A method for preparing amorphous pure metal material

Abstract

The present invention discloses a method for preparing an amorphous pure metal material, comprising the following steps: preparing a pure metal material in a polycrystalline or single crystal state, then pre-processing the surface of the pure metal material so that the surface roughness of the pure metal material is no greater than Sa 1.6 μm; using a polycrystalline diamond tool to perform rough cutting on the end face of the metal material; using a single crystal diamond tool to perform fine processing on the metal material; quickly removing the finely processed pure metal material from an ultra-precision machine tool and storing it in a vacuum environment or a protective gas atmosphere that does not chemically react with the pure metal material, wherein the finely processed pure metal material contains amorphous crystals and has an amorphous layer on the surface of the processed pure metal material. By using an extremely sharp single crystal diamond tool to perform ultra-precision cutting on the pure metal material, utilizing the extremely high shear strain and strain rate generated during the cutting process, an amorphous pure metal structure is obtained in the surface layer and sub-surface layer.

Description

Technical Field

[0001] The present invention relates to a method for preparing a metal material, in particular to a method for preparing an amorphous pure metal material. Background Art

[0002] Amorphous material is a material with long-range disorder of its constituent atoms. Amorphous metal material is an important amorphous material. Compared with traditional polycrystalline / single crystal metal materials, amorphous metal materials have many advantages such as high strength, high toughness, high hardness, etc., and are a key material for future applications. At present, most amorphous metal materials are alloys, and the preparation of amorphous metal materials mainly adopts the method of rapid cooling. This is because the amorphization ability (the ability to transform from a polycrystalline state to an amorphous state) of pure metal (pure metal refers to metal without other impurities or other metal components) is very weak, and it requires extreme conditions to form an amorphous state (such as extremely high cooling rate: 10 11 ~10 13 K / s). To improve the amorphization ability of metal materials, different metal elements need to be added to reduce the critical cooling rate of the metal material's amorphization. For example, patent CN118581375A discloses a six-element high-entropy amorphous alloy, its preparation method, and application. The amorphous metal material prepared by this method contains six different metal elements and requires a melt spinning method to achieve extremely high cooling rates. The patent specifically mentions that if the metal melt is not cooled quickly enough, crystallization is likely to occur, which is not conducive to the formation of an amorphous alloy.

[0003] Existing technologies for producing amorphous metals require very high cooling rates, placing high demands on processing equipment. Under these conditions, it is difficult to produce large areas of pure amorphous metals due to the extremely high critical cooling rate for amorphization of pure metals. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing an amorphous pure metal material that can achieve amorphization of various pure metals.

[0005] The technical solution adopted by the present invention to solve the above technical problems is:

[0006] A method for preparing an amorphous pure metal material of the present invention comprises the following steps:

[0007] Step 1: prepare a pure metal material in a polycrystalline or single crystal state, and then pre-process the surface of the pure metal material so that the surface roughness of the pure metal material is not greater than Sa 1.6 μm;

[0008] Step 2: Fix the pure metal material on an ultra-precision machine tool, adjust the dynamic balance parameters of the ultra-precision machine tool spindle to within 30nm, and use a polycrystalline diamond tool to perform rough cutting on the end face of the metal material. During the rough cutting process, a cooling and dry protective gas is continuously sprayed on the cutting area to prevent the prepared amorphous pure metal material from being oxidized;

[0009] Step 3: After the rough machining is completed, the dynamic balance parameters of the ultra-precision machine tool spindle are readjusted to within 30nm, and then the metal material is fine-machined using a single crystal diamond tool, and the protective gas used in step 2 is continuously sprayed on the cutting area;

[0010] Step 4: Quickly remove the finely processed pure metal material from the ultra-precision machine tool and store it in a vacuum environment or a protective gas atmosphere that does not chemically react with the pure metal material. The finely processed pure metal material contains amorphous materials, and an amorphous layer is formed on the surface of the processed pure metal material.

[0011] The beneficial effects of the present invention are:

[0012] By using a single crystal diamond tool with a large arc blade (the radius of the blade tip is not less than 5mm) and extremely sharp (the blunt radius of the cutting edge is not more than 20nm) to perform ultra-precision cutting of pure metal materials at an extremely small feed rate (the feed rate per revolution generally does not exceed 2μm / r), and utilizing the extremely high shear strain and extremely high strain rate generated during the cutting process, amorphous pure metal structure is obtained in the surface and sub-surface layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a bright field image of the subsurface structure of pure copper after processing. The black part in the picture is the protective layer, the white bright band is the amorphous layer, and below the amorphous layer is polycrystalline pure copper, among which the white dot-shaped area is the amorphous island structure of pure copper.

[0014] Figure 2 This is the result of high-resolution observation between the interface of amorphous copper and polycrystalline copper. The amorphous copper has atoms that are randomly distributed, while the polycrystalline copper has atoms that are regularly distributed. There are stacking faults in the polycrystalline copper.

[0015] Figure 3 This is the fast Fourier transform result of the amorphous copper area. The diffuse amorphous ring results in the figure show that through effective oxygen isolation protection measures, amorphous pure copper appears on the surface and inside of the pure copper after fine processing.

[0016] Figure 4 This is a brightfield image of the subsurface structure of pure aluminum after processing. The black portion in the image is the protective layer, and the white area is amorphous aluminum. Amorphous aluminum is distributed not only on the surface of the material but also in the adiabatic shear bands within the material.

[0017] Figure 5 It is a high-resolution result of amorphous aluminum inside the material. The one with regular distribution of atoms is polycrystalline aluminum, and the one with disordered distribution of atoms is amorphous aluminum.

[0018] Figure 6 This is the bright field image of the pure magnesium subsurface structure after processing. The white box area is the amorphous magnesium area.

[0019] Figure 7 It is the transition region between polycrystalline magnesium and amorphous magnesium.

[0020] Figure 8 It is a completely amorphous magnesium region.

[0021] Figure 1-8 All images were obtained using a transmission electron microscope Talos F200. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] A method for preparing an amorphous pure metal material of the present invention comprises the following steps:

[0024] Step 1: Prepare pure metal materials in a polycrystalline or single crystal state, and then pre-process the surface of the pure metal material so that the surface roughness of the pure metal material is not greater than Sa 1.6μm, so as to facilitate subsequent rough processing and fine processing.

[0025] The preferred pure metal material is: the mass percentage of the main elements of the pure metal material is not less than 99%, and the balance is the content of impurity elements. The method of pre-processing the surface of the pure metal material is: using a grinding or polishing method.

[0026] Step 2: Fix the pure metal material on the ultra-precision machine tool, and adjust the dynamic balance parameters of the ultra-precision machine tool spindle to within 30nm. Use a polycrystalline diamond tool to perform rough cutting on the end face of the metal material. During the rough cutting process, coolant cannot be sprayed on the metal material to prevent the introduction of impurity elements, and the cutting area must be continuously sprayed with cooling (generally the temperature range is: -20°C to 20°C) and drying (the mass percentage of water content is less than 0.1%) protective gas to prevent oxidation of the prepared amorphous pure metal material. The protective gas cannot react chemically with the pure metal material. For example, for pure copper processing, nitrogen or argon is selected as the protective gas; for non-ferrous metal processing such as pure aluminum and pure magnesium, argon is selected as the protective gas. The radius of the tool tip arc is generally required to be not less than 5mm, so that a smooth surface with low roughness can be obtained, reducing the difficulty of subsequent fine processing.

[0027] The preferred roughing process parameters are: ultra-precision machine tool spindle speed 1000-3000 rpm, cutting depth 3-15 μm, and feed rate per revolution 10-30 μm / r. This can increase the metal removal rate, reduce processing time, and improve processing efficiency.

[0028] Step 3: After the rough machining is completed, the dynamic balance parameters of the ultra-precision machine tool spindle are readjusted to within 30nm, and then the metal material is fine-machined using a single crystal diamond tool, and the protective gas in step 2 is continuously sprayed on the cutting area.

[0029] The preferred finishing parameters are: spindle speed 2000 rpm, cutting depth 1-2 μm, and feed rate 0.5-2 μm / rev. This improves the metal removal rate, increases the shear strain in the cutting area, promotes the amorphization of pure metal materials, and produces a smooth surface with low roughness.

[0030] The preferred parameters for single crystal diamond cutting tools are: a tool tip radius of no less than 5 mm, and a tool cutting edge blunt radius of no more than 20 nm. This can increase the shear strain in the cutting area and promote the amorphization of pure metal materials.

[0031] Step 4. Quickly remove the finely processed pure metal material from the ultra-precision machine tool and store it in a vacuum environment or in a protective gas atmosphere that cannot chemically react with the pure metal material. The method of selecting the protective gas is similar to that of steps 2 and 3. For example, cooled and dried nitrogen or argon can be used to preserve pure copper, and cooled and dried argon can be used to protect pure aluminum, pure magnesium and other non-ferrous metals. The finely processed pure metal material contains amorphous materials, and there is an amorphous layer on the surface of the pure metal material after processing. The thickness of the amorphous layer is 10 to 30 nm; the hardness of the finely processed pure metal material is 2 to 4 times that of the pure metal material before processing.

[0032] Example 1

[0033] The present invention is described by taking pure copper material as an example.

[0034] Step 1: Select high-conductivity oxygen-free pure copper (purity ≥ 99.9%) as the metal material. The material is a cylindrical bar with a diameter of 30 mm and a height of 15 mm. Electrochemical mechanical polishing is performed on the surface of the pure copper material. After polishing, the surface roughness is measured to be Sa 18.69 nm.

[0035] Step 2: Rough machining of pure copper was performed using a Nanoform 250 ultra-precision machining center, with the spindle's dynamic balance adjusted to within 30 nm. A polycrystalline diamond tool with a 5 mm tip radius was used for rough machining. The rough machining parameters were: spindle speed of 1200 rpm, depth of cut of 10 μm, and feed rate of 10 μm / rev. Dry machining (without any cutting fluid) was used for rough machining of the pure copper. Simultaneously, pure nitrogen was continuously sprayed into the cutting area to cool (10°C) and dry (moisture content less than 0.05%) the machined surface.

[0036] Step 3: A Nanoform 250 ultra-precision machining center was used to finish-machine the pure copper, adjusting the spindle's dynamic balance parameters to within 30 nm. The finishing tool used was a natural single-crystal diamond tool with a 10 mm tip radius and a 10.3 nm cutting edge radius. The finishing process parameters were: spindle speed of 2000 rpm, depth of cut of 2 μm, and feed per revolution of 2 μm / rev. During the finishing of the pure copper, dry cutting was employed, while the cutting area was continuously sprayed with pure nitrogen to cool (10°C) and dry (moisture content less than 0.05%) the machined surface.

[0037] Step 4: Remove the processed pure copper material from the machine tool quickly and store it in a vacuum tank. Use transmission electron microscopy to analyze the surface and subsurface of the processed pure copper. The results are as follows: Figure 1 、 2 and 3. Figure 1 The protective layer, amorphous copper, and polycrystalline copper of the transmission sample are marked in the figure. The amorphous copper is located between the protective layer and the polycrystalline copper, and its thickness is approximately 30nm. In addition to the surface layer, the white contrast spots within the polycrystalline copper are islands of polycrystalline copper (marked as amorphous islands in the figure). Figure 2 The transition between polycrystalline copper and amorphous copper is shown, where atoms are regularly distributed in polycrystalline copper and disordered in amorphous copper. Figure 3The Fourier transform results of the amorphous copper region are shown. The diffuse amorphous rings in the figure indicate that effective oxygen isolation protection measures have led to the appearance of amorphous copper on the surface and within the pure copper after fine processing. Nanoindentation was used to measure the hardness of the pure copper before and after processing. The average hardness of the pure copper before processing was 1.20 GPa, and the hardness after fine processing was 4.80 GPa, which is four times the hardness before processing.

[0038] Example 2

[0039] The present invention is described by taking pure aluminum material as an example.

[0040] Step 1: The workpiece material is pure aluminum (purity ≥ 99.9%), and the workpiece is a cylindrical bar with a diameter of 30 mm and a height of 15 mm. The pure aluminum material is electrochemically mechanically polished, and the surface roughness after polishing is measured to be Sa 25.1 nm.

[0041] Step 2: A Nanoform 250 ultra-precision machining center was used, and the spindle dynamic balance parameters were adjusted to within 30 nm. A polycrystalline diamond tool with a 5 mm tip radius was used for roughing. The roughing process parameters were: spindle speed 1200 rpm, depth of cut 10 μm, and feed rate 10 μm / rev. During the roughing process of pure aluminum, dry cutting was performed (without any cutting fluid). Simultaneously, the cutting area was continuously sprayed with dry (moisture content less than 0.05%) pure argon gas (temperature: 10°C) to protect the machined surface.

[0042] Step 3: A Nanoform 250 ultra-precision machining center was selected as the processing equipment, and the dynamic balance parameters of the spindle were adjusted to within 30 nm. The finishing tool used was a natural single-crystal diamond tool with a tip radius of 10 mm and a cutting edge radius of 10.0 nm. The finishing process parameters were: spindle speed of 2000 rpm, depth of cut of 2 μm, and feed rate of 0.5 μm / rev. During the finishing process of pure aluminum, dry cutting was performed, and the cutting area was continuously sprayed with dry (moisture content less than 0.05%) pure argon gas (temperature: 10°C) to protect the machined surface.

[0043] Step 4: Remove the processed pure aluminum material from the machine tool quickly and store it in a vacuum tank. Use transmission electron microscopy to analyze the surface and subsurface of the processed pure aluminum. The results are as follows: Figure 4 and 5 shown. Figure 4 The image shows the distribution of the protective layer, amorphous aluminum, and polycrystalline aluminum. The white contrast indicates amorphous aluminum, which has a thickness of approximately 15 nm. Amorphous aluminum is distributed not only on the surface of the material but also in the adiabatic shear bands within the material. Figure 5 Shown Figure 4 High-resolution images of amorphous aluminum within the material. Polycrystalline aluminum exhibits a regular atomic distribution, while amorphous aluminum exhibits a disordered atomic distribution. The Fourier transform results in the lower left corner of the image demonstrate that pure amorphous aluminum was produced through effective oxygen isolation and finishing. Nanoindentation measurements of the pure aluminum's hardness before and after processing revealed an average hardness of 0.93 GPa before processing and 2.21 GPa after finishing, representing a hardness 2.38 times greater than before.

[0044] Example 3

[0045] The present invention is described by taking pure magnesium material as an example.

[0046] Step 1: The workpiece material is pure magnesium (purity ≥ 99.9%), and the workpiece is a cylindrical bar with a diameter of 10 mm and a height of 5 mm. The pure copper material is electrochemically mechanically polished, and the surface roughness after polishing is measured to be Sa 5.45 nm.

[0047] Step 2: A Nanoform 250 ultra-precision machining center was selected for processing, and the spindle dynamic balance parameters were adjusted to within 30 nm. A polycrystalline diamond tool with a 5 mm tip radius was used for roughing. The roughing process parameters were: spindle speed 1200 rpm, depth of cut 10 μm, and feed rate 10 μm / rev. During the roughing process of pure magnesium, dry cutting (without any cutting fluid) was employed, while the cutting area was continuously sprayed with dry (less than 0.05% moisture content) pure argon gas (temperature: 10°C) to protect the machined surface.

[0048] Step 3: A Nanoform 250 ultra-precision machining center was used as processing equipment, and the dynamic balance parameters of the spindle were adjusted to within 30 nm. The finishing tool used was a natural single-crystal diamond tool with a tip radius of 10 mm and a cutting edge radius of 15.0 nm. The finishing process parameters were: spindle speed of 2000 rpm, depth of cut of 2 μm, and feed rate of 0.5 μm / rev. During the finishing process of pure magnesium material, dry cutting was performed, and the cutting area was continuously sprayed with dry (moisture content less than 0.05%) pure argon gas (temperature: 10°C) to protect the machined surface.

[0049] Step 4: The processed pure magnesium material is quickly removed from the machine tool and stored in a vacuum tank. The surface and subsurface layers of the processed pure magnesium are analyzed using a transmission electron microscope. Figure 6 The internal structure of pure magnesium material after fine processing is shown. The thickness of amorphous magnesium is about 10 to 15 nm. The white box area in the figure is the amorphous area inside the material. Figure 7 The transition region between polycrystalline and amorphous magnesium is shown. Figure 8 A completely amorphous magnesium region is shown. Figure 7 and Figure 8 The Fourier transform results also confirmed the situation of polycrystalline-amorphous magnesium and amorphous magnesium. The hardness of pure magnesium before and after processing was further measured using a nanoindenter. The average hardness of pure magnesium before processing was 1.02GPa, and the hardness of pure magnesium after fine processing was 2.82GPa, which is 2.76 times the hardness before processing.

Claims

1. A method for preparing an amorphous pure metal material, characterized in that The following steps are involved: Step 1: prepare a pure metal material in a polycrystalline or single crystal state, and then pre-process the surface of the pure metal material so that the surface roughness of the pure metal material is not greater than Sa 1.6 μm; Step 2: Fix the pure metal material on an ultra-precision machine tool, adjust the dynamic balance parameters of the ultra-precision machine tool spindle to within 30nm, and use a polycrystalline diamond tool to perform rough cutting on the end face of the metal material. During the rough cutting process, a cooling and dry protective gas is continuously sprayed on the cutting area to prevent the prepared amorphous pure metal material from being oxidized; Step 3: After the rough machining is completed, the dynamic balance parameters of the ultra-precision machine tool spindle are readjusted to within 30nm, and then the metal material is fine-machined using a single crystal diamond tool, and the protective gas in step 2 is continuously sprayed on the cutting area; Step 4: Quickly remove the finely processed pure metal material from the ultra-precision machine tool and store it in a vacuum environment or a protective gas atmosphere that does not chemically react with the pure metal material. The finely processed pure metal material contains amorphous materials, and an amorphous layer is formed on the surface of the processed pure metal material.

2. The method for preparing an amorphous pure metal material according to claim 1, wherein: The thickness of the amorphous layer is 10 to 30 nm.

3. The method for preparing an amorphous pure metal material according to claim 2, wherein: The hardness of pure metal materials after fine processing is 2 to 4 times that of pure metal materials before processing.

4. The method for preparing an amorphous pure metal material according to any one of claims 1 to 3, characterized in that: The mass percentage of the main elements of pure metal materials shall not be less than 99%, and the remainder shall be the content of impurity elements.

5. The method for preparing an amorphous pure metal material according to any one of claims 1 to 3, characterized in that: The temperature range of the protective gas continuously sprayed to the cutting area for cooling and drying during the rough cutting process is: -20°C to 20°C, and the mass percentage of water content is less than 0.1%.

6. The method for preparing an amorphous pure metal material according to any one of claims 1 to 3, characterized in that: The tool tip arc radius during the rough cutting process is not less than 5 mm; the rough cutting process parameters are: ultra-precision machine tool spindle speed 1000-3000 r / min, cutting depth 3-15 μm, and feed per revolution 10-30 μm / r.

7. The method for preparing an amorphous pure metal material according to claim 6, characterized in that: The process parameters for finishing are: spindle speed 2000r / min, cutting depth 1-2μm, feed per revolution 0.5-2μm / r; tool tip arc radius not less than 5mm, tool cutting edge blunt radius not greater than 20nm.

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