 hours. Note that FIG. 11 shows a non-limiting example, and the operating times shown are representative of the article under certain test conditions and are not considered limiting. The number or duration of the article's operating hours can be controlled by adjusting the chemistry, parameters of the γ' grain of the superalloy, and / or test conditions.

[0046] As discussed in the previous section, a conventional approach to reducing crack growth in articles prepared from nickel-base superalloys has been to obtain fine γ' grains and a reduced volume percentage of the γ' phase in the nickel-base superalloy. To achieve this, conventional processes focus on developing cooling rates after heating a workpiece having a nickel-base superalloy to a peak temperature above the solvus temperature of the γ' phase. For example, in a conventional process for forming γ' phase in a workpiece having a nickel-base superalloy, the workpiece is heated above the γ' solvus temperature of the nickel-base superalloy and the heat-treated workpiece is cooled at a rapid cooling rate to obtain fine circumferential γ' grains (typically less than 1 micron). It is hypothesized that the combination of heating above the γ' solvus temperature and a rapid cooling rate produces fine circumferential γ' grains, which adopt an ordered face-centered cubic microstructure and may contribute to the high strength of an article containing the workpiece. For example, this process may involve providing a workpiece having a nickel-base superalloy at a gamma prime solvus temperature of about 2320 degrees Fahrenheit (°F), heating the workpiece above the gamma prime solvus temperature at a heating rate of 25 degrees Fahrenheit per minute (°F / min) or greater, holding the workpiece at 2320°F for about two hours, and then cooling the workpiece to below 1200°F at a cooling rate of 75 degrees Fahrenheit per minute (°F / min) or greater. However, as noted above, while gamma prime prepared by conventional processes may have fine perimeter gamma prime grains that can provide a strengthening effect to the Ni-base superalloy, conventional gamma prime grains tend to form rafted gamma prime grains, which can lead to more crack growth in the article over time. The conventional approach may result in a detrimental microstructure when the article is fully processed, leading to a reduction in important mechanical properties such as fatigue performance and resistance to static crack growth.

[0047] In contrast, in processes according to embodiments of the present disclosure, the solution treatment is modified, for example, by modifying the peak temperature, the heat treatment rate, and / or the cooling rate. For example, the solution treatment peak temperature is significantly lower than the γ' solvus temperature, and the cooling rate is significantly reduced compared to conventional fast cooling rates. In some embodiments, instead of heating the workpiece above the γ' solvus temperature of the nickel-base superalloy, the workpiece can be heat treated below the γ' solvus temperature.

[0048] 12 is a flowchart illustrating a method for preparing an article from a workpiece having a body comprising a Ni-base superalloy according to an embodiment of the present disclosure. In a non-limiting example, a method for preparing an article from a workpiece having a body comprising a nickel-base superalloy is provided. The method includes providing a workpiece having a body comprising a nickel-base superalloy (S1002), heating the workpiece to a subsolvus temperature at a heat treatment rate (S1004), holding the workpiece at the subsolvus temperature for a predetermined heat treatment time (S1006), and cooling the workpiece from the subsolvus temperature at a cooling rate of less than about 75°F / min for a predetermined cooling time to produce the article (S1008). In certain embodiments, the cooling rate is less than about 75°F / min, less than about 65°F / min, less than about 55°F / min, less than 35°F / min, less than 25°F / min, less than about 20°F / min, or less than about 10°F / min, or may range between any two of the values ​​disclosed herein, for example, between about 10°F / min and about 20°F / min. As used herein and throughout this disclosure, a subsolvus temperature is a temperature below the γ' solvus temperature of the nickel-base superalloy. In embodiments, the method may further include controlling the cooling rate to less than about 10°F / min.

[0049] The method can further include adjusting one or both of the heat treatment rate and the cooling rate to control the formation of a nickel-base superalloy microstructure comprising a gamma phase matrix and a gamma prime phase comprising a plurality of rafter-resistant gamma prime particles dispersed in the gamma phase matrix, wherein the plurality of rafter-resistant gamma prime particles can have an average perimeter of about 3.0 microns to about 15.0 microns and an average aspect ratio of about 1.2 to about 3.0, and the nickel-base superalloy microstructure is substantially uniform throughout the body.

[0050] The resulting articles according to embodiments of the present disclosure may have a substantially uniform microstructure of the Ni-base superalloy across various sections of the body of the article, for example, an inner section, an outer section, and a middle section adjacent to the inner and outer sections of the body dimension of the article prepared from the nickel-base superalloy.

[0051] In a non-limiting example, the process of the present disclosure may include providing a workpiece having a nickel-base superalloy at a gamma prime solvus temperature of about 2320 degrees Fahrenheit (°F); heating the workpiece at a predetermined heating rate, for example, at least 25 degrees Fahrenheit per minute (°F / min), to below the gamma prime solvus temperature of about 2220 degrees Fahrenheit (°F); and holding the workpiece at 2220°F for about two hours, followed by cooling the workpiece at a cooling rate of no more than 75 degrees Fahrenheit per minute (°F / min) to below 1200°F. For the same nickel-base superalloy used in the conventional process described above, the temperature below the gamma prime solvus temperature may range from about 2000°F to about 2250°F. In certain embodiments, the cooling rate may be less than about 75°F / min, less than about 65°F / min, less than about 55°F / min, less than 35°F / min, less than 25°F / min, less than about 20°F / min, or less than about 10°F / min, or may range between any two of the values ​​disclosed herein, e.g., between about 10°F / min and about 20°F / min. It is understood that certain process parameters, such as solvus temperature, heating rate, and / or cooling rate, may vary and may depend on the composition of each individual nickel-base superalloy. Such variations in process parameters are intended to be within the scope of the present disclosure.

[0052] In an embodiment, the providing step of the process shown in FIG. 12 may further include providing a nickel-base superalloy that includes, in weight percent of the nickel-base superalloy, about 4.0 weight percent to about 7.0 weight percent aluminum (Al), about 5.0 weight percent to about 10.0 weight percent chromium (Cr), about 6.0 weight percent to about 10.0 weight percent cobalt (Co), 0 weight percent to about 1.5 weight percent hafnium (Hf), 0 weight percent to about 4.0 weight percent molybdenum (Mo), 0 weight percent to about 2.0 weight percent niobium (Nb), 0 weight percent to about 6.0 weight percent rhenium (Re), about 4.0 weight percent to about 10.0 weight percent tantalum (Ta), 0 weight percent to about 4.0 weight percent titanium (Ti), about 4.0 weight percent to about 8.0 weight percent tungsten (W), and the balance Ni and unavoidable impurities.

[0053] In certain embodiments, the rafting-resistant gamma prime phase is present in about 55 volume percent (% v / v) to about 75 volume percent (% v / v) of the total volume of the superalloy. In some embodiments, the body has a weight of about 15 pounds or more. In embodiments, the body has a weight in the range of about 15 pounds to about 55 pounds.

[0054] The term "workpiece," as used herein, refers to an initial article prepared from a starting material by a solidification process, e.g., investment casting, by pouring liquid metal into a ceramic mold under vacuum followed by gradual solidification. The workpiece may be prepared by any now known or later developed technique, e.g., thermomechanical or powder metallurgical processing followed by mechanical working, to provide the nickel-base superalloy described herein.

[0055] In an alternative embodiment, the nickel-base superalloy can be subjected to a solution treatment followed by an aging heat treatment. The solution treatment can be a subsolvus or supersolvus solution treatment. The solution treatment can be performed under controlled heating and / or controlled cooling in an argon atmosphere to minimize oxidation. In a supersolvus solution treatment, the γ' grains are dissolved, while in a subsolvus solution treatment, the γ' grains are pinned at the grain boundaries, limiting grain growth.

[0056] It should be understood that the exemplary methods for preparing articles as set forth herein are not intended to be limiting. Other methods and processes can be used to obtain articles from workpieces having bodies comprising nickel-base superalloys of particular properties. Such modifications and variations are intended to be within the scope of this disclosure.

[0057] The disclosed process provides a novel Ni-base superalloy having a microstructure of multiple rafter-resistant γ' grains with controlled parameters. The rafter-resistant γ' grains have specific parameters controlled within specific ranges, and the γ' phase is substantially free of rafting. The adjustable parameters of the γ' grains may include, but are not limited to, grain perimeter, aspect ratio, grain size, spacing between adjacent γ' grains, including the average value of each specific parameter, or any combination thereof. A substantially uniform morphology profile of the γ' phase can be achieved across various sections of the body dimension of an article prepared from the nickel-base superalloy, which is advantageous for certain industrial components, such as gas turbine blades weighing 15 lbs or more. Furthermore, the goal of reducing crack growth is achieved while maintaining a high volume fraction of the strengthening γ' phase in the nickel-base superalloy.

[0058] The above figures illustrate some of the processes involved in some embodiments of the present disclosure. In this regard, each figure or block within the flow diagrams of the figures represents a process associated with the described method embodiment. It should also be noted that in some alternative implementations, the operations described in the figures or blocks may occur out of the order shown in the figures, or may actually be performed substantially simultaneously or in reverse order, depending on the operations involved, for example. Those skilled in the art will also recognize that additional blocks describing the processes may be added.

[0059] As used herein throughout this specification and claims, approximation language can be applied to modify any quantitative expression that can reasonably vary without resulting in a change in the basic function involved. Thus, values ​​modified by terms such as "approximately," "about," and "substantially" are not limited to the exact value specified. In at least some instances, approximation language can correspond to the precision of the instrument used to measure the value. Here, and throughout this specification and claims, range limitations are combinable and / or interchangeable, and unless the context and language dictate otherwise, such ranges are identified and include all subranges encompassed therein. "Approximately," "about," and "substantially," when applied to a particular value or a range that includes a starting and ending value, can include + / - 10% of the particular value or the starting and ending values ​​of the range, unless dependent on the precision of the instrument used to measure the values.

[0060] The corresponding structure, material, acts, and equivalents of all means-plus-function or step-plus-function elements in the following claims are intended to encompass any structure, material, or acts for performing that function in combination with other specifically claimed claim elements. The description of the present disclosure has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The present embodiments were chosen and described in order to best explain the principles and practical application of the disclosure and to enable others skilled in the art to understand the disclosure in its various embodiments with various modifications as suited to the particular uses envisioned. [Explanation of symbols]

[0061] 100 Turbine Rotating Blades 102 base 104 Dovetail 106 Shank 108 Platform 110 Airfoil body 112 Concave pressure side (PS) outer wall 114 Convex suction side (SS) outer wall 116 leading edge 118 Trailing edge 120 Outer tip 122 Cooling passage 202 Body dimensions 204 Outer Section 206 Outer Section 208 Inner Section 210 Mid Section 212 Mid Section 1002 steps 1004 steps 1006 steps 1008 steps 2-2 line d1 first dimension d2 Second dimension d3 third dimension

Claims

1. A body (110) having a first sidewall (112), a second sidewall (114) opposite the first sidewall (112), and a body dimension (202) extending between the first sidewall (112) and the second sidewall (114), the body (110) being comprised of a nickel-base superalloy having a microstructure, the microstructure comprising: a gamma phase matrix; a gamma prime phase consisting of a plurality of rafter-resistant gamma prime particles dispersed in the gamma phase matrix, the plurality of rafter-resistant gamma prime particles having an average particle perimeter of 3.0 μm to 15.0 μm and an average aspect ratio of 1.2 to 3.0, the gamma prime phase being present in at least 40 volume percent of the nickel-base superalloy, and wherein both the measured average particle perimeter and the measured average aspect ratio of the plurality of rafter-resistant gamma prime particles do not deviate by more than ±10% throughout the body dimension (202) of the body (110); A body (110) including An article comprising: % to 4.0 wt. % aluminum (Al), 5.0 wt. % to 10.0 wt. % chromium (Cr), 6.0 wt. % to 10.0 wt. % cobalt (Co), 0 wt. % to 1.5 wt. % hafnium (Hf), 0 wt. % to 4.0 wt. % molybdenum (Mo), 0 wt. % to 2.0 wt. % niobium (Nb), 0 wt. % to 6.0 wt. % rhenium (Re), 4.0 wt. % to 10.0 wt. % tantalum (Ta), 0 wt. % to 4.0 wt. % titanium (Ti), 4.0 wt. % to 8.0 wt. % tungsten (W), and the balance Ni and unavoidable impurities.

2. The article of claim 1, wherein the body (110) weighs 15 pounds or more.

3. The article of claim 1, wherein the body (110) has a weight in the range of 6.8 kg to 25 kg (15 lbs to 55 lbs).

4. The article of any one of claims 1 to 3, wherein the gamma prime phase is present at 55% to 75% by volume (% v / v) of the superalloy.

5. The article of any one of claims 1 to 4, wherein the plurality of rafting resistant gamma prime particles have an average particle size of 1.0 µm to 6.0 µm.

6. The article of any one of claims 1 to 5, wherein the nickel-base superalloy comprises a single crystal grain microstructure.

7. 7. The article of any one of claims 1 to 6, wherein the nickel-base superalloy consists essentially of 4.0 to 7.0 wt.% aluminum (Al), 5.0 to 7.0 wt.% chromium (Cr), 6.5 to 8.5 wt.% cobalt (Co), 0.1 to 0.2 wt.% hafnium (Hf), 1.0 to 2.0 wt.% molybdenum (Mo), 0 to 3.5 wt.% rhenium (Re), 5.5 to 7.5 wt.% tantalum (Ta), 5.0 to 7.0 wt.% tungsten (W), and the balance being nickel and incidental impurities.

8. The article of any one of claims 1 to 7, wherein the body (110) is part of a turbine component.

9. The article of any one of claims 1 to 8, wherein the body (110) does not include any voids within the body dimension (202).

10. A nickel-base superalloy comprising, in weight percent of said nickel-base superalloy: 4.0 wt% to 7.0 wt% aluminum (Al), 5.0 wt% to 10.0 wt% chromium (Cr), 6.0 wt% to 10.0 wt% cobalt (Co), 0 wt% to 1.5 wt% hafnium (Hf), 0 wt% to 3.0 wt% molybdenum (Mo), 0 wt% to 2.0 wt% niobium (Nb), 0 wt% to 6.0 wt% rhenium (Re), 4.0 wt% to 10.0 wt% tantalum (Ta), 0 wt% to 4.0 wt% titanium (Ti), 4.0 wt% to 8.0 wt% tungsten (W), and the balance being Ni and unavoidable impurities. It consists of The nickel-base superalloy has a microstructure comprising: a gamma phase matrix; a gamma prime phase consisting of a plurality of rafting-resistant gamma prime particles dispersed in the gamma phase matrix, the plurality of rafting-resistant gamma prime particles having an average particle perimeter of 3.0 μm to 15.0 μm and an average aspect ratio of 1.2 to 3.0; having a microstructure comprising 1. A nickel-base superalloy, wherein the gamma prime phase is present in at least 40 volume percent of the nickel-base superalloy, and wherein both the average grain perimeter and the average aspect ratio of the plurality of rafting resistant gamma prime grains do not vary by more than ±10% throughout the microstructure of the nickel-base superalloy.

11. The nickel-base superalloy of claim 10, wherein the gamma prime phase is present in between 55% by volume (% v / v) and 75% by volume (% v / v) of the superalloy.

12. The nickel-base superalloy of claim 10 or claim 11, wherein the plurality of rafting resistant gamma prime grains have an average grain size of 1.0 μm to 6.0 μm.

13. 13. The nickel-base superalloy of any one of claims 10 to 12, comprising a single crystal grain microstructure.

Images