Tungsten alloy based on light gas gun impact strengthening and application

Abstract

The present application relates to a kind of tungsten alloy based on light gas gun impact strengthening and application.The tungsten phase of the tungsten alloy obtained by the present application has dislocation and dislocation entanglement, and grain refinement occurs in γ-(Ni, Fe) binder phase, the size of the refined grain is less than or equal to 150nm, and twin crystal is generated, and the total area of twin crystal accounts for more than 1 / 3 of the binder phase area;Wherein the dislocation density is greater than or equal to 10 8 / mm 2 , the dislocation entanglement density is greater than or equal to 10 5 / mm 2 . The tungsten alloy includes, by mass percentage: nickel 3-11%; iron 1-5%; the balance is tungsten and unavoidable impurities.The present application can control the microstructure in tungsten alloy by controlling the type of collision pair, target plate thickness, projectile diameter and impact velocity and other parameters during light gas gun loading, so that the tungsten alloy can be strengthened under a certain impact pressure without layer cracking damage.The present application has reasonable structure design, simple and controllable process, and the obtained product has wide application.

Description

Technical Field

[0001] This invention relates to the field of tungsten alloy strengthening, and specifically to a tungsten alloy based on light gas gun impact strengthening and its application. Background Technology

[0002] Tungsten alloys are a typical example of refractory metal matrix composites. They typically refer to two-phase alloys formed by sintering, with a tungsten content greater than 85%, consisting of spherical tungsten particles with a body-centered cubic (BCC) structure uniformly embedded in a face-centered cubic (FCC) γ-(Ni,Fe) binder phase. They possess advantages such as high density, high melting point, and high strength, and are often used to manufacture critical components in extreme environments such as defense, aerospace, and nuclear industries, including counterweights, vibration dampers, kinetic energy penetrators, and radiation shields. With the development of modern technology, increasingly higher requirements are being placed on the service performance of tungsten alloys in extreme environments. Currently, ultra-high strength tungsten alloys are generally obtained through deformation strengthening processes such as forging, hot extrusion, and hot rolling. However, due to the intrinsic brittleness caused by the dislocation core structure of tungsten at low strain rates at room temperature, and the difference in thermal expansion coefficients between the two phases, microscopic defects such as micropores and microcracks are easily introduced during processing, reducing the mechanical properties of tungsten alloys. Furthermore, performing the above deformation strengthening operations on difficult-to-deform high-strength tungsten alloys requires the use of specially designed molds, resulting in high costs.

[0003] Light gas cannons are simple to operate, produce reliable and highly repeatable experimental results, and exhibit good planarity and parallelism of impacts. They are mainly used in fields such as high-pressure physics and are commonly used to determine the high-pressure equation of state and dynamic tensile fracture (split fracture) strength of materials. For example, in his paper "Shock response of a heavy tungsten alloy", Dandekar used a light gas cannon to drive a flying plate to impact a 92.85W-4.9Ni-2.25Fe alloy and obtained a Hugonius elastic limit of 2.76±0.26GPa and a split fracture strength of 1.9±0.4GPa.

[0004] Light gas guns can also drive high-speed projectiles to act on the sample surface, causing high strain rate deformation. Under certain impact pressures, this can increase the dislocation and twin density in the sample, and under even higher impact pressures, phase transitions can occur. However, when a light gas gun drives a projectile to act on the sample surface, it generates a shock wave. This shock wave propagates to the free surface on the back and sides of the sample and is reflected. The interaction between the reflected wave and the incident wave causes internal lamination damage to the sample. Summary of the Invention

[0005] In response to the increasingly stringent requirements for the mechanical properties of tungsten alloys in complex service environments under the development of modern defense technology and advanced industry, the first objective of this invention is to provide a tungsten alloy based on impact strengthening by a light gas gun.

[0006] A second objective of this invention is to provide applications of the aforementioned reinforced tungsten alloy.

[0007] During the development of this invention, it was discovered that precisely controlling parameters such as the type of impact pair, target plate thickness, projectile diameter, and impact velocity during the loading process of a light gas cannon, in order to control the microstructure of the tungsten alloy, can strengthen the tungsten alloy under certain impact pressure without causing delamination damage.

[0008] This invention employs a light gas gun technique to impact and deform tungsten alloy materials, thereby altering the microstructure of the tungsten alloy through the strain rate effect, thus achieving the purpose of strengthening.

[0009] This invention discloses a tungsten alloy based on light gas gun impact strengthening. The tungsten phase of the tungsten alloy obtained by light gas gun impact strengthening contains dislocations and dislocation entanglements, and the γ-(Ni,Fe) binder phase undergoes grain refinement, with the refined grain size being less than or equal to 150 nm, and twins are generated, occupying more than 1 / 3 of the total area of ​​the binder phase region; wherein the dislocation density is greater than or equal to 10. 8 / mm 2 Dislocation entanglement density greater than or equal to 10 5 / mm 2 The tungsten alloy comprises, by weight percentage: 3-11% nickel; 1-5% iron; the balance being tungsten and unavoidable impurities.

[0010] The dislocations include nonplanar core dislocation structures and / or screw dislocations.

[0011] This invention uses a clean and dry tungsten alloy as the treatment target, employing a light gas gun to impact the tungsten alloy. During the light gas gun impact treatment, the projectile material is selected from one of 2017Al, GCr15, and WC-Co; the projectile diameter is 4.5mm to 15mm; the tungsten alloy thickness is greater than 5mm; and the projectile impact velocity on the tungsten alloy surface ranges from 430m / s to 2500m / s. The surface roughness of the clean and dry tungsten alloy is less than 50nm.

[0012] Preferably, the tungsten alloy comprises, by weight percentage: 3.5-10.5% nickel; 1.5-4.5% iron; with the balance being tungsten and unavoidable impurities.

[0013] The tungsten alloy with a clean and dry surface of the present invention is prepared by the following steps:

[0014] Before high strain rate strain strengthening by light gas gun impact, the tungsten alloy target plate needs to undergo surface treatment to make the sample surface smooth and flat, with a mirror-like finish. This facilitates the propagation and interaction of shock waves generated when the light gas gun impacts the target plate. Specifically, this includes grinding the tungsten alloy sample surface on a polishing machine using P600, P800, P1000, P1200, P1500, and P2000 diamond abrasive paper, respectively. Subsequently, the tungsten alloy surface is polished from high to low particle size using 10μm diamond polishing agent and 0.5μm alumina polishing liquid, respectively.

[0015] The inventors discovered that when using sandpaper to polish tungsten alloy samples to remove the deformed layer, the large surface area of ​​the sample makes it difficult to apply force evenly, resulting in uneven surface scratches during polishing. Furthermore, the high hardness of tungsten alloy samples makes the surface layer difficult to remove, requiring a large amount of sandpaper to remove the newly introduced deformed layer, which is inconvenient. Using a diamond grinding disc instead of sandpaper to grind high-hardness tungsten alloy samples achieves better sample surface smoothness, more uniform scratches, and easier removal. Additionally, the honeycomb structure of the diamond grinding disc reduces the contact area with the sample, requiring significantly less pressure than using a flat disc, reducing the risk of tearing and allowing for recycling, thus lowering costs. Moreover, when removing the surface deformed layer introduced by the previous cutting process, the new deformed layer is much thinner than that introduced by sandpaper, significantly improving sample preparation efficiency. The inventors also found that a large gradient in the particle size of the polishing fluid makes it difficult to eliminate fine scratches on the material surface; setting a gradient in the middle is more reasonable. Finally, they discovered that the key step in maintaining the mirror-like finish of the sample surface is the combination of polishing agents with different particle sizes and polishing cloths of different materials.

[0016] In industrial applications, to further enhance the effect, the surface of the tungsten alloy sample can be ground in sequence using diamond grinding discs numbered 0# (coarse grinding corresponding to sandpaper range P80-P120), 1# (coarse grinding corresponding to sandpaper range P120-P240), 2# (coarse grinding corresponding to sandpaper range P240-P600), 3# (medium grinding corresponding to sandpaper range P600-P800), and 4# (fine grinding corresponding to sandpaper range P1000-P1200). Subsequently, the tungsten alloy sample is finely polished in sequence using canvas with 10μm diamond polishing agent, silk cloth with 3.5μm diamond polishing agent, and short-pile cloth with 0.5μm alumina polishing liquid.

[0017] In a preferred embodiment, the tungsten alloy sample after grinding and polishing is placed in a beaker containing 2 / 3 volume of anhydrous ethanol, and then placed in an ultrasonic cleaner for ultrasonic oscillation cleaning. The ultrasonic frequency is set to 40-100 kHz, the ultrasonic temperature to 20-35°C, and the ultrasonic time to 10-30 min.

[0018] The inventors discovered that anhydrous ethanol is a hydrophilic and lipophilic organic solvent miscible with water and most organic solvents. It can effectively remove grease, organic matter, and impurities from sample surfaces. However, it readily evaporates into ethanol vapor, requiring sealing with plastic wrap. Ultrasonic cleaning machines utilize the cavitation effect of ultrasonic waves to impact and peel away contaminants from object surfaces, achieving cleaning. They are characterized by high cleaning efficiency and fast cleaning speed. However, excessively high ultrasonic frequencies and temperatures may damage the sample surface, even affecting the material's microstructure and lattice stability, while excessively low ultrasonic frequencies and temperatures will fail to clean the sample surface effectively. Furthermore, the ultrasonic time should not be too low or too high; an appropriate ultrasonic time ensures thorough cleaning without wasting costs.

[0019] Further preferably, during the anhydrous ethanol ultrasonic cleaning process, the ultrasonic frequency is set to 80 kHz, the ultrasonic temperature is set to 25 °C, and the ultrasonic time is set to 20 min.

[0020] In a preferred embodiment, the tungsten alloy sample, after being ultrasonicated with anhydrous ethanol, is removed. The sample surface is then cleaned and dried using a nitrogen gas gun at a pressure range of 0.5–1 MPa. Finally, the sample is placed in a vacuum drying oven at a temperature of 100–150°C for 10–20 minutes to ensure surface purity and dryness. After nitrogen drying, the surface roughness of the tungsten alloy can be less than 50 nm, such as 10–15 nm.

[0021] The inventors discovered that nitrogen is a dry, non-toxic, colorless, and odorless gas, commonly used in laboratories to remove impurities adhering to the surface of samples. When using a nitrogen gas gun, it is necessary to select an appropriate pressure to prevent the sample from being blown away and to dry the sample surface quickly. Similarly, when thoroughly drying the sample in a vacuum drying oven, it is also necessary to select an appropriate temperature and time to avoid damaging the sample due to excessively high temperature or prolonged high temperature.

[0022] Further preferably, the pressure of the nitrogen gas gun is set to 0.5 MPa; the temperature of the vacuum drying oven is set to 120°C, and the drying time is 15 min.

[0023] In this invention, when performing light gas cannon impact treatment on clean and dry tungsten alloy surfaces, the pre-treated tungsten alloy sample is installed in the sample chamber of a light gas cannon device. Expanded nitrogen gas drives the projectile, which accelerates within the barrel and finally impacts the tungsten alloy target plate at the muzzle after reaching the desired velocity. The light gas cannon device is a single-stage light gas cannon, capable of loading a maximum velocity of 2.5 km / s for relatively small-diameter (small-mass) projectiles, and is equipped with a soft recovery device to recover the tungsten alloy sample after the impact.

[0024] In the preferred embodiment, the projectile used during the loading process of the light gas gun is GCr15 steel, which has relatively lower strength and density compared to tungsten alloys.

[0025] The preferred design uses a projectile diameter of 5mm to 15mm, and more preferably 5mm to 10mm. The tungsten alloy sample is recovered after the impact.

[0026] The inventors discovered that when a projectile with relatively low strength and low density forms a collision pair with a target plate with higher strength and density, the crater depth increases slowly at lower impact velocities, while the crater depth increases rapidly with increasing impact velocity, resulting in greater material deformation. Furthermore, the instant the projectile collides with the target plate can be approximated as a one-dimensional planar impact. According to the Hugonius equation of state, the impact pressure P = ρ(C + SU) P )U P Where ρ (physical meaning: material density), C (physical meaning: sound velocity of the material at zero pressure), and S (physical meaning: empirical parameter) are constants that can be obtained by consulting relevant books and manuals, and U P The particle velocity in the tungsten alloy is directly proportional to the impact velocity. Therefore, a higher impact velocity results in greater projectile kinetic energy and thus higher impact pressure. This is beneficial for achieving large strain rate deformation in the tungsten alloy target plate and also promotes the formation of internal defects in the tungsten alloy, such as dislocations and twins. Therefore, it is desirable to select a small projectile diameter to obtain a large deformation and impact pressure. However, under high impact velocities, the thickness of the target plate cannot be too low. This is because during the impact of the projectile, a spherical compressive stress wave is formed at the moment of contact. The intensity of the stress wave is proportional to the impact pressure or impact velocity. When the stress wave reaches the free surface on the back of the target plate, it will be reflected, forming a tensile stress wave. During the propagation of the reflected wave, it interacts with the incident wave inside the target plate to form a combined tensile stress wave. When the intensity of the tensile stress wave reaches the critical fracture stress of the material, delamination will occur, that is, voids and cracks will form inside the target plate. Especially when the target plate is relatively thin, the path of the stress wave to the free surface is short, and the intensity of the stress wave cannot be well dissipated, resulting in a larger delamination area. However, when the thickness of the tungsten alloy target plate is increased, the propagation path of the stress wave increases, the intensity decreases, the energy is well dissipated, and the delamination phenomenon disappears.

[0027] Preferably, the velocity range of the projectile impacting the tungsten alloy surface is 1000m / s to 2500m / s.

[0028] In industrial applications, the impact velocity of the projectile on the tungsten alloy surface increases with the increase of the W content in the tungsten alloy. For example, when the W content is 85–86 wt%, a projectile impact velocity of 1000–1150 m / s can be selected. When the W content is 89–91 wt%, a projectile impact velocity of 1300–1350 m / s can be selected. When the W content is 92.5–93.5 wt%, a projectile impact velocity of 1650–1700 m / s can be selected. When the W content is 94.5–95.5 wt%, a projectile impact velocity of 2150–2250 m / s can be selected.

[0029] Following the method described above for selecting the impact velocity of the projectile on the tungsten alloy surface, to further optimize the scheme, the diameter of the projectile decreases as the W content in the tungsten alloy increases. Specifically: when the W content is 85–86 wt%, the projectile diameter is 7.8–8.2 mm; when the W content is 89–91 wt%, the projectile diameter is 6.8–7.2 mm; when the W content is 92.5–93.5 wt%, the projectile diameter is 5.8–6.2 mm; and when the W content is 94.5–95.5 wt%, the projectile diameter is 5–5.2 mm.

[0030] As a further preferred option,

[0031] When the tungsten alloy target plate material is 85W-10.5Ni-4.5Fe, the projectile diameter is 8mm, the projectile impact velocity is 1100m / s, the impact diameter of the target plate is 30mm (more than three times the projectile diameter to reduce the adverse effects of shock waves reflected from the edge of the target plate), and the thickness is greater than or equal to 6mm.

[0032] When the tungsten alloy target plate material is 90W-7Ni-3Fe, the projectile diameter is 7mm, the projectile impact velocity is 1335m / s, the impact diameter of the target plate is 30mm, and the thickness is greater than or equal to 8mm.

[0033] When the tungsten alloy target plate material is 93W-4.9Ni-2.1Fe, the projectile diameter is 6mm, the projectile impact velocity is 1680m / s, the impact diameter of the target plate is 30mm, and the thickness is greater than or equal to 10mm.

[0034] When the tungsten alloy target plate material is 95W-3.5Ni-1.5Fe, the projectile diameter is 5mm, the projectile impact velocity is 2200m / s, the impact diameter of the target plate is 30mm, and the thickness is greater than or equal to 15mm.

[0035] The inventors discovered that when the tungsten alloy target plate material is 85W-10.5Ni-4.5Fe, the projectile diameter is 6mm, the projectile impact velocity is 1679m / s, the target plate impact diameter is 30mm, and the thickness is 15mm.

[0036] When the tungsten alloy target plate material is 90W-7Ni-3Fe, the projectile diameter is 6mm, the projectile impact velocity is 1675m / s, the impact diameter of the target plate is 30mm, and the thickness is 15mm.

[0037] When the tungsten alloy target plate material is 95W-3.5Ni-1.5Fe, the projectile diameter is 6mm, the projectile impact velocity is 1685m / s, the impact diameter of the target plate is 30mm, and the thickness is 15mm.

[0038] Under the experimental conditions described above, the microstructures of 85W-10.5Ni-4.5Fe and 90W-7Ni-3Fe alloys were compressed into elongated strips under this impact velocity, losing their plastic deformation capacity, and numerous cracks initiated and propagated. The deformation of the 95W-3.5Ni-1.5Fe alloy was smaller, failing to achieve the desired effect. Therefore, a gradient design of the impact pressure or impact velocity is necessary. For tungsten alloys with relatively higher density and strength, the projectile impact velocity should be designed to be relatively higher to obtain the desired deformation, while the opposite is true for tungsten alloys with relatively lower density and strength. Furthermore, to reduce costs, the thickness of the high-performance tungsten alloy target plate can be appropriately reduced, while the thickness of other tungsten alloy target plates should be adjusted appropriately according to changes in impact velocity.

[0039] As a further preferred option,

[0040] When the tungsten alloy target plate material is 85W-10.5Ni-4.5Fe, the projectile diameter is 8mm, the projectile impact velocity is 1100m / s, the impact diameter of the target plate is 30mm, and the thickness is 6mm.

[0041] When the tungsten alloy target plate material is 90W-7Ni-3Fe, the projectile diameter is 7mm, the projectile impact velocity is 1335m / s, the target plate impact diameter is 30mm and the thickness is 8mm.

[0042] When the tungsten alloy target plate material is 93W-4.9Ni-2.1Fe, the projectile diameter is 6mm, the projectile impact velocity is 1680m / s, the impact diameter of the target plate is 30mm, and the thickness is 10mm.

[0043] When the tungsten alloy target plate material is 95W-3.5Ni-1.5Fe, the projectile diameter is 5mm, the projectile impact velocity is 2200m / s, the impact diameter of the target plate is 30mm, and the thickness is 15mm.

[0044] After completing the light gas gun impact treatment, the damaged layer on the surface of the tungsten alloy target plate needs to be removed using a wire cutting machine. Then, the sample is ground, polished, and ultrasonically cleaned in the same way as the surface pretreatment steps. Finally, a tungsten alloy material with high strength, high toughness, high hardness, and excellent fatigue performance after high strain rate strengthening by light gas gun impact is obtained.

[0045] The inventors discovered that due to severe disturbances and temperature increases in areas of large local deformation, uneven deformation occurs on the surface of tungsten alloys after impact with a light gas gun, generating adiabatic shear bands. These shear bands are often the initiation zones for voids and cracks, severely affecting the surface quality and mechanical properties of the tungsten alloy. Therefore, to restore the surface smoothness and flatness of the tungsten alloy, remove surface crack sources, release residual stress, and improve the overall mechanical properties of the tungsten alloy, it is necessary to remove the damaged layer using a wire EDM machine. Furthermore, to remove the marks left by the wire EDM machine, the surface of the tungsten alloy target plate needs to be ground, polished, and ultrasonically cleaned.

[0046] In a preferred embodiment, a wire EDM machine is used to remove the damaged layer on the surface of the tungsten alloy target plate, and then the sample is ground, polished, ultrasonically cleaned, and dried in the same manner as the surface pretreatment steps.

[0047] The present invention also provides applications of the tungsten alloy strengthened by the above-described strengthening method, wherein the tungsten alloy is applied to at least one of high-temperature structural materials, high-speed cutting tools, electrodes, filaments, electronic components and resistors, superconducting magnets and power transmission lines.

[0048] This invention is simple to operate and has significant effects.

[0049] Beneficial effects

[0050] This invention, through the design of reasonable sample surface pretreatment and posttreatment schemes, can effectively reduce costs, improve sample preparation efficiency, prevent the adverse effects of thermal shear bands on the sample surface, prevent the initiation and propagation of surface voids and cracks, and reduce damage rate.

[0051] This invention, by designing suitable lightweight gas cannon impact process parameters, including projectile size, impact velocity, and tungsten alloy target plate thickness, not only improves efficiency and reduces costs, but also effectively achieves large high strain rate deformation and impact pressure, suppressing spalling. This significantly improves the microhardness of the tungsten alloy surface material.

[0052] The light gas gun impact strengthening method designed in this invention serves as a high strain rate deformation strengthening method for tungsten alloys. During the light gas gun impact process, the high impact pressure and large strain rate deformation promote slip and strain transfer between the two phases, resulting in a large number of dislocations in the tungsten phase of the tungsten alloy, with a dislocation density greater than or equal to 10⁻⁶. 8 / mm 2 Dislocation entanglement density greater than or equal to 105 / mm 2 Due to the strain rate effect, the tungsten phase exhibits a non-planar core dislocation structure, and the activation of screw dislocations with high Peierls stress increases the slip system. Furthermore, significant grain refinement occurs in the γ-(Ni,Fe) binder phase, with grain sizes less than or equal to 150 nm, and a large number of twins are generated, occupying 1 / 3 or more of the total area of ​​the binder phase region. Due to dislocation strengthening, twin boundary strengthening, and grain boundary strengthening effects, the strength of the tungsten alloy is significantly improved. The increase in slip systems in the tungsten phase and the deformation twins in the γ-(Ni,Fe) binder phase provide a continuous source of plasticity for the tungsten alloy. All of these factors contribute to obtaining tungsten alloys with excellent mechanical properties such as strength, hardness, toughness, and fatigue resistance.

[0053] The lightweight gas gun impact high strain rate deformation strengthened tungsten alloy provided by this invention can be applied to high-temperature structural materials, high-speed cutting tools, electrodes, filaments, electronic components and resistors, superconducting magnets and power transmission lines, etc., greatly expanding the application of tungsten alloy materials. Attached Figure Description

[0054] Figure 1 The present invention provides a schematic diagram of the apparatus and a process flow diagram for the method of high strain rate deformation strengthening by impact of a light gas gun; wherein, (a) is a schematic diagram of the apparatus for the method of high strain rate deformation strengthening by impact of a light gas gun; and (b) is a process flow diagram for the method of high strain rate deformation strengthening by impact of a light gas gun.

[0055] Figure 2 The images shown are scanning electron microscope backscattered electron images of the 93W-4.9Ni-2.1Fe alloy before and after impact obtained in Example 1, where (a) is the backscattered electron image of the original 93W-4.9Ni-2.1Fe alloy sample; and (b) is the backscattered electron image of the 93W-4.9Ni-2.1Fe alloy after impact strengthening.

[0056] Figure 3 This is a comparison chart of the hardness of the original 93W-4.9Ni-2.1Fe alloy and the sample after impact strengthening with a light gas gun obtained in Example 1.

[0057] Figure 4 Transmission electron microscopy (TEM) analysis of the impact-strengthened 93W-4.9Ni-2.1Fe alloy obtained in Example 1; wherein, (a) is a bright-field TEM image of the γ-(Ni,Fe) binder phase, with the inset showing the polycrystalline diffraction rings of the γ-(Ni,Fe) binder phase; (b) is a bright-field TEM image of the tungsten phase; (c) is a selected area electron diffraction pattern of (b); (d) is a bright-field TEM image of other regions of the γ-(Ni,Fe) binder phase; (e) is a selected area electron diffraction pattern of (d); and (f) is a high-resolution TEM image of (d).

[0058] from Figure 1 It can be seen that the basic structure of the device used in this invention and the basic process flow of the technology used in this invention are as follows.

[0059] from Figure 2 It can be observed that, compared with the 93W-4.9Ni-2.1Fe alloy, the microstructure of the strengthened sample obtained in Example 1 is significantly deformed and strengthened, and the tungsten phase is elongated.

[0060] from Figure 3 It can be observed that the microhardness of the 93W-4.9Ni-2.1Fe alloy strengthened by Example 1 is significantly improved.

[0061] from Figure 4 It can be observed that in the microstructure of the impact-strengthened 93W-4.9Ni-2.1Fe alloy obtained in Example 1, the γ-(Ni,Fe) binder phase undergoes recrystallization, resulting in grain refinement and the formation of numerous nanoscale deformation twins. The tungsten phase exhibits a significant increase in dislocations, dislocation entanglement, and slip systems. These characteristics are all beneficial for obtaining tungsten alloys with excellent mechanical properties such as strength, hardness, toughness, and fatigue resistance. Detailed Implementation

[0062] Example 1

[0063] A high strain rate strain strengthening method for 93W-4.9Ni-2.1Fe alloy (i.e., the 93W-4.9Ni-2.1Fe alloy, by mass percentage, comprises: 4.9% nickel; 2.1% iron; and 93% tungsten) based on light gas gun impact, comprising the following steps:

[0064] Step 1: Surface pretreatment of tungsten alloy

[0065] A 93W-4.9Ni-2.1Fe alloy sample with a diameter of 30 mm and a thickness of 10 mm was taken and ground on an automatic grinding and polishing machine using diamond grinding discs numbered 0# (coarse grinding corresponding to sandpaper range P80-P120), 1# (coarse grinding corresponding to sandpaper range P120-P240), 2# (coarse grinding corresponding to sandpaper range P240-P600), 3# (medium grinding corresponding to sandpaper range P600-P800), and 4# (fine grinding corresponding to sandpaper range P1000-P1200). Subsequently, the sample was finely polished using canvas with 10 μm diamond polishing agent, silk cloth with 3.5 μm diamond polishing agent, and short-pile cloth with 0.5 μm alumina polishing liquid.

[0066] The ground and polished sample was placed in a beaker containing 2 / 3 volume of anhydrous ethanol, and then placed in an ultrasonic cleaner. The ultrasonic frequency was set to 80 kHz, the ultrasonic temperature to 25 ℃, and the ultrasonic time to 20 min.

[0067] After ultrasonic treatment with anhydrous ethanol, the sample surface was dried using a 0.5 MPa nitrogen gas gun. Finally, the sample was placed in a vacuum drying oven at 120°C and dried for 15 minutes to ensure the purity and dryness of the sample surface.

[0068] Step 2: Light air cannon impact treatment

[0069] The surface-pretreated sample was installed in the sample chamber of a primary light gas gun, and a 6mm diameter GCr15 steel projectile was driven to impact the sample at an impact velocity of 1680m / s. The sample was then subjected to soft recovery impact.

[0070] Step 3: Post-impact treatment of light air cannon

[0071] After the light gas gun impact treatment, the damaged layer on the sample surface is removed by wire cutting machine. The sample is then ground, polished, ultrasonically cleaned, and dried in the same manner as in step 1.

[0072] The tungsten phase of the 93W-4.9Ni-2.1Fe alloy strengthened using this invention generates a large number of dislocations (dislocation density approximately 1.1 × 10⁻⁶). 8 / mm 2 ), dislocation tangles (dislocation tangle density is approximately 1.05 × 10⁻⁶). 5 / mm 2 The slip system significantly increases, while the γ-(Ni,Fe) binder phase exhibits significant grain refinement and produces a large number of twins (grain size less than 150 nm, twins occupy 1 / 3 of the total area of ​​the binder phase region). Due to dislocation strengthening, twin boundary strengthening, and grain boundary strengthening effects, the microhardness of the 93W-4.9Ni-2.1Fe alloy is significantly improved, increasing from the initial 389 HV to 515 HV.

[0073] Example 2

[0074] A high strain rate strain strengthening method for 85W-10.5Ni-4.5Fe alloy (i.e., the 85W-10.5Ni-4.5Fe alloy, by mass percentage, comprises: 10.5% nickel; 4.5% iron; and 85% tungsten) based on light gas gun impact, comprising the following steps:

[0075] Step 1: Surface pretreatment of tungsten alloy

[0076] A 30mm diameter, 6mm thick 85W-10.5Ni-4.5Fe alloy sample was taken and ground on an automatic grinding and polishing machine using diamond grinding discs numbered 0# (coarse grinding, corresponding to sandpaper range P80-P120), 1# (coarse grinding, corresponding to sandpaper range P120-P240), 2# (coarse grinding, corresponding to sandpaper range P240-P600), 3# (medium grinding, corresponding to sandpaper range P600-P800), and 4# (fine grinding, corresponding to sandpaper range P1000-P1200). Subsequently, the sample was finely polished using canvas with 10μm diamond polishing agent, silk cloth with 3.5μm diamond polishing agent, and short-pile cloth with 0.5μm alumina polishing liquid.

[0077] The ground and polished sample was placed in a beaker containing 2 / 3 volume of anhydrous ethanol, and then placed in an ultrasonic cleaner. The ultrasonic frequency was set to 80 kHz, the ultrasonic temperature to 25 ℃, and the ultrasonic time to 20 min.

[0078] After ultrasonic treatment with anhydrous ethanol, the sample surface was dried using a 0.5 MPa nitrogen gas gun. Finally, the sample was placed in a vacuum drying oven at 120°C and dried for 15 minutes to ensure the purity and dryness of the sample surface.

[0079] Step 2: Light air cannon impact treatment

[0080] The surface-pretreated sample was installed in the sample chamber of a primary light gas gun, and an 8mm diameter GCr15 steel projectile was driven to impact the sample at an impact velocity of 1100m / s. The sample was then subjected to soft recovery impact.

[0081] Step 3: Post-impact treatment of light air cannon

[0082] After the light gas gun impact treatment, the damaged layer on the sample surface is removed by wire cutting machine. The sample is then ground, polished, ultrasonically cleaned, and dried in the same manner as in step 1.

[0083] The tungsten phase of the 85W-10.5Ni-4.5Fe alloy strengthened using this invention generates a large number of dislocations (dislocation density approximately 1.08 × 10⁻⁶). 8 / mm 2 ), dislocation entanglement (dislocation entanglement density is approximately 1×10⁻⁶) 5 / mm 2 The slip system significantly increases, while the γ-(Ni,Fe) binder phase undergoes significant grain refinement and produces a large number of twins. Due to dislocation strengthening, twin boundary strengthening, and grain boundary strengthening effects, the microhardness of the 85W-10.5Ni-4.5Fe alloy is significantly improved, from the initial 232HV to 356HV.

[0084] Example 3

[0085] A high strain rate strain strengthening method for 90W-7Ni-3Fe alloy (i.e., the 90W-7Ni-3Fe alloy comprises, by mass percentage: 7% nickel; 3% iron; 90% tungsten) based on light gas gun impact includes the following steps:

[0086] Step 1: Surface pretreatment of tungsten alloy

[0087] A 90W-7Ni-3Fe alloy sample with a diameter of 30 mm and a thickness of 8 mm was taken and ground on an automatic grinding and polishing machine using diamond grinding discs numbered 0# (coarse grinding corresponding to sandpaper range P80-P120), 1# (coarse grinding corresponding to sandpaper range P120-P240), 2# (coarse grinding corresponding to sandpaper range P240-P600), 3# (medium grinding corresponding to sandpaper range P600-P800), and 4# (fine grinding corresponding to sandpaper range P1000-P1200). Subsequently, the sample was finely polished using canvas with 10 μm diamond polishing agent, silk cloth with 3.5 μm diamond polishing agent, and short-pile cloth with 0.5 μm alumina polishing liquid.

[0088] The ground and polished sample was placed in a beaker containing 2 / 3 volume of anhydrous ethanol, and then placed in an ultrasonic cleaner. The ultrasonic frequency was set to 80 kHz, the ultrasonic temperature to 25 ℃, and the ultrasonic time to 20 min.

[0089] After ultrasonic treatment with anhydrous ethanol, the sample surface was dried using a 0.5 MPa nitrogen gas gun. Finally, the sample was placed in a vacuum drying oven at 120°C and dried for 15 minutes to ensure the purity and dryness of the sample surface.

[0090] Step 2: Light air cannon impact treatment

[0091] The surface-pretreated sample was installed in the sample chamber of a primary light gas gun, and a 7mm diameter GCr15 steel projectile was driven to impact the sample at an impact velocity of 1335m / s. The sample was then recovered by soft impact.

[0092] Step 3: Post-impact treatment of light air cannon

[0093] After the light gas gun impact treatment, the damaged layer on the sample surface is removed by wire cutting machine. The sample is then ground, polished, ultrasonically cleaned, and dried in the same manner as in step 1.

[0094] The tungsten phase of the 90W-7Ni-3Fe alloy strengthened by this invention generates a large number of dislocations (dislocation density approximately 1.09 × 10⁻⁶). 8 / mm 2 ), dislocation tangles (dislocation tangle density is approximately 1.02 × 10⁻⁶). 5 / mm 2The slip system significantly increases, while the γ-(Ni,Fe) binder phase undergoes significant grain refinement and produces a large number of twins. Due to dislocation strengthening, twin boundary strengthening, and grain boundary strengthening effects, the microhardness of the 90W-7Ni-3Fe alloy is significantly improved, from the initial 290HV to 423HV.

[0095] Example 4

[0096] A high strain rate strain strengthening method for 95W-3.5Ni-1.5Fe alloy (i.e., the 95W-3.5Ni-1.5Fe alloy comprises, by mass percentage: 3.5% nickel; 1.5% iron; 95% tungsten) based on light gas gun impact, comprising the following steps:

[0097] Step 1: Surface pretreatment of tungsten alloy

[0098] A 95W-3.5Ni-1.5Fe alloy sample with a diameter of 30mm and a thickness of 15mm was taken and ground on an automatic grinding and polishing machine using diamond grinding discs numbered 0# (coarse grinding corresponding to sandpaper range P80-P120), 1# (coarse grinding corresponding to sandpaper range P120-P240), 2# (coarse grinding corresponding to sandpaper range P240-P600), 3# (medium grinding corresponding to sandpaper range P600-P800), and 4# (fine grinding corresponding to sandpaper range P1000-P1200). Subsequently, the sample was finely polished using canvas with 10μm diamond polishing agent, silk cloth with 3.5μm diamond polishing agent, and short-pile cloth with 0.5μm alumina polishing liquid.

[0099] The ground and polished sample was placed in a beaker containing 2 / 3 volume of anhydrous ethanol, and then placed in an ultrasonic cleaner. The ultrasonic frequency was set to 80 kHz, the ultrasonic temperature to 25 ℃, and the ultrasonic time to 20 min.

[0100] After ultrasonic treatment with anhydrous ethanol, the sample surface was dried using a 0.5 MPa nitrogen gas gun. Finally, the sample was placed in a vacuum drying oven at 120°C and dried for 15 minutes to ensure the purity and dryness of the sample surface.

[0101] Step 2: Light air cannon impact treatment

[0102] The surface-pretreated sample was installed in the sample chamber of a primary light gas gun, and a 5mm diameter GCr15 steel projectile was driven to impact the sample at an impact velocity of 2200m / s. The sample was then recovered by soft impact.

[0103] Step 3: Post-impact treatment of light air cannon

[0104] After the light gas gun impact treatment, the damaged layer on the sample surface is removed by wire cutting machine. The sample is then ground, polished, ultrasonically cleaned, and dried in the same manner as in step 1.

[0105] The tungsten phase of the 95W-3.5Ni-1.5Fe alloy strengthened using this invention generates a large number of dislocations (dislocation density approximately 1.15 × 10⁻⁶). 8 / mm 2 ), dislocation tangles (dislocation tangle density is approximately 1.08 × 10⁻⁶). 5 / mm 2 The slip system significantly increases, while the γ-(Ni,Fe) binder phase undergoes significant grain refinement and produces a large number of twins. Due to dislocation strengthening, twin boundary strengthening, and grain boundary strengthening effects, the microhardness of the 95W-3.5Ni-1.5Fe alloy is significantly improved, from the initial 400HV to 597HV.

[0106] Example 5

[0107] All other conditions were the same as in Example 1, except that the sample thickness used was different when the 93W-4.9Ni-2.1Fe alloy was strengthened by light air gun impact: the sample thickness was 12 mm.

[0108] The 93W-4.9Ni-2.1Fe alloy obtained by Comparative Example 2 is similar to that of Example 1. After removing the surface damage layer, the deformation amount and microhardness of the sample are basically the same as those of Example 1. The microhardness increased from the original 389HV to 517HV. Therefore, increasing the sample thickness will not affect the deformation area.

[0109] Comparative Example 1

[0110] All other conditions were the same as in Example 1, except that the sample thickness used was different when the 93W-4.9Ni-2.1Fe alloy was strengthened by light air gun impact: the sample thickness was 5 mm.

[0111] The 93W-4.9Ni-2.1Fe alloy obtained by Comparative Example 1 had too small a thickness, so the stress wave intensity could not be dissipated and interacted with each other inside the sample to generate a large number of lamination regions. A large number of cracks were initiated and propagated. The microhardness of the 93W-4.9Ni-2.1Fe alloy increased from the original 389HV to 395HV, and the strengthening effect was not good.

[0112] Comparative Example 2

[0113] All other conditions are the same as in Example 1, except that the diameter of the projectile used is different when the 93W-4.9Ni-2.1Fe alloy is strengthened by light air gun impact: the diameter of the projectile is 15mm, and the impact velocity is 425m / s.

[0114] Using the 93W-4.9Ni-2.1Fe alloy obtained in Comparative Example 2, the impact-affected area on the sample surface increased due to the larger projectile diameter. However, due to the low impact velocity, only an insignificant adiabatic shear phenomenon occurred on the sample surface. After removing the surface damage layer, the tungsten alloy deformation was not obvious, and the microhardness changed from the original 389HV to 390HV, indicating a poor strengthening effect.

[0115] Comparative Example 3

[0116] All other conditions were the same as in Example 1, except that the nitrogen pressure was reduced to make the projectile velocity 948 m / s when the 93W-4.9Ni-2.1Fe alloy was strengthened by light gas gun impact.

[0117] Using the 93W-4.9Ni-2.1Fe alloy obtained in Comparative Example 3, due to the lower impact velocity, the sample deformation was small, and the microhardness increased from the original 389HV to 410HV, which did not achieve the required strengthening effect.

[0118] Comparative Example 4

[0119] All other conditions were the same as in Example 1, except that the tungsten alloy material was replaced with 95W-3.5Ni-1.5Fe alloy.

[0120] The 95W-3.5Ni-1.5Fe alloy obtained in Comparative Example 4 has higher density and strength than the 93W-4.9Ni-2.1Fe alloy. Under a certain impact pressure, its deformation is smaller. The microhardness of the 95W-3.5Ni-1.5Fe alloy increased from the original 400HV to 419HV, which did not achieve the required strengthening effect.

Claims

1. A tungsten alloy based on light gas gun impact strengthening, characterized in that: The tungsten alloy obtained by light gas gun impact strengthening exhibits dislocations and dislocation entanglements in its tungsten phase, and grain refinement occurs in the γ-(Ni, Fe) binder phase. The refined grain size is less than or equal to 150 nm, and twins are generated, occupying more than 1 / 3 of the total area of ​​the binder phase region; the dislocation density is greater than or equal to 10. 8 / mm 2 Dislocation entanglement density greater than or equal to 10 5 / mm 2 The tungsten alloy comprises, by weight percentage: 3-11% nickel; 1-5% iron; the balance being tungsten and unavoidable impurities. Using a clean and dry tungsten alloy as the treatment object, a light gas gun is used to impact the tungsten alloy; during the light gas gun impact treatment, the material of the projectile is selected from one of 2017Al, GCr15, and WC-Co; the diameter of the projectile is 4.5 mm to 15 mm; the thickness of the tungsten alloy is greater than 5 mm, and the surface roughness of the clean and dry tungsten alloy is less than 50 nm. The velocity of the projectile impacting the tungsten alloy surface increases with the increase of W content in the tungsten alloy; When the W content is 85~86wt%, the velocity of the projectile impacting the tungsten alloy surface is selected to be 1000~1150m / s; the diameter of the projectile is 7.8-8.2mm. When the W content is 89~91wt%, the velocity of the projectile impacting the tungsten alloy surface is selected to be 1300~1350m / s; the diameter of the projectile is 6.8-7.2mm. When the W content is 92.5~93.5wt%, the velocity of the projectile impacting the tungsten alloy surface is selected to be 1650~1700m / s; the diameter of the projectile is 5.8-6.2mm. When the W content is 94.5~95.5wt%, the velocity of the projectile impacting the tungsten alloy surface is selected to be 2150~2250m / s; the diameter of the projectile is 5-5.2mm.

2. The tungsten alloy based on light gas gun impact strengthening according to claim 1, characterized in that: A clean and dry tungsten alloy is prepared by the following steps; Before the light gas gun impact high strain rate strain strengthening, the tungsten alloy target plate is surface treated to make the sample surface smooth and flat with a mirror finish. Specifically, the surface of the tungsten alloy sample is ground on a polishing machine with P600, P800, P1000, P1200, P1500 and P2000 diamond sandpaper respectively. Then, the tungsten alloy surface is polished from high to low with diamond polishing agent with a particle size of 10 µm and alumina polishing liquid with a particle size of 0.5 µm respectively.

3. The tungsten alloy based on light gas gun impact strengthening according to claim 1, characterized in that: The polished tungsten alloy sample was placed in a beaker containing 2 / 3 volume of anhydrous ethanol, and then placed in an ultrasonic cleaner for ultrasonic oscillation cleaning. The ultrasonic frequency was set to 40~100 kHz, the ultrasonic temperature to 20~35 ℃, and the ultrasonic time to 10~30 min.

4. A tungsten alloy based on light gas gun impact strengthening according to claim 3, characterized in that: After ultrasonication with anhydrous ethanol, the tungsten alloy sample was removed, and then the sample surface was cleaned and dried with a nitrogen gas gun with a pressure range of 0.5~1 MPa. Finally, the sample was placed in a vacuum drying oven with a temperature of 100~150 ℃ and a drying time of 10~20 min.

5. A tungsten alloy based on light gas gun impact strengthening according to claim 1, characterized in that: The light gas cannon uses GCr15 steel projectiles as projectiles during loading.

6. A tungsten alloy based on light gas gun impact strengthening according to claim 5, characterized in that: When the tungsten alloy target plate material is 85W-10.5Ni-4.5Fe, the projectile diameter is 8 mm, the projectile impact velocity is 1100 m / s, the impact diameter of the target plate is 30 mm, and the thickness is greater than or equal to 6 mm. When the tungsten alloy target plate material is 90W-7Ni-3Fe, the projectile diameter is 7 mm, the projectile impact velocity is 1335 m / s, the impact diameter of the target plate is 30 mm, and the thickness is greater than or equal to 8 mm. When the tungsten alloy target plate material is 93W-4.9Ni-2.1Fe, the projectile diameter is 6 mm, the projectile impact velocity is 1680 m / s, the impact diameter of the target plate is 30 mm, and the thickness is greater than or equal to 10 mm. When the tungsten alloy target plate material is 95W-3.5Ni-1.5Fe, the projectile diameter is 5 mm, the projectile impact velocity is 2200 m / s, the impact diameter of the target plate is 30 mm, and the thickness is greater than or equal to 15 mm.

7. An application of the tungsten alloy based on light gas gun impact strengthening as described in any one of claims 1-6, characterized in that: The tungsten alloy is used in at least one of the following: high-temperature structural materials, high-speed cutting tools, electrodes, filaments, electronic components and resistors, superconducting magnets, and power transmission lines.

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