A heat treatment method to improve the mechanical properties and wear resistance of CuMnNiSn-based medium-entropy copper alloys

Abstract

This invention provides a heat treatment method for improving the mechanical properties and wear resistance of CuMnNiSn-based medium-entropy copper alloys, relating to the field of high-entropy alloy preparation technology. The heat treatment method provided by this invention includes the following steps: sequentially subjecting a CuMnNiSn-based medium-entropy copper alloy ingot to homogenization annealing, solution treatment, water quenching, and aging treatment; the homogenization annealing temperature is 780–850℃, and the holding time is 180–240 min; the solution treatment temperature is 880–950℃, and the holding time is 40–60 min; the aging treatment temperature is 400–550℃, and the holding time is 240–300 min. This invention can simultaneously improve the strength, hardness, ductility, toughness, and other mechanical properties, as well as the wear resistance of CuMnNiSn-based medium-entropy copper alloys.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy preparation technology, specifically to a heat treatment method for improving the mechanical properties and wear resistance of CuMnNiSn-based medium-entropy copper alloys. Background Technology

[0002] Copper and its alloys, as typical functional-structural integrated materials, are widely used in electrical, electronic, mechanical manufacturing, aerospace, and marine engineering fields. Currently, the research directions of high-performance copper alloy materials mainly include microalloyed copper alloys and complex multi-element copper alloys. The method involves adding elements such as Cr, Zr, Ni, Si, Co, Pb, and Si to pure copper or existing bronze and brass to further enhance the strength and hardness of copper materials, thereby achieving different material functions such as high elasticity, high wear resistance, high corrosion resistance, and easy machining.

[0003] Added alloying elements have limited solid solution in copper-based α solid solutions. Therefore, the strengthening of microalloyed copper alloys and complex multi-component copper alloys is mainly related to the hard intermetallic compounds formed by strong interactions between the added elements and the constituent elements, such as ordered phases like β′, δ, and γ2. With increasing content and variety of alloying elements, the presence of large amounts of ordered phases or intermetallic compounds will deteriorate the material's plasticity and toughness, making it difficult to meet the demands for high-performance copper alloys in key material fields such as aerospace, rail transportation, electronic information, and new energy vehicles.

[0004] Medium-entropy copper alloys are a new type of copper alloy material developed based on the design concept of multi-principal-element high-entropy alloys. The most representative is the CuMnNiSn-based medium-entropy copper alloy. This alloy suppresses the formation of brittle intermetallic compounds by generating high configurational entropy through the mixing of multiple high-concentration metallic elements, resulting in a microstructure composed of a Cu-Mn-Ni disordered solid solution matrix and a small amount of ordered solid solution. Compared with conventional copper alloys, CuMnNiSn-based medium-entropy copper alloys have significant advantages in strength, hardness, and ductility, and are expected to break through the performance bottlenecks of conventional copper alloys, becoming an important development direction for high-performance copper alloys.

[0005] Currently, CuMnNiSn-based medium-entropy copper alloys are mainly prepared through melting and casting techniques. However, the as-cast alloy ingots exhibit severe macro / micro elemental segregation and coarse dendrites, which deteriorate the material's mechanical properties, resulting in low strength and hardness, generally poor ductility, and unsatisfactory wear resistance. Their overall performance still has significant room for improvement. Therefore, it is necessary to further enhance the strength, hardness, and wear resistance of CuMnNiSn-based medium-entropy copper alloys to meet the needs of engineering applications. Summary of the Invention

[0006] The purpose of this invention is to provide a heat treatment method to improve the mechanical properties and wear resistance of CuMnNiSn-based medium-entropy copper alloys. This invention can simultaneously improve the strength, hardness, ductility, toughness, and other mechanical properties and wear resistance of CuMnNiSn-based medium-entropy copper alloys, meeting the needs of engineering applications.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a heat treatment method for improving the mechanical properties and wear resistance of CuMnNiSn-based medium-entropy copper alloys, comprising the following steps:

[0009] The CuMnNiSn system medium entropy copper alloy ingots were subjected to homogenization annealing, solution treatment, water quenching and aging treatment in sequence.

[0010] The homogenization annealing temperature is 780–850°C, and the homogenization annealing holding time is 180–240 min.

[0011] The solution treatment temperature is 880–950°C, and the solution treatment holding time is 40–60 min;

[0012] The aging treatment temperature is 400–550°C, and the aging treatment holding time is 240–300 min.

[0013] Preferably, the chemical composition of the CuMnNiSn-based medium-entropy copper alloy ingot, by mass percentage, includes: Cu 28–55 wt.%, Mn 5–30 wt.%, Ni 25–40 wt.%, and Sn 8–14 wt.%.

[0014] Preferably, the preparation method of the CuMnNiSn-based medium-entropy copper alloy ingot includes: melting metal powder to obtain the CuMnNiSn-based medium-entropy copper alloy ingot; the melting temperature is 1200-1500℃, and the melting time is 10-30 min.

[0015] Preferably, the melting includes vacuum induction melting, electric arc melting, or suspension melting.

[0016] Preferably, the heating rate from room temperature to the homogenization annealing temperature is 10–12 °C / min.

[0017] Preferably, the heating rate from the homogenization annealing temperature to the solution treatment temperature is 5–12 °C / min.

[0018] Preferably, the water quenching treatment is carried out in water at room temperature.

[0019] Preferably, the transfer time of the workpiece from the solution treatment to the water quenching treatment is within 10 seconds.

[0020] Preferably, the heating rate from room temperature to the aging treatment temperature is 10–12 °C / min.

[0021] Preferably, the atmosphere for homogenization annealing, solution treatment, water quenching treatment and aging treatment is independently air, vacuum or inert atmosphere.

[0022] This invention provides a heat treatment method to improve the mechanical properties and wear resistance of CuMnNiSn-based medium-entropy copper alloys. Due to the large liquid-solid range between the components and the low melting point of Sn, CuMnNiSn-based medium-entropy copper alloys prepared by casting not only exhibit coarse dendritic structures but also are highly susceptible to microscopic dendritic segregation and macroscopic anti-segregation of Sn, severely affecting the alloy's mechanical properties and cold-working performance. Furthermore, during the solidification process of CuMnNiSn-based medium-entropy copper alloys, when the temperature drops below 800℃, the solubility of Sn atoms in the matrix decreases, leading to the formation of lamellar precipitates at the grain boundaries and within the grains due to solidification reactions in the saturated solid solution matrix. These precipitates, consisting of alternating Sn-rich and Sn-poor regions forming a discontinuous structure, cause grain boundary brittleness, leading to cracking during subsequent deformation. To address the aforementioned technical problems, this invention sequentially subjects CuMnNiSn-based medium-entropy copper alloy ingots to homogenization annealing, solution treatment, water quenching, and aging treatment. After homogenization annealing and solution treatment, the coarse dendrite morphology is significantly reduced, and the microstructure gradually evolves into a homogeneous structure composed of the matrix and a second phase. The Sn atom concentration in the matrix is ​​significantly higher than in the as-cast state, indicating a significantly enhanced solid solution strengthening effect. More importantly, the formation of harmful lamellar structures at grain boundaries is completely suppressed, and the grain boundary morphology is optimized. This invention, through heat treatment, optimizes the microstructure of CuMnNiSn-based medium-entropy copper alloys, significantly improving their hardness, strength, ductility, toughness, and wear resistance. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the heat treatment process for the CuMnNiSn-based medium-entropy copper alloy in the examples.

[0024] Figure 2 Cu in as-cast state 44 Mn7Ni 36 Sn 13 Secondary electron image of the microstructure of medium-entropy copper alloy using scanning electron microscopy (SEM);

[0025] Figure 3 Cu in heat-treated state 44 Mn7Ni 36 Sn13 Secondary electron image of the microstructure of medium-entropy copper alloy using scanning electron microscopy (SEM);

[0026] Figure 4 Cu in as-cast and heat-treated states 44 Mn7Ni 36 Sn 13 Compression stress-strain curves of medium-entropy copper alloys;

[0027] Figure 5 Cu in as-cast state 40 Mn 15 Ni 32 Sn 13 Secondary electron image of the microstructure of a medium-entropy copper alloy using scanning electron microscopy (SEM);

[0028] Figure 6 Cu in heat-treated state 40 Mn 15 Ni 32 Sn 13 Secondary electron image of the microstructure of medium-entropy copper alloy using scanning electron microscopy (SEM);

[0029] Figure 7 Cu in as-cast and heat-treated states 40 Mn 15 Ni 32 Sn 13 Compression stress-strain curves of medium-entropy copper alloys. Detailed Implementation

[0030] This invention provides a heat treatment method for improving the mechanical properties and wear resistance of CuMnNiSn-based medium-entropy copper alloys, comprising the following steps:

[0031] The CuMnNiSn system medium entropy copper alloy ingots were subjected to homogenization annealing, solution treatment, water quenching and aging treatment in sequence.

[0032] The homogenization annealing temperature is 780–850°C, and the homogenization annealing holding time is 180–240 min.

[0033] The solution treatment temperature is 880–950°C, and the solution treatment holding time is 40–60 min;

[0034] The aging treatment temperature is 400–550°C, and the aging treatment holding time is 240–300 min.

[0035] In this invention, the chemical composition of the CuMnNiSn-based medium-entropy copper alloy ingot, by mass percentage, preferably includes: Cu 28–55 wt.%, Mn 5–30 wt.%, Ni 25–40 wt.%, Sn 8–14 wt.%; more preferably, it includes Cu 40–44 wt.%, Mn 7–15 wt.%, Ni 32–36 wt.%, Sn 13 wt.%.

[0036] In this invention, the preferred method for preparing the CuMnNiSn-based medium-entropy copper alloy ingot includes: melting metal powder to obtain the CuMnNiSn-based medium-entropy copper alloy ingot. In this invention, the purity of the metal powder is preferably ≥99.9 wt.%.

[0037] In this invention, the melting temperature is preferably 1200–1500°C, more preferably 1300–1400°C; the melting time is preferably 10–30 min, more preferably 15–20 min. In this invention, the melting preferably includes vacuum induction melting, electric arc melting, or suspension melting.

[0038] In this invention, the CuMnNiSn-based medium-entropy copper alloy ingot is preferably a cylindrical sample with a preferred size of Φ25mm×10mm.

[0039] In this invention, the CuMnNiSn-based medium-entropy copper alloy ingot preferably undergoes pretreatment before homogenization annealing; the pretreatment preferably includes sequential sanding, ultrasonic cleaning, and drying. In this invention, the sandpaper used for sanding preferably includes one or more of 80# SiC sandpaper, 240# SiC sandpaper, and 600# SiC sandpaper. This invention removes oil and impurities from the ingot surface through sanding. In this invention, the ultrasonic cleaning is preferably performed in acetone. In this invention, the drying temperature is preferably 70°C; the drying time is preferably 20 minutes.

[0040] In this invention, the homogenization annealing temperature is 780–850°C, preferably 820–840°C; the holding time for homogenization annealing is 180–240 min, preferably 200–220 min. In this invention, the heating rate from room temperature to the homogenization annealing temperature is preferably 10–12°C / min, more preferably 10°C / min. In this invention, the atmosphere for homogenization annealing is preferably air, vacuum, or an inert atmosphere. In this invention, the homogenization annealing is preferably carried out in a heating furnace; the heating furnace preferably includes one of a muffle furnace, a resistance furnace, a natural gas furnace, a carbon tube furnace, a vacuum heating furnace, and an atmosphere heating furnace.

[0041] In this invention, a homogenization annealing of appropriate duration is carried out in the temperature range of 780 to 850°C. A higher annealing temperature helps to improve the atomic migration rate and diffusion coefficient, promotes the solid dissolution of easily segregated elements in the matrix phase, and eliminates coarse dendrite morphology.

[0042] In this invention, the solution treatment temperature is 880–950°C, preferably 900°C; the holding time for the solution treatment is 40–60 min, preferably 50–55 min. In this invention, the heating rate from the homogenization annealing temperature to the solution treatment temperature is preferably 5–12°C / min, more preferably 5–10°C / min. In this invention, the atmosphere for the solution treatment is preferably air, vacuum, or an inert atmosphere. In this invention, the solution treatment is preferably carried out in a heating furnace; the heating furnace preferably includes one of a muffle furnace, a resistance furnace, a natural gas furnace, a carbon tube furnace, a vacuum heating furnace, and an atmosphere heating furnace.

[0043] This invention sets the solution treatment temperature at 880–950°C. At this temperature, the Sn-rich phase and lamellar precipitates can fully dissolve into the matrix phase to form a supersaturated solid solution. This not only helps to improve the solid solubility of Sn atoms and ensure the effect of subsequent age-hardening, but also prevents excessive grain growth. This step can be used to enhance the solid solution strengthening effect of atoms with low solid solubility and improve the ductility and toughness of the alloy.

[0044] In this invention, the water quenching treatment is preferably performed in water at room temperature. In this invention, the transfer time of the workpiece from the solution treatment to the water quenching treatment is preferably within 10 seconds, more preferably 7 to 10 seconds. In this invention, the atmosphere for the water quenching treatment is preferably air, vacuum, or an inert atmosphere.

[0045] The present invention employs the above-mentioned water quenching treatment, which can prevent the precipitation of harmful lamellar structures during the slow cooling process of alloy ingots and stabilize the supersaturated solid solution.

[0046] Preferably, after the water quenching treatment, the workpiece cooled to room temperature is dried. In this invention, the drying temperature is preferably 70°C; the drying time is preferably 20 minutes.

[0047] In this invention, the aging treatment temperature is 400–550°C, preferably 450°C; the holding time for the aging treatment is 240–300 min, preferably 260–280 min. In this invention, the heating rate from room temperature to the aging treatment temperature is preferably 10–12°C / min, more preferably 10°C / min.

[0048] In this invention, the atmosphere for the aging treatment is preferably air, vacuum, or an inert atmosphere. In this invention, the aging treatment is preferably carried out in a heating furnace; the heating furnace preferably includes one of a muffle furnace, a resistance furnace, a natural gas furnace, a carbon tube furnace, a vacuum heating furnace, and an atmosphere heating furnace.

[0049] The present invention employs the above-mentioned aging treatment, which can eliminate the thermal stress generated inside the ingot by water quenching and promote the formation of precipitated phases in the microstructure.

[0050] Preferably, after the aging treatment, the resulting alloy is cooled to room temperature in the furnace.

[0051] The heat treatment method of this invention can significantly improve the macroscopic segregation phenomenon of CuMnNiSn system medium entropy copper alloy, eliminate coarse dendrite structure, obtain a stable structure with uniform composition, and significantly improve its mechanical properties such as strength, hardness, plasticity and toughness, as well as wear resistance, so that it has comprehensive properties of high strength, high hardness, high plasticity and toughness and high wear resistance.

[0052] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0053] Example 1

[0054] like Figure 1 As shown, Cu with strong plasticity and wear resistance is obtained through heat treatment. 44 Mn7Ni 36 Sn 13 Medium-entropy copper alloy (chemical composition by mass percentage: Cu 44 wt.%, Mn 7 wt.%, Ni 36 wt.%, Sn 13 wt.%).

[0055] Using Cu, Mn, Ni, and Sn metal powders with a purity of 99.9 wt.% as raw materials, according to Cu 44 Mn7Ni 36 Sn 13 The weight percentage of each component in the medium-entropy copper alloy was weighed out and the metal powder was thoroughly mixed. Then, the powder mixture was heated to a molten state in a vacuum melting furnace, and the temperature was further increased to 1500℃ for 15 minutes for refining. After the melting was completed, the mixture was cooled to room temperature in the furnace to obtain a medium-entropy copper alloy ingot.

[0056] Core samples were taken from medium-entropy copper alloy ingots using wire cutting equipment and machined into cylindrical specimens with a diameter of 25 mm × 10 mm. Surface oil and impurities were removed using 240# SiC sandpaper and 600# SiC sandpaper, followed by ultrasonic cleaning in acetone. The specimens were then dried in an oven at 70°C for 20 minutes to obtain as-cast Cu. 44 Mn7Ni 36 Sn 13 Medium-entropy copper alloy;

[0057] Homogenization annealing: the as-cast Cu 44 Mn7Ni 36 Sn 13 The medium-entropy copper alloy was placed in a resistance furnace and heated from room temperature to 820°C at a heating rate of 10°C / min in air atmosphere, and held at that temperature for 240 min.

[0058] Solution treatment: After homogenization annealing and holding, the sample was heated to 900℃ in air at a heating rate of 5℃ / min and held for 60min.

[0059] Water quenching treatment: After the solution treatment and heat preservation are completed, the sample is quickly taken out and placed in room temperature water for cooling. The sample transfer time is 7 seconds.

[0060] Aging treatment: The sample obtained from water quenching was dried at 70℃ for 20 min, then placed in a muffle furnace and heated to 450℃ in air at a heating rate of 10℃ / min. It was held at this temperature for 300 min and then cooled to room temperature in the furnace to obtain heat-treated Cu. 44 Mn7Ni 36 Sn 13 Medium entropy copper alloy.

[0061] Cast and heat-treated Cu 44 Mn7Ni 36 Sn 13 After wire cutting, grinding, and polishing, the evolution of the microstructure of medium-entropy copper alloy before and after heat treatment was analyzed using SEM. The results are as follows: Figure 2 , Figure 3 As shown.

[0062] The Vickers hardness tester, universal testing machine, and rotary friction and wear tester were used to compare the as-cast and heat-treated Cu. 44 Mn7Ni 36 Sn 13 The mechanical properties of medium-entropy copper alloys, including hardness, yield strength, compressive strength, fracture toughness, and wear rate, are shown in Table 1. Figure 4 Cu in as-cast and heat-treated states 44 Mn7Ni 36 Sn 13The compressive stress-strain curves of medium-entropy copper alloys.

[0063] It is evident that the heat treatment method of the present invention can be used to process Cu 44 Mn7Ni 36 Sn 13 The comprehensive mechanical properties and wear resistance of medium-entropy copper alloys are significantly improved.

[0064] Table 1. Cu in as-cast and heat-treated states 44 Mn7Ni 36 Sn 13 Mechanical properties and wear rate of medium-entropy copper alloys

[0065]

[0066] In Table 1, the testing standard for hardness is GB / T 4340.3-2012, the testing standards for yield strength, compressive strength and compressive strain are GB / T 7314-2017, the testing standard for fracture toughness is ASTM E399-12, and the testing standard for wear rate is ASTM G99-17.

[0067] Example 2

[0068] like Figure 1 As shown, Cu with strong plasticity and wear resistance is obtained through heat treatment. 40 Mn 15 Ni 32 Sn 13 Medium-entropy copper alloy (chemical composition by mass percentage: Cu 40 wt.%, Mn 15 wt.%, Ni 32 wt.%, Sn 13 wt.%).

[0069] Using Cu, Mn, Ni, and Sn metal powders with a purity of 99.9 wt.% as raw materials, according to Cu 40 Mn 15 Ni 32 Sn 13 The weight percentage of each component in the medium-entropy copper alloy was weighed out and the metal powder was thoroughly mixed. Then, the powder mixture was heated to a molten state in a vacuum melting furnace, and the temperature was further increased to 1500℃ for 15 minutes for refining. After the melting was completed, the mixture was cooled to room temperature in the furnace to obtain a medium-entropy copper alloy ingot.

[0070] Core samples were taken from medium-entropy copper alloy ingots using wire cutting equipment and machined into cylindrical specimens with a diameter of 25 mm × 10 mm. Surface oil and impurities were removed using 240# SiC sandpaper and 600# SiC sandpaper, followed by ultrasonic cleaning in acetone. The specimens were then dried in an oven at 70°C for 20 minutes to obtain as-cast Cu. 40 Mn 15 Ni 32Sn 13 Medium-entropy copper alloy;

[0071] Homogenization annealing: the as-cast Cu 40 Mn 15 Ni 32 Sn 13 The medium-entropy copper alloy was placed in a resistance furnace and heated from room temperature to 820°C at a heating rate of 10°C / min in air atmosphere, and held at that temperature for 240 min.

[0072] Solution treatment: After homogenization annealing and holding, the sample was heated to 900℃ in air at a heating rate of 5℃ / min and held for 60min.

[0073] Water quenching treatment: After the solution treatment and heat preservation are completed, the sample is quickly taken out and placed in room temperature water for cooling. The sample transfer time is 7 seconds.

[0074] Aging treatment: The sample obtained from water quenching was removed and dried at 70℃ for 20 min. Then it was placed in a resistance furnace and heated to 450℃ in air at a heating rate of 10℃ / min. After holding at this temperature for 300 min, it was cooled with the furnace to obtain heat-treated Cu. 40 Mn 15 Ni 32 Sn 13 Medium entropy copper alloy.

[0075] Cast and heat-treated Cu 40 Mn 15 Ni 32 Sn 13 After wire cutting, grinding, and polishing, the evolution of the microstructure of medium-entropy copper alloy before and after heat treatment was analyzed using SEM. The results are as follows: Figure 5 , Figure 6 As shown.

[0076] Following the test method of Example 1, a Vickers hardness tester, a universal testing machine, and a rotary friction and wear tester were used to compare the as-cast and heat-treated Cu. 40 Mn 15 Ni 32 Sn 13 The mechanical properties of medium-entropy copper alloys, including hardness, yield strength, compressive strength, fracture toughness, and wear rate, are shown in Table 2. Figure 7 Cu in as-cast and heat-treated states 40 Mn 15 Ni 32 Sn 13 The compressive stress-strain curves of medium-entropy copper alloys. It can be seen that heat treatment causes Cu... 40 Mn 15 Ni 32 Sn13 The comprehensive mechanical properties and wear resistance of medium-entropy copper alloys are significantly improved.

[0077] Table 2. As-cast and heat-treated Cu 40 Mn 15 Ni 32 Sn 13 Mechanical properties and wear rate of medium-entropy copper alloys

[0078]

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A heat treatment method for improving the mechanical properties and wear resistance of CuMnNiSn-based medium-entropy copper alloys, comprising the following steps: The CuMnNiSn system medium entropy copper alloy ingots were subjected to homogenization annealing, solution treatment, water quenching and aging treatment in sequence. The homogenization annealing temperature is 780~850℃, and the homogenization annealing holding time is 180~240min; The solution treatment temperature is 880~950℃, and the solution treatment holding time is 40~60min; The aging treatment temperature is 400~550℃, and the aging treatment holding time is 240~300min; The chemical composition of the CuMnNiSn-based medium-entropy copper alloy ingot, by mass percentage, includes: Cu 28~55 wt.%, Mn 5~30 wt.%, Ni 25~40 wt.%, Sn 13~14 wt.%. The heating rate from room temperature to the homogenization annealing temperature is 10~12℃ / min; The heating rate from the homogenization annealing temperature to the solution treatment temperature is 5~12℃ / min.

2. The heat treatment method according to claim 1, characterized in that, The preparation method of the CuMnNiSn system medium-entropy copper alloy ingot includes: melting metal powder to obtain CuMnNiSn system medium-entropy copper alloy ingot; the melting temperature is 1200~1500℃, and the melting time is 10~30min.

3. The heat treatment method according to claim 2, characterized in that, The smelting process includes vacuum induction smelting, electric arc smelting, or suspension smelting.

4. The heat treatment method according to claim 1, characterized in that, The water quenching treatment is carried out in water at room temperature.

5. The heat treatment method according to claim 1, characterized in that, The transfer time of the workpiece from the solution treatment to the water quenching treatment is within 10 seconds.

6. The heat treatment method according to claim 1, characterized in that, The heating rate from room temperature to the aging treatment temperature is 10~12℃ / min.

7. The heat treatment method according to claim 1, characterized in that, The atmosphere for homogenization annealing, solution treatment, water quenching treatment, and aging treatment is independently air, vacuum, or inert atmosphere.

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