High-entropy alloy system high-temperature brazing filler metal and preparation method and application thereof

Abstract

The invention discloses a high-entropy alloy system high-temperature brazing filler metal and a preparation method and application thereof, and relates to the technical field of welding materials.The preparation method comprises the following steps that iron powder, cobalt powder, nickel powder, copper powder and molybdenum powder are weighed and evenly mixed, and mixed metal powder is obtained; the mixed metal powder is put into a first ball milling tank, argon is introduced, ball milling is conducted for at least 15 h, and alloyed powder is obtained; the alloyed powder is put into a mold and sintered in the hydrogen atmosphere at the temperature of 1000-1200 DEG C, and a sintered blank is obtained; the sintered briquette is crushed into particles, the particles are put into a second ball milling tank, ball milling is conducted for at least 20 h in the argon atmosphere, and high-entropy alloy powder is obtained; and weighing the high-entropy alloy powder, borax and polyvinyl alcohol, and uniformly mixing to obtain the high-entropy alloy system high-temperature brazing filler metal. The prepared high-entropy alloy system high-temperature brazing filler metal has the advantages of being good in component uniformity, high in performance stability and excellent in wettability and filling performance, and the welding quality of a brazed joint can be effectively guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of welding materials, and in particular to a high-entropy alloy high-temperature solder and a preparation method and application thereof. Background Art

[0002] High entropy alloys are considered as a high-temperature brazing material with great potential for use in extreme environments due to their multiple advantages such as high strength, high hardness, excellent corrosion resistance, good oxidation resistance, good thermal stability, and potential low-temperature toughness. High-entropy alloy-based high-temperature brazing materials usually include at least five metal elements. Their unique composition design forms a complex solid solution or intermetallic compound structure inside the alloy, thus giving them the above-mentioned excellent properties. These characteristics make high-entropy alloy-based high-temperature brazing materials have broad application prospects in aerospace, nuclear energy industry, high-temperature equipment and other fields.

[0003] Generally, mechanical alloying is used to produce high-entropy alloy high-temperature brazing filler metals. It does not require a melting process and can prepare alloys that are difficult to melt. However, it is difficult to obtain a uniform distribution of components when using mechanical alloying to produce high-entropy alloy high-temperature brazing filler metals. This not only reduces the performance stability of the high-entropy alloy high-temperature brazing filler metals, but also affects the wettability and filling properties of the high-entropy alloy high-temperature brazing filler metals, resulting in reduced welding quality of the brazed joints. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art. The present invention provides a high-entropy alloy high-temperature brazing filler metal and a preparation method and application thereof. Through a specific metal powder ratio, a two-step ball milling process, a high-temperature sintering step and the addition of auxiliary materials, the prepared high-entropy alloy high-temperature brazing filler metal has the advantages of good composition uniformity, high performance stability, excellent wettability and filling properties, and can effectively ensure the welding quality of the brazed joint.

[0005] The present invention provides a method for preparing a high-entropy alloy high-temperature solder, comprising the following steps:

[0006] S1. According to the first weight ratio, weigh 1 to 2 parts of iron powder, 1 to 2 parts of cobalt powder, 1 to 2 parts of nickel powder, 5 to 6 parts of copper powder and 0.3 to 0.8 parts of molybdenum powder, mix them evenly to obtain a mixed metal powder;

[0007] S2, placing the mixed metal powder into a first ball mill, filling it with argon gas, and ball milling for at least 15 hours to obtain alloyed powder;

[0008] S3, placing the alloyed powder into a mold, and sintering it in a hydrogen atmosphere at 1000-1200° C. to obtain a sintered compact;

[0009] S4, crushing the sintered compact into particles, placing the particles into a second ball mill, and ball milling the particles in an argon atmosphere for at least 20 hours to obtain a high entropy alloy powder;

[0010] S5. According to the second weight proportion, weigh 6 to 12 parts of the high entropy alloy powder, 0.3 to 0.6 parts of borax and 0.1 to 0.3 parts of polyvinyl alcohol, mix them evenly, and obtain a high entropy alloy high-temperature brazing material.

[0011] Specifically, the particle size range of the iron powder is 40-50 μm, the particle size range of the cobalt powder is 40-50 μm, the particle size range of the nickel powder is 40-50 μm, the particle size range of the copper powder is 60-70 μm, and the particle size range of the molybdenum powder is 10-20 μm.

[0012] Specifically, in step S2, the first grinding balls and the mixed metal powder are placed in the first ball milling tank at a ball-to-material ratio of 10 to 20:1 for ball milling;

[0013] In step S4, the second grinding balls and the sintered compact crushed into particles are placed in the second ball milling jar at a ball-to-material ratio of 40 to 50:1 for ball milling.

[0014] Specifically, the first grinding ball includes a first chrome steel ball with a diameter of 5 mm, a second chrome steel ball with a diameter of 10 mm, and a third chrome steel ball with a diameter of 15 mm, and the number ratio of the first chrome steel ball, the second chrome steel ball, and the third chrome steel ball is 3:2:1;

[0015] The second grinding ball includes a first tungsten carbide ball with a diameter of 2 mm, a second tungsten carbide ball with a diameter of 10 mm, and a third tungsten carbide ball with a diameter of 20 mm. The quantity ratio of the first tungsten carbide ball, the second tungsten carbide ball and the third tungsten carbide ball is 5:3:1.

[0016] Specifically, the volume of the first ball mill is 1000-2000 mL, and the loading amount of the first ball mill is one third of the volume;

[0017] The volume of the second ball mill is 3000-4000 mL, and the loading amount of the second ball mill is one third of the volume.

[0018] Specifically, the first ball mill is placed in a horizontal planetary ball mill, and ball milled at a rotation speed of 900 to 1000 rpm and a revolution speed of 200 to 300 rpm;

[0019] The second ball milling jar is placed in a vibrating ball mill, and ball milling is performed at a vibration frequency of 23 to 30 Hz and a vibration amplitude of 3 to 5 mm.

[0020] Specifically, in step S3, the sintering time is 30 to 60 minutes.

[0021] The present invention also provides a high entropy alloy-based high-temperature solder, which is prepared by the high entropy alloy-based high-temperature solder preparation method.

[0022] The present invention also provides an application of the high entropy alloy high temperature brazing filler metal in welding and repairing a broken long shaft, comprising the following steps:

[0023] Flattening the fracture surface of the first broken shaft segment to form a first plane; forming a first chamfer at the edge of the first plane, and forming a first connecting hole at the center of the first plane;

[0024] Flattening the fracture surface of the second broken shaft segment to form a second plane; forming a second chamfer at the edge of the second plane, and forming a second connecting hole at the center of the second plane;

[0025] Inserting two ends of the connecting shaft into the first connecting hole and the second connecting hole respectively, with a welding gap between the first plane and the second plane, and the welding gap exposes a portion of the connecting shaft;

[0026] The high-entropy alloy high-temperature brazing material is evenly placed around the connecting shaft at the opening of the first connecting hole, and brazing is performed by using a flame as a heat source to form a first weld in the welding interval;

[0027] The high-entropy alloy high-temperature brazing material is evenly placed around the connecting shaft at the opening of the second connecting hole, and brazing is performed by using a flame as a heat source to form a second weld in the welding interval;

[0028] Overlay welding is performed from the welding interval until the first chamfer and the second chamfer are covered to form a main weld.

[0029] Specifically, the first connection hole and the second connection hole are coaxial, the depths of the first connection hole and the second connection hole are both 50-100 mm, and the diameters of the first connection hole and the second connection hole are both 20-30 mm;

[0030] The width of the welding interval ranges from 10 to 20 mm;

[0031] The sizes of the first chamfer and the second chamfer are equal, and the sizes of the first chamfer and the second chamfer are both C5-C10.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] Iron powder, cobalt powder, nickel powder, copper powder and molybdenum powder are matched according to specific weight proportions and mixed evenly, which is beneficial to improving the uniformity of the composition distribution of the high entropy alloy formed during the subsequent ball milling process on the one hand, and is beneficial to promoting the metal powder to easily achieve atomic level alloying between elements during the subsequent ball milling process on the other hand; the first ball milling process is carried out under argon protection to prevent the metal powder from oxidizing, and at the same time, the metal powder is fully alloyed through long-term ball milling; the sintering process is carried out in a high-temperature hydrogen atmosphere, which not only helps to remove oxide impurities, but also helps to promote the bonding of metal powders, further improve the alloying level, and form a dense microstructure, thereby effectively improving its performance stability; the crushing and re-ball milling steps further refine the alloy powder, which can significantly improve its uniformity and activity, thereby effectively improving the performance stability, wettability and filling property of the high entropy alloy powder; finally, the high entropy alloy powder is mixed with borax and polyvinyl alcohol according to specific weight proportions, and the obtained high entropy alloy high-temperature solder has the advantages of good composition uniformity, high performance stability, excellent wettability and filling property, and can effectively guarantee the welding quality of the brazed joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 1 is a schematic flow chart of a method for preparing a high-entropy alloy high-temperature brazing filler metal in an embodiment of the present invention;

[0036] Figure 2 It is a schematic diagram of the cross-sectional structure of a broken long axis repaired by welding in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] The present invention provides a method for preparing a high-entropy alloy high-temperature solder. Figure 1 The schematic diagram of the process of preparing a high entropy alloy high temperature brazing material in an embodiment of the present invention is shown, comprising the following steps:

[0040] S1. According to the first weight ratio, weigh 1 to 2 parts of iron powder, 1 to 2 parts of cobalt powder, 1 to 2 parts of nickel powder, 5 to 6 parts of copper powder and 0.3 to 0.8 parts of molybdenum powder, mix them evenly to obtain a mixed metal powder;

[0041] The melting point of iron is 1538℃, the melting point of cobalt is 1495℃, the melting point of nickel is 1455℃, the melting point of copper is 1084.6℃, and the melting point of molybdenum is 2623℃.

[0042] Iron powder, cobalt powder, nickel powder, copper powder and molybdenum powder are matched according to specific weight proportions and mixed evenly. On the one hand, it is beneficial to improve the uniformity of the composition distribution of the high entropy alloy formed during the subsequent ball milling process, and on the other hand, it is beneficial to facilitate the metal powder to achieve atomic level alloying between elements during the subsequent ball milling process.

[0043] In some specific embodiments, the particle size range of the iron powder is 40-50 μm, the particle size range of the cobalt powder is 40-50 μm, the particle size range of the nickel powder is 40-50 μm, the particle size range of the copper powder is 60-70 μm, and the particle size range of the molybdenum powder is 10-20 μm. By controlling the particle size range of each metal powder, the uniformity of the mixed metal powder can be effectively improved, thereby improving the alloying effect during subsequent ball milling and sintering. Specifically, the particle size ranges of iron powder, cobalt powder, and nickel powder are similar, which helps to achieve more uniform mixing and alloying during ball milling; the copper powder has a larger particle size, which can provide better fluidity during the sintering process; the molybdenum powder has a smaller particle size, which helps to be evenly distributed in the mixed metal powder to avoid local aggregation.

[0044] Preferably, the particle size range of iron powder, cobalt powder and nickel powder can be adjusted to 45-50 μm to improve the uniformity of the mixed metal powder; the particle size range of copper powder can be adjusted to 65-70 μm to enhance its fluidity during sintering; the particle size range of molybdenum powder can be adjusted to 10-15 μm to ensure its uniform distribution in the mixed metal powder.

[0045] S2, placing the mixed metal powder into a first ball mill, filling it with argon gas, and ball milling for at least 15 hours to obtain alloyed powder;

[0046] This is the first ball milling, and the whole process is carried out under argon protection to prevent the metal powder from oxidation. At the same time, sufficient alloying of the metal powder is achieved through long-term ball milling.

[0047] In some specific embodiments, the first grinding balls and the mixed metal powder are placed in the first ball mill for ball milling at a ball-to-material ratio of 10 to 20:1; the first grinding balls include first chrome steel balls with a diameter of 5 mm, second chrome steel balls with a diameter of 10 mm, and third chrome steel balls with a diameter of 15 mm, and the quantity ratio of the first chrome steel balls, the second chrome steel balls, and the third chrome steel balls is 3:2:1; the volume of the first ball mill is 1000 to 2000 mL, and the loading amount of the first ball mill is one third of the volume; the first ball mill is placed in a horizontal planetary ball mill and ball milled at a rotation speed of 900 to 1000 rpm and a revolution speed of 200 to 300 rpm.

[0048] The mixed metal powder is fine and loose. By optimizing the ball-to-material ratio, ball type and size ratio, ball mill volume and loading amount, and horizontal planetary ball mill operating parameters during the ball milling process, the ball milling efficiency can be effectively improved, ensuring that the mixed metal powder is fully alloyed and the composition is evenly distributed, thereby improving the quality and performance of the final high-entropy alloy powder.

[0049] Among them, the first grinding ball adopts a combination of chrome steel balls with different diameters, among which the number ratio of balls with diameters of 5mm, 10mm and 15mm is 3:2:1. This combination can achieve the synergistic effect of grinding balls with different particle sizes during the ball milling process, thereby effectively improving the ball milling efficiency, ensuring that the mixed metal powder is fully alloyed during the ball milling process, and is conducive to the uniform distribution of components.

[0050] The volume range of the first ball mill is set to 1000-2000mL, and the loading amount is one third of the volume to ensure that the mixed metal powder can be fully mixed during the ball milling process, while avoiding excessive loading that leads to reduced ball milling efficiency. Preferably, the volume of the first ball mill can be selected to be 1500mL, and the loading amount is 500mL, which can effectively improve the ball milling efficiency and ensure the uniformity and fineness of the alloyed powder.

[0051] The ball milling process of the first ball mill is realized by a horizontal planetary ball mill, wherein the rotation speed is controlled at 900-1000rpm and the revolution speed is controlled at 200-300rpm. This ball milling method can fully mix and alloy the mixed metal powder in the ball mill through the synergistic effect of rotation and revolution, thereby improving the uniformity and fineness of the alloyed powder. Preferably, the rotation speed of the horizontal planetary ball mill can be set to 950rpm and the revolution speed can be set to 250rpm to achieve the best ball milling effect.

[0052] S3, placing the alloyed powder into a mold, and sintering it in a hydrogen atmosphere at 1000-1200° C. to obtain a sintered compact;

[0053] The sintering process is carried out in a high-temperature hydrogen atmosphere, which not only helps to remove oxide impurities, but also helps to promote the bonding of metal powders, further improve the alloying level, and form a dense microstructure, thereby effectively improving its performance stability.

[0054] In some specific embodiments, the sintering time is 30 to 60 minutes; if the sintering time is less than 30 minutes, it is easy to cause insufficient sintering, affecting the formation of a dense microstructure; if the sintering time is longer than 60 minutes, it is easy to cause excessive grain growth, affecting the microstructure and performance of the material; controlling the sintering time within the range of 30 to 60 minutes can effectively balance the sintering effect and material performance.

[0055] Preferably, the sintering is carried out in a hydrogen atmosphere at 1100° C. for 45 minutes to ensure that the oxide impurities are completely removed and the sintered compact has a sufficiently dense microstructure.

[0056] S4, crushing the sintered compact into particles, placing the particles into a second ball mill, and ball milling the particles in an argon atmosphere for at least 20 hours to obtain a high entropy alloy powder;

[0057] The crushing and re-milling steps further refine the alloy powder, which can significantly improve its uniformity and activity, thereby effectively improving the performance stability, wettability and filling properties of the high entropy alloy powder.

[0058] In some specific embodiments, the second grinding balls and the sintered compact crushed into particles are placed in the second ball mill for ball milling at a ball-to-material ratio of 40 to 50:1; the second grinding balls include a first tungsten carbide ball with a diameter of 2 mm, a second tungsten carbide ball with a diameter of 10 mm, and a third tungsten carbide ball with a diameter of 20 mm, and the quantity ratio of the first tungsten carbide ball, the second tungsten carbide ball and the third tungsten carbide ball is 5:3:1; the volume of the second ball mill is 3000 to 4000 mL, and the loading amount of the second ball mill is one third of the volume; the second ball mill is placed in a vibrating ball mill and ball milled at a vibration frequency of 23 to 30 Hz and a vibration amplitude of 3 to 5 mm.

[0059] The sintered blocks broken into particles are hard and have high strength. By optimizing the ball-to-material ratio, ball type and size ratio, ball mill volume and loading amount, and vibration ball mill operating parameters during the ball milling process, the ball milling efficiency can be effectively improved, ensuring the uniform refinement of the sintered blocks broken into particles, thereby improving the quality and performance of the final high-entropy alloy powder.

[0060] Among them, the second grinding ball adopts a combination of tungsten carbide balls with different diameters, among which the number ratio of balls with diameters of 2mm, 10mm and 20mm is 5:3:1. Tungsten carbide balls have high hardness and wear resistance and can maintain stable performance during the ball milling process; at the same time, the combination of tungsten carbide balls with different diameters can achieve the synergistic effect of grinding balls with different particle sizes during the ball milling process, which can not only effectively improve the ball milling efficiency, but also ensure that the particles after the sintered block is crushed are fully refined, which is conducive to the uniform distribution of components and improves its activity.

[0061] The volume range of the second ball mill is set to 3000-4000 mL, and the loading amount is also one-third of the volume to ensure that the particles after the sintered block is crushed can be evenly refined during the ball milling process to obtain high entropy alloy powder. Preferably, the volume of the second ball mill can be selected to be 3500 mL, and the loading amount is 1167 mL, which can effectively improve the ball milling efficiency and ensure the uniformity and fineness of the high entropy alloy powder.

[0062] The ball milling process of the second ball mill is realized by a vibrating ball mill, wherein the vibration frequency is controlled at 23 to 30 Hz and the vibration amplitude is controlled at 3 to 5 mm. This ball milling method further refines the particles after the sintered green block is broken by high-frequency vibration, thereby obtaining a high-entropy alloy powder with smaller particle size and more uniform distribution. Preferably, the vibration frequency of the vibrating ball mill can be set to 25 Hz and the vibration amplitude can be set to 4 mm to ensure that the particle size and uniformity of the high-entropy alloy powder meet the expected standards.

[0063] S5. According to the second weight ratio, weigh 6 to 12 parts of the high entropy alloy powder, 0.3 to 0.6 parts of borax and 0.1 to 0.3 parts of polyvinyl alcohol, mix them evenly, and obtain a high entropy alloy high temperature brazing filler metal;

[0064] The high entropy alloy powder is mixed with borax and polyvinyl alcohol according to specific weight proportions. The high entropy alloy high-temperature solder finally obtained has the advantages of good composition uniformity, high performance stability, excellent wettability and filling properties, and can effectively ensure the welding quality of the brazed joint.

[0065] Among them, borax can react with metal oxides at high temperatures to form fusible borates, thereby effectively removing oxides and providing a clean metal surface for the brazing process; the addition of borax can lower the melting point of high-entropy alloy high-temperature brazing filler metals and improve their fluidity, so that high-entropy alloy high-temperature brazing filler metals can more easily penetrate into the weld, have good filling properties, and easily form a good connection; therefore, by removing oxides and improving fluidity, borax can significantly improve the strength and reliability of the brazed joint, thereby enhancing the durability of the entire connection structure.

[0066] Among them, polyvinyl alcohol can play a role in increasing the viscosity of high-entropy alloy high-temperature solder, making it easy to shape and able to easily cope with various complex welding scenarios; moreover, the addition of polyvinyl alcohol can improve the wettability of the solder to the metal surface, allowing the solder to cover the metal surface more evenly, thereby improving the uniformity and quality of brazing.

[0067] The preparation method of the high-entropy alloy high-temperature brazing material of the present invention comprises the following steps: iron powder, cobalt powder, nickel powder, copper powder and molybdenum powder are matched according to specific weight proportions and mixed evenly, which is beneficial to improving the uniformity of the component distribution of the high-entropy alloy formed during the subsequent ball milling process, and is beneficial to facilitating the metal powder to easily achieve the atomic level alloying between elements during the subsequent ball milling process; the first ball milling process is carried out under the protection of argon gas to prevent the metal powder from being oxidized, and at the same time, the metal powder is fully alloyed through long-term ball milling; the sintering process is carried out in a high-temperature hydrogen atmosphere, which is not only helpful to remove oxide impurities, It also helps to promote the bonding of metal powders, further improve the alloying level, and form a dense microstructure, thereby effectively improving its performance stability; the crushing and re-ball milling steps further refine the alloy powder, which can significantly improve its uniformity and activity, thereby effectively improving the performance stability, wettability and filling properties of the high-entropy alloy powder; finally, the high-entropy alloy powder is mixed with borax and polyvinyl alcohol according to specific weight proportions, and the obtained high-entropy alloy high-temperature brazing filler metal has the advantages of good composition uniformity, high performance stability, excellent wettability and filling properties, and can effectively guarantee the welding quality of the brazed joint.

[0068] Example 2

[0069] The present invention also provides a high-entropy alloy high-temperature brazing filler metal, which is prepared by the preparation method of the high-entropy alloy high-temperature brazing filler metal. The preparation method adopts a specific metal powder ratio, a two-step ball milling process, a high-temperature sintering step, and the addition of auxiliary materials, etc. The high-entropy alloy high-temperature brazing filler metal has the advantages of good composition uniformity, high performance stability, excellent wettability and filling properties, and can effectively ensure the welding quality of the brazed joint.

[0070] Example 3

[0071] Figure 2 A schematic cross-sectional structure diagram of a broken long axis repaired by welding in an embodiment of the present invention is shown.

[0072] The present invention also provides an application of the high entropy alloy high temperature brazing filler metal in welding and repairing a broken long shaft, comprising the following steps:

[0073] Flatten the fracture surface of the first broken shaft segment 10 to form a first plane; form a first chamfer at the edge of the first plane, and form a first connecting hole at the center of the first plane;

[0074] Flatten the fracture surface of the second broken shaft segment 20 to form a second plane; form a second chamfer at the edge of the second plane, and form a second connecting hole at the center of the second plane;

[0075] Insert both ends of the connecting shaft 30 into the first connecting hole and the second connecting hole respectively, and there is a welding gap between the first plane and the second plane, and the welding gap exposes a portion of the connecting shaft 30;

[0076] The high-entropy alloy high-temperature brazing material is evenly placed around the connecting shaft 30 at the opening of the first connecting hole, and brazing is performed by using a flame as a heat source to form a first weld in the welding interval;

[0077] The high-entropy alloy high-temperature brazing material is evenly placed around the connecting shaft 30 at the opening of the second connecting hole, and brazing is performed by using a flame as a heat source to form a second weld in the welding interval;

[0078] Overlay welding is performed from the welding interval until the first chamfer and the second chamfer are covered to form a main weld 40 .

[0079] In the traditional method of repairing a broken long shaft by welding, both ends of the connecting shaft 30 are interference fit in the corresponding connecting holes, which easily causes stress concentration, resulting in wear, deformation or damage of the mating surface, thereby affecting the performance and life of the long shaft.

[0080] The present invention adopts high-entropy alloy high-temperature brazing material to braze the connecting shaft 30, and fixes the two ends of the connecting shaft 30 in the corresponding connecting holes; the high-entropy alloy high-temperature brazing material has good uniformity of composition, high performance stability, excellent wettability and filling properties, and high welding quality, and can ensure a firm connection between the connecting shaft 30 and the connecting hole. At the same time, the weld formed by the brazing connection can evenly distribute stress, avoid stress concentration, and thus reduce the risk of wear, deformation and damage of the mating surface; combined with surfacing, the strength of the repaired long shaft can be guaranteed, and the service life of the repaired long shaft can be effectively extended.

[0081] In some specific embodiments, the first connecting hole and the second connecting hole are coaxial, ensuring that the connecting shaft 30 can remain centered when inserted, thereby avoiding deviation during the welding process.

[0082] Specifically, the depths of the first connecting hole and the second connecting hole are both 50 to 100 mm, and the diameters of the first connecting hole and the second connecting hole are both 20 to 30 mm; the depth and diameter range of the connecting holes are optimized, which not only ensures the firmness of the connection, but also avoids welding difficulties caused by holes that are too large or too small.

[0083] Preferably, the depth of the first connecting hole and the second connecting hole are both 75 mm, and the diameter of the first connecting hole and the second connecting hole are both 25 mm, so that the connecting shaft 30 can form a reliable connection with the connecting hole, and it is also convenient for brazing and fixing.

[0084] In some specific embodiments, the width of the welding interval ranges from 10 to 20 mm, which provides sufficient operating space for brazing on the one hand, and avoids insufficient welding strength of surfacing due to too large an interval on the other hand. Preferably, the width of the welding interval can be 15 mm, which has high welding efficiency.

[0085] In some specific embodiments, the first chamfer and the second chamfer are equal in size, and the sizes of the first chamfer and the second chamfer are both C5-C10, which is conducive to increasing the coverage area of ​​the main weld 40 during surfacing, thereby enhancing the connection strength of the first broken shaft section 10 and the second broken shaft section 20, ensuring the strength of the repaired long shaft, and effectively extending the service life of the repaired long shaft. Preferably, the sizes of the first chamfer and the second chamfer are both C8.

[0086] In some specific embodiments, the gap between the connecting shaft 30 and the hole wall of the first connecting hole is 0.01-0.05 mm, and the gap between the connecting shaft 30 and the hole wall of the second connecting hole is 0.01-0.05 mm, and an extremely stable connection can be formed after brazing.

[0087] The above is a detailed introduction to a high-entropy alloy high-temperature brazing material and its preparation method and application provided in an embodiment of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technical personnel in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for preparing a high-entropy alloy high-temperature brazing material, characterized in that: The following steps are involved: S1. According to the first weight ratio, weigh 1 to 2 parts of iron powder, 1 to 2 parts of cobalt powder, 1 to 2 parts of nickel powder, 5 to 6 parts of copper powder and 0.3 to 0.8 parts of molybdenum powder, mix them evenly to obtain a mixed metal powder; S2, placing the mixed metal powder into a first ball mill, filling it with argon gas, and ball milling for at least 15 hours to obtain alloyed powder; S3, placing the alloyed powder into a mold, and sintering it in a hydrogen atmosphere at 1000-1200° C. to obtain a sintered compact; S4, crushing the sintered compact into particles, placing the particles into a second ball mill, and ball milling the particles in an argon atmosphere for at least 20 hours to obtain a high entropy alloy powder; S5. According to the second weight proportion, weigh 6 to 12 parts of the high entropy alloy powder, 0.3 to 0.6 parts of borax and 0.1 to 0.3 parts of polyvinyl alcohol, mix them evenly, and obtain a high entropy alloy high-temperature brazing material.

2. The method for preparing a high entropy alloy high temperature brazing filler metal according to claim 1, characterized in that: The particle size range of the iron powder is 40-50 μm, the particle size range of the cobalt powder is 40-50 μm, the particle size range of the nickel powder is 40-50 μm, the particle size range of the copper powder is 60-70 μm, and the particle size range of the molybdenum powder is 10-20 μm.

3. The method for preparing a high entropy alloy high temperature brazing filler metal according to claim 1, characterized in that: In step S2, the first grinding balls and the mixed metal powder are placed in the first ball milling tank at a ball-to-material ratio of 10 to 20:1 for ball milling; In step S4, the second grinding balls and the sintered compact crushed into particles are placed in the second ball milling jar at a ball-to-material ratio of 40 to 50:1 for ball milling.

4. The method for preparing a high-entropy alloy high-temperature brazing filler metal according to claim 3, characterized in that: The first grinding ball includes a first chrome steel ball with a diameter of 5 mm, a second chrome steel ball with a diameter of 10 mm, and a third chrome steel ball with a diameter of 15 mm, and the number ratio of the first chrome steel ball, the second chrome steel ball, and the third chrome steel ball is 3:2:1; The second grinding ball includes a first tungsten carbide ball with a diameter of 2 mm, a second tungsten carbide ball with a diameter of 10 mm, and a third tungsten carbide ball with a diameter of 20 mm. The quantity ratio of the first tungsten carbide ball, the second tungsten carbide ball and the third tungsten carbide ball is 5:3:

1.

5. The method for preparing a high entropy alloy high temperature brazing filler metal according to claim 3, characterized in that: The volume of the first ball mill is 1000-2000 mL, and the loading amount of the first ball mill is one third of the volume; The volume of the second ball mill is 3000-4000 mL, and the loading amount of the second ball mill is one third of the volume.

6. The method for preparing a high entropy alloy high temperature brazing filler metal according to claim 3, characterized in that: The first ball mill is placed in a horizontal planetary ball mill, and ball milled at a rotation speed of 900 to 1000 rpm and a revolution speed of 200 to 300 rpm; The second ball milling jar is placed in a vibrating ball mill, and ball milling is performed at a vibration frequency of 23 to 30 Hz and a vibration amplitude of 3 to 5 mm.

7. The method for preparing a high-entropy alloy high-temperature brazing filler metal according to claim 1, wherein: In step S3, the sintering time is 30 to 60 minutes.

8. A high entropy alloy high temperature brazing material, characterized in that: The high entropy alloy high temperature brazing filler metal is prepared by the preparation method of the high entropy alloy high temperature brazing filler metal according to any one of claims 1 to 7.

9. A use of the high entropy alloy high temperature brazing filler metal as claimed in claim 8 in welding and repairing a broken long shaft, characterized in that: The following steps are involved: Flattening the fracture surface of the first broken shaft segment to form a first plane; forming a first chamfer at the edge of the first plane, and forming a first connecting hole at the center of the first plane; Flattening the fracture surface of the second broken shaft segment to form a second plane; forming a second chamfer at the edge of the second plane, and forming a second connecting hole at the center of the second plane; Inserting two ends of the connecting shaft into the first connecting hole and the second connecting hole respectively, with a welding gap between the first plane and the second plane, and the welding gap exposes a portion of the connecting shaft; The high-entropy alloy high-temperature brazing material is evenly placed around the connecting shaft at the opening of the first connecting hole, and brazing is performed by using a flame as a heat source to form a first weld in the welding interval; The high-entropy alloy high-temperature brazing material is evenly placed around the connecting shaft at the opening of the second connecting hole, and brazing is performed by using a flame as a heat source to form a second weld in the welding interval; Overlay welding is performed from the welding interval until the first chamfer and the second chamfer are covered to form a main weld.

10. Use of the high entropy alloy high temperature brazing filler metal as claimed in claim 9 in welding and repairing a broken long shaft, characterized in that: The first connection hole and the second connection hole are coaxial, the depth of the first connection hole and the second connection hole are both 50-100 mm, and the diameter of the first connection hole and the second connection hole are both 20-30 mm; The width of the welding interval ranges from 10 to 20 mm; The sizes of the first chamfer and the second chamfer are equal, and the sizes of the first chamfer and the second chamfer are both C5-C10.

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