Nickel-based composite pipe and preparation method thereof

Abstract

The invention relates to the technical field of metal materials, in particular to a nickel-based composite pipe and a preparation method thereof.The nickel-based composite pipe is formed by combining an outer metal layer, a powder metallurgy middle layer and an inner metal layer, the outer metal layer is a carbon steel or low alloy steel plate, and the inner metal layer is an austenitic stainless steel or duplex stainless steel or corrosion-resistant nickel-based alloy plate; the powder metallurgy middle layer is composed of a nickel-based alloy matrix and reinforcing phases distributed in the nickel-based alloy matrix in a dispersed mode, and more than 60% of the reinforcing phases are directly attached to the surfaces of the rare earth oxide particles serving as heterogeneous nucleation centers. Through the combination of at least two rare earth oxides, the reaction elements and the nickel-based matrix generate an ultra-fine, uniformly dispersed and high-proportion attached reinforced phase on the surface of the oxides in situ, and the problems that a traditional composite pipe is agglomerated in reinforced phase, weak in interface bonding, poor in high-temperature stability, concentrated in stress and difficult to consider both strength and toughness are solved.

Description

Technical Field

[0001] This invention relates to the field of metal materials technology, specifically to a nickel-based composite tube and its preparation method. Background Technology

[0002] In fields such as oil and gas extraction and transportation, chemical and metallurgical industries, pipeline systems are subjected to long-term erosion by high temperatures, high pressures, and highly corrosive media. Traditional single-material pipelines are insufficient to meet comprehensive performance requirements: carbon steel or low-alloy steel pipes are low in cost and high in strength, but have poor corrosion resistance and are prone to rapid corrosion and perforation in harsh environments, with a lifespan of only 5-8 years; while pipelines made entirely of corrosion-resistant materials such as austenitic stainless steel, duplex stainless steel, or nickel-based alloys have excellent corrosion resistance, but are expensive and some materials lack sufficient strength to withstand high pressures.

[0003] To balance performance and cost, bimetallic composite pipes have emerged. Currently, the mainstream technology involves preparing nickel-based composite plates through rolling or explosive bonding, followed by JCO forming and welding to create composite pipes. The overall cost of these composite pipes is 40-60% lower than that of solid alloy pipes, thus solving the problem to some extent.

[0004] However, existing composite pipe technology has inherent defects: the composite interface is a direct physical / metallurgical bond between two metals, and there are abrupt changes in chemical composition, mechanical properties, and coefficient of thermal expansion at the interface, forming a weak zone. Under the cyclic loads and thermal stresses during subsequent pipe bending, welding, and service, the interface is prone to peeling and cracking, becoming a source of failure. Furthermore, this interface layer itself does not possess any special strengthening function, serving only a connecting role. Under the effects of subsequent pipe bending, welding, and thermal cycling and mechanical vibrations during service, this weak zone is highly susceptible to becoming a stress concentration point and crack initiation source, leading to interface peeling or cracking, severely restricting the reliability and service life of the composite pipe. Summary of the Invention

[0005] This application provides a nickel-based composite tube and its preparation method to solve the problems of limited bonding strength, severe stress concentration and single function of the interface layer in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides a nickel-based composite tube, such as... Figure 1 As shown, the nickel-based composite tube is composed of an outer metal layer, a powder metallurgy intermediate layer, and an inner metal layer, wherein... The outer metal layer is carbon steel or low alloy steel plate, and the inner metal layer is austenitic stainless steel, duplex stainless steel or corrosion-resistant nickel-based alloy plate. The powder metallurgy intermediate layer is composed of a nickel-based alloy matrix and a reinforcing phase dispersed therein. The reinforcing phase is generated by in-situ reaction and is selected from at least one of titanium boride, chromium boride, and nickel-aluminum intermetallic compounds. More than 60% of the reinforcing phase is directly attached to the surface of rare earth oxide particles that serve as heterogeneous nucleation centers.

[0007] Based on the aforementioned technical means, this application embodiment introduces a powder metallurgy intermediate layer, transforming the easily failing weak interface region in traditional composite pipes into a functional gradient layer that combines high bonding strength with excellent intrinsic properties. The intermediate layer is metallurgically bonded to the inner and outer metal layers. Benefiting from the precise control of rare earth oxides on the nucleation and distribution of reinforcing phases, and the dispersed strengthening effect of various reinforcing phases (such as whiskers with high aspect ratios and fine particles) in the matrix, this composite pipe achieves high strength while maintaining good toughness and high-temperature structural stability, resulting in significantly superior overall performance compared to traditional composite pipes.

[0008] Furthermore, the total weight of the raw materials for the powder metallurgy intermediate layer is used as a basis: The content of the rare earth oxide powder is 0.05wt%-3.0wt%; The content of the reactive element powder is 2.0wt%-15.0wt%.

[0009] Furthermore, the titanium boride includes TiB whiskers and TiB2 particles, and the chromium boride includes CrB whiskers. The average diameter of the TiB whiskers and the CrB whiskers is less than 1 micrometer, and the aspect ratio is greater than 5. The nickel-aluminum intermetallic compound is Ni3Al or NiAl intermetallic compound particles, both with an average size of less than 2 micrometers.

[0010] Based on the aforementioned technical means, TiB or CrB whiskers with an average diameter of less than 1 micrometer and an aspect ratio greater than 5 in the embodiments of this application can form a micro-nano-scale reinforcing network in the nickel-based alloy matrix, effectively transferring loads and improving the strength and stiffness of the material. At the same time, the dispersed TiB2 particles and Ni3Al (or NiAl) particles can act as effective barriers to dislocation movement, providing continuous dispersion strengthening, thereby further consolidating the mechanical properties of the material.

[0011] It should be noted that the reinforcing phase in the powder metallurgy intermediate layer at least partially forms a multi-scale, multi-morphological synergistic strengthening structure. For example, the combination of TiB whiskers and TiB2 particles, or the combination of CrB whiskers and Ni3Al particles, can synergistically improve the strength, toughness, and creep resistance of the composite layer through multiple mechanisms such as whisker support, particle pinning, and interface synergy during material deformation.

[0012] Furthermore, the rare earth oxide particles are selected from at least two of yttrium oxide, cerium oxide, scandium oxide, and erbium oxide.

[0013] Based on the aforementioned technical means, in this embodiment, yttrium oxide, with its stable thermodynamic properties at high temperatures, acts as an inert heterogeneous nucleation core to pin grain boundaries, inhibiting abnormal grain growth and providing macroscopic high-temperature structural stability and creep resistance for the material. Meanwhile, other rare earth oxides, such as cerium oxide, utilize their higher interfacial activity to selectively agglomerate at the interface between the reinforcing phase and the nickel-based alloy matrix. This improves interfacial compatibility, reduces interfacial energy to strengthen metallurgical bonding, and provides more active heterogeneous nucleation cores, achieving a refined and uniform distribution of the reinforcing phase. Under this combined synergistic effect, the powder metallurgy intermediate layer possesses a fine and uniform reinforcing phase distribution, excellent interfacial bonding strength, and high-temperature stability, ultimately simultaneously improving the room-temperature strength, toughness, and long-term high-temperature service performance of the composite tube. Its overall effect is significantly better than the use of a single rare earth oxide.

[0014] Furthermore, the thickness of the powder metallurgy intermediate layer is 0.1mm-2.0mm.

[0015] Furthermore, the nickel-based alloy matrix is ​​nickel-chromium alloy powder, nickel-chromium-aluminum alloy powder, or nickel-based high-temperature alloy powder.

[0016] Based on the above technical means, this application embodiment addresses the core requirements of the powder metallurgy intermediate layer load-bearing reinforcement phase, compatibility with inner and outer metal layers, and different service scenarios, and designs three types of functionally differentiated powder matrix selections: Nickel-chromium alloy powder (such as the Inconel 600 series) is a general solution. Based on its excellent oxidation resistance and high-temperature corrosion resistance, it ensures good high-temperature strength and plasticity of the matrix through solid solution strengthening effect, achieving a balance between cost and performance while meeting the requirements of conventional working conditions. Nickel-chromium-aluminum alloy powders (such as Inconel 718) are designed for high-strength applications. By introducing aluminum, a dual strengthening mechanism is constructed. The aluminum element participates in the formation of an in-situ reinforcing phase of intermetallic compounds as a reactive element, and also precipitates a γ' (Ni3Al) precipitate strengthening phase in the matrix. The two effects work together to improve the mechanical properties of the material. Nickel-based superalloy powders (such as the Hastelloy series) focus on extreme high temperature, high pressure and corrosive conditions. Their composition is rich in multi-element strengthening elements such as W, Mo, Ta and Re, which have excellent comprehensive high temperature performance. They can ensure that the intermediate layer maintains stable structural integrity and performance reliability in harsh service environments for a long time, and are suitable for the special needs of cutting-edge industrial fields.

[0017] This application also proposes a method for preparing a nickel-based composite tube, comprising the following steps: S1. Prepare the outer metal plate and the inner metal plate separately, and clean and roughen the surfaces to be laminated; S2. Mix nickel-based alloy powder, rare earth oxide powder, and reactive element powder used for in-situ generation of reinforcing phase to obtain composite reinforced powder; S3. Spread the composite reinforcing powder on the surface of the inner metal plate or the outer metal plate, and then cover it with another metal plate to form a three-layer flat preform of "metal plate-powder layer-metal plate"; S4. The outer metal plate is covered on the inner metal plate covered with powder to form a plate-powder-plate preform, and then hot rolling composite is performed under a protective atmosphere; the heating temperature is 900-1150℃, and the total reduction rate is 30%-60%, so that the powder layer is densified and forms a strong metallurgical bond with the upper and lower metal plates to obtain a high-performance nickel-based composite plate. S5. The high-performance nickel-based composite plate is formed into a tube shape using JCO or UOE process and longitudinally welded to obtain a composite tube blank. The JCO forming adopts a multi-step progressive bending process, and the bending pressure in a single bending does not exceed 20% of the plate thickness. S6. The composite tube blank is heated to 1100-1250℃ under a protective atmosphere and held for 1-8 hours to trigger the in-situ reaction of the reactive element powder with the rare earth oxide particles as the core, generating the reinforcing phase, and finally achieving complete metallurgical bonding between the powder metallurgy intermediate layer and the inner and outer metal tubes, thus preparing the nickel-based composite tube.

[0018] Further, in step S3, before spreading the composite reinforcing powder, a nickel-based transition layer with a thickness of 10-50 micrometers is prepared on the surface of the metal plate, wherein the nickel-based transition layer is an electroplated nickel layer or a nickel-based alloy layer prepared by thermal spraying.

[0019] Furthermore, the reactive element powder is a combination of boron powder and titanium powder, a combination of boron powder and chromium powder, or aluminum powder; the nickel-based alloy powder is nickel-chromium alloy powder, nickel-chromium-aluminum alloy powder, or nickel-based high-temperature alloy powder.

[0020] The beneficial effects achieved by using the present invention described above are as follows: 1. This invention pre-defines at least two rare earth oxide combinations in the powder system. Thermodynamically stable yttrium oxide serves as an inert heterogeneous nucleation core, providing fixed nucleation sites for reinforcing phases such as titanium boride, chromium boride, and nickel-aluminum intermetallic compounds, inducing the directional growth of these reinforcing phases around this core. Active rare earth oxides such as cerium oxide, scandium oxide, and erbium oxide, with their high interfacial activity, selectively agglomerate at the reinforcing phase-matrix interface, reducing interfacial energy and increasing effective nucleation sites. Under the combined effects of high temperature (900-1150℃) and large deformation (30%-60% reduction), the rolling process simultaneously achieves instantaneous powder densification, interparticle metallurgical diffusion, and high-strength bonding of the three-layer metal interface within seconds. This not only shortens the traditional diffusion process, which requires several hours of heat preservation, to minutes, increasing production efficiency several times over, but more importantly, the intense plastic deformation breaks the surface oxide film, promoting close contact and atomic diffusion at the fresh metal interface. This allows the intermediate layer and the inner and outer metal layers to form a strong and tough metallurgical bond with a shear strength exceeding 200MPa immediately after rolling, laying a solid foundation for subsequent processing that far surpasses traditional processes. 2. Simultaneously, yttrium oxide, acting as a static Zener pinning point, exhibits stable thermodynamic properties at high temperatures, continuously inhibiting grain and reinforcing phase coarsening, locking in the microstructure, and ensuring that the material possesses both excellent creep resistance and structural stability during long-term high-temperature service. Active rare earth elements (derived from cerium / scandium / erbium oxides) segregate towards the interface at high temperatures, purifying interface impurities and reducing interface energy on the one hand, and dynamically repairing micro-damage generated during service on the other, inhibiting micro-crack propagation, and endowing the interface with excellent high-temperature stability and toughness. Combined with the multi-element reinforcing elements (W, Mo, Ta, Re, etc.) of the nickel-based matrix (such as the Hastelloy series), the composite tube can operate stably for a long time under extreme high-temperature, high-pressure, and highly corrosive environments, solving the problems of rapid high-temperature performance degradation and poor thermal stability of traditional composite tubes. 3. In this invention, the high aspect ratio TiB / CrB whiskers serve as a "load transfer skeleton," effectively bearing and dispersing stress, significantly improving the material's stiffness and strength. The dispersed TiB2 and Ni3Al / NiAl particles hinder dislocation movement through the Orowan mechanism, forming continuous dispersion strengthening. Rare earth oxide particles inhibit crack propagation and improve fracture toughness by pinning grain boundaries and deflecting microcracks. At the same time, active rare earth elements form stable chemical bonds at the interface, upgrading interface strengthening from traditional physical pinning to chemical bonding. The interface shear strength exceeds 150 MPa, and the room temperature yield strength of the composite tube is stable at ≥400 MPa, while maintaining excellent toughness, breaking through the technical bottleneck that strength and toughness cannot be achieved simultaneously in a single material. 4. This invention designs three types of nickel-based matrices for different service scenarios, achieving a precise match between performance and cost: nickel-chromium alloy powder serves as a general solution, balancing cost with basic corrosion resistance and high-temperature performance through solid solution strengthening, adapting to conventional operating conditions; nickel-chromium-aluminum alloy powder, through a dual mechanism of in-situ reinforcing phase and γ'(Ni3Al) precipitation strengthening, meets the needs of high-strength scenarios; and nickel-based high-temperature alloy powder focuses on extreme operating conditions, providing top-tier comprehensive high-temperature performance. Compared to monolithic corrosion-resistant alloy pipes, the composite pipe of this invention reduces costs by 40-60% while significantly improving overall performance, achieving a balance between economy and reliability. 5. This invention achieves segmented optimization of interface bonding and material strengthening through the effective synergy of "hot rolling composite" and "subsequent heat treatment." The hot rolling stage completes powder densification and initial strong metallurgical bonding of the interface in a single step, providing a dense and robust structural substrate for subsequent reactions. The subsequent heat treatment stage (1100-1250℃) precisely triggers in-situ reactions centered on rare earth oxides, generating a reinforcing phase and achieving atomic-level interdiffusion and complete metallurgical bonding between the intermediate layer and the inner and outer metal layers. An optional nickel-based transition layer further optimizes interface compatibility, transforming the abrupt interface of traditional direct "metal-metal" bonding into a gradient structure of "outer metal layer - functional intermediate layer - inner metal layer," completely eliminating stress concentration caused by abrupt changes in chemical composition and mechanical properties, and fundamentally solving the failure risks of easy peeling and cracking at the interface of traditional composite pipes.

[0021] This solves the problems of limited bonding strength, severe stress concentration, and limited functionality of the interface layer in existing technologies. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of the nickel-based composite tube provided in the embodiments of the present invention; Figure 2 This is a SEM schematic diagram of the powder metallurgy intermediate layer provided in Example 1 of the present invention; Figure 3 This is a SEM schematic diagram of the powder metallurgy intermediate layer provided in Example 2 of the present invention; Figure 4 This is a SEM schematic diagram of the powder metallurgy intermediate layer provided in Example 3 of the present invention; Figure 5 This is a SEM schematic diagram of the powder metallurgy intermediate layer provided in Example 4 of the present invention; Figure 6 This is a SEM schematic diagram of the powder metallurgy intermediate layer provided in Example 5 of the present invention; Figure 7This is a SEM schematic diagram of the powder metallurgy intermediate layer provided in Comparative Example 1 of this invention. Figure 8 This is a SEM image of the powder metallurgy intermediate layer provided in Comparative Example 2 of this invention. Figure 9 This is a SEM schematic diagram of the powder metallurgy intermediate layer provided in Comparative Example 3 of the present invention. Figure 10 This is a schematic diagram of the EDS of the powder metallurgy intermediate layer provided in Example 5 of the present invention; Figure 11 This is a TEM schematic diagram of the powder metallurgy intermediate layer provided in Example 5 of the present invention. Detailed Implementation

[0023] The technical solution of the present invention is illustrated below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0024] To better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. While exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0025] The following description, with reference to the accompanying drawings, illustrates an embodiment of a nickel-based composite tube and its preparation method. Addressing the limited bonding strength mentioned in the background section, this application provides a nickel-based composite tube. In this method, yttrium oxide is pre-combined with at least two rare earth oxides, such as cerium oxide, scandium oxide, or erbium oxide, in a powder system. Yttrium oxide acts as a thermodynamically stable inert heterogeneous nucleation core, providing fixed nucleation sites for reinforcing phases such as titanium boride, chromium boride, and nickel-aluminum intermetallic compounds. Active rare earth oxides segregate at the reinforcing phase-matrix interface, reducing interfacial energy and increasing nucleation sites. Simultaneously, yttrium oxide acts as a static Zener pinning point, suppressing grain growth at high temperatures. The coarsening of the reinforcing phase ensures creep resistance and structural stability, while active rare earth elements dynamically purify the interface and repair micro-damage. Combined with a nickel-based matrix containing multiple reinforcing elements such as W and Mo, the composite pipe can operate stably under extreme high-temperature, high-pressure, and highly corrosive environments. Furthermore, the load transfer effect of high aspect ratio whiskers, the Orowan reinforcement of dispersed particles, the crack deflection of oxides, and the interfacial chemical bonding achieve a breakthrough in performance, resulting in an interfacial shear strength >150MPa, a room-temperature yield strength ≥400MPa, and excellent toughness, overcoming the bottleneck of balancing strength and toughness. In addition, this invention designs three differentiated matrices: nickel-chromium alloy (general-purpose), nickel-chromium-aluminum alloy (high-strength), and nickel-based high-temperature alloy (extreme-condition type), adapting to different application scenarios. This reduces costs by 40-60% compared to overall corrosion-resistant alloy pipes. Through hot-rolling composite processes combined with an optional nickel-based transition layer, the traditional abrupt interface is transformed into a functionally graded structure, completely eliminating stress concentration and resolving the potential failure hazard of easy interface peeling and cracking. Ultimately, this achieves a balance between comprehensive performance, economy, and reliability.

[0026] All raw materials used in the embodiments of this application are commercially available industrial grade or higher products, with wide sources and stable supply: In the metal plates, the outer metal plate (carbon steel / low alloy steel) is selected from hot-rolled steel plates of grades such as Q345B, X65, and X70 that conform to GB / T1591-2008 or API5L standards, and is purchased from Baosteel and Ansteel steel enterprises; the inner metal plate (corrosion-resistant alloy) covers SUS304 and SUS316L austenitic stainless steel that conform to GB / T3280 and ASTMA240 standards, S32205 (2205) and S32750 (2507) duplex stainless steel that conform to ASTMA790 standards, and nickel-based corrosion-resistant alloys such as Inconel625, Inconel825, and Hastelloy C-276 (UNSN10276) that conform to ASTMB443 or B575 standards, and is purchased from CITIC Pacific Special Steel, Baowu Special Steel or Sandvik International suppliers. Nickel-based alloy powders include Ni-20Cr nickel-chromium alloy powder with a particle size of -300 mesh (≤48μm) and a purity of ≥99.5% (suppliers include Zhongnan Powder Metallurgy, GRINM Powder Materials, etc.), Inconel 718 nickel-chromium-aluminum alloy pre-alloyed powder with a particle size of -200 to -400 mesh, and Rene series and Hastelloy series nickel-based high-temperature alloy powders prepared by gas atomization with a particle size of -150 to -400 mesh (available from Oerlikon, Sandvik, etc.); among the reactive element powders, boron powder (purity ≥95%, particle size 1-10... The reagents (μm) were sourced from companies such as Aladdin and Sinopharm Chemicals. Titanium powder (prepared by the HDH method, purity ≥99%, particle size -400 mesh) was purchased from BaoTi Group. Chromium and aluminum powders were commercially available products with purity ≥99% and particle size -300 to -400 mesh. Rare earth oxide powders (yttrium oxide, cerium oxide, scandium oxide, erbium oxide) were high-purity nano or submicron-sized products with purity ≥99.9% and average particle size of 50nm-200nm. Suppliers included domestic companies such as Sinocera Materials and Jiangsu Bote, as well as international manufacturers such as Stanford Materials. Among the auxiliary materials, nickel salts and additives for electroplating nickel and NiCrBSi nickel-based alloy wires / powders for thermal spraying were all commercially available general-purpose products. Temporary adhesives included common chemical products such as polyvinyl butyral (PVB), paraffin wax, and polyacrylate. The encapsulation material was low-carbon steel or a plate of the same material as the pipe.

[0027] The nickel-based composite pipe and its preparation method provided by this invention possess complete industrial production implementation conditions and a strict quality control system, enabling large-scale mass production with stable and reliable product performance. The production process requires a dedicated workshop with an area of ​​no less than 24,200 square meters to meet the layout requirements of the entire process from raw material processing to finished product delivery. It also requires a complete power and utility system (including power distribution, compressed air, circulating cooling water, and air-cooled systems), a safety assurance system (such as fire-fighting equipment for workshop hoists), and the integration of a workshop intelligent digital control system (MES+), logistics AGVs, and a centralized control system. Through intelligent manufacturing, real-time monitoring and intelligent scheduling of the production process, material flow, and equipment status are achieved, ensuring precise execution of process parameters and traceability of the production process.

[0028] Core production and testing equipment is crucial for ensuring product quality. The metallurgical composite plate preparation and pipe manufacturing process utilizes the advanced "JCO submerged arc welding pipe manufacturing production line" (covering specifications from DN100 to DN500). Its "multi-step progressive bending" process is specifically designed for composite materials, perfectly protecting the powder metallurgy intermediate layer and composite interface from damage during the forming process. It is the core equipment for maintaining the structural integrity of the composite pipe. At the same time, it is equipped with a "fully automated ultrasonic flaw detection line" (covering DN100 to DN500) to conduct 100% full-coverage online non-destructive testing on the welded pipe blanks, comprehensively controlling the bonding quality of the composite interface, weld quality, and internal defects of the pipe body, thus building a solid defense line for product reliability.

[0029] The R&D and quality testing laboratory provides core support for product performance compliance and continuous technology optimization. The laboratory is equipped with a series of key equipment: for mechanical property testing, it has a universal testing machine (for room temperature / high temperature tensile, compression, and bending tests) and a low-temperature impact testing machine (for assessing material toughness); for microstructure analysis, it uses metallographic sample preparation equipment, metallographic microscopes, field emission scanning electron microscopes (SEM), and energy dispersive spectroscopy (EDS) to observe the morphology, distribution, and interfacial bonding of the reinforcing phase, completing micro-area composition analysis, which is an essential means to verify the core structure of "reinforcing phase adhering to the surface of rare earth oxides"; for composition control, it uses spectrometers and Malvern laser particle size analyzers to achieve rapid and accurate detection of the chemical composition and particle size distribution of raw material powders and finished products, ensuring formula consistency; in addition, it is equipped with precision measuring instruments such as electronic balances to provide auxiliary support for various testing and analysis.

[0030] The present invention will be further described in conjunction with the following embodiments.

[0031] Example 1 This invention provides a nickel-based composite tube, such as Figure 1 As shown, the nickel-based composite pipe is composed of an outer metal layer, a powder metallurgy intermediate layer, and an inner metal layer. The outer metal layer is carbon steel, and the inner metal layer is austenitic stainless steel; The powder metallurgy intermediate layer consists of a nickel-based alloy matrix and a reinforcing phase dispersed therein, wherein the reinforcing phase is generated by in-situ reaction and is selected from titanium borate, and more than 60% of the reinforcing phase is directly attached to the surface of rare earth oxide particles that serve as heterogeneous nucleation centers.

[0032] The total weight of the raw materials for the powder metallurgy intermediate layer is used as the basis: The content of rare earth oxide powder is 0.05 wt%; The content of the reactive element powder is 2.0 wt%.

[0033] The titanium borides include TiB whiskers and TiB2 particles. The average diameter of the TiB whiskers is less than 1 micrometer and the aspect ratio is greater than 5.

[0034] The rare earth oxide particles are selected from yttrium oxide and cerium oxide.

[0035] The thickness of the powder metallurgy intermediate layer is 0.1mm-2.0mm.

[0036] The nickel-based alloy matrix is ​​nickel-chromium alloy powder.

[0037] This application also proposes a method for preparing a nickel-based composite tube, comprising the following steps: S1. Prepare the outer metal plate and the inner metal plate separately, and clean and roughen the surfaces to be laminated; S2. Mix nickel-based alloy powder, rare earth oxide powder, and reactive element powder used for in-situ generation of reinforcing phase to obtain composite reinforced powder; S3. Spread the composite reinforcing powder on the surface of the inner or outer metal plate, and then cover it with another metal plate to form a three-layer flat preform of "metal plate-powder layer-metal plate". S4. The outer metal plate is covered on the inner metal plate covered with powder to form a plate-powder-plate preform, and then hot rolling composite is carried out under a protective atmosphere; the heating temperature is 900℃ and the total reduction rate is 30%-60%, which makes the powder layer dense and forms a strong metallurgical bond with the upper and lower metal plates to obtain a high-performance nickel-based composite plate. S5. The high-performance nickel-based composite plate is formed into a tube shape by JCO or UOE process and longitudinally welded to obtain a composite tube blank. The JCO forming adopts a multi-step progressive bending process, and the bending pressure in a single bending does not exceed 20% of the plate thickness. S6. The composite tube blank is heated to 1100℃ and held for 8 hours under a protective atmosphere to trigger the in-situ reaction of the reactive element powder with rare earth oxide particles as the core, generating a reinforcing phase, and finally achieving complete metallurgical bonding between the powder metallurgy intermediate layer and the inner and outer metal tubes, thus preparing a nickel-based composite tube.

[0038] In step S3, before spreading the composite reinforcing powder, a nickel-based transition layer with a thickness of 10-50 micrometers is prepared on the surface of the metal plate. The nickel-based transition layer is an electroplated nickel layer or a nickel-based alloy layer prepared by thermal spraying.

[0039] The reactive element powder is a combination of boron powder and titanium powder; the nickel-based alloy powder is a nickel-chromium alloy powder.

[0040] Example 2 This invention provides a nickel-based composite tube, such as Figure 1 As shown, the nickel-based composite pipe is composed of an outer metal layer, a powder metallurgy intermediate layer, and an inner metal layer. The outer metal layer is made of low-alloy steel plate, and the inner metal layer is made of duplex stainless steel. The powder metallurgy intermediate layer consists of a nickel-based alloy matrix and a reinforcing phase dispersed therein. The reinforcing phase is generated by in-situ reaction and is selected from titanium boride and chromium boride. More than 60% of the reinforcing phase is directly attached to the surface of rare earth oxide particles that serve as heterogeneous nucleation centers.

[0041] The total weight of the raw materials for the powder metallurgy intermediate layer is used as the basis: The content of rare earth oxide powder is 1.0 wt%; The content of the reactive element powder is 5.0 wt%.

[0042] Among them, titanium borides include TiB whiskers and TiB2 particles, and chromium borides include CrB whiskers. The average diameter of TiB whiskers and CrB whiskers is less than 1 micrometer, and the aspect ratio is greater than 5.

[0043] The rare earth oxide particles are selected from cerium oxide and scandium oxide.

[0044] The thickness of the powder metallurgy intermediate layer is 0.1mm-2.0mm.

[0045] The nickel-based alloy matrix is ​​a nickel-based high-temperature alloy powder.

[0046] This application also proposes a method for preparing a nickel-based composite tube, comprising the following steps: S1. Prepare the outer metal plate and the inner metal plate separately, and clean and roughen the surfaces to be laminated; S2. Mix nickel-based alloy powder, rare earth oxide powder, and reactive element powder used for in-situ generation of reinforcing phase to obtain composite reinforced powder; S3. Spread the composite reinforcing powder on the surface of the inner or outer metal plate, and then cover it with another metal plate to form a three-layer flat preform of "metal plate-powder layer-metal plate". S4. The outer metal plate is covered on the inner metal plate covered with powder to form a plate-powder-plate preform, and then hot rolling composite is carried out under a protective atmosphere; the heating temperature is 980℃ and the total reduction rate is 30%-60%, which makes the powder layer dense and forms a strong metallurgical bond with the upper and lower metal plates to obtain a high-performance nickel-based composite plate. S5. The high-performance nickel-based composite plate is formed into a tube shape by JCO or UOE process and longitudinally welded to obtain a composite tube blank. The JCO forming adopts a multi-step progressive bending process, and the bending pressure in a single bending does not exceed 20% of the plate thickness. S6. The composite tube blank is heated to 1150℃ and held for 8 hours under a protective atmosphere to trigger the in-situ reaction of the reactive element powder with rare earth oxide particles as the core, generating a reinforcing phase, and finally achieving complete metallurgical bonding between the powder metallurgy intermediate layer and the inner and outer metal tubes, thus preparing a nickel-based composite tube.

[0047] In step S3, before spreading the composite reinforcing powder, a nickel-based transition layer with a thickness of 10-50 micrometers is prepared on the surface of the metal plate. The nickel-based transition layer is an electroplated nickel layer or a nickel-based alloy layer prepared by thermal spraying.

[0048] The reactive element powder is a combination of boron powder and chromium powder; the nickel-based alloy powder is a nickel-based high-temperature alloy powder.

[0049] Example 3 This invention provides a nickel-based composite tube, such as Figure 1 As shown, the nickel-based composite pipe is composed of an outer metal layer, a powder metallurgy intermediate layer, and an inner metal layer. The outer metal layer is carbon steel, and the inner metal layer is a corrosion-resistant nickel-based alloy plate. The powder metallurgy intermediate layer consists of a nickel-based alloy matrix and a reinforcing phase dispersed therein. The reinforcing phase is generated by in-situ reaction and is selected from titanium boride, chromium boride, and nickel-aluminum intermetallic compounds. More than 60% of the reinforcing phase is directly attached to the surface of rare earth oxide particles, which serve as heterogeneous nucleation centers.

[0050] The total weight of the raw materials for the powder metallurgy intermediate layer is used as the basis: The content of rare earth oxide powder is 1.5 wt%; The content of the reactive element powder is 8.0 wt%.

[0051] Among them, titanium borides include TiB whiskers and TiB2 particles, chromium borides include CrB whiskers, wherein the average diameter of TiB whiskers and CrB whiskers is less than 1 micrometer and the aspect ratio is greater than 5, and the nickel-aluminum intermetallic compound is Ni3Al intermetallic compound particles, all with an average size of less than 2 micrometers.

[0052] The rare earth oxide particles are selected from scandium oxide and erbium oxide.

[0053] The thickness of the powder metallurgy intermediate layer is 0.1mm-2.0mm.

[0054] The nickel-based alloy matrix is ​​nickel-chromium-aluminum alloy powder.

[0055] This application also proposes a method for preparing a nickel-based composite tube, comprising the following steps: S1. Prepare the outer metal plate and the inner metal plate separately, and clean and roughen the surfaces to be laminated; S2. Mix nickel-based alloy powder, rare earth oxide powder, and reactive element powder used for in-situ generation of reinforcing phase to obtain composite reinforced powder; S3. Spread the composite reinforcing powder on the surface of the inner or outer metal plate, and then cover it with another metal plate to form a three-layer flat preform of "metal plate-powder layer-metal plate". S4. The outer metal plate is covered on the inner metal plate covered with powder to form a plate-powder-plate preform, and then hot-rolled composite under a protective atmosphere; the heating temperature is 1050℃ and the total reduction rate is 30%-60%, which densifies the powder layer and forms a strong metallurgical bond with the upper and lower metal plates to obtain a high-performance nickel-based composite plate. S5. The high-performance nickel-based composite plate is formed into a tube shape by JCO or UOE process and longitudinally welded to obtain a composite tube blank. The JCO forming adopts a multi-step progressive bending process, and the bending pressure in a single bending does not exceed 20% of the plate thickness. S6. The composite tube blank is heated to 1200℃ and held for 8 hours under a protective atmosphere to trigger the in-situ reaction of the reactive element powder with rare earth oxide particles as the core, generating a reinforcing phase, and finally achieving complete metallurgical bonding between the powder metallurgy intermediate layer and the inner and outer metal tubes, thus preparing a nickel-based composite tube.

[0056] In step S3, before spreading the composite reinforcing powder, a nickel-based transition layer with a thickness of 10-50 micrometers is prepared on the surface of the metal plate. The nickel-based transition layer is an electroplated nickel layer or a nickel-based alloy layer prepared by thermal spraying.

[0057] The reactive element powder is aluminum powder; the nickel-based alloy powder is nickel-chromium-aluminum alloy powder.

[0058] Example 4 This invention provides a nickel-based composite tube, such as Figure 1 As shown, the nickel-based composite pipe is composed of an outer metal layer, a powder metallurgy intermediate layer, and an inner metal layer. The outer metal layer is carbon steel, and the inner metal layer is austenitic stainless steel; The powder metallurgy intermediate layer consists of a nickel-based alloy matrix and a reinforcing phase dispersed therein. The reinforcing phase is generated by in-situ reaction and is selected from at least one of chromium boride and nickel-aluminum intermetallic compounds. More than 60% of the reinforcing phase is directly attached to the surface of rare earth oxide particles that serve as heterogeneous nucleation centers.

[0059] The total weight of the raw materials for the powder metallurgy intermediate layer is used as the basis: The content of rare earth oxide powder is 2.2 wt%; The content of the reactive element powder is 11.0 wt%.

[0060] Among them, chromium borides include CrB whiskers, wherein the average diameter of CrB whiskers is less than 1 micrometer and the aspect ratio is greater than 5, and nickel aluminum intermetallic compounds are NiAl intermetallic compound particles, all with an average size of less than 2 micrometers.

[0061] The rare earth oxide particles are selected from at least two of yttrium oxide and erbium oxide.

[0062] The thickness of the powder metallurgy intermediate layer is 0.1mm-2.0mm.

[0063] The nickel-based alloy matrix is ​​nickel-chromium alloy powder, nickel-chromium-aluminum alloy powder, or nickel-based high-temperature alloy powder.

[0064] This application also proposes a method for preparing a nickel-based composite tube, comprising the following steps: S1. Prepare the outer metal plate and the inner metal plate separately, and clean and roughen the surfaces to be laminated; S2. Mix nickel-based alloy powder, rare earth oxide powder, and reactive element powder used for in-situ generation of reinforcing phase to obtain composite reinforced powder; S3. Spread the composite reinforcing powder on the surface of the inner or outer metal plate, and then cover it with another metal plate to form a three-layer flat preform of "metal plate-powder layer-metal plate". S4. The outer metal plate is covered on the inner metal plate covered with powder to form a plate-powder-plate preform, and then hot-rolled composite under a protective atmosphere; the heating temperature is 1110℃ and the total reduction rate is 30%-60%, which densifies the powder layer and forms a strong metallurgical bond with the upper and lower metal plates to obtain a high-performance nickel-based composite plate. S5. The high-performance nickel-based composite plate is formed into a tube shape by JCO or UOE process and longitudinally welded to obtain a composite tube blank. The JCO forming adopts a multi-step progressive bending process, and the bending pressure in a single bending does not exceed 20% of the plate thickness. S6. The composite tube blank is heated to 1200℃ and held for 8 hours under a protective atmosphere to trigger the in-situ reaction of the reactive element powder with rare earth oxide particles as the core, generating a reinforcing phase, and finally achieving complete metallurgical bonding between the powder metallurgy intermediate layer and the inner and outer metal tubes, thus preparing a nickel-based composite tube.

[0065] In step S3, before spreading the composite reinforcing powder, a nickel-based transition layer with a thickness of 10-50 micrometers is prepared on the surface of the metal plate. The nickel-based transition layer is an electroplated nickel layer or a nickel-based alloy layer prepared by thermal spraying.

[0066] The reactive element powder is a combination of boron powder and chromium powder; the nickel-based alloy powder is a nickel-chromium-aluminum alloy powder.

[0067] Example 5 This invention provides a nickel-based composite tube, such as Figure 1 As shown, the nickel-based composite pipe is composed of an outer metal layer, a powder metallurgy intermediate layer, and an inner metal layer. The outer metal layer is made of low-alloy steel plate, and the inner metal layer is made of corrosion-resistant nickel-based alloy plate; The powder metallurgy intermediate layer consists of a nickel-based alloy matrix and a reinforcing phase dispersed therein. The reinforcing phase is generated by in-situ reaction and is selected from titanium borides and nickel-aluminum intermetallic compounds. More than 60% of the reinforcing phase is directly attached to the surface of rare earth oxide particles that serve as heterogeneous nucleation centers.

[0068] The total weight of the raw materials for the powder metallurgy intermediate layer is used as the basis: The content of rare earth oxide powder is 3.0 wt%; The content of the reactive element powder is 15.0 wt%.

[0069] Among them, the titanium borides include TiB whiskers and TiB2 particles. The average diameter of the TiB whiskers is less than 1 micrometer and the aspect ratio is greater than 5. The nickel-aluminum intermetallic compound is NiAl intermetallic compound particles, and the average size is less than 2 micrometers.

[0070] The rare earth oxide particles are selected from at least two of cerium oxide and erbium oxide.

[0071] The thickness of the powder metallurgy intermediate layer is 0.1mm-2.0mm.

[0072] The nickel-based alloy matrix is ​​nickel-chromium alloy powder.

[0073] This application also proposes a method for preparing a nickel-based composite tube, comprising the following steps: S1. Prepare the outer metal plate and the inner metal plate separately, and clean and roughen the surfaces to be laminated; S2. Mix nickel-based alloy powder, rare earth oxide powder, and reactive element powder used for in-situ generation of reinforcing phase to obtain composite reinforced powder; S3. Spread the composite reinforcing powder on the surface of the inner or outer metal plate, and then cover it with another metal plate to form a three-layer flat preform of "metal plate-powder layer-metal plate". S4. The outer metal plate is covered on the inner metal plate covered with powder to form a plate-powder-plate preform, and then hot rolling composite is carried out under a protective atmosphere; the heating temperature is 1150℃ and the total reduction rate is 30%-60%, which makes the powder layer dense and forms a strong metallurgical bond with the upper and lower metal plates to obtain a high-performance nickel-based composite plate. S5. The high-performance nickel-based composite plate is formed into a tube shape by JCO or UOE process and longitudinally welded to obtain a composite tube blank. The JCO forming adopts a multi-step progressive bending process, and the bending pressure in a single bending does not exceed 20% of the plate thickness. S6. The composite tube blank is heated to 1250℃ and held for 8 hours under a protective atmosphere to trigger the in-situ reaction of the reactive element powder with rare earth oxide particles as the core, generating a reinforcing phase, and finally achieving complete metallurgical bonding between the powder metallurgy intermediate layer and the inner and outer metal tubes, thus preparing a nickel-based composite tube.

[0074] In step S3, before spreading the composite reinforcing powder, a nickel-based transition layer with a thickness of 10-50 micrometers is prepared on the surface of the metal plate. The nickel-based transition layer is an electroplated nickel layer or a nickel-based alloy layer prepared by thermal spraying.

[0075] The reactive element powder is a combination of boron powder and titanium powder; the nickel-based alloy powder is a nickel-chromium alloy powder.

[0076] Comparative Example 1 A nickel-based composite tube differs from Example 1 only in that rare earth oxide powder is not added to the raw materials of the powder metallurgy intermediate layer. The weight percentage of rare earth oxides in the total raw material weight is supplemented by nickel-based alloy powder; the remaining materials and preparation methods are the same as in Example 1.

[0077] Comparative Example 2 A nickel-based composite tube differs from Example 1 only in that the raw materials for the powder metallurgy intermediate layer do not contain reactive element powders for in-situ generation of reinforcing phases. The weight percentage of reactive element powders in the total weight of the raw materials is made up by nickel-based alloy powders, while the remaining materials and preparation methods are the same as in Example 1.

[0078] Comparative Example 3 A nickel-based composite tube differs from Example 1 only in that the JCO forming process in step S5 is omitted. Instead, the high-performance nickel-based composite plate obtained in step S4 is directly formed into a tube by conventional UO or roll bending forming processes and longitudinally welded. Step S6 is then performed. The remaining steps and materials are the same as in Example 1.

[0079] Performance testing To verify the excellent performance of the nickel-based composite tube of the present invention, the materials obtained in Examples 1-5 and Comparative Examples 1-3 were subjected to performance tests, including room temperature mechanical properties, high temperature oxidation resistance and microstructure stability tests. The test results are shown in Table 1 below.

[0080] Table 1 Performance Tests

[0081] As shown in Table 1, the nanoindentation hardness of Examples 1-5 is significantly higher than that of Comparative Examples 1-3. Example 5, with its 15.0 wt% reactive element content and nickel-chromium alloy matrix design, achieved the highest hardness of 10.8 GPa. The multi-element reinforcing elements in Example 2 also achieved a high hardness of 10.1 GPa. The comparative examples show that rare earth oxides (which reduced hardness by 27%), the in-situ reinforcing phase formed by the reactive elements (which reduced hardness by 41%), and the JCO forming process (which reduced hardness by 12%) all play a key role in material strengthening. These three factors together ensure the excellent hardness level of 8.5-10.8 GPa in the Example group. Example 3, which contains only a moderate reactive element content, has a relatively low hardness (7.8 GPa).

[0082] In terms of antioxidant performance, the oxidation weight gain of the example groups under 900°C / 100h conditions was 1.9-3.8 mg / cm², which is in the excellent range of nickel-based superalloys. Among them, Example 3 showed the best performance (2.0 mg / cm²) through the design of rare earth combination and nickel-chromium-aluminum alloy matrix. The comparative examples further confirmed that rare earth oxides can significantly reduce the oxidation rate (oxidation weight gain increased by 270% without rare earth), and in-situ reinforcing phase can improve microstructure and enhance antioxidant performance (oxidation weight gain increased by 209% without reactive elements). The JCO process has a particularly prominent effect on the optimization of interface bonding and antioxidant performance (oxidation weight gain increased by 322% without this process). However, Example 2 has a relatively high oxidation weight gain (3.8 mg / cm²) due to the complex high-temperature oxidation behavior of multiple elements.

[0083] like Figures 2-6The SEM images shown indicate that the nickel-based composite tubes prepared in Examples 1-5 have a uniform and dense microstructure in their powder metallurgy intermediate layer, and the reinforcing phases (including TiB whiskers, TiB2 particles, CrB whiskers, and intermetallic compound particles such as Ni3Al / NiAl) are finely and dispersedly distributed in the nickel-based alloy matrix.

[0084] To quantitatively confirm its unique "heterogeneous nucleation" interface structure, transmission electron microscopy (TEM) and accompanying energy dispersive spectroscopy (EDS) line / area scanning analyses were performed on selected regions. Figure 10 As shown in the high-resolution TEM image, two distinct atomic lattice fringes are clearly visible within the field of view. One corresponds to the lattice of the rare-earth oxide particles, while the other corresponds to the lattice of the reinforcing phase epitaxially grown on their surface. The atoms at the interface between the two phases are coherently arranged, forming a direct crystallographic orientation relationship. This provides conclusive atomic-scale evidence for the core structural feature that "more than 60% of the reinforcing phase is directly attached to the surface of the rare-earth oxide particles."

[0085] like Figure 11 As shown, significant peak values ​​of rare earth elements (such as Y and Ce) are observed at the phase interface region between the reinforcing phase and the nickel-based alloy matrix. These peak values ​​are several times higher than those within the adjacent matrix. This directly demonstrates that rare earth oxide particles are not randomly dispersed, but rather preferentially and selectively distributed at the interface between the reinforcing phase and the matrix, thus successfully achieving interfacial enrichment.

[0086] This unique interface enrichment structure, like a "nanorhine," plays a key role in two ways: Interface strengthening and pinning effect: High-hardness rare earth oxide particles enriched at the interface can effectively hinder the slip and proliferation of dislocations at the interface, thereby greatly strengthening the interfacial bonding between the reinforcing phase and the matrix, and significantly improving the room temperature strength and nanoindentation hardness of the material through a strong pinning effect.

[0087] Interface stability and diffusion barrier: At high temperatures, these thermodynamically stable rare earth oxide particles greatly stabilize the interface structure and act as a physical barrier, significantly inhibiting the rapid diffusion of oxygen atoms and other alloying elements along the reinforcing phase / matrix interface. This effectively delays the precipitation of harmful phases and the premature nucleation and spalling of the oxide film, thereby endowing the material with excellent high-temperature oxidation resistance and microstructural thermal stability.

[0088] In contrast, such as Figure 7 As shown in Comparative Example 1, the reinforcing phase directly nucleates and grows in the nickel matrix, with a clear and straight interface with the matrix, without any rare earth element enrichment, completely losing the interface strengthening and stabilizing effect of the aforementioned "nanorhines"; Figure 8As shown in Comparative Example 2, the rare earth oxide particles are isolated and randomly distributed in the nickel-based alloy matrix, failing to bond with any reinforcing phase, and thus unable to exert their key interface engineering effect; Figure 9 As shown, microcracks and interface damage caused by severe plastic deformation can be observed in the microstructure of Comparative Example 3. Although its composition is the same as that of Example 1, the stress concentration at the defects destroys the integrity of the structure and becomes a rapid channel in the high-temperature oxidation process. This explains the reason for the sharp deterioration of the antioxidant performance of Comparative Example 3 from a microscopic mechanism.

[0089] To further verify the comprehensive mechanical properties of the material of the present invention, room temperature tensile tests and high temperature creep strength tests were conducted. The samples of Examples 1-5 and Comparative Examples 1-3 were tested, as shown in Table 2 below.

[0090] Table 2 Comprehensive Mechanical Properties

[0091] As shown in Table 2, Examples 1-5 exhibit excellent comprehensive mechanical properties and good designability. Their tensile strength and yield strength fall within the reasonable ranges of 830-940 MPa and 620-765 MPa, respectively, while their elongation after fracture reaches 10.8-16.8%, demonstrating a good strength-toughness balance. The yield strength ratio of 0.73-0.81 also conforms to the conventional range for nickel-based alloys, indicating that the material still has continuous work hardening capability after yielding. Among them, Examples 2 (920 MPa, 12.5%) and 5 (940 MPa, 10.8%) achieve high strength characteristics close to 1 GPa due to their high reinforcing phase and rare earth content; Example 3 (830 MPa, 16.8%) achieves high plasticity design while maintaining a higher strength than the comparative example; Examples 1 (850 MPa, 15.0%) and 4 (870 MPa, 13.7%) achieve the best balance between strength and plasticity, confirming that materials with different performance focuses can be customized according to service requirements through composition adjustment. The overall mechanical properties of all embodiments are far superior to those of the comparative examples, further verifying the core role of key technical elements: rare earth oxides and in-situ reinforcing phases are the fundamental factors for improving mechanical properties.

[0092] Comparative Example 1 (600 MPa, 9.0%) without rare earth oxides had low strengthening efficiency due to poor nucleation and distribution of the reinforcing phase. Comparative Example 2 (550 MPa, 10.5%) without in-situ reinforcing phase had the worst performance due to the lack of a load-bearing core carrier. Rare earth oxides, by optimizing the nucleation and distribution of the reinforcing phase, fully exerted their strengthening potential. The JCO molding process is the key to ensuring the ductility and service reliability of the material. Although the tensile strength (610 MPa) of Comparative Example 3 without this process was slightly higher than that of Comparative Example 1, its elongation after fracture was only 5.4%, exhibiting low-stress brittle fracture characteristics. Moreover, it had the worst high-temperature oxidation resistance (9.7 mg / cm²). The root cause is that conventional molding processes introduce microcracks and interface debonding damage into the material and composite interface. These damages can become crack sources during room temperature tensile testing and accelerate oxygen diffusion at high temperatures, leading to oxidation failure.

[0093] It should be noted that, to further verify the service potential of the material of this invention under extreme working conditions, high-temperature creep strength tests were conducted on typical samples under harsh conditions of 800°C and 250MPa. The test results show that the material of this invention exhibits excellent high-temperature load-bearing capacity. The creep life of all embodiments significantly exceeds 100 hours, with Embodiment 1 having a creep life greater than 200 hours and Embodiment 3 even exceeding 300 hours, exhibiting ductile fracture characteristics, with uniform fracture surfaces and deep and uniform dimples visible at the microscopic level, fully demonstrating that these materials have the potential for long-term safe service under high temperature and high pressure environments. Embodiment 2 has a creep life of 185 hours, and Embodiment 4 has a creep life of 165 hours, both exhibiting ductile-brittle mixed fracture, showing balanced high-temperature performance. Embodiment 5 has a relatively short creep life of 120 hours, exhibiting brittle fracture, with a straight fracture surface that extends along the reinforcing phase / matrix interface. This phenomenon is related to its highest reinforcing phase content and relatively low plasticity. Under extremely high stress, the high volume fraction of hard phase easily exacerbates stress concentration and becomes a preferred crack initiation point. However, even so, its performance is still far superior to all comparative embodiments.

[0094] The performance differences of each embodiment are directly related to the composition, structure and process. The reason why Example 3 can achieve the longest service life is due to its best antioxidant properties (2.0 mg / cm²) and the highest room temperature plasticity (16.8%). The addition of Al not only forms a protective oxide film, but also simultaneously improves the high temperature strength and toughness of the matrix, which significantly enhances its creep resistance and damage resistance.

[0095] The comparative data, in turn, confirm the core technical advantages of this invention: Comparative Example 1 without rare earth and Comparative Example 2 without reinforcing phase both had a creep life of less than 50 hours, at 42 hours and 28 hours respectively. The former exhibited brittle fracture with the fracture surface cracking along the coarse reinforcing phase aggregation area, while the latter showed early creep fracture with the fracture surface exhibiting intergranular cracking characteristics. This indicates that without either rare earth oxide or any phase of the in-situ reinforcing phase, the high-temperature strength and microstructure stability of the material would completely collapse. Comparative Example 3 without the JCO process had the shortest creep life, at only 18 hours, which was early brittle fracture. Fracture surface analysis clearly revealed that the failure originated from the damage introduced by the molding process. This result proves that under the harsh conditions of high temperature and high stress coupling, microscopic defects caused by inappropriate molding processes are the root cause of catastrophic early failure of components.

[0096] This application provides a nickel-based composite tube in which yttrium oxide is pre-mixed with at least two rare earth oxides such as cerium oxide / scandium oxide / erbium oxide in a powder system. Yttrium oxide acts as a thermodynamically stable inert heterogeneous nucleation core, providing fixed nucleation sites for reinforcing phases such as titanium boride, chromium boride, and nickel-aluminum intermetallic compounds. The active rare earth oxides segregate at the reinforcing phase-matrix interface, reducing interfacial energy and increasing nucleation sites. Simultaneously, yttrium oxide acts as a static Zener pinning point, inhibiting grain coarsening and reinforcing phase coarsening at high temperatures, ensuring creep resistance. In terms of performance and structural stability, active rare earth elements dynamically purify the interface and repair micro-damage. Combined with a nickel-based matrix containing multiple reinforcing elements such as W and Mo, the composite pipe can operate stably under extreme high-temperature, high-pressure, and highly corrosive environments. The load transfer effect of high aspect ratio whiskers, the Orowan reinforcement of dispersed particles, the crack deflection of oxides, and the interfacial chemical bonding effect achieve a breakthrough in performance, with an interfacial shear strength >150MPa, a room temperature yield strength ≥400MPa, and excellent toughness, overcoming the bottleneck of balancing strength and toughness. Furthermore, this invention designs three differentiated matrices: nickel-chromium alloy (general-purpose), nickel-chromium-aluminum alloy (high-strength), and nickel-based high-temperature alloy (extreme operating condition), adapting to different scenario requirements. Compared to overall corrosion-resistant alloy pipes, the cost is reduced by 40-60%. Through hot-rolling composite processes combined with an optional nickel-based transition layer, the traditional abrupt interface is transformed into a functionally graded structure, completely eliminating stress concentration and solving the failure risk of easy interface peeling and cracking. Ultimately, a balance between comprehensive performance, economy, and reliability is achieved.

[0097] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A nickel-based composite pipe, characterized in that, The nickel-based composite tube is composed of an outer metal layer, a powder metallurgy intermediate layer, and an inner metal layer, wherein... The outer metal layer is carbon steel or low alloy steel plate, and the inner metal layer is austenitic stainless steel, duplex stainless steel or corrosion-resistant nickel-based alloy plate. The powder metallurgy intermediate layer is composed of a nickel-based alloy matrix and a reinforcing phase dispersed therein. The reinforcing phase is generated by in-situ reaction and is selected from at least one of titanium boride, chromium boride, and nickel-aluminum intermetallic compounds. More than 60% of the reinforcing phase is directly attached to the surface of rare earth oxide particles that serve as heterogeneous nucleation centers.

2. The nickel-based composite pipe according to claim 1, characterized in that, Based on the total weight of the raw materials for the powder metallurgy intermediate layer: The content of the rare earth oxide powder is 0.05wt%-3.0wt%; The content of the reactive element powder is 2.0wt%-15.0wt%.

3. The nickel-based composite pipe according to claim 1, characterized in that, The titanium boride includes TiB whiskers and TiB2 particles, and the chromium boride includes CrB whiskers, wherein the average diameter of the TiB whiskers and the CrB whiskers is less than 1 micrometer and the aspect ratio is greater than 5.

4. The nickel-based composite pipe according to claim 1, characterized in that, The nickel-aluminum intermetallic compound is Ni3Al or NiAl intermetallic compound particles, with an average size of less than 2 micrometers.

5. A nickel-based composite pipe according to claim 1, characterized in that, The rare earth oxide particles are selected from at least two of yttrium oxide, cerium oxide, scandium oxide, and erbium oxide.

6. A nickel-based composite pipe according to claim 1, characterized in that, The thickness of the powder metallurgy intermediate layer is 0.1mm-2.0mm.

7. A nickel-based composite pipe according to claim 1, characterized in that, The nickel-based alloy matrix is ​​nickel-chromium alloy powder, nickel-chromium-aluminum alloy powder, or nickel-based high-temperature alloy powder.

8. A method for preparing a nickel-based composite tube according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Prepare the outer metal plate and the inner metal plate separately, and clean and roughen the surfaces to be laminated; S2. Mix nickel-based alloy powder, rare earth oxide powder, and reactive element powder used for in-situ generation of reinforcing phase to obtain composite reinforced powder; S3. Spread the composite reinforcing powder on the surface of the inner metal plate or the outer metal plate, and then cover it with another metal plate to form a three-layer flat preform of "metal plate-powder layer-metal plate"; S4. The outer metal plate is covered on the inner metal plate covered with powder to form a plate-powder-plate preform, and then hot rolling composite is performed under a protective atmosphere; the heating temperature is 900-1150℃, and the total reduction rate is 30%-60%, so that the powder layer is densified and forms a strong metallurgical bond with the upper and lower metal plates to obtain a high-performance nickel-based composite plate. S5. The high-performance nickel-based composite plate is formed into a tube shape by JCO or UOE process and longitudinally welded to obtain a composite tube blank. The JCO forming adopts a multi-step progressive bending process, and the bending pressure in a single bending does not exceed 20% of the plate thickness. S6. The composite tube blank is heated to 1100-1250℃ under a protective atmosphere and held for 1-8 hours to trigger the in-situ reaction of the reactive element powder with the rare earth oxide particles as the core, generating the reinforcing phase, and finally achieving complete metallurgical bonding between the powder metallurgy intermediate layer and the inner and outer metal tubes, thus preparing the nickel-based composite tube.

9. The method for preparing a nickel-based composite tube according to claim 8, characterized in that, In step S3, before spreading the composite reinforcing powder, a nickel-based transition layer with a thickness of 10-50 micrometers is prepared on the surface of the metal plate, wherein the nickel-based transition layer is an electroplated nickel layer or a nickel-based alloy layer prepared by thermal spraying.

10. The method for preparing a nickel-based composite tube according to claim 8, characterized in that, The reactive element powder is a combination of boron powder and titanium powder, a combination of boron powder and chromium powder, or aluminum powder; the nickel-based alloy powder is nickel-chromium alloy powder, nickel-chromium-aluminum alloy powder, or nickel-based high-temperature alloy powder.

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