Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
  • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
  • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
  • C22C19/056—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 10% but less than 20%
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/17—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by forging
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F5/009—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of turbine components other than turbine blades
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F5/04—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of turbine blades
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/04—Making non-ferrous alloys by powder metallurgy
  • C22C1/0433—Nickel- or cobalt-based alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
  • F01D25/005—Selecting particular materials
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
  • F01D5/12—Blades
  • F01D5/28—Selecting particular materials; Particular measures relating thereto; Measures against erosion or corrosion
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/24—After-treatment of workpieces or articles
  • B22F2003/248—Thermal after-treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2207/00—Aspects of the compositions, gradients
  • B22F2207/11—Gradients other than composition gradients, e.g. size gradients
  • B22F2207/13—Size gradients
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/20—Manufacture essentially without removing material
  • F05D2230/25—Manufacture essentially without removing material by forging
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/40—Heat treatment
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/40—Heat treatment
  • F05D2230/42—Heat treatment by hot isostatic pressing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/17—Alloys
  • F05D2300/175—Superalloys
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/60—Properties or characteristics given to material by treatment or manufacturing
  • F05D2300/609—Grain size
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/70—Treatment or modification of materials
  • F05D2300/701—Heat treatment

Definitions

• the present invention relates to the field of nickel-based superalloys for high temperature applications and developed for a turbine disk application with a dual coarse-grain/fine-grain structure.
• Increasing engine performance and reducing their specific consumption requires an increase in their operating temperature. This translates into the need to have new materials that are ever more resistant to heat.
• the target temperatures are around 800°C in nominal operation with temporary peaks of up to 850°C in the rim of the disk, i.e. near the blades.
• the alloy must also be very resistant in traction and fatigue in the area near the disc bore, because it is subject to high stresses when the complete disc + turbine blade system is rotating, but at lower temperatures (below 700°C).
• the process path which includes, among other things, the development of the alloy by powder metallurgy and the application of a dual structure heat treatment (patent FR3043410B1) allowing to optimize the grain size both in the rim and in the bore of the disc, and on the other hand the material route which makes it possible to have a chemical composition directly adapted to this process and to achieve a significant gain on mechanical properties.
• the process route which includes, among other things, the production of the alloy by powder metallurgy and the application of a treatment thermal with dual structure (patent FR3043410B1) to optimize the grain size both in the rim and in the disc bore;
• the temperature is higher than the dissolution temperature of the phase blocking the grain boundaries, also called solvus temperature (for gamma-gamma prime nickel base alloys, the phase in question is the gamma phase prime).
• the temperature is lower than this solvus temperature.
• the grains will grow to form a structure favorable to creep and cracking properties, while in zones whose heat treatment temperature will remain lower than the solvus temperature, the structure will retain the grain size resulting from forging which is generally relatively fine and favorable for tensile and fatigue properties.
• the application of a gradient treatment is carried out on an existing “classic” alloy whose chemical composition has been optimized to achieve, with a homogeneous structure over the entire part, the best compromise of mechanical properties required.
• the superalloys for The highest performance drives have a target operating temperature of 760°C, with possible peaks at 800°C.
• existing chemical compositions are not optimal for configuring a gradient treatment. Improving the performance of the part therefore requires defining a chemical composition specific to a gradient treatment of the part.
• a nickel-based alloy composition was jointly defined by Safran Tech and ONERA to provide a first response to this problem (patent application FR3104613A1).
• This alloy has been specifically designed for a turbine disk application with a dual structure, where the grain size is optimized according to the mechanical characteristics required in each area of the part: the bore has a fine grain microstructure to optimize its resistance in traction and its fatigue life, while the rim has a larger grain microstructure to optimize its resistance to creep and crack propagation.
• the coarse-grained microstructure is obtained through local supersolvus y' (gamma prime) heat treatment.
• This alloy has a density of 8.24 g/cm 3 , which is rather low compared to other known alloys (8.34 g/cm 3 for the powder metallurgy alloy N19) and therefore very interesting for this type of application.
• this composition has a relatively narrow supersolvus y' (gamma prime) heat treatment window: there is only about ten degrees of difference between the solvus y' (gamma prime) and the solidus of the alloy. . From an industrial point of view, this heat treatment is feasible but the margin for error is small. Furthermore, even if the creep resistance at 850°C of this alloy is very interesting, there are levers to optimize it in order to further increase the lifespan of the parts at this extreme temperature.
• Niobium Another nickel-based alloy composition was already known from the prior art (application EP1840232) with higher nickel contents. niobium. However, their higher Nb content does not allow the precipitation of M23C6 carbides at a temperature of 850 °C which remain stable up to 900 °C or even 920 °C because Nb lowers the solvus temperature of these carbides below 900 °C. C, or even below 800°C. However, such carbides improve the creep resistance of the alloy.
• the present invention therefore relates to a nickel-based superalloy, characterized in that its composition comprises, advantageously consists essentially of, in particular consists of, in percentages by weight of the total composition:
• Cobalt 7.9 - 16.9, advantageously 8.2 - 16.6;
• Chromium 9.7 - 13.1, advantageously 10.0 - 12.8;
• Molybdenum 2.6 - 4.1, advantageously 2.6 - 3.8;
• Niobium 0 - 0.41
• Tantalum 0 - 1.9, advantageously 0 - 1.8;
• Titanium 4.4 - 6.4, advantageously 4.6 - 6.1;
• Tungsten 1.9 - 4.2, advantageously 2.2 - 4.0;
• Carbon 0.010 - 0.040, advantageously 0.015 - 0.035;
• Hafnium 0.20 - 0.40, advantageously 0.20 - 0.35;
• Zirconium 0.040 - 0.070, advantageously 0.045 - 0.065;
• Nickel balance as well as inevitable impurities; with 12.5 ⁇ Al + Ti + Nb + Ta ⁇ 14% at., the contents of these elements being expressed in atomic percentages; with 0.85 ⁇ Al / (Ti + Nb + Ta) ⁇ 1.2, the contents of these elements being expressed in atomic percentages; and with Mo + W > 2.5% at., the contents of these elements being expressed in atomic percentages.
• composition of the nickel-based superalloy according to the invention therefore contains the following elements:
• composition according to the invention thus comprises, in % by weight relative to the total weight of the composition, aluminum (Al) in a content included in the range 2.5 - 3.8, advantageously 2.8 - 3 .5, in particular 2.82 - 3.43, more particularly 2.9 - 3.3.
• Al content is measured with an uncertainty of ⁇ 0.10.
• composition according to the invention further comprises, in % by weight relative to the total weight of the composition, cobalt (Co) in a content included in the range 7.9 - 16.9, advantageously 8.2 - 16, 6, especially 8.2 - 15.6, more particularly 12.0 - 14.0.
• cobalt content is measured with an uncertainty of ⁇ 0.4.
• composition according to the invention further comprises, in % by weight relative to the total weight of the composition, chromium (Cr) in a content included in the range 9.7 - 13.1, advantageously 10.0 - 12, 8, in particular 10.8 - 12.8, more particularly 10.9 - 12.7, even more particularly 11.65 - 12.7.
• Cr chromium
• the composition according to the invention further comprises, in % by weight relative to the total weight of the composition, molybdenum (Mo) in a content included in the range 2.6 - 4.1, advantageously 2.6 - 3, 8, in particular 2.7 - 3.25.
• Mo molybdenum
• the molybdenum content is measured with an uncertainty of ⁇ 0.11.
• the composition according to the invention further comprises, in % by weight relative to the total weight of the composition, niobium (Nb) in a content included in the range 0 - 0.41.
• the composition is free of niobium.
• the composition contains niobium in an amount of at most 0.41% (in % by weight relative to the total weight of the composition), in particular in the range 0.39 - 0. 41%, more specifically 0.40 - 0.41%.
• the niobium content is measured with an uncertainty of ⁇ 0.10.
• the composition according to the invention further comprises, in % by weight relative to the total weight of the composition, tantalum (Ta) in a content included in the range 0 - 1.9, advantageously 0 - 1.8.
• the composition is free of tantalum.
• tantalum (Ta) contributes to the strengthening of the gamma prime phase but has the effect of increasing the density of the alloy.
• the composition contains tantalum in an amount of at most 1.9% (in % by weight relative to the total weight of the composition), in particular at most 1.6%, more particularly in the range 1 - 1.6%.
• the tantalum content is measured with an uncertainty of ⁇ 0.15.
• composition according to the invention further comprises, in % by weight relative to the total weight of the composition, titanium (Ti) in a content included in the range 4.4 - 6.4, advantageously 4.6 - 6, 1.
• Ti titanium
• the titanium content is measured with an uncertainty of ⁇ 0.15.
• the composition according to the invention further comprises, in % by weight relative to the total weight of the composition, tungsten (W) in a content included in the range 1.9 - 4.2, advantageously 2.2 - 4, 0.
• the tungsten content is measured with an uncertainty of ⁇ 0.16.
• the composition according to the invention also comprises, in % by weight relative to the total weight of the composition, boron (B) in a content included in the range 0.010 - 0.030, in particular 0.010 - 0.020.
• the boron content is measured with an uncertainty of ⁇ 0.003.
• the composition according to the invention also comprises, in % by weight relative to the total weight of the composition, carbon (C) in a content included in the range 0.010 - 0.040, advantageously 0.015 - 0.035, in particular 0.020 - 0.035.
• the carbon content is measured with an uncertainty of ⁇ 0.003.
• composition according to the invention further comprises, in % by weight relative to the total weight of the composition, hafnium (Hf) in a content in the range 0.20 - 0.40, advantageously 0.20 - 0.35 .
• hafnium content is measured with an uncertainty ⁇ 0.002.
• the composition according to the invention further comprises, in % by weight relative to the total weight of the composition, zirconium (Zr) in a content in the range 0.040 - 0.070, advantageously 0.045 - 0.065, in particular 0.055 - 0.060.
• the zirconium content is measured with an uncertainty of ⁇ 0.003.
• the nickel-based alloy according to the invention contains the elements cobalt, aluminum, titanium, niobium and tantalum intended to form a hardening Y' (gamma prime) precipitation of ordered structure Ll 2 and of composition (Ni,Co) 3 ( AI,Ti,Nb,Ta).
• the tantalum content is however limited in order to avoid excessively increasing the density of the alloy, the target of which is less than or equal to 8.30 g/cm 3 .
• the presence of too high a quantity of niobium results in a lowering of the solvus temperature of the M 23 C 6 carbides below 900 °C.
• the minimum solvus value of the M 23 C ⁇ carbides is thus advantageously fixed at 900 °C (solvus M 23 C ⁇ > 900 °C), preferably at 920 °C (solvus M 2 3C 6 > 920 °C), in order to ensure their stability at 850 °C and to maintain a margin in the event of a future increase in the temperature peaks of the disks in functioning.
• Carbon, boron, zirconium and hafnium strengthen the strength of grain boundaries at high temperatures. Carbon also makes it possible to form M23C6 carbides (with M Cr, Mo or W).
• the hot mechanical strength of the alloy is favored by a mole fraction of precipitates y' (gamma prime) of between 50% and 56%.
• the elements Al, Ti, Nb and Ta expressed in atomic percentages respect the criterion 12.5 ⁇ Al + Ti + Nb + Ta ⁇ 14% at..
• the elements Al, Ti, Nb and Ta In order to favor the precipitation of the y' phase (gamma prime) compared to the q-Ni 3 Ti phase, undesirable from the point of view of mechanical properties, the elements Al, Ti, Nb and Ta respect the criterion 0.85 ⁇ Al / (Ti + Nb + Ta) ⁇ 1.2, the contents of these elements being expressed in atomic percentages.
• the unavoidable impurities of the composition according to the invention come from the stages of manufacturing the superalloy or from the impurities present in the raw materials used for the manufacture of the superalloy.
• the nickel-based superalloy according to the invention is characterized in that its composition comprises, advantageously consists essentially of, in particular consists of, in percentages by weight of the total composition: Aluminum: 2, 8 - 3.5;
• Chromium 10.8 - 12.8;
• Molybdenum 2.7 - 3.25;
• Niobium 0 - 0.41
• Tantalum 0 - 1.9;
• Titanium 4.6 - 6.1;
• Tungsten 2.2 - 4.0;
• Carbon 0.010 - 0.040, advantageously 0.015 - 0.035; Hafnium: 0.20 - 0.40, advantageously 0.20 - 0.35;
• Zirconium 0.040 - 0.070, advantageously 0.045 - 0.065;
• Nickel balance as well as inevitable impurities; with 12.5 ⁇ Al + Ti + Nb + Ta ⁇ 14% at., the contents of these elements being expressed in atomic percentages; with 0.85 ⁇ Al / (Ti + Nb + Ta) ⁇ 1.2, the contents of these elements being expressed in atomic percentages; and with Mo + W > 2.5% at., the contents of these elements being expressed in atomic percentages.
• composition of the superalloy according to the present invention can be as indicated in the following Table 1.
• the superalloy according to the invention has a density of less than 8.50 g/cm 3 , advantageously less than 8.30 g/cm 3 .
• the room temperature density of each superalloy was estimated using a modified version of the Hull formula. This empirical equation was proposed by Hull (FC Hull, Metal Progress, November 1969, ppl39-140). The empirical equation is based on the law of mixtures and includes corrective terms deduced from a linear regression analysis of experimental data (chemical compositions and measured densities) concerning 235 superalloys and stainless steels. This Hull formula was modified from data relating to 272 nickel-based, cobalt-based and iron-based superalloys. The modified Hull formula is as follows:
• D- -100-/ [S ⁇ (%X/DX)]-+- 1 -AX-x-%X
• DX are the densities of the elements X (Cr, Ni, etc...)
• D is the density of the superalloy, the densities being expressed in g/cm 3
• AX is a coefficient expressed in g/cm 3 of the elements X (Cr, Ni, etc.)
• ANi -0.0011
• AAI 0.0622
• ANb 0.011
• ACo -0.0001
• ACr -0.0034
• AMo 0.0033
• AW 0.0033
• AHf 0.0156
• %X are the contents, expressed in mass percentages, of the elements X of the superalloy (Cr, Ni, etc.).
• the superalloy according to the invention has metallurgical stability (that is to say an absence of TCP phases - Topological Compact Phases) up to 800 - 850 ° C.
• the superalloy according to the invention has good resistance to oxidation.
• the superalloy according to the invention has a difference between the solidus temperature y (gamma) and the solvus temperature y' (gamma prime) sufficiently large for carrying out the heat treatment, advantageously a difference at least 20 °C ([solidus y - solvus y'] - 20 °C).
• the nickel-based superalloy according to the invention is free of tantalum and/or niobium, advantageously tantalum and niobium.
• the nickel-based superalloy according to the invention comprises tantalum and/or niobium.
• the present invention further relates to the superalloy powder according to the invention.
• the superalloy according to the invention can be found in the form of a powder with a particle size of between 10 pm and 100 pm.
• the present invention further relates to a process for manufacturing a nickel-based superalloy powder according to the invention comprising the following steps:
• step C D- sieving of the powder obtained in step C), advantageously under an inert atmosphere, so as to obtain the targeted particle size
• the method can also present the following successive steps, after step E:
• F -containing the powder in particular a cylindrical container, more particularly under vacuum
• G - hot compaction of the filled container for example by Hot Uniaxial Compaction (CUC) in a press, or by Hot Isostatic Compaction (CIC - HIP in English), in particular in an autoclave;
• CRC Hot Uniaxial Compaction
• CIC - HIP Hot Isostatic Compaction
• I - peeling to remove the peripheral sheath corresponding to the walls of the initial container) and checks, in particular by ultrasound;
• the particle size of the powder is thus adapted according to the manufacturing technology of the parts based on superalloy powder envisaged.
• the particle size ranges used for the different manufacturing processes vary depending on the technology, equipment and targeted applications. In general, if we combine all the applications, the powder used for these processes will have more or less wide particle size distributions between 10 pm and 100 pm.
• the present invention further relates to a method of manufacturing a part, in particular turbines, in superalloy according to the invention or in superalloy powder according to the invention, characterized in that it comprises the following steps: a- forging , b- gradient heat treatment of the part obtained in step a), c- final heat treatment of the entire part with dual microstructure obtained in step b) d- recovery of the part obtained in step c).
• Step a) of forging can be carried out by methods well known to those skilled in the art, in particular on the sections obtained in step J. It can for example be a stamping (such as for example the isothermal forging). This technique is well known to those skilled in the art.
• This step a) makes it possible to obtain a superalloy part.
• Gradient heat treatment step b) can be implemented using the method and device described in patent application FR3043410.
• step b) of gradient heat treatment of the part obtained in step a) comprises: bl- a first heating of a zone of the part to a first temperature (Tl) greater than the solvus temperature of the prime gamma phase of said superalloy and lower than the melting temperature of said superalloy.
• It can thus include heating of a zone of the part (for example of the rim of the disc) to a first temperature (Tl) higher by at least 5 ° C than the solvus temperature of the gamma prime phase of said superalloy ( advantageously between +5 °C and +15 °C relative to the solvus temperature of the gamma prime phase of said superalloy) and lower than the melting temperature of said superalloy (it is therefore a supersolvus treatment that is - i.e. a supersolvus solution).
• the duration of this treatment can be between 1 hour and 8 hours.
• the gradient heat treatment can for example be carried out by local induction heating or by any method or device described in FR3043410.
• the zone of the part undergoing the first temperature (Tl) consists of the rim zone of the disk, the rest of the part not being impacted by this treatment.
• the supersolvus treatment (temperature Tl) makes it possible to use 100% of the hardening potential associated with the gamma prime phase to maintain hardening that is still effective at high temperatures (800 °C and even able to withstand peaks at 850 °C), while by increasing the grain size to improve the alloy's resistance to hot creep and crack propagation.
• the grain size is thus advantageously greater than or equal to 15 ⁇ m (measured by the intercept method).
• the grain size is advantageously 40 ⁇ m on average to maintain good fatigue resistance.
• Step b) therefore makes it possible to obtain a part with a dual or gradient microstructure, that is to say not having a homogeneous microstructure, in particular whose grain size is not the same, depending on whether we place our in the area of the part which has undergone the supersolvus treatment or that which has not been impacted by the supersolvus treatment.
• the area of the part having undergone the supersolvus treatment contains large grains and that which has not been impacted by the supersolvus treatment contains fine grains.
• the part with a dual or gradient microstructure according to the invention therefore contains large grains and fine grains, advantageously large grains having a size greater than or equal to 15 pm, in particular in the area of the part having undergone the supersolvus treatment, for example in the rim of the disc, and fine grains, in particular from forging, having a size less than 15 pm, in particular in the area of the part which has not been impacted by the supersolvus treatment, for example in the disc bore.
• Grain size is measured by the intercept method.
• Step c) of the process according to the invention may comprise the following successive steps: cl- putting the entire part obtained in step b) into solution at a temperature lower than the solvus temperature of the gamma phase prime of said superalloy (T2) (it is therefore a subsolvus treatment or subsolvus solution), for example at a temperature T2 between -80 °C and -20 °C relative to the solvus of the gamma prime phase ; c2- cooling or quenching of the entire part obtained in step cl); advantageously the cooling speed is adapted to the massiveness of the part in order to obtain an optimal size and distribution of the gamma prime hardening phase, more advantageously it is of the order of 100 °C/min (the speed can vary from 80 to 120 °C/min depending on the localisation).
• the final heat treatment of step c) is therefore the classic heat treatment of gamma/gamma prime alloys.
• the objective of this treatment is to treat the structure not impacted by the gradient treatment in order to have, in these zones, a final structure and therefore mechanical properties equivalent to the desired level.
• the grain size remains small, advantageously less than 10 pm (measured by the intercept method), which makes it possible to obtain good traction and fatigue properties at average temperatures, for example below 750°C.
• This second solution thus makes it possible to refine the size of the precipitates y' (gamma prime) throughout the part, while maintaining a fine grain size in the areas which did not undergo the first solution. .
• the part obtained thus has a grain size of 6-7 ASTM (28 - 40 pm) in the rim intended to be subjected to creep at very high temperatures, and a grain size of 10-12 ASTM (5 - 10 pm) in the rest of the part which is mainly stressed in traction and fatigue at lower temperatures.
• step cl) can be in the range 1 hour - 8 hours.
• step c3) may consist of one or more income treatments, advantageously two income treatments.
• This can be a single-tier or dual-tier income treatment.
• a relatively hot final tempering treatment for example in the range 730°C - 870°C, in particular 730°C-850°C, for example a first tempering at a temperature around 850°C, more particularly 850 °C, followed by a second tempering at a temperature between 730 °C and 800 °C, advantageously around 800 °C, in particular 800 °C, makes it possible to stabilize the microstructure of the part at high temperature. also makes it possible to relax the residual stresses resulting from the quenching associated with the treatment at temperature T2.
• the duration of step c3) can be in the range 2 hours - 24 hours (for example a first temper for a period of 4 hours - 8 hours, in particular at a temperature of 850 ° C, followed by a second heated for a period of 4 hours - 16 hours, in particular at a temperature of 800°C).
• tempering and quenching treatments are carried out using techniques well known to those skilled in the art.
• thermal tempering treatments can be carried out homogeneously over the entire part, but it is also possible to treat only part of the part in order to optimize the tempering according to the characteristics targeted in each zone. For example, only the area of the part having undergone the supersolvus treatment such as the rim of the disc can be treated at a tempering temperature around 850°C (advantageously 850°C) to precipitate the carbides. M 23 C 6 , before treating the entire part at a temperature between 730 °C and 800 °C to stabilize the precipitation / (gamma prime) in the bore of the part.
• the present invention finally relates to a part made of superalloy according to the present invention or of superalloy powder according to the present invention, having a dual microstructure, advantageously capable of being obtained by the process according to the present invention.
• a turbomachine part more advantageously a turbine part, in particular a turbine disk, a compressor disk, a ring, a flange, or a turbine casing, more particularly of a turbine disk, for example of aircraft and/or helicopter engines.
• the part according to the invention therefore has a dual or gradient microstructure, that is to say it does not have a homogeneous microstructure.
• the grain size of the part is not the same depending on the area of the part. It therefore contains large grains and fine grains, advantageously large grains having a size greater than or equal to 15 ⁇ m, advantageously 40 ⁇ m on average, and fine grains having a size less than 15 ⁇ m.
• one area of the part contains large grains and the rest of the part and/or another area of the part contains fine grains.
• the rim zone of the disk is coarse-grained, advantageously having grains having a size greater than or equal to 15 pm, advantageously 40 pm on average, and the zone of the bore of the disc is fine-grained, advantageously having grains having a size less than 3 p.m. Grain size is measured by the intercept method.
• the coarse-grained zone of the part has good creep resistance according to standard NF EN ISO 204 August 2009 at a temperature of 850°C, more advantageously a duration greater than 37 hours, at 0.2% elongation under a stress of 200 MPa and a temperature of 850 °C.
• the fine-grained zone of the part has good tensile strength according to Standard NF EN 2002-001/06 at a temperature below 750°C, in particular an elastic limit at 20°C greater than 1100 MPa .
• Figure 1 represents the diagram of a forged disc having a gradient microstructure, with large grains of 28 - 40 pm in the rim and small grains of 5 - 10 pm in the rest of the part.
• the transition zone between the two microstructures is shown schematically by dotted lines.
• Nickel-based superalloys according to the invention (examples 1 to 8 and 10 to 17) were manufactured according to the following process: vacuum casting of an ingot, then atomization under argon of this ingot, sieving at 53 pm, placing containerized powders with degassing, then hot spinning of these powders in bar form.
• the nickel-based superalloy of Example 9 was produced by VIM casting, according to a process well known to those skilled in the art.
• the alloys manufactured according to the invention have the chemical composition in % by weight indicated in Table 1 above.
• the 5 comparative superalloys have the composition indicated in Table 2 below.
• the calculated solvus/(gamma prime) and solidus temperatures for the different alloys and the solidus-solvus/(gamma prime) gap are shown in Table 3 below.
• the density estimated using a modified version of Hull's formula as shown above is also shown in Table 3.
• the value of the formulas Al + Ti + Nb + Ta in at% and Al / (Ti + Nb + Ta) in % at is also shown in Table 3.
• a part of the bar then underwent treatment at a temperature between 1180 °C and 1200 °C for a duration of 2 h (supersolvus treatment) then cooling at around 30 °C/min.
• the entire bar then underwent treatment at a temperature between 1145 °C and 1165 °C for a duration of 2 h (subsolvus treatment) followed by quenching at a speed of 100 °C/min and tempering at a temperature of 850°C for one duration of 4 hours to 8 hours followed by a second tempering at a temperature of 800°C for a period of 4 hours to 16 hours.
• the amount of M23C6 carbides calculated using the CALPHAD (CALculation of PHAse Diagrams) method is shown in Table 3.
• the solvus temperature of M 2 3C 6 carbides is also shown in Table 3.
• the advantages obtained by this invention are twofold: the first advantage is facilitated industrial implementation thanks to the widening of the grain coarsening heat treatment window which goes from 10 °C to 20 °C or more, and the second advantage is an increase in the lifespan of parts at very high temperatures (850 °C ).
• the alloys according to the invention have an improvement in creep resistance at 850°C to increase the lifespan of the part with respect to creep. At this temperature, grain boundaries are considered the weak points of the microstructure. This is why we use grain size enlargement to reduce the density of grain boundaries and thus limit their impact.
• this coarsening is also associated with a precipitation of M23C6 carbides in the grain boundaries.
• These carbides are intended to reinforce grain boundaries in order to limit creep-diffusion mechanisms and slow down metal deformation by creep, and thus allow parts to operate longer at 850°C.

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