Nickel-cobalt type material and manufacturing process

Abstract

A nickel-cobalt type material (100) and a manufacturing process comprise the formation of a doped nickel-cobalt precursor material (130) by means of an electrodeposition process. The process also comprises heat treatment of the doped nickel-cobalt precursor material (130), wherein the heat treatment comprises at least heating within a temperature range below the starting temperature of grain growth in the doped nickel-cobalt precursor material (130). Figure for the abstract: Fig 5

Description

Title of the invention: Nickel-cobalt type material and manufacturing process technical field

[0001] The present invention relates generally to a material and a method for manufacturing a material, in particular a nickel-cobalt type material. Background

[0002] We seek to design materials that can be used in applications involving polycyclic and oligocyclic fatigue. For example, components for engine or turbine engine environments, or other environments in the aviation or aerospace field, may require such materials. Summary description

[0003] In one aspect, the present invention relates to a method for manufacturing a material. This method may include the formation of a doped nickel-cobalt type precursor material and the heat treatment of the doped nickel-cobalt type precursor material, the heat treatment comprising at least heating to a temperature lower than the starting temperature of grain growth in the doped nickel-cobalt type precursor material to form a heat-treated nickel-cobalt type material. Brief description of the drawings

[0004] In the drawings:

[0005] [Fig-1] is a schematic perspective view of a gas turbine engine comprising an example component, comprising a nickel-cobalt type material according to various aspects described herein;

[0006] [Fig.2] is a schematic representation of a nickel-cobalt type material given as an example, which can be used in the component of [Fig.1];

[0007] [Fig.3] is a schematic representation of an electroforming bath for forming a precursor material of the nickel-cobalt type material of [Fig.2];

[0008] [Fig.4] is a phase diagram of the nickel-cobalt type material of [Fig.2] including an example of starting temperature for grain growth during the formation of the nickel-cobalt type material.

[0009] [Fig.5] is a schematic representation of the precursor material of [Fig.3];

[0010] [Fig.6] is a schematic representation of the precursor material of [Fig.5] after a heat treatment to form the nickel-cobalt type material of [Fig.2];

[0011] [Fig.7] is an example of a stress-strain curve diagram that compares in general an ultrafine twinned nanocrystalline nickel-cobalt grain to a nanocrystalline grain of the nickel-cobalt type material of [Fig.2];

[0012] [Fig.8] is a graph establishing a relationship between the stacking defect energy and the percentage of cobalt in the nickel-cobalt type material of [Fig.2];

[0013] [Fig.9] is a graph illustrating fatigue resistance as a function of size grains for an example of metal in the form of stainless steel;

[0014] [Fig. 10] is a graph illustrating fatigue strength as a function of grain size for another example of metal in the form of galvanically deposited nickel. Detailed description

[0015] Aircraft engines, and in particular the fluid distribution systems they contain, operate in an aggressive environment subjected to both low-cycle fatigue (LCF) and high-cycle fatigue (HCF). Current aircraft engine designs with standard coarse-grained annealed steel and tubing of standard wall thicknesses are oversized for a highly localized worst-case stress condition. Regions subjected to low stresses have the same uniform wall thickness and are generally oversized.In general, although an additional electroforming process is customizable, there is currently no addition of material only where needed - a high-performance material deposited galvanically, exhibiting high fatigue resistance, high temperature stability, and high mechanical strength and endurance.

[0016] Aspects of the present invention relate to reducing the initiation and propagation of fatigue cracks, as well as fracture, in nickel-cobalt type materials. Aspects of the present invention relate to novel galvanically deposited nickel-based nanocrystalline alloys exhibiting excellent thermal stability, high resistance to low-cycle fatigue, and crack-resistant material performance under high-cycle fatigue. This results in efficient material utilization via the electrodeposition process for a wide range of applications, including the manufacture of turbine engine components.

[0017] The relationship between strength and grain size is associated with the interactions between dislocations and grain boundaries. Under the application of stress, dislocations existing within a crystal lattice or created by plastic deformation can propagate along slip planes traversing the crystal lattice and along grain boundaries. Dislocations tend to accumulate at grain boundaries because the grain boundaries provide a repulsive stress that opposes the Prolonged dislocation propagation. When the repulsive stress of a grain boundary exceeds the propagation force of dislocations, the dislocations are unable to cross the grain boundary. As dislocations accumulate, their collective propagation force increases. In this way, dislocations can cross the grain boundary when their propagation force exceeds the repulsive stress of the grain boundary.

[0018] Reducing grain size also reduces the space available for the potential accumulation of dislocations at the grain boundary, thereby increasing the applied stress required for a dislocation to propagate across the grain boundary. The greater the applied stress required to move the dislocation, the greater the yield strength. There is therefore an inverse relationship between grain size and mechanical strength, which can be described by the Hall-Petch equation shown in (1) below:

[0019]

[0020] where o is the strength and a is the grain size. Thus, the strength of a material generally increases as the grain size decreases according to the Hall-Petch relationship. Since this relationship is asymptotic, the strength of the material generally increases as the grain size decreases up to a certain minimum value, below which the Hall-Petch relationship no longer applies. There is therefore a limit to the increase in strength that can be achieved by reducing the grain size alone.

[0021] The nickel-cobalt-type materials disclosed herein and the components made from them can provide improved fatigue resistance, endurance, and thermal stability. The improved fatigue resistance can be attributed at least in part to a phosphorus dopant, the cobalt content in the nickel-cobalt alloy, or heat treatment of the precursor material. Generally, each of these aspects can at least partially contribute to the fatigue resistance, tensile strength, and thermal stability of the phosphorus-doped nickel-cobalt alloys and components disclosed herein. Furthermore, aspects of the invention that utilize phosphorus, for example, for stabilization or anchoring, can be replaced by other similar alloying elements, such as boron or manganese, which are non-limiting examples.Furthermore, the materials disclosed here may also include other alloys such as nickel-phosphorus, nickel-cobalt-manganese, nickel-boron or cobalt-phosphorus alloys, which are non-limiting examples.

[0022] For the purpose of illustration, aspects of the invention will be described in the In the context of a gas turbine engine component, gas turbine engines are used for land and water transportation, as well as for electricity generation, and are also commonly used in aeronautical applications such as airplanes and helicopters. It is understood, however, that the invention is not limited to these examples and may have general applications outside the aeronautical field, such as other mobile or fixed applications in industry, commerce, and housing.

[0023] The term "a set" used herein may include any number of the elements respectively described, including a single element. Furthermore, the term "level with" a given surface means being at the same level as, or tangential to, that surface. Moreover, all directional references (e.g., radial, axial, proximal, distal, superior, inferior, up, down, left, right, lateral, front, rear, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, rear, etc.) are used solely for identification purposes to facilitate understanding of this description and do not create any limitations, particularly with respect to the position, orientation, or use of the present invention.Connection references (e.g., fixed, coupled, connected, and linked) should be interpreted broadly and may include intermediate elements between a group of elements and relative movement between elements, unless otherwise specified. Therefore, connection references do not necessarily imply that two elements are directly connected and in a fixed relationship to each other. The drawings provided as examples are for illustrative purposes only, and the dimensions, positions, orders, and relative sizes appearing in the accompanying drawings may vary.

[0024] An example of a turbine engine 10 is shown in [Fig. 1]. The turbine engine 10 may be a gas turbine engine, including a turbofan, turboprop, or turboshaft engine, these examples being non-limiting. The turbine engine 10 comprises, in downstream series flow relationship, a fan section 18 including a fan 20, a compressor section 22 including a low-pressure (LP) pre-compressor or compressor 24 and a high-pressure (HP) compressor 26, a combustion section 28 including a combustion device 30, a turbine section 32 including an HP turbine 34 and an LP turbine 36, and an exhaust section 38.

[0025] The blower section 18 comprises a blower housing 40 which surrounds the blower 20. The blower 20 comprises a plurality of radially arranged blower blades 42. The HP compressor 26, the combustion device 30, and the HP turbine 34 form a core 44 of the engine 10, which generates combustion gases. The core 44 is surrounded by a core casing 46 which can be coupled to the blower casing 40. The compressor section 22 supplies high-pressure air to the combustion device 30. The high-pressure air is mixed with fuel and burned in the combustion device 30. The hot, compressed combustion gases pass through the HP turbine 34 and the LP turbine 36 before being ejected from the turbine engine 10.

[0026] As the compressed gases pass through the compressor section 22, the turbines 34 and 36 extract rotational energy from the gas flow passing through the turbine engine 10. The HP turbine 34 can be coupled to a compression mechanism (not shown) of the compressor section 22 by means of a shaft to drive the compression mechanism. The LP turbine 36 can be coupled to the blower 20 by means of a shaft to drive the blower 20.Optionally, the turbine engine 10 can also have an afterburner device which burns an additional amount of fuel downstream of the turbine section 32 to increase the velocity of the ejected gases, thereby increasing thrust.

[0027] The components of the turbine engine 10 may be subjected to high temperatures and stresses, including low-cycle and high-cycle fatigue, as well as other disturbances that may occur during operation. Non-limiting examples of such components include rotating or stationary blades in the compressor section 22 or turbine section 32, or components included in or coupled to the core casing 46, such as supports, plates, or seals. These components may include materials designed for the strength, resilience, or temperature requirements of the surrounding environment, including metal alloys.

[0028] It has been determined that a galvanically deposited nanocrystalline nickel-cobalt-phosphorus material has specific microstructural characteristics that increase fatigue resistance. These properties significantly improve crack initiation resistance and increase fracture toughness. Figure 2 shows an example of a heat-treated nickel-cobalt material or alloy, herein referred to as nickel-cobalt material 100, which can be used in a component of the turbine engine 10 (Fig. 1) or a part thereof. The example of nickel-cobalt material 100 is represented with untwinned nanocrystalline nickel-cobalt grains, which are referred to here as untwinned grains 101, as well as twinned nanocrystalline nickel-cobalt grains, which are referred to as twinned grains 102. The untwinned grains 101 or the twinned grains 102 can be distributed homogeneously or heterogeneously in the nickel-cobalt material 100.Structures or grains of other sizes, beyond those shown in [Fig.2], including amorphous metal structures or twinned or untwinned grains of any suitable size such as microcrystalline grains or coarse grains, can be used in the nickel-cobalt material. 100; however, it has been determined that nanocrystalline grain sizes provide an additional benefit for fatigue resistance.

[0029] The grains 101, 102 may have an average grain size 104 which is in a nanocrystalline region. The expression "nanocrystalline region" may refer, for example, to a region having grain sizes located on a nanometric scale, such as less than 100 nm, in a non-limiting example.

[0030] Grain boundaries 106 are defined along adjacent grains 101, 102, and triple junction microvoids 108 are defined at the junction of three adjacent grains 101, 102, as shown. The twinned grains 102 are illustrated with a first twin 111, shown in a darker shade for clarity, and a second twin 112.

[0031] Precipitates, represented as phosphorus 120 precipitates, may also be included in the nickel-cobalt material 100. The phosphorus 120 precipitates are shown at the grain boundaries 106. Although not shown for clarity, the phosphorus precipitates may also be dispersed in the grains 101, 102 (e.g., in the grain lattice) as well as in the grain boundaries 106. The phosphorus 120 precipitates can provide Zener anchorage that prevents further grain growth by means of an anchoring force that resists the movement of dislocations or the passage through other grain boundaries. The phosphorus 120 precipitates or intragranular twinning in any or all of the grains 101, 102 can provide increased endurance or fatigue resistance.It is also envisaged that precipitates or other alloying materials, including boron or manganese, may be used instead of, or in addition to, phosphorus 120 precipitates.

[0032] The nickel-cobalt 100 material example may comprise approximately 30% to 35% by atomic mass of cobalt, approximately 1,000 ppm to 3,500 ppm by atomic mass of phosphorus, and nickel as a complement to the material. It is also envisaged that other ranges or proportions of nickel, cobalt, or phosphorus may be used. In other non-limiting examples, the nickel concentration in the nickel-cobalt 100 material may be approximately 60% to 80% by atomic mass. The cobalt concentration in the nickel-cobalt 100 material may be approximately 20% to 50%. The phosphorus concentration in the nickel-cobalt 100 material may be approximately 500 ppm to 2,000 ppm by atomic mass.

[0033] Figure 3 shows that the example nickel-cobalt material 100 can be formed by producing a doped nickel-cobalt precursor material, referred to herein as precursor material 130, using a galvanic deposition process, or "electrodeposition". Precursor material 130 can be formed using Any suitable electrodeposition process, such as a Watts bath, can be used. The electrodeposition process can be carried out using an electrodeposition bath 140 containing a nickel source 142 and a cobalt source 144. Optionally, a phosphorus source (not shown) can be added, either to the electrodeposition bath 140 or separately as a liquid solution. The electrodeposition bath 140 may further include boric acid or a salt thereof to prevent electrode surface passivation or nickel reduction and to act as a surfactant; one or more chelating or complexing agents to chelate or combine with particular ions in the electrodeposition bath; or a saccharin inhibitor to control grain size. In addition, the electrodeposition bath may include one or more surfactants to reduce the tendency to cavitation.The electrodeposition bath may also include various other additives at concentrations of less than 1% by weight, including buffering agents, wetting agents, grain refining products, thinning agents, etc.

[0034] The nickel source 142 for the electrodeposition bath 140 may comprise nickel sulfate, nickel hypophosphite, nickel oxide, nickel carbonate, or nickel chloride, as well as combinations thereof. Preferably, the nickel source 142 comprises nickel sulfate. The nickel source 142 may be supplied with an ionic concentration of approximately 50 mM to approximately 1 M, for example, from approximately 250 mM to approximately 750 mM.

[0035] The cobalt source 144 for the electrodeposition bath 140 may comprise cobalt sulfate, cobalt chloride, or cobalt carbonate, as well as combinations thereof. Preferably, the cobalt source 144 comprises cobalt sulfate. The cobalt source may be supplied with an ionic concentration of approximately 10 mM to approximately 100 mM, for example, from approximately 25 mM to approximately 75 mM.

[0036] The phosphorus source 146 for the electrodeposition bath 140 may comprise hypophosphorous acid or a hypophosphite-type salt. Examples of hypophosphite-type salts include sodium hypophosphite, potassium hypophosphite, nickel hypophosphite, or ammonium hypophosphite, or other hypophosphites of alkalis or alkaline earth metals, and combinations thereof. Preferably, the phosphorus source 146 comprises sodium hypophosphite. The phosphorus source 146 may be supplied with an ionic concentration of approximately 50 mM to approximately 500 mM, for example, from approximately 100 mM to approximately 250 mM.

[0037] One or more chelating agents 148 or complexing agents 150 may be added to the electrodeposition bath. Examples of chelating agents 148 include malonic acid, oxalic acid, succinic acid, citric acid, malic acid, maleic acid, tartaric acid, ethylenediamine, ethyl- Nediamine tetraacetic acid (EDTA), triethylenetetramine, diethylenetriamine, hydrazobenzene, amino acids, and salts of any of the preceding elements. Examples of complexing agents include acetic acid, propionic acid, glycolic acid, formic acid, lactic acid, glycine, and salts of any of the preceding elements. Salts of chelating or complexing agents may include alkalis or salts of alkaline earth metals, ammonium salts, nickel salts, and cobalt salts. Preferably, the electrodeposition bath 140 comprises at least one chelating agent 148 and at least one complexing agent 150. One or more chelating agents 148 may be supplied with a concentration of about 10 mM to about 250 mM, for example about 25 mM to about 200 mM.One or more complexing agents may be supplied with a concentration of approximately 100 mM to approximately 750 mM, for example, from approximately 250 mM to approximately 500 mM. Examples of surfactants for the electrodeposition bath include octylphenol ethoxylates (e.g., Triton X-100, etc.), octylphenoxy-polyethoxyethanol (e.g., IGEPALMD CA-360, etc.), sodium dodecyl sulfate (SDS), etc. One or more surfactants may be supplied with a concentration of approximately 10 to approximately 1000 ppm by weight.

[0038] A bath solution 152 can be prepared by combining the various components in an aqueous trainer. Generally, the bath solution 152 can be maintained at an acidic pH of approximately 3.3 to 4.3, for example, 3.5 to 4.0, using a suitable acidic agent (e.g., hypophosphorous acid, orthophosphoric acid, or sulfuric acid) and a suitable basic agent (e.g., sodium hydroxide). The electrodeposition bath 140 includes one or more anodes 154, such as the nickel source 142, the cobalt source 144, or the phosphorus source 146, which can release ions into the electrodeposition bath. The electrodeposition bath 140 may also include one or more cathodes 156. The cathodes 156 may act as a mandrel 157 that defines a shape for the precursor material 130 deposited on it. The mandrel 157 may have an oxide layer that allows for easy separation of the precursor material 130 from it.

[0039] The electrodeposition process can be carried out with a bath temperature below approximately 60 °C, for example, from approximately 40 to 55 °C. A wide range of current densities can be used, including a modulating current density. The current density can, for example, be between approximately 5 and 500 mA / cm².

[0040] One or more parameters of the electrodeposition bath 140 can be varied to obtain a desired precursor crystalline structure that includes the deposition of nanocrystalline grain regions. For example, in certain aspects, one can use Pulsed current electrodeposition techniques allow for varying the nucleation rate and growth of existing grains, for example, by varying the peak current density, pulse duration, and pulse interruption time, or by reversing the pulses. Pulsed electrodeposition can be particularly advantageous because it can produce finer-grained structures than can be obtained with direct current electrodeposition. Other electrodeposition parameters allow for obtaining the desired precursor crystalline structure, for example, by providing a variable bath composition, variable stirring speed, variable pH, etc.

[0041] The electrodeposition conditions, including bath chemistry and pulse parameters, can be selected to provide a resulting precursor material, such as the doped nickel-cobalt precursor material 130, having a desired structure. In some aspects, the precursor material 130 may have a metallic structure comprising crystalline regions made up of nanocrystalline grain structures. Amorphous regions may optionally be added; in this case, the proportion of amorphous regions relative to crystalline regions in the precursor material 130 can be selected to obtain the desired thermal stabilization or strengthening following heat treatment.

[0042] In a non-limiting example, the electrodeposition process can provide the precursor material 130 substantially in the form of a phosphorus-doped nickel-cobalt material comprising a nanocrystalline granular material. The nanocrystalline granular material can have a grain size distribution of less than approximately 100 nm, for example, from approximately 50 nanometers to approximately 100 nanometers. As another example, the electrodeposition process can provide the precursor material 130 substantially in the form of a boron-doped nickel-cobalt nanocrystalline granular material having a grain size distribution of approximately 50 to 100 nanometers.

[0043] Once electrodeposition is complete, the precursor material 130 can be subjected to heat treatment using any desired heat treatment system, including, for example, a batch furnace or a continuous furnace. Such a precursor material, when subjected to heat treatment as described herein, can exhibit high fatigue strength, ductility, or tensile strength.

[0044] It is envisaged that a controlled atmosphere may be provided. The controlled atmosphere may supply one or more gases to the heat treatment system, optionally under a negative pressure environment. For example, one or more gases may include hydrogen, nitrogen, argon, ammonia, carbon dioxide, carbon monoxide, helium, hydrocarbons (e.g., methane, ethane, propane, butane, etc.), or water vapor, as well as other gases. combinations of these. These gases can provide an endothermic or exothermic atmosphere. The specific heat treatment time and temperature program will depend on the composition of the precursor material 130 and the desired resulting properties following the heat treatment.

[0045] It is envisaged that the precursor material 130 can be subjected to a heat treatment for precipitate strengthening. Figure 4 shows a phase diagram 160 for the nickel-cobalt material 100 with superimposed examples of heat treatment zones for the heat treatment for precipitate strengthening.

[0046] The heat treatment can be carried out at a temperature, or within a temperature range, below the grain growth starting temperature to provide a precipitate strengthening heat treatment. The grain growth starting temperature in the precursor material can be determined by performing an isochronous heat treatment test on the precursor material. In the example shown, a phosphorus-doped nickel-cobalt alloy containing 30% cobalt can have a reference starting temperature Tstart of approximately 700 K. It should be noted, however, that the grain growth starting temperature can vary depending on the composition of the precursor material. The precipitate strengthening heat treatment produces phosphorus-120 precipitates that can cause Zener anchoring. The precipitate strengthening heat treatment can be carried out at a constant temperature.Alternatively, the temperature can vary, for example according to a heat treatment cycle that includes a sequence of heat treatment temperatures. Optionally, the material resulting from the first heat treatment to strengthen the precipitates can be quenched or slowly cooled.

[0047] In other non-limiting examples, the heat treatment for strengthening precipitates may include heat treatment in a temperature range from approximately 600 K to approximately 750 K, for example, from 630 K to 700 K in a non-limiting example. In other non-limiting examples, the heat treatment for strengthening precipitates may be carried out in a temperature range according to a heat treatment cycle that includes one or more temperature increases up to the starting temperature for grain growth over a time interval.For example, with a starting temperature of 700 K, an example of heat treatment for strengthening precipitates may include a heat treatment according to a cycle in a temperature range of about 630 K to about 700 K, with a first part of the cycle carried out in a temperature range of about 630 K to about 670 K, and a second part of the cycle carried out in a temperature range of about 670 K to about 700 K.

[0048] The shear force level sufficient to form intragranular twins The force during electrodeposition can be described by a critical shear twinning force rcrit, defined by equation 2 below:

[0049] (2)

[0050] where b is a Burgers vector representing the amplitude and direction of the lattice distortion resulting from a dislocation in a crystal lattice. Since the critical shear twinning force is lower when the stacking defect energy is lower, increasing the cobalt concentration in the nickel-cobalt alloy promotes intragranular twinning. Strain twins can also form in the nickel-cobalt 100 material under an applied load such as a resonant vibration.

[0051] Intragranular twins (such as the first and second twins 111,112) formed during heat treatment can be referred to as annealing twins. The probability of forming annealing twins p can be described with respect to the grain size D and a material-dependent constant B, which is inversely proportional to the stacking defect energy, as defined by equation 3 below:

[0052] (3) p=Bl

[0053] where Do is the grain size for which p is zero. Since B is inversely proportional to the stacking defect energy, a low stacking defect energy associated with an increase in the cobalt concentration in the nickel-cobalt 100 material also promotes the formation of annealed twins.

[0054] Individually or in combination, the presence of phosphorus precipitants 120 that anchor the grain boundaries 106 of the nickel-cobalt material 100, or the intragranular anchoring attributable to the high level of cobalt in the nickel-cobalt material 100, can allow for increased thermal stability of the nickel-cobalt material 100. Thermal stability can be characterized relative to the starting temperature Tstart for grain growth in the nickel-cobalt alloy. Generally, the starting temperature for grain growth in a nickel-cobalt alloy corresponds to approximately 40% of the melting temperature Tmelt for the alloy. However, the introduction of phosphorus precipitants 120 or a high level of cobalt can increase the starting temperature, respectively by anchoring and by intragranular twinning.In some aspects, the starting temperature Tstart for grain growth in the nickel-cobalt 100 material can be increased up to about 50% or 60% of the melting temperature Tfusion for the alloy.

[0055] With reference now to [Fig. 5], the phosphorus-130 doped nickel-cobalt precursor material is shown with a group of nanocrystalline nickel-cobalt grains untwinned and unheat-treated grains, referred to herein as untreated grains 170. The untreated grains 170 of the precursor material 130 are represented as untwinned grains. Some of the untreated grains 170 may exhibit twinning, and it is also expected that some of the untreated grains 170 may have a single grain orientation after electrodeposition.

[0056] Figure 6 represents the precursor material 130 of Figure 5 after heat treatment as described above to form the heat-treated nickel-cobalt material 100 comprising untwinned grains 101 and twinned grains 102. As described above, the heat treatment may include at least one heating to a temperature, or within a temperature range, lower than the starting temperature of grain growth in the doped nickel-cobalt precursor material 130, including heating within a temperature range of approximately 650 K to approximately 700 K, to form the heat-treated nickel-cobalt material 100. The heat treatment may form twinned grains 102. The heat treatment may also form phosphorus precipitates 120 along the grain boundaries 160 as shown, or in grains 101, 102 (not shown for clarity). Phosphorus-120 precipitates can allow Zener anchoring as described above.

[0057] Intragranular twinning can also occur under high-temperature or high-stress operating conditions, which enhances the thermal stability of components formed from the nickel-cobalt 100 material presented here. Intragranular twinning can occur as a consequence of shear stresses introduced through grain growth, which can arise due to stacking defects at migrating grain boundaries, but also due to grain boundary dissociation, grain encounters, or growth accidents.

[0058] An example of crack propagation or fracture path 190 is shown in the nickel-cobalt material 100, for example under cyclic stress or tensile stress. The fracture path 190 is illustrated with both an intragranular and a transgranular fracture mode. Four cases of parts of the fracture path 190 are shown by way of example. A first part 191 follows a first twin 111 of a twinned grain 102 in a transgranular fracture mode. A second part 192 follows a grain boundary 106 in an intergranular fracture mode. A third part 193 follows a first twin 111 of another twinned grain 102 in a transgranular fracture mode, and a fourth part 194 crosses the first and second twins 111, 112 of another twinned grain 102 in a different transgranular fracture mode.

[0059] In comparison, a crack propagation path in a conventional nickel-cobalt alloy tends to follow an intergranular fracture mode along grain boundaries, which occurs with a relatively low tensile stress compared to a transgranular failure mode. It should be noted that the heat-treated nickel-cobalt material 100 has greater strength than other conventional nickel-cobalt alloys.

[0060] With reference to [Fig. 7], Figure 200 shows examples of stress-strain curves that illustrate the effects of intragranular twinning. A nanocrystalline grain structure exhibiting both anchoring and intragranular twinning can exhibit improved strength or ductility compared to a nanocrystalline grain structure exhibiting only anchoring. Intragranular twinning provides additional interfacial barriers in the form of coherent twinning joints that contribute to tensile strength in a similar way to reduced grain size, but these coherent twinning joints provide slip planes that can contribute to ductility. The slip plane at the intragranular twinning joints can contribute to increased ductility to varying degrees depending on the geometric configurations and local stresses.

[0061] Figure 8 shows a curve 300 representing the stacking fault energy of the Nickel-cobalt alloys as a function of cobalt content. As can be seen, the stacking defect energy of the nickel-cobalt alloy decreases as the percentage of cobalt in the alloy decreases. For example, a nickel-cobalt alloy containing approximately 10% cobalt may have a stacking defect energy of approximately 125 mJ / m², while the alloy may have a stacking defect energy of approximately 75 mJ / m² with approximately 30% cobalt, or approximately 40 mJ / m² with approximately 40% cobalt. Nickel-cobalt alloys such as nickel-cobalt 100 material may have a greater propensity to produce twinning, compared to unalloyed nickel, due to a decrease in stacking defect energy (SFE). Increasing the percentage of cobalt in the nickel-cobalt 100 material, which can go up to a concentration of about 50%, can further reduce the stacking defect energy, as shown in [Fig.8].Controlling and adjusting the cobalt concentration can also be used to improve ductility, as well as thermal strengthening and distortion resistance. For example, the stacking defect energy for a 100% Ni material is approximately 125 mJ / m². For a NiCo alloy with 30% cobalt, it is reduced to approximately 75 mJ / m², and it can be further reduced to approximately 40 mJ / m² with 40% cobalt.

[0062] Figure 9 represents a graph 400 that shows the fatigue resistance in The grain size function for an example metal, specifically stainless steel such as SS304, is shown. The grain sizes represented are: 47 µm (plot with circles), 17 µm (plot with triangles), and 3 µm (plot with squares). For example, stainless steel can be subjected to cyclic loading, and fatigue strength can be measured by the number of cycles until the The material exhibits fatigue, for example by fracture, under a range of external stresses. All grain sizes shown show greater fatigue strength at lower external stresses. Furthermore, all grain sizes have an "infinite time strength," in which the number of cycles to fracture is extremely high, or "infinite," for stresses less than or equal to a certain external stress. For example, if the material in question is used for a component subjected to external stresses at or below the material's "infinite time strength," this component is not expected to experience in-service fatigue (e.g., crack propagation) over its lifetime. Overall fatigue crack strength is increased with smaller grain sizes, as can be seen in Figure 400.Grain size, the number of twins, and the thickness or width of the twins can affect crack propagation and the magnitude of the material's infinite strength.

[0063] Figure 10 shows a 500 graph that displays the fatigue strength as a function of grain size for another example of a metal in the form of electroplated nickel. The grain sizes shown are nanocrystalline nickel, ultrafine-grained nickel, and microcrystalline nickel. Similar to Figure 9, the overall fatigue crack strength increases with decreasing grain size.

[0064] With reference to Figures 9 and 10, it should be noted that certain aspects of the nickel-cobalt 100 material as described herein allow for increased fatigue strength at small grain sizes. For example, the nickel-cobalt 100 material can have a grain size less than 100 nm, for example, approximately 85 nm. A direct relationship has been established between the size or width of the grains and twins and crack initiation and fatigue fracture stress. In this case, crack initiation occurred at higher stresses for materials with nanometric grains than for materials with larger grain sizes. The nanocrystalline nickel-cobalt 100 material can also exhibit high fatigue fracture strength, or material fracture toughness. In one example, nickel-cobalt material can exhibit a tensile strength of approximately 10 MPa-m1 / 2 to 70 MPa-m1 / 2.In another example, the nickel-cobalt 100 material can exhibit a Vickers hardness greater than 400 Hv.

[0065] A method for manufacturing a material such as nickel-cobalt material 100 comprises forming a doped nickel-cobalt precursor material 100 by means of an electrodeposition process and heat-treating the doped nickel-cobalt precursor material 100, wherein the heat treatment comprises at least heating to a temperature lower than the starting temperature of grain growth in the doped nickel-cobalt precursor material 100 to form a material Heat-treated nickel-cobalt 100. The doped nickel-cobalt precursor material 100 may comprise at least one of a phosphorus-doped nickel-cobalt material and a boron-doped nickel-cobalt material, as described above. Optionally, an example using a phosphorus-doped nickel-cobalt material may comprise approximately 30% to 35% by atomic mass of cobalt, approximately 1000 ppm to 1500 ppm by atomic mass of phosphorus, and nickel as a complement to the material.

[0066] The heat treatment can form at least one element among phosphorus precipitates at the nanocrystalline grain boundaries and intragranular twinning, as described above. The phosphorus-doped nickel-cobalt material can have a nanocrystalline grain structure with a grain size distribution of approximately 50 to 100 nanometers. The phosphorus-doped nickel-cobalt material can exhibit a fracture toughness of approximately 10 MPa-m1 / 2 to 70 MPa-m1 / 2, an ultimate tensile strength of approximately 1,000 MPa to approximately 1,500 MPa, and it can have increased thermal stability with a starting temperature equal to approximately 50% or 60% of the melting temperature for the alloy described above. Furthermore, the process can also include the transformation of the heat-treated nickel-cobalt material into an aircraft component as described above.

[0067] Aspects of the disclosed nickel-cobalt material as described herein provide various advantages, including improved fatigue strength and material hardness. Aspects of the invention provide a novel electroplated nanocrystalline nickel-based alloy exhibiting excellent thermal stability, high low-cycle fatigue strength, and high high resistance to multi-cycle fatigue cracking. This results in the efficient use of the material via the electrodeposition process for a wide range of components, including turbine engine components subjected to various stress and fatigue conditions.

[0068] In a manner not yet described, the various features and structures of the different embodiments can be freely combined. The fact that a feature is not illustrated in all embodiments does not mean that it cannot be; this is done simply to simplify the description. Thus, the various features of the different embodiments can be mixed and combined at will to form new embodiments, whether or not these new embodiments are expressly described. All combinations or permutations of the features described herein are covered by this invention.

[0069] This written description uses examples to describe the invention, including the best method, and also to enable any person of the the business of putting the invention into practice, including manufacturing and using any device or system and implementing any incorporated process.

[0070] Other aspects of the invention are given below.

[0071] A method for manufacturing a material is proposed, the method comprising the formation of a doped nickel-cobalt precursor material, and the heat treatment of the doped nickel-cobalt precursor material, wherein the heat treatment comprises at least heating to a temperature lower than the starting temperature of grain growth in the doped nickel-cobalt precursor material to form a heat-treated nickel-cobalt material.

[0072] Preferably, the doped nickel-cobalt precursor material comprises at least one material from a phosphorus-doped nickel-cobalt material and a boron-doped nickel-cobalt material.

[0073] Advantageously, the phosphorus-doped nickel-cobalt material may comprise about 25% to about 40% by atomic mass of cobalt, about 1,000 ppm to about 3,500 ppm by atomic mass of phosphorus, and nickel as a complement to the material.

[0074] According to one embodiment, heat treatment forms phosphorus precipitates at nanocrystalline grain boundaries.

[0075] According to one embodiment, the heat treatment forms an intra-granular twin.

[0076] According to one embodiment, the heat-treated nickel-cobalt material comprises a nanocrystalline grain structure having a grain size distribution of approximately 50 to 100 nanometers.

[0077] According to one embodiment, the heat-treated nickel-cobalt material has a tensile strength of about 10 MPa-m1 / 2 to 70 MPa-m1 / 2.

[0078] Preferably, the heat treatment further comprises a heat treatment in a temperature range from about 600 K to about 750 K.

[0079] According to one embodiment, the heat-treated nickel-cobalt material has an ultimate tensile strength of about 1,000 MPa to about 1,500 MPa.

[0080] According to one embodiment, the formation of a doped nickel-cobalt precursor material further comprises the electroforming of the doped nickel-cobalt precursor material.

[0081] A component is also proposed comprising a body in which at least a part thereof comprises a thermally stabilized nickel-cobalt alloy with nanocrystalline grain structures, an anchoring and intragranular twinning which exhibits a fracture toughness of about 10 MPa-m1 / 2 to 70 MPa-m1 / 2, increased thermal stability with a starting temperature equal to about 50% or 60% of the melting temperature of the alloy, and an ultimate tensile strength of about 1,000 MPa to about 1,500 MPa.

[0082] Preferably, the nanocrystalline grain structure comprises a grain size distribution from about 50 nanometers to about 100 nanometers.

[0083] According to one embodiment, the nickel-cobalt alloy comprises a chemical composition comprising approximately 30% to approximately 35% by atomic mass of cobalt, approximately 1,000 ppm to approximately 1,500 ppm by atomic mass of phosphorus or boron, and nickel as a complement to the material.

[0084] A nickel-cobalt type material is also proposed comprising a nanocrystalline grain structure having a grain size distribution of about 50 nanometers to about 110 nanometers, the nanocrystalline grain structure comprising phosphorus precipitates at nanocrystalline grain boundaries and intragranular twinning, the material having a chemical composition comprising about 25% to about 40% by atomic mass of cobalt, about 1,000 ppm to about 3,500 ppm by atomic mass of phosphorus or boron, and nickel.

[0085] Preferably, nickel forms the complement of the material.

[0086] Advantageously, the fatigue crack resistance in the nickel-cobalt material is increased with a reduced nanocrystalline grain size.

[0087] According to one embodiment, the nickel-cobalt material has a Vickers hardness greater than 400 Hv.

[0088] According to one embodiment, the nickel-cobalt material has a tensile strength of about 10 MPa-m1 / 2 to 70 MPa-m1 / 2.

[0089] According to one embodiment, the nickel-cobalt material exhibits increased thermal stability with a starting temperature equal to approximately 50% or 60% of the melting temperature of the alloy.

[0090] According to one embodiment, the nickel-cobalt material has an ultimate tensile strength of about 1,000 MPa to about 1,500 MPa.

Claims

Demands

1. Component comprising a body in which at least a portion thereof comprises a thermally stabilized nickel-cobalt alloy with nanocrystalline grain structures, intragranular anchoring and twinning which exhibits a tensile strength of 10 MPa-m1 / 2 to 70 MPa-m1 / 2, increased thermal stability with a starting temperature equal to 50% or 60% of the alloy's melting temperature, and an ultimate tensile strength of 1,000 MPa to 1,500 MPa.

2. Component according to claim 1, wherein the nanocrystalline grain structure comprises a grain size distribution from 50 nanometers to 100 nanometers.

3. Component according to claim 1 or 2, wherein the nickel-cobalt alloy comprises a chemical composition comprising 30% to 35% by atomic mass of cobalt, 1,000 ppm to 1,500 ppm by atomic mass of phosphorus or boron, and nickel as a complement to the material.