Energetic tungsten alloy and preparation method thereof

Abstract

The invention belongs to the field of tungsten alloys, and particularly relates to an energetic tungsten alloy and a preparation method thereof.The energetic tungsten alloy comprises a tungsten phase formed by tungsten and a solid solution phase formed by active metal; the mass content of the tungsten phase is not less than 75%; the active elements comprise zirconium, titanium and niobium. The tungsten content in the energetic tungsten heavy alloy manufactured in combination with laser additive manufacturing exceeds 75 wt%, on the premise that the tungsten content reaches up to 85 wt%, excellent compactness and excellent mechanical performance can still be guaranteed, the process is simple, and the production efficiency is high.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of tungsten alloy, and particularly relates to an energetic tungsten alloy and a preparation method thereof. BACKGROUND

[0002] Tungsten-zirconium alloy is a typical energetic tungsten alloy structural material, which is stable at room temperature and has high strength. Under dynamic impact load conditions, active elements such as Zr in the alloy are chemically reacted with oxygen in the environment under conditions such as high strain rate and high temperature, and a large amount of energy is released. This kind of alloy material is widely used in military warheads, which can not only penetrate the target by using its high strength, but also can damage the target in a large area by using its energy release characteristics. However, the chemical reaction between elemental W and Zr easily forms intermetallic compound W2Zr, which seriously affects the room temperature processing performance.

[0003] Currently, there are mainly two methods for preparing tungsten / zirconium alloy. 1. Powder metallurgy process: powder metallurgy can prepare alloy materials with high tungsten content. This process belongs to solid phase sintering in the sintering process, and the diffusion between elements is less, and the alloying degree is not high, so it is difficult to achieve absolute densification. 2. Vacuum melting method: vacuum melting can prepare high-density high-strength alloys, but due to the limitation of melting temperature, it is difficult to prepare high-tungsten-content alloys, and the electric arc melting time is long, which is easy to cause the phenomenon of W element settlement, and the melting of alloy elements and the organization are uneven.

[0004] Additive manufacturing can realize the rapid preparation of high-performance high-tungsten-content tungsten alloy, but existing research is limited to the additive manufacturing process research of traditional tungsten heavy alloys such as W-Ni-Fe alloy, and there is no report on the additive manufacturing of energetic tungsten heavy alloy. SUMMARY

[0005] The present application mainly provides an energetic tungsten alloy system with high tungsten content and appropriate Ti and Nb elements to inhibit brittle phase, and a laser additive manufacturing preparation method, which is simple and easy to operate, to solve the problems of low strength and poor plasticity of tungsten-zirconium energetic structural material in the prior art, and the rapid decline of alloy performance with the increase of tungsten content. The technical scheme is as follows: An energetic tungsten alloy and a preparation method thereof, comprising a tungsten phase formed by tungsten and a solid solution phase formed by active metals; the mass content of the tungsten phase is not less than 75%; the active elements include zirconium, titanium and niobium.

[0006] Further, the mass content of the zirconium is not less than 5%; the mass ratio of the titanium and the niobium is 1:0.8-1.2.

[0007] Further, the room temperature compressive strength is not less than 2200 MPa; and the compression strain rate is 25-70%.

[0008] A method for preparing the energetic tungsten alloy as described above, comprising the following steps: a. mixing tungsten powder and zirconium, titanium and niobium powder to obtain mixed powder; b. depositing the mixed powder on a clean titanium alloy plate under inert gas atmosphere.

[0009] Further, the zirconium, titanium and niobium powder is respectively zirconium powder, titanium powder and niobium powder, or ternary intermediate alloy powder, or binary intermediate alloy powder.

[0010] Further, the particle size of the mixed powder in step a is 10-450 μm; the mixed powder is spherical or non-spherical.

[0011] Further, the particle size of the tungsten powder in step a is 10-30 μm; the particle size of the zirconium, titanium and niobium powder is 50-150 μm.

[0012] Further, the laser power for deposition in step b is 3-10 kW; the spot diameter is 3-10 mm; the powder feeding rate is 20-150 g / min; the scanning speed is 300-900 mm / min; and the single-layer deposition height is 0.2-0.5 mm.

[0013] Further, the product after deposition is subjected to stress relief annealing heat treatment.

[0014] Further, the annealing temperature is 400-600 ℃, and the annealing time is 2-6 h.

[0015] By using the above scheme, the method has the following advantages: 1. The energetic high-entropy alloy with Zr and Ti as main elements is used as the matrix, and the energetic tungsten heavy alloy with W particle reinforcement is obtained, the high alloying of the matrix is used to inhibit the intermetallic compound reaction between W and Zr, and the brittle phase is avoided to obtain the energetic tungsten heavy alloy with high strength and high plasticity.

[0016] 2. The Zr-Ti-Nb alloy is used to replace elemental Zr, and the formation of intermetallic compounds is effectively inhibited by combining the small-pool super-metallurgical process characteristics of laser additive manufacturing, and the energetic tungsten heavy alloy with good compressive strength and plasticity is obtained. And the appropriate Ti and Nb elements can completely inhibit the brittle phase and promote the matrix to form a single solid solution, thereby reducing the types of matrix components and the difficulty of preparing raw material powder.

[0017] 3. The tungsten content of the energetic tungsten heavy alloy of the present application is more than 75 wt%, and under the premise of high tungsten content of up to 85 wt%, excellent density and excellent mechanical properties can be ensured.

[0018] 4、The energetic tungsten heavy alloy prepared by the method has a room temperature compressive strength of 2200-4500 MPa and a compression strain rate of 25-70%, and has the characteristics of high strength and high plasticity.

[0019] 5、The method has a low annealing heat treatment temperature, does not need a hot isostatic pressing treatment, and can be performed in an air furnace, thereby avoiding oxidation of tungsten and other elements at high temperatures.

[0020] 6、The method selects appropriate laser power, spot diameter and powder feeding rate, and can obtain high forming efficiency. The powder can be non-spherical sprayed tungsten powder, thereby expanding the raw material source and reducing the preparation difficulty. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a microstructure picture of the sample of Example 1; Figure 2 is an XRD spectrum of the sample of Example 1; Figure 3 is an interface morphology of the W phase and the matrix of the sample of Example 1, and is characterized by a TEM bright field image; Figure 4 is a quasi-static compression stress-strain curve of the sample of Example 1; Figure 5 is a microstructure picture of the sample of Example 2; Figure 6 is an interface morphology of the W phase and the matrix of the sample of Example 2, and is characterized by a TEM bright field image; Figure 7 is a quasi-static compression stress-strain curve of the sample of Example 2; Figure 8 is a quasi-static compression stress-strain curve of the sample of Example 3. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0023] Example 1: (1) The powders are weighed according to the mass ratio of W:Zr:Ti:Nb=85:5:5:5, and are mixed by a mixer for 1 h and then dried, and the mixed powders are loaded into a powder storage cylinder of a powder feeder. The particle size of the W powder is 10-30 μm, the particle size of the Zr, Ti and Nb powders is 100-250 μm, and all the powders are spherical powders.

[0024] (2) The titanium alloy plate is polished clean with a steel brush and wiped with acetone to remove surface oil stains, serving as a deposition substrate; argon gas is filled in the deposition work chamber, the oxygen content is reduced to 100 ppm, and deposition is performed according to a preset model and deposition parameters; the deposition parameters are: laser power is 3000W, scanning speed is 600mm / min, and powder feeding rate is 1.6r / min.

[0025] (3) The heat treatment temperature is set to 500℃, and the time is 2h, which removes the thermal stress generated in the deposition process and does not change the microstructure of the alloy.

[0026] The energetic tungsten heavy alloy with a tungsten content of 85% prepared by the above method has a microstructure as shown in Figure 1 , and a small amount of pores exist in the sample, but the density is still higher than 95%. Figure 1 The medium-bright phase is W, and it can be found that the melting of W is not serious, and the gray phase is the matrix phase, which is a Zr, Ti and Nb-rich matrix solid solution phase. As shown in Figure 2 , the phase composition thereof only has the matrix BCC solid solution phase and the W phase, which indicates that the chemical reaction of W and Zr at the interface between the tungsten particles and the matrix is inhibited. Further, as shown in Figure 3 , no fine intermetallic compound is generated at the interface, and the direct interface strength between the W phase and the matrix phase will not be affected by the brittle phase; as shown in Figure 4 , the tungsten content of the obtained sample reaches 85%, but the quasi-static compression strength can still reach 2320MPa, and the maximum compression strain reaches 33%, which indicates that under the premise of a high tungsten content of 85%, a small amount of Ti and Nb elements can completely inhibit the brittle phase, avoiding the problem of excessive increase of the types of matrix components in the prior art due to the additional increase of more than three elements to increase the entropy of the matrix, which causes the matrix component to have too many types, the preparation of the matrix powder is difficult, and the production efficiency is low.

[0027] Example 2: (1) Take Zr-Ti-Nb alloy, the composition of which is Zr: 36%, Ti: 32%, and Nb: 32% according to the mass fraction percentage, and prepare Zr-Ti-Nb alloy powder by a rotating electrode gas atomization method. The Zr-Ti-Nb alloy powder is spherical powder with a particle size of 100-250μm.

[0028] (2) The W powder and the Zr-Ti-Nb alloy powder are weighed and mixed according to a mass ratio of 80:20, and are fully mixed in a mixer for 1h, and are then placed in a vacuum oven for storage.

[0029] (3) The titanium alloy plate is polished clean with a steel brush and wiped with acetone to remove surface oil stains, serving as a deposition substrate. The powder is deposited according to a preset model under the protection of argon gas. The laser power is 3000W, the scanning speed is 600mm / min, and the powder feeding rate is 1.6r / min.

[0030] (4) The heat treatment temperature is set to 500℃, and the time is 2h. This process removes the thermal stress generated during the deposition process and does not change the microstructure of the alloy.

[0031] The microstructure of the energetic tungsten heavy alloy with 80% tungsten content prepared by the above method is shown in FIG. 2. It can be seen from the figure that the tungsten particles are uniformly distributed; the W-Zr intermetallic compound reaction at the interface between the tungsten particles and the matrix is inhibited. There is almost no pore formation in the sample, and a fully dense sample can be formed. In addition, it can be seen from the microscope photo of FIG. 3 that no intermetallic compound is generated at the interface. Figure 5 Figure 6 The quasi-static compression stress-strain curve of FIG. 4 shows that the quasi-static compression strength of the sample in Example 2 is 2270MPa, and the maximum compression strain is 32%. Figure 7

[0032] Example 3: The difference from Example 1 is that: The powders are weighed according to the mass ratio of W:Zr:Ti:Nb=75:9:8:8.

[0033] Figure 8 The quasi-static compression stress-strain curve of FIG. 4 shows that the quasi-static compression strength of the sample in Example 2 is 2270MPa, and the maximum compression strain is 32%.

[0034] For those skilled in the art, various corresponding changes and modifications can be made to the above-described technical solutions and concepts, and all these changes and modifications should belong to the protection scope of the claims of the present application.​​

Claims

1. An energetic tungsten alloy, characterized in that, A tungsten phase formed by tungsten and a solid solution phase formed by active metals; the mass content of the tungsten phase is not less than 75%; the active elements include zirconium, titanium and niobium.

2. The energetic tungsten alloy of claim 1, wherein, The mass content of the zirconium is not less than 5%; the mass ratio of the titanium and the niobium is 1:0.8-1.

2.

3. The energetic tungsten alloy of claim 1, wherein, The compressive strength at room temperature is not less than 2200MPa; the compressive strain rate is 25-70%.

4. A process for the production of the energetic tungsten alloy according to any one of claims 1 to 3, characterized in that The method comprises the following steps: a. mixing tungsten powder and zirconium, titanium and niobium powders to obtain mixed powders; b. depositing the mixed powders on a clean titanium alloy plate under an inert gas atmosphere.

5. The method of producing an energetic tungsten alloy according to claim 4, characterized in that, The zirconium, titanium and niobium powders are zirconium, titanium and niobium powders respectively, or ternary intermediate alloy powders, or binary intermediate alloy powders.

6. The method for preparing the energetic tungsten alloy according to claim 4, characterized in that, The particle size of the mixed powders in step a is 10-250μm; the mixed powders are spherical or non-spherical.

7. The method for preparing the energetic tungsten alloy according to claim 4, characterized in that, The particle size of the tungsten powder in step a is 10-30μm; the particle size of the zirconium, titanium and niobium powders is 100-250μm.

8. The method for preparing the energetic tungsten alloy according to claim 4, characterized in that, The laser power for deposition in step b is 3-10kW; the spot diameter is 3-10mm; the powder feeding rate is 20-150g / min; the scanning speed is 300-900mm / min; and the single-layer deposition height is 0.2-0.5mm.

9. The method for preparing the energetic tungsten alloy according to claim 4, characterized in that, The deposited product is subjected to stress relief annealing heat treatment.

10. The method for preparing the energetic tungsten alloy according to claim 9, characterized in that, The annealing temperature is 400-600℃, and the annealing time is 2-6h.

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