A method for high-throughput high-entropy alloy composition design

Abstract

The application provides a high-throughput high-entropy alloy component design method, comprising the following steps: S1) preparing an initial sample of pure metal or alloy; S2) preparing a master alloy ingot according to the high-entropy alloy component; S3) assembling the initial sample at the bottom of a mold shell, fixing the mold shell on a directional solidification furnace pulling device, and exposing a part of the initial sample from the liquid level of a cooling tank, and immersing the remaining part into the cooling liquid in the cooling tank; S4) assembling the master alloy ingot on the upper part of an induction dripping system of the directional solidification furnace, and turning on the heating power supply of the directional solidification furnace; S5) turning on the induction dripping system until the master alloy ingot is melted and dripped into the mold shell, and then cooling and solidifying after heat preservation. The high-throughput sample component prepared by the method provided in the application is uniform and linear, and the component screening precision is higher; the high-throughput sample with single-element or multi-element coupling change can be efficiently prepared, the performance data reliability is higher, and the industrial application potential of the alloy is greater.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy technology, and in particular to a method for designing high-throughput high-entropy alloy compositions. Background Technology

[0002] High-entropy alloys are a disruptive new alloy system developed in recent years. They are composed of five or more principal elements, mixed in equiatomic or near-equiatomic ratios, with each principal element accounting for 5% to 35% of the total atomic content. Therefore, they are also known as multi-principal-element, equiatomic, or near-equiatomic alloys. Compared to traditional alloys, high-entropy alloys exhibit a high-entropy effect thermodynamically, a slow diffusion effect kinetically, a lattice distortion effect structurally, and a cocktail effect in terms of performance. Under the coupled effect of these multiple mechanisms, high-entropy alloys possess many superior properties unmatched by traditional materials, and are thus considered one of the key materials that hold the promise of solving current bottlenecks in material performance in engineering fields.

[0003] With the further development of research in the field of high-entropy alloys, the definition of high-entropy alloys has been expanded, and efficient composition design and preparation methods for high-entropy alloys have become key to their industrial application. Currently, commonly used composition design and efficient preparation methods for high-entropy alloy composition screening include discrete template coating, multi-target co-sputtering, and laser melting deposition. However, these methods generally have the following problems: First, the equipment cost is high, there are many control parameters, and the operation process is complex; second, the prepared samples can only be pre-designed independent composition points, and it is impossible to prepare samples with linear compositional changes, resulting in insufficient accuracy in composition screening; third, the prepared sample size is generally small, and the mechanical properties of the alloy can only be evaluated through compression tests, and the obtained alloy composition may not have optimal performance after industrial production.

[0004] The above-mentioned problems limit the efficiency of high-entropy alloy composition screening. Therefore, there is an urgent need to develop low-cost, high-precision composition design and efficient preparation methods capable of preparing large-size high-entropy alloy samples. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a method for designing high-throughput high-entropy alloy compositions. The method provided in this application can design different high-entropy alloy compositions simultaneously with higher accuracy and higher reliability of performance data.

[0006] In view of this, this application provides a method for high-throughput, high-entropy alloy composition design, comprising the following steps:

[0007] S1) Prepare an initial sample of a pure metal or alloy; the elements of the pure metal or alloy are selected from one or two of Fe, Co, Ni, Al, Ti, Cu, Si, Ta, Nb, Cr, Zr, V, Mo, Hf, C, and B.

[0008] S2) The raw materials are prepared according to the high-entropy alloy composition and then a master alloy ingot is prepared; the master alloy ingot is prepared from at least three elements selected from Fe, Co, Ni, Al, Ti, Cu, Si, Ta, Nb, Cr, Zr, V, Mo, Hf, C, and B;

[0009] S3) The initial sample is assembled at the bottom of the shell, the shell is fixed on the directional solidification furnace pull-out device, and the position of the shell is adjusted so that a part of the initial sample is exposed above the liquid surface of the cooling tank, and the rest is immersed in the cooling liquid of the cooling tank; the initial sample in the shell can be a sample of the same type or a sample of different types.

[0010] S4) Assemble the master alloy ingot on the upper part of the induction dripping system of the directional solidification furnace, and turn on the heating power supply of the directional solidification furnace to make the temperature higher than the melting point of the initial sample and the melting point of the master alloy ingot.

[0011] S5) Turn on the induction dripping system until the master alloy ingot melts and drips into the mold shell. After heat preservation, the initial sample and the melt of the master alloy ingot form a gradient transition zone, and then cool and solidify.

[0012] Preferably, the shell is a ceramic shell, which is prepared by investment casting.

[0013] Preferably, the height of the initial sample exposed above the liquid surface in the cooling tank is 1 / 4 to 1 / 2 of the initial sample, and the coolant is a gallium indium tin alloy.

[0014] Preferably, the directional solidification furnace is maintained under vacuum or purged with inert gas, wherein the vacuum level is 3 × 10⁻⁶. -3 ~9×10 -1 Pa.

[0015] Preferably, the temperature of the directional solidification furnace is 50-100°C above the melting point of the initial sample and the melting point of the master alloy ingot.

[0016] Preferably, in step S4), the heating rate of the directional solidification furnace is 10~15℃ / min, and the holding time after reaching the set temperature is 20~40min.

[0017] Preferably, in step S5), the power of the induction coil of the induction dripping system is 30~40kW, the rotation speed of the master alloy ingot is 5~10rad / min, the feed rate is 0.3~0.5mm / s, and the heat preservation time is 0~30min.

[0018] Preferably, the cooling and solidification specifically refers to:

[0019] The pulling device is activated at a moving speed of 0.001~20mm / s, and the shell moves vertically from top to bottom into the cooling tank;

[0020] Alternatively, turn off the heating power of the directional solidification furnace to allow the alloy melt inside the mold to cool and solidify naturally.

[0021] Preferably, after step S5), the method further includes:

[0022] The solidified high-entropy alloy sample was removed and then subjected to stress-relief annealing.

[0023] The high-entropy alloy samples after stress-relief annealing were longitudinally sectioned, and the composition, microstructure and mechanical properties of the bonding zone were analyzed to screen out high-entropy alloy compositions with excellent performance.

[0024] Preferably, the stress-relief annealing temperature is 300~900℃, and the holding time is 1~4h.

[0025] This application provides a method for high-throughput high-entropy alloy composition design. First, an initial sample of a pure metal or alloy is prepared. Then, a master alloy ingot is prepared according to the high-entropy alloy composition. Next, the initial sample is assembled at the bottom of a mold shell. Finally, the initial sample and the master alloy ingot are melted using a directional solidification furnace, forming a gradient transition zone between the molten initial sample and the master alloy ingot. After cooling and solidification, the designed high-throughput high-entropy alloy composition is obtained. The method provided in this application, by designing the initial sample and using the molten high-entropy alloy master alloy ingot to drip onto the surface of the molten initial sample, forms a gradient transition zone, resulting in a uniform and linear high-entropy alloy composition, higher screening accuracy, and efficient preparation of high-throughput high-entropy alloy samples with single-element or multi-element coupled variations. The obtained performance data is also more reliable. Attached Figure Description

[0026] Figure 1 This is a top view showing the schematic diagram and actual object of the shell of the present invention;

[0027] Figure 2 This is a schematic diagram of the equipment and shell location for preparing high-throughput high-entropy alloy samples according to the present invention;

[0028] Figure 3 This is a schematic diagram of the process for preparing high-throughput, high-entropy alloy samples according to the present invention.

[0029] Figure 4 Photograph of the cylindrical high-throughput high-entropy alloy sample prepared in Example 1 of this invention;

[0030] Figure 5 This is a micrograph of the bonding region of a high-entropy alloy cylindrical sample with a linear gradient change region of Ti and Al elements after being cut open, as shown in Example 2 of this invention.

[0031] Figure 6 The image shows the elemental line scan spectrum of the bonding region after cutting a cylindrical high-entropy alloy sample with a linear gradient change region of Ti and Al elements prepared in Example 2 of this invention. Detailed Implementation

[0032] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0033] In view of the low efficiency of high-entropy alloy composition screening in existing technologies, this application provides a high-throughput high-entropy alloy composition design method. This method uses single-element or multi-element coupled samples as base samples, combined with a high-entropy alloy master ingot, to form a gradient-transition high-entropy alloy sample. Finally, performance screening is performed to obtain accurately customized high-entropy alloy compositions. Furthermore, the initial sample is not limited to a single sample, thus achieving high-throughput high-entropy alloy composition design. Specifically, this invention discloses a high-throughput high-entropy alloy composition design method, including the following steps:

[0034] S1) Prepare an initial sample of a pure metal or alloy; the elements of the pure metal or alloy are selected from one or two of Fe, Co, Ni, Al, Ti, Cu, Si, Ta, Nb, Cr, Zr, V, Mo, Hf, C, and B.

[0035] S2) Except for the elements in step S1), the raw materials are prepared according to the high-entropy alloy composition and then prepared into a master alloy ingot; the master alloy ingot is prepared from at least three elements selected from Fe, Co, Ni, Al, Ti, Cu, Si, Ta, Nb, Cr, Zr, V, Mo, Hf, C, and B.

[0036] S3) The initial sample is assembled at the bottom of the mold shell, the mold shell is fixed on the directional solidification furnace pulling device, and the position of the mold shell is adjusted so that a part of the initial sample is exposed above the liquid surface of the cooling tank, and the rest enters the cooling tank; the initial sample in the mold shell can be a sample of the same type or a sample of different types.

[0037] S4) Assemble the master alloy ingot on the upper part of the induction dripping system of the directional solidification furnace, and turn on the heating power supply of the directional solidification furnace to make the temperature higher than the melting point of the initial sample and the melting point of the master alloy ingot.

[0038] S5) Turn on the induction dripping system until the master alloy ingot melts and drips into the mold shell. After heat preservation, the initial sample and the melt of the master alloy ingot form a gradient transition zone, and then cool and solidify.

[0039] In the high-throughput, high-entropy alloy composition design method provided in this application, step S1) first prepares an initial sample of a pure metal or alloy. The elements of the pure metal or alloy are selected from one or two of Fe, Co, Ni, Al, Ti, Cu, Si, Ta, Nb, Cr, Zr, V, Mo, Hf, C, and B. That is, an initial sample of the aforementioned pure metal can be prepared alone, or an initial sample of two elements can be prepared. The element ratio of the initial sample of the two elements can be formulated according to requirements. In a specific embodiment, pure metal Fe rods, pure metal Co rods, pure metal Ni rods, pure metal Al rods, and pure metal Ti rods are prepared; or NiTi master alloy rods, TiAl master alloy rods, or NiCr50 master alloy rods are prepared. The initial alloy rods are prepared according to conventional techniques used by those skilled in the art, such as casting, forging, powder metallurgy, or additive manufacturing. The melting point of the initial sample is T. A .

[0040] In step S2), raw materials are prepared according to the high-entropy alloy composition to form a master alloy ingot; the high-entropy alloy composition is selected from at least three elements from Fe, Co, Ni, Al, Ti, Cu, Si, Ta, Nb, Cr, Zr, V, Mo, Hf, C, and B, that is, three or more of the above elements are selected as needed to prepare the composition of the high-entropy alloy; for example, the master alloy ingot is a FeCoNiAl high-entropy alloy master alloy ingot with an equal atomic ratio or a (FeCoNiCr) ingot with a specific atomic ratio. 96 Al2Ti2 high-entropy alloy master alloy ingot; the master alloy ingot can be obtained by melting and casting in a vacuum consumable furnace, or by melting and casting in a vacuum induction furnace. The melting point of the master alloy ingot is T. B .

[0041] In step S3), the initial sample is assembled onto the bottom of the mold shell. In this step, the mold shell is a structure well-known to those skilled in the art, and this application does not impose any particular limitations on it. Preferably, the mold shell is a ceramic mold shell. The specific placement structure of the initial sample in the mold shell is as follows: Figure 1As shown, in the left figure, 1 is the gate, 2 is the main body of the rod-shaped sample shell, 3 is the initial sample pre-placed in the shell, and 4 is the base; the right figure is a top view of the initial sample in the shell; in this example shell, three initial samples are pre-placed, and the initial samples are only pre-placed at the bottom of the shell, while the upper part is the original rod-shaped shell, which is used to drip high-entropy alloy melt. In this application, the initial sample pre-placed inside the shell can be the same sample or different samples. Among the different sample selections, a single-element sample or a two-element coupled sample can be selected. For example, the bottom of the shell can be equipped with five kinds of pure metal rods: pure metal Fe rod, pure metal Co rod, pure metal Ni rod, pure metal Al rod, and pure metal Ti rod; or it can be equipped with three kinds of intermediate alloy rods: NiTi intermediate alloy rod, TiAl intermediate alloy rod, and NiCr50 intermediate alloy rod, or a combination of pure metal rods and intermediate alloy rods: pure metal Fe rod, pure metal Co rod, NiTi intermediate alloy rod, and TiAl intermediate alloy rod.

[0042] After the mold shell is prepared, it is fixed on the pulling device of the directional solidification furnace. The position of the mold shell is adjusted by the pulling device so that a part of the initial sample is exposed above the liquid surface of the cooling tank, while the rest is immersed in the coolant. The directional solidification furnace is a directional solidification furnace for preparing high-entropy alloys, which is well known to those skilled in the art. It includes a stretching device, a heating device, an induction dripping system, a cooling tank, etc. The specific positions of these components are well known to those skilled in the art, and this application does not impose any special restrictions on them. The height of the initial sample exposed above the liquid surface of the cooling tank is 1 / 4 to 1 / 2 of the initial sample, more specifically 1 / 4, 1 / 3, or 1 / 2. The coolant can be selected from gallium indium tin alloy.

[0043] In step S4), the master alloy ingot is assembled on the upper part of the induction dripping system of the directional solidification furnace, specifically as follows: Figure 2 As shown, Figure 2 Component 5 is a high-entropy alloy master alloy ingot, 11 is an induction coil, 12 is an upper cover plate, 13 is a heating element, 14 is the furnace body, 15 is a cooling tank, 16 is a gallium-indium-tin coolant, and 17 is a tension rod. Then, the vacuum pump of the directional solidification furnace is turned on to achieve a vacuum level of 3 × 10⁻⁶ inside the equipment. -3 ~9×10 -1 Pa, maintain vacuum or provide protection with inert gas; turn on the heating power of the directional solidification furnace to make the temperature higher than the melting point of the initial sample and the melting point of the master alloy ingot; specifically, the temperature of the directional solidification furnace is the melting point T of the initial sample. A The melting point T of the master alloy ingot BThe temperature is 50~100℃, the heating rate of the directional solidification furnace is 10~15℃ / min, and the holding time after reaching the temperature is 20~40min; to ensure that the shell is fully preheated and that the part of the initial sample exposed at the bottom of the cooling tank melts.

[0044] In step S5), the induction dripping system is activated to melt the high-entropy alloy and drip it into the mold shell, bringing it into contact with the molten initial sample in the mold shell. The induction dripping system has an induction coil power of 30-40 kW, a master alloy ingot rotation speed of 5-10 rad / min, and a feed rate of 0.3-0.5 mm / s. Specifically, the induction dripping system has an induction coil power of 35-40 kW, a master alloy ingot rotation speed of 6-8 rad / min, and a feed rate of 0.3-0.4 mm / s. After dripping, the system is held at a certain temperature to allow the melt in the bonding zone between the initial sample and the high-entropy alloy to mix and diffuse, forming a gradient transition zone. Finally, cooling and solidification are performed, thus achieving the design of a high-throughput high-entropy alloy composition in the linear gradient change zone. The cooling and solidification specifically involves:

[0045] When the pulling device is activated at a moving speed of 0.001~20mm / s, the shell moves vertically from top to bottom into the cooling tank, causing the alloy melt inside the shell to solidify; or the heating power of the directional solidification furnace is turned off, allowing the alloy melt inside the shell to cool and solidify naturally.

[0046] The flowchart illustrating the high-throughput, high-entropy alloy composition design described in this application is as follows: Figure 3 As shown, 6 is the liquid region formed by dripping high-entropy alloy into the mold shell after induction melting; the process is as follows: first, assemble the initial sample, then assemble the high-entropy alloy master alloy ingot, drip high-entropy alloy melt, then the high-entropy alloy melt and the initial sample melt form a liquid region, and finally form an element diffusion region.

[0047] After preparing the above-mentioned high-throughput high-entropy alloy samples, this application further includes a screening process, specifically as follows:

[0048] The solidified high-entropy alloy sample was removed and then subjected to stress-relief annealing.

[0049] The high-entropy alloy samples after stress-relief annealing were longitudinally sectioned, and the composition, microstructure and mechanical properties of the bonding zone were analyzed to screen out high-entropy alloy compositions with excellent performance.

[0050] In the above process, the stress-relief annealing temperature is 300~900℃, and the holding time is 1~4h; the composition of the bonding area is tested by electron probe microanalysis, the microstructure is tested by metallographic microscope, scanning electron microscope, and transmission electron microscope, and the mechanical properties mainly include microhardness and tensile properties are tested.

[0051] The high-throughput, high-entropy alloy composition design method provided in this application is particularly suitable for preparing high-entropy alloy samples with coupled variations of one or two elements, and more specifically includes the following steps:

[0052] 1. Raw material and shell preparation:

[0053] (1) Depending on the type and proportion of one or two elements to be studied, pure metal or alloy bars or plates are prepared by one or more of the following methods: casting, forging, powder metallurgy, or additive manufacturing, with a melting point of T. A ;

[0054] The pure metal or alloy rods or plates are composed of one or two elements selected from Fe, Co, Ni, Al, Ti, Cu, Si, Ta, Nb, Cr, Zr, V, Mo, Hf, C, and B.

[0055] (2) Raw materials are prepared according to the high-entropy alloy composition, and the alloy is melted and cast into a master alloy ingot using a vacuum consumable furnace or a vacuum induction furnace. The melting point of the master alloy is T. B ;

[0056] The high-entropy alloy master alloy ingot is composed of at least three elements selected from Fe, Co, Ni, Al, Ti, Cu, Si, Ta, Nb, Cr, Zr, V, Mo, Hf, C, and B.

[0057] (3) Prepare rod-shaped or plate-shaped ceramic shells for specimens using investment casting;

[0058] 2. Preparation and composition screening of high-entropy alloy samples:

[0059] Efficient preparation of high-entropy alloys with linear gradient regions was achieved using a modified Bridgeman directional solidification apparatus.

[0060] (1) Assemble pure metal or alloy rods or plates at the bottom of the ceramic shell and fix them as a whole on the stretching rod of the directional solidification furnace. Different kinds of pure metal or alloy rods can be assembled in the same shell as needed to achieve the preparation of high-throughput samples of single element or two elements coupled together. Adjust the height of the stretching rod so that 1 / 4 to 1 / 2 of the pure metal or alloy rods or plates are exposed above the liquid surface of the cooling tank, and the rest are completely immersed in the cooling tank. The coolant in the cooling tank is a gallium indium tin alloy.

[0061] (2) Assemble the high-entropy alloy master alloy ingot on the upper part of the induction drip coil of the directional solidification furnace;

[0062] (3) Turn on the vacuum pump of the directional solidification furnace to achieve a vacuum level of 3×10⁻⁶ inside the equipment. -3 ~9×10 -1 Pa, maintain vacuum or provide protection with inert gas;

[0063] (4) Set the furnace temperature to T A and T B At a temperature 50-100°C higher than the specified temperature, turn on the power to the directional solidification furnace to raise the temperature of the upper and lower heating elements inside the furnace at a rate of 10-15°C / min. After reaching the specified temperature, hold the temperature for 20-40 minutes to ensure that the ceramic shell is fully preheated. At the same time, the part of the pure metal or alloy rod or plate at the bottom of the shell that is exposed in the cooling tank will melt.

[0064] (5) Turn on the induction dripping system, adjust the power of the induction coil to 30~35kW, the rotation speed of the high entropy alloy ingot to 8~10rad / min, and the feed rate to 0.3~0.4mm / s until a sufficient amount of high entropy alloy is melted, then turn off the induction dripping system.

[0065] (6) After the high-entropy alloy dripping is completed, keep it warm for 0~30 min to allow the melt of the pure metal or alloy and the high-entropy alloy bonding zone to mix and diffuse, forming a gradient transition zone;

[0066] (7) When the pulling device is turned on at a moving speed of 0.001~20mm / s, the ceramic shell moves vertically from top to bottom into the cooling tank, so that the alloy melt inside the shell solidifies; or the heating power of the directional solidification furnace is turned off, so that the alloy melt inside the shell cools and solidifies naturally, thereby completing the efficient preparation of high-entropy alloy samples with linear gradient change zone.

[0067] 3. Ingredient screening:

[0068] (1) After the temperature inside the furnace has cooled naturally to room temperature, the high-entropy alloy sample is taken out from the directional solidification furnace and the shell is removed by sandblasting or machining to obtain the high-entropy alloy sample.

[0069] (2) Place the high-entropy alloy sample in a box-type resistance furnace and keep it at 300~900℃ for 1~4h to remove residual stress;

[0070] (3) The high-entropy alloy sample is cut along the longitudinal direction. The composition distribution and changes in the bonding area are tested by electron probe microanalysis. The microstructure of the bonding area between the pure metal or alloy and the high-entropy alloy is observed by metallographic microscope, scanning electron microscope and transmission electron microscope. The room temperature and high temperature microhardness of the bonding area are tested, and the tensile properties are tested, so as to accurately screen out the high-entropy alloy composition with excellent performance.

[0071] This application provides a method for high-throughput high-entropy alloy composition design, which produces high-throughput high-entropy alloy samples with uniform and linear composition and higher composition screening accuracy; it can efficiently prepare high-throughput samples with single-element or multi-element coupled variations; it can prepare large-size high-throughput samples, and the obtained performance data has higher reliability, with greater potential for industrial application of the alloy; the equipment cost is significantly reduced, and the control parameters are greatly reduced, simplifying the operation process.

[0072] To further understand the present invention, the preparation method of the high-throughput high-entropy alloy provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0073] Example 1

[0074] The preparation of a high-entropy alloy sample with a nominal composition of FeCoNiAl as the main body and exhibiting a gradient transition region of Fe, Co, Ni, Al, and Ti elements, with a sample size of Φ15mm×120mm, was achieved through the following steps:

[0075] 1. Raw material and shell preparation:

[0076] (1) Pure metal Fe, Co, Ni, Al and Ti rods are used, with melting points of 1538℃, 1495℃, 1455℃, 660℃ and 1668℃ respectively. The surface of the rods is processed to a roughness Ra=3.2μm and the size is Φ14.5mm×60mm.

[0077] (2) The FeCoNiAl high-entropy alloy was prepared by raw material formulation according to the same atomic ratio, with the corresponding weight percentages as follows: Fe 27.8%; Co 29.4%; Ni 29.3%; Al 13.5%; it was melted twice in a vacuum induction melting furnace to ensure the uniformity of composition and cast into a high-entropy alloy master alloy ingot with a melting point of about 1580℃.

[0078] (3) The rod-shaped ceramic shell for the sample was prepared by investment casting.

[0079] 2. Preparation and composition screening of high-entropy alloy samples:

[0080] The improved Bridgeman directional solidification apparatus was used to achieve the efficient preparation of high-entropy alloys with linear gradient regions of Fe, Co, Ni, Al, and Ti.

[0081] (1) Pure metal Fe, Co, Ni, Al, and Ti rods are respectively assembled at the bottom of the ceramic shell (see schematic diagram for details). Figure 1As shown in the diagram), the entire assembly is fixed to the tension rod of the directional solidification furnace; the height of the tension rod is adjusted so that half of the pure metal rod is exposed above the liquid surface of the cooling tank, while the remaining part is completely immersed in the cooling tank. The coolant in the cooling tank is a gallium indium tin alloy (see the schematic diagram for details). Figure 2 (as shown)

[0082] (2) Assemble the FeCoNiAl high-entropy alloy master alloy ingot on the upper part of the induction drip coil of the directional solidification furnace (see schematic diagram for details). Figure 2 (as shown)

[0083] (3) Turn on the vacuum pump of the directional solidification furnace to achieve a vacuum level of 10 in the equipment. -1 Pa;

[0084] (4) Set the furnace temperature to 1720℃, turn on the heating power of the directional solidification furnace to raise the temperature of the upper and lower heating bodies in the furnace at a rate of 15℃ / min, and keep it at the temperature for 30 minutes after reaching the temperature to ensure that the ceramic shell is fully preheated. At the same time, the part of the pure metal rod at the bottom of the shell that is exposed in the cooling tank melts.

[0085] (5) Turn on the induction drip system, adjust the power of the induction coil to 30kW, the rotation speed of the FeCoNiAl high entropy alloy master alloy ingot to 8rad / min, and the feed rate to 0.3mm / s, until a sufficient amount of high entropy alloy is melted, then turn off the induction drip system;

[0086] (6) After the high-entropy alloy dripping is completed, keep it at a temperature for 20 minutes to allow the melt in the bonding zone of the pure metal and the high-entropy alloy to mix and diffuse, forming a gradient transition zone;

[0087] (7) When the pulling device is turned on at a moving speed of 0.2 mm / s, the ceramic shell moves vertically from top to bottom into the cooling tank, causing the alloy melt inside the shell to solidify, thereby completing the efficient preparation of a high-entropy alloy sample with a linear gradient change region of Fe, Co, Ni, Al and Ti.

[0088] 3. Ingredient screening:

[0089] (1) After the furnace temperature has naturally cooled to room temperature, the cooled high-entropy alloy sample is taken out of the directional solidification furnace and the shell is removed by sandblasting or machining to obtain the high-entropy alloy sample (specific sample as shown in the figure). Figure 4 (as shown)

[0090] (2) Place the high-entropy alloy sample in a box-type resistance furnace and keep it at 400℃ for 2 hours to remove residual stress;

[0091] (3) The high-entropy alloy sample is cut along the longitudinal direction. The composition distribution and changes in the bonding area are tested by electron probe microanalysis. The microstructure of the bonding area between the pure metal or alloy and the high-entropy alloy is observed by metallographic microscope, scanning electron microscope and transmission electron microscope. The room temperature and high temperature microhardness of the bonding area are tested, and the tensile properties are tested, so as to accurately screen out the high-entropy alloy composition with excellent performance.

[0092] Example 2

[0093] With nominal components of (FeCoNiCr) 96 The preparation of a high-entropy alloy sample with Al2Ti2 as the main body and a gradient transition region exhibiting coupling of Ni and Ti elements, coupling of Ti and Al elements, and coupling of Ni and Cr elements, with sample dimensions of Φ15mm×120mm, was achieved through the following steps:

[0094] 1. Raw material and shell preparation:

[0095] (1) NiTi, TiAl and NiCr50 master alloy rods are used, with melting points of approximately 1310℃, 1460℃ and 1290℃ respectively. The surface of the rods is machined to a roughness of Ra=3.2μm and the size is Φ14.5mm×60mm.

[0096] (2) According to (FeCoNiCr) 96 The Al2Ti2 high-entropy alloy was prepared from raw materials with the following weight percentages: Fe 24.1%; Co 25.4%; Ni 25.3%; Cr 22.5%; Al 1.0%; Ti 1.7%. It was then melted twice in a vacuum induction melting furnace to ensure the uniformity of the composition and cast into a master alloy ingot with a melting point of approximately 1680℃.

[0097] (3) The rod-shaped ceramic shell for the sample was prepared by investment casting.

[0098] 2. Preparation and composition screening of high-entropy alloy samples:

[0099] The improved Bridgeman directional solidification apparatus was used to efficiently prepare high-entropy alloys with coupled linear gradient change regions of Ni and Ti, Ti and Al, and Ni and Cr elements.

[0100] (1) Assemble the NiTi, TiAl, and NiCr50 intermediate alloy rods onto the bottom of the ceramic mold shell, and fix them together on the stretching rod of the directional solidification furnace; adjust the height of the stretching rod so that 1 / 3 of the pure metal rod is exposed above the liquid surface of the cooling tank, and the rest is completely immersed in the cooling tank. The coolant in the cooling tank is a gallium indium tin alloy (see the schematic diagram for details). Figure 2 (as shown)

[0101] (2) (FeCoNiCr) 96 The Al2Ti2 high-entropy alloy masterbatch is assembled on the upper part of the induction drip coil of the directional solidification furnace (see schematic diagram for details). Figure 2 (as shown)

[0102] (3) Turn on the vacuum pump of the directional solidification furnace to achieve a vacuum level of 10 in the equipment. -1 Pa;

[0103] (4) Set the furnace temperature to 1720℃, turn on the heating power of the directional solidification furnace to raise the temperature of the upper and lower heating bodies in the furnace at a rate of 15℃ / min, and keep it at the temperature for 25 minutes after reaching the temperature to ensure that the ceramic shell is fully preheated. At the same time, the part of the alloy rod exposed in the middle of the bottom of the shell melts.

[0104] (5) Turn on the induction drip system and adjust the power of the induction coil to 35kW (FeCoNiCr) 96 The Al2Ti2 high-entropy alloy master alloy ingot is rotated at a speed of 10 rad / min and fed at a rate of 0.4 mm / s until a sufficient amount of high-entropy alloy is melted, at which point the induction dripping system is shut off.

[0105] (6) After the high-entropy alloy is dripped, keep it at a temperature for 30 minutes to allow the melt in the bonding zone of the intermediate alloy and the high-entropy alloy to mix and diffuse, forming an element coupling gradient transition zone.

[0106] (7) Turn off the heating power of the directional solidification furnace to allow the alloy melt inside the shell to cool and solidify naturally, thereby completing the efficient preparation of high-entropy alloys with Ni and Ti elements, Ti and Al elements, and Ni and Cr elements coupled linear gradient change regions.

[0107] 3. Ingredient screening:

[0108] (1) After the temperature inside the furnace has cooled naturally to room temperature, the cooled high-entropy alloy sample is taken out from the directional solidification furnace and the shell is removed by sandblasting or machining to obtain the high-entropy alloy sample.

[0109] (2) Place the high-entropy alloy sample in a box-type resistance furnace and keep it at 650℃ for 4 hours to remove residual stress;

[0110] (3) The high-entropy alloy sample is cut along the longitudinal direction. The composition distribution and changes in the bonding area are tested by electron probe microanalysis. The microstructure of the bonding area between the pure metal or alloy and the high-entropy alloy is observed by metallographic microscope, scanning electron microscope and transmission electron microscope. The room temperature and high temperature microhardness of the bonding area are tested, and the tensile properties are tested, so as to accurately screen out the high-entropy alloy composition with excellent performance.

[0111] like Figure 5 As shown, Figure 5This is a micrograph of the bonding region of a high-entropy alloy cylindrical sample with a linear gradient change region of Ti and Al elements, prepared in this embodiment, after being cut open. Figure 5 It can be seen that the tissue in the binding zone exhibits a uniform gradient change.

[0112] like Figure 6 As shown, Figure 6 The right image shows the elemental line scan spectrum of the bonding region after sectioning a cylindrical high-entropy alloy sample with a linear gradient variation region of Ti and Al elements prepared in this embodiment. Figure 6 It can be seen that the elements in the binding region exhibit uniform gradient changes.

[0113] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0114] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for designing high-throughput, high-entropy alloy compositions, comprising the following steps: S1) Prepare an initial sample of a pure metal or alloy; the elements of the pure metal or alloy are selected from one or two of Fe, Co, Ni, Al, Ti, Cu, Si, Ta, Nb, Cr, Zr, V, Mo, Hf, C, and B. S2) The raw materials are prepared according to the high-entropy alloy composition and then a master alloy ingot is prepared; the master alloy ingot is prepared from at least three elements selected from Fe, Co, Ni, Al, Ti, Cu, Si, Ta, Nb, Cr, Zr, V, Mo, Hf, C, and B; S3) The initial sample is assembled at the bottom of the shell, the shell is fixed on the directional solidification furnace pull-out device, and the position of the shell is adjusted so that a part of the initial sample is exposed above the liquid surface of the cooling tank, and the rest is immersed in the cooling liquid of the cooling tank; the initial sample in the shell can be a sample of the same type or a sample of different types. S4) Assemble the master alloy ingot on the upper part of the induction dripping system of the directional solidification furnace, and turn on the heating power supply of the directional solidification furnace to make the temperature higher than the melting point of the initial sample and the melting point of the master alloy ingot. S5) Turn on the induction dripping system until the master alloy ingot melts and drips into the mold shell. After heat preservation, the initial sample and the melt of the master alloy ingot form a gradient transition zone, and then cool and solidify.

2. The method according to claim 1, characterized in that, The shell is a ceramic shell, which is prepared by investment casting.

3. The method according to claim 1, characterized in that, The height of the initial sample exposed above the liquid surface in the cooling tank is 1 / 4 to 1 / 2 of the initial sample, and the coolant is a gallium indium tin alloy.

4. The method according to claim 1, characterized in that, The directional solidification furnace is maintained under vacuum or purged with inert gas, wherein the vacuum level is 3 × 10⁻⁶. -3 ~9×10 -1 Pa.

5. The method according to claim 1, characterized in that, The temperature of the directional solidification furnace is 50-100°C above the melting point of the initial sample and the melting point of the master alloy ingot.

6. The method according to claim 1, characterized in that, In step S4), the heating rate of the directional solidification furnace is 10~15℃ / min, and the holding time after reaching the set temperature is 20~40min.

7. The method according to claim 1, characterized in that, In step S5), the power of the induction coil of the induction dripping system is 30~40kW, the rotation speed of the master alloy ingot is 5~10rad / min, the feed rate is 0.3~0.5mm / s, and the heat preservation time is 0~30min.

8. The method according to claim 1, characterized in that, The cooling and solidification specifically refers to: The pulling device is activated at a moving speed of 0.001~20mm / s, and the shell moves vertically from top to bottom into the cooling tank; Alternatively, turn off the heating power of the directional solidification furnace to allow the alloy melt inside the mold to cool and solidify naturally.

9. The method according to any one of claims 1 to 8, characterized in that, Step S5) is followed by: The solidified high-entropy alloy sample was removed and then subjected to stress-relief annealing. The high-entropy alloy samples after stress-relief annealing were longitudinally sectioned, and the composition, microstructure and mechanical properties of the bonding zone were analyzed to screen out high-entropy alloy components with excellent performance.

10. The method according to claim 9, characterized in that, The stress-relief annealing temperature is 300~900℃, and the holding time is 1~4h.

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