Method for designing macroscopic morphology of metal melt

Abstract

The invention provides a method for designing the macroscopic morphology of a metal melt, which comprises the following steps of: placing a metal sample in a high-intensity magnetic field material processing device, and applying a target high-intensity magnetic field, so that the sample is positioned in an environment with a specific high-intensity magnetic field intensity H and a gradient magnetic field dH / dZ; performing melt overheating and supercooling circulation for multiple times, ensuring that the supercooling degree delta T of the sample before and after the magnetic field is applied is not changed, recording a temperature-time curve of the sample in the last heating and cooling stage and change data of the mass m0 of the sample in a solidification state under the magnetic field, and obtaining an initial temperature TN of a peak generated by the curve in the cooling stage from the temperature-time curve; calculating to obtain a first constant paramagnetic-ferromagnetic Curie transition temperature theta of the melt and a Curie constant C of the sample; establishing a function relationship among dependent variables corresponding to the melt macroscopic morphology, delta T, H, dH / dZ, theta and second constants related to the sample, wherein C is used for calculating the second constants; and according to the dependent variables, the macroscopic morphology of the melt is judged.

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, the metal is in a molten state, and its macroscopic shape is affected by many factors. According to the liquid mean field theory model, the melt has a tendency to spheroidize under the action of external forces to reduce the surface area to reduce the surface energy. At the same time, under the action of gravity and external fields, there is a tendency to be more sharp locally. Under the competition of the two effects, the melt finally presents a variety of morphologies and shows unstable characteristics. The macroscopic morphology has an important influence on the distribution of microstructures and the final service performance. Continuously optimizing the organizational properties of metal materials is a hot issue of concern to academia and industry. Therefore, starting from the perspective of melt macroscopic morphology, it is necessary to actively predict and screen the melt macroscopic morphology structure by controlling the melt processing parameters. In addition, by drawing on the melt macroscopic morphology processing technology and applying it to the field of surface morphology modification of hydrogels, coatings, etc., products with different surface patterns can be produced, which can promote the development of product CMF design from the perspectives of appearance, artistry, and practicality.

[0003] At present, in the research on melt morphology instability, some researchers have successfully prepared a variety of different forms of Co macrostructures in pure Co metal, such as lotus, water drop, spherical, etc., by adjusting the external magnetic field intensity H, magnetic field gradient dH / dZ, supercooling ΔT, etc. of the melt in the supercooling solidification stage. It is worth noting that under the conditions of 12T strong magnetic field and near-zero gradient, the melt sample with ΔT at 320K to 330K is split into two along the central axis when solidifying, forming two more slender and sharp water drop structures. This shows that under different magnetic field conditions and supercooling conditions, various macroscopic morphology controls of Co melt can be achieved. However, it can be clearly seen that the Curie temperature of Co metal is relatively high, about 1393K, so when it is supercooled and solidified (the nucleation temperature is lower than the Curie temperature), the melt will show strong magnetism, so it is more susceptible to regulation in a magnetic field environment. For more metals and their alloy materials, their Curie temperatures are lower, and the materials are often far higher than the Curie temperature when solidifying, showing weak magnetism. It is unknown whether the magnetic field still has a regulatory effect. In addition, the laws of 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 of different morphologies by controlling parameters should be proposed. Summary of the invention

[0004] The present invention proposes a method for designing the macroscopic morphology of metal melts. The metal and alloy materials are subjected to a superheating and supercooling cycle treatment method, and the heating and cooling rates, heating temperatures, and holding times 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, and 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 melt macroscopic morphology.

[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 of a specific high-magnetic field strength H and a gradient magnetic field dH / dZ, and the direction of the gradient magnetic field is 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, and obtain the starting temperature T of the peak generated in the cooling stage curve from the temperature T-time t curve N , after the cycle is completed, take out the sample;

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

[0009] Step 4: Establishing 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;

[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, it also 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 to make the melt 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 explanation of the present invention, the supercooling degree 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 matching 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, and the specific calculation formula is as follows:

[0016]

[0017] Wherein, g is the gravity of the sample under the magnetic field when solidifying, m0 is the balance reading under the magnetic field when solidifying, i.e., the mass of the sample in the solidified state under the magnetic field, m is the balance reading without the magnetic field, i.e., 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 curve 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 explanation 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] 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, which 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 magnetic 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 (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 macroscopic morphology changes on microstructure and performance is often ignored by researchers. Macroscopic morphology 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 macroscopic morphology, and the melt composition is not limited to ferromagnetic materials such as Co, etc., covering a wider range, and is also used for weak 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 macroscopic morphology of the melt, thereby more intuitively and scientifically guiding the solidification structure and performance design.

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

[0040] The technical solution of the present technical solution 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 technical solution and constitute a part of the specification. Together with the embodiments of the technical solution, they are used to explain the technical solution and do not constitute a limitation of the technical solution. In the accompanying drawings:

[0042] Figure 1 It is a flow chart of melt macroscopic morphology 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] Fig. 9 The Co prepared in Example 8 of the present invention 83 B 17 Alloy macromorphology and supercooling curve.

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

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

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution 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, rather than 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 those skilled in the art to which the subject matter of 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 form unless otherwise explicitly defined herein.

[0055] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiments" in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood 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, wherein a superheating and supercooling cycle treatment method is used for metal and alloy materials, and the heating and cooling rates, the heating temperature, and the 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, and 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 a specific melt macroscopic morphology is formed after solidification.

[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 strong magnetic field material processing device and apply a target strong magnetic field so that the sample is in an environment of a specific strong magnetic field intensity H and a gradient magnetic field dH / dZ, and 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, and obtain the starting temperature T of the peak generated in 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 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 a certain time to make the melt 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 measured for more than 5 times is stable (with an average error of less than 2%).

[0063] The samples were processed in different ways, such as changing the heating temperature, holding time, and heating / cooling rate of the melt, and the cycles were repeated multiple times until the measured ΔT data did not fluctuate and the melt reached a stable state.

[0064] The setting of the above undercooling ΔT stabilization process can make the above step 2 keep the undercooling consistent with that before applying the magnetic field. For some metal samples, since the undercooling does not change much before and after the magnetic field is applied, the above undercooling ΔT stabilization process before applying the magnetic field may not be performed.

[0065] Specifically, the operation method to ensure that ΔT remains unchanged in step 2 is: when ΔT increases, the maximum heating temperature is reduced and the insulation time is shortened; when ΔT decreases, the maximum heating temperature is increased and the insulation 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: According to the temperature T in step 2 and the mass m0 of the sample in the solidified state under the magnetic field, the first constant paramagnetic-ferromagnetic Curie transition temperature θ of the melt and the Curie constant C of the sample are calculated.

[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] Wherein, g is the gravity of the sample under the magnetic field when solidifying, m0 is the balance reading under the magnetic field when solidifying, i.e., the mass of the sample in the solidified state under the magnetic field, m is the balance reading without the magnetic field, i.e., 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 curve 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 the 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] 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, which 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 magnetic 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 (m 3 / mol), Δρ m It is the difference between the density of the solid phase and the liquid phase. The above parameters can be queried for specific sample materials through physical and chemical handbooks.

[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, 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 macroscopic morphology provided by the present invention is verified below in conjunction with specific embodiments.

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

[0093] Embodiment 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 under a static magnetic field strength of 3T and a gradient magnetic field value of 23.235T / m, 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 a. It can be found that when the temperature rises above the melting point T L When the temperature of the sample is at a certain temperature T N 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 is spherical in shape and there is no surface instability. Figure 1 The macroscopic morphology judgment process shown in the figure, the y1, y2, y3 and y4 values ​​obtained by substituting various numerical calculations 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 present a spherical morphology, which is consistent with the experimental observation results, indicating that the use of melt processing parameter data to predict the melt macroscopic morphology is credible.

[0097] Embodiment 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 under a static magnetic field strength of 5T and a gradient magnetic field value of 38.725T / m, kept at this temperature 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 3 As shown in a. It can be found that when the temperature rises above the melting point T L When the temperature of the sample is at a certain temperature T NThe 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 is spherical in shape and there is no surface instability. Figure 1 The macroscopic morphology judgment process shown in the figure, the y1, y2, y3 and y4 values ​​obtained by substituting various numerical calculations are 625, 6472.68, 5, 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 credible to use melt processing parameter data to predict the melt macroscopic morphology.

[0102] Embodiment 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 under a static magnetic field strength of 20T and a gradient magnetic field value of 0.00005T / m, kept warm 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 changing with time t during the whole process of the sample was recorded, such as Figure 4 a. It can be found that when the temperature rises above the melting point T L When the temperature of the sample is at a certain temperature T N 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 droplet-like morphology, and surface instability begins to occur. Figure 1 The macroscopic morphology judgment process shown in the figure, the y1, y2, y3 and y4 values ​​obtained by substituting various numerical calculations are 1.60×104 , 5.76×10 -2 , 20, 30.36, construct 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 credible to use melt processing parameter data to predict the melt macroscopic morphology.

[0107] Embodiment 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, kept warm 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 changing with time t during the whole process of the sample was recorded, such as Figure 5 As shown in a. It can be found that when the temperature rises above the melting point T L When the temperature of the sample is at a certain temperature T N 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, the y1, y2, y3 and y4 values ​​obtained by substituting various numerical calculations 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 an elongated lotus-like morphology, which is consistent with the experimental observation results.

[0111] This shows that it is credible to use melt processing parameter data to predict the melt macroscopic morphology.

[0112] Embodiment 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 under a static magnetic field strength of 1.56T and a gradient magnetic field value of 23.235T / m, and 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 2. Figure 6 As shown in a. It can be found that when the temperature rises above the melting point T L When the temperature of the sample is at a certain temperature T N The supercooling ΔT is defined as the melting point T of the substance. L and nucleation temperature T N In this case, 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 is spherical in shape and there is no surface instability. Figure 1 The macroscopic morphology judgment process shown in the figure, the y1, y2, y3 and y4 values ​​obtained by substituting various numerical calculations 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 credible to use melt processing parameter data to predict the melt macroscopic morphology.

[0117] Embodiment 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 under a static magnetic field strength of 25T and a gradient magnetic field value of 0.02T / m. This temperature was slightly higher than the melting point. It was then kept warm for 3 minutes, and then rapidly heated to 1170°C at a rate of 100°C / min, kept warm for 5 minutes, and 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 whole process of the sample was recorded, such as Figure 7 As shown in a. It can be found that when the temperature rises above the melting point T L When the temperature of the sample is at a certain temperature T N 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, the y1, y2, y3 and y4 values ​​obtained by substituting various numerical calculations 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 an elongated lotus-like morphology, which is consistent with the experimental observation results.

[0121] This shows that it is credible to use melt processing parameter data to predict the melt macroscopic morphology.

[0122] Embodiment 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 under a static magnetic field strength of 25T and a gradient magnetic field value of 0.00002T / m, kept warm for 20 minutes, and then continued to cool at a rate of 30°C / min until solidified. The ΔT data obtained after a single cycle produced some fluctuations, but the characteristic temperature value can still be determined. The curve of T changing with time t during the whole process of the sample was recorded, such as Figure 8a. It can be found that when the temperature rises above the melting point T L When the temperature of the sample is at a certain temperature T N 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 droplet-like morphology, and surface instability begins to occur. Figure 1 The macroscopic morphology judgment process shown in the figure, the y1, y2, y3 and y4 values ​​obtained by substituting various numerical calculations are 39.06×10 4 , 6.22×10 -3 , 25, 42.01, and construct 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 credible to use melt processing parameter data to predict the melt macroscopic morphology.

[0127] Embodiment 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, and immediately cooled at the same rate. After cooling to 1080°C below the melting point and keeping the temperature for 2 hours, it was still in the melt state. Then it continued to cool at the same rate until solidification. 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, such as Fig. 9 a. It can be found that when the temperature rises above the melting point T L When the temperature of the sample is at a certain temperature T N 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 Fig. 9 As shown in b. It can be seen that the sample as a whole presents an elongated water droplet-like morphology, and surface instability begins to occur. Figure 1 The macroscopic morphology judgment process shown in the figure, the y1, y2, y3 and y4 values ​​obtained by substituting various numerical calculations 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 credible to use melt processing parameter data to predict the melt macroscopic morphology.

[0132] Embodiment 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 warm 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 changing with time t during the whole process of the sample was recorded, such as Fig.10 As shown in a. It can be found that when the temperature rises above the melting point T L When the temperature of the sample is at a certain temperature T N 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 Fig.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, the y1, y2, y3 and y4 values ​​obtained by substituting various numerical calculations 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 an elongated lotus-like morphology, which is consistent with the experimental observation results.

[0136] This shows that it is credible to use melt processing parameter data to predict the melt macroscopic morphology.

[0137] The points of the above two-dimensional coordinate system with y1-y2 as the ordinate and y3-y4 as the abscissa are further counted, such as Fig.11 As shown, according to the discrimination conditions, the third and fourth quadrants correspond to the spherical stable morphology area, the first quadrant corresponds to the unstable morphology area produced by the lotus peak, and the second quadrant corresponds to the water droplet-shaped elongated morphology area. Examples 1 to 9 all meet the corresponding range. Therefore, by regulating the melt processing parameters, the macroscopic morphology of the melt can be quantitatively predicted, thereby providing an important basis for judging the microstructure morphology and final performance.

[0138] Obviously, those skilled in the art can make various changes and modifications to the technical solution without departing from the spirit and scope of the technical solution. Thus, if these modifications and variations of the technical solution fall within the scope of the claims of the technical solution and their equivalents, the technical solution is also 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 of a specific high-magnetic field strength H and a gradient magnetic field dH / dZ, and the direction of the gradient magnetic field is 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, and obtain the starting temperature T of the peak generated in the cooling stage curve from the temperature T-time t curve N , after the cycle is completed, take out the sample; Step 3: According to the temperature T in step 2 and the mass m0 of the solidified sample under the magnetic field, the first constant paramagnetic-ferromagnetic Curie transition temperature θ of the melt and the Curie constant C of the sample are calculated; Step 4: Establishing 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; Step 5: Determine the macroscopic morphology of the melt based on the dependent variable.

2. The method for designing the macroscopic morphology of a metal melt according to claim 1, characterized in that: Before performing step 1, the method also 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 period of time to make the melt fully uniform, then cooling it at the same rate, and 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, characterized in that: 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, characterized in that: 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 matched with the strong magnetic field material processing device is used for recording.

5. The method for designing the macroscopic morphology of a metal melt according to claim 1, characterized in that: 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: Using the Faraday balance principle, the m0 data is converted into the sample magnetic susceptibility χ, and the specific calculation formula is as follows: Wherein, g is the gravity of the sample under the magnetic field when solidifying, m0 is the balance reading under the magnetic field when solidifying, i.e., the mass of the sample in the solidified state under the magnetic field, m is the balance reading without the magnetic field, i.e., 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 abscissa and the inverse of magnetic susceptibility 1 / χ as the ordinate, a curve is drawn. 1 / χ and temperature T satisfy the Curie-Weiss relationship as follows: 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:

6. The method for designing the macroscopic morphology of a metal melt according to claim 5, characterized in that: The functional relationship established in step 4 is specifically the following formulas (4) to (7): y1=H 4 (4) y3=H (6) 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, which are calculated by formulas (8) to (11) respectively: 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 magnetic 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 (m 3 / mol), Δρ m is the difference between the density of the solid and liquid phases.

7. The method for designing the macroscopic morphology of a metal melt according to claim 6, characterized in that: In step 5, judging the macroscopic morphology of the melt according to the dependent variable specifically includes: 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.

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