A method for brazing nickel-based superalloy by using FeCoNiCuB high-entropy brazing filler metal

Abstract

The application discloses a method for brazing nickel-based high-temperature alloy by using FeCoNiCuB high-entropy brazing filler metal, and relates to the fields of high-entropy alloy brazing filler metal and welding technology.The application aims to solve the problems of the generation of brittle compounds in a weld, the limited strength of a solid solution of the weld and the insufficient high-temperature stability of a traditional nickel-based high-temperature alloy brazing method.The high-entropy brazing filler metal used in the application has multiple component types and high contents, and the atomic arrangement is relatively disordered, so that the mixed entropy of the atomic arrangement is high, and the generation of intermetallic compounds can be effectively inhibited.Meanwhile, B is used as a melting point reducing element, B can diffuse to both sides of the base metal during the holding process, the melting point of the weld is increased, and the stability of the high-temperature strength of the joint is improved.The application can obtain a method for brazing nickel-based high-temperature alloy by using FeCoNiCuB high-entropy brazing filler metal.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy brazing filler metal and welding technology, specifically to a method for brazing nickel-based superalloys using FeCoNiCuB high-entropy brazing filler metal. Background Technology

[0002] Nickel-based superalloys exhibit structural stability, excellent corrosion and oxidation resistance, and high strength, making them suitable as structural materials at temperatures ranging from 650°C to 1000°C. They are commonly used in the manufacture of hot-end components such as turbine disks and combustion chamber walls for aero-engines. Brazing can produce dense weld joints without deformation, avoiding the melting of the base material. Furthermore, brazing is typically performed under vacuum conditions, preventing oxidation and the introduction of porosity. It also has no specific shape or size requirements for the parts, enabling mass production. Therefore, brazing has become the most common method for manufacturing superalloys with complex shapes and dimensions.

[0003] Currently, nickel-based brazing filler metals are commonly used for brazing nickel-based superalloys. These filler metals contain elements such as Cr, B, and Si. Continuous brittle intermetallic compounds tend to form at the brazing weld joint. With sufficient holding time, B and Si in the weld will diffuse into the base metal, causing the brittle intermetallic compounds in the weld to disappear and present as a pure solid solution phase. However, the strength of the base metal is limited by the strength of the weld solid solution.

[0004] High-entropy alloys, due to their significant high-entropy effect, lattice distortion effect, and slow diffusion effect, readily achieve an ideal balance of strength and ductility. This property makes them particularly suitable for welding, enhancing the mechanical properties of welded joints. Furthermore, high-entropy alloys exhibit a "cocktail" effect, capable of improving phase composition and suppressing the formation of brittle compounds by adjusting the types and contents of alloying elements. Therefore, high-entropy alloys hold immense potential for application in brazing filler metals. However, current FeCoNi-based high-entropy alloy brazing filler metals have relatively high melting points. While methods such as adjusting component composition, adding low-melting-point components, and employing eutectic high-entropy alloys are commonly used to lower the melting point, none of these approaches consider the high-temperature stability of the weld, which is detrimental to the high-temperature service stability of the welded joint. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of easy formation of brittle compounds in the weld, limited strength of the weld solid solution, and insufficient high-temperature stability during traditional brazing of nickel-based superalloys, and to provide a method for brazing nickel-based superalloys with FeCoNiCuB high-entropy brazing filler metal.

[0006] A method for brazing nickel-based superalloys using FeCoNiCuB high-entropy solder comprises the following steps: Step S1: Weighing; Weigh the metal raw materials according to the atomic percentages of Ni, Co, Fe, Cu and B in the high-entropy brazing filler metal as (30~35):(30~35):(5~10):(10~20):(15~20); Step S2: Prepare high-entropy alloy brazing filler metal ingots; The metal raw materials weighed in step S1 are subjected to arc melting under vacuum or argon protective atmosphere to obtain high-entropy alloy brazing ingots. Step S3: Prepare high-entropy alloy brazing foil; The high-entropy alloy brazing ingot obtained in step S2 is crushed into particles by mechanical crushing. After cleaning and drying, the particles are placed in a quartz tube and then placed in the induction heating coil of a high-vacuum single-roller spinning machine. The vacuum is first drawn and then filled with argon gas for protection. Then, the molten brazing material is sprayed onto the copper roller at a temperature of 1200~1300℃ to prepare high-entropy alloy brazing foil. Step S4: Prepare high-entropy alloy solder; The high-entropy alloy solder foil obtained in step S3 is cut and polished to obtain high-entropy solder foil sheet; or the high-entropy alloy solder foil is cut and ball-milled to obtain high-entropy alloy powder, and then a binder is added and mixed evenly to obtain high-entropy alloy solder paste. Step S5: Brazing of nickel-based superalloys; The surfaces of the nickel-based superalloys to be welded are pretreated. Then, the high-entropy brazing foil or high-entropy alloy solder paste obtained in step S4 is placed between the two surfaces of the nickel-based superalloys to be welded. The furnace is then placed in a vacuum brazing furnace and heated to 700-800°C at a heating rate of 10-15°C / min, then to 1000-1100°C at a heating rate of 5-10°C / min, and then to 1120-1200°C at a heating rate of 3-5°C / min. The furnace is then held at 1120-1200°C for 10-120 minutes. After the holding period, the furnace is cooled to 300-400°C and then cooled to room temperature to complete the brazing of the nickel-based superalloys. The two nickel-based superalloys are GH4648 alloy and K416B alloy.

[0007] The principle of this invention: In this invention, Ni, as an important component element in nickel-based superalloys, enables the high-entropy solder to exhibit good wettability and fluidity on the base material surface. Compared with existing FeCoNi-based high-entropy alloy solders with melting points of 1000~1200℃, the FeCoNiCuB high-entropy alloy solder in this invention does not incorporate low-melting-point elements such as Al and Ga, or active elements such as Ti and Mn, thus avoiding the formation of low-melting-point phases in the weld and ensuring the high-temperature stability of the weld. Fe and Co play similar roles, being infinitely miscible with Ni and distributed within the high-entropy alloy matrix, improving the high-temperature stability and toughness of the joint; Cu effectively lowers the melting temperature of the solder and improves the plasticity of the brazed joint; B can form a eutectic reaction with the other four elements, significantly reducing the melting point of the FeCoNiCu system. Simultaneously, the lattice distortion of the high-entropy alloy leads to irregular lattice arrangement, intensifying the resistance to atomic movement and strongly hindering dislocation movement and alloy deformation, thereby producing a significant solid solution strengthening effect. This strengthening effect improves the strength and hardness of the weld.

[0008] The beneficial effects of this invention are: (1) The high-entropy brazing filler metal used in this invention for welding nickel-based superalloys has a variety of components and a high content, and the atomic arrangement is relatively disordered. Therefore, its atomic arrangement has a high mixing entropy, which can effectively suppress the formation of intermetallic compounds. At the same time, the use of B as a melting point reducing element can allow B to diffuse to both sides of the base material during the heat preservation process, thereby increasing the melting point of the weld and improving the stability of the high-temperature strength of the joint.

[0009] (2) The high-entropy brazing filler metal of the present invention has good wettability with the base material. Ni in the brazing filler metal is an important component element in nickel-based superalloys, while Fe, Co and Ni are infinitely miscible and have good compatibility. Therefore, the brazing filler metal can have good wettability with both base materials, and no brittle compounds are generated at the weld joint. The weld is composed of a single solid solution, forming a brazed joint with excellent performance.

[0010] (3) The high-entropy brazing filler metal of the present invention has a suitable melting temperature. The melting point of element Cu is 1083℃, which can reduce the melting point of the brazing filler metal. In addition, Cu, Ni, Co and Fe can undergo eutectic reaction with B, which further reduces the melting point of the brazing filler metal. Therefore, the FeCoNiCuB high-entropy brazing filler metal of the present invention can complete the brazing of nickel-based high-temperature alloys at 1120℃.

[0011] (4) The high-entropy brazing filler metal used in this invention for welding nickel-based high-temperature alloys is foil and solder paste, which can be selected according to the actual situation. It has uniform composition, is easy to assemble, and can better control the brazing gap width. It is an ideal brazing filler metal material and is more suitable for actual production.

[0012] This invention provides a method for brazing nickel-based superalloys using FeCoNiCuB high-entropy solder. Attached Figure Description

[0013] Figure 1 This image shows the microstructure of the high-entropy solder foil prepared in Example 1. Figure 2 This diagram shows the microstructure of the brazed joint of K416B alloy / FeCoNiCuB / GH4648 alloy prepared in Example 1. Figure 3 This diagram shows the elemental distribution of Co in the high-entropy solder foil prepared in Example 1. Figure 4 This diagram shows the elemental distribution of Ni in the high-entropy solder foil prepared in Example 1. Figure 5 This diagram shows the elemental distribution of Fe in the high-entropy solder foil prepared in Example 1. Figure 6 This diagram shows the elemental distribution of Cu in the high-entropy solder foil prepared in Example 1. Detailed Implementation

[0014] A method for brazing nickel-based superalloys using FeCoNiCuB high-entropy solder comprises the following steps: Step S1: Weighing; Weigh the metal raw materials according to the atomic percentages of Ni, Co, Fe, Cu and B in the high-entropy brazing filler metal as (30~35):(30~35):(5~10):(10~20):(15~20); Step S2: Prepare high-entropy alloy brazing filler metal ingots; The metal raw materials weighed in step S1 are subjected to arc melting under vacuum or argon protective atmosphere to obtain high-entropy alloy brazing ingots. Step S3: Prepare high-entropy alloy brazing foil; The high-entropy alloy brazing ingot obtained in step S2 is crushed into particles by mechanical crushing. After cleaning and drying, the particles are placed in a quartz tube and then placed in the induction heating coil of a high-vacuum single-roller spinning machine. The vacuum is first drawn and then filled with argon gas for protection. Then, the molten brazing material is sprayed onto the copper roller at a temperature of 1200~1300℃ to prepare high-entropy alloy brazing foil. Step S4: Prepare high-entropy alloy solder; The high-entropy alloy solder foil obtained in step S3 is cut and polished to obtain high-entropy solder foil sheet; or the high-entropy alloy solder foil is cut and ball-milled to obtain high-entropy alloy powder, and then a binder is added and mixed evenly to obtain high-entropy alloy solder paste. Step S5: Brazing of nickel-based superalloys; The surfaces of the nickel-based superalloys to be welded are pretreated. Then, the high-entropy brazing foil or high-entropy alloy solder paste obtained in step S4 is placed between the two surfaces of the nickel-based superalloys to be welded. The furnace is then placed in a vacuum brazing furnace and heated to 700-800°C at a heating rate of 10-15°C / min, then to 1000-1100°C at a heating rate of 5-10°C / min, and then to 1120-1200°C at a heating rate of 3-5°C / min. The furnace is then held at 1120-1200°C for 10-120 minutes. After the holding period, the furnace is cooled to 300-400°C and then cooled to room temperature to complete the brazing of the nickel-based superalloys. The two nickel-based superalloys are GH4648 alloy and K416B alloy.

[0015] The metal raw material mentioned in step S1 is a metal ingot or an intermediate alloy ingot, and the purity of the metal ingot is 99.9%~100%.

[0016] The vacuum level in step S2 is 5~10 Pa.

[0017] In step S2, the electric arc melting is performed 4 to 5 times in an electric arc melting furnace or an induction melting furnace.

[0018] The vacuum degree in step S3 is 3×10 -3 ~5×10 -3 The pressure of argon gas is 0.05~0.1MPa, and the rotation speed of the copper roller is 20~30m / s.

[0019] The thickness of the high-entropy alloy solder foil mentioned in step S4 is 40~100μm.

[0020] The adhesive mentioned in step S4 is Nicrobraz Cements 320 or Nicrobraz Cements 520.

[0021] In step S4, the ball milling speed is 300~600 rpm, the ball milling time is 6~15 h, and the ball-to-material ratio is (5~15):1.

[0022] In step S5, the surface of the nickel-based superalloy to be welded is pretreated by first grinding and then ultrasonically cleaning it in acetone for 5-10 minutes.

[0023] After the heat preservation in step S5 is completed, the temperature is reduced to 300-400℃ at a cooling rate of 5-10℃ / min.

[0024] The beneficial effects of the present invention are verified using the following embodiments: Example 1: A method for brazing nickel-based superalloys with FeCoNiCuB high-entropy solder, comprising the following steps: Step S1: Weighing; Based on the atomic percentage of the high-entropy solder converted to mass ratio, 0.75g of Fe elemental particles, 3.5g of Co elemental particles, 2.05g of Ni elemental particles, 1.71g of Cu elemental particles, and 1.86g of Ni-B particles (B mass fraction of 22%) were weighed out. The purity of the Fe elemental particles was 99.9%; the Co, Ni, Cu, and Ni-B particles were pure metals or alloys. Step S2: Prepare high-entropy alloy brazing filler metal ingots; The metal raw materials weighed in step S1 are placed in an electric arc melting furnace and electric arc melting is carried out under an argon protective atmosphere to obtain a high-purity high-entropy alloy brazing ingot. Step S3: Prepare high-entropy alloy brazing foil; The high-entropy alloy brazing ingot obtained in step S2 was crushed into particles using mechanical crushing. After cleaning with alcohol and drying, approximately 3g of the particles were placed into a quartz tube, which was then placed inside the induction heating coil of a high-vacuum single-roller belt spinning machine. The vacuum was first evacuated to 5×10⁻⁶. -3 Pa, then argon gas is introduced for protection at a pressure of 0.05 MPa; then, at a temperature of 1200℃, molten brazing filler metal is sprayed onto a copper roller rotating at a speed of 25 m / s to prepare a high-entropy alloy brazing filler metal foil with a thickness of 50 μm; Step S4: Prepare high-entropy alloy solder; The high-entropy alloy solder foil obtained in step S3 is cut into a suitable shape, and the surface is polished by mechanical means to remove the oxide layer on the surface, thus obtaining a high-entropy solder foil sheet. Figure 1 This image shows the microstructure of the high-entropy solder foil prepared in Example 1; as shown. Figure 1 As shown, in this embodiment, the microstructure of the high-entropy brazing foil after single-roller spin quenching is a single solid solution structure with uniform element distribution.

[0025] Figure 3 This diagram shows the elemental distribution of Co in the high-entropy solder foil prepared in Example 1. Figure 4 This diagram shows the elemental distribution of Ni in the high-entropy solder foil prepared in Example 1. Figure 5 This diagram shows the elemental distribution of Fe in the high-entropy solder foil prepared in Example 1. Figure 6 This diagram shows the elemental distribution of Cu in the high-entropy solder foil prepared in Example 1; as shown. Figure 3-6 As shown, in this embodiment, the four elements Co, Ni, Fe and Cu are uniformly distributed in the high-entropy solder foil.

[0026] Step S5: Brazing of nickel-based superalloys; The surfaces of GH4648 alloy and K416B alloy to be welded were first polished with fine sandpaper, and then ultrasonically cleaned in acetone for 10 minutes to remove surface oil and oxides. The high-entropy brazing foil obtained in step S4 was then placed between the surfaces of GH4648 alloy and K416B alloy to be welded, and assembled in the form of K416B alloy / high-entropy brazing foil / GH4648 alloy from top to bottom. After assembly, the surfaces were placed in a vacuum brazing furnace and heated to 800°C at a heating rate of 15°C / min, then to 1100°C at a heating rate of 10°C / min, and then to 1180°C at a heating rate of 5°C / min. The surfaces were held at 1180°C for 15 minutes. After the holding period, the surfaces were cooled to 400°C at a cooling rate of 10°C / min, and then cooled to room temperature with the furnace to complete the brazing of GH4648 alloy and K416B alloy.

[0027] Figure 2 This diagram shows the microstructure of the brazed joint of K416B alloy / FeCoNiCuB / GH4648 alloy prepared in Example 1; as shown. Figure 2 As shown, the high-entropy brazing foil in this embodiment enables the joint to achieve good metallurgical bonding, and the weld structure exhibits a single solid solution state without obvious brittle compound layer. The joint has excellent performance, with a shear strength of 600 MPa, reaching 87% of the strength of the base material GH4648 (688 MPa).

[0028] Example 2: A method for brazing nickel-based superalloys with FeCoNiCuB high-entropy solder, comprising the following steps: Step S1: Weighing; Based on the atomic percentage of the high-entropy solder converted to mass ratio, 0.75g of Fe elemental particles, 3.5g of Co elemental particles, 2.05g of Ni elemental particles, 1.71g of Cu elemental particles, and 1.86g of Ni-B particles (B mass fraction of 22%) were weighed out. The purity of the Fe elemental particles was 99.9%; the Co, Ni, Cu, and Ni-B particles were pure metals or alloys. Step S2: Prepare high-entropy alloy brazing filler metal ingots; The metal raw materials weighed in step S1 are placed in an electric arc melting furnace and electric arc melting is carried out under an argon protective atmosphere to obtain a high-purity high-entropy alloy brazing ingot. Step S3: Prepare high-entropy alloy brazing foil; The high-entropy alloy brazing ingot obtained in step S2 was crushed into particles using mechanical crushing. After cleaning with alcohol and drying, approximately 3g of the particles were placed into a quartz tube, which was then placed inside the induction heating coil of a high-vacuum single-roller belt spinning machine. The vacuum was first evacuated to 5×10⁻⁶. -3Pa, then argon gas is introduced for protection at a pressure of 0.05 MPa; then, at a temperature of 1200℃, molten brazing filler metal is sprayed onto a copper roller rotating at a speed of 25 m / s to prepare a high-entropy alloy brazing filler metal foil with a thickness of 50 μm; Step S4: Prepare high-entropy alloy solder; The high-entropy alloy solder foil obtained in step S3 is cut into small pieces and then ball-milled at a speed of 400 rpm for 6 hours with a ball-to-material ratio of 10:1 to obtain high-entropy alloy powder. Then, an appropriate amount of binder Nicorobraz Cements 520 is added to obtain high-entropy alloy solder paste. Step S5: Brazing of nickel-based superalloys; The surfaces of GH4648 alloy and K416B alloy to be soldered were first polished with fine sandpaper, then ultrasonically cleaned in acetone for 10 minutes to remove surface oil and oxides. The high-entropy alloy solder paste obtained in step S4 was then placed between the surfaces of GH4648 alloy and K416B alloy to be soldered, and assembled in the form of K416B alloy / high-entropy alloy solder paste / GH4648 alloy from top to bottom. After assembly, the surfaces were placed in a vacuum brazing furnace and heated to 800°C at a heating rate of 15°C / min, then to 1100°C at a heating rate of 10°C / min, and then to 1180°C at a heating rate of 5°C / min. The surfaces were held at 1180°C for 15 minutes. After the holding period, the surfaces were cooled to 400°C at a cooling rate of 10°C / min, and then cooled to room temperature with the furnace to complete the brazing of GH4648 alloy and K416B alloy.

Claims

1. A method for brazing nickel-based superalloys with FeCoNiCuB high-entropy solder, characterized in that... This method is performed in the following steps: Step S1: Weighing; Weigh the metal raw materials according to the atomic percentages of Ni, Co, Fe, Cu and B in the high-entropy brazing filler metal as (30~35):(30~35):(5~10):(10~20):(15~20); The metal raw material is a metal ingot or an intermediate alloy ingot, and the purity of the metal ingot is 99.9%~100%. Step S2: Prepare high-entropy alloy brazing filler metal ingots; The metal raw materials weighed in step S1 are subjected to arc melting under vacuum or argon protective atmosphere to obtain high-entropy alloy brazing ingots. The vacuum level is 5~10 Pa; The electric arc melting process is carried out 4 to 5 times in an electric arc melting furnace or an induction melting furnace. Step S3: Prepare high-entropy alloy brazing foil; The high-entropy alloy brazing ingot obtained in step S2 is crushed into particles by mechanical crushing. After cleaning and drying, the particles are placed in a quartz tube and then placed in the induction heating coil of a high-vacuum single-roller spinning machine. The vacuum is first drawn and then filled with argon gas for protection. Then, the molten brazing material is sprayed onto the copper roller at a temperature of 1200~1300℃ to prepare high-entropy alloy brazing foil. Vacuum degree is 3×10 -3 ~5×10 -3 Pa, the pressure of argon gas is 0.05~0.1MPa, and the rotation speed of the copper roller is 20~30m / s; Step S4: Prepare high-entropy alloy solder; The high-entropy alloy solder foil obtained in step S3 is cut and polished to obtain high-entropy solder foil sheet; or the high-entropy alloy solder foil is cut and ball-milled to obtain high-entropy alloy powder, and then a binder is added and mixed evenly to obtain high-entropy alloy solder paste. The thickness of the high-entropy alloy solder foil is 40~100μm; The adhesive is Nicrobraz Cements 320 or Nicrobraz Cements 520; The ball mill speed is 300~600 rpm, the ball milling time is 6~15 h, and the ball-to-material ratio is (5~15):1; Step S5: Brazing of nickel-based superalloys; The surfaces of the nickel-based superalloys to be welded are pretreated. Then, the high-entropy brazing foil or high-entropy alloy solder paste obtained in step S4 is placed between the two surfaces of the nickel-based superalloys to be welded. The furnace is then placed in a vacuum brazing furnace and heated to 700-800°C at a heating rate of 10-15°C / min, then to 1000-1100°C at a heating rate of 5-10°C / min, and then to 1120-1200°C at a heating rate of 3-5°C / min. The furnace is then held at 1120-1200°C for 10-120 minutes. After the holding period, the furnace is cooled to 300-400°C and then cooled to room temperature to complete the brazing of the nickel-based superalloys. The two nickel-based superalloys are GH4648 alloy and K416B alloy. The pretreatment of the surface of the nickel-based superalloy to be welded is to first grind it, and then place it in acetone for ultrasonic cleaning for 5 to 10 minutes. After the heat preservation is completed, the temperature is reduced to 300-400℃ at a cooling rate of 5-10℃ / min.

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