EP4638815A1

EP4638815A1 - Oxidation resistant nickel based alloy and methods

Info

Publication number: EP4638815A1
Application number: EP24700885.7A
Authority: EP
Inventors: Magnus Hasselqvist
Original assignee: Siemens Energy Global GmbH and Co KG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2023-03-01
Filing date: 2024-01-11
Publication date: 2025-10-29
Also published as: GB2627777A; KR20250153295A; WO2024179728A1; CN120826482A; GB202302999D0; JP2026509212A

Abstract

The invention relates to a nickel base superalloy, comprising (in wt%): 2.0% to 10.0% Cobalt (Co), 3.0% to 10.0% Iron (Fe), 14.0% to 18.0% Chromium (Cr), 4.5% to 5.3% Aluminum (Al), 3.0% to 7.0% Tantalum (Ta), 0.01% to 0.05% Carbon (C), 0.01% to 0.05% Zirconium (Zr), 0.05% to 1.0% Hafnium (Hf), 0.3% to 0.7% Silicon (Si), 0.01% to 0.3% of the sum of rare earths such as Scandium (Sc), Yttrium (Y), the Actinides and/or the Lanthanides, Nickel (Ni), optionally: up to 3.0% Tungsten (W), and/or up to 2.0% Molybdenum (Mo), and/or up to 2.0% Rhenium (Re), and/or at most 0.05% Boron (B).

Description

Oxidation resistant Nickel based alloy and methods

The present invention relates to a nickel-base gamma prime strengthened superalloy. It further relates to its use for fabrication of hot components such as, but not restricted to, vanes, blades, heat shields, sealings and combustor parts in gas turbines . It further relates to its use as filler alloy for cladding and repair of components such as, but not restricted to, blades, vanes, heat shields and combustor parts in gas turbines. It further relates to its use in monocrystalline form. It further relates to its use for cladding of a monocrystalline substrate such that its monocrystalline structure is retained into and within the added or cladded volume .

Blade alloys are essential for critical components in aero and land-based gas turbines, but are used also in other applications. The differences between blade alloys depend on the level of knowledge and production technology available at the time they were developed, and, on different relative emphasis on properties such as hot corrosion resistance, oxidation resistance, weldability, phase stability and creep strength .

Blade alloys are used in monocrystalline (SX) , directionally solidified (columnar, DS) or equiaxed (CC) form. Each grain is a crystal mainly consisting of a matrix of the gamma phase, which is essentially Nickel (Ni) with elements like Cobalt (Co) , Iron (Fe) , Chromium (Cr) , Molybdenum (Mo) , Tungsten (W) and Rhenium (Re) in solid solution. Particles of the gamma prime phase, which is essentially Nia l with elements like Titanium, Tantalum (Ta) and Niobium (Nb) in solid solution. Each grain is a two-phase crystal in which the gamma matrix and the gamma prime particles share the same crystal orientation and the boundaries between the matrix and the particles are coherent. Grain boundaries, if present, are usually decorated by carbides and/or borides which provide cohesive strength . Zirconium ( Zr ) also contributes to grain boundary cohesion .

Creep strength is provided by elements like Molybdenum (Mo ) , Tungsten (W) and Rhenium ( Re ) , which provide solution strengthening of the gamma matrix , and Titanium (Ti ) , Tantalum ( Ta ) and Niobium (Nb ) which provide solution strengthening of the gamma prime particles . Aluminum (Al ) provides creep strength as it increases the amount of gamma prime particles , and, as the presence of gamma prime particles concentrates the levels of Molybdenum (Mo ) , Tungsten (W) and Rhenium ( Re ) in the matrix .

Efficient internal cooling of edges and tips on hot stage gas turbine parts is difficult to achieve , hence a significant amount of the cooling air used in a gas turbine is spent on dilution air which is mixed with the hot gas stream in the vicinity of tips and edges to locally reduce the temperature of said hot gas stream in order to avoid too much oxidation damage . Any improvement in metal temperature tolerance can therefore be translated into reduced dilution air usage resulting in improved gas turbine thermal efficiency and consequently reduced C0₂ emissions .

IN738LC is taken as the norm for high hot corrosion resistance . It is a commonly chosen blade alloy in gas turbines when a high hot corrosion resistance is required .

CM247CC, as fabricated by a low sulfur process with < 5ppm Sulfur ( S ) , is taken as the norm for high oxidation resistance thanks to its ability to form protective alumina, and efficiently suppress the oxide spallation caused by sulfur . It is a commonly chosen blade alloy when a high oxidation resistance is needed .

Edgel 4 , as fabricated with a low sulfur process , is taken as the norm for excellent oxidation resistance thanks to its ability to form protective alumina, and to suppress extremely efficiently the oxide scale spallation using an elaborate reactive element (Rhenium (Re) ) recipe based on Hafnium (Hf ) , Silicon (Si) , Zirconium (Zr) and Yttrium (Y) . Furthermore, it is very high Aluminum (Al) activity implies a large margin against loss of the ability to reform protective alumina. This very high Aluminum (Al) activity furthermore enables fast selective oxidation of AI2O3 leading to thin oxide scales which better resist spallation.

STAL18SiLaY is taken as the norm for high ability for crack free cladding in which the monocrystalline structure is retained into and within a monocrystalline substrate. This is provided by a moderate gamma prime content, and a significant addition of Silicon (Si) , which provides good wetting between the cladded layers .

STAL18SiLaY is taken as the norm for useful phase stability since no brittle phase formation has been seen in service when it has been used for repair of oxidation damaged monocrystalline blades.

STAL18SiLaY is taken as the norm for useful creep resistance based on its moderate level of strengthening elements, a gamma prime content of 37mol%, the beneficial single crystal structure obtained via cladding, and good service experience when it has been used for repair of oxidation damaged monocrystalline blades.

Hot corrosion resistance is provided by Chromium (Cr) and enhanced by Silicon (Si) . It is also important to allow at most a moderate Molybdenum (Mo) level.

D. Goldschmidt "Single-Crystal Blades Proc, from Materials for Advanced Power Engineering" 1994, Part I, p.661-674 teaches that the hot corrosion resistance of the blade alloy SCI 6 with 16wt% Chromium (Cr) and 3 wt% Molybdenum (Mo) is significantly inferior to that of the blade alloy IN738LC with 16wt% Chromium (Cr) and 1 . 8 wt% Molybdenum (Mo ) .

If the amount of alloy elements is too high, unwanted phases (UP ) such as Sigma and Laves phases will form in service . Therefore , an increased level of alloy elements other than Chromium ( Cr ) must be accompanied by a reduction in Chromium ( Cr ) if too much UP formation is to be avoided, implying a conflict between corrosion resistance and other properties . One particular effect of UP precipitation is a reduction in creep strength . Another is embrittlement of the blade alloy . Another is reduction of oxidation and corrosion resistance if Chromium ( Cr ) is tied up in Chromium ( Cr ) rich UP .

In the context of high firing temperature gas turbines , it is generally accepted that high oxidation resistance implies the ability to form an adherent and continuous A1₂O₃ layer in the oxide scale , as needed to withstand metal temperatures on or exceeding the 1000°C level . Furthermore , the oxide scale spallation caused by the always present sulfur contamination must be suppressed . Furthermore , there must be a margin against loss of the ability to reform protective alumina since each reformation implies a loss of Aluminum (Al ) . Furthermore , the use of alloy elements such as Titanium will cause contamination of the AI2O3 layer as Titanium partially substitutes for Aluminum (Al ) in said layer, rendering the layer less protective . Furthermore , it is beneficial to enable fast selective oxidation of A1₂O₃ as this will reduce the thickness of the oxide scale and make it less prone to spallation .

The ability for formation of protective AI2O3 , and the margin against loss of Aluminum (Al ) via scale spallation, is a complex function of the Aluminum (Al ) content and the combination of other alloy elements which, acting in synergy, enhance or reduce this ability . In Calculations for Phase Diagrams (CALPHAD ) terms this ability is associated with the predicted Aluminum (Al ) activity . In the context of blade alloys CALPHAD means use of thermodynamic software such as Thermocalc for prediction of entities such as partitioning of alloy elements between gamma and gamma prime ; liquidus , soli- dus and gamma prime solvus temperatures; gamma prime content; risk for precipitation of UP; Aluminum (Al) activity. An increased Aluminum (Al) activity also implies faster selective oxidation of protective A1₂O₃.

The following observations on alloy element additions for improved oxidation resistance can be found in the literature:

C.A. Barrett, "A Statistical Analysis of Elevated Temperature Gravimetric Cyclic Oxidation Data of 36 Ni- and Co- base Superalloys based on an Oxidation Attack Parameter NASA TM 105934" teaches that the ability to form protective A1₂O₃ is provided by Aluminum (Al) , enhanced by Chromium (Cr) and Tantalum (Ta) , somewhat reduced by Molybdenum (Mo) and Tungsten (W) , and significantly reduced by Titanium (Ti) and Niobium (Nb) . This was based on a large correlation study on commercial as well as experimental blade alloys. This implies that less Aluminum (Al) is needed to form a protective A1₂O₃ layer if the levels of Chromium (Cr) and Tantalum (Ta) are increased, or, the levels of Titanium (Ti) and Niobium (Nb) are reduced .

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 scale adherence is severely reduced by tramp elements such as S, but, that this effect can be neutralized by a combination of clean casting and addition of small measured levels of reactive elements (Rhenium (Re) ) . Without Rhenium (Re) additions it is necessary to be well below Ippmw Sulfur (S) to avoid a detrimental effect on the scale adherence.

B.A. Pint 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) underlines the importance of Sulfur (S) , and further teaches the beneficial Rhenium (Re) effects if small levels of Hafnium (Hf) and the rare earth Yttrium (Y) are combined. P. Caron et al. "Improvement of the Cyclic Oxidation Behaviour of Uncoated Nickel Based Single Crystal Superalloys Materials Proceedings" in 'Materials for Advanced Power Engineering 1994' teaches the beneficial Rhenium (Re) effects if small levels of Hafnium (Hf) and Silicon (Si) are combined.

B.A. Pint 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 Rhenium (Re) effects can be obtained when a multiple Rhenium (Re) recipe is used, one example being the excellent cyclic oxidation resistance seen in tests on Haynes- 214 which contained small levels of Zirconium (Zr) , Silicon (Si) and Yttrium (Y) .

J. B. Wahl, K. Harris "Advances in Single Crystal Superalloys - Control of Critical Elements Proceedings" '7th Parsons conference' , 2007, teaches the beneficial effect of 'Hafnium (Hf) plus a combination of Lanthanum and Yttrium (Y) ’, rather than 'Hafnium (Hf) plus Lanthanum or Yttrium (Y) , on the cyclic oxidation resistance of CMSX-4.

It is generally accepted that the risk for hot tearing during an additive manufacturing process such as laser cladding or powder bed fusion, and strain age cracking during a subsequent solutioning, increase with increasing gamma prime content. It is also generally accepted that cladding in which the monocrystalline structure is to be preserved presents a significant challenge. The cladding process itself does in principle enable monocrystalline growth as it creates a high temperature gradient from the melt pool into the comparatively cold substrate. In practice it is however difficult to suppress stray grain formation during the process. It is furthermore difficult to suppress strain age cracking for filler alloys having a high gamma prime content, and most filler alloys with a high oxidation resistance, associated with an ability to form protective A1₂O₃, have a high gamma prime content . Most blade alloys can be characterized as Classical Industrial Gas Turbine (IGT) alloys, Aero alloys or New IGT alloys, see Table 1. The class of Classical IGT alloys include the polycrystalline IN738LC, GTD-111, IN792, and the monocrystalline SCA425 (table 1)

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Table 1: Element additions in wt% , gamma prime content in mol% at 850°C, Al activity (relative values) at 1273K. Yttrium (Y) on Cr₂O₃ means protective Cr₂O₃ can be formed, n.a. means not applicable . These alloys have sufficient Chromium (Cr) for formation of protective Cr₂O₃.

Blade alloys which lack this ability have a comparatively poor corrosion resistance. The classical IGT blade alloys do not have the ability to form protective A1₂O₃ although SCA425 with 4wt% Aluminum (Al) supported by 16wt% Chromium (Cr) is border line. In house oxidation testing at 1273K has shown that SCA425 will form a continuous layer of A1₂O₃ on most but unfortunately not all its surface. Its Aluminum (Al) activity at 1273K is 3.1e-8 based on Thermocalc with TTN18 as data base. The Classical IGT alloys do not fulfil our objective since they are not able to form protective A1₂O₃.

The class of Aero alloys include the polycrystalline CM247CC, used for CC and DS casting, and the monocrystalline CMSX-4 and Rene N5, see Table 1. Their hot corrosion resistance is poor due to their low Chromium (Cr) levels. Most of them can form protective A1₂O₃ thanks to high levels of Aluminum (Al) and Tantalum (Ta) , and, despite low levels of Chromium (Cr) . The Aero alloys do not fulfil our objective since their corrosion resistance is poor. Furthermore, their high gamma prime contents, typically in the 60mol% to 70mol% range, imply that they are difficult to process by laser cladding.

The class of New IGT alloys include the polycrystalline STAL125CC1, the monocrystalline STAL15SX, the laser cladding alloy STAL18SiLaY aimed at cladding of monocrystalline substrates, and, the laser cladding alloy Edgel4 aimed at cladding of polycrystalline and directionally solidified blade alloys, see Table 1. These alloys have sufficient Chromium (Cr) for formation of protective Cr₂O₃ at low and intermediate temperatures, typically up to about 1173K. Furthermore, they form protective A1₂O₃ at high temperature, typically above about 1123K, thanks to moderate to high levels of Aluminum (Al) supported by significant levels of Chromium (Cr) and Tantalum (Ta) . A protective Cr₂O₃ layer on top of a protective A1₂O₃ layer is formed by STAL18SiLaY.

In STAL18SiLaY, the requirements on very high hot corrosion resistance, high oxidation resistance, good SX cladding capability, high phase stability and at least moderate creep resistance were met through the use of moderate levels of Aluminum (Al) and Tantalum (Ta) , a high level of Chromium (Cr) , a multiple Rhenium (Re) recipe, moderate levels of the matrix strengthening elements Molybdenum (Mo) and Tungsten (W) , a particular restriction on the level of Molybdenum (Mo) , and use of Silicon (Si) to enhance corrosion and oxidation resistance, and, to retain the monocrystalline structure into the cladded volume. The idea was that moderate levels of Aluminum (Al) and Tantalum (Ta) were sufficient to enable formation of an adherent continuous A1₂O₃ scale thanks to support from high levels of Chromium (Cr) , multiple Rhenium (Re) effects, and omission of detrimental elements like Titanium (Ti) and Niobium (Nb) . Therefore, the gamma prime content could be kept sufficiently low to allow for good weldability. Furthermore, moderate levels of gamma prime, and, of matrix and gamma prime strengthening elements enabled a sufficient creep strength for the intended application. Furthermore, high levels of Chromium (Cr) , a low level of Molybdenum (Mo) and the addition of Silicon (Si) enabled a very high hot corrosion resistance. Furthermore, a high level of Chromium (Cr) could be tolerated from a phase stability point of view because the gamma prime content and the amount of matrix strengthening elements were moderate.

In STAL18SiLaY crack free cladding can be achieved within a surprisingly wide process window despite the use of comparatively large weld seams in the 1mm to 2mm range in width and height. One reason is the moderate gamma prime content. Another reason, based on in-house trials with the same process parameters involving variants otherwise like STALlSSiLaY but differing in Silicon (Si) content, is that Silicon (Si) improves the wetting between layers, and, that this is instru- mental in retaining the monocrystalline structure. With less Silicon (Si) but similar levels of gamma prime particles and strengthening elements, new grains and cracks initiated in the interphases between cladding layers, and these cracks propagated along the so formed grain boundaries .

The recently developed New IGT cladding alloy Edgeli was developed for excellent oxidation resistance. Relative to the New IGT alloys above, Cobalt (Co) is omitted while Iron (Fe) is included. The high Aluminum (Al) content in Edgeli would normally have resulted in a high gamma prime content which would have made crack free cladding very difficult. The Iron (Fe) addition affects the partitioning of Aluminum (Al) , causing more Aluminum (Al) to be present in the gamma matrix. This means that a higher Aluminum (Al) content can be tolerated without making the gamma prime content too high for the alloy to be conveniently used for cladding. It also means that the concentration of Aluminum (Al) in the gamma matrix is increased. In CALPHAD terms this translates into an increased Aluminum (Al) activity. At 1273K the Aluminum (Al) activity of Edgel5 is 8.2*10"⁸ to be compared to STAL18SiLaY with an Aluminum (Al) activity of 4.9*10~⁸, STAL15SX with an Aluminum (Al) activity of 4.3*10~⁸ and SCA425 with an Aluminum (Al) activity of 3.1*10"⁸. It should be mentioned that STAL1SX has shown similar oxidation resistance to CMSX-4 in lab tests and in service while squealer tips in CMSX-4 blades repaired with STALlSSiLaY showed less oxidation damage than the initial CMSX-4 tips. It can be observed that the step in predicted Aluminum (Al) activity from STAL18SiLaY to Edgeli is significantly higher than the significant step from STAL15SX to STAL18SLaY, and the step from the border line SCA425 to STAL15SX with a high oxidation resistance proven in lab tests and in service.

Edgeli has been successfully applied by cladding onto CM247CC, and specimen comprising a cladded block of Edgeli onto a CM247CC substrate were subjected to oxidation testing. It turned out to be very difficult to provoke oxidation dam- age in Edgel 4 . Eventually a l OO Oh test with Ih hold times at 14523K was utilized ( higher levels would have caused incipient melting in CM247CC ) . The Edgel5 material was still only mildly affected while the CM247CC substrate was to a significant degree destroyed . Edgel4 thus provides excellent oxidation resistance . It can be observed that the excellent oxidation resistance correlates well with the very high Aluminum (Al ) activity .

Of these new IGT alloys , only STAL18SiLaY has the combination of at most moderate gamma prime content and a significant Silicon ( Si ) addition which enables a high ability for crack free cladding such that the monocrystalline structure in a monocrystalline substrate is retained into and within the cladded area . STAL18SiLaY does not , however, provide an Aluminum (Al ) activity consistent with the excellent oxidation resistance seen in Edgel 4 .

It is therefore the aim of the invention to overcome these problems .

The problems are solved by an alloy according claim 1 , a component according to claim 14 and a method according to claim 17 .

It is an obj ective of this invention to provide a gamma prime strengthened nickel-base superalloy, from here on referred to as a blade alloy, with a unique blend of high hot corrosion resistance , excellent oxidation resistance , a high ability for crack free cladding in which the monocrystalline structure in a substrate is retained, an useful phase stability, and useful creep resistance . This blend is useful for repair of oxidation damaged monocrystalline components , and, for fabrication of hybrid monocrystalline components when used to preempt oxidation damage . The cladded areas will furthermore have high resistance to hot corrosion caused by corrosive agents such as corrosive biofuels , or sea salt in the inlet air . The cladded area will furthermore not crack due to brit- tie phase formation. The cladded area will furthermore be able to manage the moderate creep loadings typically seen in areas such as edges and tips on monocrystalline components in which oxidation damage tends to occur.

It is an objective of this invention to provide a blend of high hot corrosion resistance, excellent oxidation resistance, good ability for crack free cladding in which the SX structure in a SX substrate is retained, useful phase stability, and a useful creep resistance. In particular, the objective is to significantly improve the oxidation resistance relative to STAL18SiLaY while keeping the same levels of SX cladding capability, phase stability and creep resistance. In this context a moderate reduction down to 'IN738LC level’ hot corrosion resistance can be accepted.

The present invention relates to a nickel-base gamma prime strengthened superalloy, containing between 2. Owt% and 9. Owt% Cobalt (Co) , between 3.0wt% and 9.0 wt% Iron (Fe) , between 14.0wt% and 18.0wt% Chromium (Cr) , between 2.0wt% and 5.0wt% of Molybdenum (Mo) + Tungsten (W) + Rhenium (Re) , at most 2.0wt% Molybdenum (Mo) , between 4.5wt% and 5.3 wt% Aluminum (Al) , between 3.0wt% and 7.0wt% Tantalum (Ta) , between 0.02wt% and 0.3wt% of Carbon (C) + Zirconium (Zr) + Boron (B) , at least 0.01wt% Carbon (C) , at least O.Olwti Zirconium (Zr) , between 0.05wt% and 1.0wt% Hafnium (Hf ) , between 0.3wt% and 0.7wt% Silicon (Si) and between 0.05wt% and 0.3wt% of the sum of rare earths such as Sc, Yttrium (Y) , the Actinides and the Lanthanides.

In the present invention, a judicious combination of Iron (Fe) and Cobalt (Co) is used to improve the oxidation resistance significantly relative to STAL18SiLaY via a very significantly increased Aluminum (Al) activity. When Iron (Fe) and Cobalt (Co) are added, Aluminum (Al) can be increased while the gamma prime content is kept on the same level thanks to the ability of the Iron (Fe) + Cobalt (Co) addition to affect the partitioning of Aluminum (Al) . When Aluminum (Al) is thus forced into the gamma matrix, Chromium (Cr) must be moderately reduced to avoid an increased propensity for UP formation. This is exemplified by the embodiments STAL17FeSiLaY, STAL16FeSiLaY and STAL15FeSiLaY in table 1. ThermoCalc simulation predicts a gamma prime content of 37mol% at an equilibrium temperature of 1123K for all cladding alloys in table 1. This is low enough to suggest good processability by cladding, but not so low as to suggest poor creep strength. Furthermore, the creep strength benefits from the SX structure. It should be noted that the 'replace Cobalt (Co) by Fe ' recipe used to design Edgel4 has been updated to a more efficient 'replace Cobalt (Co) by a judicious combination of Cobalt (Co) and Fe ' recipe in the present invention. As the Cobalt (Co) + iron (Fe) levels increase, so does the predicted Aluminum (Al) activity. Relative to STAL18SiLaY, Chromium (Cr) has been reduced. Nevertheless, the Chromium (Cr) content is well above the classical 12.0wt% Chromium (Cr) limit, Silicon (Si) has been added and Molybdenum (Mo) is kept low in order to achieve a high hot corrosion resistance .

The invention also comprises (in wt%) : 2.0% to 10.0% Cobalt (Co) , 3.0% to 10.0% Iron (Fe) , 14.0% to 18.0% Chromium (Cr) , 4.5% to 5.3% Aluminum (Al) , 3.0% to 7.0% Tantalum (Ta) , 0.01% to 0.05% Carbon (C) , 0.01% to 0.05% Zirconium (Zr) , 0.05% to 1.0% Hafnium (Hf ) , 0.3% to 0.7% Silicon (Si) , 0.01% to 0.3% of the sum of rare earths such as Scandium (Sc) , Yttrium (Y) , the Actinides and/or the Lanthanides, Nickel (Ni ) , optionally : up to 3.0% Tungsten (W) , especially 0.5% to 3.0% Tungsten (W) , and/ or up to 2.0% Molybdenum (Mo) , especially 0.4% to 2.0% Molybdenum (Mo) , and/ or up to 2.0% Rhenium (Re) , especially 0.3% to 2.0% Rhenium (Re) and/ or at most 0.05% Boron (B) , especially 0.01% to 0.05% Boron (B) .

Relative to Edgel4, the sole addition of Yttrium (Y) has been replaced by a multiple rare earth addition. Furthermore, the Silicon (Si) content is significantly increased. The more efficient use of Cobalt (Co) + Iron (Fe) has also enabled a very high Aluminum (Al) activity despite a lower Aluminum (Al) content. This reduction in Aluminum (Al) has resulted in a reduced gamma prime content as needed for convenient cladding of monocrystalline substrates resulting in a monocrystalline cladded area.

It might seem surprising that moderately increased Aluminum (Al) contents can increase the Aluminum (Al) activity. However, the oxidation resistance and the Aluminum (Al) activity are associated with the Aluminum (Al) content in the gamma matrix, and this is comparatively low even in blade alloys capable of forming protective A1₂O₃ since most of the Aluminum (Al) normally partitions to the gamma prime particles. The relative increase in gamma matrix Aluminum (Al) content, as Cobalt (Co) and Iron (Fe) force more Aluminum (Al) into said gamma matrix, is substantial.

According to the invention the alloy may include between 2. Owt% and 10.0wt% Cobalt (Co) , between 3.0wt% and 10.0wt% Iron (Fe) , between 14.0wt% and 18.0wt% Chromium (Cr) , between 2. Owt% and 5. Owt% of Molybdenum (Mo) + Tungsten (W) + Rhenium (Re) , at most 2.0 wt% Molybdenum (Mo) , between 4.5wt% and 5.3wt% Aluminum (Al) , between 3.0wt% and 7.0wt% Tantalum (Ta) , between O.Olwti and 0.3wt% of Carbon (C) + Zirconium (Zr) + Boron (B) , at least 0.01wt% Carbon (C) , at least O.OlwtY Zirconium (Zr) , between 0.05wt% and 1. Owt% Hafnium (Hf ) , between 0.3wt% and 0.7wt% Silicon (Si) and between O.Olwtt and 0.3wt% of the sum of rare earths such as Scandium (Sc) , Yttrium (Y) , the Actinides and the Lanthanides.

Additionally, the alloy may include between 2. Owt% and 4. Owt% Cobalt (Co) , between 3.0wt% and 4.5wt% Iron (Fe) , between 16.5 and 18.0wt% Chromium (Cr) , between 0.6wt% and 1. Owt% Molybdenum (Mo) , between 2. Owt% and 3. Owt% Tungsten (W) , between 4.5wt% and 4.9wt% Aluminum (Al) , between 3.5wt% and 5.5wt% Tantalum (Ta) , between O.Olwti and 0.05 wt% Carbon (C) , between O.Olwti and 0.05wt% Zirconium (Zr) , between 0.05wt% and 0.15wt% Hafnium (Hf ) , between 0.3wt% and 0.7wt% Silicon (Si) , between 0.03wt% and 0.13wt% Lanthanum (La) and 0.03 and 0.13wt% Yttrium (Y) .

In a preferred embodiment called STAL17FeSiLaY, the alloy may include 3.0wt% Cobalt (Co) , 4.0wt% Iron (Fe) , 17.0 wt% Chromium (Cr) , 0.8wt% Molybdenum (Mo) , 2.5wt% Tungsten (W) , 4.7wt% Aluminum (Al) , 4.5wt% Tantalum (Ta) , 0.03wt% Carbon (C) , 0.03wt% Zirconium (Zr) , 0. lwt% Hafnium (Hf ) , 0.5wt% Silicon (Si) , 0. lwt% Lanthanum (La) and 0. lwt% Yttrium (Y) .

Alternatively, the alloy may include between 3.0wt% and

5.0wt% Cobalt (Co) , between 5.5wt% and .5wt% Iron (Fe) , between 15.5wt% and 17.5wt% Chromium (Cr) , between 0.6wt% and 1.0wt% Molybdenum (Mo) , between 2.0wt% and 3.0wt% Tungsten (W) , between 4.6wt% and 5. lwt% Aluminum (Al) , between 3.5wt% and 5.5wt% Tantalum (Ta) , between 0.01wt% and 0.05wt% Carbon (C) , between 0.01wt% and 0.05wt% Zirconium (Zr) , between 0.05wt% and 0.15wt% Hafnium (Hf ) , between 0.3wt% and 0.7wt% Silicon (Si) , and 0.03wt% to 0.13wt% Lanthanum (La) and 0.03wt% to 0.13wt% Yttrium (Y) .

In a preferred embodiment called STAL16FeSiLaY, the alloy may include 4.0wt% Cobalt (Co) , 6.0wt% Iron (Fe) , 16.0wt% Chromium (Cr) , 0.8wt% Molybdenum (Mo) , 2.5wt% Tungsten (W) , 4.9wt% Aluminum (Al) , 4.5wt% Tantalum (Ta) , 0.03wt% Carbon (C) , 0.03wt% Zirconium (Zr) , 0.1wt% Hafnium (Hf ) , 0.5 wt% Silicon (Si) , 0.1 wt% Lanthanum and 0.1 wt% Yttrium (Y) .

Alternatively, the alloy may include between 6.0wt% and 9.0wt% Cobalt (Co) , between 7.5wt% and 9.0wt% Iron (Fe) , between 14.5wt% and 15.5wt% Chromium (Cr) , between 0.5wt% and 1.0wt% Molybdenum (Mo) , between 2.0wt% and 3.0wt% Tungsten (W) , between 4.8wt% and 5.2wt% Aluminum (Al) , between 3.5wt% and 5.5wt% Tantalum (Ta) , between 0.01wt% and 0.05wt% Carbon (C) , between 0.01wt% and 0.05wt% Zirconium (Zr) , between 0.05wt% and 0.15wt% Hafnium (Hf ) , between 0.3wt% and 0.7wt% Silicon (Si) , and 0.03wt% to 0.13wt% Lanthanum (La) and 0.03wt% to 0.13wt% Yttrium (Y) .

In a preferred embodiment called STAL15FeSiLaY, the alloy may include 8. Owt% Cobalt (Co) , 8. Owt% Iron (Fe) , 15.0wt% Chromium (Cr) , 0.8wt% Molybdenum (Mo) , 2.5wt% Tungsten (W) , 5. Owt% Aluminum (Al) , 4.5wt% Tantalum (Ta) , 0.03wt% Carbon (C) , 0.03wt% Zirconium (Zr) , O.lwti Hafnium (Hf ) , 0.5wt% Silicon (Si) , O.lwti Lanthanum and 0. lwt% Yttrium (Y) .

The blade alloy according to the invention is preferably processed with a clean production process. To guarantee best results, the blade alloy should contain less than 5ppm Sulfur (S) , preferably less than Ippm Sulfur (S) .

The alloy is preferably used for manufacturing a blade, a vane, heat shield or disc.

The alloy is suitable to be casted (e.g. , equiaxed) and is preferably casted in a single-crystal (SX) or a columnar (DS) microstructure .

For the latter a temperature gradient is used.

The alloy can be used as powder for additive manufacturing.

This can be welding using powder or a wire made of this alloy or generally a cladding method e.g. , welding,... is used.

Also powder bed methods are preferably used. The alloy can therefore be used to manufacture a whole component or partially .

This can preferably be used during manufacturing a new part . Also preferably possible is a method to repair a component , wherein the alloy is used .

In this case the alloy is added to substrate . The substrate can have preferably a SX or DS structure .

Especially in this case the added material (powder bed, clad- ding ) is build up also in a SX or DS structure .

Alternatively, further embodiments can be designed to optimize compatibility with specific coatings when the alloy is used as a base alloy . Alternatively, further embodiments can be designed to optimize compatibility with specific base alloys and coatings when the alloy is used as filler alloy for cladding and weld repair .

Claims

Patent claims

1. A nickel base superalloy, comprising (in wt%) :

2.0% to 10.0% Cobalt (Co) ,

3.0% to 10.0% Iron (Fe) ,

14.0% to 18.0% Chromium (Cr) ,

4.5% to 5.3% Aluminum (Al) ,

3.0% to 7.0% Tantalum (Ta) ,

0.01% to 0.05% Carbon (C) ,

0.01% to 0.05% Zirconium (Zr) ,

0.05% to 1.0% Hafnium (Hf ) ,

0.3% to 0.7% Silicon (Si) ,

0.01% to 0.3% of the sum of rare earths such as Scandium

(Sc) , Yttrium (Y) , the Actinides and/or the Lanthanides, Nickel (Ni) , especially remainder Nickel (Ni) , optionally: up to 3.0% Tungsten (W) , especially 0.5% to 3.0% Tungsten (W) , and/ or up to 2.0% Molybdenum (Mo) , especially 0.4% to 2.0% Molybdenum (Mo) , and/ or up to 2.0% Rhenium (Re) , especially 0.3% to 2.0% Rhenium (Re) and/ or at most 0.05% Boron (B) , especially 0.01% to 0.05% Boron (B) .

2. Alloy according to claim 1, comprising

2.0% to 5.0% of Molybdenum (Mo) and/or Tungsten (W) and/or Rhenium (Re) , especially comprising Molybdenum (Mo) and Tungsten (W) and not Rhenium (Re) . 3. Alloy according to one of the claims 1 or 2,

0.02% to 0.2% of Carbon (C) and/or Zirconium (Zr) and/or

Boron (B) . especially Carbon (C) and Zirconium (Zr) , very especially Carbon (C) and Zirconium (Zr) and Boron (B) .

4. Alloy according to any of the claims 1, 2 or 3,

2.0% to 4.0% Cobalt (Co) ,

3.0% to 4.5% Iron (Fe) ,

16.5% to 18.0% Chromium (Cr) ,

0.6% to 1.0% Molybdenum (Mo) ,

2.0% to 3.0% Tungsten (W) ,

4.5% to 4.9% Aluminum (Al) ,

3.5% to 5.5% Tantalum (Ta) ,

0.01% to 0.05% Carbon (C) ,

0.01% to 0.05% Zirconium (Zr) ,

0.05% to 0.15% Hafnium (Hf ) ,

0.3% to 0.7% Silicon (Si) ,

0.03% to 0.13% Lanthanum (La) and

0.03% to 0.13% Yttrium (Y) .

5. Alloy according to any of the claims 1, 2, 3 or 4,

3.0% Cobalt (Co) ,

4.0% Iron ( Fe ) ,

17.0% Chromium (Cr) ,

0.8% Molybdenum (Mo) ,

2.5% Tungsten (W) ,

4.7% Aluminum (Al) ,

4.5% Tantalum (Ta) ,

0.03% Carbon (C) ,

0.03% Zirconium (Zr) ,

0.1% Hafnium (Hf ) ,

0.5% Silicon (Si) ,

0.1% Lanthanum (La) ,

0.1% Yttrium (Y) . 6. Alloy according to claim 1, 2 or 3, 3.0% to 5.0% Cobalt (Co) ,

5.5% to 6.5% Iron (Fe) , 15.5% to 17.5% Chromium (Cr) , 0.6% to 1.0% Molybdenum (Mo) , 2.0% to 3.0% Tungsten (W) , 4.6% to 5.1% Aluminum (Al) , 3.5% to 5.5% Tantalum (Ta) , 0.01% to 0.05% Carbon (C) , 0.01% to 0.05% Zirconium (Zr) , 0.05% to 0.15% Hafnium (Hf ) , 0.3% to 0.7% Silicon (Si) , 0.03% to 0.13% Lanthanum (La) and 0.03% to 0.13% Yttrium (Y) .

7. Alloy according to claim 1 or 6, 4.0% Cobalt (Co ) ,

6.0% Iron ( Fe) , 16.0% Chromium (Cr) , 0.8% Molybdenum (Mo) , 2.5% Tungsten (W) , 4.9% Aluminum (Al) , 4.5% Tantalum (Ta) , 0.03% Carbon (C) , 0.03% Zirconium (Zr) , 0.1% Hafnium (Hf ) , 0.5% Silicon (Si) , 0.1% Lanthanum (La) and 0 .1% Yttrium (Y) .

8. Alloy according to any of the claims 1, 2 or 3 , 6.0% to 9.0% Cobalt (Co) ,

7.5% to 9.0% Iron (Fe) , 14.5% to 15.5% Chromium (Cr) , 0.5% to 1.0% Molybdenum (Mo) , 2.0% to 3.0% Tungsten (W) , 4.8% to 5.2% Aluminum (Al) ,

3.5% to 5.5% Tantalum (Ta) ,

0.01% to 0.05% Carbon (C) ,

0.01% to 0.05% Zirconium (Zr) ,

0.05% to 0.15% Hafnium (Hf ) ,

0.3% to 0.7% Silicon (Si) ,

0.03% to 0.13% Lanthanum (La) and

0.03% to 0.13% Yttrium (Y) .

9. Alloy according to any of the claims 1, 2, 3 or 8, comprising

8.0% Cobalt (Co ) ,

8.0% Iron ( Fe ) ,

15.0% Chromium (Cr) ,

0.8% Molybdenum (Mo) ,

2.5% Tungsten (W) ,

5.0% Aluminum (Al) ,

4.5% Tantalum (Ta) ,

0.03% Carbon (C) ,

0.03% Zirconium (Zr) ,

0.1% Hafnium (Hf ) ,

0.5% Silicon (Si) ,

0.1% Lanthanum (La) and

0.1% Yttrium (Y) .

10. Alloy according to any of the claims 1, 2, 3, comprising (in wt%) :

6.0% to 9.0% Cobalt (Co)

7.5% to 9.0% Iron (Fe)

14.5% to 15.5% Chromium (Cr)

0.6% to 1.0% Molybdenum (Mo)

2.0% to 3.0% Tungsten (W)

4.8% to 5.2% Aluminum (Al)

3.5% to 5.5% Tantalum (Ta)

0.01% to 0.05% Carbon (C)

0.01% to 0.05% Zirconium (Zr)

0.005% to 0.015% Boron (B)

0.05% to 0.15% Hafnium (Hf)

0.3% to 0.7% Silicon (Si)

0.03% to 0.13% Lanthanum (La)

0.03% to 0.13% Yttrium (Y) .

11. Alloy in claim 10, comprising (in wt%) : 8.0% Cobalt (Co)

8.0% Iron (Fe) 15.0% Chromium (Cr) 0.8% Molybdenum (Mo) 2.5% Tungsten (W) 5.0% Aluminum (Al) 4.5% Tantalum (Ta) 0.03% Carbon (C) 0.03% Zirconium (Zr) 0.01% Boron (B) 0.1% Hafnium (Hf) 0.5% Silicon (Si) 0.1% Lanthanum (La) 0.1% Yttrium (Y) .

12. Alloy according to any of the claims 1, 2, 3, comprising (in wt%) :

6.0% to 9.0% Cobalt (Co)

7.5% to 9.0% Iron (Fe)

14.5% to 15.5% Chromium (Cr)

0.6% to 1.0% Molybdenum (Mo)

2.0% to 3.0% Tungsten (W)

4.65% to 5.05% Aluminum (Al)

3.5% to 5.5% Tantalum (Ta)

0.01% to 0.05% Carbon (C)

0.01% to 0.05% Zirconium (Zr) 0.35% to 0.65% Hafnium (Hf) 0.3% to 0.7% Silicon (Si) 0.03% to 0.13% Lanthanum (La) 0.03% to 0.13% Yttrium (Y) .

13. Alloy according to claim 12, comprising (in wt%) :

8.0% Cobalt (Co) 8.0% Iron (Fe) 15.0% Chromium (Cr) 0.8% Molybdenum (Mo) 2.5% Tungsten (W) 4.85% Aluminum (Al) 4.5% Tantalum (Ta) 0.03% Carbon (C) 0.03% Zirconium (Zr) 0.5% Hafnium (Hf) 0.5% Silicon (Si) 0.1% Lanthanum (La) 0.1% Yttrium (Y) .

14. Component, especially for gas turbines, which comprises an alloy according to any of the claims 1 to 13,

15. Component according to claim 14, which is a blade, a vane, heat shield or disc.

16. Component according to claim 14 or 15, which has a single-crystal (SX) or a columnar (DS) microstructure . 17. Method to produce a component, especially a component of claim 14, 15 or 16, wherein an alloy according to any of the claims 1 to 13 is used.

18. Method according to claim 17, wherein the component is casted, especially wherein temperature gradients are used.

19. Method according to claim 17, wherein an additive build up is used, especially a cladding method or a powder bed method is used .

20. Method according to claim 17 or 19, to repair a component, wherein the alloy according to any of the claims 1 to 13 is used to repair a substrate, which has especially a SX or DS structure, and wherein especially also a SX or DS structure is build up.