A method for preparing a gradient composition of a manganese-copper alloy with improved toughness

Abstract

A method for preparing a gradient composition of a manganese-copper alloy with improved toughness belongs to the technical field of alloy preparation, and comprises the following steps: uniformly mixing copper powder and manganese powder into surface powder and core powder, and dynamically adjusting the feeding ratio of the surface powder and the core powder by a double powder feeder; performing laser sintering during the feeding process, and adjusting the manganese content in the feed by the double powder feeder for each deposited layer; after the sintering is completed, applying a strong axial magnetic field to drive Mn atoms to migrate toward the tail of the molten pool to form a composition gradient strengthening; performing sequential annealing treatment and surface nano-processing to obtain a manganese-copper alloy; forming nanocrystals and solid solution strengthening by rapid laser cooling to improve the strength of the manganese-copper alloy, and the coarse columnar crystals induced by the magnetic field provide high fracture toughness.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy preparation, and in particular relates to a method for preparing a manganese-copper alloy with improved toughness through a gradient composition. Background Art

[0002] Manganese copper is a precision resistance alloy, typically supplied as wire, with smaller quantities of sheet and strip available. It has a wide range of applications in various instruments and meters. It is also an ultra-high pressure sensitive material, with a maximum pressure measurement limit of up to 500 Pa. Manganese copper's excellent piezoresistive effect is widely used for pressure measurement in high-temperature and high-pressure environments, such as detonation, high-speed impact, dynamic fracture, and new material synthesis.

[0003] Nowadays, structural components in the fields of aerospace, automobile manufacturing, etc. require materials with high-strength toughness and strength. The manganese-copper alloys in the existing technology are difficult to meet the requirements. Therefore, there is an urgent need to provide a manganese-copper alloy that can provide both high strength and high toughness. Summary of the Invention

[0004] In order to overcome some of the problems mentioned in the above background, the present invention provides a method for preparing a gradient composition of a manganese-copper alloy with improved toughness.

[0005] According to the technical solution of the present invention, a method for preparing a gradient composition of a manganese-copper alloy with improved toughness is provided, comprising the following steps:

[0006] The copper powder and the manganese powder are uniformly mixed into surface powder and core powder, and the feeding ratio of the surface powder and the core powder is dynamically adjusted by a double powder feeder;

[0007] During the feeding process, the manganese content in the feed is adjusted by laser sintering with each layer deposited through a double powder feeder;

[0008] After sintering is completed, a strong axial magnetic field is applied to drive the Mn atoms to migrate to the tail of the molten pool to form a composition gradient strengthening;

[0009] The manganese-copper alloy is obtained by sequentially performing annealing treatment and surface nano-crystallization treatment.

[0010] Furthermore, during the laser sintering process, the laser wavelength is 1070 nm, the laser spot diameter is 45-55 μm, the laser scanning power is 300-500 W, and the laser scanning speed is 800-1200 mm / s;

[0011] Laser sintering is performed layer by layer from the core layer to the surface layer, and the inter-layer rotation scanning direction is 67°.

[0012] Furthermore, the magnetic field strength is 11-13 T, and the magnetic field direction is parallel to the deposition direction during the sintering process.

[0013] Furthermore, while applying the magnetic field, the sintered alloy is cooled at a rate of 0.5-2° C. / s.

[0014] Furthermore, the surface layer powder comprises: copper powder and 24-26 wt% manganese powder;

[0015] The core powder includes copper powder and 4-6 wt % manganese powder.

[0016] Furthermore, during the laser sintering process, the thickness of the deposited layer of a single deposition is 25-35 μm, and the manganese content between the deposited layers increases from the core layer to the surface layer, with the manganese content of each layer increasing by 3-6 wt%.

[0017] Furthermore, the annealing treatment is specifically to place the alloy after the strong magnetic treatment in an annealing furnace and anneal it at a temperature of 600° C. for 2 hours under argon protection conditions.

[0018] Furthermore, the surface of the annealed alloy is nano-treated by supersonic projectile technology, wherein the supersonic projectile is a projectile of 0.1-0.5 mm, the pressure of the compressed gas is 4-8 bar, and a single treatment takes 5-30 minutes.

[0019] Furthermore, the present invention also provides a manganese-copper alloy with improved toughness: a manganese-copper alloy prepared by the above method.

[0020] Furthermore, the present invention also provides an application of the manganese-copper alloy with improved toughness, and the manganese-copper alloy with improved toughness is applied in the fields of aerospace, automobile manufacturing, etc.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention uses rapid laser cooling to form nanocrystals + solid solution strengthening to improve the strength of manganese-copper alloy. The coarse columnar crystals induced by the magnetic field provide high fracture toughness. Combined with the continuous change of transition zone composition and grain size, stress concentration is avoided, and crack propagation requires higher energy consumption. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments; based on the embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection.

[0024] An embodiment of the present invention provides a method for preparing a gradient composition of a manganese-copper alloy with improved toughness, comprising the following steps:

[0025] The copper powder and the manganese powder are uniformly mixed into surface powder and core powder, and the feeding ratio of the surface powder and the core powder is dynamically adjusted by a double powder feeder;

[0026] During the feeding process, the manganese content in the feed is adjusted by laser sintering with each layer deposited through a double powder feeder;

[0027] After sintering is completed, a strong axial magnetic field is applied to drive the Mn atoms to migrate to the tail of the molten pool to form a composition gradient strengthening;

[0028] The manganese-copper alloy is obtained by sequentially performing annealing treatment and surface nano-crystallization treatment.

[0029] In a further embodiment of this embodiment, the laser wavelength during the laser sintering process is 1070 nm, the laser spot diameter is 45-55 μm, the laser scanning power is 300-500 W, and the laser scanning speed is 800-1200 mm / s;

[0030] Laser sintering is performed layer by layer from the core layer to the surface layer, and the inter-layer rotation scanning direction is 67°.

[0031] In a further implementation of this embodiment, the magnetic field strength is ≥12 T, and the magnetic field direction is parallel to the deposition direction during the sintering process.

[0032] In a further embodiment of this example, the sintered alloy is cooled at a rate of 0.5-2° C. / s while applying the magnetic field.

[0033] In a further embodiment of this example, the surface layer powder comprises: copper powder and 24-26 wt % manganese powder;

[0034] The core powder includes copper powder and 4-6 wt % manganese powder.

[0035] In a further implementation of this embodiment, during the laser sintering process, the thickness of the deposited layer of a single deposition is 25-35 μm, and the manganese content between the deposited layers increases from the core layer to the surface layer, with the manganese content of each layer increasing by 3-6 wt%.

[0036] In a further implementation manner of this embodiment, the annealing treatment is specifically to place the alloy after the strong magnetic treatment in an annealing furnace and anneal it at a temperature of 600° C. for 2 hours under argon protection conditions.

[0037] In a further implementation of this embodiment, the surface nano-treatment of the annealed alloy is performed by supersonic projectile technology, wherein the supersonic projectile is a projectile of 0.1-0.5 mm, the pressure of the compressed gas is 4-8 bar, and a single treatment time is 5-30 minutes.

[0038] A further embodiment of the present invention also provides a manganese-copper alloy with improved toughness: a manganese-copper alloy prepared by the above method.

[0039] Furthermore, an embodiment of the present invention also provides an application of the manganese-copper alloy with improved toughness, and the manganese-copper alloy with improved toughness is applied in the fields of aerospace, automobile manufacturing, etc.

[0040] It should be noted that selective laser melting dynamically adjusts the manganese / copper powder ratio to create a continuous gradient from high-manganese alloys (high strength) to low-manganese alloys (high toughness). A strong magnetic field exploits the difference in magnetic susceptibility between the paramagnetic properties of Mn and the diamagnetic properties of Cu to suppress dendritic segregation and induce directional columnar growth, further optimizing interfacial bonding. Laser rapid melting refines grains, while the magnetic field suppresses brittle phase precipitation. The combination of these two creates a nanocrystalline-to-columnar gradient transition structure.

[0041] The copper powder and manganese powder are respectively high-purity Cu powder with a purity of more than 99.99% and a particle size of 15-45 μm and high-purity Mn powder with a purity of more than 99.99% and a particle size of 10-30 μm. During the mixing process, the copper powder and manganese powder are mixed by ball milling under argon protection.

[0042] Premixing of two powders before laser sintering:

[0043] The surface powder includes copper powder and 24-26 wt% manganese powder and the core powder includes copper powder and 4-6 wt% manganese powder.

[0044] The laser parameters used in laser sintering are a wavelength of 1070nm, a spot diameter of 45-55μm, and a power of 300-500W. The scanning strategy is to scan with variable parameters in different regions: in the high manganese area, high power of 500W and low speed of 800mm / s are used to ensure full fusion; in the low manganese area, low power of 300W and high speed of 1200mm / s are used instead.

[0045] In the gradient construction, each layer was deposited with a thickness of 25-35 μm along the deposition direction. The Mn content was adjusted by a powder feeder, and the scanning direction was rotated 67° between layers to reduce anisotropy.

[0046] Then, directional solidification is assisted by a magnetic field: after the laser sintering is completed, a strong axial magnetic field ≥12T is immediately applied, the temperature is kept above the liquidus line of the alloy, the direction of the magnetic field is parallel to the deposition direction, and the difference in magnetization force is used to drive the Mn atoms to migrate to the tail of the molten pool, forming a composition gradient strengthening, and slowly cooling at a rate of 0.5-2℃ / s. The magnetic field suppresses Mn segregation and induces the growth of <100> oriented columnar crystals.

[0047] Final structure: The surface is a nanocrystalline Mn-rich area with grains ≤100nm, and the core is a coarse columnar Mn-depleted area with grains ≤10μm.

[0048] Annealing treatment eliminates residual stress, promotes gradient interface diffusion, and surface nano-processing further increases surface compressive stress.

[0049] Example 1

[0050] High-purity Cu powder with a purity of 99.99% or more and a particle size of 15-45 μm and high-purity Mn powder with a purity of 99.99% or more and a particle size of 10-30 μm are mixed by ball milling under argon protection to form a surface powder of copper powder and 24 wt% of manganese powder and a core powder of copper powder and 6 wt% of manganese powder. The feed ratio of the surface powder and the core powder is dynamically adjusted by a double powder feeder.

[0051] Laser sintering is performed during the feeding process, and the manganese content in the feed is adjusted by a double powder feeder after each layer is deposited. The laser parameters use a wavelength of 1070nm, a spot diameter of 50μm, and a power of 300-500W. The scanning strategy is to scan with variable parameters in different regions: in the high-manganese area, high power of 500W and low speed of 800mm / s are used to ensure sufficient fusion; on the contrary, low power of 300W and high speed of 1200mm / s are used in the low-manganese area.

[0052] In the gradient construction, each layer was deposited with a thickness of 30 μm along the deposition direction. The Mn content was adjusted by a powder feeder, and the scanning direction was rotated 67° between layers to reduce anisotropy. The Mn content between the deposited layers increased from the core layer to the surface layer, with the Mn content increasing by 6wt% in each layer.

[0053] After sintering is completed, a strong axial magnetic field is applied to drive the Mn atoms to migrate to the tail of the molten pool to form composition gradient strengthening. Among them, the magnetic field strength is ≥12T, the temperature is kept above the liquidus line of the alloy, and the direction of the magnetic field is parallel to the deposition direction. The difference in magnetizing force is used to drive the Mn atoms to migrate to the tail of the molten pool to form composition gradient strengthening. The alloy is slowly cooled at a rate of 0.5-2℃ / s. The magnetic field suppresses Mn segregation and induces the growth of <100> oriented columnar crystals.

[0054] Final structure: The surface is a nanocrystalline Mn-rich area with grains ≤100nm, and the core is a coarse columnar Mn-depleted area with grains ≤10μm;

[0055] The manganese-copper alloy is obtained by sequentially performing annealing treatment and surface nano-crystallization treatment. During the annealing treatment, the alloy after the strong magnetic treatment is placed in an annealing furnace and annealed for 2 hours at a temperature of 600° C. under argon protection conditions.

[0056] The surface nano-crystallization treatment is performed on the annealed alloy by using supersonic projectile technology, wherein the supersonic projectile is a 0.3 mm projectile, the pressure of the compressed gas is 6 bar, and a single treatment takes 20 minutes.

[0057] Example 2

[0058] High-purity Cu powder with a purity of 99.99% or more and a particle size of 15-45 μm and high-purity Mn powder with a purity of 99.99% or more and a particle size of 10-30 μm are mixed by ball milling under argon protection to form a surface powder of copper powder and 25 wt% of manganese powder and a core powder of copper powder and 5 wt% of manganese powder. The feed ratio of the surface powder and the core powder is dynamically adjusted by a double powder feeder.

[0059] Laser sintering is performed during the feeding process, and the manganese content in the feed is adjusted by a double powder feeder after each layer is deposited. The laser parameters use a wavelength of 1070nm, a spot diameter of 50μm, and a power of 300-500W. The scanning strategy is to scan with variable parameters in different regions: in the high-manganese area, high power of 500W and low speed of 800mm / s are used to ensure sufficient fusion; on the contrary, low power of 300W and high speed of 1200mm / s are used in the low-manganese area.

[0060] In the gradient construction, each layer was deposited with a thickness of 30 μm along the deposition direction. The Mn content was adjusted by a powder feeder, and the scanning direction was rotated 67° between layers to reduce anisotropy. The Mn content between the deposited layers increased from the core layer to the surface layer, with the Mn content increasing by 5wt% in each layer.

[0061] After sintering is completed, a strong axial magnetic field is applied to drive the Mn atoms to migrate to the tail of the molten pool to form composition gradient strengthening. Among them, the magnetic field strength is ≥12T, the temperature is kept above the liquidus line of the alloy, and the direction of the magnetic field is parallel to the deposition direction. The difference in magnetizing force is used to drive the Mn atoms to migrate to the tail of the molten pool to form composition gradient strengthening. The alloy is slowly cooled at a rate of 0.5-2℃ / s. The magnetic field suppresses Mn segregation and induces the growth of <100> oriented columnar crystals.

[0062] Final structure: The surface is a nanocrystalline Mn-rich area with grains ≤100nm, and the core is a coarse columnar Mn-depleted area with grains ≤10μm;

[0063] The manganese-copper alloy is obtained by sequentially performing annealing treatment and surface nano-crystallization treatment. During the annealing treatment, the alloy after the strong magnetic treatment is placed in an annealing furnace and annealed for 2 hours at a temperature of 600° C. under argon protection conditions.

[0064] The surface nano-crystallization treatment is performed on the annealed alloy by using supersonic projectile technology, wherein the supersonic projectile is a 0.3 mm projectile, the pressure of the compressed gas is 6 bar, and a single treatment takes 20 minutes.

[0065] Example 3

[0066] High-purity Cu powder with a purity of 99.99% or more and a particle size of 15-45 μm and high-purity Mn powder with a purity of 99.99% or more and a particle size of 10-30 μm are mixed by ball milling under argon protection to form a surface powder of copper powder and 25 wt% of manganese powder and a core powder of copper powder and 5 wt% of manganese powder. The feed ratio of the surface powder and the core powder is dynamically adjusted by a double powder feeder.

[0067] Laser sintering is performed during the feeding process, and the manganese content in the feed is adjusted by a double powder feeder after each layer is deposited. The laser parameters use a wavelength of 1070nm, a spot diameter of 50μm, and a power of 300-500W. The scanning strategy is to scan with variable parameters in different regions: in the high-manganese area, high power of 500W and low speed of 800mm / s are used to ensure sufficient fusion; on the contrary, low power of 300W and high speed of 1200mm / s are used in the low-manganese area.

[0068] In the gradient construction, each layer was deposited with a thickness of 30 μm along the deposition direction. The Mn content was adjusted by a powder feeder, and the scanning direction was rotated 67° between layers to reduce anisotropy. The Mn content between the deposited layers increased from the core layer to the surface layer, with the Mn content increasing by 4wt% per layer.

[0069] After sintering is completed, a strong axial magnetic field is applied to drive the Mn atoms to migrate to the tail of the molten pool to form composition gradient strengthening. Among them, the magnetic field strength is ≥12T, the temperature is kept above the liquidus line of the alloy, and the direction of the magnetic field is parallel to the deposition direction. The difference in magnetizing force is used to drive the Mn atoms to migrate to the tail of the molten pool to form composition gradient strengthening. The alloy is slowly cooled at a rate of 0.5-2℃ / s. The magnetic field suppresses Mn segregation and induces the growth of <100> oriented columnar crystals.

[0070] Final structure: The surface is a nanocrystalline Mn-rich area with grains ≤100nm, and the core is a coarse columnar Mn-depleted area with grains ≤10μm;

[0071] The manganese-copper alloy is obtained by sequentially performing annealing treatment and surface nano-crystallization treatment. During the annealing treatment, the alloy after the strong magnetic treatment is placed in an annealing furnace and annealed for 2 hours at a temperature of 600° C. under argon protection conditions.

[0072] The surface nano-crystallization treatment is performed on the annealed alloy by using supersonic projectile technology, wherein the supersonic projectile is a 0.3 mm projectile, the pressure of the compressed gas is 6 bar, and a single treatment takes 20 minutes.

[0073] Example 4

[0074] High-purity Cu powder with a purity of 99.99% or more and a particle size of 15-45 μm and high-purity Mn powder with a purity of 99.99% or more and a particle size of 10-30 μm are mixed by ball milling under argon protection to form a surface powder of copper powder and 26 wt% of manganese powder and a core powder of copper powder and 5 wt% of manganese powder. The feed ratio of the surface powder and the core powder is dynamically adjusted by a double powder feeder.

[0075] Laser sintering is performed during the feeding process, and the manganese content in the feed is adjusted by a double powder feeder after each layer is deposited. The laser parameters use a wavelength of 1070nm, a spot diameter of 50μm, and a power of 300-500W. The scanning strategy is to scan with variable parameters in different regions: in the high-manganese area, high power of 500W and low speed of 800mm / s are used to ensure sufficient fusion; on the contrary, low power of 300W and high speed of 1200mm / s are used in the low-manganese area.

[0076] In the gradient construction, each layer was deposited with a thickness of 30 μm along the deposition direction. The Mn content was adjusted by a powder feeder, and the scanning direction was rotated 67° between layers to reduce anisotropy. The Mn content between the deposited layers increased from the core layer to the surface layer, with the Mn content increasing by 3wt% in each layer.

[0077] After sintering is completed, a strong axial magnetic field is applied to drive the Mn atoms to migrate to the tail of the molten pool to form composition gradient strengthening. Among them, the magnetic field strength is ≥12T, the temperature is kept above the liquidus line of the alloy, and the direction of the magnetic field is parallel to the deposition direction. The difference in magnetizing force is used to drive the Mn atoms to migrate to the tail of the molten pool to form composition gradient strengthening. The alloy is slowly cooled at a rate of 0.5-2℃ / s. The magnetic field suppresses Mn segregation and induces the growth of <100> oriented columnar crystals.

[0078] Final structure: The surface is a nanocrystalline Mn-rich area with grains ≤100nm, and the core is a coarse columnar Mn-depleted area with grains ≤10μm;

[0079] The manganese-copper alloy is obtained by sequentially performing annealing treatment and surface nano-crystallization treatment. During the annealing treatment, the alloy after the strong magnetic treatment is placed in an annealing furnace and annealed for 2 hours at a temperature of 600° C. under argon protection conditions.

[0080] The surface nano-crystallization treatment is performed on the annealed alloy by using supersonic projectile technology, wherein the supersonic projectile is a 0.3 mm projectile, the pressure of the compressed gas is 6 bar, and a single treatment takes 20 minutes.

[0081] Comparative Example

[0082] Manganese-copper alloy model 6J13.

[0083] The manganese-copper alloys of Examples 1 to 4 and the comparative example were subjected to tensile performance tests and impact toughness tests, respectively. The tensile performance test was performed by performing a quasi-static tensile test on a universal testing machine to measure the stress-strain curve to obtain the tensile strength and yield strength; the impact toughness test was performed by performing a Charpy impact test and a three-point bending test to obtain the dynamic fracture toughness and crack propagation resistance of the material, respectively. The results are shown in Table 1 below.

[0084] Table 1

[0085]

[0086] As can be seen from the above table, the data of Examples 1 to 4 show that Example 2 is the best embodiment of the present invention. Comparing the test data of Examples 1 to 4 with the test data of the comparative example, it can be seen that the manganese-copper alloy prepared by the present invention has greatly improved strength and toughness compared to the manganese-copper alloy in the prior art, and can meet the demanding requirements for its application in technical fields such as aerospace and automobile manufacturing.

[0087] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a gradient composition of a manganese-copper alloy with improved toughness, characterized in that: The following steps are involved: The copper powder and manganese powder are uniformly mixed into surface powder and core powder, and the feeding ratio of the surface powder and the core powder is dynamically adjusted by a double powder feeder; During the feeding process, the manganese content in the feed is adjusted by laser sintering with each layer deposited through a double powder feeder; After sintering is completed, a strong axial magnetic field is applied to drive the Mn atoms to migrate to the tail of the molten pool to form a composition gradient strengthening; Performing annealing treatment and surface nano-crystallization treatment in sequence to obtain a manganese-copper alloy; Wherein, the surface layer powder comprises: copper powder and 24-26wt% manganese powder; The core powder comprises: copper powder and 4-6 wt% manganese powder; During the laser sintering process, the thickness of the deposited layer in a single deposition is 25-35 μm, and the manganese content between the deposited layers increases from the core layer to the surface layer, with the manganese content of each layer increasing by 3-6 wt%.

2. The method for preparing a gradient composition of a manganese-copper alloy with improved toughness according to claim 1, characterized in that: During the laser sintering process, the laser wavelength is 1070 nm, the laser spot diameter is 45-55 μm, the laser scanning power is 300-500 W, and the laser scanning speed is 800-1200 mm / s; Laser sintering is performed layer by layer from the core layer to the surface layer, and the inter-layer rotation scanning direction is 67°.

3. The method for preparing a gradient composition of a manganese-copper alloy with improved toughness according to claim 1, wherein: The magnetic field strength is 11-13 T, and the magnetic field direction is parallel to the deposition direction during the sintering process.

4. The method for preparing a gradient composition of a manganese-copper alloy with improved toughness according to claim 1, wherein: While applying the magnetic field, the sintered alloy is cooled at a rate of 0.5-2°C / s.

5. The method for preparing a gradient composition of a manganese-copper alloy with improved toughness according to claim 1, wherein: The annealing treatment specifically includes placing the alloy after the strong magnetic treatment in an annealing furnace and annealing it at a temperature of 600° C. for 2 hours under argon protection conditions.

6. The method for preparing a gradient composition of a manganese-copper alloy with improved toughness according to claim 1, wherein: The surface of the annealed alloy is nano-treated using supersonic projectile technology, wherein the supersonic projectile is a projectile of 0.1-0.5 mm, the pressure of the compressed gas is 4-8 bar, and a single treatment time is 5-30 minutes.

7. A manganese-copper alloy with improved toughness, characterized in that: A manganese-copper alloy prepared according to any one of claims 1 to 6.

8. An application of a manganese-copper alloy with improved toughness, characterized in that: The manganese-copper alloy prepared according to any one of claims 1 to 6 is used in the fields of aerospace and automobile manufacturing.

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