A method for improving the strength and plasticity of amorphous alloys

Abstract

A method for improving the strength and plasticity of amorphous alloys, which relates to the field of amorphous alloy preparation. The present invention aims to solve the problems existing in the existing methods for improving the plasticity of amorphous alloys, such as high cost of ceramic particles, precise material ratio requirements, uncontrollable elemental melting loss, etc., which severely limit their engineering applications. Therefore, the present invention uses a high-purity graphite crucible equipped with medium-frequency induction melting technology to prepare amorphous alloys. During the melting process, it can force small atoms C in the high-purity graphite crucible to diffuse into the gaps between amorphous alloy atoms to form a solid solution, thereby increasing the free volume of shear bands and the degree of amorphousness. At the same time, based on the above method, the C increment of the amorphous alloy can be determined at a certain melting temperature and any melting time when melting the amorphous alloy with a high-purity graphite crucible, so that the required amorphous alloy samples can be prepared.

Description

Technical Field

[0001] The present invention relates to the field of amorphous alloy preparation, and particularly to a method for improving the strength and plasticity of amorphous alloys. Background Art

[0002] Bulk amorphous alloys combine the characteristics of metals and glasses and have unique physical, mechanical, and chemical properties, such as high strength, high hardness, and strong corrosion resistance. They have considerable development potential in the application field of engineering structural components. However, one of the biggest obstacles restricting their practical application and popularization is that they usually exhibit limited macroscopic plasticity during deformation, usually less than 1%, and are prone to catastrophic brittle fracture. The existing methods for improving the macroscopic plasticity of amorphous alloys are to introduce trace heterogeneous elements into the amorphous matrix to improve the plasticity of amorphous alloys, such as alloying methods of adding metal elements to the melt before casting, introducing particles or fibers as the second phase, or mechanical alloying of elemental powders, etc. Among all methods, the most commonly used is to introduce carbide ceramic particles or small-sized atoms into the amorphous matrix to adjust the macroscopic plasticity of amorphous alloys. However, although this method helps to improve the plasticity of amorphous alloys, this preparation method has characteristics such as high cost of ceramic particles, precise material ratio required, and uncontrollable elemental melting loss, which severely limits its engineering application. Therefore, there is an urgent need to seek a low-cost and technically stable forming method to effectively improve the strength and plasticity of amorphous alloys. Summary of the Invention

[0003] In view of this, the present invention provides a method for improving the strength and plasticity of amorphous alloys, which uses a high-purity graphite crucible equipped with medium-frequency induction melting technology to prepare amorphous alloys. During the melting process, small atoms C in the high-purity graphite crucible can be forced to diffuse into the interstitial spaces of the amorphous alloy, thereby increasing the free volume of shear bands and the degree of amorphousness.

[0004] The technical solution adopted by the present invention to solve the above technical problems is:

[0005] A method for improving the strength and plasticity of amorphous alloys, and the improvement process is shown in the following steps:

[0006] S1, Weigh each metal raw material according to the target atomic percentage, uniformly mix them to obtain an alloy sample, divide the alloy sample into multiple portions, and further divide the multiple alloy samples into M groups. The M groups of alloy samples are respectively placed in a medium-frequency induction furnace equipped with a high-purity graphite crucible. Before induction melting of each alloy sample, first evacuate the high-purity graphite crucible and fill it with high-purity argon; at the start of melting, set different melting temperatures for each group of alloy samples, and set different melting times for different alloy samples in each group, and mark the moment when the alloy sample is completely melted as the zero point of timing; after each alloy sample is melted, pour the molten alloys at different melting temperatures and melting times into a cooling mold for cooling, and successively obtain multiple amorphous alloy samples diffused with C elements;

[0007] S2. Obtain the C content C(t) of each amorphous alloy sample in S1;

[0008] S3. Determine the volume V of any alloy sample in S1, and derive the contact area S between this alloy sample and the inner surface of the high-purity graphite crucible;

[0009] S4. Obtain the maximum C solubility Cs of the interfacial reaction of the alloy sample at the above different melting temperatures;

[0010] S5. Based on the C content C(t) and the maximum C solubility Cs of each amorphous alloy sample, obtain the rate constant k at different melting temperatures:

[0011]

[0012] where Co is the initial C solubility of the alloy sample, and t is the melting time;

[0013] S6. Based on the rate constant k obtained in S5, the C increment of the alloy sample melted by the high-purity graphite crucible at any time can be obtained.

[0014] Further, the pressure of the high-purity argon gas filled in the high-purity graphite crucible in S1 is 0.4 MPa to 0.6 MPa.

[0015] Further, a boron nitride ceramic sleeve is provided outside the high-purity graphite crucible in S1 to protect the inductor.

[0016] Further, the cooling mold in S1 is a high-purity copper mold.

[0017] Further, in S2, the C content C(t) of each amorphous alloy sample is obtained by a carbon-sulfur analyzer.

[0018] Further, in S3, the volume V of the alloy sample is determined based on the weight and density of the alloy sample, and the contact area S between the alloy sample and the inner surface of the high-purity graphite crucible is determined based on the shape and size of the inner surface of the high-purity graphite crucible.

[0019] Further, the maximum C solubility Cs in S4 is obtained through the following steps:

[0020] S41. Arc-melt an alloy sample with the same metal composition and ratio as in S1 to obtain a button ingot sample;

[0021] S42. Remelt the button ingot sample obtained in S41 in a vacuum arc furnace, and suck-cast it into a high-purity copper mold by the suck-casting method for cooling and shaping. After machining, N solubility measurement samples with the same volume are obtained;

[0022] S43. Prepare N glass tubes and 2N high-purity carbon blocks. Divide the 2N high-purity carbon blocks into N groups evenly. Each group of high-purity carbon blocks corresponds to a solubility measurement sample and a glass tube. Place one of the high-purity carbon blocks, the solubility measurement sample, and the other high-purity carbon block in each group into the corresponding glass tube in sequence.

[0023] S44. Evacuate the glass tubes filled with high-purity carbon blocks and solubility measurement samples, and then fill them with high-purity argon gas and seal the tubes.

[0024] S45. Divide the N glass tubes in S44 into M groups evenly. Place the M groups of glass tubes in a muffle furnace respectively, and heat and keep them warm at different heating temperatures. The holding time of the glass tubes in each group is different, so that different degrees of interfacial reactions occur between the solubility measurement samples and the high-purity graphite blocks. The heating temperature of the glass tubes in each group corresponds one-to-one to the melting temperature of each group of alloy samples in S1.

[0025] S46. When each glass tube reaches the holding time, take out the glass tube from the muffle furnace, break the glass tube and take out the solubility measurement sample dissolved with C element, and measure the carbon content of the solubility measurement sample by a carbon-sulfur analyzer. After measuring the carbon contents of all solubility measurement samples, the maximum C solubility Cs of the interfacial reaction at different melting temperatures can be obtained.

[0026] Furthermore, the pressure of the high-purity argon gas in S44 is 0.4 - 0.6 MPa.

[0027] Furthermore, the glass tubes in S45 are vertically placed into the muffle furnace to ensure that the high-purity carbon blocks and the solubility measurement samples can be in full contact.

[0028] Furthermore, the holding time of each glass tube in each group of glass tubes in S44 increases according to a geometric sequence with a common ratio of 2, and the starting holding temperature is 0.5 h.

[0029] The beneficial effects of the present invention compared with the prior art are as follows:

[0030] 1. The present invention uses a high-purity graphite crucible equipped with intermediate frequency induction melting technology to prepare amorphous alloys. During the melting process, it can force small atoms C in the high-purity graphite crucible to diffuse into the gaps between amorphous alloy atoms to form a solid solution, thereby increasing the shear band free volume and the degree of amorphousness. At the same time, based on the above method, the C increment of the amorphous alloy at a certain melting temperature and any melting time during the melting of the high-purity graphite crucible can be determined, so that the required amorphous alloy samples can be prepared.

[0031] 2. The method for improving the strength and plasticity of amorphous alloys in the present invention is technically stable, low in cost, and low in energy consumption, and can effectively improve the strength and plasticity of amorphous alloys.

[0032] 3. The method for improving the strength and plasticity of the amorphous alloy of the present invention is also applicable to alloys with different compositions and metal ratios, and is also applicable to the diffusion of different elements. For example, melting the amorphous alloy in a quartz crucible to force the O element to diffuse into the interstitial spaces of the amorphous alloy to strengthen the amorphous alloy by solid solution strengthening or forming a crystal phase, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings, as a part of this application, are used to provide a further understanding of the present invention.

[0034] Figure 1 It is a schematic diagram of the state when sealing the glass tube containing the high-purity carbon block and the solubility measurement sample.

[0035] Figure 2 It is a schematic diagram of the structure of the high-purity graphite crucible in Example 1.

[0036] Figure 3 For different melting temperatures in Example 1 The coordinate system of t.

[0037] Figure 4 It is a schematic diagram of the results of the compressive strength and plasticity of each amorphous alloy sample after performing a uniaxial compression test on the amorphous alloy samples at different melting temperatures and melting times.

[0038] Figure 5 It is a schematic diagram of the results of the shear band volume of each amorphous alloy sample after performing a nanoindentation test on the amorphous alloy samples at different melting temperatures and melting times.

[0039] Explanation of reference numerals: 1 - solubility measurement sample; 2 - high-purity carbon block; 3 - glass tube. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The following provides a detailed description of the present invention in combination with specific embodiments.

[0041] This embodiment provides a method for improving the strength and plasticity of an amorphous alloy, and the improvement process is as follows:

[0042] S1. Weigh each metal raw material according to the target atomic percentage. All the metal raw materials are high-purity raw materials. Uniformly mix the metal raw materials to obtain an alloy sample, and divide the alloy sample into multiple portions. The multiple alloy samples are further divided into M groups, where M is an integer greater than or equal to 3, that is, at least 3 test groups are formed. The M groups of alloy samples are respectively placed in an intermediate-frequency induction furnace equipped with a high-purity graphite crucible. Before induction melting of each alloy sample, first evacuate the high-purity graphite crucible and fill it with high-purity argon gas at 0.4 MPa to 0.6 MPa to avoid oxidation reaction of the alloy sample during the melting process. At the start of melting, set different melting temperatures for each group of alloy samples, that is, the M groups of alloy samples correspond to M melting temperatures, and set different melting times for different alloy samples in each group. And take the moment when the alloy sample is completely melted as the zero point of timing, so that the influence of melting temperature and melting time on the diffusion amount of small atom C in the high-purity graphite crucible can be determined. During the process of melting the alloy using the high-purity graphite crucible, it can force the small atom C to diffuse and dissolve into the interstitial spaces composed of amorphous alloy atoms, thereby increasing the free volume of the shear band and increasing the degree of amorphousness. After melting each alloy sample is completed, pour the molten alloy into a high-purity copper mold to cool, and successively obtain multiple amorphous alloy samples with C element diffused therein;

[0043] S2. After all the alloy samples are melted and cooled, obtain the C content C(t) of each amorphous alloy sample in S1 through a carbon-sulfur analyzer;

[0044] S3. Determine the volume V of a certain alloy sample based on its weight and density, and determine the contact area S between this alloy sample and the inner surface of the high-purity graphite crucible based on the shape and size of the inner surface of the high-purity graphite crucible. Since the volume and weight of each alloy sample are the same, it is only necessary to measure the volume V of one alloy sample and the contact area S between this alloy sample and the inner surface of the high-purity graphite crucible;

[0045] S4. Directly obtain the maximum C solubility Cs of the interfacial reaction of alloy samples with the same metal composition and ratio as those in S1 at the above-mentioned M different melting temperatures by the method of diffusing small-sized C atoms into the amorphous alloy. Obtain the relationship between the C solubility, melting time, and melting temperature in the alloy sample from the maximum C solubility Cs. The steps for obtaining the maximum C solubility Cs are as follows:

[0046] S41. Weigh each metal raw material with the same metal composition and ratio as those in S1. All the metal raw materials are also high-purity raw materials. Uniformly mix the metal raw materials to obtain alloy sample two, and obtain a high-purity button ingot sample by arc melting alloy sample two;

[0047] S42. Remelt the high-purity button ingot sample obtained in S41 in a vacuum arc furnace, and then use the suction casting method to cast it into a rectangular high-purity copper mold for cooling and shaping. After machining, N solubility measurement samples 1 with the same volume are obtained;

[0048] S43. Prepare N glass tubes 3 and 2N high-purity carbon blocks 2. Divide the 2N high-purity carbon blocks 2 into N groups, with each group of high-purity carbon blocks 2 corresponding to a solubility measurement sample 1 and a glass tube 3. In sequence, place one of the high-purity carbon blocks 2, the solubility measurement sample 1, and another high-purity carbon block 2 in each group into the corresponding glass tube 3, where the high-purity carbon block 2 directly provides small-sized C atoms for the solubility measurement sample 1;

[0049] S44. Vacuumize the glass tube 3 filled with the high-purity carbon block 2 and the solubility measurement sample 1, and then fill it with high-purity argon gas at 0.4 Mpa to 0.6 Mpa. Then, heat the nozzle of the glass tube 3 with acetylene to seal the tube, avoiding oxidation reactions during the interfacial reaction between the solubility measurement sample 1 and the high-purity carbon block 2;

[0050] S45. Divide the N glass tubes 3 filled with the high-purity carbon block 2 and the solubility measurement sample 1 into M groups, and prepare M muffle furnaces. Each group of glass tubes 3 corresponds to a muffle furnace. Vertically place the glass tubes 3 in each group into the corresponding muffle furnace to ensure that the solubility measurement sample 1 in the glass tube 3 can be in full contact with the high-purity carbon blocks 2 on the upper and lower sides; Set a heating temperature for each group of muffle furnaces, and the heating temperatures of the M groups of glass tubes 3 in this step correspond one-to-one and are the same as the melting temperatures of the M groups of alloy samples in S1. That is to say, in this embodiment, at least 3 sets of maximum C solubility Cs values at different melting temperatures need to be obtained, and each maximum C solubility Cs corresponds to a set of experimental groups in S1; In addition, each group of glass tubes 3 needs to be kept warm in addition to being heated at their respective corresponding heating temperatures, and the holding time of each glass tube 3 in each group of glass tubes 3 increases in a geometric sequence with a common ratio of 2, with the starting holding temperature being 0.5 h, that is, the holding time of the first glass tube 3 in each group is 0.5 h, the holding time of the second glass tube 3 is 1 h, the holding time of the third glass tube 3 is 2 h, the holding time of the fourth glass tube 3 is 4 h..., and keep warm according to such a rule to cause different degrees of interfacial reactions between the solubility measurement sample 1 and the high-purity carbon block 2;

[0051] S46. When each glass tube 3 reaches the holding time, take out the glass tube 3 from the muffle furnace, break the glass tube 3 and take out the solubility measurement sample 1 dissolved with C, and measure the carbon content of the solubility measurement sample 1 with a carbon-sulfur analyzer. After measuring the carbon contents of all the solubility measurement samples 1, the maximum C solubility Cs of the interfacial reaction at different heating temperatures can be obtained;

[0052] S5. Obtain the rate constant k at different melting temperatures based on the C content C(t) of each amorphous alloy sample and the maximum C solubility Cs:

[0053]

[0054] where Co is the initial C solubility of the alloy sample (which can be regarded as 0), and t is the melting time;

[0055] S6. Based on the rate constant k obtained in S5, the C increment of the alloy sample melted using a high-purity graphite crucible at any moment can be obtained.

[0056] In this embodiment, a high-purity graphite crucible equipped with medium-frequency induction melting technology is used to prepare amorphous alloys. During the melting process, small atomic C in the high-purity graphite crucible can be forced to diffuse into the interstitial spaces of the amorphous alloy atoms, thereby increasing the shear band free volume and the degree of amorphousness. At the same time, at least three test groups are adopted in this embodiment to prove that based on the above method for improving the strong plasticity of amorphous alloys, the C increment of the amorphous alloy at a certain melting temperature and any melting time during the melting of amorphous alloys using a high-purity graphite crucible can be determined, so that amorphous alloy samples with different degrees of small atomic C increments can be prepared. The method for improving the strong plasticity of amorphous alloys in this embodiment is simple and can be achieved only by using a high-purity graphite crucible equipped with medium-frequency induction melting technology. The overall technology is stable, with low cost and low energy consumption, and can effectively improve the strong plasticity of amorphous alloys. In addition, the method for improving the strong plasticity of amorphous alloys in this embodiment is also applicable to alloys with different compositions and metal ratios, and is also applicable to the diffusion of different elements. For example, a quartz crucible is used to melt amorphous alloys to force O elements to diffuse into the interstitial spaces of the amorphous alloys to solid-solution strengthen or form crystal phases to strengthen the amorphous alloys, etc.

[0057] Example 1:

[0058] S1. Weigh each metal raw material according to the target atomic percentages of Zr 52.5%, Cu 17.9%, Ni 14.6%, Al 10%, and Ti 5%. All metal raw materials are high-purity raw materials. Mix the metal raw materials evenly to obtain alloy samples. Weigh 50 g of alloy samples, a total of 9 portions. Divide the 9 portions of alloy samples into 3 test groups evenly. Place the 3 groups of alloy samples in a medium-frequency induction furnace equipped with a high-purity graphite crucible. Before induction melting each portion of the alloy sample, evacuate the high-purity graphite crucible and fill it with high-purity argon gas at 0.5 MPa to avoid oxidation reactions during the melting process of the alloy samples;

[0059] At the beginning of melting, three melting temperatures were set for the three experimental groups, which were 1150K, 1250K, and 1350K respectively. One of the experimental groups melted at 1150K, and the three alloy samples in this group were melted at 5min, 25min, and 45min respectively. One experimental group melted at 1250K, and the three alloy samples in this group were melted at 5min, 25min, and 45min respectively. The other experimental group melted at 1350K, and the three alloy samples in this group were also melted at 5min, 25min, and 45min respectively. In this way, the diffusion amount of small atom C in the obtained amorphous alloy at the melting temperatures of 1150K, 1250K, and 1350K and the melting times of 5min, 25min, and 45min can be determined. The melting time of the alloy sample is recorded as the zero point of timing when the alloy sample is completely melted; during the process of melting the alloy using a high-purity graphite crucible, it is possible to force the small atom C to diffuse and dissolve into the interstitial space of the amorphous alloy, thereby increasing the free volume of the shear band and increasing the degree of amorphousness;

[0060] After each alloy sample is melted, the molten alloy is poured into a high-purity copper mold for cooling to obtain an amorphous alloy sample with C element diffused. After all alloy samples are melted and cooled, a total of 9 amorphous alloy samples with C element diffused are obtained;

[0061] S2. The C content C(t) of the 9 amorphous alloy samples is obtained by a carbon-sulfur analyzer. The C content C(t) of each amorphous alloy sample is shown in Table 1:

[0062] Table 1: Carbon content of amorphous alloy samples prepared by using a high-purity graphite crucible equipped with intermediate-frequency induction melting technology at three melting temperatures and melting times

[0063]

[0064] It can be seen from Table 1 that as the melting temperature and melting time increase, the C content C(t) of the amorphous alloy samples also gradually increases.

[0065] S3. Since the weight of each alloy sample is 50g, when the 50g alloy sample is placed in the crucible for melting, the alloy sample melts, and the density of each metal is determined. Therefore, based on the weight and density of the alloy sample, the volume V of each alloy sample can be calculated. V = 7.58e-6m 3 , based on the shape and size of the inner surface of the high-purity graphite crucible, the contact area S between the alloy sample and the inner surface of the high-purity graphite crucible is determined. The high-purity graphite crucible in this embodiment uses a frustum-shaped crucible cavity, as Figure 2As shown, the inner diameter of the crucible bottom is 21 mm, the inner diameter at the crucible mouth is 25 mm, and the height of the inner cavity of the crucible is 45 mm. Based on the volume V of the alloy sample, the contact area S between the alloy sample and the inner surface of the high-purity graphite crucible is calculated to be 1.73e-3 m 2 .

[0066] S4. Directly adopt the method of diffusing small-sized C atoms into the amorphous alloy to obtain the maximum C solubility Cs of the interfacial reaction of the alloy sample with the same metal composition and ratio as in S1 at the above three different melting temperatures of 1150K, 1250K, and 1350K. The relationship among the C solubility, melting time, and melting temperature in the alloy sample is obtained via the maximum C solubility Cs. The steps for obtaining the maximum C solubility Cs are as follows:

[0067] S41. Weigh each metal raw material according to the target atomic percentages of Zr 52.5%, Cu 17.9%, Ni 14.6%, Al 10%, and Ti 5%, mix them evenly to obtain alloy sample two, and alloy sample two is melted by arc melting to obtain a button ingot sample;

[0068] S42. Remelt the button ingot sample obtained in S41 in a vacuum arc furnace, and use the suction casting method to suction-cast it into a rectangular high-purity copper mold with a width and height of 3 mm to cool and solidify. Take out the solidified sample from the high-purity copper mold, and use a diamond slow saw to cut the solidified sample to obtain 27 solubility measurement samples 1 with a length, width, and height of 3 mm;

[0069] S43. Prepare 27 glass tubes 3 with an inner diameter of 6 mm and 54 high-purity carbon blocks 2 with a diameter of 5.9 mm and a height of 3 mm. Divide the 54 high-purity carbon blocks 2 into 27 groups, with each group of high-purity carbon blocks 2 corresponding to a solubility measurement sample 1 and a glass tube 3. In turn, place one of the high-purity carbon blocks 2, the solubility measurement sample 1, and the other high-purity carbon block 2 in each group into the corresponding glass tube 3, where the high-purity carbon block 2 directly provides small-sized C atoms for the solubility measurement sample 1;

[0070] S44. Vacuum the glass tube 3 filled with the high-purity carbon block 2 and the solubility measurement sample 1, then fill it with high-purity argon gas at 0.5 Mpa, and then heat the mouth of the glass tube 3 with acetylene to seal the tube, avoiding oxidation reactions during the interfacial reaction between the solubility measurement sample 1 and the high-purity carbon block 2;

[0071] S45. Divide the 27 glass tubes 3 containing high-purity carbon blocks 2 and solubility measurement samples 1 into 3 groups, and prepare 3 muffle furnaces. Each group of glass tubes 3 corresponds to one muffle furnace. Vertically place the glass tubes 3 in each group into the corresponding muffle furnace to ensure that the solubility measurement samples 1 in the glass tubes 3 can be in full contact with the high-purity carbon blocks 2 on the upper and lower sides. One group of muffle furnaces heats the glass tubes 3 at a temperature of 1150K, and the heating durations of the 9 glass tubes 3 in this group are 0.5h, 1h, 2h, 4h, 8h, 16h, 32h, 64h, and 128h respectively. One group of muffle furnaces heats the glass tubes 3 at a temperature of 1250K, and the heating durations of the 9 glass tubes 3 in this group are 0.5h, 1h, 2h, 4h, 8h, 16h, 32h, 64h, and 128h respectively. Another group of muffle furnaces heats the glass tubes 3 at a temperature of 1350K, and the heating durations of the 9 glass tubes 3 in this group are 0.5h, 1h, 2h, 4h, 8h, 16h, 32h, 64h, and 128h respectively, so as to cause different degrees of interfacial reactions between the solubility measurement samples 1 and the high-purity carbon blocks 2 at different heating temperatures and heating times.

[0072] S46. When each glass tube 3 reaches the heat preservation time, take out this glass tube 3 from the muffle furnace, break the glass tube 3 and take out the solubility measurement sample 1 dissolved with C, and measure the carbon content of this solubility measurement sample 1 through a carbon-sulfur analyzer. After measuring the carbon contents of all solubility measurement samples 1, the maximum C solubility Cs of the interfacial reaction at three heating temperatures of 1150K, 1250K, and 1350K can be obtained. Among them, the maximum C solubility Cs at the heating temperature of 1150K is 1.24wt.%, the maximum C solubility Cs at the heating temperature of 1250K is 1.83wt.%, and the maximum C solubility Cs at the heating temperature of 1350K is 2.78wt.%.

[0073] S5. Use the maximum C solubility Cs at the heating temperature of 1150K obtained in step S46, and C(t) at the melting temperature of 1150K and melting times of 5min, 25min, and 45min obtained in step S2, and based on the kinetic formula Calculate respectively at melting times of 5min, 25min, and 45min Establish A coordinate system of and t, and substitute the above three melting times Into Figure 4 Of the coordinate system to obtain at the melting temperature of 1150K The value of , so as to obtain the rate constant k at the melting temperature of 1150K; by using the same calculation method, the rate constants k at the melting temperatures of 1250K and 1350K are obtained respectively, and then the C increment C(t) of the alloy sample melted by the high-purity graphite crucible at any time can be obtained.

[0074] Uniaxial compression tests and nanoindentation tests were carried out on the amorphous alloy samples prepared by using the high-purity graphite crucible equipped with medium-frequency induction melting technology to verify whether the in-situ diffusion of C elements through the high-purity graphite crucible can effectively improve the strength and plasticity of the amorphous alloy and obtain the optimal C content. The specific verification process is as follows:

[0075] Uniaxial compression test: Select 5 amorphous alloy samples in S1 as the specimens for the uniaxial compression test. Machine-process these 5 specimens to obtain compression specimens with a diameter of 4 mm and a height of 6 mm. These 5 compression specimens are respectively designated as specimen 1 (1150K, 25 min), specimen 2 (1250K, 25 min), specimen 3 (1350K, 5 min), specimen 4 (1350K, 25 min) and specimen 5 (1350K, 45 min). Use a universal compressor to axially compress these 5 compression specimens, and the compression rate is 0.01 s -1 , and finally obtain the compressive strength and plasticity of these 5 compression specimens. The test results are as Figure 4 shown. In the figure, the numerical values of the pink curve represent the plasticity of these 5 compression specimens, and the numerical values of the purple curve represent the compressive strength of these 5 compression specimens. It can be seen from this figure that specimen 4 (1350K, 25 min) has the strongest compressive strength and plasticity and the best mechanical properties, proving that the in-situ diffusion of C elements through the high-purity graphite crucible can effectively improve the strength and plasticity of the amorphous alloy.

[0076] Nanoindentation test: Select 5 amorphous alloy samples in S1 as the specimens for the nanoindentation test. Machine-process these 5 specimens to obtain indentation specimens with a diameter of 4 mm and a height of 3 mm. These 5 indentation specimens are respectively designated as specimen 1 (1150K, 25 min), specimen 2 (1250K, 25 min), specimen 3 (1350K, 5 min), specimen 4 (1350K, 25 min) and specimen 5 (1350K, 45 min). Before the test, polish these 5 indentation specimens first, and then randomly select 4 4×4 lattices on each indentation specimen, with a distance of 10 um between each point. That is to say, each indentation specimen has 64 pressurization points. Use a Berkovich diamond indenter with a tip diameter of 10 nm to pressurize the pressurization points of each indentation specimen, with a loading rate of 1 mN / s, a maximum load of 15 mN, and a recording frequency of 300 Hz. Then through

[0077]

[0078] where: f is the cumulative distribution function of the first yield in the nanoindentation experiment, kT is the thermal energy, dτ / dt is the loading rate of the nanoindentation test, τ is the maximum shear stress at the first yield in the nanoindentation experiment, and V* is the shear band free volume of the calculated amorphous alloy. Therefore, by taking ln[ln(1 - f) -1 as the ordinate and τ as the abscissa, a linear fit of the coordinate points can obtain the slope to obtain the shear band free volume V*.

[0079] Calculate V* / kT of 5 indentation specimens respectively according to the above method. The specific calculation results are shown in Table 2:

[0080] Table 2: V* / kT values of the 5 obtained indentation specimens

[0081]

[0082]

[0083] Combined with Table 1 and Figure 5 it can be seen that the shear band free volume of the indentation specimens changes with the change of carbon content C(t), and the shear band free volume of Specimen 4 (1350K, 25min) is the largest.

[0084] Through the above two experiments, it can be proved that the shear band free volume of Specimen 4 (1350K, 25min) is the largest, and it has the maximum compressive strength and plasticity, proving that the introduction of carbon atoms improves the strong plasticity of the degree of amorphization and increases the shear band free volume. For this alloy composition, the most suitable carbon content is 1170 ppm. After obtaining the optimal carbon content, the holding time required at a temperature suitable for the production situation can be obtained according to the formula in Step S5.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for improving the strength and plasticity of amorphous alloys, characterized in that, The improvement process is as follows: S1. Weigh each metal raw material according to the target atomic percentage, mix them evenly to obtain an alloy sample, divide the alloy sample into multiple portions, and further divide the multiple alloy samples into M groups. The M groups of alloy samples are respectively placed in an intermediate frequency induction furnace equipped with a high-purity graphite crucible. Before induction melting each portion of the alloy sample, first evacuate the high-purity graphite crucible and fill it with high-purity argon. At the start of melting, set different melting temperatures for each group of alloy samples, set different melting times for different alloy samples in each group, and record the moment when the alloy sample is completely melted as the timing zero point. After each portion of the alloy sample is melted, pour the molten alloy at different melting temperatures and melting times into a cooling mold for cooling, and sequentially obtain multiple amorphous alloy samples diffused with C element; S2. Obtain the C content C(t) of each amorphous alloy sample in S1; S3. Determine the volume V of any one alloy sample in S1, and deduce the contact area S between this alloy sample and the inner surface of the high-purity graphite crucible; In S3, the volume V of the alloy sample is determined based on the weight and density of the alloy sample, and the contact area S between the alloy sample and the inner surface of the high-purity graphite crucible is determined based on the shape and size of the inner surface of the high-purity graphite crucible; S4. Obtain the maximum C solubility Cs of the interfacial reaction of the alloy sample at the above different melting temperatures; The maximum C solubility Cs in S4 is obtained through the following steps: S41. Arc melt an alloy sample with the same metal composition and ratio as in S1 to obtain a button ingot sample; S42. Remelt the button ingot sample obtained in S41 in a vacuum arc furnace, and use the suction casting method to suction cast it into a high-purity copper mold for cooling and shaping. After machining, obtain N solubility measurement samples with the same volume; S43. Prepare N glass tubes and 2N high-purity carbon blocks. Divide the 2N high-purity carbon blocks into N groups. Each group of high-purity carbon blocks corresponds to a solubility measurement sample and a glass tube. Sequentially place one of the high-purity carbon blocks, the solubility measurement sample, and the other high-purity carbon block in each group into the corresponding glass tube; S44. Evacuate the glass tube filled with high-purity carbon blocks and solubility measurement samples, and then fill it with high-purity argon and seal the tube; S45. Divide the N glass tubes in S44 into M groups. The M groups of glass tubes are respectively placed in a muffle furnace, and heated and insulated at different heating temperatures. The insulation time of the glass tubes in each group is different, so that the solubility measurement samples react with the high-purity graphite blocks to different degrees. Among them, the heating temperature of each group of glass tubes corresponds one-to-one with the melting temperature of each group of alloy samples in S1; S46. When each glass tube reaches the insulation moment, take out the glass tube from the muffle furnace, break the glass tube and take out the solubility measurement sample dissolved with C element, and measure the carbon content of the solubility measurement sample with a carbon-sulfur analyzer. After measuring the carbon content of all solubility measurement samples, the maximum C solubility Cs of the interfacial reaction at different melting temperatures can be obtained; S5. Obtain the rate constant k at different melting temperatures based on the C content C(t) of each amorphous alloy sample and the maximum C solubility Cs; Where Co is the initial C solubility of the alloy sample, and t is the melting time; S6. Based on the rate constant k obtained in S5, the C increment of the alloy sample melted using the high-purity graphite crucible at any time can be obtained.

2. The method for improving the strength and plasticity of an amorphous alloy according to claim 1, wherein The pressure of the high-purity argon gas filled in the high-purity graphite crucible in S1 is 0.4 MPa to 0.6 MPa.

3. A method for improving the strength and plasticity of amorphous alloys according to claim 1, characterized in that, The high-purity graphite crucible in S1 is equipped with a boron nitride ceramic sleeve on the outside to protect the inductor.

4. A method for improving the strength and plasticity of amorphous alloys according to claim 1, characterized in that, The cooling mold in S1 is a high-purity copper mold.

5. A method for improving the strength and plasticity of an amorphous alloy according to claim 1, characterized in that, In S2, the C content C(t) of each amorphous alloy sample is obtained by a carbon-sulfur analyzer.

6. The method for improving the strength and plasticity of an amorphous alloy according to claim 1, wherein The pressure of the high-purity argon gas in S44 is 0.4 to 0.6 MPa.

7. A method for improving the strength and plasticity of amorphous alloys according to claim 1, characterized in that, The glass tube in S45 is vertically placed into the muffle furnace to ensure that the high-purity carbon block and the solubility measurement sample can be in full contact.

8. A method for improving the strength and plasticity of amorphous alloys according to claim 1, characterized in that, The holding time of each glass tube in each group of glass tubes in S44 increases in a geometric progression with a common ratio of 2, and the starting holding temperature is 0.5 h.

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