Antioxidant nickel (Ni)-based superalloys, powders, parts and methods

Abstract

The invention relates to a nickel-based alloy comprising (in wt%): 6.0% to 10.0% cobalt (Co), 6.0% to 10.0% iron (Fe), 12.0% to 16.0% chromium (Cr), 4.2% to 5.4% aluminum (Al), 4.0% to 7.0% tantalum (Ta), 0.05% to 1.0% hafnium (Hf), 0.005% to 0.1% silicon (Si), and a sum of 0.03% to 0.3% rare earth (e.g. Scandium (Sc), yttrium (Y), actinides and / or lanthanides), at least 0.01% carbon (C), at least 0.005% zirconium (Zr), and nickel (Ni).

Description

Technical Field

[0001] The present invention relates to nickel-based gamma prime strengthened superalloys, powders, components and methods of producing the components.

[0002] The present invention also relates to its use for liquid metal deposition (LMD) of components such as, but not limited to, blades, vanes, heat shields, seals, and combustor parts in turbines or gas turbines. The present invention also relates to its use in powder bed processes such as, but not limited to, laser powder bed fusion (LPBF) of components such as, but not limited to, blades, vanes, heat shields, seals, and combustor parts in turbines or gas turbines. The present invention also relates to its use for casting of components such as, but not limited to, blades, vanes, heat shields, seals, and combustor parts in turbines or gas turbines. The present invention also relates to its use for hot components that require resistance to metal dusting. Background Art

[0003] Blade alloys are essential for critical components in aviation and land-based gas turbines, but are also used in other applications.

[0004] The differences between blade alloys depend on the level of knowledge and production technology available when they were developed, and on the different relative emphasis placed on properties such as hot corrosion resistance, oxidation resistance, weldability, phase stability and creep strength.

[0005] AM processability is related to weldability because they are largely welding processes.

[0006] Blade alloys are used in single crystal (SX), directionally solidified, columnar (DS) or equiaxed (CC) microstructures. Each grain is a crystal composed primarily of a gamma-phase matrix, which is essentially a solid solution of nickel (Ni) with elements such as cobalt (Co), iron (Fe), chromium (Cr), molybdenum (Mo), tungsten (W) and / or rhenium (Re), and gamma-phase particles, which are essentially a solid solution of Ni3Al with elements such as Ti, Ta and Nb. Each grain is a two-phase crystal in which the gamma-matrix and gamma-' particles share the same crystallographic orientation, and the boundaries between the matrix and the particles are coherent. If present, the grain boundaries are typically modified by carbides and / or borides that provide cohesive strength. Zirconium (Zr) also contributes to grain boundary cohesion.

[0007] Creep strength is provided by elements such as molybdenum (Mo), tungsten (W), and / or rhenium (Re), which provide solid solution strengthening of the gamma matrix, and elements such as titanium (Ti), tantalum (Ta), and / or niobium (Nb), which provide solid solution strengthening of gamma particles. Aluminum (Al) provides creep strength because it increases the amount of gamma particles and because the presence of gamma particles concentrates the level of molybdenum (Mo), tungsten (W), and / or rhenium (Re) in the matrix. The coarse grain structure achieved by multicrystalline casting or directional solidification casting, or even more effectively, the absence of grain boundaries as in single crystal casting, enhances creep resistance.

[0008] AM processes (such as LMD or LPBF) tend to produce fine-grained structures. Depending on the component being designed, the reduction in creep strength can be compensated by the design possibilities offered by AM processes.

[0009] The blade alloy obtains its protection against oxidation and corrosion by forming a protective (ie continuous and adherent) Cr2O3 layer and / or a protective (ie continuous and adherent) Al2O3 layer in the oxide scale.

[0010] It is generally believed that at least 12.0 wt% chromium (Cr) is required for the formation of protective Cr2O3. If Cr2O3 layers can be formed, they typically remain protective for a long time at temperatures up to 1173 K in the flowing hot gas environment in the gas turbine heat path.

[0011] If continuous Al2O3 layers can form, they typically do so only above temperatures of the order of 1123 K. As the temperature decreases, the activity of aluminum (Al) decreases, and eventually no protective Al2O3 forms.

[0012] Corrosive agents present in gas turbines, such as alkali metal salts, are generally considered to be particularly active in the range of 973K to 1123K, where they can exist as molten deposits. Since this is the temperature range in which protective Cr2O3 can be formed when the chromium (Cr) content is at least 12.0 wt%, a general rule of thumb is that if the chromium (Cr) content is below 12.0 wt%, the hot corrosion resistance representative of alkali metal salt corrosion will be compromised. Molybdenum (Mo) in the alloy will be present in the spinel above the protective layer and can react with and exacerbate the corrosive deposits. Therefore, too much molybdenum (Mo) is detrimental to hot corrosion resistance.

[0013] It is known that the hot corrosion resistance of low chromium (Cr) aerospace alloys CMSX-4 and MD2SX is significantly lower than that of alloys IN792 and IN738LC, which have more than 12.0 wt% chromium (Cr) at 1123K.

[0014] D. Goldschmidt in "Single-Crystal Blades" in "Materials for Advanced Power Engineering" (Part 1, 1994, pp. 661-674) teaches that the hot corrosion resistance of the blade alloy SC16 containing 16.0 wt% chromium (Cr) and 3.0 wt% molybdenum (Mo) is significantly lower than the hot corrosion resistance of the blade alloy IN738LC containing 16.0 wt% chromium (Cr) and 1.8 wt% molybdenum (Mo).

[0015] Recent studies have shown that hot corrosion is also a problem at temperatures down to at least 773K.

[0016] It is known that the new IGT alloys STAL15SX and STAL125Cc1 with chromium (Cr) content greater than 12.0wt% have significantly better resistance to hot corrosion stress corrosion cracking than low chromium (Cr) aviation alloys CM247CC and CMSX-4.

[0017] If the amount of alloying elements is too high, undesirable phases (UP) such as Sigma and Laves phases will form in service. Therefore, if the formation of excessive UP is to be avoided, an increase in the level of alloying elements other than chromium (Cr) must be accompanied by a reduction in chromium (Cr), which means a conflict between corrosion resistance and other properties. One specific effect of UP precipitation is a reduction in creep strength. Another effect is embrittlement of the blade alloy. Another effect is that if chromium (Cr) is trapped in chromium (Cr)-rich UP, oxidation resistance and corrosion resistance will be reduced.

[0018] In the context of high-firing-temperature gas turbines, it is generally accepted that high oxidation resistance means the ability to form a protective Al2O3 layer, such as is required to withstand metal temperatures at or above 1273K. Furthermore, it is necessary to suppress the flaking of the oxide scale, which is always caused by sulfur contamination. Furthermore, a margin must be left to prevent the loss of the ability to reform the protective aluminum oxide, as each reformation means a loss of aluminum (Al). Furthermore, the use of alloying elements such as titanium (Ti) will contaminate the Al2O3 layer, as titanium (Ti) partially replaces aluminum (Al) in the layer, making it less protective. Furthermore, it is advantageous to be able to selectively oxidize quickly to form Al2O3, as this reduces the thickness of the oxide scale and makes it less susceptible to flaking.

[0019] The ability to form protective Al2O3, and the margin required to prevent aluminum (Al) loss due to oxide scale exfoliation, is a complex function of the Al content and the combination of other alloying elements, which act synergistically to enhance or reduce this ability. In CALPHAD terminology, this ability is correlated with predicted Al activity. In the context of blade alloys, CALPHAD refers to the use of thermodynamic software (such as Thermocalc) to predict entities such as the partitioning of alloying elements between γ and γ'; liquidus, solidus, and γ' solvus temperatures; γ' content; risk of UP precipitation; and Al activity. Increased Al activity also means faster selective oxidation to form protective Al2O3.

[0020] The following observations can be found in the literature regarding the addition of alloying elements to improve oxidation resistance:

[0021] CA Barrett: "Statistical Analysis of Elevated Temperature Gravimetric Cyclic Oxidation Data of 36 Ni- and Cobalt (Co)-Base Superalloys Based on an Oxidation Attack Parameter NASA TM 105934" teaches that the ability to form a protective Al2O3 layer is provided by aluminum (Al), enhanced by chromium (Cr) and tantalum (Ta), slightly reduced by molybdenum (Mo) and tungsten (W), and significantly reduced by titanium (Ti) and niobium (Nb). This is based on extensive correlation studies of commercial and experimental blade alloys. This means that if the levels of chromium (Cr) and tantalum (Ta) are increased, or the levels of titanium (Ti) and niobium (Nb) are decreased, less aluminum (Al) is required to form a protective Al2O3 layer.

[0022] C. Sarioglu et al.: "The Control of Sulfur Content in Nickel-Base Single Crystal Superalloys and its Effect on Cyclic Oxidation Resistance Proceedings 'Superalloys 1996'" teaches that the incorporation of elements such as sulfur (S) severely reduces scale adhesion, but that this effect can be neutralized by a combination of clean casting and the addition of small, quantitative levels of reactive elements (RE). Without the addition of RE, sulfur (S) must be well below 1 ppm to avoid a deleterious effect on scale adhesion.

[0023] BAPint et al.: “Effect of Cycle Frequency on High-Temperature Oxidation Behavior of Alumina- and Chromia-Forming Alloys Oxidation of Metals, 58(1 / 2), 73-101(2002)” emphasizes the importance of S and further teaches the favorable RE effect when combined with small amounts of hafnium (Hf) and rare earth yttrium (Y).

[0024] P.Caron et al.: "Improvement of the Cyclic Oxidation Behavior ofUncoated Nickel Based Single Crystal Superalloys Materials Proceedings

[0025] 'Materials for Advanced Power Engineering 1994'" teaches the beneficial RE impact when combining small levels of hafnium (Hf) and silicon (Si).

[0026] BAPint et al.: "The use of Two Reactive Elements to Optimize Oxidation Performance of Alumina-Forming Alloys Materials at High Temperature 20(3)375-386, 2003" teaches that significant RE impact can be obtained when using various RE formulations, one example being the excellent cyclic oxidation resistance seen in testing of Haynes-214 containing small levels of zirconium (Zr), silicon (Si) and yttrium (Y).

[0027] It is generally accepted that the risk of hot tearing during AM processes (such as LMD or LPBF) and subsequent strain-age cracking during solutionization increases with increasing nominal γ' content (taken as the equilibrium carbon (C) content at 1123K) and γ' solvus temperature. Our internal experience is that IN939, with a γ' content of approximately 35 mol% and a solvus of approximately 1353K, can be readily processed, while IN738LC, with a nominal γ' content of 44 mol% and a solvus of approximately 1433K, can be processed if more qualification work and stricter requirements are placed on the levels of grain boundary elements such as boron (B) and zirconium (Zr), as well as the permissible level of silicon (Si). Higher γ' contents tend to require even more effort, including more elaborate and expensive AM production processes and even more qualification work. Therefore, it is advantageous to maintain the γ' content at or above the level of IN738LC, preferably at the level of IN939.

[0028] Most blade alloys can be categorized as traditional industrial gas turbine (IGT) alloys, aerospace alloys, or newer IGT alloys.

[0029] These alloys have >12.0 wt% chromium (Cr) to form protective Cr2O3 (see the accompanying figure). Conventional IGT blade alloys are unable to form protective Al2O3, although SCA425, with 4.0 wt% aluminum (Al) supplemented with 16.0 wt% chromium (Cr), is a dividing line. In-house oxidation testing at 1273 K shows that SCA425 will form a continuous layer of Al2O3 over most, but unfortunately not all, of its surface. Based on Thermocalc using the TTNi8 database, its aluminum (Al) activity at 1273 K is 3.1e-8. Conventional IGT alloys are not suitable for our purposes because they cannot form protective Al2O3.

[0030] Aerospace alloys include CM247CC for CC and DS casting, and CMSX-4 and Rene N5 for SX casting (see table). Due to their low chromium (Cr) levels, they have poor hot corrosion resistance. Due to their high aluminum (Al) and tantalum levels, and despite their low chromium (Cr) levels, most of them can form protective Al2O3. Due to their poor corrosion resistance, aerospace alloys are unsuitable for our purposes. Furthermore, their high γ' content, typically in the 60 to 70 mol% range, makes them difficult to process using AM processes such as LMD or LPBF.

[0031] The new IGT alloy family includes the SX alloy STAL15SX, the CC alloys STAL125CC1 and STAL15CC, and the LMD alloy STAL18SiLaY (see table). These alloys have sufficient chromium (Cr) to form protective Cr2O3 at low and moderate temperatures (typically up to about 1173 K). In addition, due to moderate to high levels of (Al) supplemented by significant levels of chromium (Cr) and tantalum (Ta), they form protective Al2O3 at high temperatures (typically above about 1123 K).

[0032] It is therefore an object of the present invention to overcome these problems. Summary of the Invention

[0033] This problem is solved by the alloy, powder, component and method according to the independent claims.

[0034] Further advantages are listed in the dependent claims and can be combined with one another as desired to produce further advantages.

[0035] The present invention aims to provide a combination of good hot corrosion resistance, excellent oxidation resistance, good processability for AM processes (e.g., LMD and LPBF), high phase stability, and good creep resistance according to AM standards. Alternatively, the present invention aims to provide a combination of high hot corrosion resistance, excellent oxidation resistance, high AM processability, high phase stability, and moderate creep resistance according to AM standards. In the present invention, creep strength can be traded off to some extent for improved hot corrosion resistance.

[0036] These sets are useful for repairing oxidation damage in components (such as, but not limited to, blades, vanes, heat shields, seals, and combustor parts in turbines or gas turbines) using AM processes (such as, but not limited to, LMD and LPBF). Furthermore, they are useful for cladding components (such as, but not limited to, blades, vanes, heat shields, seals, and combustor parts in turbines or gas turbines) using AM processes (such as, but not limited to, LMD or LPBF) to prevent in-service oxidation damage. Furthermore, they are useful for manufacturing highly oxidation-resistant components (such as, but not limited to, blades, vanes, heat shields, seals, and combustor parts in turbines or gas turbines) using AM processes (such as, but not limited to, LMD or LPBF). Furthermore, they are useful for precision casting components (such as, but not limited to, blades, vanes, heat shields, seals, and combustor parts in turbines or gas turbines). Furthermore, they are useful when using corrosive fuels (one example being corrosive biofuels). Furthermore, they are useful for controlling corrosive agents (such as sea salt) in inlet air. Furthermore, they are also useful for alternative applications such as controlling hot flowing hydrocarbons resulting in corrosive and carbonizing environments with low oxygen partial pressure (O2).

[0037] As one possible application area, effective internal cooling of the edges and tips of hot-stage components in gas turbines is difficult to achieve. Consequently, a significant portion of the cooling air used in the gas turbine is consumed by dilution air, which mixes with the hot gas stream near the tips and edges to locally reduce its temperature and prevent excessive oxidation damage. Therefore, any improvement in the metal's temperature resistance translates into a reduction in dilution air usage, thereby increasing the gas turbine's thermal efficiency and, consequently, reducing CO2 emissions.

[0038] The classification of traditional IGT alloys includes polycrystalline IN939, IN738L Carbon (C) and IN792 (see table)

[0039] IN939 IN738LC IN792 S15CC S125CC1 E125 E15Mo E15W E14 CM247CC Ni B B B B B B B B B B Cr 22.0 16.0 12.5 15.0 12.5 12.5 15.0 15.0 14.0 8.0 Fe 8.0 8.0 8.0 6.0 Co 19.0 8.5 9.0 5.0 5.0 8.0 8.0 8.0 9.5 Mo 1.8 1.8 1.0 1.5 1.0 1.5 1.0 0.6 W 2.0 2.6 4.0 3.7 3.5 3.7 2.5 3.7 2.0 9.5 Al 1.9 3.5 3.4 5.1 5.5 5.1 4.5 4.5 6.5 5.6 Ti 3.7 3.5 4.0 0.7 Ta 1.4 1.8 4.0 8.0 8.0 6.5 5.0 5.0 3.2 3.2 Nb 0.9 0.9 Hf 0.5 0.1 0.5 0.1 0.1 0.1 1.5 1.4 C 0.15 0.07 0.07 0.07 0.07 0.05 0.05 0.05 0.05 0.07 Zr 0.1 0.03 0.02 .015 .015 0.01 0.01 0.01 0.01 0.01 B 0.01 .015 .015 .015 .015 0.01 0.01 0.01 0.01 0.01 Si 0.01 0.01 0.01 0.01 0.01 0.01 Others 0.05Y 0.05Y 0.05Y 0.05Y γ′ [mol%] 35 44 52 52 59 44 32 34 48 65 Al activity 4.3 4.4 8.4 7.6 8.0 7.6 n.a.

[0040] Table: Element additions are in [wt%]. STAL15CC is abbreviated as S15CC, Edge125 is abbreviated as E125, etc. Aluminum activity values ​​are relative values ​​at 1273K, and γ' is the equilibrium content at 1123K.

[0041] With 12.5 wt% chromium (Cr) and <2.0 wt% molybdenum (Mo), STAL125CC1 is considered a standard for good hot corrosion resistance.

[0042] With 15.0 wt% chromium (Cr) and <2.9 wt% molybdenum (Mo), STAL15SX is considered the standard for high hot corrosion resistance.

[0043] CM247CC, manufactured using a low-sulfur process with sulfur (S) <5 ppm, is considered the standard for high oxidation resistance due to its ability to form protective alumina and effectively inhibit oxide flaking caused by sulfur. It is a commonly used blade alloy when high oxidation resistance is required. Excellent oxidation resistance is defined by the alloy's ability to survive rigorous cyclic oxidation tests with minimal damage, in which CM247CC is essentially destroyed.

[0044] The criterion for high AM processability is considered to be a combination of high LMD and LPBF processability. High LMD processability is considered to be the ability to perform crack-free LMD on a range of high-strength blade alloy substrates using welds with widths and heights on the order of 0.5 mm to 1 mm without subsequent strain-age cracking. High LPBF processability is considered to be the ability to print dog-bone and cruciform geometries (two established crack induction tests) without cracking and without subsequent strain-age cracking.

[0045] High phase stability is considered to be the phase stability as calculated using ThermoCalc with TTNi8 as the thermodynamic database at the same level as the new industrial gas turbine (IGT) alloys STAL15SX and STAL125CC1, which have no precipitation of undesirable phases (UPs) (such as Laves or Sigma) in creep tests in the range of 923K to 1123K with rupture times exceeding 10kh, and also do not form UPs in service.

[0046] Moderate creep resistance is considered to be creep resistance at the fine-grained IN939 level, such as obtained by LPBF of IN939. Good creep resistance is considered to be creep resistance at the fine-grained IN738LC level, such as obtained by LPBF of IN738LC.

[0047] In this invention, a judicious combination of iron (Fe) and cobalt (Co) significantly improves oxidation resistance and AM processability compared to STAL15CC. The addition of Fe and Co alters the ratio of aluminum (Al), reducing the γ' content and improving AM processability. By forcing the aluminum (Al) into the γ' matrix, oxidation resistance improves.

[0048] The alloy contains between 6.0 wt% and 10.0 wt% cobalt (Co), between 6.0 wt% and 10.0 wt% iron (Fe), between 12.0 wt% and 16.0 wt% chromium (Cr), between 4.2 wt% and 5.4 wt% aluminum (Al), between 4.0 wt% and 8.0 wt% tantalum (Ta), at least 0.01 wt% carbon (C), at least 0.005 wt% zirconium (Zr), 0.05 wt% and 1.5 wt% tantalum (Ta), and 0.1 wt% and 0.2 wt% tantalum (T). % hafnium (Hf), between 0.005 wt % and 0.1 wt % silicon (Si), a total of between 0.01 wt % and 0.3 wt % (in particular between 0.02 wt % and 0.3 wt %) of rare earths (such as scandium (Sc), yttrium (Y), actinides and lanthanides), optionally at least 0.5 wt % of molybdenum (Mo) or at least 0.5 wt % of tungsten (W) or at least 0.3 wt % of rhenium (Re) or at least 0.0015 wt % of boron.

[0049] In particular, the alloy contains between 3.0 wt% and 6.0 wt% of molybdenum (Mo) + tungsten (W) and / or rhenium (Re), with a maximum of 2.0 wt% of molybdenum (Mo).

[0050] Further advantages are obtained by 0.02 wt% and 0.3 wt% of carbon (C) + zirconium (Zr) + boron (B).

[0051] The following alloying element functions are respectively valid for all alloys of the present invention:

[0052] At least 12.0 wt% chromium (Cr) is used to enable the formation of protective Cr2O3 and thus achieve good hot corrosion resistance. The chromium (Cr) content is limited to 16.0 wt% to avoid the risk of excessive UP precipitation. Chromium (Cr) also contributes to the activity of aluminum (Al).

[0053] Optionally, at least 0.5 wt% molybdenum (Mo) is used to provide strength to the gamma matrix, but is preferably limited to at most 2.0 wt% to avoid deleterious effects on hot corrosion resistance.

[0054] Optionally, at least 0.5 wt%, more preferably at least 2.0 wt% tungsten (W) is used to provide strength to the gamma matrix, but is preferably limited to at most 4.5 wt% to avoid the risk of excessive UP.

[0055] Preferably, up to 1.0 wt% rhenium (Re) is used. At higher levels, its deleterious effect on phase stability may be greater.

[0056] At least 4.2 wt% aluminum (Al) is used to achieve high aluminum activity. The upper limit is set at 5.4 wt% to avoid excessive γ' formation and the associated loss of AM processability.

[0057] At least 4.0 wt% of tantalum (Ta) is used to provide strength and contribute to aluminum activity. The upper limit is set at 8.0 wt% to avoid excessive UP formation.

[0058] Hafnium (Hf) is used quantitatively in small amounts of at least 0.05 wt% to provide a sulfur (S) gettering effect, but can be set to higher levels to improve anti-wrinkling properties, for example, in applied aluminide or platinum aluminide coatings. The upper limit is set at 1.5 wt% to avoid the risk of excessive UP formation.

[0059] Preferably, at least 0.01 wt% carbon (C) is contained to provide grain boundary strengthening. The upper limit is preferably set at 0.15 wt% as higher levels may result in too brittle behavior.

[0060] At least 0.0015 wt% of boron (B) is contained to provide grain boundary strengthening. The upper limit is preferably set at 0.03 wt% because higher levels may reduce AM processability too much.

[0061] At least 0.005 wt% zirconium (Zr) is contained to provide grain boundary strengthening and act as a scavenger for sulfur (S). The upper limit is preferably set at 0.1 wt%, as in IN939, because higher levels can reduce AM processability too much.

[0062] Contains at least 0.02 wt% in total of scandium (Sc), yttrium (Y), actinides and lanthanides for sulfur scavenging. The upper limit is set at 0.3 wt% as higher levels may result in excessive rare earth oxide inclusions, which may cause brittle behavior.

[0063] At least 0.005 wt% silicon (Si) is contained to provide a beneficial catalytic effect on the formation of protective Al2O3. The upper limit is set at 0.1 wt% because higher levels may cause grain boundary embrittlement. DETAILED DESCRIPTION

[0064] The blade alloy according to the invention is preferably processed using a clean production process. To ensure best results, the blade alloy should contain less than 5 ppm sulphur, preferably less than 1 ppm sulphur (S).

[0065] The following example illustrates the concept of the present invention: Referring to the table, STAL15CC is a blade alloy with high strength, high oxidation resistance, and high hot corrosion resistance. However, with a γ' content of 52 mol%, it does not meet the AM processability targets. Furthermore, the goal was very high oxidation resistance, not just high oxidation resistance.

[0066] In one embodiment of the present invention, referred to as Edge125, see the table, cobalt (Co) is increased and iron (Fe) is introduced relative to STAL15CC.

[0067] This changes the proportion of aluminum (Al), forcing more aluminum (Al) into the gamma matrix. The gamma' content is therefore reduced. Tantalum (Ta) is then further reduced to provide approximately the same degree of tantalum strengthening per mol% of gamma' as in STAL15CC, and this also slightly reduces the gamma' content. The chromium (Cr) content is then reduced to maintain the good phase stability of STAL15CC, despite having more aluminum (Al), iron (Fe), and cobalt (Co) in the gamma matrix. The result is a gamma' content of 44 mol%, as predicted by ThermoCalc using TTNi8 as a database. This is the same level as in IN738LC, indicating similar AM processability. The chromium content in Edge125 is the same as in IN792 and STAL125CC1, and the molybdenum (Mo) content is as low as 1.0wt%, which indicates good hot corrosion resistance. Edge125 contains 1.0wt% molybdenum, 3.7wt% tungsten, and 6.5wt% tantalum as strengthening elements. This is significantly higher than Edge14. Compared to STAL15CC, the RE formula in Edge125 is extended by adding a small amount of yttrium (Y).

[0068] In one embodiment, referred to as Edge15W, see the table, the aluminum (Al) content is reduced relative to Edge125, thereby further reducing the γ' content.

[0069] Tantalum (Ta) was then further reduced to provide approximately the same degree of tantalum strengthening per mol% of gamma-ion as in STAL15CC and Edge125. Chromium (Cr) could now be increased to 15.0 wt% while maintaining the phase stability seen in Edge125 and STAL15CC. The gamma-ion level was reduced to 34 mol%, as predicted by ThermoCalc using TTNi8 as the database. This is similar to IN939. Due to the higher chromium (Cr) content, hot corrosion resistance is higher than Edge125. Edge15W contains 1.0 wt% molybdenum, 3.7 wt% tungsten, and 5.0 wt% tantalum (Ta). This is a higher level of strengthening elements than Edge14, especially in the gamma matrix.

[0070] Other embodiments may be developed by those skilled in the art, for example to better match a particular substrate and / or coating and to further enhance sulfur (S) gettering.

[0071] In Edge15Mo, see table, tungsten (W) is partially replaced by molybdenum (Mo) relative to Edge15W. Similarly, rhenium (Re) can be introduced at the expense of molybdenum (Mo) and / or tungsten (W) to obtain a better match with the rhenium-containing blade alloy.

[0072] The addition of yttrium (Y) can be replaced by a combination of yttrium (Y) and lanthanum (La) to further improve the RE formulation. Another possibility is the use of mixed metals. This is a mixture of rare earth elements, typically dominated by a combination of lanthanum (La), yttrium (Y), and cerium (Ce), and the use of mixed metals can be beneficial from a cost and performance perspective.

[0073] The predicted aluminum activities of Edge125, Edge15W, and Edge15Mo at 1273 K are 8.4e-8, 8.0e-8, and 7.6e-8, respectively. These are almost twice those of, for example, STAL15CC and STAL125CC1, see table, strongly suggesting extremely high oxidation resistance.

[0074] Edge15Mo has been successfully coated by LMD onto CM247CC (DS and CC castings), STAL125CC1, and IN792, with no cracking at the interface or within the coated Edge15Mo. Furthermore, no cracking was observed during the subsequent dissolution process, which was performed at the dissolution temperature of the substrate. This was achieved within a wide process window for welds measuring approximately 0.5 mm x 0.5 mm. Based on internal experience, this implies LMD processability at least at the level of IN939. Furthermore, crack-inducing geometries have been printed by LPBF using Edge15Mo, and no cracking was observed during the printing process or during the subsequent dissolution process at 1523 K. Despite lengthy process parameter optimization efforts, even these geometries have not been seen to be completely crack-free for LPBF of IN939.

[0075] A sample consisting of Edge15Mo coated on CM247CC via LMD was evaluated in cyclic oxidation tests. Due to the difficulty in finding test conditions that would damage the Edge15Mo, the test parameters became increasingly stringent, ultimately using a cyclic oxidation test of 1000 cycles, each held at 1523K for one hour. Higher temperatures could not be used because they would cause incipient melting of the substrate, which dissolves at approximately that temperature. In this test, the Edge15Mo material remained largely intact, while areas of the CM247CC substrate not protected by the Edge15Mo layer or in contact with the ceramic sample holder lost several millimeters. It should be noted that the slightly uneven surface on the Edge15Mo was not caused by oxidation but rather by the fact that it had been polished only after LMD coating prior to testing. CM247CC was used to illustrate the edge alloy concept because it is one of the most widely used polycrystalline alloys when high oxidation resistance is required.

[0076] It should be noted that Edge14 has also been coated on CM247CC via LMD, and such samples have been evaluated under the same very stringent test conditions as the CM247CC / Edge15Mo samples, with virtually identical results. In the case of CM247CC / Edge14, this can be considered normal, given the high aluminum content of 6.5 wt% supplemented by 14.0 wt% chromium. Edge15Mo, however, has a moderate aluminum (Al) content of 4.5 wt%, but due to the combination of 8.0 wt% cobalt (Co) and 8.0 wt% iron (Fe), its aluminum (Al) activity is remarkably similar to that of Edge14, demonstrating that Al activity is indeed a reliable indicator of oxidation resistance. Similar Al activity gives similar test results (when the active element formulation is also identical and the powders are obtained from the same supplier with similar quality in terms of contaminants).

[0077] It should also be mentioned that the aluminum (Al) activity of CM247CC is omitted from the table due to the fact that the database TTNi8 is known to perform poorly for CM247CC.

[0078] It should also be noted that the oxidation lifetime of applied Al2O3 forming a coating (e.g., an aluminide) benefits from using the edge alloy as the underlying substrate. This is because the primary mode of degradation of such coatings is aluminum loss from the coating by diffusion into the substrate. Therefore, if the aluminum activity of the substrate is increased, the loss of aluminum (Al) via diffusion is delayed. It should also be noted that aluminides and platinum aluminides can flake due to wrinkling, but this can be mitigated by including hafnium in the substrate, as the hafnium will diffuse into the coating and reduce wrinkling.

[0079] In addition to using this edge alloy to locally enhance the oxidation resistance and coating compatibility of parts cast or additively manufactured in other blade alloys, the edge alloy can also be used for additive manufacturing or casting of entire parts, provided these parts are subject to at most moderate creep loads. This includes, but is not limited to, seals, heat shields, blades with moderate creep loads, and combustor parts in gas turbines.

[0080] In one embodiment, referred to as Edge15, tungsten (W) and aluminum (Al) are reduced relative to Edge125, thereby further reducing the γ' content. Tantalum (Ta) is then further reduced to provide approximately the same degree of tantalum strengthening per mol% γ'. Chromium (Cr) can be increased to 15.0 wt% while maintaining the phase stability of STAL15CC. In Edge15W, the γ' level is reduced to approximately the same level as IN939, which is easily processed by LMD and LPBF. The overall strengthening level of Edge15W is similar to that of IN939, even though the strengthening ratio between γ and γ' is different. The γ matrix in Edge15W is strengthened by 1 wt% molybdenum (Mo) + 3.7 wt% tungsten (W), while IN939 is strengthened by only 2 wt% tungsten (W). The γ' particles in Edge15W are strengthened by 5.0wt% tantalum (Ta). However, the strengthening level per mol% γ' is still the same as that in STAL15CC and higher than that in ReneN5, while IN939 is strengthened by 3.7wt% titanium (Ti) + 1.4wt% tantalum (Ta) + 0.9wt% niobium (Nb). Therefore, from the perspective of strength and AM processability, Edge15W is comparable to IN939.

[0081] The aluminum (Al) activity in Edge15W and Edge15 molybdenum (Mo) is reduced relative to that of Edge125, but they are still significantly higher than that of STAL15C carbon (C), see the accompanying figure.

[0082] Unexpectedly, iron (Fe) and molybdenum (Mo) can significantly increase aluminum (Al) activity, as suggested by CALPHAD. However, oxidation resistance and Al activity are correlated with the Al content in the gamma matrix, and even in blade alloys capable of forming protective Al2O3, this is relatively low because most of the Al typically partitions into the gamma' particles. Because cobalt (Co) and iron (Fe) force more Al into the gamma matrix, the relative increase in Al content in the gamma matrix is ​​significant.

[0083] Edge15Mo was coated by LMD onto the aerospace alloy CM247DS, a DS-cast CM247CC composition, to facilitate the production of samples for oxidation testing. Due to the difficulty in finding test conditions that would damage the Edge15Mo material, testing parameters were increasingly stringent until a cyclic oxidation test of 1000 cycles at 1523K, with a hold time of one hour per cycle, was conducted. Higher temperatures could not be used because they would cause incipient melting of the substrate, which dissolves at approximately that temperature. In this test, the Edge15Mo material remained largely intact, while areas of the CM247CC substrate not protected by the Edge15Mo layer or in contact with the ceramic sample holder lost several millimeters.

[0084] Edge 15MO has also been used to print crack-inducing geometries in dogbone and cruciform specimens. Consistent crack-free printing was demonstrated, with no strain-age cracking during subsequent dissolution. This is not always observed even when printing IN939, and is rarely seen when printing alloys with higher γ' contents.

[0085] According to one embodiment of the present invention, the alloy may include 6.0 wt% to 10.0 wt% of cobalt (Co), 6.0 wt% to 10.0 wt% of iron (Fe), 12.0 wt% to 16.0 wt% of chromium (Cr), 3.0 wt% to 6.0 wt% of molybdenum (Mo) + tungsten (W) + (and / or) rhenium (Re), up to 2.0 wt% of molybdenum (Mo), 4.2 wt% to 5.4 wt% of Al, 4.0 wt% to 7.0 wt% of tantalum (Ta), 0.05 wt% to 0.15wt% of carbon (C) + zirconium (Zr) + boron (B), at least 0.03wt% of carbon (C), at least 0.01wt% of zirconium (Zr), 0.05wt% to 1.0wt% of hafnium (Hf), 0.005wt% to 0.1wt% of silicon (Si), a total of 0.03wt% to 0.3wt% of rare earths (such as scandium (Sc), yttrium (Y), actinides and lanthanides), and nickel (Ni), in particular, the remaining components are nickel (Ni) and unavoidable impurities.

[0086] In addition, the alloy may include between 7.0 wt% and 9.0 wt% cobalt (Co), between 7.0 wt% and 9.0 wt% iron (Fe), between 12.0 wt% and 13.5 wt% chromium (Cr), between 0.7 wt% and 1.3 wt% molybdenum (Mo), between 3.4 wt% and 4.0 wt% tungsten (W), between 4.9 wt% and 5.3 wt% aluminum, between 6.0 wt% and 8.0 wt% tantalum (Ta), 0.04 wt% to 0.08wt% of carbon (C), between 0.005wt% and 0.015wt% of zirconium (Zr), between 0.005wt% and 0.015wt% of boron (B), between 0.05wt% and 0.2wt% of hafnium (Hf), between 0.005wt% and 0.05wt% of silicon (Si), between 0.03wt% and 0.2wt% of yttrium (Y), and nickel (Ni), in particular, the remaining components are nickel (Ni) and inevitable impurities.

[0087] In a preferred embodiment referred to as Edge125, the alloy may include 8.0 wt% cobalt (Co), 8.0 wt% iron (Fe), 12.5 wt% chromium (Cr), 1.0 wt% molybdenum (Mo), 3.7 wt% tungsten (W), 5.1 wt% Al, 6.5 wt% tantalum (Ta), 0.05 wt% carbon (C), 0.01 wt% zirconium (Zr), 0.1 wt% hafnium (Hf), 0.01 wt% silicon (Si) and 0.05 wt% yttrium (Y), and nickel (Ni), in particular, the remaining components are nickel (Ni) and unavoidable impurities.

[0088] Alternatively, the alloy may include between 7.0 wt% and 9.0 wt% cobalt (Co), between 7.0 wt% and 9.0 wt% iron (Fe), between 13.5 wt% and 16.0 wt% chromium (Cr), between 0.7 wt% and 1.3 wt% molybdenum (Mo), between 3.4 wt% and 4.0 wt% tungsten (W), between 4.2 wt% and 4.8 wt% aluminum (Al), between 4.0 wt% and 6.0 wt% tantalum (Ta), 0.0 3wt% to 0.08wt% of carbon (C), 0.005wt% to 0.015wt% of zirconium (Zr), 0.005wt% to 0.015wt% of boron (B), 0.05wt% to 0.2wt% of hafnium (Hf), 0.005wt% to 0.05wt% of silicon (Si), 0.03wt% to 0.2wt% of yttrium (Y), and nickel (Ni), in particular, the remaining components are nickel (Ni) and unavoidable impurities.

[0089] In a preferred embodiment referred to as Edge15W, the alloy may include 8.0wt% cobalt (Co), 8.0wt% iron (Fe), 15.0wt% chromium (Cr), 1.0wt% molybdenum (Mo), 3.7wt% tungsten (W), 4.5wt% aluminum (Al), 5.0wt% tantalum (Ta), 0.05wt% carbon (C), 0.01wt% zirconium (Zr), 0.1wt% hafnium (Hf), 0.01wt% silicon (Si) and 0.05wt% yttrium (Y), and nickel (Ni), in particular, the remaining components are nickel (Ni) and unavoidable impurities.

[0090] Alternatively, the alloy may include between 7.0 wt% and 9.0 wt% cobalt (Co), between 7.0 wt% and 9.0 wt% iron (Fe), between 13.5 wt% and 16.0 wt% chromium (Cr), between 1.2 wt% and 1.8 wt% molybdenum (Mo), between 2.2 wt% and 2.8 wt% tungsten (W), between 4.2 wt% and 4.8 wt% aluminum (Al), between 4.0 wt% and 6.0 wt% tantalum (Ta), 0.04 wt% to 0.08wt% of carbon (C), 0.005wt% to 0.015wt% of zirconium (Zr), 0.005wt% to 0.015wt% of boron (B), 0.05wt% to 0.2wt% of hafnium (Hf), 0.005wt% to 0.05wt% of silicon (Si), 0.03wt% to 0.2wt% of yttrium (Y), and nickel (Ni), in particular, the remaining components are nickel (Ni) and inevitable impurities.

[0091] In a preferred embodiment referred to as Edge15W, the alloy may include 8.0wt% cobalt (Co), 8.0wt% iron (Fe), 15.0wt% chromium (Cr), 1.5wt% molybdenum (Mo), 2.5wt% tungsten (W), 4.5wt% Al, 5.0wt% tantalum (Ta), 0.05wt% carbon (C), 0.01wt% zirconium (Zr), 0.1wt% hafnium (Hf), 0.01wt% silicon (Si) and 0.05wt% yttrium (Y), and nickel (Ni), in particular, the remaining components are nickel (Ni) and unavoidable impurities.

[0092] The blade alloy according to the invention is preferably processed by a clean production process.To ensure best results, the blade alloy should contain less than 5 ppm sulphur (S), preferably less than 1 ppm sulphur (S).

[0093] Alternatively, when the alloy is used as a base alloy, other embodiments can be designed to optimize compatibility with specific coatings. Alternatively, when the alloy is used as a filler alloy for cladding and weld repairs, other embodiments can be designed to optimize compatibility with specific base alloys and coatings. In this case, the alloy of the present invention is added to a substrate with a different composition.

Claims

1. A nickel-based alloy comprising (in wt%): 6.0% to 10.0% cobalt (Co), 6.0% to 10.0% iron (Fe), 12.0% to 16.0% chromium (Cr), 4.2% to 5.4% aluminum (Al), 4.0% to 8.0% tantalum (Ta), in particular 4.0% to 7.0% Ta, 0.05% to 1.5% hafnium (Hf), 0.005% to 0.1% silicon (Si), 0.01% to 0.3% of rare earths, in particular 0.02% to 0.3% of rare earths, such as scandium (Sc), yttrium (Y), actinides and / or lanthanides, in, In particular, at least two rare earth elements are added. at least 0.01% carbon (C), and in particular at most 0.15% by weight carbon (C), at least 0.005% zirconium (Zr), and in particular at most 0.1 wt% zirconium (Zr), Nickel (Ni), in particular, the remainder is nickel (Ni) and inevitable impurities, Optionally, At least 0.5% molybdenum (Mo) and / or At least 0.5% tungsten (W) and / or At least 0.3% rhenium (Re) and / or At least 0.0015% boron (B), and in particular at most 0.03 wt% boron (B).

2. The alloy according to claim 1, comprising (in wt%): 3.0% to 6.0% of molybdenum (Mo) and / or tungsten (W) and / or rhenium (Re), In particular, up to 2.0% molybdenum (Mo) and / or in particular at least 2.0% tungsten (W).

3. The alloy according to claim 1 or 2, comprising (in wt%): 0.02% to 0.3% of carbon (C) and / or zirconium (Zr) and / or boron (B).

4. The alloy according to any one of claims 1, 2 or 3, comprising (in wt%): 7.0% to 9.0% cobalt (Co), 7.0% to 9.0% iron (Fe), 12.0% to 13.5% chromium (Cr), 0.7% to 1.3% molybdenum (Mo), 3.4% to 4.0% tungsten (W), 4.9% to 5.3% aluminum (Al), 6.0% to 8.0% tantalum (Ta), 0.04% to 0.08% carbon (C), 0.005% to 0.015% zirconium (Zr), 0.005% to 0.015% boron (B), 0.05% to 0.2% hafnium (Hf), 0.005% to 0.05% silicon (Si), 0.03% to 0.2% yttrium (Y).

5. The alloy of claim 4, comprising (in wt%): 8.0% cobalt (Co), 8.0% iron (Fe), 12.5% ​​chromium (Cr), 1.0% molybdenum (Mo), 3.7% tungsten (W), 5.1% aluminum (Al), 6.5% tantalum (Ta), 0.05% carbon (C), 0.01wt% zirconium (Zr), 0.1wt% hafnium (Hf), 0.01wt% silicon (Si), 0.05 wt% of yttrium (Y).

6. The alloy according to any one of claims 1, 2 and 3, comprising (in wt%): 7.0% to 9.0% cobalt (Co), 7.0% to 9.0% iron (Fe), 13.5% to 16.0% chromium (Cr), 0.7% to 1.3% molybdenum (Mo), 3.4% to 4.0% tungsten (W), 4.2% to 4.8% aluminum (Al), 4.0% to 6.0% tantalum (Ta), 0.03% to 0.08% carbon (C), 0.005% to 0.015% zirconium (Zr), 0.005% to 0.015% boron (B), 0.05% to 0.2% hafnium (Hf), 0.005% to 0.05% silicon (Si), 0.03% to 0.2% yttrium (Y).

7. The alloy of claim 6, comprising (in wt%): 8.0% cobalt (Co), 8.0% iron (Fe), 15.0% chromium (Cr), 1.0% molybdenum (Mo), 3.7% tungsten (W), 4.5% aluminum (Al), 5.0% tantalum (Ta), 0.05% carbon (C), 0.01% zirconium (Zr), 0.1% hafnium (Hf), 0.01% silicon (Si), 0.05% yttrium (Y).

8. The alloy of claim 6, comprising (in wt %): 8.0% cobalt (Co), 8.0% iron (Fe), 15.0% chromium (Cr), 1.5% molybdenum (Mo), 2.5% tungsten (W), 4.5% aluminum (Al), 5.0% tantalum (Ta), 0.05% carbon (C), 0.01% zirconium (Zr), 0.1% hafnium (Hf), 0.01% silicon (Si), 0.05% yttrium (Y).

9. The alloy according to any one of claims 1, 2 and 3, comprising (in wt%): 7.0% to 9.0% cobalt (Co), 7.0% to 9.0% iron (Fe), 13.5% to 16.0% chromium (Cr), 1.2% to 1.8% molybdenum (Mo), 2.2% to 2.8% tungsten (W), 4.2% to 4.8% aluminum (Al), 4.0% to 6.0% tantalum (Ta), 0.04% to 0.08% carbon (C), 0.005% to 0.015% zirconium (Zr), 0.005% to 0.015% boron (B), 0.05% to 0.2% hafnium (Hf), 0.005% to 0.05% silicon (Si), 0.03% to 0.2% yttrium (Y).

10. The alloy of claim 9, comprising (in wt%): 8.0% cobalt (Co), 8.0% iron (Fe), 15.0% chromium (Cr), 1.5% molybdenum (Mo), 2.5% tungsten (W), 4.5% aluminum (Al), 5.0% tantalum (Ta), 0.05% carbon (C), 0.01% zirconium (Zr), 0.1% hafnium (Hf), 0.01% silicon (Si), 0.05% yttrium (Y).

11. The alloy according to any one of claims 1, 2 and 3, comprising (in wt%): 7.0% to 9.0% cobalt (Co), 7.0% to 9.0% iron (Fe), 13.5% to 16.0% chromium (Cr), 0.7% to 1.7% molybdenum (Mo), 2.0% to 4.0% tungsten (W), 4.2% to 4.8% aluminum (Al), 4.0% to 6.0% tantalum (Ta), 0.03% to 0.08% carbon (C), 0.005% to 0.015% zirconium (Zr), 0.005% to 0.015% boron (B), 0.05% to 0.2% hafnium (Hf), 0.005% to 0.05% silicon (Si), 0.01% to 0.15% yttrium (Y), 0.01% to 0.15% lanthanum (La).

12. The alloy of claim 11, comprising (in wt%): 8.0% cobalt (Co), 8.0% iron (Fe), 15.0% chromium (Cr), 1.5% molybdenum (Mo), 2.5% tungsten (W), 4.5% aluminum (Al), 5.0% tantalum (Ta), 0.05% carbon (C), 0.01% zirconium (Zr), 0.1% hafnium (Hf), 0.01% silicon (Si), 0.025% yttrium (Y), 0.025% lanthanum (La).

13. The alloy according to any one of claims 1, 2, and 3, comprising (in wt%): 7.0% to 9.0% cobalt (Co), 7.0% to 9.0% iron (Fe), 13.5% to 16.0% chromium (Cr), 0.7% to 1.7% molybdenum (Mo), 2.0% to 4.0% tungsten (W), 4.2% to 4.8% aluminum (Al), 4.0% to 6.0% tantalum (Ta), 0.03% to 0.08% carbon (C), 0.005% to 0.015% zirconium (Zr), 0.005% to 0.015% boron (B), 0.05% to 0.2% hafnium (Hf), 0.005% to 0.05% silicon (Si), Rare earths, such as scandium (Sc), yttrium (Y), actinides and / or lanthanides, in a total amount of 0.02% to 0.2%.

14. A powder comprising particles made of an alloy according to any one of the preceding claims, Optionally, the powder comprises a binder for binder jet printing or abrasive particles for seals.

15. A component made from an alloy according to any one of the preceding claims 1 to 13.

16. A component having material added thereto by welding or printing using the alloy according to any one of claims 1 to 13 or the powder according to claim 13.

17. The component of claim 15 being additively manufactured.

18. The component according to claim 15, cast using the alloy according to any one of the preceding claims 1 to 13.

19. A method for producing a component by casting using an alloy according to any one of the preceding claims 1 to 13.

20. A method of producing a component by additive manufacturing using an alloy according to any one of the preceding claims 1 to 13.

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