Connection method of FGH99 double-spoke turbine disk based on nano-high entropy alloy intermediate layer

Abstract

The present invention discloses a connection method for an FGH99 double-spoke turbine disk based on a nanometer-sized high-entropy alloy intermediate layer, which belongs to the field of welding technology. The present invention adopts a high-entropy alloy intermediate layer, combines nanometer-sized treatment to optimize the microstructure, places the nanometer-sized high-entropy alloy intermediate layer between the upper and lower FGH99 double-spoke turbine disks, and performs diffusion connection in a vacuum diffusion welding furnace to obtain a welded FGH99 double-spoke turbine disk. Low-damage solid-phase diffusion connection is achieved at a welding temperature lower than the solid solution temperature of the parent material. At the same time, the nanometer-sized intermediate layer structure promotes element diffusion, which can greatly shorten the diffusion welding cycle, solve the problems of grain coarsening and heat-affected zone performance degradation caused by long-term heat preservation in traditional processes, break through the technical bottleneck of coordinated regulation of strength and toughness of the connection interface of complex components of high-temperature alloys, and provide a high-reliability solution for the efficient manufacturing of double-spoke turbine disks of aircraft engines, which is particularly suitable for long-life service requirements under extremely high temperature and cyclic load conditions.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and in particular to a method for connecting an FGH99 double-spoke turbine disk based on a nano-high entropy alloy intermediate layer. Background Art

[0002] Against the backdrop of international competition for high thrust-to-weight ratios and lightweight aero-engines, twin-spoke turbine disks, core components of the hot section of next-generation engines, feature multi-cavity, thin-walled structures that achieve a 15%-20% weight reduction and improve cooling efficiency, but also significantly increase the complexity of thermomechanical loads under service conditions. The fabrication of these structures relies on the high-temperature strength, fatigue properties, and creep resistance of the FGH99 powder metallurgy nickel-based superalloy. However, the high-precision joining of the multi-spoke discs after separate forming has become a key technical bottleneck restricting reliability.

[0003] Due to the high volume fraction and low diffusion properties of the γ' strengthening phase in powder metallurgy superalloys, fusion welding faces challenges such as grain coarsening and crack susceptibility in the heat-affected zone (HAZ). Brazing, on the other hand, can easily produce brittle compounds, degrading joint performance. Solid-phase diffusion welding, due to its high joint strength, excellent weld precision, and minimal deformation, has become the mainstream process for joining twin-spoke turbine disks. However, traditional solid-phase diffusion welding uses a nickel-based intermediate layer, which relies on high temperature (usually ≥1100℃) and long-term insulation (>150min) to promote element diffusion. However, the nickel-based intermediate layer has a low degree of alloying and insufficient interdiffusion efficiency with the parent material elements, which easily forms γ'-poor phase regions and coarse grain boundaries at the interface. At the same time, the slow diffusion of elements such as Cr and Mo leads to composition segregation at the interface, inducing the formation of brittle intermetallic compounds, seriously deteriorating the joint performance. In addition, high welding temperature and long-term insulation can easily cause the coarsening of the parent material's γ' strengthening phase, deteriorating the matrix performance, exacerbating the deformation risk of the turbine disk's precision structure, and restricting the dimensional accuracy and service reliability of the double-spoke plate components. Therefore, there is an urgent need for a technical solution that can solve the insufficient strength and toughness and thermal damage sensitivity of the solid-phase connection of the double-spoke plate turbine disk. Summary of the Invention

[0004] The purpose of the present invention is to provide a diffusion bonding method for FGH99 double-spoke turbine disks based on a nano-sized high-entropy alloy intermediate layer, so as to solve the technical bottlenecks of uncontrollable brittle phases, long isothermal solidification cycles and significant thermal damage to the parent material caused by the single composition of the intermediate layer in traditional solid-phase diffusion welding. The present invention proposes an innovative process of combining a multi-principal element high-entropy alloy intermediate layer with nano-sized interface activation, which suppresses the generation of brittle phases through the high entropy effect, accelerates element diffusion by nano-sizing the intermediate layer through laser shock, and realizes short-time, efficient and high-strength and tough connections.

[0005] To achieve the above objectives, the present invention proposes a method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer, comprising the following steps:

[0006] A high-entropy alloy intermediate layer is prepared, wherein the chemical composition of the high-entropy alloy intermediate layer is composed of Ni 18%, Co 17%, Cr 14%, W 12.3%, Ta 12.1%, Mo 11.2%, Nb 9.6%, and Ti 5.8% by mass;

[0007] The high entropy alloy intermediate layer is treated by laser shock treatment to obtain a nano-sized high entropy alloy intermediate layer, wherein the surface of the nano-sized high entropy alloy intermediate layer forms a gradient nanostructure and the surface grain size is 20nm-50nm;

[0008] A nano-sized high-entropy alloy intermediate layer is placed between the upper and lower layers of FGH99 double-spoke turbine disks, and diffusion bonding is performed in a vacuum diffusion welding furnace to obtain a welded FGH99 double-spoke turbine disk.

[0009] Preferably, the process of preparing the high entropy alloy intermediate layer comprises the following steps:

[0010] Step 1: Ni, Co, Cr, W, Ta, Mo, Nb, and Ti metal powders are mixed in proportion, placed in a high-energy ball mill, and ball milled under argon protection to obtain nano-scale composite powders;

[0011] Step 2: melting the nano-scale composite powder in a vacuum induction melting furnace and casting it into an ingot;

[0012] Step 3: The ingot is subjected to multiple hot rolling and multiple cold rolling to obtain a high entropy alloy intermediate layer foil with a thickness of 80 μm-100 μm.

[0013] Preferably, in the ball milling process in step 1, the ball-to-material ratio is 8:1-12:1, the ball milling speed is 300 rpm-500 rpm, and the ball milling time is 10 h-15 h.

[0014] Preferably, the grain size of the nano-scale composite powder is ≤100 nm.

[0015] Preferably, the vacuum degree of the vacuum induction melting furnace in step 2 is ≤1×10 -3 Pa, the melting temperature is 1650℃.

[0016] Preferably, in the multi-pass hot rolling process in step 3, the ingot is placed in a box-type resistance furnace and first rolled at 1100° C.-1150° C. for two passes, with a single reduction of 20%-25% and a rolling speed of 0.5 m / s-1.0 m / s, followed by single-pass rolling at 1050° C.-1100° C. with a single reduction of 15%-20% and a rolling speed of 1.0 m / s-1.5 m / s;

[0017] During the multi-pass cold rolling process, the hot-rolled billet is first rolled at room temperature for 1-3 passes, with a single reduction of 15%-20% and a rolling speed of 0.3m / s-0.5m / s, and then rolled at room temperature for 4-6 passes, with a single reduction of 10%-15% and a rolling speed of 0.5m / s-0.8m / s. The surface roughness of the obtained high-entropy alloy intermediate layer foil is Ra≤0.8μm.

[0018] Preferably, in the process of laser shock treatment of the high entropy alloy intermediate layer, the laser energy is 6J-10J and the energy density is 6GW / cm 2 -10 GW / cm 2 , pulse width 8ns-15ns, impact times 3-5 times.

[0019] Preferably, during the diffusion bonding process in the vacuum diffusion welding furnace, the heating temperature is 1060° C.-1110° C., the heating rate is 10° C. / min, the pressure is 6 MPa-10 MPa, and the holding time is 55 min-65 min.

[0020] Preferably, before placing the nano-high entropy alloy intermediate layer between the upper and lower FGH99 double-spoke turbine disks, the surface of the FGH99 double-spoke turbine disk to be welded is ground, polished, cleaned and dried.

[0021] Preferably, the grinding is performed using 160#~2000# sandpaper, the polishing is performed using silicon dioxide polishing liquid, the cleaning is performed using anhydrous ethanol for ultrasonic cleaning, the ultrasonic frequency is 20kHz, the cleaning time is 15 minutes, and the drying is performed using a nitrogen gun.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention proposes an innovative solid-phase diffusion bonding system based on a multi-principal element high-entropy alloy interlayer. Through high-entropy design of eight elements (Ni, Co, Cr, W, Ta, Mo, Nb, and Ti) combined with laser shock nanocrystallization, this system overcomes bottlenecks such as low weld metallization, brittle phase formation, and slow element diffusion caused by the traditional single-element interlayer composition. The multi-principal element high-entropy effect significantly improves weld metallization, thereby inhibiting the formation of brittle compounds. Combined with the gradient nanostructure induced by laser shock, this system overcomes the technical bottlenecks of slow diffusion dynamics, interface embrittlement, and high-temperature thermal damage associated with traditional processes. The W and Mo elements in the high-entropy alloy interlayer synergistically enhance high-temperature strength, while the Al element promotes densification of the surface oxide film. The nanograin boundaries and high-density dislocations formed by laser shock significantly enhance element diffusion rate, reduce welding temperature, shorten holding time, and eliminate the formation of continuous brittle phases at the joint interface. Through the synergistic effect of composition design, high-entropy effect, and gradient nanocrystallization, this system addresses the challenges of insufficient toughness and thermal damage sensitivity associated with solid-phase bonding of dual-spoke turbine disks, providing a highly efficient and low-cost solution for the high-reliability manufacturing of turbine disks for sixth-generation aircraft engines.

[0024] The present invention combines the gradient nanostructure induced by laser shock to reduce the activation energy of element diffusion by 30%-40%, thereby promoting element diffusion and achieving the same welding effect under lower diffusion welding temperature and shorter holding time conditions, thereby significantly reducing the risk of γ' phase coarsening of the parent material; in addition, the composition of the high-entropy alloy intermediate layer designed by the present invention is highly compatible with the parent material, and the mutual diffusion balance of elements can be achieved without complex gradient design. The process stability is high and it is suitable for large-scale low-damage manufacturing of double-spoke turbine disks of aircraft engines, meeting the stringent requirements of high thrust-to-weight ratio engines for long life and high reliability of hot end components. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an SEM image of the diffusion welded joint microstructure of the FGH99 double-spoke turbine disk in Example 1 of the present invention.

[0026] Figure 2 This is an SEM image of the diffusion welded joint microstructure of the FGH99 double-spoke turbine disk in Comparative Example 1 of the present invention.

[0027] Figure 3 This is an SEM image of the diffusion welded joint microstructure of the FGH99 double-spoke turbine disk in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0028] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] The present invention proposes a method for connecting an FGH99 double-spoke turbine disk by diffusion bonding a nano-processed high-entropy alloy intermediate layer, which specifically includes the following steps:

[0030] Step 1: The surface of the FGH99 double-spoke turbine disk to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished with 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded part is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated workpiece;

[0031] Step 2: Assemble the processed workpieces, assemble the nano-high entropy alloy intermediate layer foil in the middle of the base material, and obtain a sandwich structure of double-spoke turbine disk half disk / nano-high entropy alloy intermediate layer / double-spoke turbine disk half disk;

[0032] The method for preparing the nano-sized high entropy alloy intermediate layer comprises the following steps:

[0033] Ni, Co, Cr, W, Ta, Mo, Nb, and Ti metal particle powders with a purity of 99.9% or higher and a particle size of 50 μm or less are mixed according to mass percentage (Ni 18%, Co 17%, Cr 14%, W 12.3%, Ta 12.1%, Mo 11.2%, Nb 9.6%, and Ti 5.8%), placed in a high-energy ball mill, and ball milled under argon protection with a ball-to-material ratio of 8:1-12:1, for example, 8:1, 10:1, and 12:1, a rotation speed of 300 rpm-500 rpm, for example, 300 rpm, 400 rpm, and 500 rpm, and a ball milling time of 10 h-15 h, for example, 10 h, 12 h, and 15 h, to obtain a nano-scale composite powder with a grain size of 100 nm or less;

[0034] The ball-milled powder was placed in a vacuum induction melting furnace and heated to a temperature of ≤1×10 -3Pa, melting temperature 1650 ℃ smelting into a uniform ingot, then through multiple hot rolling and cold rolling process into a foil with a thickness of 80-100 μm; first, the ingot is preheated, placed in a box-type resistance furnace, heated to 500-600 ℃, for example, 500 ℃, 550 ℃, 600 ℃, kept warm for 2 hours to eliminate casting stress, and then first at 1100-1150 ℃ range, for example, 1100 ℃, 1125 ℃, 1150 ℃, control the single pressure rate to 20%-25%, for example, 20%, 22%, 25%, and the rolling speed is 0.5-1.0 m / s, For example, it can be 0.5m / s, 0.75m / s, 0.1m / s, and two passes of blank rolling are performed; in the finishing rolling stage, rolling is performed at a temperature range of 1050-1100°C, for example, 1050°C, 1075°C, 1100°C, and the single pressure reduction rate is controlled at 15%-20%, for example, 15%, 17%, 20%, and the rolling speed is 1.0-1.5m / s, for example, 1.0m / s, 1.25m / s, 1.5m / s. After each hot rolling, before air cooling to below 800°C, the hot rolling is immediately returned to the furnace and kept at the rolling temperature for 30 minutes (to prevent cracking caused by excessively low temperature); After cooling to room temperature, stress relief annealing is performed, and the temperature is kept at 500-600℃ (for example, 500℃, 550℃, 600℃) for 2 hours to eliminate rolling stress and provide a stable billet for cold rolling, and finally a uniform equiaxed hot-rolled billet with a thickness of 20-30mm is obtained, for example, the thickness can be 20mm, 25mm, 30mm; the hot-rolled billet is cut into strips with a width of 100-150mm, for example, 100mm, 125mm, 150mm, the surface is polished to remove the oxide film, and a cold rolling lubricant is applied; then the billet is subjected to multiple cold rolling passes, and a single downward pressing in the rough rolling stage (1-3 passes) is performed. The rate is 15-20%, for example, 15%, 17%, 20%, and the rolling speed is 0.3-0.5 m / s, for example, 0.3 m / s, 0.4 m / s, 0.5 m / s; the single pressing rate in the finishing rolling stage (4-6 passes) is 10-15%, for example, 10%, 13%, 15%, and the rolling speed is 0.5-0.8 m / s, for example, 0.5 m / s, 0.65 m / s, 0.8 m / s, and finally a foil with a thickness of 80-100 μm, for example, 80 μm, 90 μm, 100 μm, and a surface roughness Ra ≤ 0.8 μm.

[0035] The foil is subjected to laser shock treatment with a laser energy of 6J-10J, for example, 6J, 8J, 10J, and an energy density of 6GW / cm 2 -10 GW / cm 2 , for example, 6 GW / cm 2 , 8GW / cm 2 , 10 GW / cm2 The pulse width is 8ns-15ns, for example, 8ns, 10ns, 12ns, 15ns, and the number of impacts is 3-5 times, for example, 3 times, 4 times, 5 times, so that the surface grains are refined to 20-30nm, the core grain size is ≤100nm, and a gradient nanostructure and high-density dislocations are formed.

[0036] Step 3: Place the sandwich structure of double-spoke turbine disc half disc / nano-high entropy alloy intermediate layer / double-spoke turbine disc half disc obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 1×10 -3 Pa, heat from room temperature to 300℃ at 10℃ / min, keep warm for 10min, then heat to 700℃ at 10℃ / min, keep warm for 10min, then heat to 1060℃-1110℃ at 10℃ / min, for example, 1060℃, 1070℃, 1090℃, 1110℃, keep warm for 55min-65min, for example, 55min, 60min, 65min, apply 6MPa-10MPa pressure during the heat preservation period, for example, 6MPa, 8MPa, 10MPa, release the pressure after the heat preservation is completed, cool to room temperature with the furnace, and perform non-destructive testing to obtain the welded FGH99 double-spoke turbine disk.

[0037] In some embodiments of the present invention, when the nanometer-sized high entropy alloy intermediate layer used in step 2 is diffusion-bonded to the FGH99 double-spoke turbine disk, the functions of the elements inside it are as follows: Ni is the main matrix element of the FGH99 parent nickel-based high-temperature alloy, ensuring that the crystal structure (FCC) of the intermediate layer matches that of the parent material, reducing interface lattice distortion, promoting atomic interdiffusion, and cooperating with Al and Ti in the parent material to inhibit the coarsening of the γ' phase during the welding thermal cycle; Co can form a substitutional solid solution in the nickel-based alloy, thereby improving the high-temperature creep resistance of the intermediate layer, and also reducing the precipitation tendency of topologically close-packed (TCP) brittle phases such as σ phase and Laves phase, thereby improving interface toughness, and optimizing the matching of the thermal expansion coefficients of the intermediate layer and the parent material, thereby reducing welding residual stress; Cr will undergo solid solution in the γ phase, thereby improving the high-temperature strength of the intermediate layer, and at the same time forming a continuous diffusion gradient with the Cr element in the parent material to avoid compositional abrupt changes. The high melting point (3422°C) and low diffusion coefficient of W can significantly improve the high-temperature deformation resistance of the intermediate layer and inhibit grain boundary sliding during welding thermal cycles. In addition, its atomic radius is significantly different from that of Ni, which will aggravate lattice distortion, promote high entropy effect, avoid local segregation of elements, and inhibit the precipitation of brittle phases. Ta is a strong γ' phase-forming element and can preferentially occupy atomic positions in the TCP phase, inhibiting its formation and playing a role in improving the high-temperature endurance strength of the interface. Mo is dissolved in the γ phase, which can significantly improve the high-temperature strength and creep resistance of the intermediate layer. It can also form a composite diffusion channel with W and Nb, playing a role in optimizing the distribution uniformity of refractory elements. Nb segregates at the grain boundaries to form stable NbC particles, pinning the grain boundaries and inhibiting grain coarsening. Nb can partially replace Ti in the γ' phase to form Ni3(Al, Nb) improves the high-temperature stability of the γ' phase; Ti is the core element of the γ' phase Ni3(Al, Ti) of the base material, which maintains the volume fraction of the γ' phase and prevents the decrease of interface strength. The addition of Ti will form TiN / TiC nanoparticles, which inhibit the grain growth of the welding heat affected zone and refine the structure.

[0038] In some embodiments of the present invention, the nano-high entropy alloy intermediate layer of the present invention can also be used to connect other powder metallurgy nickel-based high-temperature alloys, and the connected parent materials can also include FGH95 double-spoke turbine disc, FGH96 double-spoke turbine disc, FGH97 double-spoke turbine disc, FGH98 double-spoke turbine disc, etc.

[0039] The present invention will be further described below with reference to the embodiments.

[0040] Example 1

[0041] This embodiment provides a liquid phase diffusion welding method for an FGH99 double-spoke turbine disk based on a nano-high entropy alloy intermediate layer. The specific steps are as follows:

[0042] Step 1: The surface of the FGH99 double-spoke turbine disk to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished with 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded part is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated workpiece;

[0043] Step 2: Assemble the processed workpieces, assemble the nano-high entropy alloy intermediate layer foil in the middle of the base material, and obtain a sandwich structure of double-spoke turbine disk half disk / nano-high entropy alloy intermediate layer / double-spoke turbine disk half disk;

[0044] The method for preparing the nano-sized high entropy alloy intermediate layer comprises the following steps:

[0045] Ni, Co, Cr, W, Ta, Mo, Nb, and Ti metal particle powders with a purity of ≥99.9% and a particle size of ≤50 μm were mixed according to mass percentage (Ni 18%, Co 17%, Cr 14%, W 12.3%, Ta 12.1%, Mo 11.2%, Nb 9.6%, and Ti 5.8%), placed in a high-energy ball mill, and ball milled under argon protection (ball-to-material ratio 10:1, rotation speed 400 rpm, time 12 h) to obtain nano-scale composite powders with a grain size of ≤100 nm;

[0046] The ball-milled powder was placed in a vacuum induction melting furnace and heated to a temperature of ≤1×10 -3 Pa, melted at a melting temperature of 1650 ° C to form a uniform ingot, and then through multiple hot rolling and cold rolling, the total deformation is controlled at 90% to prepare a foil with a thickness of 80 μm;

[0047] The foil was laser-shocked (laser energy 8J, energy density 8GW / cm 2 , pulse width 10ns, impact number 4 times), so that the surface grains are refined to 20-30nm, the core grain size is ≤100nm, and a gradient nanostructure and high-density dislocations are formed.

[0048] Step 3: Place the sandwich structure of double-spoke turbine disc half disc / nano-high entropy alloy intermediate layer / double-spoke turbine disc half disc obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 1×10 -3Pa, the temperature was raised from room temperature to 300℃ at 10℃ / min, kept at this temperature for 10min, then raised to 700℃ at 10℃ / min, kept at this temperature for 10min, then raised to 1070℃ at 10℃ / min, kept at this temperature for 60min, and a pressure of 6MPa was applied during the holding period. After the holding period, the pressure was released, and the machine was cooled to room temperature. The welded FGH99 double-spoke turbine disk was obtained by non-destructive testing (the microstructure of the diffusion welded joint of the double-spoke turbine disk half is shown in Figure 2). Figure 1 shown).

[0049] Example 2

[0050] This embodiment provides a liquid phase diffusion welding method for an FGH99 double-spoke turbine disk based on a nano-high entropy alloy intermediate layer. The specific steps are as follows:

[0051] Step 1: The surface of the FGH99 double-spoke turbine disk to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished with 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded part is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated workpiece;

[0052] Step 2: Assemble the processed workpieces, assemble the nano-high entropy alloy intermediate layer foil in the middle of the base material, and obtain a sandwich structure of double-spoke turbine disk half disk / nano-high entropy alloy intermediate layer / double-spoke turbine disk half disk;

[0053] The method for preparing the nano-sized high entropy alloy intermediate layer comprises the following steps:

[0054] Ni, Co, Cr, W, Ta, Mo, Nb, and Ti metal particle powders with a purity of ≥99.9% and a particle size of ≤50 μm were mixed according to mass percentage (Ni 18%, Co 17%, Cr 14%, W 12.3%, Ta 12.1%, Mo 11.2%, Nb 9.6%, and Ti 5.8%), placed in a high-energy ball mill, and ball milled under argon protection (ball-to-material ratio 10:1, rotation speed 400 rpm, time 12 h) to obtain nano-scale composite powders with a grain size of ≤100 nm;

[0055] The ball-milled powder was placed in a vacuum induction melting furnace and heated to a temperature of ≤1×10 -3 Pa, melted at a melting temperature of 1650 ° C to form a uniform ingot, and then through multiple hot rolling and cold rolling, the total deformation is controlled to 85% to prepare a foil with a thickness of 90 μm;

[0056] The foil was subjected to laser shock treatment (laser energy 8J, energy density 8GW / cm², pulse width 10ns, and 4 shocks), which refined the surface grains to 20-30nm, the core grain size ≤100nm, and formed a gradient nanostructure with high-density dislocations.

[0057] Step 3: Place the sandwich structure of double-spoke turbine disc half disc / nano-high entropy alloy intermediate layer / double-spoke turbine disc half disc obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 1×10 -3 Pa, heated from room temperature to 300℃ at 10℃ / min, kept warm for 10min, then heated to 700℃ at 10℃ / min, kept warm for 10min, then heated to 1070℃ at 10℃ / min, kept warm for 60min, applied 6MPa pressure during the holding period, released the pressure after the holding period, cooled to room temperature with the furnace, and subjected to non-destructive testing to obtain the welded FGH99 double-spoke turbine disk.

[0058] Example 3

[0059] This embodiment provides a liquid phase diffusion welding method for an FGH99 double-spoke turbine disk based on a nano-high entropy alloy intermediate layer. The specific steps are as follows:

[0060] Step 1: The surface of the FGH99 double-spoke turbine disk to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished with 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded part is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated workpiece;

[0061] Step 2: Assemble the processed workpieces, assemble the nano-high entropy alloy intermediate layer foil in the middle of the base material, and obtain a sandwich structure of double-spoke turbine disk half disk / nano-high entropy alloy intermediate layer / double-spoke turbine disk half disk;

[0062] The method for preparing the nano-sized high entropy alloy intermediate layer comprises the following steps:

[0063] Ni, Co, Cr, W, Ta, Mo, Nb, and Ti metal powders with a purity of ≥99.9% and a particle size of ≤50 μm were mixed according to atomic percentage (Ni 18%, Co 17%, Cr 14%, W 12.3%, Ta 12.1%, Mo 11.2%, Nb 9.6%, and Ti 5.8%), placed in a high-energy ball mill, and ball milled under argon protection (ball-to-material ratio 10:1, rotation speed 400 rpm, time 12 h) to obtain nano-scale composite powders with a grain size of ≤100 nm;

[0064] The ball-milled powder was placed in a vacuum induction melting furnace and heated to a temperature of ≤1×10 -3 Pa, melted at a melting temperature of 1650 ° C to form a uniform ingot, and then through multiple hot rolling and cold rolling, the total deformation is controlled to 80% to prepare a foil with a thickness of 100 μm;

[0065] The foil was subjected to laser shock treatment (laser energy 8J, energy density 8GW / cm², pulse width 10ns, and 4 shocks), which refined the surface grains to 20-30nm, the core grain size ≤100nm, and formed a gradient nanostructure with high-density dislocations.

[0066] Step 3: Place the workpiece obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 1×10 -3 Pa, heated from room temperature to 300℃ at 10℃ / min, kept warm for 10min, then heated to 700℃ at 10℃ / min, kept warm for 10min, then heated to 1100℃ at 10℃ / min, kept warm for 60min, applied 6MPa pressure during the holding period, released the pressure after the furnace was cooled to room temperature, and subjected to non-destructive testing to obtain the welded FGH99 double-spoke turbine disk.

[0067] Comparative Example 1

[0068] This comparative example provides a liquid phase diffusion welding method for an FGH99 double-spoke turbine disk, and the specific steps are as follows:

[0069] Step 1: The surface of the double-spoke turbine disk to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished with 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded workpiece is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated workpiece;

[0070] Step 2: Assemble the processed workpieces, assemble the nano-high entropy alloy intermediate layer foil in the middle of the base material, and obtain a sandwich structure of double-spoke turbine disk half disk / nano-high entropy alloy intermediate layer / double-spoke turbine disk half disk;

[0071] The method for preparing the nano-sized high entropy alloy intermediate layer comprises the following steps:

[0072] Ni, Co, Cr, W, Ta, Mo, Nb, and Ti metal powders with a purity of ≥99.9% and a particle size of ≤50 μm were mixed according to atomic percentage (Ni 18%, Co 17%, Cr 14%, W 12.3%, Ta 12.1%, Mo 11.2%, Nb 9.6%, and Ti 5.8%), placed in a high-energy ball mill, and ball milled under argon protection (ball-to-material ratio 10:1, rotation speed 400 rpm, time 12 h) to obtain nano-scale composite powders with a grain size of ≤100 nm;

[0073] The ball-milled powder was placed in a vacuum induction melting furnace and heated to a temperature of ≤1×10 -3 Pa, melted at a melting temperature of 1650 ° C to form a uniform ingot, and then through multiple hot rolling and cold rolling, the total deformation is controlled at 90% to prepare a foil with a thickness of 80 μm;

[0074] Step 3: Place the sandwich structure of double-spoke turbine disc half disc / nano-high entropy alloy intermediate layer / double-spoke turbine disc half disc obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 1×10 -3 Pa, the temperature was raised from room temperature to 300℃ at 10℃ / min, kept at this temperature for 10min, then raised to 700℃ at 10℃ / min, kept at this temperature for 10min, then raised to 1070℃ at 10℃ / min, kept at this temperature for 60min, and a pressure of 6MPa was applied during the holding period. After the holding period, the pressure was released, and the machine was cooled to room temperature. The welded double-spoke turbine disk was obtained by non-destructive testing (the microstructure of the diffusion welded joint of the double-spoke turbine disk half is shown in Figure 2). Figure 2 shown).

[0075] Comparative Example 2

[0076] In the process of preparing the nano-high entropy alloy intermediate layer in this comparative example, Ni, Co, Cr, W, Ta, Mo, and Nb metal powders with a purity of ≥99.9% and a particle size of ≤50 μm were mixed according to mass percentage (Ni 20%, Co 18%, Cr 15%, W 12.3%, Ta 12.1%, Mo 12%, and Nb 10.6%), placed in a high-energy ball mill, and ball milled under argon protection (ball-to-material ratio 10:1, speed 400 rpm, time 12 h) to obtain a nano-scale composite powder with a grain size of ≤100 nm; the ball-milled powder was charged into a vacuum induction melting furnace and smelted under a vacuum degree of ≤1×10 -3 Pa, melted at a melting temperature of 1650 ° C to form a uniform ingot, and then through multiple hot rolling and cold rolling, the total deformation was controlled at 90% to prepare a foil with a thickness of 80 μm; the remaining steps were the same as those in Example 1. The microstructure of the diffusion welded joint of the FGH99 double-spoke turbine disk after welding is as follows Figure 3 shown.

[0077] Comparative Example 3

[0078] In the process of preparing the nano-high entropy alloy intermediate layer in this comparative example, Ni, Co, Cr, Ta, Mo, Nb, and Ti metal powders with a purity of ≥99.9% and a particle size of ≤50 μm were mixed according to atomic percentage (Ni 18%, Co 17%, Cr 14%, Ta 12.1%, Mo 23.5%, Nb 9.6%, and Ti 5.8%), placed in a high-energy ball mill, and ball milled under argon protection (ball-to-material ratio 10:1, rotation speed 400 rpm, time 12 h) to obtain a nano-scale composite powder with a grain size of ≤100 nm; the ball-milled powder was charged into a vacuum induction melting furnace and smelted under a vacuum degree of ≤1×10 -3 Pa, melted at a melting temperature of 1650°C to form a uniform ingot, and then subjected to multiple hot rolling and cold rolling passes with a total deformation of 90% to prepare a foil with a thickness of 80 μm; the remaining steps are the same as those in Example 1.

[0079] Comparative Example 4

[0080] In the process of preparing the nano-high entropy alloy intermediate layer in this comparative example, Ni, Co, Cr, W, Ta, Nb, and Ti metal powders with a purity of ≥99.9% and a particle size of ≤50 μm were mixed according to atomic percentage (Ni 18%, Co 17%, Cr 14%, W 23.5%, Ta 12.1%, Nb 9.6%, and Ti 5.8%), placed in a high-energy ball mill, and ball milled under argon protection (ball-to-material ratio 10:1, speed 400 rpm, time 12 h) to obtain a nano-scale composite powder with a grain size of ≤100 nm; the ball-milled powder was charged into a vacuum induction melting furnace and smelted under a vacuum degree of ≤1×10 -3 Pa, melted at a melting temperature of 1650°C to form a uniform ingot, and then subjected to multiple hot rolling and cold rolling passes with a total deformation of 90% to prepare a foil with a thickness of 80 μm; the remaining steps are the same as those in Example 1.

[0081] The tensile strength of the nano-high entropy alloy intermediate layer alloys in Examples 1-3, Comparative Examples 1-4 and the blank examples was tested at room temperature according to the standard "GB / T 228.1-2021: Tensile test of metallic materials - Part 1: Room temperature test method". The specific test results are shown in Table 1. The blank example is a powder metallurgy high-temperature alloy FGH99 base material.

[0082] Table 1 Tensile strength of joints in examples and comparative examples

[0083]

[0084] The test results in Table 1 show that the nano-high entropy alloy intermediate layer prepared by the present invention has good wettability and diffusivity. The nano-high entropy alloy intermediate layer provided by Example 1 has the best effect. The tensile strength of the joint reaches 90% of that of the parent alloy FGH99, and the weld strength is high. Observe the microstructure SEM images of the diffusion welded joints of the double-spoke turbine disks in Example 1 and Comparative Examples 1-2 of the present invention ( Figure 1-Figure 3 ), it can be seen that the welding effect of Example 1 of the present invention is the best, which is mainly because: from the scanning electron microscope (SEM) image, the interface between the nano-high entropy alloy intermediate layer and the base material is blurred, the element gradient transition is smooth, the continuous diffusion layer indicates sufficient metallurgical bonding, reducing the interface brittle phase, improving the tensile strength, and the connection interface defects are few; compared with the SEM image of the diffusion welded joint microstructure of the double-spoke turbine disk in Comparative Examples 1-2 of the present invention, the weld in Example 1 is well formed and no obvious defects are observed, indicating that the atomic diffusion is sufficient and the interface bonding force is strong, which is conducive to the joint to withstand external force and thus has higher strength. In addition, the picture shows that the grain size of the near-seam area and the weld of the weld joint is not significantly increased compared with the base material, indicating that the heat input is effectively controlled during the welding process and the thermal damage is small. It can be seen from the results of comparative example 1 that due to the lack of the laser shock step, the surface activation energy of the intermediate layer is low. Under the same welding parameters, the degree of element diffusion is not as good as that of Example 1. Compared with the joint structure under the same parameters, the weld width is the widest, and there are some hole defects, and the final tensile strength is poor. It can be seen from the microstructure SEM image of comparative example 2 that due to the lack of Ti element, the generation of γ' phase inside the joint is reduced, resulting in a decrease in joint strength. It can be seen from the tensile test results of comparative examples 1-3 that due to the lack of Ti, W or Mo elements in the nano-high entropy alloy intermediate layer, the tensile effect of the joint is significantly lower than that of Example 1.

[0085] The above contents are merely examples and explanations of the structure of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

[0086] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0087] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer, characterized in that: The following steps are involved: A high-entropy alloy intermediate layer is prepared, wherein the chemical composition of the high-entropy alloy intermediate layer is composed of Ni 18%, Co 17%, Cr 14%, W 12.3%, Ta 12.1%, Mo 11.2%, Nb 9.6%, and Ti 5.8% by mass; The high entropy alloy intermediate layer is treated by laser shock treatment to obtain a nano-sized high entropy alloy intermediate layer, wherein the surface of the nano-sized high entropy alloy intermediate layer forms a gradient nanostructure and the surface grain size is 20nm-50nm; A nano-sized high-entropy alloy intermediate layer is placed between the upper and lower layers of FGH99 double-spoke turbine disks, and diffusion bonding is performed in a vacuum diffusion welding furnace to obtain a welded FGH99 double-spoke turbine disk.

2. The method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer according to claim 1, characterized in that: The process of preparing the high entropy alloy intermediate layer comprises the following steps: Step 1: Ni, Co, Cr, W, Ta, Mo, Nb, and Ti metal powders are mixed in proportion, placed in a high-energy ball mill, and ball milled under argon protection to obtain nano-scale composite powders; Step 2: melting the nano-scale composite powder in a vacuum induction melting furnace and casting it into an ingot; Step 3: The ingot is subjected to multiple hot rolling and multiple cold rolling to obtain a high entropy alloy intermediate layer foil with a thickness of 80 μm-100 μm.

3. The method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer according to claim 2, characterized in that: During the ball milling process in step 1, the ball-to-material ratio is 8:1-12:1, the ball milling speed is 300 rpm-500 rpm, and the ball milling time is 10 h-15 h.

4. The method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer according to claim 2, characterized in that: The grain size of the nano-scale composite powder is ≤100 nm.

5. The method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer according to claim 2, characterized in that: The vacuum degree of the vacuum induction melting furnace in step 2 is ≤1×10 -3 Pa, the melting temperature is 1650℃.

6. The method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer according to claim 2, characterized in that: During the multi-pass hot rolling process in step 3, the ingot is placed in a box-type resistance furnace and first rolled at 1100°C-1150°C for two passes with a single reduction of 20%-25% and a rolling speed of 0.5m / s-1.0m / s, followed by a single-pass rolling at 1050°C-1100°C with a single reduction of 15%-20% and a rolling speed of 1.0m / s-1.5m / s; During the multi-pass cold rolling process, the hot-rolled billet is first rolled at room temperature for 1-3 passes, with a single reduction of 15%-20% and a rolling speed of 0.3m / s-0.5m / s, and then rolled at room temperature for 4-6 passes, with a single reduction of 10%-15% and a rolling speed of 0.5m / s-0.8m / s. The surface roughness of the obtained high-entropy alloy intermediate layer foil is Ra≤0.8μm.

7. The method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer according to claim 1, characterized in that: In the process of laser shock treatment of the high entropy alloy intermediate layer, the laser energy is 6J-10J and the energy density is 6 GW / cm 2 -10 GW / cm 2 , pulse width 8ns-15ns, impact times 3-5 times.

8. The method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer according to claim 1, characterized in that: During the diffusion bonding process in the vacuum diffusion welding furnace, the heating temperature is 1060° C.-1110° C., the heating rate is 10° C. / min, the pressure is 6 MPa-10 MPa, and the holding time is 55 min-65 min.

9. The method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer according to claim 1, characterized in that: Before placing the nano-high entropy alloy intermediate layer between the upper and lower FGH99 double-spoke turbine disks, the surface of the FGH99 double-spoke turbine disk to be welded is ground, polished, cleaned and dried.

10. The method for connecting FGH99 double-spoke turbine disks based on a nano-high entropy alloy intermediate layer according to claim 9, characterized in that: The grinding was performed using 160#~2000# sandpaper; the polishing was performed using silicon dioxide polishing liquid; the cleaning was performed using anhydrous ethanol for ultrasonic cleaning, with an ultrasonic frequency of 20kHz and a cleaning time of 15 minutes; and the drying was performed using a nitrogen gun.

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