Preparation method of high-hardness nbmotaw alloy and use thereof

Abstract

The application relates to the technical field of refractory alloy preparation, and particularly discloses a preparation method and application of a high-hardness NbMoTaW alloy, which comprises the following steps: S1, raw material preparation: selecting NbMoTaW alloy powder as raw material and weighing a certain mass for standby; S2, powder pretreatment: putting the weighed NbMoTaW alloy powder in a planetary ball mill and a hydrogen furnace in sequence for pretreatment; S3, hot-pressing sintering; and S4, microhardness testing. The application breaks through the existing technical cognition, selects coarse alloy powder with a particle size of 15-43 microns at a low cost, discards the second phase addition, removes the powder oxidation layer by using the hydrogen furnace pretreatment, improves the grain boundary state, refines the grains by conventional ball milling treatment, generates lattice distortion, and the synergistic effect of the two can significantly improve the sintering activity of the powder; and then the powder is fully densified by optimizing the hot-pressing sintering parameters, so that a uniform and fine alloy organization is formed.

Description

Technical Field

[0001] This invention belongs to the field of refractory alloy preparation technology, specifically relating to a method for preparing a high-hardness NbMoTaW alloy and its applications. Background Technology

[0002] Refractory high-entropy alloys, with their unique multi-principal-element alloy design concept, exhibit inherent characteristics such as high-entropy effect, lattice distortion effect, and slow diffusion effect. This allows them to maintain a stable microstructure and excellent mechanical properties even in ultra-high temperature environments, making them a core candidate material to replace traditional nickel-based superalloys. Among them, the NbMoTaW refractory high-entropy alloy, composed of refractory elements such as Nb, Mo, Ta, and W, is a typical representative of this system. It forms a stable body-centered cubic single-phase solid solution structure with a melting point exceeding 3000℃. Even under extreme high-temperature compression conditions at 1600℃, it can still maintain a yield strength of over 400MPa, far exceeding the service strength of Inconel 718 alloy at 1000℃. It shows irreplaceable application potential in aerospace, advanced energy, and other fields. Microhardness is a key indicator that determines its wear resistance and service life. Currently, existing NbMoTaW alloy preparation technologies have the following shortcomings: First, in terms of raw material selection, fine powders with a particle size of 1~10μm are mostly used (such as the patent with patent number CN113373363A). The preparation cost of fine powders is high and they are difficult to obtain, which is not conducive to large-scale production. Second, in terms of process route, existing preparation processes without the addition of a second phase generally result in lower alloy hardness. The addition of second phase particles is required to significantly improve the alloy hardness, which leads to complex processes and further increases in production costs. Moreover, the addition of second phase particles may affect the overall uniformity of the alloy, making it difficult to meet the application requirements of high wear resistance and high load scenarios. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a high-hardness NbMoTaW alloy, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a high-hardness NbMoTaW alloy includes the following steps: S1. Raw material preparation: Select NbMoTaW alloy powder as raw material and weigh out a certain mass for later use. S2. Powder pretreatment: The NbMoTaW alloy powder weighed in S1 is placed into a planetary ball mill and a hydrogen furnace for pretreatment. S3. Hot pressing sintering: The alloy powder pretreated in S2 is pressed into shape by hot pressing sintering equipment to obtain high-hardness NbMoTaW alloy. S4. Microhardness test: The high-hardness NbMoTaW alloy prepared in S3 was polished and then subjected to microhardness test by a hardness tester at room temperature.

[0005] Preferably, the NbMoTaW alloy powder in S1 has a particle size of 15~43μm.

[0006] Preferably, the planetary ball mill in S2 has a rotational speed of 400~500 rpm / min and a ball milling time of 6~14 h.

[0007] Preferably, the grinding jar and grinding balls of the planetary ball mill in S2 are both made of zirconium oxide.

[0008] Preferably, the gas used for pretreatment in the S2 hydrogen furnace is a mixture of hydrogen and argon, wherein the hydrogen content is 10%~100%, the heating rate is 5~10℃ / min, the pretreatment temperature is 600~800℃, and the holding time is 0.5~2.5h.

[0009] Preferably, the heating rate of the hot pressing sintering equipment in S3 is 5~20℃ / min, the sintering pressure is 20~100MPa, the sintering temperature is 1500~1700℃, and the holding time is 1~3h.

[0010] Preferably, the loading load of the microhardness testing equipment in S4 is 0.5~20kg, and the loading time is 15~30s. To ensure the accuracy of the measurement, each alloy sample has more than 5 test points, and the average value is calculated.

[0011] Preferably, the high-hardness NbMoTaW alloy prepared according to the above method is used in aerospace ultra-high temperature components, nuclear reactor radiation-resistant components, high-temperature wear-resistant molds, and heat-resistant structural components under extreme conditions.

[0012] Compared with the prior art, the beneficial effects of the present invention are: This invention breaks through existing technological understanding by using low-cost coarse alloy powder with a particle size of 15~43μm, eliminating the addition of a second phase, and using a hydrogen furnace pretreatment to remove the powder oxide layer and improve the grain boundary state, followed by conventional ball milling to refine the grains and generate lattice distortion. The synergistic effect of these two processes significantly improves the sintering activity of the powder. Furthermore, by optimizing the hot pressing sintering parameters, the powder is fully densified to form a uniform and fine alloy structure, thereby significantly improving the alloy hardness without adding a second phase. This solves many pain points of existing technologies, such as high cost of fine powder, complex second phase processing, and insufficient hardness. Attached Figure Description

[0013] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a bar chart comparing the hardness of the alloy under different pretreatment methods according to the present invention. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Example 1 (Optimal Example: Ball Milling + Hydrogen Calcination): Please see Figures 1-2 As shown, a method for preparing a high-hardness NbMoTaW alloy includes: 1. Raw material preparation: Select NbMoTaW alloy powder with a particle size of 15~43μm, weigh 10g of powder for later use; 2. Powder pretreatment: The above powder is placed in a planetary ball mill and ball-milled at a speed of 470 rpm / min for 10 hours. After ball milling, the particle size is 811 nm according to BET test. The ball-milled powder is then placed in a hydrogen furnace, and a mixture of hydrogen and argon gas is introduced, with a hydrogen content of 20%. The heating rate is 10℃ / min, and the temperature is raised to 800℃ and held for 1 hour to remove the surface oxide layer. 3. Hot pressing sintering: The pretreated powder is loaded into a hot pressing sintering mold and placed into a hot pressing sintering equipment. The sintering pressure is set to 90MPa, the heating rate is 10℃ / min, and the temperature is raised to 1600℃. After holding at the temperature for 2 hours, the high-hardness NbMoTaW alloy block is taken out after sintering is completed and naturally cooled to room temperature. 4. Microhardness Test: The prepared high-hardness NbMoTaW alloy bulk was subjected to microhardness testing, and the measured microhardness was 1032±14 HV (e.g., ...). Figure 2 The No. 4 alloy sample has a uniform microstructure, no obvious defects, and excellent wear resistance, making it suitable for wear-resistant components for hot-end aerospace applications.

[0016] Comparative Example 1 (Ball mill + tube furnace sintering): 1. Raw material preparation: Select NbMoTaW alloy powder with a particle size of 15~43μm, weigh 10g of powder for later use; 2. Powder pretreatment: The above powder is placed in a planetary ball mill and ball-milled at a speed of 470 rpm / min for 10 hours. After ball milling, the powder is placed in a tube furnace and heated to 800℃ at a heating rate of 10℃ / min, and held at that temperature for 1 hour. 3. Hot pressing sintering: The pretreated powder is loaded into a hot pressing sintering mold, placed into a hot pressing sintering equipment, and the sintering pressure is set to 90MPa, the heating rate is 10℃ / min, the temperature is raised to 1600℃, and then held for 2 hours. After sintering is completed, the alloy block is naturally cooled to room temperature and taken out. 4. Microhardness Test: The prepared alloy block was subjected to microhardness testing, and the measured microhardness was 719±7 HV (e.g., ...). Figure 2 (Sample No. 3 of alloy).

[0017] Comparative Example 2 (ball milling only): 1. Raw material preparation: Select NbMoTaW alloy powder with a particle size of 15~43μm, weigh 10g of powder for later use; 2. Powder pretreatment: Place the above powder into a planetary ball mill and ball mill it at a speed of 470 rpm / min for 10 hours; 3. Hot pressing sintering: The pretreated powder is loaded into a hot pressing sintering mold, placed into a hot pressing sintering equipment, and the sintering pressure is set to 90MPa, the heating rate is 10℃ / min, the temperature is raised to 1600℃, and then held for 2 hours. After sintering is completed, the alloy block is naturally cooled to room temperature and taken out. 4. Microhardness Test: The prepared alloy block was subjected to microhardness testing, and the measured microhardness was 636±22 HV (e.g., ...). Figure 2 (Middle 2# alloy sample).

[0018] Comparative Example 3 (without pretreatment): 1. Raw material preparation: Select NbMoTaW alloy powder with a particle size of 15~43μm, weigh 10g of powder for later use; 2. Hot pressing sintering: The powder is loaded into the hot pressing sintering mold, placed into the hot pressing sintering equipment, the sintering pressure is set to 90MPa, the heating rate is 10℃ / min, the temperature is raised to 1600℃, and then held for 2 hours. After sintering is completed, the alloy block is naturally cooled to room temperature and taken out. 3. Microhardness test: The prepared alloy block was subjected to microhardness testing, and the measured microhardness was 256±8 HV (e.g., ...). Figure 2 (Middle 1# alloy sample).

[0019] The above experimental comparison shows that the high-hardness NbMoTaW alloy prepared by this invention has high hardness, uniform alloy structure, no obvious defects, and excellent wear resistance. It is suitable for applications such as aerospace hot-end wear-resistant parts and wear-resistant molds where high alloy hardness and high-temperature resistance are required.

[0020] This invention solves the problems of high cost and difficulty in obtaining fine powder raw materials in the preparation of existing NbMoTaW alloys; 2. This invention addresses the problems of complex processes, high costs, and poor alloy uniformity caused by the need to add second-phase particles to improve hardness in existing technologies. It breaks through the hardness bottleneck without the addition of a second phase, achieving stable preparation of NbMoTaW alloy with high hardness, thus meeting the requirements of high wear resistance and high temperature resistance applications.

[0021] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-hardness NbMoTaW alloy, characterized in that, Includes the following steps: S1. Raw material preparation: Select NbMoTaW alloy powder as raw material and weigh out a certain mass for later use. S2. Powder pretreatment: The NbMoTaW alloy powder weighed in S1 is placed into a planetary ball mill and a hydrogen furnace for pretreatment. S3. Hot pressing sintering: The alloy powder pretreated in S2 is pressed into shape by hot pressing sintering equipment to obtain high-hardness NbMoTaW alloy. S4. Microhardness test: The high-hardness NbMoTaW alloy prepared in S3 was polished and then subjected to microhardness test by a hardness tester at room temperature. The particle size of the NbMoTaW alloy powder in S1 is 15~43μm; The gas used for pretreatment in the S2 hydrogen furnace is a mixture of hydrogen and argon, with a hydrogen content of 10% to 100%, a heating rate of 5 to 10 °C / min, a pretreatment temperature of 600 to 800 °C, and a holding time of 0.5 to 2.5 h. The heating rate of the hot pressing sintering equipment in S3 is 5~20℃ / min, the sintering pressure is 20~100MPa, the sintering temperature is 1500~1700℃, and the holding time is 1~3h.

2. The method for preparing a high-hardness NbMoTaW alloy according to claim 1, characterized in that: The planetary ball mill in S2 has a rotation speed of 400~500 rpm / min and a ball milling time of 6~14 h.

3. The method for preparing a high-hardness NbMoTaW alloy according to claim 2, characterized in that: The grinding jar and grinding balls of the planetary ball mill in S2 are both made of zirconium oxide.

4. The method for preparing a high-hardness NbMoTaW alloy according to claim 3, characterized in that: The loading load of the hardness tester in S4 is 0.5~20kg, and the loading time is 15~30s. To ensure the accuracy of the measurement, there are more than 5 test points for each alloy sample, and the average value is calculated.

5. The use of the high-hardness NbMoTaW alloy prepared by the method according to any one of claims 1-4, characterized in that: The high-hardness NbMoTaW alloy is used in heat-resistant structural components for extreme working conditions.

6. The use of the high-hardness NbMoTaW alloy prepared according to claim 5, characterized in that: The extreme-condition heat-resistant structural components include aerospace ultra-high temperature components, nuclear reactor radiation-resistant components, and high-temperature wear-resistant molds.

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