High-strength tungsten-nickel-iron-cobalt alloy and preparation method thereof

Abstract

The invention discloses a high-strength tungsten-nickel-iron-cobalt alloy and a preparation method thereof. The preparation method of the high-strength tungsten-nickel-iron-cobalt alloy comprises the following steps that tungsten powder, nickel powder, iron powder and cobalt powder are mixed and subjected to ball milling, compression molding is conducted, and a rod-shaped tungsten-nickel-iron-cobalt alloy blank is obtained; the rod-shaped tungsten-nickel-iron-cobalt alloy blanks are sequentially sintered, and the tungsten-nickel-iron-cobalt alloy is obtained; and the tungsten-nickel-iron-cobalt alloy is sequentially subjected to dehydrogenation, hot extrusion and heat treatment, and finally the high-strength tungsten-nickel-iron-cobalt alloy is obtained. According to the preparation method, the problem that the plasticity of the hot-extrusion-state tungsten alloy is low is solved, the plasticity of the hot-extrusion-state tungsten alloy is improved under the condition that the strength is guaranteed, and the use way of the hot-extrusion-state tungsten alloy is widened.

Description

Technical Field

[0001] This invention relates to the field of tungsten alloy materials technology, specifically to a high-strength tungsten-nickel-iron-cobalt alloy and its preparation method. Background Technology

[0002] High-density tungsten alloys are alloys composed of tungsten as the matrix (tungsten content 85% to 99%) and small amounts of elements such as Ni, Fe, Co, and Mn. Due to their high density, high strength, and high elastic modulus, they are widely used in the fields of national defense, nuclear industry, and aerospace.

[0003] The properties of tungsten alloys are mainly affected by alloy composition, ball milling process, pressing process, sintering process, and post-treatment process. Common additives in tungsten alloys include refractory metals, rare earth elements and their oxides, as well as other metallic elements. Co not only improves the strength and toughness of sintered tungsten alloys but also lowers the sintering temperature and enhances the wettability between W particles and the binder phase, enabling tungsten alloys to achieve excellent comprehensive mechanical properties.

[0004] After sintering, tungsten alloys typically require deformation strengthening to improve their tensile strength. However, the grain deformation caused by deformation strengthening significantly reduces the plasticity of tungsten alloys, necessitating subsequent heat treatment to improve their performance. Therefore, finding an appropriate heat treatment process that improves plasticity while ensuring tensile strength is of great significance. Summary of the Invention

[0005] In order to overcome the shortcomings and disadvantages of the prior art, the primary objective of this invention is to provide a method for preparing a high-strength tungsten-nickel-iron-cobalt alloy. This invention prepares a high-strength tungsten-nickel-iron-cobalt alloy with a tensile strength greater than 1350 MPa and an elongation greater than 13% through a heat treatment process.

[0006] The second objective of this invention is to provide a high-strength tungsten-nickel-iron-cobalt alloy prepared by the above-described preparation method.

[0007] The primary objective of this invention can be achieved through the following technical solution:

[0008] A method for preparing a high-strength tungsten-nickel-iron-cobalt alloy includes the following steps:

[0009] (1) Mixing and ball milling: Tungsten powder, nickel powder, iron powder and cobalt powder are mixed and ball milled in a mass ratio of 93:4.4:2.1:0.5, sieved and vacuum stored to obtain mixed alloy powder;

[0010] (2) Pressing and molding: The mixed alloy powder obtained in step (1) is placed in a cold isostatic pressing furnace and pressed and molded to obtain rod-shaped tungsten-nickel-iron-cobalt alloy blanks;

[0011] (3) Sintering: The rod-shaped tungsten-nickel-iron-cobalt alloy blank obtained in step (2) is sintered in a hydrogen atmosphere;

[0012] (4) Dehydrogenation: The sintered tungsten nickel iron cobalt alloy in step (3) is subjected to dehydrogenation treatment to obtain the dehydrogenated tungsten nickel iron cobalt alloy.

[0013] (5) Hot extrusion and heat treatment: The dehydrogenated tungsten nickel iron cobalt alloy in step (5) is subjected to hot extrusion and heat treatment to prepare a high-strength tungsten nickel iron cobalt alloy.

[0014] Preferably, the tungsten powder in step (1) is spherical with a particle size of 2-5 μm and a purity ≥99.98%; the nickel powder is spherical with a particle size of 2-5 μm and a purity ≥99.99%; the iron powder is spherical with a particle size of 3-5 μm and a purity ≥99.99%; and the cobalt powder is spherical with a particle size of 2-5 μm and a purity ≥99.98%.

[0015] Preferably, the process parameters for ball milling in step (1) are as follows: ball-to-material ratio of 3 to 5:1, ball milling speed of 100 to 200 r / min, and ball milling time of 12 to 24 h. The specific speed and milling time can be determined according to actual conditions.

[0016] Preferably, the pressing molding method in step (2) is cold isostatic pressing molding, the pressing pressure is 200-250MPa, and the holding time is 120-240s.

[0017] Preferably, the specific steps of sintering in step (3) are as follows: under hydrogen conditions, first heat up to 1300°C at a heating rate of 10°C / min and hold for 30-60 minutes; then heat up to 1450-1500°C at a heating rate of 10°C / min and hold for 20-40 minutes, then cool with the furnace to complete sintering.

[0018] Preferably, the dehydrogenation treatment step in step (4) is as follows: the sintered alloy is placed in a muffle furnace and heated to 1150-1250°C in a vacuum environment at a heating rate of 10°C / min, held for 30-60 minutes, and finally cooled with water.

[0019] Preferably, in the hot extrusion process described in step (5), the deformation amount is 60%, and the hot extrusion temperature is 1200℃.

[0020] Preferably, the heat treatment temperature in step (5) is 900 to 1400°C, and the heat treatment holding time is 10 to 120 minutes.

[0021] The second objective of this invention can be achieved through the following technical solution:

[0022] A high-strength tungsten-nickel-iron-cobalt alloy is prepared by the above-described preparation method.

[0023] Preferably, the high-strength tungsten-nickel-iron-cobalt alloy has a tensile strength ≥1350MPa and an elongation ≥13%.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] While existing hot-extruded tungsten-nickel-iron-cobalt alloys exhibit high strength, they also suffer from low plasticity. The high-strength tungsten-nickel-iron-cobalt alloy preparation method described in this invention employs different heat treatment schemes to ultimately produce a tungsten-nickel-iron-cobalt alloy with a tensile strength ≥1450MPa and an elongation ≥15%, exhibiting excellent mechanical properties and facilitating widespread application. Attached Figure Description

[0026] Figure 1 These are the original morphology images of the metal powders used in Examples 1 to 7; wherein, Figure 1 a, Figure 1 b, Figure 1 c, Figure 1 d represents tungsten, cobalt, iron, and nickel powders in sequence, from... Figure 1 It can be seen from the data that all the metal powders used are spherical powders;

[0027] Figure 2 This is a microstructure of the sintered tungsten-nickel-iron-cobalt alloy from Example 3.

[0028] Figure 3 This is a microstructure diagram of the high-strength tungsten-nickel-iron-cobalt alloy grains after hot extrusion in Example 3; Figure 4 This is a comparison diagram of the grain size of the hot-extruded tungsten-nickel-iron-cobalt alloy before and after heat treatment in Example 3; Figure 4 a is a grain size diagram of the hot-extruded tungsten-nickel-iron-cobalt alloy. Figure 4 b is a grain size diagram of the tungsten-nickel-iron-cobalt alloy after heat treatment at 1100℃ for 60 min;

[0029] Figure 5 The image shows the microstructure of the tungsten-nickel-iron-cobalt alloy grains after heat treatment at 1100℃ for 60 min in Example 3.

[0030] Figure 6 The image shows the microstructure of the tungsten-nickel-iron-cobalt alloy grains after heat treatment at 1300℃ for 60 min in Example 5.

[0031] Figure 7 The tensile stress-strain curve of the tungsten-nickel-iron-cobalt alloy sample prepared in Example 3;

[0032] Figure 8 The graph shows a comparison of the mechanical properties of the high-strength tungsten-nickel-iron-cobalt alloys after heat treatment in Examples 1 to 7 and the hot-extruded control group. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. All materials used in the examples of the present invention are commercially available.

[0034] Example 1

[0035] A method for preparing a high-strength tungsten-nickel-iron-cobalt alloy, the specific preparation steps of which are as follows:

[0036] Step 1: Mixing powders

[0037] Take 465g of spherical tungsten powder with a particle size of 2.4μm and a purity of ≥99.98%, 22g of spherical nickel powder with a particle size of 2.5μm and a purity of ≥99.99%, 10.5g of spherical iron powder with a particle size of 3.0μm and a purity of ≥99.99%, and 2.5g of spherical cobalt powder with a particle size of 2μm and a purity of ≥99.98%, and pour them into a 4L stainless steel ball mill jar. Add 1500g of stainless steel balls with a diameter of 3mm. After sealing the ball mill jar, remove the air from it, introduce high-purity argon gas, and then fix it on a planetary ball mill.

[0038] Step 2: Ball milling

[0039] The ball milling parameters were set to 100 r / min and the ball milling time was 24 h. After the ball milling was completed, the stainless steel balls and alloy powder were separated by a sieve to prevent agglomeration. The sieved mixed alloy powder was placed in a vacuum bag for storage and waiting to be pressed into shape.

[0040] Step 3: Pressing and molding

[0041] After the ball-milled mixed alloy powder is loaded into a rubber sleeve and sealed with a rubber stopper, it is placed in a cold isostatic pressing furnace and held under pressure for 180 seconds. The cold isostatic pressing pressure is 225 MPa to obtain a rod-shaped tungsten-nickel-iron-cobalt alloy billet.

[0042] Step 4: Sintering

[0043] The cold isostatically pressed rod-shaped tungsten-nickel-iron-cobalt alloy billet is placed into a pusher-type sintering furnace and heated to 1300℃ at a heating rate of 10℃ / min. It is held at this temperature for 60 min, then heated to 1480℃ at a rate of 10℃ / min and held for 40 min. Finally, it is cooled with the furnace.

[0044] Step 5: Dehydrogenation

[0045] To improve the performance of tungsten-nickel-iron-cobalt alloy, the sintered alloy was placed in a muffle furnace, nitrogen was introduced as a protective gas, and then the temperature was raised to 1200℃ at a heating rate of 10℃ / min. The temperature was held at this temperature for 60 min and then water quenched.

[0046] Step 6: Hot extrusion

[0047] The dehydrogenated tungsten-nickel-iron-cobalt alloy was hot-extruded at 1200℃ with a deformation of 60%.

[0048] Step 7: Heat Treatment

[0049] The hot-extruded tungsten-nickel-iron-cobalt alloy sample was placed in a muffle furnace, held at 900℃ for 60 min, and then water-quenched to obtain a high-strength tungsten-nickel-iron-cobalt alloy sample.

[0050] The high-strength tungsten-nickel-iron-cobalt alloy sample after heat treatment in Example 1 was used as sample 1 for microstructure observation and tensile property testing for performance comparison.

[0051] like Figure 8 As shown, the average tensile strength of the tungsten-nickel-iron-cobalt alloy in Example 1 is 1387.27 MPa, and the average elongation is 13.62%.

[0052] Example 2

[0053] A method for preparing a high-strength tungsten-nickel-iron-cobalt alloy, the specific preparation steps of which are as follows:

[0054] Step 1: Mixing powders

[0055] Take 465g of spherical tungsten powder (2.4μm particle size, ≥99.98% purity), 22g of spherical nickel powder (2.5μm particle size, ≥99.99% purity), 10.5g of spherical iron powder (3.0μm particle size, ≥99.99% purity), and 2.5g of spherical cobalt powder (2μm particle size, ≥99.98% purity) and pour them into a 4L stainless steel ball mill jar; add 1500g of stainless steel balls (3mm diameter); seal the ball mill jar, remove the air, introduce high-purity argon gas, and then fix it on a planetary ball mill.

[0056] Step 2: Ball milling

[0057] The ball milling parameters were set to 100 r / min and the ball milling time was 24 h. After the ball milling was completed, the stainless steel balls and alloy powder were separated by a sieve to prevent agglomeration. The sieved mixed alloy powder was placed in a vacuum bag for storage and waiting to be pressed into shape.

[0058] Step 3: Pressing and molding

[0059] After ball milling, the mixed alloy powder is placed into a rubber sleeve and sealed with a rubber stopper. It is then placed in a cold isostatic pressing furnace and held under pressure for 180 seconds. The cold isostatic pressing pressure is 225 MPa, resulting in rod-shaped tungsten-nickel-iron-cobalt alloy billets.

[0060] Step 4: Sintering

[0061] The cold isostatically pressed rod-shaped tungsten-nickel-iron-cobalt alloy billet is placed into a pusher-type sintering furnace and heated to 1300℃ at a heating rate of 10℃ / min. It is held at this temperature for 60 min, then heated to 1480℃ at a rate of 10℃ / min and held for 40 min. Finally, it is cooled with the furnace.

[0062] Step 5: Dehydrogenation

[0063] To improve the performance of tungsten-nickel-iron-cobalt alloy, after sintering, the sintered alloy is placed in a muffle furnace, nitrogen is introduced as a protective gas, and then the temperature is raised to 1200℃ at a heating rate of 10℃ / min, held at this temperature for 60min, and then water quenched.

[0064] Step 6: Hot extrusion

[0065] The dehydrogenated tungsten-nickel-iron-cobalt alloy was hot-extruded at 1200℃ with a deformation of 60%.

[0066] Step 7: Heat Treatment

[0067] The hot-extruded tungsten-nickel-iron-cobalt alloy sample was placed in a muffle furnace, held at 1000℃ for 60 min, and then water-quenched to obtain a high-strength tungsten-nickel-iron-cobalt alloy sample.

[0068] The high-density tungsten-nickel-iron-cobalt alloy sample after heat treatment 2 was used as sample 2 for microstructure observation and tensile property testing for performance comparison.

[0069] like Figure 8 As shown, the tungsten-nickel-iron-cobalt alloy in Example 2 has an average tensile strength of 1430.13 MPa and an average elongation of 16.42%.

[0070] Example 3

[0071] A method for preparing a high-strength tungsten-nickel-iron-cobalt alloy, the specific preparation steps of which are as follows:

[0072] Step 1: Mixing powders

[0073] Take 465g of spherical tungsten powder (2.4μm particle size, ≥99.98% purity), 22g of spherical nickel powder (2.5μm particle size, ≥99.99% purity), 10.5g of spherical iron powder (3.0μm particle size, ≥99.99% purity), and 2.5g of spherical cobalt powder (2μm particle size, ≥99.98% purity) and pour them into a 4L stainless steel ball mill jar; add 1500g of stainless steel balls (3mm diameter); seal the ball mill jar, remove the air, introduce high-purity argon gas, and then fix it on a planetary ball mill.

[0074] Step 2: Ball milling

[0075] The ball milling parameters were set to 100 r / min and the ball milling time was 24 h. After the ball milling was completed, the stainless steel balls and alloy powder were separated by a sieve to prevent agglomeration. The sieved mixed alloy powder was placed in a vacuum bag for storage and waiting to be pressed into shape.

[0076] Step 3: Pressing and molding

[0077] After the ball-milled mixed alloy powder is loaded into a rubber sleeve and sealed with a rubber stopper, it is placed in a cold isostatic pressing furnace and held under pressure for 180 seconds. The cold isostatic pressing pressure is 225 MPa to obtain a rod-shaped tungsten-nickel-iron-cobalt alloy billet.

[0078] Step 4: Sintering

[0079] The cold isostatically pressed rod-shaped tungsten-nickel-iron-cobalt alloy billet is placed into a pusher-type sintering furnace and heated to 1300℃ at a heating rate of 10℃ / min. It is held at this temperature for 60 min, then heated to 1480℃ at a rate of 10℃ / min and held for 40 min. Finally, it is cooled with the furnace.

[0080] Step 5: Dehydrogenation

[0081] To improve the performance of tungsten-nickel-iron-cobalt alloy, after sintering, the sintered alloy is placed in a muffle furnace, nitrogen is introduced as a protective gas, and then the temperature is raised to 1200℃ at a heating rate of 10℃ / min, held at this temperature for 60min, and then water quenched.

[0082] Step 6: Hot extrusion

[0083] The dehydrogenated tungsten-nickel-iron-cobalt alloy was hot-extruded at 1200℃ with a deformation of 60%.

[0084] Step 7: Heat Treatment

[0085] The hot-extruded tungsten-nickel-iron-cobalt alloy sample was placed in a muffle furnace and held at 1100℃ for 60 min, followed by water quenching to obtain a high-strength tungsten-nickel-iron-cobalt alloy sample.

[0086] The high-density tungsten-nickel-iron-cobalt alloy sample after undergoing heat treatment 3 was used as sample 3 for microstructure observation and tensile property testing for performance comparison.

[0087] like Figure 2 This is a microstructure image of the sintered tungsten-nickel-iron-cobalt alloy from Example 3. Figure 3 This is a microstructure diagram of the high-strength tungsten-nickel-iron-cobalt alloy grains after hot extrusion in Example 3;

[0088] By comparison Figure 2 and Figure 3 It can be seen that the high-strength tungsten-nickel-iron-cobalt alloy grains after hot extrusion are elliptical, and this change also leads to an increase in the tensile strength of the tungsten-nickel-iron-cobalt alloy.

[0089] like Figure 4 This is a comparison diagram of the grain size of the hot-extruded tungsten-nickel-iron-cobalt alloy before and after heat treatment in Example 3; Figure 4 a is a grain size diagram of the hot-extruded tungsten-nickel-iron-cobalt alloy. Figure 4 b shows the grain size diagram of the tungsten-nickel-iron-cobalt alloy after heat treatment at 1100℃ for 60 min; through... Figure 4 It can be seen that the grain size of the tungsten-nickel-iron-cobalt alloy slightly increased after heat treatment at 100℃ for 60 min, the second phase particles were more uniform, stress concentration was avoided, and the plastic deformation capacity of the sample was improved.

[0090] like Figure 5 The image shows the microstructure of the tungsten-nickel-iron-cobalt alloy grains after heat treatment at 1100℃ for 60 min in Example 3.

[0091] like Figure 7 The tensile stress-strain curve of the tungsten-nickel-iron-cobalt alloy sample prepared in Example 3 is shown. Figure 7 It can be seen that the hot-extruded tungsten-nickel-iron-cobalt alloy products obtained after appropriate heat treatment have extremely superior tensile strength and elongation.

[0092] like Figure 8 As shown, the tungsten-nickel-iron-cobalt alloy in Example 3 has an average tensile strength of 1530.53 MPa and an average elongation of 19.11%.

[0093] Example 4

[0094] A method for preparing a high-strength tungsten-nickel-iron-cobalt alloy, the specific preparation steps of which are as follows:

[0095] Step 1: Mixing powders

[0096] Take 465g of spherical tungsten powder (2.4μm particle size, purity ≥99.98%), 22g of spherical nickel powder (2.5μm particle size, purity ≥99.99%), 10.5g of spherical iron powder (3.0μm particle size, purity ≥99.99%), and 2.5g of spherical cobalt powder (2μm particle size, purity ≥99.98%) and pour them into a 4L stainless steel ball mill jar. Add 1500g of stainless steel balls (3mm diameter); seal the ball mill jar, evacuate the air, introduce high-purity argon gas, and then fix it on a planetary ball mill.

[0097] Step 2: Ball milling

[0098] The ball milling parameters were set to 100 r / min and the ball milling time was 24 h. After the ball milling was completed, the stainless steel balls and alloy powder were separated by a sieve to prevent agglomeration. The sieved mixed alloy powder was placed in a vacuum bag for storage and waiting to be pressed into shape.

[0099] Step 3: Pressing and molding

[0100] After the ball-milled mixed alloy powder is loaded into a rubber sleeve and sealed with a rubber stopper, it is placed in a cold isostatic pressing furnace and held under pressure for 180 seconds. The cold isostatic pressing pressure is 225 MPa to obtain a rod-shaped tungsten-nickel-iron-cobalt alloy billet.

[0101] Step 4: Sintering

[0102] The cold isostatically pressed rod-shaped tungsten-nickel-iron-cobalt alloy billet is placed into a pusher-type sintering furnace and heated to 1300℃ at a heating rate of 10℃ / min. It is held at this temperature for 60 min, then heated to 1480℃ at a rate of 10℃ / min and held for 40 min. Finally, it is cooled with the furnace.

[0103] Step 5: Dehydrogenation

[0104] To improve the performance of tungsten-nickel-iron-cobalt alloy, after sintering, the sintered alloy is placed in a muffle furnace, nitrogen is introduced as a protective gas, and then the temperature is raised to 1200℃ at a heating rate of 10℃ / min. The alloy is then held at this temperature for 60 min and then water-quenched.

[0105] Step 6: Hot extrusion

[0106] The dehydrogenated tungsten-nickel-iron-cobalt alloy was hot-extruded at 1200℃ with a deformation of 60%.

[0107] Step 7: Heat Treatment

[0108] The hot-extruded tungsten-nickel-iron-cobalt alloy sample was placed in a muffle furnace and held at 1200℃ for 60 min, followed by water quenching to obtain a high-strength tungsten-nickel-iron-cobalt alloy sample.

[0109] The high-density tungsten-nickel-iron-cobalt alloy sample after undergoing heat treatment 4 was used as sample 4 for microstructure observation and tensile property testing for performance comparison.

[0110] like Figure 8 As shown, the tungsten-nickel-iron-cobalt alloy in Example 4 has an average tensile strength of 1455.20 MPa and an average elongation of 18.23%.

[0111] Example 5

[0112] A method for preparing a high-strength tungsten-nickel-iron-cobalt alloy, the specific preparation steps of which are as follows:

[0113] Step 1: Mixing powders

[0114] Take 465g of spherical tungsten powder (2.4μm particle size, ≥99.98% purity), 22g of spherical nickel powder (2.5μm particle size, ≥99.99% purity), 10.5g of spherical iron powder (3.0μm particle size, ≥99.99% purity), and 2.5g of spherical cobalt powder (2μm particle size, ≥99.98% purity) and pour them into a 4L stainless steel ball mill jar; add 1500g of stainless steel balls (3mm diameter); seal the ball mill jar, remove the air, introduce high-purity argon gas, and then fix it on a planetary ball mill.

[0115] Step 2: Ball milling

[0116] The ball milling parameters were set to 100 r / min and the ball milling time was 24 h. After the ball milling was completed, the stainless steel balls and alloy powder were separated by a sieve to prevent agglomeration. The sieved mixed alloy powder was placed in a vacuum bag for storage and waiting to be pressed into shape.

[0117] Step 3: Pressing and molding

[0118] After the ball-milled mixed alloy powder is loaded into a rubber sleeve and sealed with a rubber stopper, it is placed in a cold isostatic pressing furnace and held under pressure for 180 seconds. The cold isostatic pressing pressure is 225 MPa to obtain a rod-shaped tungsten-nickel-iron-cobalt alloy billet.

[0119] Step 4: Sintering

[0120] The cold isostatically pressed rod-shaped tungsten-nickel-iron-cobalt alloy billet is placed into a pusher-type sintering furnace and heated to 1300℃ at a heating rate of 10℃ / min. It is held at this temperature for 60 min, then heated to 1480℃ at a rate of 10℃ / min and held for 40 min. Finally, it is cooled with the furnace.

[0121] Step 5: Dehydrogenation

[0122] To improve the performance of tungsten-nickel-iron-cobalt alloy, after sintering, the sintered alloy is placed in a muffle furnace, nitrogen is introduced as a protective gas, and then the temperature is raised to 1200℃ at a heating rate of 10℃ / min. The alloy is then held at this temperature for 60 min and then water-quenched.

[0123] Step 6: Hot extrusion

[0124] The dehydrogenated tungsten-nickel-iron-cobalt alloy was hot-extruded at 1200℃ with a deformation of 60%.

[0125] Step 7: Heat Treatment

[0126] The hot-extruded tungsten-nickel-iron-cobalt alloy sample was placed in a muffle furnace and held at 1300℃ for 60 min, followed by water quenching to obtain a high-strength tungsten-nickel-iron-cobalt alloy sample.

[0127] The high-density tungsten-nickel-iron-cobalt alloy sample after heat treatment 5 was used as sample 5 for microstructure observation and tensile property testing for performance comparison.

[0128] like Figure 6 This is a microstructure image of the tungsten-nickel-iron-cobalt alloy grains after heat treatment at 1300℃ for 60 min in Example 5; (The image is composed of...) Figure 6 It can be seen that the grain growth of the tungsten-nickel-iron-cobalt alloy is more obvious when held at 1300℃ for 60 min than when held at 1100℃.

[0129] like Figure 8 As shown, the tungsten-nickel-iron-cobalt alloy in Example 5 has an average tensile strength of 1367.57 MPa and an average elongation of 23.23%.

[0130] Example 6

[0131] A method for preparing a high-strength tungsten-nickel-iron-cobalt alloy, the specific preparation steps of which are as follows:

[0132] Step 1: Mixing powders

[0133] Take 465g of spherical tungsten powder (2.4μm particle size, purity ≥99.98%), 22g of spherical nickel powder (2.5μm particle size, purity ≥99.99%), 10.5g of spherical iron powder (3.0μm particle size, purity ≥99.99%), and 2.5g of spherical cobalt powder (2μm particle size, purity ≥99.98%) and pour them into a 4L stainless steel ball mill jar. Add 1500g of stainless steel balls (3mm diameter); seal the ball mill jar, evacuate the air, introduce high-purity argon gas, and then fix it on a planetary ball mill.

[0134] Step 2: Ball milling

[0135] The ball milling parameters were set to 100 r / min and the ball milling time was 24 h. After the ball milling was completed, the stainless steel balls and alloy powder were separated by a sieve to prevent agglomeration. The sieved mixed alloy powder was placed in a vacuum bag for storage and waiting to be pressed into shape.

[0136] Step 3: Pressing and molding

[0137] After the ball-milled mixed alloy powder is loaded into a rubber sleeve and sealed with a rubber stopper, it is placed in a cold isostatic pressing furnace and held under pressure for 180 seconds. The cold isostatic pressing pressure is 225 MPa to obtain a rod-shaped tungsten-nickel-iron-cobalt alloy billet.

[0138] Step 4: Sintering

[0139] The cold isostatically pressed rod-shaped tungsten-nickel-iron-cobalt alloy billet is placed into a pusher-type sintering furnace and heated to 1300℃ at a heating rate of 10℃ / min. It is held at this temperature for 60 min, then heated to 1480℃ at a rate of 10℃ / min and held for 40 min. Finally, it is cooled with the furnace.

[0140] Step 5: Dehydrogenation

[0141] To improve the performance of tungsten-nickel-iron-cobalt alloy, after sintering, the sintered alloy is placed in a muffle furnace, nitrogen is introduced as a protective gas, and then the temperature is raised to 1200℃ at a heating rate of 10℃ / min. The alloy is then held at this temperature for 60 min and then water-quenched.

[0142] Step 6: Hot extrusion

[0143] The dehydrogenated tungsten-nickel-iron-cobalt alloy was hot-extruded at 1200℃ with a deformation of 60%.

[0144] Step 7: Heat Treatment

[0145] The hot-extruded tungsten-nickel-iron-cobalt alloy sample was placed in a muffle furnace and held at 1100℃ for 30 min, followed by water quenching. This yielded the tungsten-nickel-iron-cobalt alloy sample.

[0146] The high-density tungsten-nickel-iron-cobalt alloy sample after undergoing heat treatment 6 was used as sample 6 for microstructure observation and tensile property testing for performance comparison.

[0147] like Figure 8 As shown, the tungsten-nickel-iron-cobalt alloy in Example 6 has an average tensile strength of 1372.16 MPa and an average elongation of 14.47%.

[0148] Example 7

[0149] A method for preparing a high-strength tungsten-nickel-iron-cobalt alloy, the specific preparation steps of which are as follows:

[0150] Step 1: Mixing powders

[0151] Take 465g of spherical tungsten powder (2.4μm particle size, purity ≥99.98%), 22g of spherical nickel powder (2.5μm particle size, purity ≥99.99%), 10.5g of spherical iron powder (3.0μm particle size, purity ≥99.99%), and 2.5g of spherical cobalt powder (2μm particle size, purity ≥99.98%) and pour them into a 4L stainless steel ball mill jar. Add 1500g of stainless steel balls (3mm diameter); seal the ball mill jar, evacuate the air, introduce high-purity argon gas, and then fix it on a planetary ball mill.

[0152] Step 2: Ball milling

[0153] The ball milling parameters were set to 100 r / min and the ball milling time was 24 h. After the ball milling was completed, the stainless steel balls and alloy powder were separated by a sieve to prevent agglomeration. The sieved mixed alloy powder was placed in a vacuum bag for storage and waiting to be pressed into shape.

[0154] Step 3: Pressing and molding

[0155] After the ball-milled mixed alloy powder is loaded into a rubber sleeve and sealed with a rubber stopper, it is placed in a cold isostatic pressing furnace and held under pressure for 180 seconds. The cold isostatic pressing pressure is 225 MPa to obtain a rod-shaped tungsten-nickel-iron-cobalt alloy billet.

[0156] Step 4: Sintering

[0157] The cold isostatically pressed rod-shaped tungsten-nickel-iron-cobalt alloy billet is placed into a pusher-type sintering furnace and heated to 1300℃ at a heating rate of 10℃ / min. It is held at this temperature for 60 min, then heated to 1480℃ at a rate of 10℃ / min and held for 40 min. Finally, it is cooled with the furnace.

[0158] Step 5: Dehydrogenation

[0159] To improve the performance of tungsten-nickel-iron-cobalt alloy, after sintering, the sintered alloy is placed in a muffle furnace, nitrogen is introduced as a protective gas, and then the temperature is raised to 1200℃ at a heating rate of 10℃ / min. The alloy is then held at this temperature for 60 min and then water-quenched.

[0160] Step 6: Hot extrusion

[0161] The dehydrogenated tungsten-nickel-iron-cobalt alloy was hot-extruded at 1200℃ with a deformation of 60%.

[0162] Step 7: Heat Treatment

[0163] The hot-extruded tungsten-nickel-iron-cobalt alloy sample was placed in a muffle furnace and held at 1100℃ for 120 min, followed by water quenching to obtain a high-strength tungsten-nickel-iron-cobalt alloy sample.

[0164] The high-density tungsten-nickel-iron-cobalt alloy sample after heat treatment 7 was used as sample 7 for microstructure observation and tensile property testing for performance comparison.

[0165] like Figure 8 As shown, the tungsten-nickel-iron-cobalt alloy in Example 7 has an average tensile strength of 1370.38 MPa and an average elongation of 26.85%.

[0166] Figure 8 The graphs show a comparison of the mechanical properties of the high-strength tungsten-nickel-iron-cobalt alloys after heat treatment in Examples 1 to 7 and the hot-extruded control group; through Figure 8It can be seen that as the heat treatment temperature increases, the tensile strength of the hot-extruded tungsten-nickel-iron-cobalt alloy first increases and then decreases. This is mainly because heat treatment increases the volume fraction of the matrix phase and makes the second phase distribution more uniform. As the temperature increases, the tungsten alloy grains gradually coarsen, leading to a decrease in its tensile strength.

[0167] Based on the above experiments, the inventors concluded that the high-strength tungsten-nickel-iron-cobalt alloy sample in the hot-extruded state after heat treatment at 100℃ for 60 min exhibited the best performance, with an average tensile strength of 1530.53 MPa and an average elongation of 19.11%. Compared with the hot-extruded control group sample, which had a tensile strength of 1546.25 MPa and an elongation of 7.98%, the plasticity of the extruded tungsten-nickel-iron-cobalt alloy was significantly improved while maintaining high tensile strength.

[0168] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength tungsten-nickel-iron-cobalt alloy, characterized in that, Includes the following steps, (1) Mixing and ball milling: Tungsten powder, nickel powder, iron powder and cobalt powder are mixed and ball milled in a mass ratio of 93:4.4:2.1:0.5, sieved and vacuum stored to obtain mixed alloy powder; (2) Pressing and molding: The mixed alloy powder obtained in step (1) is placed in a cold isostatic pressing furnace and pressed and molded to obtain rod-shaped tungsten-nickel-iron-cobalt alloy blanks; (3) Sintering: The rod-shaped tungsten-nickel-iron-cobalt alloy blank obtained in step (2) is sintered in a hydrogen atmosphere; (4) Dehydrogenation: The sintered tungsten nickel iron cobalt alloy in step (3) is subjected to dehydrogenation treatment to obtain the dehydrogenated tungsten nickel iron cobalt alloy. (5) Hot extrusion and heat treatment: The dehydrogenated tungsten nickel iron cobalt alloy in step (5) is subjected to hot extrusion and heat treatment to prepare a high-strength tungsten nickel iron cobalt alloy.

2. The method for preparing the high-strength tungsten-nickel-iron-cobalt alloy according to claim 1, characterized in that, The tungsten powder mentioned in step (1) is spherical with a particle size of 2-5 μm and a purity of ≥99.98%; the nickel powder is spherical with a particle size of 2-5 μm and a purity of ≥99.99%; the iron powder is spherical with a particle size of 3-5 μm and a purity of ≥99.99%; and the cobalt powder is spherical with a particle size of 2-5 μm and a purity of ≥99.98%.

3. The method for preparing the high-strength tungsten-nickel-iron-cobalt alloy according to claim 1, characterized in that, The process parameters for ball milling in step (1) are as follows: ball-to-material ratio of 3 to 5:1, ball milling speed of 100 to 200 r / min, and ball milling time of 12 to 24 h.

4. The method for preparing the high-strength tungsten-nickel-iron-cobalt alloy according to claim 1, characterized in that, The pressing method described in step (2) is cold isostatic pressing, with a pressing pressure of 200-250 MPa and a holding time of 120-240 s.

5. The method for preparing the high-strength tungsten-nickel-iron-cobalt alloy according to claim 1, characterized in that, The specific steps of sintering described in step (3) are as follows: Under hydrogen conditions, first heat up to 1300℃ at a heating rate of 10℃ / min and hold for 30-60min; then heat up to 1450-1500℃ at a heating rate of 10℃ / min and hold for 20-40min, then cool with the furnace to complete sintering.

6. The method for preparing the high-strength tungsten-nickel-iron-cobalt alloy according to claim 1, characterized in that, The dehydrogenation process described in step (4) is as follows: the sintered alloy is placed in a muffle furnace and heated to 1150-1250°C in a vacuum environment at a heating rate of 10°C / min, held for 30-60 minutes, and finally cooled with water.

7. The method for preparing the high-strength tungsten-nickel-iron-cobalt alloy according to claim 1, characterized in that, In the hot extrusion process described in step (5), the deformation amount is 60%, and the hot extrusion temperature is 1200℃.

8. The method for preparing the high-strength tungsten-nickel-iron-cobalt alloy according to claim 1, characterized in that, The heat treatment temperature in step (5) is 900 to 1400°C, and the heat treatment holding time is 10 to 120 minutes.

9. A high-strength tungsten-nickel-iron-cobalt alloy, characterized in that, It is prepared according to any one of claims 1 to 8.

10. The high-strength tungsten-nickel-iron-cobalt alloy according to claim 9, characterized in that, The high-strength tungsten-nickel-iron-cobalt alloy has a tensile strength ≥1350MPa and an elongation ≥13%.

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