Patent Description:
Some articles formed from superalloys include a single crystal and are formed using casting. When forming articles that are relatively large or include a relatively complex geometry, casting a single crystal may be difficult, leading to relatively high rejection rates due to defects in the cast article. For example, nozzle guide vanes for gas turbine engines may be cast as a single crystal, and this may restrict design complexity of the nozzle guide vanes.

<CIT> discloses a process for repairing a turbine component of a turbomachine, as well as a sintered preform used in the process and a high gamma-prime nickel-base superalloy component repaired thereby. The sintered preform contains a sintered mixture of powders of a cobalt-base braze alloy and a cobalt-base wear-resistant alloy. The braze alloy constitutes at least about <NUM> up to about <NUM> weight percent of the sintered preform and contains a melting point depressant such as boron. The preform is formed by mixing powders of the braze and wear-resistant alloys to form a powder mixture, and then sintering the powder mixture. To use the preform, a surface portion of the turbine component is removed to expose a subsurface portion, followed by diffusion bonding of the preform to the subsurface portion to form a wear-resistant repair material containing the braze alloy dispersed in a matrix of the wear-resistant alloy.

<CIT> discloses nickel base superalloy single crystal articles formed of a particular composition and heat treated. The resultant articles are substantially free from the grain boundary strengtheners such as carbon, boron, and zirconium and contain only a limited amount of cobalt. As a result of the alloy composition, the alloys have a high incipient melting temperature. The heat treatment process homogenizes the microstructure, and refines the gamma prime morphology.

<NPL>, discloses nickel-based superalloys for use in gas-turbine engines.

<CIT> discloses a method of making a braze preform that includes: providing a mixture of a brazing alloy in metallic powder form and a binder; melting the binder and forming the mixture into a preform having a preselected shape; removing a majority of the binder from the preform; and heating the preform to remove the remainder of the binder and to sinter the metallic powder together. The preform may include a wear-resistant material therein. Such preforms may be used to form a braze joint between two metallic components, or to produce a metallic component with a wearcoated surface. <CIT> discloses a method for repairing a damaged portion of a gas turbine blade comprising: providing a preform comprising a low-melt alloy material and a base alloy material; locating the preform on the gas turbine engine blade damaged portion; and heat treating the preform and the blade such that the preform is brazed to the blade. The method involves providing a preform comprising <NUM> to <NUM> % by weight base alloy material and <NUM> to <NUM> % by weight low-melt allow material based on the total weight of the preform before heat treatment.

Viewed from a first aspect, there is provided a method as defined in claim <NUM> of the appended claims.

Viewed from a second aspect, there is provided an assembly as defined in claim <NUM> of the appended claims.

The method includes positioning a first component comprising a first metal or alloy and a second component comprising a second metal or alloy to each other to define a joint region between adjacent portions of the first component and the second component. The method also includes positioning a pre-sintered preform (PSP) braze material in the joint region. The PSP braze material includes a wide gap braze material as defined in claim <NUM>. The method further includes heating the PSP braze material to form a molten braze alloy and cooling the molten braze alloy to join the first and second components.

The disclosure also describes an assembly that includes a first component comprising a first metal or alloy and a second component comprising a second metal or alloy. The first component and second component are positioned adjacent to each other to define a joint region between adjacent portions of the first component and the second component. The assembly also includes a pre-sintered preform (PSP) braze material as defined in claim <NUM> disposed in the joint region and a heat source for heating the PSP braze material disposed in the joint region.

The disclosure describes assemblies, systems, and techniques for joining a first component including a metal or alloy and a second component including a metal or alloy using a pre-sintered preform (PSP) braze material. The PSP braze material includes a wide gap braze material, and may include a powder that has been sintered to reduce porosity. The wide gap braze material is a Ni-based wide gap braze material.

In some examples, braze foils have been formed using a melting spinning technique, which results in thin foils having an amorphous microstructure. Although melting spinning is suitable for many braze alloys, some of these braze alloys may possess mechanical and chemical properties (e.g., mechanical strength and high temperature oxidation resistance) that make the braze alloys unsuitable for use in high temperature oxidative environments. In contrast, the PSP braze materials described herein may, after brazing, result in alloys that have properties suitable for use in high temperature oxidative environments.

The PSP braze materials are nickel-based alloys. The PSP braze materials may be used to join components that include a Ni-based alloy or a Co-based alloy.

Because the PSP braze materials may possess mechanical and chemical properties (e.g., mechanical strength and high temperature oxidation resistance) that make the braze alloys suitable for use in high temperature oxidative environments, the PSP braze materials may facilitate manufacture of articles for high temperature mechanical systems in multiple components, which are then joined using the PSP braze materials. This may reduce cost of manufacture due to lower defect levels in the components, facilitate more complex geometry, or the like. In some examples, the PSP braze materials also may provide advantages compared to powder braze materials. For example, the PSP braze materials may result in reduced porosity in the braze joint compared to braze joints formed using a powder, which may improve mechanical properties of the braze joint. Further, the PSP braze materials may be easier to position in the joint region and result in a more uniform braze joint.

<FIG> is a conceptual and schematic diagram illustrating an example assembly <NUM> for joining a first component <NUM> including a metal or alloy and a second component <NUM> including a metal or alloy using a pre-sintered preform (PSP) braze material <NUM>. In some examples, first component <NUM> and second component <NUM> may be joined to form an article or a portion of an article that is part of a high temperature mechanical system. For example, first component <NUM> and second component <NUM> may be joined to form an article or a portion of nozzle guide vane (NGV) that is used in a high pressure or intermediate pressure stage in a gas turbine engine. In other examples, the article may include another component of a high temperature mechanical system, such as another component of a gas turbine engine. For example, the article may include a gas turbine engine blade, gas turbine engine vane, blade track, combustor liner, or the like.

Each of first component <NUM> and second component <NUM> includes a metal or alloy. In some examples, first component <NUM> and second component <NUM> include substantially the same (e.g., the same or nearly the same) metal or alloy. In other examples, first component <NUM> and second component <NUM> include different metals or alloys. In some examples, each of first component <NUM> and second component <NUM> may include a Ni-, Co-, Fe-based superalloy, or the like. First component <NUM> and second component <NUM> including a superalloy may include other additive elements to alter its mechanical and chemical properties, such as toughness, hardness, temperature stability, corrosion resistance, oxidation resistance, and the like, as is known in the art. Any useful superalloy may be utilized in first component <NUM> and second component <NUM>, including, for example, Ni-based alloys available from Martin-Marietta Corp. , Bethesda, MD, under the trade designation MAR-M246, MAR-M247; Ni-based alloys available from Cannon-Muskegon Corp. , Muskegon, MI, under the trade designations CMSX-<NUM>, CMSX-<NUM>, CMSX-<NUM>, and CM-<NUM>; Co-based alloys available from Martin-Marietta Corp. , Bethesda, MD, under the trade designation MAR-M509; and the like. The compositions of CMSX-<NUM> and CMSX-<NUM> are shown below in Table <NUM>.

Each of first component <NUM> and second component <NUM> may be made using at least one of casting, forging, powder metallurgy, or additive manufacturing. In some examples, first component <NUM> and second component <NUM> are made using the same process, while in other examples, first component <NUM> and second component <NUM> are made using different processes.

Although <FIG> illustrates first component <NUM> and second component <NUM> as each defining a simple, substantially rectangular geometry, in other examples, first component part <NUM>, second component <NUM>, or both may define a more complex geometry, including simple or complex curves, overhangs, undercuts, internal cavities, or the like.

First component <NUM> defines at least one joint surface <NUM>. Similarly, second component <NUM> defines at least one joint surface <NUM>. In some examples, joint surfaces <NUM> and <NUM> may define complementary shapes. <FIG> illustrates joint surfaces <NUM> and <NUM> as substantially flat surfaces. In other examples, joint surfaces <NUM> and <NUM> may define other, more complex shapes, including, for example, simple or complex curves, overhangs, undercuts, apertures, annuluses, or the like.

First component <NUM> and second component <NUM> are positioned such that joint surfaces <NUM> and <NUM> are adjacent to each other and define a joint location <NUM>. Joint location <NUM> may include any kind of simple or complex joint, including, for example, at least one of a bridle joint, a butt joint, a miter join, a dado joint, a groove joint, a tongue and groove joint, a mortise and tenon joint, a birdsmouth joint, a halved joint, a biscuit joint, a lap joint, a double lap joint, a dovetail joint, or a splice joint. Consequently, joint surfaces <NUM> and <NUM> may have any corresponding geometries to define the surfaces of the joint location <NUM>. For example, for a mortise and tenon joint, first component <NUM> may define a mortise (a cavity) and second component <NUM> may define a tenon (a projection that inserts into the mortise). As another example, for a splice joint, first component <NUM> may define a half lap, a bevel lap, or the like, and second component <NUM> may define a complementary half lap bevel lap, or the like.

In some examples, although not shown in <FIG> assembly <NUM> may include a clamp, press, or other mechanism for exerting pressure between first joint surface <NUM> and second joint surface <NUM> during the brazing technique. The pressure between first joint surface <NUM> and second joint surface <NUM> may facilitate formation of the braze joint, e.g., by helping to at least one of maintain the gap of joint region <NUM>, to promote flow of PSP braze material <NUM>, and to evacuate any gases or porosity in PSP braze material <NUM>, which reduces porosity in the braze joint.

Disposed in joint or joint location <NUM> is a PSP braze material <NUM>. PSP braze material <NUM> is a wide gap braze material. For example, PSP braze material <NUM> may include a powder mixture that has been sintered to form a pre-sintered preform. Sintering may reduce porosity compared to the powder, which may reduce porosity in joint region <NUM> during and after formation of the braze joint.

PSP braze material <NUM> is a Ni-based wide gap braze alloy. PSP braze material <NUM> may include greater amounts of alloying elements that some other braze materials used in braze foils, which may contribute to improved mechanical properties, chemical properties, or both compared to some other braze materials used in braze foils. For example, PSP braze material <NUM> may possess sufficient mechanical strength and high temperature oxidation resistance to be used in a nozzle guide vane in a gas turbine engine.

In some examples, PSP braze material <NUM> may include both a braze alloy powder (a low-melt powder composition) and a superalloy powder (a high-melt powder composition). The low-melt alloy powder composition is an alloy, or a mixture of alloys, that substantially melts below the braze temperature (hence the name "low-melt" or "braze powder"). In contrast, the high-melt alloy powder composition is an alloy, or a mixture of alloys, that remains substantially unmelted at the braze temperature, because the composition has a melting temperature above the braze temperature (hence the name "high-melt" or "superalloy powder"). In some implementations, the braze alloy powder and the superalloy powder may have specific powder mesh sizes, and may be produced by induction melting the braze alloy or the superalloy powder, respectively, in vacuum or an argon atmosphere, followed by argon gas atomization. Each individual powder component used in PSP braze material <NUM> may be analyzed to confirm the particle size and chemical compositions.

In some examples, the low-melt powder composition includes an alloy or a mixture of alloys that melt at a temperature below about <NUM> (about <NUM>° F), with the alloy or mixture of alloys being selected so that the low-melt powder composition as a whole substantially melts at a temperature between about <NUM> (about <NUM>°F) and about <NUM> (about <NUM>°F). The high-melt alloy powder composition may include a single high-melt alloy or a mixture of alloys that melts at a temperature of greater than about <NUM> (about <NUM>° F).

In some examples, the low-melt powder composition may include one or more alloy powders and includes between about <NUM> wt. % and about <NUM> wt. % Ni, between about <NUM> wt. % and about <NUM> wt. % Cr, between about <NUM> wt. % and about <NUM> wt. % Ta, between about <NUM> wt. % and about <NUM> wt. % Co, between about <NUM> wt. % and about <NUM> wt. % Al, up to about <NUM> wt. % B, and up to about <NUM> wt. % Si, and has a compositional melting range of between about <NUM> (about <NUM>°F) and about <NUM> (about <NUM>°F). In some examples, the low-melt powder composition also includes up to about <NUM> wt. % each of at least one of Ti, W, Mo, Re, Nb, Hf, Pd, Pt, Ir, Ru, C, Si, P, Fe, Ce, La, Y, or Zr. In some examples the low-melt alloy powder comprises a mixture of two or more low-melt alloys. For example, a low-melt alloy powder may include (a) about <NUM>% of a first low-melt powder including about <NUM> wt. % Ni, about <NUM> wt. % Cr, about <NUM> wt. % Al, about <NUM> wt. % Co, and about <NUM> wt. % B, with a liquidus temperature of about <NUM> (about <NUM>° F); (b) about <NUM>% of a second low-melt powder including about <NUM> wt. % Ni, about <NUM> wt. % Cr, about <NUM> wt. % Ta, and about <NUM> wt. % B, with a liquidus temperature of about <NUM> (about <NUM>° F); and (c) about <NUM> wt. % of a third low-melt powder including about <NUM> wt. % Ni, about <NUM> wt. % Al, about <NUM> wt. % Co, about <NUM> wt. % W, about <NUM> wt. % Ta, about <NUM> wt. % Si, about <NUM> wt. % Re, about <NUM> wt. % Nb, and about <NUM> wt. % B, with a liquidus temperature of about <NUM> (about <NUM>° F).

In some examples, the high-melt powder composition may include an alloy or mixture of alloys with a chemistry that is the similar to or substantially the same (e.g., the same or nearly the same) as the alloy in first component <NUM>, second component <NUM>, or both. For example, in some implementations, to join a first component <NUM> and a second component <NUM> that include Ni-based superalloy components such as those made of MAR-M246 or <NUM>, or CMSX-<NUM> or -<NUM>, the high-melt powder composition may include between about <NUM> wt. % and about <NUM> wt. % Ni, between about <NUM> wt. % and about <NUM> wt. % Cr, between about <NUM> wt. % and about <NUM> wt. % Ta, between about <NUM> wt. % and about <NUM> wt. % Co, between about <NUM> wt. % and about <NUM> wt. % Al, between about <NUM> wt. % and about <NUM> wt. % W, between about <NUM> wt. % and about <NUM> wt. % Re, up to about <NUM> wt. % Mo, and up to about <NUM> wt. In some examples, the high-melt powder composition also may include up to about <NUM> wt. % each of at least one of Ti, Nb, C, B, Si, or Zr. In some examples, the high-melt powder composition includes between about <NUM> wt. % and about <NUM> wt. % Ni, about <NUM> wt. % Cr, about <NUM> wt. % Ta, about <NUM> wt. % Co, about <NUM> wt. % Al, about <NUM> wt. % Re, about <NUM> wt. % Hf, and about <NUM> wt.

The low-melt powder composition and the high-melt powder composition may be combined in a selected ratio. In some examples, PSP braze material <NUM> may include a powder mixture consisting of between about <NUM> wt. % and about <NUM> wt. % low-melt powder composition and a balance high-melt powder composition (a ratio of between about <NUM>:<NUM> and about <NUM>:<NUM> low-melt:high-melt powder). In some cases, braze alloy powder may be a mixture of more than one braze alloys which are all powder. In some examples, the ratio may be between about <NUM>:<NUM> and about <NUM>:<NUM> low-melt:high-melt powder, such as a ratio between about <NUM>:<NUM> and about <NUM>:<NUM> low-melt:high-melt powder, or a ratio between about <NUM>:<NUM> and about <NUM>:<NUM> low-melt: high-melt powder. For example, PSP braze material <NUM> may include between about <NUM> wt. % and about <NUM> wt. % low-melt alloy powder and between about <NUM> wt. % and about <NUM> wt. % high-melt powder, such as about <NUM> wt. % low-melt alloy powder and about <NUM> wt. % high-melt powder.

Hence, PSP braze material <NUM> includes between about <NUM> wt. % and about <NUM> wt. % Ni, between about <NUM> wt. % and about <NUM> wt. % Cr, between about <NUM> wt. % and about <NUM> wt. % Ta, between about <NUM> wt. % and about <NUM> wt. % Co, between about <NUM> wt. % and about <NUM> wt. % Al, between about <NUM> wt. % and about <NUM> wt. % W, between about <NUM> wt. % and about <NUM> wt. % Re, about <NUM> wt. % Mo, about <NUM> wt. % Hf, and, optionally, up to about <NUM>% each at least one of Ti, Nb, Pd, Pt, Ir, Ru, C, P, Mn, Fe, Ce, La, Y, or Zr. In some examples, PSP braze material <NUM> may include between about <NUM> wt. % and about <NUM> wt. % Ni, between about <NUM> wt. % and about <NUM> wt. % Cr, between about <NUM> wt. % and about <NUM> wt. % Ta, between about <NUM> wt. % and about <NUM> wt. % Co, between about <NUM> wt. % and about <NUM> wt. % Al, between about <NUM> wt. % and about <NUM> wt. % W, between about <NUM> wt. % and about <NUM> wt. % Re, between about <NUM> wt. % and about <NUM> wt. % Mo, between about <NUM> wt. % and about <NUM> wt. % Hf, between about <NUM> wt. % and about <NUM> wt. % Nb, between about <NUM> wt. % and about <NUM> wt. % Si, and between about <NUM> wt. % and about <NUM> wt.

In selecting the proportions of components used in PSP braze material <NUM>, higher weight percentages of high-melt powder may provide better mechanical properties in view of their reduced levels of boron, silicon, or both. Conversely, higher percentages of low-melt powders may provide improved braze flow. A proper balance between mechanical properties and braze flow should be selected.

In some examples, PSP braze material <NUM> that includes higher Al content may possess improved high-temperature oxidation resistance properties compared to PSP braze material <NUM> with lower Al content. Further, increasing Ta content in PSP braze material <NUM> may improve mechanical properties of the braze joint compared to lower Ta content. In particular, Ta may strengthen the gamma and gamma prime phases by increasing lattice mismatches.

PSP braze material <NUM> may be formed by mixing an alloy powder or multiple alloy powders in a selected composition, then sintering the powder while disposed in a mold to form a sintered preform with reduced porosity. The sintering temperature and the duration of the sintering may depend at least in part on the composition of the alloy powder or multiple alloy powders.

In some examples, the sintered powder may then be cut or machined into a predetermined shape. For example, the predetermined shape may correspond to a shape of joint region <NUM>. As described above, joint region <NUM> may include a relatively simple geometry as shown in <FIG>, or may include a more complex geometry, e.g., multiple planes or surfaces, simple or complex curves, overhangs, undercuts, internal cavities, or the like. Accordingly, the sintered powder may be cut or machined into a relatively simple shape, or a more complex, e.g., including curvature, angles, apertures, or the like to form PSP braze material <NUM>. Regardless of the complexity of the shape of PSP braze material <NUM> and depending upon the geometry of joint region <NUM>, PSP braze material <NUM> may include a substantially two-dimensional shape (e.g., a plane) or a three-dimensional shape (e.g., including curvature, planes at angles with respect to one another, and the like).

In some examples, PSP braze material <NUM> may define a thickness (e.g., in the direction between first joint surface <NUM> and second joint surface <NUM>) that is less than or equal to about <NUM> micrometers (about <NUM> inch). In some examples, PSP braze material <NUM> may define a thinner thickness, such as about <NUM> micrometers (about <NUM> inch). In other examples, PSP braze material <NUM> may define a greater thickness, such as up to about <NUM> micrometers (about <NUM> inch), or about <NUM> micrometers (about <NUM> inch).

By utilizing PSP braze material <NUM>, alloys with desirable mechanical and chemical (e.g., high temperature oxidation resistance) may be utilized in a brazing technique to join first component <NUM> and second component <NUM>. The resulting braze joint may possess sufficient mechanical strength and high temperature oxidation resistance to be utilized in a high temperature mechanical system, such as a nozzle guide vane in a gas turbine engine. Further, by utilizing a PSP, the braze joint may include reduced porosity compared to a joint formed using a braze powder, and positioning of the braze material may be easier and more precise than with a braze powder. In this way, PSP braze material <NUM> may facilitate using brazing to join components used in a high temperature mechanical system, which may allow formation of an article from multiple, smaller components, easing or reducing the cost of forming the article.

<FIG> is a flow diagram illustrating an example technique for joining a first component including a metal or alloy and a second component including a metal or alloy using a pre-sintered preform (PSP) braze material. The technique of <FIG> will be described with reference to assembly <NUM> of <FIG> for purposes of illustration only. It will be appreciated that the technique of <FIG> may be performed with a different assembly, or that assembly <NUM> may be used in a different brazing technique.

Although not shown in <FIG>, in some examples, prior to positioning first component <NUM> and second component <NUM> to define joint region <NUM> (<NUM>), first joint surface <NUM> and second joint surface <NUM> of first and second component <NUM> and <NUM>, respectively, may be inspected and cleaned. This cleaned joint surfaces <NUM> and <NUM> may produce a stronger braze joint than uncleaned joint surfaces.

The technique of <FIG> includes positioning first component <NUM> and second component <NUM> to define joint region <NUM> (<NUM>). For example, as shown in <FIG>, first component <NUM> and the second component <NUM> may be positioned so that joint surfaces <NUM> and <NUM> are near each other. As describe above, the geometry of joint region <NUM> may depend on the type of joint defined by joint surfaces <NUM> and <NUM> and may include, for example, a bridle joint, a butt joint, a scarf joint, a miter join, a dado joint, a groove joint, a tongue and groove joint, a mortise and tenon joint, a birdsmouth joint, a halved joint, a biscuit joint, a lap joint, a double lap joint, a dovetail joint, or a splice joint.

The technique of <FIG> also include disposing PSP braze material <NUM> in joint region <NUM> (<NUM>). As described above, PSP braze material <NUM> may define a predetermined shape that at least partially corresponds to the geometry of joint region <NUM>. As joint region <NUM> may include a relatively simple geometry or a more complex geometry, PSP braze material <NUM> may be cut or machined into a relatively simple shape, or a more complex shape, e.g., including curvature, angles, apertures, or the like. PSP braze material <NUM> is disposed in joint region <NUM> such that surface of PSP braze material <NUM> contacts joint surfaces <NUM> and <NUM>. In some examples, a clamp, press, or other mechanism may be used to compress PSP braze material <NUM> between joint surfaces <NUM> and <NUM> to cause intimate contact between joint surfaces <NUM> and <NUM> and surfaces of PSP braze material <NUM>.

The technique of <FIG> further includes heating PSP braze material <NUM> to melt at least part of PSP braze material (<NUM>). In some examples, PSP braze material <NUM> may be heated in a furnace or other closed retort, and first component <NUM> and second component <NUM> may be heated with PSP braze material <NUM>. In some examples, the furnace or closed retort may enclose a vacuum or substantially inert atmosphere (e.g., an atmosphere including constituents that substantially do not react with components <NUM> and <NUM> and PSP braze material <NUM> at the temperatures and pressures experienced by the interior of the furnace or closed retort). In some examples, PSP braze material <NUM> may be heated at a braze temperature of between about <NUM> (about <NUM>° F) and about <NUM> (about <NUM>° F), such as a braze temperatures of about <NUM> (about <NUM>° F). The time for which PSP braze material <NUM> is heated at the braze temperature may vary from about <NUM> minutes to about <NUM> minutes, for example between about <NUM> to <NUM> minutes.

Regardless of the heat treatment used for melting PSP braze material <NUM> (<NUM>), PSP braze material <NUM> is allowed to cool, for example to ambient temperature, to form a solid and join first component <NUM> and second component <NUM> (<NUM>). For example, PSP braze material <NUM> may be cooled in a vacuum or inert gas furnace to about <NUM> (about <NUM>° F) at a rate that is slow enough to avoid thermal distortion, followed by cooled under flowing inert gas to about <NUM> (about <NUM>° F) or less.

Following the brazing technique illustrated in <FIG>, the article including first component <NUM> and second component <NUM> joined by PSP braze material <NUM> may optionally be subjected to a diffusion heat treatment cycle to homogenize joint region <NUM>. For example, the diffusion heat treatment may be performed at temperatures between about <NUM> (about <NUM>°F) and about <NUM> (about <NUM>°F) below the braze temperature (e.g., below the highest braze temperature used in a stepped heat treatment), and for times of up to about <NUM> hours. For example, the post-brazing diffusion heat treatment cycle may include a stepped diffusion heat treatment cycle at a temperature of about <NUM> (about <NUM>°F for about <NUM> hour to about <NUM> hours. In some examples, during the diffusion heat treatment, the article including first component <NUM> and second component <NUM> joined by PSP braze material <NUM> is disposed in a vacuum or inert atmosphere.

In some examples, the stepped diffusion heat treatment cycle may include heating the article including PSP braze material <NUM>, first component <NUM>, and second component <NUM> at a rate of between about <NUM>/minute (about <NUM>°F/minute) and about <NUM>/minute (about <NUM>°F/minute) to a first temperature of between about <NUM> (about <NUM>°F) and about <NUM> (about <NUM>° F). In some examples, the article may be held at the first temperature for about <NUM> minutes to about <NUM> hours. The stepped heat treatment may also include heating the article to a second temperature of between about <NUM> (about <NUM>° F) and about <NUM> (about <NUM>° F) at a rate of between about <NUM>/minute (about <NUM>°F/minute) and about <NUM>/minute (about <NUM>°F/minute). The article may be held at the second temperature for between about <NUM> hour and about <NUM> hours. In some examples, the stepped heat treatment further includes heating the article to a third temperature of between about <NUM> (about <NUM>° F) and about <NUM> (about <NUM>° F) at a rate of between about <NUM>/minute (about <NUM>°F/minute) and about <NUM>/minute (about <NUM>°F/minute). The article may be held at the third temperature for between about <NUM> hour and about <NUM> hours. The stepped heat treatment also may include heating the article to a fourth temperature of between about <NUM> (about <NUM>° F) and about <NUM> (about <NUM>° F) at a rate of between about <NUM>/minute (about <NUM>°F/minute) and about <NUM>/minute (about <NUM>°F/minute). The article may be held at the fourth temperature for between about <NUM> hours and about <NUM> hours.

In some examples, the article may be heated at a rate of about <NUM>/minute (about <NUM>°F/minute) a first temperature of about <NUM> (about <NUM>° F) and held at about <NUM> for about <NUM> hour to about <NUM> hours. The article then may be heated to a second temperature of about <NUM> (about <NUM>° F) at a rate of about <NUM>/minute (about <NUM>°F/minute) and held at about <NUM> for about <NUM> hour to about <NUM> hours. The article then may be heated to a third temperature of about <NUM> (about <NUM>° F) at a rate of about <NUM>/minute (about <NUM>°F/minute) and held at about <NUM> for about <NUM> hour to about <NUM> hours. The article then may be heated to a fourth temperature of about <NUM> (about <NUM>° F) at rate of about <NUM>/minute (about <NUM>°F/minute) and held at about <NUM> for about <NUM> hour to about <NUM> hours.

Although <FIG> illustrates a simplified conceptual and schematic view of an example first component <NUM>, an example second component <NUM>, and an example PSP braze material <NUM>, in other example, at least one of first component <NUM>, second component <NUM>, and PSP braze material <NUM> may define a more complicated geometry. For example, <FIG> is a conceptual and schematic diagram illustrating an example first component <NUM> including a metal or alloy, an example second component <NUM> including a metal or alloy, and example PSP braze materials <NUM>, <NUM> used to form an article <NUM>. In the example illustrated in <FIG>, first component <NUM> includes a nozzle guide vane (NGV) for a gas turbine engine, second component <NUM> includes a NGV for a gas turbine engine, and article <NUM> includes a doublet NGV. First component <NUM> includes an outer platform 50a, an inner platform 54a, and an airfoil 52a that may be cast as a single, integral piece. Similarly, second component <NUM> includes an outer platform 50b, an inner platform 54b, and an airfoil 52b that may be cast as a single, integral piece. Each of first and second components <NUM> and <NUM> may be formed of a metal or alloy, such as a Ni- or Co-based superalloy. Further, first and second components <NUM> and <NUM> may be formed of the same metal or alloy, or first component <NUM> may be formed of a different alloy than second component <NUM>.

As shown in <FIG>, the joints between first component <NUM> and second component <NUM> are defined by outer platforms 50a and 50b and by inner platforms 54a and 54b. The joints possess a more complex geometry than that shown in <FIG>. First PSP braze material <NUM> and second PSP braze material <NUM> accordingly include a more complex geometry, shaped to substantially conform to the geometry of the respective joints in which first PSP braze material <NUM> and second PSP braze material <NUM> are positioned. Upon completion of the brazing technique, first PSP braze material <NUM> joins outer platforms 50a and 50b and second PSP braze material <NUM> joins inner platforms 54a and 54b. In this way, PSP braze materials <NUM> and <NUM> are used to join two simpler components, first and second components <NUM> and <NUM>, to form an article <NUM> with a more complex geometry. This may reduce manufacturing time and cost compared to forming article <NUM> from a single casting.

<FIG> is a conceptual and schematic diagram illustrating other example components including a metal or alloy and example PSP braze materials used to form a joined article. In the example illustrated in <FIG>, first component <NUM> includes an outer platform of a doublet NGV for a gas turbine engine, second component <NUM> includes an inner platform of the doublet NGV, third component <NUM> includes a first airfoil for the doublet NGV, and fourth component <NUM> includes a second airfoil for the doublet NGV. Each of first component <NUM>, second component <NUM>, third component <NUM>, and fourth component <NUM> may be formed as a respective single, integral piece. Each of first component <NUM>, second component <NUM>, third component <NUM>, and fourth component <NUM> may be formed of a metal or alloy, such as a Ni- or Co-based superalloy. Further, first component <NUM>, second component <NUM>, third component <NUM>, and fourth component <NUM> may be formed of the same metal or alloy, or at least one of first component <NUM>, second component <NUM>, third component <NUM>, and fourth component <NUM> may be formed of a different alloy than at least one other of first component <NUM>, second component <NUM>, third component <NUM>, and fourth component <NUM>.

As shown in <FIG>, the joints between first component <NUM> and third component <NUM>, between first component <NUM> and fourth component <NUM>, between second component <NUM> and third component <NUM>, and between second component <NUM> and fourth component <NUM> possess a more complex geometry than that shown in <FIG>. First PSP braze material 70a, second PSP braze material 70b, third PSP braze material 70c, and fourth PSP braze material 70d accordingly include more complex geometries, shaped to substantially conform to the geometry of the respective joints in which first PSP braze material 70a, second PSP braze material 70b, third PSP braze material 70c, and fourth PSP braze material 70d are positioned. Upon completion of the brazing technique, first PSP braze material 70a joins first component <NUM> and third component <NUM>, second PSP braze material 70b joins second component <NUM> and third component <NUM>, third PSP braze material 70c joins first component <NUM> and fourth component <NUM>, and fourth PSP braze material 70d joins second component <NUM> and fourth component <NUM>. In this way, PSP braze materials 70a-70d are used to a plurality of simpler components to form an article <NUM> with a more complex geometry. This may reduce manufacturing time and cost compared to forming article <NUM> from a single casting.

<FIG> is a photograph illustrating example tensile test specimens including two components joined using pre-sintered preform braze materials after room temperature tensile stress testing. Each of the test samples were made of two portions of CMSX-<NUM> base alloy joined by a PSP braze material. As described above, CMSX-<NUM> has a composition of about <NUM> wt. % Cr, about <NUM> wt. % Al, about <NUM> wt. % Ti, about <NUM> wt. % Co, about <NUM> wt. % W, about <NUM> wt. % Mo, about <NUM> wt. % Ta, and about <NUM> wt. % Hf, and a balance Ni. The PSP braze material in this Example included a composition of about <NUM> wt. % Cr, about <NUM> wt. % Al, about <NUM> wt. % Co, about <NUM> wt. % W, about <NUM> wt. % Mo, about <NUM> wt. % Ta, about <NUM> wt. % B, about <NUM> wt. % Si, about <NUM> wt. % Re, and about <NUM> wt. % Hf, about <NUM> wt. % Nb, and a balance Ni.

Each sample had an original geometry in the narrow region of about <NUM> (<NUM> inch) wide by about <NUM> (<NUM> inch) thick.

Tensile tests were performed on the samples shown in <FIG> at room temperature. Each sample was exposed to a strain of up to about <NUM>% at a rate of about <NUM>×<NUM>-<NUM>/s (<NUM> inch/inch/minute) per ASTM E-<NUM> using a tensile mechanical testing machine. As shown in <FIG>, the left-most two samples failed in the base metal rather than the braze joint. For the other three samples, although the braze joint failed, the tensile properties of the braze joints were between about <NUM> % and <NUM> % of the tensile properties of the CMSX-<NUM> base material, as shown in Table <NUM>.

<FIG> is a photograph illustrating example tensile test specimens including two components joined using pre-sintered preform braze materials after high temperature tensile stress testing. Each of the test samples were made of two portions of CMSX-<NUM> base alloy joined by a PSP braze material. As described above, CMSX-<NUM> has a composition of about <NUM> wt. % Cr, about <NUM> wt. % Al, about <NUM> wt. % Ti, about <NUM> wt. % Co, about <NUM> wt. % W, about <NUM> wt. % Mo, about <NUM> wt. % Ta, and about <NUM> wt. % Hf, and a balance Ni. The PSP braze material in this Example included a composition of about <NUM> wt. % Cr, about <NUM> wt. % Al, about <NUM> wt. % Co, about <NUM> wt. % W, about <NUM> wt. % Mo, about <NUM> wt. % Ta, about <NUM> wt. % B, about <NUM> wt. % Si, about <NUM> wt. % Re, and about <NUM> wt. % Hf, about <NUM> wt. % Nb, and a balance Ni.

Tensile tests were performed on the samples shown in <FIG> at an elevated temperature of about <NUM> (about <NUM>°F). Each sample was exposed to a strain of up to about <NUM>% at a rate of about <NUM>×<NUM>-<NUM>/s (<NUM> inch/inch/minute) per ASTM E-<NUM> using a tensile mechanical testing machine. As shown in <FIG>, each of the samples failed at the braze joint. Although the braze joint failed, the tensile properties of the braze joints were between about <NUM> % and <NUM> % of the tensile properties of the CMSX-<NUM> base material at the elevated temperature, as shown in Table <NUM>.

Claim 1:
A method comprising:
positioning a first component comprising a first metal or alloy and a second component comprising a second metal or alloy to each other to define a joint region between adjacent portions of the first component and the second component;
positioning a pre-sintered preform (PSP) braze material in the joint region, wherein the PSP braze material comprises a wide gap braze material;
heating the PSP braze material to form a molten braze alloy; and
cooling the molten braze alloy to join the first and second components;
characterized in that the wide gap braze material comprises one of:
between <NUM> wt. % and <NUM> wt. % Ni, between <NUM> wt. % and <NUM> wt. % Cr, between <NUM> wt. % and <NUM> wt. % Ta, between <NUM> wt. % and <NUM> wt. % Co, between <NUM> wt. % and <NUM> wt. % Al, between <NUM> wt. % and <NUM> wt. % W, between <NUM> wt. % and <NUM> wt. % Re, <NUM> wt. % Mo, <NUM> wt. % Hf, and, optionally, up to <NUM> wt. % each of at least one of Ti, Nb, Pd, Pt, Ir, Ru, C, B, Si, P, Mn, Fe, Ce, La, Y, or Zr; or
between <NUM> wt. % and <NUM> wt. % Ni, between <NUM> wt. % and <NUM> wt. % Cr, between <NUM> wt. % and <NUM> wt. % Ta, between <NUM> wt. % and <NUM> wt. % Co, between <NUM> wt. % and <NUM> wt. % Al, between <NUM> wt. % and <NUM> wt. % W, between <NUM> wt. % and <NUM> wt. % Re, between <NUM> wt. % and <NUM> wt. % Mo, between <NUM> wt. % and <NUM> wt. % Hf, between <NUM> wt. % and <NUM> wt. % Nb, between <NUM> wt. % and <NUM> wt. % Si, and between <NUM> wt. % and <NUM> wt. % B.