A high-temperature resistant multi-element high-entropy alloy solder and its preparation method

Abstract

This invention belongs to the technical field of welding materials and discloses a high-temperature resistant multi-element high-entropy alloy brazing filler metal and its preparation method. By mass fraction, it comprises the following components: Co 15%–25%, Ni 15%–25%, Cr 15%–25%, Fe 15%–25%, Cu 15%–25%, Mn 0.1–3%, Si 0.1–6%, B 0.1–5%, Sc 0.5–0.9%, and Y 0.1–1%. The preparation method of this invention is simple to operate, low in cost, highly efficient, and highly adaptable, showing great application potential. The high-entropy alloy brazing filler metal of this invention can be used in high-temperature, high-pressure, and corrosion-resistant environments after welding.

Description

Technical Field

[0001] This invention relates to the technical field of welding materials, and in particular to a high-temperature resistant multi-element high-entropy alloy brazing filler metal and its preparation method. Background Technology

[0002] High-entropy alloys (HEAs) are alloys formed by mixing five or more elements in equal or approximately equal amounts. They possess better strength-to-weight ratio, fracture resistance, tensile strength, corrosion resistance, and oxidation resistance. As brazing filler metals, they are used for brazing high-temperature alloys, cemented carbides, and other materials, enabling the production of heterogeneous welded joints with excellent microstructure and properties. The connection between cemented carbides and steel is typically achieved through brazing or sintering.

[0003] With the development of high thrust-to-weight ratio aero engines, some key engine components employ complex connection structures between shell steel and localized hard alloy contact surfaces. This meets the demands of next-generation high thrust-to-weight ratio engines for novel high-temperature resistant structural materials, as well as the requirements for high hardness, high wear resistance, and high-temperature resistance at the connection points. For the connection of complex and precise dual-alloy structures, brazing is currently the most commonly used method.

[0004] The selection of brazing filler metal is particularly critical in the brazing process. During welding, the filler metal wets the base material and forms a solid solution or similar structure with the base material to achieve a tight bond between the welding materials. However, with the rapid development of high thrust-to-weight ratio engines in recent years, the existing high-temperature brazing materials can no longer meet the requirements. Therefore, it is necessary to develop new high-temperature filler metals with better performance to solve the problem of connecting cemented carbide and steel in high thrust-to-weight ratio engines. Summary of the Invention

[0005] This invention provides a high-temperature resistant multi-element high-entropy alloy brazing filler metal and its preparation method. The brazing filler metal prepared has a welding temperature of 980-1050℃, which exceeds the operating temperature of brazing filler metals currently on the market. It can effectively solve the problem of connection and repair of high-temperature alloy parts under harsh conditions and has important application value.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A high-temperature resistant multi-element high-entropy alloy brazing filler metal comprises the following components by mass fraction: Co 15%–25%, Ni 15%–25%, Cr 15%–25%, Fe 15%–25%, Cu 15%–25%, Mn 0.1–3%, Si 0.1–6%, B 0.1–5%, Sc 0.5–0.9%, and Y 0.1–1%.

[0008] Furthermore, by mass fraction, it includes the following components: Ni 20%, Cr 16%, Fe 16%, Cu 16%, Mn 1%, Si 5%, B 3%, Sc 0.5%, Y 0.3%, and Co balance.

[0009] Furthermore, by mass fraction, it includes the following components: Ni 20%, Cr 16%, Fe 16%, Cu 16%, Mn 1%, Si 5%, B 3%, Sc 0.7%, Y 0.3%, and Co balance.

[0010] Furthermore, by mass fraction, it includes the following components: Ni 20%, Cr 16%, Fe 16%, Cu 16%, Mn 1%, Si 5%, B 3%, Sc 0.9%, Y 0.3%, and Co balance.

[0011] A method for preparing a high-temperature resistant multi-element high-entropy alloy solder as described above includes the following steps:

[0012] (1) Ingredients

[0013] Mix according to the specified proportions;

[0014] (2) Smelting

[0015] The alloy ingot is obtained by sequentially vacuuming, melting multiple times, and cooling.

[0016] Furthermore, the raw materials for each component are all particles with a purity of 99.99%-100%. The non-consumable arc melting furnace used for melting is evacuated to below 4 Pa, and then filled with argon gas with a purity of 99.99% until the pressure reaches -0.05 MPa. Melting is carried out 3-5 times in sequence, and finally the alloy ingot is obtained by cooling at room temperature.

[0017] The above-described application of brazing filler metal in the preparation of high-temperature alloy materials.

[0018] Furthermore, the preparation method is characterized by brazing.

[0019] Furthermore, the brazing temperature is 993.7℃~1001.5℃.

[0020] Next, the clamped base material and brazing filler metal are placed into a vacuum brazing furnace, and the vacuum in the furnace is evacuated to 100°C. - 3 Pa, then turn on the heating system to raise the temperature in the furnace at 20℃ / min to 1001.5℃, hold for 10 minutes, and finally cool with the furnace to room temperature to obtain the brazed joint; the base material is set as YG20 cemented carbide and 45# steel.

[0021] The beneficial technical effects of this invention are as follows:

[0022] The high-entropy alloy brazing filler metal of this invention does not contain precious metals such as Au and Pd, and is inexpensive. The newly added rare earth element scandium can increase the recrystallization temperature of the alloy by 150-200°C, and significantly improve its high-temperature strength, structural stability, weldability and corrosion resistance, while avoiding the embrittlement phenomenon that easily occurs during long-term operation at high temperatures. The newly added rare earth element yttrium can refine the as-cast grains of the brazing filler metal alloy, refine the secondary dendrite spacing, and improve the distribution and morphology of the second phase.

[0023] The high-entropy alloy brazing filler metal of this invention is suitable for brazing cemented carbide and steel. Under the combined effect of high-entropy effect and hysteresis diffusion effect, it can effectively suppress the formation of catalytic IMC at the interface, thereby improving the quality of the weld joint and enhancing its mechanical properties. The resulting weld joint meets the high-temperature requirements of 600-800℃ and the bending strength can reach 408MPa. At the same time, this brazing filler metal has good hardness, corrosion resistance and high-temperature resistance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the finished product obtained by melting the multi-element high-entropy alloy brazing filler metal prepared in this invention;

[0025] Figure 2 This is a schematic diagram of X-ray diffraction of the multi-element high-entropy alloy brazing filler metal prepared in this invention;

[0026] Figure 3 This is a schematic diagram of the DSC curve of the multi-element high-entropy alloy solder prepared in this invention;

[0027] Figure 4 This is a schematic diagram showing the bending strength of a welded joint obtained by welding using the multi-element high-entropy alloy brazing filler metal prepared in this invention. Detailed Implementation

[0028] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings and preferred embodiments.

[0029] Example 1

[0030] This embodiment provides a multi-element high-entropy alloy brazing filler metal with the following composition by mass percentage: Co balance, Ni 20%, Cr 16%, Fe 16%, Cu 16%, Mn 1%, Si 5%, B 3%, Sc 0.5%, Y 0.3%, and the sum of the mass percentages of each component is 100wt%.

[0031] In this embodiment, the raw materials corresponding to the alloying elements are all single-element particles with a purity greater than 99.9%.

[0032] The specific preparation method of the high-entropy alloy brazing filler metal in this embodiment is as follows:

[0033] Step 1: Ingredients

[0034] Weigh the required raw materials for smelting according to the mass percentage of the brazing filler metal;

[0035] Step 2: Melting

[0036] A vacuum non-consumable arc furnace (model DHL500) was used to evacuate the material to below 4 Pa. Then, 99.99% pure argon gas was introduced until the gauge pressure reached -0.05 MPa. The current of the vacuum non-consumable arc furnace was set to 400-600 A, and an electromagnetic stirrer was turned on to stir until the material was completely melted. The whole process took about 3 minutes. After melting, the material was cooled to room temperature and a sample was taken to obtain a disc-shaped alloy ingot. The high-entropy alloy ingot was then reversed and the above operation was repeated. After melting four times, the final brazing filler metal ingot was obtained.

[0037] Phase analysis of the newly refined high-entropy alloy brazing filler metal was performed using X-ray diffraction (XRD). The filler metal was cut into 15×15×6mm sheets using wire cutting, and after grinding to remove the oxide layer, cleaning, and drying, an X′Pert Pro X-ray diffractometer (PA Nalytical, Netherlands) was used to obtain the diffraction pattern of the material, as shown below. Figure 2 As shown in the XRD phase diagram, further comparison of the characteristic peaks of the diffraction pattern with the standard card revealed that the main phase of the prepared solder is Cu. 0.48 Co 0.52 Fe3B and B2Fe 15 The presence of Si3 and other phases gives the brazing filler metal excellent wear resistance and corrosion resistance.

[0038] Next, the melting temperature of the solder was tested using thermogravimetric analysis-differential scanning calorimetry (TG-DSC) to measure and compare the results. The equipment used in this test was an SDT650 simultaneous thermal analyzer (TA Instruments, USA). The parameters set during the test were: temperature range 20–1100℃, heating rate 20℃ / min, and argon as the protective gas. The results are as follows: Figure 3 The DSG curves shown indicate that the melting temperature of the solder in Example 1 was 981.5°C.

[0039] The multi-element high-entropy alloy brazing filler metal prepared in this embodiment is used for vacuum brazing of cemented carbide and steel. The specific brazing method is as follows:

[0040] The brazing alloy master ingot was cut into 40mm×4mm thin slices with a thickness of 0.5mm using wire cutting. The thin slices were then ground and polished to obtain the high-entropy alloy brazing alloy thin slices used in the experiment.

[0041] Polish the surfaces of the cemented carbide YG20 and 45# steel to be welded, and put the parts to be welded into an ultrasonic cleaner for cleaning. After cleaning, put them into a blower for air drying.

[0042] A 40mm×4mm×0.5mm high-entropy alloy brazing filler sheet is assembled between the base materials to be welded and fixed thereon;

[0043] The multi-functional vacuum brazing furnace (KJL-1) from Beijing Huaxiang Electric Furnace Technology Co., Ltd. was used for vacuum welding of YG20 cemented carbide and 45# steel. The process involved placing the clamped base material and brazing filler metal into the vacuum brazing furnace, and then evacuating the furnace to a vacuum level of 10. -3 Pa, then turn on the heating system, and the temperature in the brazing furnace is increased at 20℃ / min to 1001.5℃, held for 10min, and then cooled to room temperature with the furnace to obtain the brazed joint.

[0044] The welded joint was subjected to a bending strength test. The welded joint was cut into strips of 80×4×3mm. The test procedure was conducted according to GB / T232-2010 "Metallic Materials - Bending Test Method". Considering the influence of weld reinforcement, spatter, and wire cutting marks on the test results, the sample was sanded before the test to eliminate these influencing factors. This test used a Zwick Roell Z050 universal mechanical testing machine (Zwick Roell, Germany), with a pressure head displacement speed of 0.5mm / min and a support roller spacing of 36mm. During the test, continuous force was applied to the sample until fracture. In this embodiment, the welded joint was subjected to three bending tensile tests, labeled 1-1, 1-2, and 1-3 as follows: Figure 4 As shown in the figure, after testing, the cemented carbide YG20 and 45 obtained after brazing... # The bending strength of the steel welded joint is 220 MPa.

[0045] Example 2

[0046] This embodiment is basically the same as Embodiment 1, except that Sc is 0.7%.

[0047] Phase analysis of the newly refined high-entropy alloy brazing filler metal was performed using X-ray diffraction (XRD). The diffraction pattern of the tested material is shown below. Figure 2As shown in the XRD phase diagram, further comparison of the characteristic peaks of the diffraction pattern with the standard card revealed that the main phase of the prepared solder is Cu. 0.48 Co 0.52 FeNi3 and B2Fe 15 The presence of Si3 and other phases gives the brazing filler metal excellent wear resistance and corrosion resistance.

[0048] The melting point of the solder was measured using thermogravimetric analysis-differential scanning calorimetry (TG-DSC) and compared to obtain the following results: Figure 3 The DSC curves shown indicate that the melting temperature of the solder in Example 1 was 975.8°C.

[0049] This embodiment prepares a high-entropy alloy brazing filler metal for vacuum brazing of cemented carbide and steel. The welded joint is then subjected to bending strength testing. In this embodiment, the welded joint is subjected to three bending and tensile tests, labeled as 2-1, 2-2, and 2-3, as follows: Figure 4 As shown, the bending strength of the brazed joint between cemented carbide YG20 and 45# steel is 348 MPa, according to the test results.

[0050] Example 3

[0051] This embodiment is basically the same as Embodiment 1, except that Sc is 0.9%.

[0052] Phase analysis of the newly refined high-entropy alloy brazing filler metal was performed using X-ray diffraction (XRD). The diffraction pattern of the tested material is shown below. Figure 2 As shown in the XRD phase diagram, further comparison of the characteristic peaks of the diffraction pattern with the standard card revealed that the main phase of the prepared solder is Cu. 0.48 Co 0.52 FeNi3, Fe3B and B2Fe 15 The presence of Si3 and other phases gives the brazing filler metal excellent wear resistance and corrosion resistance.

[0053] The melting point of the solder was measured using thermogravimetric analysis-differential scanning calorimetry (TG-DSC) and compared to obtain the following results: Figure 3 The DSG curve is shown, and the melting temperature of the solder in Example 1 is 973.7℃.

[0054] This embodiment prepares a high-entropy alloy brazing filler metal for vacuum brazing of cemented carbide and steel. The resulting welded joint is subjected to three bending and tensile tests, labeled 3-1, 3-2, and 3-3 respectively, as follows: Figure 4 As shown, the bending strength of the brazed joint between cemented carbide YG20 and 45# steel is 408 MPa, according to the test results.

[0055] Example 4

[0056] This embodiment provides an existing multi-element high-entropy alloy brazing filler metal with the following composition by mass percentage: Co 20%, Ni 20%, Cr 20%, Fe 20%, Cu 20%, and the sum of the mass percentages of each component is 100wt%.

[0057] Phase analysis of existing high-entropy alloy solders was performed using X-ray diffraction (XRD). The main phase of the existing high-entropy alloy solders was Cu. 0.48 Co 0.52 It is FeNi3. Next, the melting temperature of the existing high-entropy alloy brazing filler metal was tested. The melting point of the filler metal was measured to be 1140℃ using thermogravimetric-differential scanning calorimetry (TG-DSC).

[0058] This embodiment uses a multi-element high-entropy alloy brazing filler metal for vacuum brazing of cemented carbide and 45... # The specific brazing method for welding steel is as follows:

[0059] The brazing alloy master ingot was cut into 40mm×4mm thin slices with a thickness of 0.5mm using wire cutting. The thin slices were then ground and polished to obtain the high-entropy alloy brazing alloy thin slices used in the experiment.

[0060] Polish the surface of the base material to be welded, and put the workpiece into an ultrasonic cleaner for cleaning. After cleaning, put it into a blower for air drying.

[0061] A 40mm×4mm×0.5mm high-entropy alloy brazing filler sheet is assembled between the base materials to be welded and fixed thereon;

[0062] Using the multi-functional vacuum brazing furnace (KJL-1) from Beijing Huaxiang Electric Furnace Technology Co., Ltd., YG20 cemented carbide was brazed with 45... # Vacuum welding of steel involves the following process: placing the clamped base material and brazing filler metal into a vacuum brazing furnace, and then evacuating the furnace to a vacuum level of 10°C. -3 Pa, then turn on the heating system, and the temperature in the brazing furnace is increased at 20℃ / min to 1160℃, held for 10min, and then cooled to room temperature with the furnace to obtain the brazed joint.

[0063] The welded joint was subjected to a bending strength test. The welded joint was cut into strips of 80×4×3mm, and the test procedure was conducted according to GB / T232-2010 "Metallic Materials - Bending Test Method". Considering the influence of weld reinforcement, spatter, and wire cutting marks on the test results, the sample was sanded before the test to eliminate these influencing factors. This test used a Zwick Roell Z050 universal mechanical testing machine (Zwick Roell, Germany), with a pressure head displacement speed of 0.5mm / min and a support roller spacing of 36mm. During the test, continuous force was applied to the sample until fracture. The bending strength of the brazed joint was measured to be 216MPa.

[0064] The performance of the high-entropy alloy brazing filler metals and post-weld joints obtained in Examples 1 to 4 was tested, and the results are shown in the table below.

[0065]

[0066] This invention prepares high-entropy alloy brazing filler metal via a melting method, ensuring uniform mixing and reaction of all elements. The resulting sheet-like metal facilitates better control of filler metal dosage during welding. The multi-element high-entropy alloy brazing filler metal of this invention primarily uses cobalt, chromium, nickel, iron, and copper as its main matrix, and contains appropriate amounts of boron, manganese, and silicon. It can be used in high-temperature environments. Chromium is an indispensable element in high-temperature alloys, improving the high-temperature performance and oxidation resistance of the high-entropy alloy brazing filler metal. Nickel is a major austenite-forming element and also a forming element of the strengthening phase γ′, mainly segregating into the γ′ phase to stabilize it. The γ′ phase is the most important strengthening phase in high-temperature alloys, improving the strength of the brazing filler metal. Iron strengthens the γ phase through both dispersion and precipitation strengthening. The addition of copper improves the wettability of the brazing filler metal, increasing its wettability. Adding boron promotes grain boundary segregation, reduces grain boundary defects, and increases grain boundary strength. It can significantly alter grain boundary shape, improve the plasticity of cobalt-based alloys, and enhance the wettability and deoxidation properties of the solder. The addition of silicon lowers the solder's melting point. The rare earth element scandium, with an addition of 0.5%–0.9%, increases the alloy's recrystallization temperature by 150–200°C, and significantly improves high-temperature strength, structural stability, weldability, and corrosion resistance, while preventing embrittlement that easily occurs during long-term operation at high temperatures. Adding 0.1%–1% yttrium refines the as-cast grains of the solder alloy, reduces secondary dendrite spacing, and improves the distribution and morphology of the second phase. The high-entropy alloy solder of this invention can be used in high-temperature, high-pressure, and corrosion-resistant environments after soldering.

[0067] In summary, this invention draws upon the design concept of multi-element high-entropy alloys and, considering the performance requirements and characteristics of solders, designs a CoNiCrFeCu high-entropy system solder with added rare earth element Sc. This solder further enhances the wear resistance and high-temperature resistance of traditional solders. Simultaneously, the melting point of this high-entropy alloy solder is reduced to 973.7℃, and X-ray diffraction analysis reveals that the main phase of the solder is Cu. 0.48 Co 0.52 FeNi3, Fe3B and B2Fe 15 The presence of Si3 and other phases gives the brazing filler metal excellent wear resistance and corrosion resistance. The high-entropy alloy brazing filler metal provided by this invention can achieve a high joint bending strength of 408 MPa when used for vacuum brazing of cemented carbide and steel.

[0068] The above description is merely a preferred embodiment of the present invention. The embodiments are not intended to limit the scope of protection of the present invention. Therefore, any equivalent structural changes made based on the description and drawings of the present invention should also be included within the scope of protection of the appended claims.

Claims

1. A high-temperature resistant multi-element high-entropy alloy brazing filler metal, characterized in that, By mass fraction, it includes the following components: Co 15%–25%, Ni 15%–25%, Cr 15%–25%, Fe 15%–25%, Cu 15%–25%, Mn 0.1–3%, Si 0.1–6%, B 0.1–5%, Sc 0.5–0.9%, Y 0.1–1%.

2. The high-temperature resistant multi-element high-entropy alloy brazing filler metal according to claim 1, characterized in that, The composition by mass fraction includes the following components: Ni 20%, Cr 16%, Fe 16%, Cu 16%, Mn 1%, Si 5%, B 3%, Sc 0.5%, Y 0.3%, and Co balance.

3. The high-temperature resistant multi-element high-entropy alloy brazing filler metal according to claim 1, characterized in that, The composition by mass fraction includes the following components: Ni 20%, Cr 16%, Fe 16%, Cu 16%, Mn 1%, Si 5%, B 3%, Sc 0.7%, Y 0.3%, and Co balance.

4. The high-temperature resistant multi-element high-entropy alloy brazing filler metal according to claim 1, characterized in that, The composition by mass fraction includes the following components: Ni 20%, Cr 16%, Fe 16%, Cu 16%, Mn 1%, Si 5%, B 3%, Sc 0.9%, Y 0.3%, and Co balance.

5. A method for preparing a high-temperature resistant multi-element high-entropy alloy solder according to any one of claims 1-4, characterized in that... Includes the following steps: (1) Ingredients Mix according to the specified proportions; (2) Smelting The alloy ingot is obtained by sequentially vacuuming, melting multiple times, and cooling.

6. The method for preparing the high-temperature resistant multi-element high-entropy alloy brazing filler metal according to claim 5, characterized in that: The raw materials for each component are particles with a purity of 99.99%-100%. The non-consumable arc melting furnace used for melting is evacuated to below 4Pa, and then filled with argon gas with a purity of 99.99% until the pressure reaches -0.05MPa. Melting is carried out 3-5 times in sequence, and finally the alloy ingot is obtained by cooling at room temperature.

7. The application of the brazing filler metal according to claim 1 in the preparation of high-temperature alloy materials.

8. The application according to claim 7, characterized in that, The preparation method is brazing.

9. The application according to claim 8, characterized in that, The brazing temperature is 993.7℃~1001.5℃.

10. The application according to claim 8, characterized in that, The clamped base material and brazing filler metal are placed into a vacuum brazing furnace, and the vacuum in the furnace is evacuated to 10°C. -3 Pa, then turn on the heating system to raise the temperature in the furnace at 20℃ / min to 1001.5℃, hold for 10 minutes, and finally cool with the furnace to room temperature to obtain the brazed joint; the base material is set as YG20 cemented carbide and 45# steel.

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