A method for designing the macroscopic morphology of molten metal

Abstract

The present invention provides a method for designing the macroscopic morphology of a metal melt, the method comprising: placing a metal sample in a high-magnetic field material processing device and applying a target high-magnetic field so that the sample is in an environment of a specific high-magnetic field strength H and a gradient magnetic field dH / dZ; performing multiple melt superheating and supercooling cycles to ensure that the supercooling degree ΔT of the sample remains unchanged before and after the magnetic field is applied; recording the temperature-time curve of the sample in the last heating and cooling stages and the change data of the mass m0 of the sample in the solidified state under the magnetic field; and obtaining the starting temperature T of the peak generated in the cooling stage curve from the temperature-time curve. N , calculate the first constant paramagnetic-ferromagnetic Curie transition temperature θ of the melt and the Curie constant C of the sample; establish a functional relationship between the dependent variable corresponding to the macroscopic morphology of the melt and the second constant related to ΔT, H, dH / dZ, θ and the sample, where C is used to calculate the second constant; and judge the macroscopic morphology of the melt based on the dependent variable.

Description

Technical Field

[0001] The invention relates to the technical field of material melt processing, and in particular to a method for designing the macroscopic morphology of metal melt. Background Art

[0002] During the forming process, metals and their products undergo at least one solidification process, from liquid to solid. Above the melting point, metals are in a molten state, and their macroscopic shape is influenced by a variety of factors. According to the liquid mean field theory model, under the influence of external forces, the melt tends to spheroidize, reducing its surface area to lower its surface energy. Simultaneously, under the influence of gravity and external fields, it tends to become more locally sharp. Under the competing effects of these two forces, the melt ultimately exhibits a variety of macroscopic morphologies, exhibiting unstable characteristics. Macroscopic morphology has a significant impact on the distribution of microstructures and ultimate service performance. Continuously optimizing the microstructure and properties of metal materials is a hot topic in academia and industry. Therefore, starting from the perspective of melt macroscopic morphology, it is necessary to actively predict and screen the melt's macroscopic morphology by controlling melt processing parameters. Furthermore, by drawing on melt macroscopic morphology processing technology and applying it to surface morphology modification in hydrogels, coatings, and other applications, products with diverse surface patterns can be produced, promoting the development of CMF design for products from the perspectives of appearance, artistry, and practicality.

[0003] In recent research on melt morphology instabilities, some researchers have successfully produced a variety of Co macrostructures in pure Co metal by adjusting the external magnetic field intensity H, magnetic field gradient dH / dZ, and supercooling ΔT during the supercooling solidification stage of the melt, such as lotus-shaped, teardrop-shaped, and spherical. Notably, under conditions of a strong 12T magnetic field and a near-zero gradient, a melt sample with a ΔT between 320K and 330K splits in two along its central axis during solidification, forming two more elongated, sharper teardrop structures. This demonstrates that various macromorphological controls can be achieved for Co melts under different magnetic field conditions and supercooling conditions. However, it is clear that Co metal has a relatively high Curie temperature of approximately 1393K, resulting in a strong magnetic property during supercooling solidification (nucleation temperature below the Curie temperature), making it more susceptible to manipulation in a magnetic field. However, for more metals and their alloys, which have lower Curie temperatures and often solidify well above the Curie temperature, exhibiting weak magnetism, it remains unclear whether magnetic fields can still exert a regulatory effect. In addition, the rules for regulating the macroscopic morphology of the melt by the combined effects of magnetic field intensity, magnetic field gradient, and supercooling still need to be further quantified and standardized, and a universal criterion for actively designing melts with different morphologies by controlling parameters should be proposed. Summary of the Invention

[0004] This paper proposes a method for designing the macromorphology of metal melts. Metals and alloys are subjected to a superheating and cooling cycle, with controlled heating and cooling rates, heating temperature, and holding time to achieve a range of supercooling degrees (ΔT). A high magnetic field is then generated using a liquid helium-free superconducting magnet system, with the sample position aligned with a specific gradient magnetic field. By regulating the intensity of the high and gradient magnetic fields, the melt is ultimately cooled and solidified to form a specific macromorphology.

[0005] Specifically, the present invention provides a method for designing the macroscopic morphology of a metal melt, comprising the following steps:

[0006] Step 1: Place the metal sample in a high-magnetic field material processing device and apply a target high-magnetic field so that the sample is in an environment with a specific high-magnetic field strength H and a gradient magnetic field dH / dZ, with the direction of the gradient magnetic field being the same as the direction of gravity;

[0007] Step 2: Perform multiple melt superheating and supercooling cycles to ensure that the supercooling degree ΔT of the sample remains unchanged before and after the magnetic field is applied. Record the temperature T-time t curve of the sample in the last heating and cooling stage and the change data of the mass m0 of the sample in the solidified state under the magnetic field. Obtain the starting temperature T of the peak of the cooling stage curve from the temperature T-time t curve. N , after the cycle is completed, remove the sample;

[0008] Step 3: Based on the temperature T in step 2 and the mass m0 of the solidified sample under the magnetic field, calculate the first constant paramagnetic-ferromagnetic Curie transition temperature θ of the melt and the Curie constant C of the sample;

[0009] Step 4: Establishing a functional relationship between the dependent variable corresponding to the melt macromorphology and the supercooling ΔT, the strong magnetic field intensity H, the strong magnetic field gradient dH / dZ, the paramagnetic-ferromagnetic Curie transition temperature θ and a second constant related to the sample, wherein the Curie constant C is used to calculate the second constant;

[0010] Step 5: Determine the macroscopic morphology of the melt based on the dependent variable.

[0011] As a further illustration of the present invention, before performing step 1, the method further includes: placing the metal sample in a strong magnetic field material processing device, heating it to a maximum heating temperature at a certain rate, keeping it warm for a certain time so that the melt is fully uniform, and then cooling it at the same rate, repeating the above heating and cooling processes until the supercooling ΔT obtained by multiple consecutive measurements is stable.

[0012] As a further illustration of the present invention, the supercooling ΔT needs to be stable after at least 5 consecutive measurements.

[0013] As a further illustration of the present invention, in step 2, when recording the temperature-time curves of the melt heating and cooling stages and the change data of the mass m0 of the sample in the solidified state under the magnetic field, a balance system that is compatible with the strong magnetic field material processing device is used for recording.

[0014] As a further illustration of the present invention, in step 3, the calculation process of the paramagnetic-ferromagnetic Curie transition temperature θ of the melt and the Curie constant C of the sample specifically includes:

[0015] Using the Faraday balance principle, the m0 data is converted into the sample magnetic susceptibility χ. The specific calculation formula is as follows:

[0016]

[0017] Where g is the gravity of the sample under the magnetic field when solidifying, m0 is the balance reading under the magnetic field when solidifying, that is, the mass of the sample in the solidified state under the magnetic field, m is the balance reading in the absence of a magnetic field, that is, the mass of the sample, dH / dZ is the gradient magnetic field value of the sample at the corresponding position in the device, and H is the target magnetic field strength applied;

[0018] With temperature T as the abscissa and the inverse of magnetic susceptibility 1 / χ as the ordinate, a graph is drawn. 1 / χ and temperature T satisfy the Curie-Weiss relationship as follows:

[0019]

[0020] Where C is the Curie constant of the sample, θ is the paramagnetic-ferromagnetic Curie transition temperature of the melt;

[0021] Further linear fitting is performed on the drawn curve, and the slope of the curve k = 1 / C, and the intercept with the temperature axis b = -θ / C, then C and θ can be calculated using the following formula:

[0022]

[0023] As a further illustration of the present invention, the functional relationship established in step 4 is specifically the following formulas (4) to (7):

[0024] y1=H 4 (4)

[0025]

[0026] y3=H (6)

[0027]

[0028] Where y1, y2, y3 and y4 are four dependent variables corresponding to the macroscopic morphology of the melt, θ is obtained by formula (3), P1, P2, P3 and P4 are the second constants related to the material, and are calculated by formulas (8) to (11) respectively:

[0029]

[0030]

[0031]

[0032]

[0033] Where C is obtained by formula (3), α is the dimensionless structure factor, ΔHf is the melting enthalpy of the substance (J / mol), and T m is the melting point of the substance (K), μ0 is the vacuum permeability, and 4π×10 -7 N / A 2 , N A is Avogadro's constant, which is 6.02×10 23 / mol,V m is the molar volume of the substance (m 3 / mol), Δρ m is the difference between the density of the solid and liquid phases.

[0034] As a further illustration of the present invention, in step 5, judging the macroscopic morphology of the melt according to the dependent variable specifically includes:

[0035] Determine the size of y1 and y2. When y1 is smaller than y2, the melt is a spherical melt.

[0036] When y1 is greater than or equal to y2, the size of y3 and y4 is determined. When y3 is less than y4, the melt is a water drop-shaped melt. When y3 is greater than or equal to y4, the melt is a lotus-shaped melt.

[0037] Compared with the prior art, the present invention has the following beneficial technical effects:

[0038] The influence of melt macromorphology changes on microstructure and performance is often overlooked by researchers. Macromorphology changes have important research value in terms of artistic appreciation and surface functionality (roughness, etc.). The method provided by the present invention can directly quantify the corresponding relationship between melt processing parameters and macromorphology, and the melt composition is not limited to ferromagnetic materials such as Co, etc., covering a wider range and also for weakly magnetic materials. The operation method is simple, and data integration and calculation are convenient. It can achieve the goal of actively designing and regulating the melt macromorphology, thereby guiding the solidification organization and performance design more intuitively and scientifically.

[0039] Other features and advantages of this technical solution will be described in the subsequent description, and in part will become apparent from the description, or understood by practicing this technical solution. The objectives and other advantages of this technical solution can be achieved and obtained through the structures specifically pointed out in the written description and the accompanying drawings.

[0040] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present technical solution and constitute a part of the specification. Together with the embodiments of the present technical solution, they are used to explain the present technical solution and do not constitute a limitation of the present technical solution. In the accompanying drawings:

[0042] Figure 1 It is a flow chart of melt macromorphology criteria.

[0043] Figure 2 The Co prepared in Example 1 of the present invention 80 B 20 Alloy macromorphology and supercooling curve.

[0044] Figure 3 The Co prepared in Example 2 of the present invention 80 B 20 Alloy macromorphology and supercooling curve.

[0045] Figure 4 The Co prepared in Example 3 of the present invention 80 B 20 Alloy macromorphology and supercooling curve.

[0046] Figure 5 The Co prepared in Example 4 of the present invention 80 B 20 Alloy macromorphology and supercooling curve.

[0047] Figure 6 The Co prepared in Example 5 of the present invention 81.5 B 18.5 Alloy macromorphology and supercooling curve.

[0048] Figure 7 The Co prepared in Example 6 of the present invention 81.5 B 18.5 Alloy macromorphology and supercooling curve.

[0049] Figure 8 The Co prepared in Example 7 of the present invention 81.5 B 18.5 Alloy macromorphology and supercooling curve.

[0050] Figure 9 The Co prepared in Example 8 of the present invention 83 B 17 Alloy macromorphology and supercooling curve.

[0051] Figure 10 The Co prepared in Example 9 of the present invention 83 B 17 Alloy macromorphology and supercooling curve.

[0052] Figure 11 It is a two-dimensional coordinate scatter diagram of the morphology judgment of the alloys corresponding to Examples 1 to 9 of the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0054] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal manner unless otherwise explicitly defined herein.

[0055] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0056] The present invention proposes a method for designing the macroscopic morphology of a metal melt. The metal and alloy materials are subjected to a superheating and supercooling cycle treatment method. The heating and cooling rates, heating temperature, and holding time are regulated to obtain a series of supercooling degrees ΔT. Subsequently, a liquid helium-free superconducting magnet system is used to excite a strong magnetic field. The sample position corresponds to a specific gradient magnetic field. By regulating the strength of the strong magnetic field and the gradient magnetic field, the melt is finally cooled and solidified to form a specific macroscopic morphology of the melt.

[0057] like Figure 1As shown, the present invention provides a method for designing the macroscopic morphology of a metal melt, comprising the following steps:

[0058] Step 1: Place the metal sample in a high-magnetic field material processing device and apply a target high-magnetic field so that the sample is in an environment with a specific high-magnetic field strength H and a gradient magnetic field dH / dZ, where the direction of the gradient magnetic field is the same as the direction of gravity.

[0059] Step 2: Perform multiple melt superheating and supercooling cycles to ensure that the supercooling degree ΔT of the sample remains unchanged before and after the magnetic field is applied. Record the temperature-time t curve of the sample in the last heating and cooling stage and the change data of the mass m0 of the sample in the solidified state under the magnetic field. Obtain the starting temperature T of the peak of the cooling stage curve from the temperature T-time t curve. N , remove the sample after the cycle is completed.

[0060] In addition, for some types of samples, the supercooling degree may change before and after the magnetic field is applied. Therefore, before proceeding to step 1, the following supercooling degree ΔT stabilization process is also included:

[0061] The metal sample is placed in a strong magnetic field material processing device, heated to the maximum heating temperature at a certain rate, kept at this temperature for a certain period of time to allow the melt to be fully uniform, and then cooled at the same rate. The above heating and cooling processes are repeated until the supercooling ΔT obtained by multiple consecutive measurements is stable.

[0062] The process of heating up and cooling down may be repeated 8-10 times, until the supercooling ΔT obtained by continuous measurement for more than 5 times is stable (with an average error of less than 2%).

[0063] The sample is subjected to different treatment methods, such as changing the heating temperature, holding time, and heating / cooling rate of the melt, and is cycled multiple times until the measured ΔT data does not fluctuate and the melt reaches a stable state.

[0064] The above-mentioned undercooling ΔT stabilization process can ensure that the above-mentioned step 2 maintains the undercooling degree consistent with that before the magnetic field is applied. However, for some metal samples, since the undercooling degree before and after the magnetic field is applied does not change much, the above-mentioned undercooling ΔT stabilization process before the magnetic field application can be omitted.

[0065] Specifically, the operation method to ensure that ΔT remains unchanged in step 2 is: when ΔT increases, the maximum heating temperature is lowered and the holding time is shortened; when ΔT decreases, the maximum heating temperature is increased and the holding time is increased.

[0066] Specifically, a balance system matched with a strong magnetic field material processing device is used to record the temperature T-time t curves of the melt heating and cooling stages and the change data of the mass m0 of the sample in the solidified state under the magnetic field.

[0067] Step 3: Based on the temperature T in step 2 and the mass m0 of the sample in the solidified state under the magnetic field, calculate the first constant paramagnetic-ferromagnetic Curie transition temperature θ of the melt and the Curie constant C of the sample.

[0068] The calculation process of the paramagnetic-ferromagnetic Curie transition temperature θ of the melt and the Curie constant C of the sample specifically includes:

[0069] Using the Faraday balance principle, the m0 data is converted into the sample magnetic susceptibility χ, which does not change with the external field H. The specific calculation formula is as follows:

[0070]

[0071] Where g is the gravity of the sample under the magnetic field when solidifying, m0 is the balance reading under the magnetic field when solidifying, that is, the mass of the sample in the solidified state under the magnetic field, m is the balance reading in the absence of a magnetic field, that is, the mass of the sample, dH / dZ is the gradient magnetic field value of the sample at the corresponding position in the device, and H is the target magnetic field strength applied;

[0072] With temperature T as the abscissa and the inverse of magnetic susceptibility 1 / χ as the ordinate, a graph is drawn. 1 / χ and temperature T satisfy the Curie-Weiss relationship as follows:

[0073]

[0074] Where C is the Curie constant of the sample, θ is the paramagnetic-ferromagnetic Curie transition temperature of the melt;

[0075] Further linear fitting is performed on the drawn curve, and the slope of the curve k = 1 / C, and the intercept with the temperature axis b = -θ / C, then C and θ can be calculated using the following formula:

[0076]

[0077] Step 4: Establish a functional relationship between the dependent variable corresponding to the macroscopic morphology of the melt and the supercooling ΔT, the strong magnetic field intensity H, the strong magnetic field gradient dH / dZ, the paramagnetic-ferromagnetic Curie transition temperature θ and the second constant related to the sample, where the Curie constant C is used to calculate the second constant.

[0078] The functional relationship established in step 4 is specifically the following formulas (4) to (7):

[0079] y1=H 4 (4)

[0080]

[0081] y3=H (6)

[0082]

[0083] Where y1, y2, y3 and y4 are four dependent variables corresponding to the macroscopic morphology of the melt, θ is obtained by formula (3), P1, P2, P3 and P4 are the second constants related to the material, and are calculated by formulas (8) to (11) respectively:

[0084]

[0085]

[0086]

[0087]

[0088] Where C is obtained by formula (3), α is the dimensionless structure factor, ΔHf is the melting enthalpy of the substance (J / mol), and T m is the melting point of the substance (K), μ0 is the vacuum permeability, and 4π×10 -7 N / A 2 , N A is Avogadro's constant, which is 6.02×10 23 / mol,V m is the molar volume of the substance (m 3 / mol), Δρ m The difference between the solid and liquid phase densities. The above parameters can be found in physical and chemical handbooks for specific sample materials.

[0089] Step 5: Determine the macroscopic morphology of the melt based on the dependent variable.

[0090] The specific judgment process includes: judging the size of y1 and y2. When y1 is less than y2, the melt is a spherical melt; when y1 is greater than or equal to y2, then continue to judge the size of y3 and y4. When y3 is less than y4, the melt is a water drop-shaped melt; when y3 is greater than or equal to y4, the melt is a lotus-shaped melt.

[0091] The rationality of the design method of the metal melt macromorphology provided by the present invention is verified below with reference to specific embodiments.

[0092] Since the supercooling of the samples used in the following examples did not change much before and after the magnetic field was applied, the supercooling ΔT stabilization process before the magnetic field was applied was ignored. The following examples are used to verify the rationality of the design method proposed in the present invention.

[0093] Example 1:

[0094] A method for designing the macroscopic morphology of metal melts based on Co 80 B 20Taking alloy as an example, the specific expression method is:

[0095] The sample was heated from room temperature to 1400°C at a rate of 5°C / min in a static magnetic field of 3T and a gradient magnetic field of 23.235T / m. The sample was kept at this temperature for 5 minutes and then cooled at the same rate. This cycle was repeated 5 times until the obtained ΔT data did not fluctuate. The curve of T versus time t during the last heating and cooling process of the sample was recorded, as shown in Figure 2. Figure 2 As shown in a. It can be found that the melting point T L When the temperature of the sample is at a certain temperature T N The sudden rise in temperature corresponds to the nucleation and growth of the primary solid phase from the melt, that is, the beginning of the solidification process. The supercooling ΔT is defined as the melting point T of the substance. L and nucleation temperature T N In this example, ΔT is about 272°C.

[0096] After solidification, the sample was taken out and the macroscopic morphology of the sample was as follows: Figure 2 As shown in b. It can be seen that the sample has a spherical morphology as a whole and no surface instability occurs. Figure 1 The macroscopic morphology judgment process shown in the figure is shown in the figure. The y1, y2, y3 and y4 values ​​obtained by substituting various numerical values ​​are 81, 401.52, 3, 2.74×10 -5 , a coordinate system is constructed with y1-y2 as the ordinate and y3-y4 as the abscissa. It can be seen that the corresponding data points in this example are in the fourth quadrant (y1-y2<0, y3-y4>0), and the sample should have a spherical morphology, which is consistent with the experimental observation results, indicating that it is credible to use melt processing parameter data to predict the macroscopic morphology of the melt.

[0097] Example 2:

[0098] A method for designing the macroscopic morphology of metal melts based on Co 80 B 20 Taking alloy as an example, the specific expression method is:

[0099] The sample was heated from room temperature to 1175°C at a rate of 10°C / min in a static magnetic field of 5T and a gradient magnetic field of 38.725T / m. The sample was kept warm for 10 minutes and then cooled at the same rate. This cycle was repeated three times until the obtained ΔT data had a small fluctuation. The curve of T versus time t during the last heating and cooling process of the sample was recorded, as shown in Figure 2. Figure 3 As shown in a. It can be found that the melting point T L When the temperature of the sample is at a certain temperature T NThe sudden rise in temperature corresponds to the nucleation and growth of the primary solid phase from the melt, that is, the beginning of the solidification process. The supercooling ΔT is defined as the melting point T of the substance. L and nucleation temperature T N In this example, ΔT is about 179°C.

[0100] After solidification, the sample was taken out and the macroscopic morphology of the sample was as follows: Figure 3 As shown in b. It can be seen that the sample has a spherical morphology as a whole and no surface instability occurs. Figure 1 The macroscopic morphology judgment process shown in the figure is shown in the figure. The values ​​of y1, y2, y3 and y4 obtained by substituting various numerical values ​​are 625, 6472.68, 5, and 3.19×10 -5 , constructing a coordinate system with y1-y2 as the ordinate and y3-y4 as the abscissa, it can be seen that the corresponding data points in this example are in the fourth quadrant (y1-y2<0, y3-y4>0), and the sample should have a spherical morphology, which is consistent with the experimental observation results.

[0101] This shows that it is reliable to use melt processing parameter data to predict the melt macromorphology.

[0102] Example 3:

[0103] A method for designing the macroscopic morphology of metal melts based on Co 80 B 20 Taking alloy as an example, the specific expression method is:

[0104] The sample was heated from room temperature to 1380°C at a rate of 30°C / min in a static magnetic field of 20T and a gradient magnetic field of 0.00005T / m. The sample was kept at this temperature for 5 minutes and then cooled at the same rate. Only a single cycle was performed. The obtained ΔT data had some fluctuations, but the characteristic temperature value could still be determined. The curve of T versus time t during the whole process was recorded, as shown in the figure below. Figure 4 As shown in a. It can be found that the melting point T L When the temperature of the sample is at a certain temperature T N The sudden rise in temperature corresponds to the nucleation and growth of the primary solid phase from the melt, that is, the beginning of the solidification process. The supercooling ΔT is defined as the melting point T of the substance. L and nucleation temperature T N In this example, ΔT is about 139°C.

[0105] After solidification, the sample was taken out and the macroscopic morphology of the sample was as follows: Figure 4 As shown in b. It can be seen that the sample as a whole presents an elongated water drop shape, and surface instability begins to occur. Figure 1 The macroscopic morphology judgment process shown in the figure is shown in the figure. The y1, y2, y3 and y4 values ​​calculated by various numerical calculations are 1.60×104 , 5.76×10 -2 , 20, 30.36, constructing a coordinate system with y1-y2 as the ordinate and y3-y4 as the abscissa. It can be seen that the corresponding data points in this example are in the second quadrant (y1-y2>0, y3-y4<0), and the sample should have an elongated water droplet morphology, which is consistent with the experimental observation results.

[0106] This shows that it is reliable to use melt processing parameter data to predict the melt macromorphology.

[0107] Example 4:

[0108] A method for designing the macroscopic morphology of metal melts based on Co 80 B 20 Taking alloy as an example, the specific expression method is:

[0109] The sample was heated from room temperature to 1200°C at a rate of 30°C / min in a static magnetic field of 25T and a gradient magnetic field of 0.02T / m. The sample was kept at this temperature for 10 minutes and then cooled at the same rate. Only a single cycle was performed. The obtained ΔT data had some fluctuations, but the characteristic temperature value could still be determined. The curve of T versus time t during the whole process was recorded, as shown in the following example: Figure 5 As shown in a. It can be found that the melting point T L When the temperature of the sample is at a certain temperature T N The sudden rise in temperature corresponds to the nucleation and growth of the primary solid phase from the melt, that is, the beginning of the solidification process. The supercooling ΔT is defined as the melting point T of the substance. L and nucleation temperature T N In this example, ΔT is about 112°C.

[0110] After solidification, the sample was taken out and the macroscopic morphology of the sample was as follows: Figure 5 As shown in b. It can be seen that the sample as a whole presents an elongated morphology, and the surface produces an uneven lotus peak structure, that is, the melt has obvious surface instability. Figure 1 The macroscopic morphology judgment process shown in the figure is shown in the figure. The values ​​of y1, y2, y3 and y4 obtained by substituting various numerical values ​​are 39.06×10 4 , 38.40, 25, 8.58×10 -2 , constructing a coordinate system with y1-y2 as the ordinate and y3-y4 as the abscissa, it can be seen that the corresponding data points in this example are in the first quadrant (y1-y2>0, y3-y4>0), and the sample should present a lotus-shaped elongated morphology, which is consistent with the experimental observation results.

[0111] This shows that it is reliable to use melt processing parameter data to predict the melt macromorphology.

[0112] Example 5:

[0113] A method for designing the macroscopic morphology of metal melts based on Co 81.5 B 18.5 Taking alloy as an example, the specific expression method is:

[0114] The sample was heated from room temperature to 1200°C at a rate of 10°C / min in a static magnetic field of 1.56T and a gradient magnetic field of 23.235T / m. It was then immediately cooled at the same rate. This cycle was repeated twice until the obtained ΔT data did not fluctuate. The curve of T versus time t during the last heating and cooling process of the sample was recorded, as shown in Figure 1. Figure 6 As shown in a. It can be found that the melting point T L When the temperature of the sample is at a certain temperature T N The sudden rise in temperature corresponds to the nucleation and growth of the primary solid phase from the melt, that is, the beginning of the solidification process. The supercooling ΔT is defined as the melting point T of the substance. L and nucleation temperature T N In this example, ΔT is about 96°C.

[0115] After solidification, the sample was taken out and the macroscopic morphology of the sample was as follows: Figure 6 As shown in b. It can be seen that the sample has a spherical morphology as a whole and no surface instability occurs. Figure 1 The macroscopic morphology judgment process shown in the figure is shown in the figure. The values ​​of y1, y2, y3 and y4 obtained by substituting various numerical values ​​are 5.92, 1189.94, 1.56, 5.46×10 -5 , constructing a coordinate system with y1-y2 as the ordinate and y3-y4 as the abscissa, it can be seen that the corresponding data points in this example are in the fourth quadrant (y1-y2<0, y3-y4>0), and the sample should have a spherical morphology, which is consistent with the experimental observation results.

[0116] This shows that it is reliable to use melt processing parameter data to predict the melt macromorphology.

[0117] Example 6:

[0118] A method for designing the macroscopic morphology of metal melts based on Co 81.5 B 18.5 Taking alloy as an example, the specific expression method is:

[0119] The sample was heated from room temperature to 1150°C at a rate of 20°C / min in a static magnetic field of 25T and a gradient magnetic field of 0.02T / m. This temperature was slightly above the melting point. The sample was then kept warm for 3 minutes. The sample was then rapidly heated to 1170°C at a rate of 100°C / min and kept warm for 5 minutes. The sample was then cooled at a rate of 20°C / min. Only a single cycle was performed. The obtained ΔT data had some fluctuations, but the characteristic temperature value could still be determined. The curve of T changing with time t during the entire process was recorded, as shown in the following example: Figure 7 As shown in a. It can be found that the melting point T L When the temperature of the sample is at a certain temperature T N The sudden rise in temperature corresponds to the nucleation and growth of the primary solid phase from the melt, that is, the beginning of the solidification process. The supercooling ΔT is defined as the melting point T of the substance. L and nucleation temperature T N In this example, ΔT is about 81°C.

[0120] After solidification, the sample was taken out and the macroscopic morphology of the sample was as follows: Figure 7 As shown in b. It can be seen that the sample as a whole presents an elongated morphology, and the surface produces an uneven lotus peak structure, that is, the melt has obvious surface instability. Figure 1 The macroscopic morphology judgment process shown in the figure is shown in the figure. The values ​​of y1, y2, y3 and y4 obtained by substituting various numerical values ​​are 39.06×10 4 , 35.17, 25, 8.29×10 -2 , constructing a coordinate system with y1-y2 as the ordinate and y3-y4 as the abscissa, it can be seen that the corresponding data points in this example are in the first quadrant (y1-y2>0, y3-y4>0), and the sample should present a lotus-shaped elongated morphology, which is consistent with the experimental observation results.

[0121] This shows that it is reliable to use melt processing parameter data to predict the melt macromorphology.

[0122] Example 7:

[0123] A method for designing the macroscopic morphology of metal melts based on Co 81.5 B 18.5 Taking alloy as an example, the specific expression method is:

[0124] The sample was heated from room temperature to 1450°C at a rate of 20°C / min in a static magnetic field of 25T and a gradient magnetic field of 0.00002T / m. The temperature was kept at this temperature for 20 minutes, and then cooled at a rate of 30°C / min until solidification. The ΔT data obtained after a single cycle had some fluctuations, but the characteristic temperature value could still be determined. The curve of T versus time t during the entire process was recorded, as shown in the figure below: Figure 8As shown in a. It can be found that the melting point T L When the temperature of the sample is at a certain temperature T N The sudden rise in temperature corresponds to the nucleation and growth of the primary solid phase from the melt, that is, the beginning of the solidification process. The supercooling ΔT is defined as the melting point T of the substance. L and nucleation temperature T N In this example, ΔT is about 200°C.

[0125] After solidification, the sample was taken out and the macroscopic morphology of the sample was as follows: Figure 8 As shown in b. It can be seen that the sample as a whole presents an elongated water drop shape, and surface instability begins to occur. Figure 1 The macroscopic morphology judgment process shown in the figure is shown in the figure. The values ​​of y1, y2, y3 and y4 obtained by substituting various numerical values ​​are 39.06×10 4 , 6.22×10 -3 , 25, 42.01, constructing a coordinate system with y1-y2 as the ordinate and y3-y4 as the abscissa. It can be seen that the corresponding data points in this example are in the second quadrant (y1-y2>0, y3-y4<0), and the sample should have an elongated water droplet morphology, which is consistent with the experimental observation results.

[0126] This shows that it is reliable to use melt processing parameter data to predict the melt macromorphology.

[0127] Example 8:

[0128] A method for designing the macroscopic morphology of metal melts based on Co 83 B 17 Taking alloy as an example, the specific expression method is:

[0129] The sample was heated from room temperature to 1170°C at a rate of 60°C / min in a static magnetic field of 25T and a gradient magnetic field of 0.00003T / m. It was immediately cooled at the same rate and kept at 1080°C below the melting point for 2 hours. It was still in the melt state at this time. It was then cooled at the same rate until it solidified. The obtained ΔT data had some fluctuations, but the characteristic temperature value could still be determined. The curve of T changing with time t during the whole process of the sample was recorded, as shown in the figure below. Figure 9 As shown in a. It can be found that the melting point T L When the temperature of the sample is at a certain temperature T N The sudden rise in temperature corresponds to the nucleation and growth of the primary solid phase from the melt, that is, the beginning of the solidification process. The supercooling ΔT is defined as the melting point T of the substance. L and nucleation temperature T N In this example, ΔT is about 148°C.

[0130] After solidification, the sample was taken out and the macroscopic morphology of the sample was as follows: Figure 9 As shown in b. It can be seen that the sample as a whole presents an elongated water drop shape, and surface instability begins to occur. Figure 1 The macroscopic morphology judgment process shown in the figure is shown in the figure. The values ​​of y1, y2, y3 and y4 obtained by substituting various numerical values ​​are 39.06×10 4 , 1.85×10 -2 , 25, 38.10, constructing a coordinate system with y1-y2 as the ordinate and y3-y4 as the abscissa, it can be seen that the corresponding data points in this example are in the second quadrant (y1-y2>0, y3-y4<0), and the sample should have an elongated water droplet morphology, which is consistent with the experimental observation results.

[0131] This shows that it is reliable to use melt processing parameter data to predict the melt macromorphology.

[0132] Example 9:

[0133] A method for designing the macroscopic morphology of metal melts based on Co 83 B 17 Taking alloy as an example, the specific expression method is:

[0134] The sample was heated from room temperature to 1300°C at a rate of 30°C / min in a static magnetic field of 15T and a gradient magnetic field of 0.02T / m, kept at this temperature for 8 minutes, and then cooled at the same rate. Only a single cycle was performed. The obtained ΔT data had some fluctuations, but the characteristic temperature value could still be determined. The curve of T versus time t during the whole process was recorded, as shown in the figure below. Figure 10 As shown in a. It can be found that the melting point T L When the temperature of the sample is at a certain temperature T N The sudden rise in temperature corresponds to the nucleation and growth of the primary solid phase from the melt, that is, the beginning of the solidification process. The supercooling ΔT is defined as the melting point T of the substance. L and nucleation temperature T N In this example, ΔT is about 84°C.

[0135] After solidification, the sample was taken out and the macroscopic morphology of the sample was as follows: Figure 10 As shown in b. It can be seen that the sample as a whole presents an elongated morphology, and the surface produces an uneven lotus peak structure, that is, the melt has obvious surface instability. Figure 1 The macroscopic morphology judgment process shown in the figure is shown in the figure. The values ​​of y1, y2, y3 and y4 obtained by substituting various numerical values ​​are 5.06×10 4 , 38.98, 15, 8.12×10 -2, constructing a coordinate system with y1-y2 as the ordinate and y3-y4 as the abscissa, it can be seen that the corresponding data points in this example are in the first quadrant (y1-y2>0, y3-y4>0), and the sample should present a lotus-shaped elongated morphology, which is consistent with the experimental observation results.

[0136] This shows that it is reliable to use melt processing parameter data to predict the melt macromorphology.

[0137] Further, the points of the above two-dimensional coordinate system with y1-y2 as the vertical coordinate and y3-y4 as the horizontal coordinate are counted, as shown in the following example: Figure 11 As shown, according to the discrimination criteria, the third and fourth quadrants correspond to the region of spherical stable morphology, the first quadrant corresponds to the region of unstable morphology produced by lotus peaks, and the second quadrant corresponds to the region of elongated teardrop-like morphology. Examples 1 to 9 all fall within the corresponding ranges. Therefore, by controlling the melt processing parameters, the macroscopic morphology of the melt can be quantitatively predicted, providing an important basis for determining the microstructural morphology and final performance.

[0138] Obviously, those skilled in the art may make various changes and modifications to this technical solution without departing from the spirit and scope of this technical solution. Thus, if these modifications and variations of this technical solution fall within the scope of the claims of this technical solution and their equivalents, this technical solution is intended to include these modifications and variations.

Claims

1. A method for designing the macroscopic morphology of a metal melt, characterized in that: The steps include: Step 1: Place the metal sample in a high-magnetic field material processing device and apply a target high-magnetic field so that the sample is in an environment with a specific high-magnetic field strength H and a gradient magnetic field dH / dZ, with the direction of the gradient magnetic field being the same as the direction of gravity; Step 2: Perform multiple melt superheating and supercooling cycles to ensure that the supercooling degree ΔT of the sample remains unchanged before and after the magnetic field is applied. Record the temperature T-time t curve of the sample in the last heating and cooling stage and the change data of the mass m0 of the sample in the solidified state under the magnetic field. Obtain the starting temperature T of the peak of the cooling stage curve from the temperature T-time t curve. N , after the cycle is completed, remove the sample; Step 3: Based on the temperature T in step 2 and the mass m0 of the solidified sample under the magnetic field, calculate the first constant paramagnetic-ferromagnetic Curie transition temperature θ of the melt and the Curie constant C of the sample; Specifically include: Using the Faraday balance principle, the m0 data is converted into sample magnetic susceptibility , and its specific calculation formula is as follows: (1)； Where g is the gravity of the sample under the magnetic field when solidifying, m0 is the balance reading under the magnetic field when solidifying, that is, the mass of the sample in the solidified state under the magnetic field, m is the balance reading in the absence of a magnetic field, that is, the mass of the sample, dH / dZ is the gradient magnetic field value of the sample at the corresponding position in the device, and H is the target magnetic field strength applied; With temperature T as the horizontal axis, the inverse of the magnetic susceptibility As the vertical axis, draw a curve graph. The Curie-Weiss relationship with temperature T is as follows: (2)； Where C is the Curie constant of the sample, θ is the paramagnetic-ferromagnetic Curie transition temperature of the melt; Further linear fitting is performed on the drawn curve, and the slope of the curve k=1 / C, and the intercept with the temperature axis b=-θ / C, then C and θ can be calculated using the following formula: , (3)； Step 4: Establish a functional relationship between the dependent variable corresponding to the macroscopic morphology of the melt and the supercooling ΔT, the strong magnetic field intensity H, the strong magnetic field gradient dH / dZ, the paramagnetic-ferromagnetic Curie transition temperature θ and the second constant related to the sample, wherein the Curie constant C is used to calculate the second constant; the functional relationship is specifically the following formulas (4) to (7): (4)； (5)； (6)； (7)； Among them, y1, y2, y3 and y4 are four dependent variables corresponding to the macroscopic morphology of the melt, θ is obtained by formula (3), P1, P2, P3 and P4 are the second constants related to the material, T N is the nucleation temperature, which is calculated using formulas (8) to (11): (8)； (9)； (10)； (11)； Where C is obtained by formula (3), α is the dimensionless structure factor, ΔH f is the melting enthalpy of the substance, in J / mol, T m is the melting point of the substance, in K, μ0 is the vacuum permeability, which is 4π×10 -7 N / A 2 , N A is Avogadro's constant, which is 6.02×10 23 / mol,V m is the molar volume of the substance, in m 3 / mol, Δρ m is the difference between the density of the solid and liquid phases; Step 5: Determine the macroscopic morphology of the melt based on the dependent variable; specifically including: Determine the size of y1 and y2. When y1 is smaller than y2, the melt is a spherical melt. When y1 is greater than or equal to y2, the size of y3 and y4 is determined. When y3 is less than y4, the melt is a water drop-shaped melt. When y3 is greater than or equal to y4, the melt is a lotus-shaped melt.

2. The method for designing the macroscopic morphology of a metal melt according to claim 1, wherein: Before performing step 1, the method further includes: placing the metal sample in a strong magnetic field material processing device, heating the metal sample to a maximum heating temperature at a certain rate, keeping the temperature at that temperature for a certain period of time so that the melt is fully uniform, and then cooling the metal sample at the same rate, repeating the above heating and cooling processes until the supercooling ΔT obtained by multiple consecutive measurements is stable.

3. The method for designing the macroscopic morphology of a metal melt according to claim 2, wherein: The supercooling ΔT must be stable after at least 5 consecutive measurements.

4. The method for designing the macroscopic morphology of a metal melt according to claim 1, wherein: In step 2, when recording the temperature-time curves of the melt heating and cooling stages and the change data of the mass m0 of the sample in the solidified state under the magnetic field, a balance system equipped with a strong magnetic field material processing device is used for recording.

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