Process for preparing surface component gradient high-purity copper-manganese alloy plate blank based on electron beam selective volatilization

Abstract

The invention discloses a process for preparing a surface component gradient high-purity copper-manganese alloy plate blank based on electron beam selective volatilization, which is characterized in that electron beams are used for accurately controlling volatilization of manganese under high vacuum, the electron beams are used as a processing means, and the surface of a formed homogeneous copper-manganese alloy plate blank is used as a processing area; melting the surface layer of the plate blank according to preset electron beam scanning parameters to form a shallow and controllable molten pool, and carrying out gradient programming of components and tissues on the plate blank in space, so that the surface of the plate blank is a manganese-poor or pure copper layer with specific functions (such as high conductivity and corrosion resistance), and the middle is a gradient layer with continuous component transition; and the core part is the copper-manganese alloy matrix layer which keeps the original strength and plasticity, and finally the gradient functional material with continuously changed components / properties is formed, so that the cost is reduced, the process is simple, and the application range of the homogeneous copper-manganese alloy is expanded.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a process for preparing high-purity copper-manganese alloy slabs with surface composition gradients based on electron beam selective evaporation. Background Technology

[0002] Homogeneous high-purity copper-manganese alloys are a key high-performance functional material widely used in precision resistors. By precisely controlling the solid solubility of manganese in the copper matrix (typically with manganese content controlled within the range of 5-30 wt.%), the resistivity and temperature coefficient of resistance of the alloy can be systematically altered. For example, "manganese-copper" alloys with a manganese content of approximately 11-13 wt.% exhibit extremely low temperature coefficient of resistance (α≈±10×10⁻⁶) near room temperature. -6 Manganese, with its high temperature coefficient of resistance (TCR) and long-term stability, is widely used in the manufacture of standard resistors, bridge arms, and shunts in high-precision measuring instruments. The addition of manganese, through solid solution strengthening, causes lattice distortion, significantly increasing electron scattering, thereby raising the resistivity to tens of times that of pure copper while maintaining good machinability. In the field of corrosion-resistant materials, single-phase solid solution alloys formed by adding approximately 20-30 wt.% manganese can form a dense and self-healing manganese oxide protective film on the surface, exhibiting far superior corrosion resistance to ordinary brass or stainless steel in seawater, acidic media, and high-temperature steam environments. It is commonly used in the manufacture of ship fittings, chemical valves, and heat exchanger piping. All of these applications require uniform distribution and controllable content of manganese in the copper matrix. Even a small deviation in manganese content (such as ±0.5 wt.%) can lead to a drastic change in the temperature coefficient of resistance or uneven precipitation of the corrosion-resistant phase, directly resulting in substandard device performance.

[0003] As application environments become more complex, the requirements for homogeneous copper-manganese alloys are becoming more stringent, such as high conductivity and high strength. However, the microstructure required for these two properties is contradictory. A common method is to composite plates with different manganese contents. This method requires pre-preparing plates with the required manganese content according to the needs, and then compositing them. This process is complex and costly, and needs to be improved. Summary of the Invention

[0004] To address at least one of the aforementioned technical deficiencies, the present invention provides the following technical solution:

[0005] This application discloses a process for preparing high-purity copper-manganese alloy slabs with surface composition gradients based on selective electron beam volatilization, including the step of scanning a homogeneous copper-manganese alloy slab with an electron beam in a vacuum induction furnace, and the manganese content of the high-purity copper-manganese alloy slab being gradient-distributed in the thickness direction through manganese volatilization.

[0006] For example, electron beam scanning can be performed on the entire slab or a selected area.

[0007] Furthermore, the vacuum induction melting parameters are as follows: vacuum degree 0.2-3×10 -3 Pa, electron beam power 30-100KW, beam spot diameter 1-4mm, scanning speed 200-500mm / s, scanning spacing 0.4-2mm, bidirectional grating repeated scanning 1-8 times, control time 1-5min.

[0008] Furthermore, the parameters of the homogeneous copper-manganese alloy slab are as follows: by mass, Mn content > 1%, oxygen content < 5 ppm, carbon content < 10 ppm, and the content of other individual impurity elements is all below 5 ppm.

[0009] Furthermore, the pressure rise rate inside the furnace during vacuum induction melting is <1 Pa / h.

[0010] Furthermore, the voltage is 25-45KV and the current is 300-650mA.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses electron beam to precisely control the volatilization of manganese under high vacuum as a processing method. The surface of a pre-formed homogeneous copper-manganese alloy slab is used as the processing area. The surface layer of the slab is melted according to preset electron beam scanning parameters to form a shallow and controllable molten pool. The slab is spatially programmed with a gradient in composition and structure, so that the surface of the slab is a manganese-poor or pure copper layer with specific functions (such as high conductivity and corrosion resistance), the middle is a gradient layer with continuous compositional transition, and the core is a copper-manganese alloy matrix layer that maintains the original strength and plasticity. Finally, a gradient functional material with continuously changing composition / performance is formed, which reduces costs, simplifies the process, and helps to expand the application range of homogeneous copper-manganese alloys. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a diagram of the copper-manganese alloy plate prepared in Example 1; Figure 2 This is a regional division diagram of the molded ingot in Comparative Example 1. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0015] Example 1 A process for preparing high-purity copper-manganese alloy slabs with surface composition gradients based on electron beam selective volatilization includes a step of scanning a homogeneous copper-manganese alloy slab with an electron beam in a vacuum induction furnace, wherein the manganese content of the high-purity copper-manganese alloy slab is gradient-distributed in the thickness direction through manganese volatilization.

[0016] The homogeneous copper-manganese alloy slab has the following composition by mass: manganese content is 20wt / %, oxygen content is 2ppm, carbon content is 8ppm, and the content of other individual impurity elements (such as Fe 4ppm, Ni 3ppn, Cr 3ppm) is less than 5ppm. The remainder is copper. The purity of the copper raw material in the slab is 99.9999%, the purity of the manganese raw material is 99.995%, and the length, width and height dimensions are 400mm×200mm×30mm.

[0017] The homogeneous copper-manganese alloy slab was placed in a square crucible inside an EB furnace, and the furnace chamber was sealed. A vacuum was then evacuated until the vacuum level inside the furnace reached 1.0 × 10⁻⁶. -3 Electron beam melting begins at 30 kV voltage and 500 mA, with an internal pressure rise rate of 0.5 Pa / h and an internal pressure rise rate of 0.5 Pa / h. The electron beam power is 9 kW, the beam spot diameter is 1.5 mm, the scanning speed is 600 mm / s, and the scanning interval is 0.5 mm. A bidirectional grating scans the top surface of the slab twice, with each scan lasting 5 minutes. After scanning, the slab is cooled to room temperature in the furnace before being removed from the furnace.

[0018] Example 2 Compared with Example 1, the differences are as follows: the electron beam power is 20KW, the beam spot diameter is 2.5mm, the scanning speed is 500mm / s, the scanning interval is 0.4mm, bidirectional scanning is performed 4 times, and the single scan time is 5min. All other parameters are the same as in Example 1.

[0019] Example 3 The difference from Example 1 is that the electron beam power is 12 kW. All other parameters are the same as in Example 1.

[0020] Example 4 The difference from Example 1 is that the electron beam power is 16 kW. All other parameters are the same as in Example 1.

[0021] Comparative Example 1 Manganese flakes with a purity of 99.995% are evenly spread on a copper plate of specified size and a purity of 99.9999% on the EB furnace's charge box according to a specified ratio. The ingot derrick is made of copper and has a diameter of 300mm. After sealing the furnace chamber, a vacuum is drawn until the vacuum level inside the furnace reaches 1.0 × 10⁻⁶. -3The furnace pressure rise rate was 0.5 Pa / h, and a dual-gun melting process was carried out under the conditions of 30 kV voltage and 7 A current. The first electron gun was used to melt the billet, and the second electron gun was used to refine the copper-manganese alloy solution molten in the water-cooled copper crucible. The power of the first electron gun was 250 kW, and the power of the second electron gun was 210 kW. The distance between the electron gun and the edge of the crucible was 15 mm during on-site beam drawing. The average material flow height was 20 mm / min each time, and the total melting time was 2.5 h. After cooling in the furnace, the product was removed from the furnace. The composition of the prepared plate is as follows: by mass, the manganese content is 20 wt%, the oxygen content is 3 ppm, the carbon content is 7 ppm, the content of other individual impurity elements (such as Fe, Ni, Cr) is less than 5 ppm, and the remainder is copper.

[0022] The copper-manganese alloy plates prepared above were tested. Fifteen samples of different thicknesses from left to right were randomly selected from Example 1 and Example 2 using an electron probe microanalyzer. The following data were obtained, as shown in Table 1.

[0023] Table 1

[0024] Conclusion: ① The gradient layer thickness of the board prepared in Example 1 is about 0.8 mm, and the gradient layer thickness of the board prepared in Example 2 is about 1.5 mm.

[0025] ② The minimum manganese content of the surface layer of the plate prepared in Example 1 was reduced to 3.7 wt%, and the minimum manganese content of the surface layer of the plate prepared in Example 2 was reduced to 1.3 wt%, which is close to that of pure copper layer.

[0026] ③ The composition of the plate prepared at a depth > 1.5 mm was restored to the original value of 20 wt% of manganese.

[0027] ④ The detection data from Examples 1 and 2 clearly show that the manganese content exhibits a gradual gradient change trend in different regions, and the manganese content in the same thickness layer is uniformly distributed.

[0028] The copper-manganese alloy plates prepared above were tested. Different depths of Example 1 and Example 2 were randomly tested using an eddy current tester, and the following data were obtained, as shown in Table 2.

[0029] Table 2

[0030] Conclusion: The electrical conductivity of the plates prepared in Examples 1 and 2 exhibits different gradual changes at different depths, but both show a decreasing trend. The surface electrical conductivity of the plate prepared in Example 2 is infinitely close to 100%, while that of the matrix is ​​stable at around 20%, proving that the electron beam melting gradient copper-manganese alloy slab is feasible.

[0031] The manganese content of the copper-manganese alloy ingot formed by conventional electron beam melting in Comparative Example 1 was determined using ICP-OES. The ingot was cut in half along the aforementioned black line, and divided into 80 regions in total, longitudinally (H1-H16) and laterally (AE). See [reference needed]. Figure 2 The test results are shown in Table 3.

[0032] Table 3

[0033] Conclusion: The data in Table 3 shows that the manganese content in copper-manganese alloy ingots produced by traditional electron beam melting has no regularity in either the longitudinal or transverse direction. Some areas show severe volatilization, while others show manganese enrichment. This verifies that homogeneous ingots cannot be produced by using a single electron beam melting process.

[0034] The data in Table 4 are obtained by testing the plates prepared in Examples 3 and 4 using a surface roughness measuring instrument and a direct-reading spectrometer.

[0035] Table 4

[0036] Conclusion: Increasing the electron beam power leads to a thicker gradient layer and a decreasing trend in surface Mn content, but excessively high power can easily lead to a decrease in the surface quality of copper-manganese alloy slabs.

[0037] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A process for preparing high-purity copper-manganese alloy slabs with surface composition gradients based on electron beam selective volatilization, characterized in that, The process includes scanning a homogeneous copper-manganese alloy slab with an electron beam in a vacuum induction furnace, and allowing the manganese content of the high-purity copper-manganese alloy slab to be distributed in a gradient along the thickness direction through manganese volatilization.

2. The process for preparing high-purity copper-manganese alloy slabs with surface composition gradients based on electron beam selective volatilization as described in claim 1, characterized in that: The parameters for vacuum induction melting are as follows: vacuum degree 0.2-3×10 -3 Pa, electron beam power 30-100KW, beam spot diameter 1-4mm, scanning speed 200-500mm / s, scanning interval 0.4-2mm, bidirectional grating repeated scanning 1-8 times, control time 1-5min.

3. The process for preparing high-purity copper-manganese alloy slabs with surface composition gradients based on electron beam selective volatilization as described in claim 1, characterized in that: The parameters of the homogeneous copper-manganese alloy slab are as follows: by mass, Mn content > 1%, oxygen content < 5 ppm, carbon content < 10 ppm, and the content of other individual impurity elements is all less than 5 ppm.

4. The process for preparing high-purity copper-manganese alloy slabs with surface composition gradients based on electron beam selective volatilization as described in claim 1, characterized in that: The pressure rise rate inside the furnace during vacuum induction melting is <1 Pa / h.

5. The process for preparing high-purity copper-manganese alloy slabs with surface composition gradients based on electron beam selective volatilization as described in claim 1, characterized in that: Voltage 25-45KV, current 300-650mA.

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