Double-structure high-entropy-tungsten heavy alloy and preparation method thereof

Abstract

The invention relates to the technical field of high-entropy-tungsten heavy alloy microstructure design and construction, in particular to a double-structure high-entropy-tungsten heavy alloy with excellent comprehensive performance and a preparation method of the double-structure high-entropy-tungsten heavy alloy. According to the double-structure high-entropy-tungsten heavy alloy designed by the invention, a bottom layer W is composed of dendritic crystals, and the dendritic crystals are a BCC phase and a mu phase which are uniformly distributed in an FCC phase matrix; the top layer W is embedded in the FCC matrix in the form of a core-shell structure; in the double-structure high-entropy-tungsten heavy alloy, the mass percentage of the high-entropy alloy is 10-20%, and the balance is W; the high-entropy alloy comprises Co, Cr, Fe, Ni and Mn. The product is prepared by adopting a laser printing (laser directional energy deposition) process. Under the synergistic effect of the components and the process, the product with extremely excellent overall wear resistance is obtained. The composition and the structure are reasonable in design, the preparation process is simple and controllable, and the obtained product is excellent in performance and convenient for industrial application.

Description

Technical Field

[0001] The invention relates to the technical field of high entropy-tungsten heavy alloy microstructure design and construction, and more specifically to a high entropy-tungsten heavy alloy with a dual structure and excellent mechanical properties and a preparation method thereof. Background Art

[0002] By doping various high entropy system alloys, high entropy-tungsten heavy alloys have their strength and plasticity further enhanced by their unique cocktail effect. At the same time, they show good fatigue resistance, high temperature stability, low temperature toughness and high wear resistance, making high entropy-tungsten heavy alloys more excellent than traditional tungsten alloys. Therefore, high entropy-tungsten heavy alloys have become ideal materials for use in the fields of machinery and mold preparation.

[0003] Bearings and tools are the most widely used components in the field of machinery and mold preparation, and their performance is directly related to the service life of the entire equipment. Therefore, high entropy-tungsten heavy alloys used in the field of machinery and mold preparation should pay more attention to properties such as hardness, high wear resistance and high temperature hardness. In the prior art, such as patent CN116103527A, a method for preparing a high entropy tungsten heavy alloy with excellent mechanical properties is involved, which uses ball milling, hot pressing, rolling, and recrystallization annealing to obtain a heterogeneous structure tungsten heavy alloy product. However, the brittleness of tungsten at room temperature increases its difficulty in making complex molds. Although people have tried to use additive manufacturing to prepare high-density tungsten alloys, such as patent CN109182871A, which involves the relevant technology of preparing fine-grained high-density tungsten alloys using laser rapid prototyping technology, as a bearing material, it will be in dry friction for a long time, which will have a great impact on the life of the parts.

[0004] Therefore, the present invention designs a high-entropy-tungsten heavy alloy material with dual-structure characteristics, which can be customized according to different performance requirements by adjusting process control parameters. The preparation of the dual-phase high-entropy-tungsten heavy alloy can reduce production costs and resource waste to a certain extent. Summary of the invention

[0005] The purpose of the present invention is to provide a dual-structure high-entropy-tungsten heavy alloy and a preparation method thereof, and to apply the dual-structure high-entropy-tungsten heavy alloy to enhance the mechanical properties of the high-entropy-tungsten heavy alloy so as to solve the problems raised in the above-mentioned background technology.

[0006] The present invention discloses a dual-structure high-entropy-tungsten heavy alloy, wherein the bottom tungsten dendrite region is organized into a BCC phase and a μ phase and is uniformly dispersed in an FCC phase matrix; the top tungsten is embedded in the FCC matrix in the form of a core-shell structure; in the dual-structure high-entropy-tungsten heavy alloy, the mass percentage of W is 80-90%; and the high-entropy alloy contains Co, Cr, Fe, Ni and Mn.

[0007] Preferably, for the dual - structure high - entropy tungsten heavy alloy of the present invention, the atomic ratio of Co, Cr, Fe, Ni, and Mn is (0.5~1.5):(0.5~1.5):(0.5~2.0):(0.5~1.5):(0.5~1.2).

[0008] A preparation method of a dual - structure high - entropy tungsten heavy alloy of the present invention; the method comprises the following steps:

[0009] (1) Uniformly mix the elemental raw material powders to obtain a pre - mixed powder of CoCrFeNiMn high - entropy alloy; uniformly mix the W powder and the pre - mixed powder of CoCrFeNiMn high - entropy alloy to obtain the standby printing raw material, and vacuum - dry the printing raw material;

[0010] The pre - mixed powder of CoCrFeNiMn high - entropy alloy contains Co, Cr, Fe, Ni, and Mn;

[0011] (2) Using the dried printing raw material as the object, perform laser printing to obtain a high - entropy tungsten heavy alloy; during laser printing, control: the laser power is 800~1200W, the scanning speed is 3~4mm / s, the single - layer thickness is 0.4~0.6mm, the scanning spacing is 0.8~1.2mm, the inter - layer cooling time is 20~40s, and the inter - layer angle is 45~90°.

[0012] Preferably, in step (1), the atomic ratio of Co, Cr, Fe, Ni, and Mn is (0.5~1.5):(0.5~1.5):(1.0~2.0):(0.5~1.5):(0.5~1.2); the particle size of the W powder and each elemental raw material powder is ≤150μm; based on the dry material, the mass percentage content of the W powder in the standby printing raw material is 80~90%;

[0013] As a further preference, in step (1), the atomic ratio of Co, Cr, Fe, Ni, and Mn is (0.9~1.1):(0.9~1.1):(0.9~1.1):(0.9~1.1):(0.9~1.1). This of course includes the case where the atomic ratio of Co, Cr, Fe, Ni, and Mn is 1:1:1:1:1.

[0014] Preferably, in step (1), the particle size of the spherical powders of Co, Cr, Fe, Ni, and Mn is 53~150μm.

[0015] Preferably, in step (1), Co powder, Cr powder, Fe powder, Ni powder and Mn powder are weighed according to the designed ratio; then ball milling and mixing are carried out to obtain the pre-mixed CoCrFeNiMn high-entropy alloy powder after ball milling. During ball milling, the mass ratio of balls to materials is controlled to be 1-5:1, the rotation speed of ball milling and mixing is 100-300 rpm, and the time of ball milling and mixing is 20-60 min.

[0016] Preferably, in step (1), the mass ratio of W powder to the pre-mixed CoCrFeNiMn high-entropy alloy powder is (80-90):(10-20).

[0017] As a further preference, in step (1), the mass ratio of W powder to the pre-mixed CoCrFeNiMn high-entropy alloy powder is 80-81:19-20 or 90-91:9-10. This of course includes 80:20 and 90:10.

[0018] Preferably, in step (1), the rotation speed of uniform mixing is 120-180 rpm, and the mixing time is 2-6 h.

[0019] Preferably, the temperature for drying the standby powder is 60-100 °C, and the heat preservation time is 250-350 min.

[0020] Preferably, in step (2), during laser printing, the power is 800-1200 W, the scanning speed is 3-4 mm / s, the single-layer thickness is 0.4-0.6 mm, the scanning spacing is 0.8-1.2 mm, the interlayer cooling is 20-40 s, the interlayer angle is 90°; the laser spot is 1 mm.

[0021] When the CoCrFeNiMn high-entropy alloy prefabricated mixed powder is composed of Co powder, Cr powder, Fe powder, Ni powder, and Mn powder in a molar ratio of 1:1:1:1:1, and the mass ratio of tungsten powder to the CoCrFeNiMn high-entropy alloy prefabricated mixed powder is 90:10, the process parameters are controlled during laser printing: the laser power of the bottom layer is 1000 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; when printing the top layer, the laser power is 900 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; at this time, the wear resistance of the bottom of the product is better. When the process parameters are controlled during laser printing: the laser power of the bottom layer is 900 W, the scanning speed is 3 mm / s, the powder feeding speed is 6.5 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; when printing the top layer, the laser power is 800 W, the scanning speed is 3 mm / s, the powder feeding speed is 6.5 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; at this time, the wear resistance of the top of the product is improved.

[0022] When the CoCrFeNiMn high-entropy alloy prefabricated mixed powder is composed of Co powder, Cr powder, Fe powder, Ni powder, and Mn powder in a molar ratio of 1:1:1:1:1, and the mass ratio of tungsten powder to the CoCrFeNiMn high-entropy alloy prefabricated mixed powder is 80:20, the process parameters are controlled during laser printing: the laser power of the bottom layer is 900 W, the scanning speed is 3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; when printing the top layer, the laser power is 800 W, the scanning speed is 3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s. At this time, the wear resistance of the top and bottom of the product can reach extremely excellent effects.

[0023] The beneficial effects of the present invention:

[0024] (1) The high-entropy tungsten heavy alloy prepared by the present invention has a uniform tissue distribution, showing a typical dual-structure distribution. The tissue in the bottom dendritic region is composed of BCC phase and μ phase evenly dispersed in the FCC phase matrix, and the phases are closely connected; the top layer of tungsten is embedded in the FCC matrix in the form of a core-shell structure. Through the coupling effect between different structures, the plasticity is improved while ensuring the hardness;

[0025] (2) The high-entropy tungsten heavy alloy is prepared by the method of laser printing (laser directed energy deposition). During the forming process of the bottom layer, benefiting from the regulation of different process parameters (laser power, scanning speed, powder feeding amount, interlayer cooling time), the effect of element rearrangement is promoted, and the uniform distribution of W and each high-entropy element in the bottom layer is realized, thereby further improving the strength-plasticity matching degree; the top layer realizes the tight coating of W particles and the high-entropy phase through the non-equilibrium solidification effect, forming a core-shell structure tissue, so that the surface layer has good strength and wear resistance;

[0026] (3) The high-entropy tungsten heavy alloys prepared by the present invention with different powder ratios show different performance characteristics. Among them, the top layer of the sample prepared with 90wt.% tungsten shows high hardness and a relatively high wear rate, which can provide a wet lubricating friction medium for bearings and reduce friction damage; while the sample prepared with 80wt.% tungsten shows consistent strength-plasticity matching up and down, and has good development prospects in fields such as cutting tools. Description of the Drawings

[0027] Figure 1 is the metallographic diagram of the 10wt.% high-entropy - 90wt.% tungsten heavy alloy material in Example 1 of the present invention;

[0028] Figure 2 is the SEM diagram of the top layer core-shell structure of the 10wt.% high-entropy - 90wt.% tungsten heavy alloy material in Example 1 of the present invention;

[0029] Figure 3 is the SEM diagram of the bottom layer dendrite of the 10wt.% high-entropy - 90wt.% tungsten heavy alloy material in Example 1 of the present invention;

[0030] Figure 4 is the metallographic diagram of the 20wt.% high-entropy - 80wt.% tungsten heavy alloy material in Example 2 of the present invention;

[0031] Figure 5 is the SEM diagram of the top layer core-shell structure of the 20wt.% high-entropy - 80wt.% tungsten heavy alloy material in Example 2 of the present invention;

[0032] Figure 6 is the SEM diagram of the bottom layer dendritic structure of the 20wt.% high-entropy - 80wt.% tungsten heavy alloy material in Example 2 of the present invention;

[0033] Figure 7 For Example 1 and 2 of the present invention and the microhardness and elastic modulus of pure tungsten;

[0034] Figure 8 For Example 1 and 2 of the present invention and the wear rate of pure tungsten at room temperature;

[0035] Combined with Figure 1 、 2 、3, 4, 5, 6, it can be seen that the parameters in the present invention can stably form a dual - structure feature with a core - shell structure mainly in the upper layer and a dendritic structure mainly in the lower layer. By adjusting the ratio of tungsten to the high - entropy alloy, the proportion of the two structures can be controlled;

[0036] From Figure 7 it can be seen that the present invention can improve the elastic modulus while maintaining the high hardness of tungsten itself, and its ability to resist elastic deformation is further enhanced;

[0037] From Figure 8 it can be seen that the present invention further enhances the interfacial bonding force of the two - phase by forming a dual - structure, resulting in a reduced wear rate and improved friction performance. Specific Embodiments

[0038] The following further describes the present invention in detail with specific embodiments.

[0039] The present invention provides a preparation method of a laser - printed (laser - directed energy deposition) high - entropy - tungsten heavy alloy, comprising the following steps:

[0040] (1) Uniformly mix the raw powder of each elemental element to obtain a pre - mixed powder of CoCrFeNiMn high - entropy alloy; uniformly mix the W powder and the pre - mixed powder of CoCrFeNiMn high - entropy alloy to obtain the raw material for printing, and vacuum - dry the raw material for printing;

[0041] (2) Laser - print the dried raw material for printing to obtain a high - entropy - tungsten heavy alloy.

[0042] In the present invention, in the pre - mixed powder of CoCrFeNiMn high - entropy alloy, the preferred atomic ratio of Co, Cr, Fe, Ni, and Mn is (0.5~1.5):(0.5~1.5):(0.5~2.0):(0.5~1.5):(0.5~1.2); more preferably (0.8~1.2):(0.8~1.2):(1.0~1.5):(1.0~1.5):(0.8~1.2).

[0043] In the present invention, the elemental powder of Co, Cr, Fe, Ni, and Mn is preferably spherical powder, and the preferred particle size of the spherical powder is 53~150μm.

[0044] In the present invention, the CoCrFeNiMn high-entropy alloy prefabricated mixed powder is obtained by ball-milling and mixing elemental powder, and the mass ratio of the ball to the material is 1 to 5:1, preferably 1 to 3:1; more preferably 2:1; the rotation speed of the ball-milling and mixing treatment is 100 to 300 rpm, preferably 120 to 200 rpm; more preferably 150 to 200 rpm; the time of the ball-milling and mixing treatment is 20 to 60 min, preferably 30 to 50 min, more preferably 30 to 40 min.

[0045] In the present invention, the mass ratio of the W powder to the CoCrFeNiMn high-entropy alloy prefabricated mixed powder is (80 to 90):(10 to 20), preferably 80:20 or 90:10.

[0046] In the present invention, the tungsten powder is preferably spherical tungsten powder with a particle size of 53 to 150 μm.

[0047] In the present invention, the uniform mixing is carried out in a drum-type mixing device, the rotation speed is 120 to 180 rpm, preferably 140 to 160 rpm; more preferably 150 rpm; the mixing time is 2 to 6 h, preferably 3 to 5 h; more preferably 4 h.

[0048] In the present invention, the drying treatment is carried out in a vacuum drying oven, the temperature is 60 to 100 °C, preferably 70 to 90 °C; more preferably 80 °C; the heat preservation time is 250 to 350 min, preferably 280 to 320 min; more preferably 300 min.

[0049] In the present invention, the model of the laser printing device is a printing device of BLT-C400, the printing method is laser printing (laser direct energy deposition), and the energy density formula is:

[0050]

[0051] In the formula: P is the laser power (W), v is the scanning rate (mm / s), h is the scanning spacing (mm), and t is the single-layer thickness (mm).

[0052] In the present invention, the energy density of the bottom dendritic structure is preferably 400 to 450 J / mm 3 when it is the best; the energy density of the top core-shell structure is preferably 360 to 380 J / mm 3 when it is the best.

[0053] In the present invention, during laser printing, the bottom layer power is 800 - 1200 W, preferably 850 - 1100 W, and more preferably 900 - 1000 W; the scanning speed is 3 - 4 mm / s, preferably 3.2 - 3.4 mm / s, and more preferably 3.3 mm / s; the single layer thickness is 0.4 - 0.6 mm, preferably 0.5 mm; the scanning pitch is 0.8 - 1.6 mm, preferably 0.9 - 1.5 mm, and more preferably 1.4 - 1.6 mm; the interlayer cooling is 20 - 40 s, preferably 30 s; the interlayer angle is 90°; the top layer power is 700 - 1000 W, preferably 750 - 950 W, and more preferably 800 - 900 W; the scanning speed is 3 - 4 mm / s, preferably 3.2 - 3.4 mm / s, and more preferably 3.3 mm / s; the single layer thickness is 0.4 - 0.6 mm, preferably 0.5 mm; the scanning pitch is 0.8 - 1.6 mm, preferably 0.9 - 1.5 mm, and more preferably 1.4 - 1.6 mm; the interlayer cooling is 20 - 40 s, preferably 30 s; the interlayer angle is 90°.

[0054] The present invention will be further described in detail with specific embodiments below.

[0055] Table 1 shows the data and application scenarios of Example 1, Example 2 and the comparative example of the present invention.

[0056] Example 1

[0057] Step 1: The elemental powders Co powder, Cr powder, Fe powder, Ni powder, Mn powder (the particle size of each powder is 53 - 150 μm) are ball - milled and mixed to obtain a CoCrFeNiMn high - entropy alloy pre - mixed powder;

[0058] Among them, the molar ratio of the elemental powders Co powder, Cr powder, Fe powder, Ni powder, Mn powder is 1:1:1:1:1; during ball - milling and mixing, the ball - to - material mass ratio is 2:1; the rotation speed of the ball - milling and mixing treatment is 200 rpm; the time of the ball - milling and mixing treatment is 30 min.

[0059] Step 2: Using tungsten powder as raw material A (particle size is 53 - 150 μm) and the CoCrFeNiMn high - entropy alloy pre - mixed powder as raw material B; by mass ratio, raw material A: raw material B=(90:10); the raw materials are prepared; then raw material A and raw material B are mixed evenly (the even mixing is carried out in a drum - type mixing device, the rotation speed is 150 rpm; the mixing time is 4 h) and dried for 12 h to obtain the printing raw material;

[0060] Step 4: Establish a 3D model on the computer according to the part shape; slice and layer the model using software and import it into the laser printing system; through the numerical control system, use a focused high-energy laser beam to reciprocally scan the printing material in step (3) layer by layer along a determined scanning path, layer by layer stacking until a 3D part is formed;

[0061] Step 5: A high-entropy tungsten heavy alloy material sample formed by laser printing, specifically, the laser printing is laser direct energy deposition; control the process parameters during laser printing: the laser power of the bottom layer is 1000W, the scanning speed is 3.3mm / s, the powder feeding speed is 6g / min, the scanning spacing is 1.5mm, the height of each layer is 0.5mm, the laser spot is 1mm, the interlayer angle is 90°, and the interlayer cooling time is 30s; the laser power during the top layer printing is 900W, the scanning speed is 3.3mm / s, the powder feeding speed is 6g / min, the scanning spacing is 1.5mm, the height of each layer is 0.5mm, the laser spot is 1mm, the interlayer angle is 90°, and the interlayer cooling time is 30s;

[0062] After testing, the microstructure of the prepared material sample shows a dual-structure organization. The microhardness at the core-shell structure is 825.6HV 1.0 , and the wear rate is 3.77×10 -5 mm 3 , and the microhardness at the dendrite structure is 620.3HV 1.0 , and the wear rate is 6.7×10 -6 mm 3 / N·m.

[0063] Example 1-1

[0064] Other conditions are the same as those in Example 1, the difference is: control the process parameters during laser printing: the laser power of the bottom layer is 900W, the scanning speed is 3.3mm / s, the powder feeding speed is 6g / min, the scanning spacing is 1.5mm, the height of each layer is 0.5mm, the laser spot is 1mm, the interlayer angle is 90°, and the interlayer cooling time is 30s; the laser power of the top layer is 800W, the scanning speed is 3.3mm / s, the powder feeding speed is 6g / min, the scanning spacing is 1.5mm, the height of each layer is 0.5mm, the laser spot is 1mm, the interlayer angle is 90°, and the interlayer cooling time is 30s;

[0065] After testing, the microstructure of the prepared material sample shows a dual-structure organization. The microhardness at the core-shell structure is 672.1HV 1.0 , and the wear rate is 7.92×10 -5 mm 3 , and the microhardness at the dendrite structure is 615.6HV 1.0 , and the wear rate is 6.3×10-6 mm 3 / N·m。

[0066] Example 1-2

[0067] Other conditions are the same as those in Example 1, except that: during laser printing, the process parameters are controlled as follows: the laser power of the bottom layer is 1100W, the scanning speed is 3.3mm / s, the powder feeding speed is 6g / min, the scanning spacing is 2.0mm, the height of each layer is 0.5mm, the laser spot is 1mm, the interlayer angle is 90°, and the interlayer cooling time is 30s; the laser power of the top layer is 1000W, the scanning speed is 3.3mm / s, the powder feeding speed is 6g / min, the scanning spacing is 2.0mm, the height of each layer is 0.5mm, the laser spot is 1mm, the interlayer angle is 90°, and the interlayer cooling time is 30s;

[0068] After testing, the microstructure of the prepared material sample shows a dual-structure organization. The microhardness at the core-shell structure is 720.7HV 1.0 , and the wear rate is 1.53×10 -5 mm 3 / N·m, and the microhardness at the dendritic structure is 597.6HV 1.0 , and the wear rate is 2.5×10 -5 mm 3 / N·m。

[0069] Example 1-3

[0070] Other conditions are the same as those in Example 1, except that: during laser printing, the process parameters are controlled as follows: the laser power of the bottom layer is 1200W, the scanning speed is 3mm / s, the powder feeding speed is 6g / min, the scanning spacing is 1.5mm, the height of each layer is 1.0mm, the laser spot is 1mm, and the interlayer angle is 90°; the laser power of the top layer is 1100W, the scanning speed is 3mm / s, the powder feeding speed is 6g / min, the scanning spacing is 1.5mm, the height of each layer is 1.0mm, the laser spot is 1mm, and the interlayer angle is 90°.

[0071] After testing, the microstructure of the prepared material sample shows a dual-structure organization. The microhardness at the core-shell structure is 693.8HV 1.0 , and the wear rate is 8.4×10 -6 mm 3 , and the microhardness at the dendritic structure is 532.4HV 1.0 , and the wear rate is 3.22×10 -5 mm 3 / N·m。

[0072] Example 2

[0073] Step 1: Ball-mill and mix elemental powders of Co powder, Cr powder, Fe powder, Ni powder, and Mn powder (the particle size of each powder is 53 - 150 μm) to obtain a pre-mixed CoCrFeNiMn high-entropy alloy powder;

[0074] Among them, the molar ratio of elemental powders of Co powder, Cr powder, Fe powder, Ni powder, and Mn powder is 1:1:1:1:1; during ball-milling and mixing, the mass ratio of balls to materials is 2:1; the rotation speed for ball-milling and mixing treatment is 200 rpm; the time for ball-milling and mixing treatment is 30 min.

[0075] Step 2: Use tungsten powder as raw material A (particle size is 53 - 150 μm), and use the pre-mixed CoCrFeNiMn high-entropy alloy powder as raw material B; according to the mass ratio, raw material A: raw material B = (80:20); allocate the raw materials; then mix raw material A and raw material B evenly (the even mixing is carried out in a drum-type mixing device, the rotation speed is 150 rpm; the mixing time is 4 h) and dry for 12 h to obtain the printing raw material;

[0076] Step 4: Establish a three-dimensional model on the computer according to the part shape; use software to slice and layer the model, and import it into the laser printing system; through the numerical control system, use a focused high-energy laser beam to scan the printing raw material in step (3) layer by layer reciprocally along a determined scanning path, layer by layer stacking until a three-dimensional part is formed;

[0077] Step 5: For the high-entropy - tungsten heavy alloy material sample formed by laser printing, through the optimization of the previous process, the selected process parameters are: the laser power of the bottom layer is 900 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; the laser power of the top layer is 800 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s.

[0078] After testing, the microstructure of the prepared material sample shows a dual-structure organization. The microhardness at the core-shell structure is 678.8 HV 1.0 , and the wear rate is 5.7×10 -6 mm 3 / N·m. The microhardness at the dendritic structure is 652.5 HV 1.0 , and the wear rate is 5.4×10 -6 mm 3 / N·m.

[0079] Example 2 - 1

[0080] Other conditions are the same as those in Example 2, except that: during laser printing, the process parameters are controlled as follows: for the bottom layer, the laser power is 1000 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 7 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; for the top layer, the laser power is 900 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 7 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s.

[0081] After testing, the microstructure of the prepared material sample shows a dual-structure tissue. The microhardness at the core-shell structure is 698.3 HV 1.0 , and the wear rate is 6.7×10 -6 mm 3 / N·m. The microhardness at the dendritic structure is 673.5 HV 1.0 , and the wear rate is 5.7×10 -6 mm 3 / N·m.

[0082] Example 2-2

[0083] Other conditions are the same as those in Example 2, except that: during laser printing, the process parameters are controlled as follows: for the bottom layer, the laser power is 800 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 2.0 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; for the top layer, the laser power is 700 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 2.0 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s.

[0084] After testing, the microstructure of the prepared material sample shows a dual-structure tissue. The microhardness at the core-shell structure is 758.2 HV 1.0 , and the wear rate is 2.9×10 -5 mm 3 / N·m. The microhardness at the dendritic structure is 685.5 HV 1.0 , and the wear rate is 6.2×10 -6 mm 3 / N·m.

[0085] Example 2-3

[0086] Other conditions are the same as those in Example 2, except that: during laser printing, the process parameters are controlled as follows: the laser power of the bottom layer is 1100 W, the scanning speed is 3 mm / s, the powder feeding speed is 6 g / min, the scanning pitch is 1.5 mm, the height of each layer is 1.0 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; the laser power of the top layer is 1000 W, the scanning speed is 3 mm / s, the powder feeding speed is 6 g / min, the scanning pitch is 1.5 mm, the height of each layer is 1.0 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s.

[0087] After testing, the microstructure of the prepared material sample shows a dual-structure tissue, and the microhardness at the core-shell structure is 586.0 HV 1.0 , and the wear rate is 9.6×10 -6 mm 3 / N·m. The microhardness at the dendritic structure is 558.3 HV 1.0 , and the wear rate is 1.2×10 -5 mm 3 / N·m.

[0088] Comparative Example 1

[0089] Its conditions are the same as those in Example 1, except that:

[0090] Step 1: Ball-mill and mix Fe powder and Ni powder (the particle size of each powder is 53 - 150 μm) to obtain a nickel-iron mixed powder; the mass ratio of Ni powder to Fe powder is 7:3;

[0091] Step 2: Use tungsten powder as raw material A (particle size is 53 - 150 μm), and use the nickel-iron mixed powder obtained in step (1) as raw material B; according to the mass ratio, raw material A: raw material B = (90:10); weigh the raw materials; then mix raw material A and raw material B evenly (the even mixing is carried out in a drum-type mixing equipment with a rotation speed of 200 rpm; the mixing time is 5 h) and dry for 12 h to obtain a high-entropy tungsten heavy alloy powder;

[0092] Adopt laser printing (the printing parameters are exactly the same as those in Example 1); after testing, the microstructure of the prepared material sample shows a dendritic tissue, and the microhardness is 852.1 HV 1.0 , and the wear rate is 2.53×10 -5 mm 3 / N·m.

[0093] Comparative Example 2

[0094] Its conditions are the same as those in Example 1, except that:

[0095] Control process parameters during laser printing: the laser power of the bottom layer is 800 W, the scanning speed is 5 mm / s, the powder feeding speed is 8 g / min, the scanning spacing is 1.0 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, and the interlayer angle is 90°; the laser power of the top layer is 700 W, the scanning speed is 5 mm / s, the powder feeding speed is 8 g / min, the scanning spacing is 1.0 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, and the interlayer angle is 90°.

[0096] After testing, the microstructure of the prepared material sample shows only a core-shell structure, and its microhardness is 1089.1 HV 1.0 ; compared with Example 1, due to the lower laser power in this comparative example, the overall energy density is lower than the optimal parameters, and the high-entropy phase cannot be tightly combined with the W phase. Therefore, the sample under these parameters shows high brittleness and cannot be used for friction and wear experiments.

[0097] Comparative Example 3

[0098] Its conditions are the same as those in Example 1, except that:

[0099] Control process parameters during laser printing: the laser power of the bottom layer is 1500 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 60 s; the laser power of the top layer is 1400 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 60 s; after testing, the sample collapses and cannot be formed under these parameters.

[0100] .

Claims

1. A dual-structure high-entropy tungsten heavy alloy, characterized in that: The microstructure of the bottom tungsten dendrite region is composed of BCC phase and μ phase, and is evenly dispersed in the FCC phase matrix; the top tungsten is embedded in the FCC matrix in the form of a core-shell structure; in the double-structure high-entropy tungsten heavy alloy, the mass percentage of W is 80-90%; the high-entropy alloy contains Co, Cr, Fe, Ni and Mn.

2. A dual-structure high-entropy tungsten heavy alloy according to claim 1, characterized in that: In the double-structure high-entropy tungsten heavy alloy, the atomic ratio of Co, Cr, Fe, Ni and Mn is (0.5-1.5):(0.5-1.5):(0.5-2.0):(0.5-1.5):(0.5-1.2).

3. A preparation method of a dual-structure high-entropy tungsten heavy alloy, characterized in that, It includes the following steps: (1) Uniformly mix the raw powder of each elemental element to obtain a prefabricated mixed powder of CoCrFeNiMn high-entropy alloy; secondly, uniformly mix the W powder and the prefabricated mixed powder of CoCrFeNiMn high-entropy alloy to obtain the standby printing raw material, and vacuum dry the printing raw material. (2) Using the dried printing raw material as the object, laser printing is carried out to obtain a high-entropy tungsten heavy alloy; during laser printing, control: the power is 800-1200W, the scanning speed is 3-4mm / s, the single-layer thickness is 0.4-0.6mm, the scanning spacing is 0.8-1.2mm, the interlayer cooling is 20-40s, and the interlayer angle is 45-90°. In step (1), the atomic ratio of Co, Cr, Fe, Ni and Mn is (0.5-1.5):(0.5-1.5):(0.5-2.0):(0.5-1.5):(0.5-1.2), and the particle sizes of the W powder and the raw powder of each elemental element are all ≤150μm; based on the dry material, the mass percentage of the W powder in the standby high-entropy tungsten heavy alloy powder is 80-90%.

4. The preparation method of a dual-structure high-entropy tungsten heavy alloy according to claim 3, characterized in that: In step (1), the atomic ratio of Co, Cr, Fe, Ni and Mn is (0.9-1.1):(0.9-1.1):(0.9-1.1):(0.9-1.1):(0.9-1.1).

5. The preparation method of a dual-structure high-entropy tungsten heavy alloy according to claim 3, characterized in that: In step (1), the particle size of the spherical powder of Co, Cr, Fe, Ni and Mn is 53-150μm. In step (1), weigh the raw powder of elemental elements Co powder, Cr powder, Fe powder, Ni powder and Mn powder according to the designed ratio; then carry out ball milling and mixing treatment to obtain the prefabricated mixed powder of CoCrFeNiMn high-entropy alloy after ball milling; during ball milling, control the mass ratio of balls to materials to be 1-5:1, the rotation speed of ball milling and mixing treatment is 100-300rpm, and the time of ball milling and mixing treatment is 20-60min.

6. The preparation method of a dual-structure high-entropy tungsten heavy alloy according to claim 3, characterized in that: In step (1), the mass ratio of the W powder to the prefabricated mixed powder of CoCrFeNiMn high-entropy alloy is (80-90):(10-20).

7. The preparation method of a dual-structure high-entropy tungsten heavy alloy according to claim 3, characterized in that: In step (1), the mass ratio of the W powder to the prefabricated mixed powder of CoCrFeNiMn high-entropy alloy is 80-81:19-20 or 90-91:9-10.

8. The preparation method of a dual-structure high-entropy tungsten heavy alloy according to claim 3, characterized in that: In step (1), the rotation speed of uniform mixing is 120-180rpm, and the mixing time is 2-6h. The temperature for vacuum drying the standby powder is 60-100°C, and the heat preservation time is 250-350min.

9. The preparation method of a dual-structure high-entropy tungsten heavy alloy according to claim 3, characterized in that: In step (2), during laser printing, the power is 800 - 1200 W, the scanning speed is 3 - 4 mm / s, the single-layer thickness is 0.4 - 0.6 mm, the scanning spacing is 0.8 - 1.2 mm, the interlayer cooling time is 20 - 40 s, the interlayer angle is 90°; the laser spot is 1 mm.

10. The preparation method of a dual-structure high-entropy tungsten heavy alloy according to claim 9, characterized in that: When the molar ratio of each element in the CoCrFeNiMn high-entropy alloy prefabricated mixed powder is 1:1:1:1:1, and the mass ratio of W powder to the CoCrFeNiMn high-entropy alloy prefabricated mixed powder is 90:10, control the process parameters during laser printing: the bottom layer laser power is 1000 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; during the top layer printing, the laser power is 900 W, the scanning speed is 3.3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; or control the process parameters during laser printing: the bottom layer laser power is 900 W, the scanning speed is 3 mm / s, the powder feeding speed is 6.5 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; during the top layer printing, the laser power is 800 W, the scanning speed is 3 mm / s, the powder feeding speed is 6.5 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°; the interlayer cooling time is 30 s. When the CoCrFeNiMn high-entropy alloy prefabricated mixed powder is composed of a molar ratio of each element of 1:1:1:1:1, and the mass ratio of W powder to the mixed powder is 80:20, control the process parameters during laser printing: the bottom layer laser power is 900 W, the scanning speed is 3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s; during the top layer printing, the laser power is 800 W, the scanning speed is 3 mm / s, the powder feeding speed is 6 g / min, the scanning spacing is 1.5 mm, the height of each layer is 0.5 mm, the laser spot is 1 mm, the interlayer angle is 90°, and the interlayer cooling time is 30 s.

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