The present invention relates to the general field of nickel-based superalloys for turbomachines, in particular for fixed blades, also called distributors or rectifiers, or mobile blades, or even ring segments.

Prior art

Nickel-based superalloys are generally used for the hot parts of turbomachines, that is, the parts of turbomachines located downstream of the combustion chamber.

The main advantages of nickel-based superalloys are that they combine high creep resistance at temperatures between 650 ° C and 1200 ° C, as well as resistance to oxidation and corrosion.

The high temperature resistance is mainly due to the microstructure of these materials, which is composed of a face-centered cubic crystal structure (CFC) g-Ni matrix and ordered hardening precipitates y'-Ni3AI of structure L12.

In order to improve the resistance of the superalloy part to a corrosive and / or oxidizing environment, such as combustion gases, for example, a protective coating can be deposited on the part.

The protective coating can also have a thermal insulating role to reduce the temperature seen by the superalloy substrate on which the protective coating is deposited.

The protective coating usually consists of a first layer, and a second layer deposited on the first layer.

The first layer, generally called the tie layer or underlayer, is deposited on the superalloy. The first layer is commonly made of an aluminoforming alloy.

The second layer, generally referred to as a thermal barrier, is a porous ceramic coating.

However, at high temperatures, an important microscopic scale inter-diffusion phenomenon takes place between the first layer and the superalloy, thus modifying their respective chemical compositions. Chemical modification of the superalloy and the first layer changes their properties, thereby influencing the adhesion of the protective coating.

Furthermore, during the manufacture of the part in superalloy, parasitic grains of the “Freckle” type may form. These parasitic grains are liable to cause the part to break prematurely.

Disclosure of the invention

The object of the present invention is to provide compositions of nickel-based superalloys which make it possible to improve the adhesion between the superalloy and the protective coating.

Another object of the present invention is to provide compositions of nickel-based superalloys which make it possible to improve the mechanical characteristics, and in particular the resistance to creep.

Another object of the present invention is to provide superalloy compositions which has good resistance to the environment, and in particular corrosion resistance and oxidation resistance.

It is also an object of the present invention to provide superalloy compositions which have a reduced density.

According to a first aspect, the invention provides a nickel-based superalloy comprising, in weight percentages, 4 to 6% aluminum, 5 to 8% cobalt, 6 to 9% chromium, 0.1 to 0.9. % hafnium, 2 to 4% molybdenum, 5 to 7% rhenium, 5 to 7% tantalum, 2 to 5% tungsten, 0 to 0.1% silicon, the remainder being nickel and impurities inevitable.

The term “nickel-based alloy” is defined as an alloy in which the percentage by mass of nickel is predominant.

Unavoidable impurities are defined as those elements which are not intentionally added to the composition and which are supplied with other elements. Among the inevitable impurities, mention may in particular be made of carbon (C) and sulfur (S).

The nickel-based superalloy according to the invention has good microstructural stability in temperature, thus making it possible to obtain high mechanical characteristics in temperature.

The nickel-based superalloy according to the invention makes it possible to improve the resistance of a protective coating on said superalloy thanks to the absence of titanium (Ti).

The nickel-based superalloy according to the invention has high resistance to corrosion and oxidation.

The nickel-based superalloy according to the invention reduces the susceptibility to foundry defect formation.

The nickel-based superalloy according to the invention provides a density of less than 8.9 g. cm 3.

According to one possible variant, the superalloy may comprise, in percentages by weight, 4.5 to 5.5% aluminum, 5 to 8% cobalt, 6.5 to 8.5% chromium, 0.1 to 0, 6% hafnium, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 4.5% tungsten, 0 0.1% silicon, the remainder being nickel and inevitable impurities.

Furthermore, the superalloy may comprise, in percentages by mass, 4.5 to 5.5% of aluminum, 5 to 8% cobalt, 6.5 to 8.5% chromium, 0.1 to 0.6% hafnium, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 6.5% tantalum, 2.5 to 4.5% tungsten, the remainder being nickel and inevitable impurities.

In this variant, silicon is an inevitable impurity.

The superalloy can also comprise, in percentages by mass, 4.5 to 5.5% aluminum, 5 to 8% cobalt, 6.5 to 8.5% chromium, 0.2 to 0.5% hafnium , 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 4.5% tungsten, the remainder being nickel and inevitable impurities.

According to one possible variant, the superalloy may comprise, in weight percentages, 4.5 to 5.5% aluminum, 6 to 8% cobalt, 6.5 to 7.5% chromium, 0.1 to 0, 6% hafnium, and preferably 0.2 to 0.5%, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 3.5 to 4.5% tungsten, the remainder being nickel and inevitable impurities.

According to one possible variant, the superalloy can also comprise, in percentages by mass, 4.5 to 5.5% aluminum, 6 to 8% cobalt, 6.5 to 7.5% chromium, 0.1 to 0 , 6% hafnium, and preferably 0.2 to 0.5%, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum , 2.5 to 3.5% tungsten, the remainder being nickel and inevitable impurities.

The superalloy may further comprise, in percentages by weight, 4.5 to 5.5% aluminum, 5 to 7% cobalt, 6.5 to 7.5% chromium, 0.1 to 0.6% of hafnium, and preferably 0.2 to 0.5%, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 3.5% tungsten, the remainder being nickel and inevitable impurities.

According to one possible variant, the superalloy may comprise, in percentages by weight, 4.5 to 5.5% aluminum, 6 to 8% cobalt, 7.5 to 8.5% chromium, 0.1 to 0, 6% hafnium, and preferably 0.2 to 0.5%, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 3.5% tungsten, the remainder being nickel and inevitable impurities.

According to a second aspect, the invention provides a nickel-based superalloy turbomachine part according to any one of the preceding characteristics.

The part may be an element of an aircraft turbomachine turbine, for example a high-pressure turbine or a low-pressure turbine, or else a compressor element, and in particular a high-pressure compressor.

According to an additional characteristic, the turbine or compressor part may be a blade, said blade possibly being a moving blade or a fixed blade, or else a ring sector.

According to another characteristic, the turbomachine part comprises a thermal protective coating formed of a bonding layer deposited on the nickel-based superalloy, and a thermal barrier layer deposited on the bonding layer.

According to another characteristic, the turbomachine part is monocrystalline, preferably with a crystalline structure oriented in a crystallographic direction <001>.

According to a third aspect, the invention provides a method of manufacturing a nickel-based superalloy turbomachine part according to any one of the preceding characteristics by foundry.

According to an additional characteristic, the method comprises the deposition of a thermal protective coating on the part in nickel-based superalloy according to the following steps:

depositing a tie layer on the part;

deposition of a thermal barrier layer on the tie layer.

Description of the embodiments

The superalloy according to the invention comprises a nickel base with which major addition elements are associated.

Major addition elements include: cobalt Co, chromium Cr, molybdenum Mo, tungsten W, aluminum Al, tantalum Ta, titanium Ti, and rhenium Re.

The superalloy can also include minor addition elements, which are addition elements whose maximum percentage in the superalloy does not exceed 1% by weight percent.

Minor addition elements include: hafnium Hf and silicon Si.

The nickel-based superalloy comprises, in percentages by mass, 4 to 6% aluminum, 5 to 8% cobalt, 6 to 9% chromium, 0.1 to 0.9% hafnium, 2 to 4% of molybdenum, 5 to 7% rhenium, 5 to 7% tantalum, 2 to 5% tungsten, 0 to 0.1% silicon, the remainder being nickel and inevitable impurities.

The nickel-based superalloy can also advantageously comprise, in percentages by weight, 4 to 6% aluminum, 5 to 8% cobalt, 6 to 9% chromium, 0.1 to 0.9% hafnium, 2-4% molybdenum, 5-7% rhenium, 5-7% tantalum, 2-5% tungsten, the remainder being nickel and inevitable impurities. In this variant, silicon is an inevitable impurity.

The nickel-based superalloy can also comprise avantageuse, in percentages by mass, 4.5 to 5.5% aluminum, 5 to 8% cobalt, 6.5 to 8.5% chromium, 0.1 to 0.6% hafnium, 2.5 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 4.5% tungsten, 0 to 0.1% silicon, the remainder being made up of nickel and inevitable impurities.

The nickel-based superalloy can also advantageously comprise, in percentages by mass, 4.5 to 5.5% aluminum, 5 to 8% cobalt, 6.5 to 8.5% chromium, 0.1 0.6% hafnium, 2.5-3.5% molybdenum, 5.5-6.5% rhenium, 5.5-6.5% tantalum, 2.5-4.5% tungsten, the remainder being nickel and inevitable impurities. In this variant, silicon is an inevitable impurity.

The nickel-based superalloy can also advantageously comprise, in percentages by mass, 4.5 to 5.5% aluminum, 5 to 8% cobalt, 6.5 to 8.5% chromium, 0.2 0.5% hafnium, 2.5-3.5% molybdenum, 5.5-6.5% rhenium, 5.5-6.5% tantalum, 2.5-4.5% tungsten, the remainder being nickel and inevitable impurities.

The superalloy can also advantageously comprise, in percentages by mass, 4.5 to 5.5% aluminum, 6 to 8% cobalt, 6.5 to 7.5% chromium, 0.1 to 0, 6% hafnium (and preferably 0.2 to 0.5%), 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum , 3.5 to 4.5% tungsten, the remainder being nickel and inevitable impurities.

Advantageously, the superalloy can comprise, in weight percentages, 4.5 to 5.5% aluminum, 6 to 8% cobalt, 6.5 to 7.5% chromium, 0.1 to 0.6 % hafnium (and preferably 0.2 to 0.5%), 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 3.5% tungsten, the remainder being nickel and inevitable impurities.

The superalloy can also advantageously comprise, in percentages by mass, 4.5 to 5.5% aluminum, 5 to 7% cobalt, 6.5 to 7.5% chromium, 0.1 to 0, 6% hafnium (and preferably 0.2 to 0.5%), 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum , 2.5 to 3.5% tungsten, the remainder being nickel and inevitable impurities.

Preferably, the superalloy may comprise, in percentages by weight, 4.5 to 5.5% aluminum, 6 to 8% cobalt, 7.5 to 8.5% chromium, 0.1 to 0.6 % hafnium (and preferably 0.2 to 0.5%), 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 3.5% tungsten, the remainder being nickel and inevitable impurities.

Cobalt, chromium, tungsten, molybdenum and rhenium participate mainly in the hardening of phase g, the austenitic matrix of CFC structure.

Aluminum and tantalum promote precipitation of the y ’phase, the hardening phase Ni3 (Al, Ti, Ta) of ordered cubic structure L12.

In addition, rhenium slows down diffusive processes, limits the coalescence of the g ’phase, thus improving creep resistance at high temperature. However, the rhenium content should not be too high so as not to negatively impact the other mechanical properties of the superalloy part.

Claims

[Claim 1] Nickel-based superalloy comprising, in weight percentages, 4 to 6% aluminum, 5 to 8% cobalt, 6 to 9% chromium, 0.1 to 0.9% hafnium, 2 to 4 % molybdenum, 5-7% rhenium, 5-7% tantalum, 2-5% tungsten, 0-0.1% silicon, the remainder being nickel and inevitable impurities.

[Claim 2] A superalloy according to claim 1, wherein said superalloy comprises, in weight percentages, 4.5 to 5.5% aluminum, 5 to 8% cobalt, 6.5 to 8.5% chromium, 0.1 to 0.6% hafnium, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 4, 5% tungsten, 0 to 0.1% silicon, the remainder being nickel and inevitable impurities.

[Claim 3] A superalloy according to claim 2, wherein said superalloy comprises, in weight percentages, 4.5 to 5.5% aluminum, 5 to 8% cobalt, 6.5 to 8.5% chromium, 0.1 to 0.6% hafnium, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 4, 5% tungsten, the remainder being nickel and inevitable impurities.

[Claim 4] A superalloy according to claim 3, wherein said superalloy comprises, in weight percentages, 4.5 to 5.5% aluminum, 5 to 8% cobalt, 6.5 to 8.5% chromium, 0.2 to 0.5% hafnium, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 4, 5% tungsten, the remainder being nickel and inevitable impurities.

[Claim 5] A superalloy according to claim 3, wherein said superalloy comprises, in weight percentages, 4.5 to 5.5% aluminum, 6 to 8% cobalt, 6.5 to 7.5% chromium, 0.1 to 0.6% hafnium, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 3.5 to 4, 5% tungsten, the remainder being nickel and inevitable impurities.

[Claim 6] A superalloy according to claim 3, wherein said superalloy comprises, in weight percentages, 4.5 to 5.5% aluminum, 6 to 8% cobalt, 6.5 to 7.5% chromium, 0.1 to 0.6% hafnium, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 3, 5% tungsten, the remainder being nickel and inevitable impurities.

[Claim 7] A superalloy according to claim 3, wherein said superalloy comprises, in weight percentages, 4.5 to 5.5% aluminum, 5 to 7% cobalt, 6.5 to 7.5% chromium, 0.1 to 0.6% hafnium, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 3, 5% tungsten, the remainder being nickel and inevitable impurities.

[Claim 8] A superalloy according to claim 3, wherein said superalloy comprises, in weight percentages, 4.5 to 5.5% aluminum, 6 to 8% cobalt, 7.5 to 8.5% chromium, 0.1 to 0.6% hafnium, 2.5 to 3.5% molybdenum, 5.5 to 6.5% rhenium, 5.5 to 6.5% tantalum, 2.5 to 3, 5% tungsten, the remainder being nickel and inevitable impurities.

[Claim 9] A nickel-based superalloy turbomachine part according to any one of claims 1 to 8.

[Claim 10] The part of claim 9, wherein said part comprises a thermal protective coating formed of a tie layer deposited on the nickel-based superalloy, and a thermal barrier layer deposited on the tie layer.

[Claim 11] A part according to claim 9 or claim 10, wherein said part is single crystal.

[Claim 12] A method of manufacturing a nickel-based superalloy turbomachine part according to any one of claims 1 to 11 by foundry.

[Claim 13] The method of claim 12, wherein the method comprises depositing a thermal protective coating on the nickel-based superalloy part according to the following steps: depositing a tie layer on the part; deposition of a thermal barrier layer on the tie layer.