Nickel-tungsten alloy with quadruple compound gradient nanostructure and preparation method of nickel-tungsten alloy

Abstract

The invention provides a nickel-tungsten alloy with a quadruple compound gradient nanostructure and a preparation method of the nickel-tungsten alloy, and relates to the technical field of nickel-tungsten alloy preparation. The core part of the nickel-tungsten alloy is composed of a nanophase-fine grain structure, and the surface layer of the nickel-tungsten alloy is composed of a quadruple complex gradient structure of gradient nanophase, gradient nanocrystal grains, gradient nano twin crystals and gradient dislocation. During preparation, micron-sized uniform fine grains on the surface layer of the nickel-tungsten alloy in a forged state or a solid solution state after forging are converted into gradient nanocrystals by adopting a surface nanocrystallization technology, and gradient nano twin crystals and gradient dislocations are formed in the gradient crystal grains, so that a triple compound gradient nanostructure is obtained; and then aging treatment is conducted on the nickel-tungsten alloy with the triple composite gradient nanostructure, a nanophase is separated out in a gradient mode from the outside to the inside, the nickel-tungsten alloy with the quadruple composite gradient nanostructure is prepared, and the core of the nickel-tungsten alloy is subjected to aging nano-separation to obtain a nanophase-fine grain structure. The nickel-tungsten alloy provided by the invention has excellent static / dynamic comprehensive performance and breakthrough surface layer performance.

Description

Technical Field

[0001] The present invention relates to the technical field of nickel-tungsten alloy preparation, and particularly to a nickel-tungsten alloy with a quadruple composite gradient nanostructure and a preparation method thereof. Background Art

[0002] Nickel-tungsten alloys with excellent static / dynamic comprehensive properties are one of the key basic materials in the fields of construction machinery, major national defense equipment, aerospace equipment, penetration warhead equipment, etc. The service environment is generally an extreme environment of high temperature, high pressure and high strain rate, and the material has to undergo extremely complex coupling effects during deformation and service. Among them, for the projectile material of the kinetic energy penetration warhead, the nickel-tungsten alloy adopts a fully solid solution structure. A large amount of tungsten is dissolved in the solid solution, which can improve the strength and density of the material; its face-centered cubic structure has multiple slip systems, and a large number of slip bands and twins will be generated during the deformation process, enabling the material to undergo cooperative deformation and avoiding stress concentration, which solves the problem of easy adiabatic shear failure; in addition, the alloy can also precipitate fine and dispersed second phases through aging treatment to produce second-phase strengthening and further improve the strength. However, with the continuous increase in the defense strength of the destroyed target, the kinetic energy penetration warhead is also developing towards higher speed and larger equivalent. As the projectile material, the strength of the nickel-tungsten alloy still needs to be improved urgently. It is necessary to greatly improve the surface strength, hardness, wear resistance and structural stability without losing other excellent properties such as plastic toughness and stable dynamic strain hardening rate. However, in terms of the strengthening and toughening of the alloy, traditional strengthening techniques often lead to a decrease in plasticity while increasing the strength of the alloy. This dilemma of the strength-toughness contradiction relationship has become an important problem restricting the new breakthrough improvement of the static / dynamic comprehensive properties of nickel-tungsten alloy products.

[0003] According to the Hall-Petch formula, the strength of polycrystalline metal materials increases with the decrease of grain size [Reference 1: Petch N. The ductile–brittle transition in the fracture of α–iron: I. Philosophical Magazine, 1958, A3: 1089–1097.]. When the grain size > 1 μm, grain refinement improves the material strength without reducing plasticity; when the grain size is uniformly refined to the sub-micron (< 1 μm) or even nano-scale (< 100 nm), the strength increases significantly. Compared with traditional coarse-grained (> 1 μm) materials, smaller-sized nanocrystals have a large number of grain boundaries, resulting in higher strength and hardness, enhanced physical and tribological properties. However, due to the decrease of grain size, dislocation slip is inhibited by extremely small grains, and dislocations cannot be fully accumulated inside the grains. Grain boundary sliding or diffusion creep is insufficient to accommodate plastic strain at ambient temperature [Reference 2: Fang T.H., Li W.L., Tao N.R., et al. Revealing Extraordinary Intrinsic Tensile Plasticity in Gradient Nano-Grained Copper. Science, 2011, 331(6024): 1587-1590.]. In addition, there are a large number of grain boundaries and dislocations and other defects inside nanostructured materials. Because the energy at the defect sites is relatively high, the material is in a thermodynamically unstable state as a whole and is prone to grain coarsening [Reference 3: Riano J.S., Hodge A.M.. Exploring the microstructural evolution of Hf-Ti: From nanometallic multilayers to nanostructures. Scripta Materialia, 2018, 142: 55-60.]. The nanocrystalline structure tends to develop in the direction of eliminating interfaces to reduce the overall energy and transform into a metastable or stable state [Reference 4: Zhang Lixuan. Research on the Microstructural Evolution and Thermal Stability of Nanocrystalline Nickel-Based Alloys. Nanjing University of Science and Technology, 2021.]. Therefore, while improving the strength, it will cause serious plastic loss, and still cannot escape the law of the decrease of plastic toughness, the disappearance of strain hardening ability, and the reduction of structural stability caused by the increase of strength.[Reference 5: Lu K. Stabilizing nanostructures in metals using grain and twin boundary architectures. Nature Reviews Materials, 2016, 16019. Reference 6: Wei B, Wu W, Xie D, et al. Strength, plasticity, thermal stability and strain rate sensitivity of nanograined nickel with amorphous ceramic grain boundaries. Acta Materialia, 2021, 212: 116918.]

[0004] In view of the above background, to meet the requirements of high-end strong, tough, wear-resistant, and structurally stable nickel-tungsten alloy structural parts and components in various industrial and national defense application fields, it is necessary to make breakthroughs in the preparation process and technology to provide technical support for the development of new nickel-tungsten alloy products with high strength, high plastic toughness, excellent dynamic performance, and structural stability. Summary of the Invention

[0005] To solve the above technical problems existing in the prior art and develop new nickel-tungsten alloy products with high strength, high plastic toughness, and excellent dynamic performance, the embodiments of the present invention provide a nickel-tungsten alloy with a quadruple composite gradient nanostructure and a preparation method thereof. By designing and preparing a core with a nano-phase-fine grain structure and a surface layer composed of a quadruple composite gradient structure of gradient nano-phase, gradient nano-grains, gradient nano-twins, and gradient dislocations in the nickel-tungsten alloy product, the nickel-tungsten alloy product has excellent static / dynamic comprehensive properties (high strength and toughness, high dynamic strength, high structural stability) and breakthrough (ultra-strong, ultra-hard, highly tough and wear-resistant) surface layer properties. The technical solutions are as follows:

[0006] A nickel-tungsten alloy with a quadruple composite gradient nanostructure, the nickel-tungsten alloy is divided into a core and a surface layer, the core is composed of a nano-phase-fine grain structure, and the surface layer is composed of a quadruple composite gradient structure of gradient nano-phase, gradient nano-grains, gradient nano-twins, and gradient dislocations.

[0007] The nano-phase-fine grain structure is specifically: nano-phases are diffusely distributed inside micron-sized fine grains.

[0008] The thickness of the surface layer is the depth at which the gradient dislocations spread from the surface of the surface layer towards the core;

[0009] A gradient nanophase is formed at the surface of the surface layer at ~A mm, a gradient nanograin is formed at ~B μm from the surface of the surface layer, a gradient nanotwin is formed at ~C μm from the surface of the surface layer, and a gradient dislocation is formed at ~D mm from the surface of the surface layer;

[0010] Among them, A = D ≤ 1, B ≤ 500, C ≤ 700;

[0011] The core is the area with a depth greater than A mm from the surface of the surface layer inward.

[0012] The preparation method of the above nickel-tungsten alloy with a quadruple composite gradient nanostructure includes the following steps:

[0013] S1. Transform the micron-scale uniform fine grains in the area of ~B μm on the surface of the nickel-tungsten alloy forging blank into gradient nanograins, form gradient nanotwins in the area of ~C μm on the surface, and form gradient dislocations in the area of ~D mm on the surface, so that the grains, twins and dislocations are all gradient-distributed from the surface to the inside, and a triple composite gradient nanostructure is obtained;

[0014] S2. Perform aging treatment on the nickel-tungsten alloy with a triple composite gradient nanostructure obtained in step S1 at 650 - 900 °C for 1 - 7 h. Nanophases are precipitated in a gradient from the surface to the inside in the area of ~A mm on the surface of the surface layer, and a nanophase-fine grain structure is obtained by nanophase precipitation in the core, and a nickel-tungsten alloy with a quadruple composite gradient nanostructure is prepared.

[0015] In step S1, the nickel-tungsten alloy forging blank is first solution-treated at 900 - 1100 °C for 0.5 - 2 h to obtain a supersaturated solid solution nickel-tungsten alloy with a uniform fine grain structure. Then, after being treated by steps S1 and S2, the plasticity of the obtained nickel-tungsten alloy is higher than that of the nickel-tungsten alloy without solution treatment, and the strength is lower than that of the nickel-tungsten alloy without solution treatment.

[0016] The cooling method for the solution treatment is oil cooling, and the cooling method for the aging treatment in step S2 is air cooling.

[0017] The average grain size of the nickel-tungsten alloy forging blank in step S1 is less than 15 μm.

[0018] In step S1, the surface mechanical nanocrystallization treatment technology is used to transform the micron-scale uniform fine grains on the surface layer into gradient nanograins, and gradient nanotwins and gradient dislocations are formed inside the gradient nanograins and in the direction from the surface layer to the core;

[0019] The surface mechanical nanocrystallization treatment technology is one of surface mechanical grinding treatment method, cam rolling, ultrasonic shot peening, pneumatic shot peening, laser irradiation, laser remelting, laser shot peening, and supersonic particle bombardment.

[0020] The parameters of the ultrasonic shot peening process are set as follows: 20 - 100 bearing steel shots or tungsten carbide shots with a diameter of 2 - 4 mm, the working distance (the distance from the material to the ultrasonic vibration surface) is 8 - 15 mm, the shot peening amplitude is set at 15 - 50 μm, and the shot peening duration is 2 - 15 min.

[0021] The nickel-tungsten alloy is Ni-W-Co-Ta alloy. The chemical composition of the nickel-tungsten alloy by mass percentage is: Ni 47 - 64.8%, W 35 - 40%, Co 0.1 - 8%, Ta 0.1 - 5%.

[0022] The beneficial effects brought by the technical solutions provided in the embodiments of the present invention at least include:

[0023] 1. The nickel-tungsten alloy with a quadruple composite gradient nanostructure provided by the present invention is prepared by designing a core with a nano-phase and fine-grained structure and a surface layer with a quadruple composite gradient nanostructure composed of gradient nano-phases, gradient nano-grains, gradient nano-twins, and gradient dislocations in the nickel-tungsten alloy product. On the one hand, by utilizing the synergistic strengthening and toughening effect of the nano-phase and micron-scale fine grains in the core structure, the comprehensive strength and toughness of the core of the nickel-tungsten alloy are improved; on the other hand, by utilizing the efficient synergistic strengthening effect of the gradient nano-phases, gradient nano-grains, gradient nano-twins, and gradient dislocations in the surface layer structure, and because the gradient structure has a hetero-deformation-induced hardening effect, the strength and wear resistance of the surface layer of the nickel-tungsten alloy can be greatly improved. Through the combined action of the two, excellent static / dynamic comprehensive properties (high strength and toughness, high dynamic strength, high structural stability) and breakthrough (super high wear resistance) surface layer properties are obtained.

[0024] 2. The preparation method of the nickel-tungsten alloy with a quadruple composite gradient nanostructure provided by the present invention is realized through comprehensive technical means such as solution treatment, surface nanocrystallization, and aging treatment. These related technologies have made great progress in recent years and have strong applicability, providing a practical new approach for the development of high-end strong, tough, wear-resistant, and structurally stable nickel-tungsten alloy products such as warhead projectile materials, construction machinery materials, and aerospace materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 It is a schematic flow chart of a preparation method of a nickel-tungsten alloy with a quadruple composite gradient nanostructure provided by an embodiment of the present invention;

[0027] Figure 2It is a photograph of the composite gradient nanostructured nickel-tungsten alloy sample after ultrasonic shot peening treatment in the embodiment of the present invention;

[0028] Figure 3 Taking the warhead projectile product as an example, it is a design schematic diagram of the composite gradient nanostructure on the nickel-tungsten alloy structural parts / components in the embodiment of the present invention.

[0029] Wherein: 1 - composite gradient nanostructured surface layer; 2 - nanoscale grains in the composite gradient nanostructured surface layer; 3 - nanoscale twins in the composite gradient nanostructured surface layer; 4 - nanophase in the composite gradient nanostructured surface layer; 5 - dislocations in the composite gradient nanostructured surface layer; 6 - nanophase-fine grain structure core; 7 - micron-sized grains in the nanophase-fine grain structure core; 8 - micron-sized twins in the nanophase-fine grain structure core; 9 - nanophase in the nanophase-fine grain structure core. Detailed implementation manners

[0030] The technical solutions in the present invention will be described below with reference to the accompanying drawings.

[0031] In the embodiments of the present invention, words such as "exemplarily", "for example", etc. are used to represent examples, illustrations or explanations. Any embodiment or design solution described as an "example" in the present invention should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Exactly speaking, the use of the word "example" is intended to present concepts in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one of the two can be selected.

[0032] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0033] The embodiments of the present invention provide a nickel-tungsten alloy with a quadruple composite gradient nanostructure and a preparation method thereof. As Figure 1 Shown in the flowchart of the preparation method of the nickel-tungsten alloy with a quadruple composite gradient nanostructure, this method may include the following steps:

[0034] S1. The nickel-tungsten alloy forging blank is subjected to solution treatment at 900 - 1100 °C for 0.5 - 2 h to obtain a supersaturated solid solution nickel-tungsten alloy with a uniform fine grain structure;

[0035] S2. The micron-sized uniform fine grains in the surface layer surface - B μm region of the supersaturated solid solution nickel-tungsten alloy with a uniform fine grain structure are transformed into gradient nanograins, and gradient nanoscale twins are formed in the surface layer surface - C μm region, and gradient dislocations are formed in the surface layer surface - D mm region, so that the grains, twins and dislocations are all gradient-distributed from the surface to the inside, and a triple composite gradient nanostructure is obtained;

[0036] S3. The nickel-tungsten alloy with a triple composite gradient nanostructure between 650 and 900 °C is subjected to aging treatment for 1 to 7 h. In the ~Amm region of the surface layer, nanophases precipitate in a gradient from the surface to the interior, and nanophase-fine grain structure is obtained by nanoprecipitation in the core, preparing a nickel-tungsten alloy with a quadruple composite gradient nanostructure.

[0037] In actual preparation, according to the process, the ranges of A and D are the same, not exceeding 1 mm, B does not exceed 500 μm, and C does not exceed 700 μm.

[0038] In step S1, solution treatment is carried out to eliminate the stress concentration left inside the material after forging and promote the re-dissolution of undissolved high-tungsten particles and the annihilation of dislocations, adjusting the alloy properties to be suitable for subsequent surface deformation treatment. This heat treatment will make the properties of the final product have an excellent strength-ductility matching relationship. If there is a practical need for higher strength of the product performance, this heat treatment can be optionally not carried out to obtain a final product with higher strength but reduced plasticity.

[0039] In step S2, the surface of the nickel-tungsten alloy with a uniform fine grain structure is subjected to severe surface plastic deformation (such as ultrasonic shot peening). The micron-scale uniform fine grains on the surface layer of the nickel-tungsten alloy are transformed into gradient nanocrystals. At the same time, due to the relatively low stacking fault energy of its face-centered cubic structure, the ultra-high strain rate caused by severe plastic deformation will also promote the formation of deformation twins in the gradient nanograins, and introduce a high density of dislocations (dislocation walls and dislocation cells are formed on the surface layer) and store a relatively high energy in the alloy, obtaining a triple composite gradient structure of gradient nanocrystals, gradient nanotwins, and gradient dislocations.

[0040] In step S3, the nickel-tungsten alloy with a triple composite gradient nanostructure is subjected to aging treatment. Combining the high energy generated by the gradient evolution of surface deformation, nanoscale Ni4W second-phase precipitates are induced in a gradient from the surface to the interior, preparing a nickel-tungsten alloy with a quadruple composite gradient nanostructure.

[0041] Therefore, the nickel-tungsten alloy obtained by the present invention is as Figure 3 shown, which is divided into a nanophase-fine grain structure core 6 and a composite gradient nanostructure surface layer 1.

[0042] Among them, the composite gradient nanostructure surface layer 1 includes nanoscale grains 2 in the composite gradient nanostructure surface layer, nanoscale twins 3 in the composite gradient nanostructure surface layer, nanophases 4 in the composite gradient nanostructure surface layer, and dislocations 5 in the composite gradient nanostructure surface layer; the nanophase-fine grain structure core 6 includes micron-scale grains 7 in the nanophase-fine grain structure core, micron-scale twins 8 in the nanophase-fine grain structure core, and nanophases 9 in the nanophase-fine grain structure core.

[0043] Taking the Ni-W-Co-Ta alloy projectile material for penetration warheads as an example, a high-strength and tough projectile core is obtained through the synergistic strengthening of nano-phase and fine-grained structure. An ultra-strong, ultra-hard, high-toughness and wear-resistant projectile surface layer is obtained through the composite gradient structure strengthening of gradient nano-phase, gradient nano-grains, gradient nano-twins and gradient dislocations. Based on the combined action of the above two, the nickel-tungsten alloy warhead projectile has excellent overall performance and breakthrough surface layer performance.

[0044] Taking the Ni-W-Co-Ta alloy as an example below, it will be described in conjunction with specific embodiments.

[0045] Example 1

[0046] (1) The nickel-tungsten alloy forging blank with a uniform fine-grained structure is solution-treated at 1040 °C for 1 h to obtain a supersaturated solid solution nickel-tungsten alloy with a uniform fine-grained structure;

[0047] (2) Ultrasonic shot peening is used to transform the micron-scale uniform fine grains on the surface layer of the supersaturated solid solution nickel-tungsten alloy with a uniform fine-grained structure into gradient nano-grains, and gradient nano-twins and gradient dislocations are formed inside the gradient grains, that is, the grains, twins and dislocations are all gradient-distributed from the surface to the interior, and the size of the nano-grains is controlled below 100 nm, obtaining a nickel-tungsten alloy with a triple composite gradient nano-structure surface layer;

[0048] (3) The nickel-tungsten alloy with a triple composite gradient nano-structure is aged at 750 °C for 5 h, and nano-phases are precipitated in a gradient from the surface to the interior, preparing a nickel-tungsten alloy with a quadruple composite gradient nano-structure;

[0049] The specific process is as follows:

[0050] The nickel-tungsten alloy forging blank with a uniform fine-grained structure is solution-treated. The solution temperature is set at 1040 °C, and the holding time is 1 h. Strictly take the sample at the arrival of temperature. After the holding is completed, immediately take out the sample and put it into an oil barrel at room temperature for oil cooling until it is completely cooled and taken out, obtaining a supersaturated solid solution nickel-tungsten alloy with a uniform fine-grained structure. The heat treatment equipment uses a silicon carbide rod box-type resistance furnace.

[0051] The surface nanocrystallization modification of the high-quality nickel-tungsten supersaturated solid solution alloy is carried out by ultrasonic shot peening. The ultrasonic shot peening process parameters are that 20 bearing steel balls with a diameter of 3 mm are accelerated in a chamber with a diameter of 50 mm by a high-frequency ultrasonic signal (20 kHz), hitting the material surface to produce severe plastic deformation. The working distance (the distance from the material to the ultrasonic vibration surface) is 10 mm, the shot peening amplitude is set at 20 μm, and the shot peening duration is 6 min. The maximum ultrasonic frequency that the ultrasonic shot peening equipment can generate is 20 kHz. The output power of the used ultrasonic shot peening equipment is 1.5 kW. The sample after ultrasonic shot peening strengthening is shown inFigure 2 , a Ni-W-Co-Ta alloy with a triple composite gradient nanostructure is obtained.

[0052] The Ni-W-Co-Ta alloy with a triple composite gradient nanostructure is subjected to aging treatment. The aging temperature is set at 750 °C, and the holding time is 5 h. Samples are strictly placed immediately upon reaching the temperature. After the holding is completed, the samples are immediately taken out and air-cooled until completely cooled to prepare a nickel-tungsten alloy with a quadruple composite gradient nanostructure. The heat treatment equipment uses a silicon carbide rod box-type resistance furnace.

[0053] Example 2

[0054] Same as Example 1, except that in (2), the shot peening duration is 2 min.

[0055] Example 3

[0056] Same as Example 1, except that in (2), the shot peening duration is 4 min.

[0057] Example 4

[0058] Same as Example 1, except that in (2), the shot peening duration is 8 min.

[0059] Example 5

[0060] Same as Example 1, except that in (2), the shot peening amplitude is 50 μm.

[0061] Example 6

[0062] Same as Example 5, except that in (2), the shot peening time is 12 min.

[0063] Example 7

[0064] Same as Example 6, except that in (3), the process parameters of the aging treatment are: holding for 4 h.

[0065] Example 8

[0066] Same as Example 6, except that in (3), the process parameters of the aging treatment are: holding for 6 h.

[0067] Example 9

[0068] Same as Example 6, except that in (3), the process parameters of the aging treatment are: holding for 7 h.

[0069] Example 10

[0070] Same as Example 1, except that it does not go through the treatment in step (1).

[0071] Example 11

[0072] Same as Example 10, except that in (2), the shot peening amplitude is 50 μm.

[0073] Example 12

[0074] Same as Example 11, except that in (2), the shot peening duration is 12 min.

[0075] Example 13

[0076] Same as Example 1, except that it does not go through the treatment in step (3).

[0077] Example 14

[0078] Same as Example 13, except that in (2), the shot peening duration is 10 min.

[0079] Comparative Example 1

[0080] Same as Example 1, except that it does not go through the treatments in steps (1), (2), and (3) (as-forged Ni-W-Co-Ta alloy).

[0081] Comparative Example 2

[0082] Same as Example 1, except that it does not go through the treatments in steps (2) and (3) (solution-treated Ni-W-Co-Ta alloy).

[0083] Comparative Example 3

[0084] Same as Example 1, except that it does not go through the treatment in step (2) (solution-aged Ni-W-Co-Ta alloy).

[0085] Comparative Example 4

[0086] Same as Example 1, except that it does not go through the treatments in steps (1) and (2) (as-forged and aged Ni-W-Co-Ta alloy).

[0087] Not going through steps (1), (2), and (3) means not going through the solution treatment in step (1), not going through the ultrasonic shot peening surface nanocrystallization treatment in step (2), and not going through the aging treatment in step (3).

[0088] Name the nickel-tungsten alloy products obtained in Examples 1 - 14 as S1 - S14, and name the nickel-tungsten alloy products obtained in Comparative Examples 1 - 4 as D1 - D4.

[0089] According to the GB / T 228.1 - 2010 standard, measure the tensile properties (tensile strength, yield strength, elongation after fracture) of the nickel-tungsten alloy on a universal material testing machine.

[0090] In the sliding friction and wear experiment, the load was 20 N, the rotating diameter was 23 mm, the relative linear velocity between the sample and the counter material was set to approximately 0.1 m / s, i.e., the rotational speed was 83 r / min, the test time was 24 min, and the total sliding distance was 140 m. Before and after the tribological test, the sample was carefully ultrasonically cleaned with ethanol and acetone. After the test, the mass loss of the sample was determined using an analytical balance with a precision of 0.01 mg.

[0091] According to the GJB 8799-2015 standard, the dynamic properties of the nickel-tungsten alloy were determined on a Hopkinson bar device. In the dynamic compression experiment, the lengths of the incident bar and the transmitted bar were both 1000 mm, the length of the impact bar was 200 mm, and the diameters were all 16 mm. The dynamic compression experiment was carried out on the specimen under a driving air pressure of 0.85 MPa.

[0092] The products obtained in Examples 1-14 and Comparative Examples 1-4 were tested, and the test results are shown in Tables 1 and 2 below.

[0093] Table 1 Product properties of Examples 1-14 and Comparative Examples 1-4

[0094]

[0095] Table 2 Product properties of Examples 1, 10 and Comparative Examples 3, 4

[0096]

[0097] From the content of Tables 1 and 2 above, it can be seen that the performance of the technical solution of the present invention is superior to that of the comparative examples.

[0098] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A nickel-tungsten alloy with a quadruple composite gradient nanostructure, characterized in that, The nickel-tungsten alloy is divided into a core part and a surface layer. The core part is composed of a nano-phase and fine-grained structure, and the surface layer is composed of a quadruple composite gradient structure of gradient nano-phase, gradient nano-grains, gradient nano-twins, and gradient dislocations.

2. The nickel-tungsten alloy with a quadruple composite gradient nanostructure according to claim 1, wherein Specifically, the nano-phase and fine-grained structure is that nano-phases are diffusely distributed inside micron-sized fine grains.

3. The nickel-tungsten alloy with a quadruple composite gradient nanostructure according to claim 1, characterized in that, The thickness of the surface layer is the depth at which gradient dislocations spread from the surface of the surface layer towards the core part; Gradient nano-phases are formed at the surface layer surface to ~A mm, gradient nano-grains are formed at the surface layer surface to ~B μm, gradient nano-twins are formed at the surface layer surface to ~C μm, and gradient dislocations are formed at the surface layer surface to ~D mm; Among them, A = D ≤ 1, B ≤ 500, C ≤ 700; The core part is the area with a depth greater than A mm from the surface of the surface layer towards the inside.

4. The preparation method of the nickel-tungsten alloy with a quadruple composite gradient nanostructure according to claim 3, characterized in that, It includes the following steps: S1. Transform the micron-sized uniform fine grains in the area of the surface layer surface to ~B μm of the nickel-tungsten alloy forging blank into gradient nano-grains, form gradient nano-twins in the area of the surface layer surface to ~C μm, and form gradient dislocations in the area of the surface layer surface to ~D mm, so that the grains, twins, and dislocations are all gradient-distributed from the surface to the inside, and a triple composite gradient nano-structure is obtained; S2. Perform aging treatment on the nickel-tungsten alloy with a triple composite gradient nano-structure obtained in step S1 at 650 - 900 °C for 1 - 7 h. Gradient nano-phases precipitate from the surface layer surface to ~A mm area from the surface to the inside, and nano-precipitation in the core part obtains a nano-phase and fine-grained structure, and a nickel-tungsten alloy with a quadruple composite gradient nano-structure is prepared.

5. The preparation method of the nickel-tungsten alloy with a quadruple composite gradient nanostructure according to claim 4, characterized in that, In step S1, the nickel-tungsten alloy forging blank is first solution-treated at 900 - 1100 °C for 0.5 - 2 h to obtain a supersaturated solid solution nickel-tungsten alloy with a uniform fine-grained structure. Then, after being treated by steps S1 and S2, the obtained nickel-tungsten alloy has higher plasticity and lower strength than the nickel-tungsten alloy without solution treatment.

6. The preparation method of the nickel-tungsten alloy with a quadruple composite gradient nanostructure according to claim 5, characterized in that, The cooling method for the solution treatment is oil cooling, and the cooling method for the aging treatment in step S2 is air cooling.

7. The preparation method of the nickel-tungsten alloy with a quadruple composite gradient nanostructure according to claim 4, characterized in that, The average grain size of the nickel-tungsten alloy forging blank in step S1 is less than 15 μm.

8. The preparation method of the nickel-tungsten alloy with a quadruple composite gradient nanostructure according to claim 4, characterized in that, In step S1, the surface nanocrystallization treatment technology is used to transform the micron-sized uniform fine grains on the surface layer into gradient nano-grains, and gradient nano-twins and gradient dislocations are formed inside the gradient nano-grains and in the direction from the surface layer to the core part; The surface nanocrystallization treatment technology is one of surface mechanical grinding treatment method, cam rolling, ultrasonic shot peening, pneumatic shot peening, laser irradiation, laser remelting, laser shot peening, and supersonic particle bombardment.

9. The preparation method of the nickel-tungsten alloy with a quadruple composite gradient nanostructure according to claim 8, characterized in that, The parameter settings for the ultrasonic shot peening process are 20 - 100 bearing steel shots or tungsten carbide shots with a diameter of 2 - 4 mm, the working distance is 8 - 15 mm, the shot peening amplitude is set to 15 - 50 μm, and the shot peening duration is 2 - 15 min.

10. The preparation method of the nickel-tungsten alloy with a quadruple composite gradient nanostructure according to claim 4, characterized in that The nickel-tungsten alloy is a Ni-W-Co-Ta alloy, and the chemical composition of the nickel-tungsten alloy by mass percentage is: Ni 47 - 64.8%, W 35 - 40%, Co 0.1 - 8%, Ta 0.1 - 5%.

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