Low-cost iron-based high-toughness multi-principal-element alloy and preparation method thereof

Abstract

The invention discloses a low-cost iron-based high-toughness multi-principal-element alloy and a preparation method thereof, and belongs to the technical field of novel metal materials and preparation thereof. The method comprises the following steps that raw materials are proportioned and cleaned according to the mass percent of composition elements contained in the low-cost iron-based high-toughness multi-principal-element alloy; alloy smelting is conducted through a non-self-consumption vacuum arc furnace, and casting forming is conducted through a water-cooling copper mold; the obtained as-cast multi-principal-element alloy is subjected to component homogenization heat treatment in the argon protection atmosphere; and cold rolling deformation and subsequent aging heat treatment are combined to obtain the low-cost iron-based high-toughness multi-principal-element alloy disclosed by the invention. The multi-principal-element alloy takes the Fe element as a matrix and does not contain common expensive Co and other elements in the multi-principal-element alloy, the preparation method is simple, only vacuum arc melting and cold rolling deformation treatment are included, and the multi-principal-element alloy with good obdurability matching can be obtained by combining subsequent simple and convenient aging heat treatment. According to the multi-principal-element alloy subjected to aging treatment for 30 minutes, the yield strength reaches 1102.3 MPa, the ultimate tensile strength reaches 1313.5 MPa, the ductility is 23.5%, and good obdurability matching is shown.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel metal materials and their preparation, and particularly relates to a low-cost iron-based high-strength and high-toughness multi-principal element alloy and a preparation method thereof. Background Art

[0002] With the diversification of industrial demands and the continuous pursuit of high-performance materials, high-strength and high-toughness alloy materials are increasingly widely used in fields such as aerospace, automotive, energy, and structural materials. However, traditional high-strength alloys often face problems such as high cost, limited resources, and difficult processing, which limit their widespread application. To overcome these limitations, low-cost, high-strength and high-toughness alloy materials have gradually become a research hotspot.

[0003] As an important engineering material, iron-based alloys have rich resources, low production costs, and good mechanical properties, so they are widely used in many fields. Traditional iron-based alloys, such as carbon steel and alloy steel, have certain deficiencies in high-temperature strength, toughness, and corrosion resistance. In order to improve the comprehensive properties of these alloys, multi-principal element alloys have received increasing attention as a new type of material in recent years. Through the diversified design of alloying elements, multi-principal element alloys can optimize the properties of alloys without relying on a single main alloying element. Although multi-principal element alloys have excellent properties, due to the inclusion of multiple alloying elements, especially the addition of some high-cost metal elements (such as Co element, etc.), the production cost will be relatively high. Therefore, the research on multi-principal element alloys still faces some challenges, especially in maintaining low production costs while improving the strength and toughness of alloys. Reasonably controlling the cost of multi-principal element alloys while ensuring excellent mechanical properties and reliability of materials is still a technical problem to be solved urgently. Summary of the Invention

[0004] To solve the above technical problems, the present invention proposes a low-cost iron-based high-strength and high-toughness multi-principal element alloy. Through simple cold rolling deformation and aging heat treatment, good strength-toughness matching can be obtained.

[0005] The present invention proposes a low-cost iron-based high-strength and high-toughness multi-principal element alloy. Through reasonable element ratio and aging heat treatment, its strength and toughness can be significantly improved, and while ensuring the material properties, the production cost of the alloy can be reduced. The development of this alloy is expected to provide an economical and efficient solution for the application of high-performance structural materials, especially suitable for aerospace, automotive manufacturing, and other high-load working environments.

[0006] To achieve the above object, the present invention provides a low-cost iron-based high-strength and high-toughness multi-principal element alloy. The composition element ranges of the low-cost iron-based high-strength and high-toughness multi-principal element alloy are, by mass percentage, Fe: 45-48%, Ni: 34-38%, Cr: 9-13%, Al: 2-3%, Ti: 2-3%.

[0007] Further, the composition elements of the low-cost iron-based high-strength and high-toughness multi-principal element alloy of the present invention are, by mass percentage, Fe: 47.91%, Ni: 37.50%, Cr: 9.49%, Al: 2.47%, Ti: 2.63%.

[0008] The present invention also provides a preparation and heat treatment method for the low-cost iron-based high-strength and high-toughness multi-principal element alloy, which specifically includes the following steps:

[0009] (1) Weigh the elements according to the mass percentages of the element composition of the multi-principal element alloy described in the claims, and then clean the elements.

[0010] (2) Use a non-consumable vacuum arc furnace to melt the multi-principal element alloy. After the melting is completed, use a mold to cast the alloy into shape to obtain a multi-principal element alloy ingot.

[0011] (3) Perform homogenization heat treatment on the as-cast multi-principal element alloy in step (2), then perform cold rolling deformation, and then combine with further aging heat treatment to obtain the low-cost iron-based high-strength and high-toughness multi-principal element alloy of the present invention.

[0012] Further, in step (1), the metal raw materials used are Fe, Cr, Ni, Al, and Ti particles with a mass fraction greater than 99.99%. Use absolute ethanol and an ultrasonic cleaner to clean the proportioned metal raw materials, and dry them with cold air for standby.

[0013] Further, the specific process of the non-consumable vacuum arc furnace melting in step (2) is as follows:

[0014] First, according to the melting points of the composition elements of the multi-principal element alloy, place the obtained metal particles in a copper crucible in ascending order of melting point, and close the furnace door of the arc furnace. Use a vacuum mechanical pump and a vacuum molecular pump in sequence to pump the pressure in the furnace cavity to less than 5×10 -4 Pa. After the vacuum pumping is completed, introduce high-purity argon gas into the furnace cavity, and repeat the vacuum pumping three times to achieve the purpose of gas washing and exhaust the oxygen in the furnace cavity. After the gas washing is completed, introduce high-purity argon gas into the furnace cavity again to make the pressure in the furnace cavity -0.05 MPa.

[0015] Then, a tungsten electrode is used to repeatedly melt the titanium balls in the copper crucible in the furnace chamber, and the color change after cooling is observed to further determine the cleanliness in the vacuum furnace chamber. After it is determined that the surface of the titanium balls after cooling presents a uniform metallic luster, a tungsten electrode is used to melt the multi-principal element alloy raw materials in the crucible. During the melting process, the temperature and the melting speed of metal particles are controlled by controlling the magnitude of the current. After the multi-principal element alloy is melted and cooled once, a manipulator in the furnace chamber is used to turn over the alloy. Then, repeated melting is carried out, and an electromagnetic force stirring device is used to further promote the full mixing of the multi-principal element alloy components. The melting process is repeated more than seven times.

[0016] Further, the casting and forming process of the multi-principal element alloy described in step (2) is completed using a water-cooled copper mold. After suction casting with the water-cooled copper mold, the size of the multi-principal element alloy ingot is 10×10×80 mm.

[0017] Further, the homogenization heat treatment temperature of the multi-principal element alloy described in step (3) is 1100 °C, the holding time is 4 hours, and the atmosphere is argon protective gas. After the holding is completed, the multi-principal element alloy is cooled to room temperature by water cooling.

[0018] Further, the cold rolling deformation method of the multi-principal element alloy described in step (3) is multi-pass cold rolling, and the rolling direction is the length direction of the multi-principal element alloy ingot. The reduction per pass is controlled to be 0.4 mm. After multi-pass cold rolling deformation, the deformation amount of the multi-principal element alloy ingot in the thickness direction reaches 80%.

[0019] Further, the aging temperature of the multi-principal element alloy described in step (3) is 750 °C, and the holding time is 0.5 - 12 hours. After the holding is completed, the multi-principal element alloy is cooled to room temperature by water cooling.

[0020] The present invention shows the following advantages and technical effects compared with the prior art:

[0021] A low-cost iron-based high-strength and high-toughness multi-principal element alloy involved in the present invention can be obtained by simple vacuum arc furnace melting, and by combining simple cold rolling deformation and aging heat treatment, a good strength-toughness matching can be obtained. Among them, the multi-principal element alloy after 0.5-hour aging treatment shows good mechanical property matching. Specifically, the Fe 47.91 Ni 37.50 Cr 9.49 Al 2.47 Ti 2.63The multi-principal element alloy (by mass percentage), after aging heat treatment, has a phase composition of a simple face-centered cubic structure and an ordered face-centered cubic structure L12 precipitation phase (Ni3Al / Ti). Among them, the multi-principal element alloy after 0.5 hours of aging treatment exhibits excellent strength and toughness matching. Tensile results show that the yield strength of this multi-principal element alloy is 1102.3 MPa, the ultimate tensile strength is 1313.5 MPa, and the elongation is 23.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] To facilitate the understanding of the embodiments of the present invention or the prior art solutions, the drawings involved in the implementation will be briefly described below. Obviously, the drawings described are only a part of the embodiments of the present invention, and based on the knowledge of those of ordinary skill in the art, other possible drawings can be derived without creative labor.

[0023] Figure 1 It is the X-ray diffraction pattern results of the low-cost iron-based high-strength and high-toughness principal element alloy involved in the present invention after different aging heat treatment times;

[0024] Figure 2 It is the room-temperature tensile engineering stress-strain curve of the low-cost iron-based high-strength and high-toughness principal element alloy involved in the present invention after different aging times. DETAILED DESCRIPTION OF THE INVENTION

[0025] Multiple exemplary embodiments of the present invention will be described in detail. Note that these detailed descriptions do not constitute a limitation to the present invention, but should be regarded as a specific description of certain aspects, characteristics, and implementation schemes of the present invention.

[0026] The terms used in the present invention are only for describing specific embodiments and do not limit the present invention. For numerical ranges, it should be understood to cover every intermediate value within that range. Any stated value or intermediate value within the range, including every smaller range within that range, should be regarded as part of the present invention. The upper and lower limits of these smaller ranges can be included or excluded independently.

[0027] Unless otherwise specified, all technical and scientific terms used herein have the meanings commonly understood by those of ordinary skill in the art. Although the present invention describes preferred implementation methods and materials, similar or equivalent methods and materials can also be used as alternatives in actual applications or tests.

[0028] All documents mentioned in this specification are incorporated by reference as describing the methods and / or materials related to the said documents. If there is a conflict with any incorporated document, the content of this specification shall prevail.

[0029] Without departing from the technical scope and spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention, and these changes are obvious to those skilled in the art. Other embodiments derived from the description of the present invention should also be considered as part of the present invention.

[0030] Regarding the words "comprising", "including", "having", "containing", etc., they are all open-ended terms, meaning "including but not limited to".

[0031] The present invention provides a method for preparing and heat-treating a low-cost iron-based high-strength and high-toughness master alloy, and the specific process is as follows:

[0032] Step (1), proportioning and cleaning of the master alloy raw materials: Using an analytical balance with a precision of 0.0001 g, weigh the metal particle raw materials according to the proportion of the master alloy elements involved in the present invention, wherein the mass percentages of the respective constituent elements of the master alloy are Fe: 45 - 48%, Ni: 34 - 38%, Cr: 9 - 13%, Al: 2 - 3%, Ti: 2 - 3%. After the proportioning of each metal element is completed, place it in absolute ethanol and perform ultrasonic cleaning for 20 minutes using an ultrasonic cleaner. After the cleaning is completed, dry the metal raw material particles with the cold air of an air compressor for standby.

[0033] Step (2), cleaning and vacuum pumping treatment of the non-consumable vacuum arc furnace: First, open the furnace door of the arc furnace, and carefully wipe the inside of the furnace cavity of the arc furnace with non-woven fabric and absolute ethanol. First, use copper cleaning solution and non-woven fabric to clean the water-cooled copper crucible, and then use absolute ethanol and non-woven fabric for cleaning. After the arc furnace is cleaned, according to the melting points of the master alloy raw material particles, place the metal particles with lower melting points at the bottom of the copper crucible first, and then sequentially place the metal raw material particles with higher melting points above them. After the titanium ball is polished on the surface with sandpaper and cleaned with absolute ethanol, place it in the center of the copper crucible and close the furnace door of the vacuum furnace. Then perform the vacuum pumping treatment inside the furnace cavity. First, use a vacuum mechanical pump for vacuum pumping operation. After the pressure indication in the furnace cavity is lower than 5 Pa, then use a vacuum molecular pump for vacuum pumping treatment. When the pressure indication in the furnace cavity is lower than 5×10 -4 Pa, it is regarded as a complete vacuum pumping operation. After the vacuum pumping is completed, perform a cyclic gas washing operation. Introduce high-purity argon gas into the furnace cavity. After the pressure indication in the cavity is 0 Pa, repeat the above vacuum pumping operation. After three repeated gas washing operations, complete the vacuum pumping operation before melting. After the vacuum pumping is completed, introduce high-purity argon gas into the furnace cavity until the pressure indication in the furnace cavity is -0.05 MPa.

[0034] Step (3), melting and casting of the high-entropy alloy: First, heat the titanium ball located at the center of the copper crucible with a tungsten electrode tip. After it melts and cools, observe the glossiness of the surface of the titanium ball. Repeat the melting of the titanium ball more than five times. After confirming that the surface of the titanium ball presents a uniform metallic luster, it is considered that the required cleanliness has been achieved in the furnace cavity. Then, use the tungsten electrode tip to heat the high-entropy alloy raw material particles in the crucible. After they melt and cool, use the manipulator in the furnace cavity to turn them over and repeat the smelting more than seven times. During the smelting and heating process, with the help of an electromagnetic force stirring device, further promote the full mixing of the high-entropy alloy components. During the melting process, the current size is controlled within the range of 40 - 200 amperes, and the melting time for each time is controlled at 90 - 120 seconds. After melting, use the manipulator to place the cooled high-entropy alloy button ingot directly above the water-cooled copper mold. Uniformly and fully heat the button ingot with the tungsten electrode tip. When it is observed that the high-entropy alloy button ingot is about to flow, press the suction casting button to complete the casting process of the high-entropy alloy. After casting, the size of the high-entropy alloy ingot is 10×10×80 mm. Wait for 8 - 10 minutes for it to cool sufficiently, and then take out the high-entropy alloy ingot.

[0035] Step (4), homogenization heat treatment of the high-entropy alloy ingot: Place the high-entropy alloy ingot in a quartz tube with a protective atmosphere of high-purity argon and place it in the furnace cavity of the Kejing KSL-1400X-A1 muffle furnace. The heating rate of the muffle furnace is set at 7 °C per minute, the target temperature is 1100 °C, and the holding time is set at 4 hours. After the holding is completed, quickly take out the high-entropy alloy and cool it in water until its temperature drops to room temperature.

[0036] Step (5), cold rolling deformation of the high-entropy alloy: With the help of multi-pass cold rolling deformation treatment, cold roll the high-entropy alloy after homogenization heat treatment. The rolling direction is along the length direction of the high-entropy alloy ingot. During the rolling process, control the deformation amount per pass at 0.4 mm. After multiple passes of repeated rolling, the deformation amount of the high-entropy alloy ingot in the thickness direction reaches 80%.

[0037] Step (6), aging heat treatment of the high-entropy alloy: After cold rolling deformation, place the high-entropy alloy in the Kejing KSL-1400X-A1 muffle furnace for aging heat treatment. The heating rate of the muffle furnace is set at 7 °C per minute, the target temperature is 750 °C, and the holding time is 0.5 - 12 hours. After the holding is completed, quickly take out the high-entropy alloy and cool it in water until its temperature quickly drops to room temperature.

[0038] Example 1

[0039] This example provides a method for preparing Fe 47.91 Ni 37.50 Cr 9.49 Al 2.47Ti 2.63 (by mass percentage), the method for preparing a multi-principal element alloy, in which each constituent element of the multi-principal element alloy is, by mass percentage, Fe: 47.91%, Ni: 37.50%, Cr: 9.49%, Al: 2.47%, Ti: 2.63%. The specific preparation process is as follows:

[0040] Step (1), proportioning and cleaning of the multi-principal element alloy raw materials: Using a Lichen analytical balance with a precision of 0.0001 g, the metal particle raw materials are weighted according to the proportion of the multi-principal element alloy elements in this embodiment, where the mass percentages of each constituent element of the multi-principal element alloy are Fe: 47.91%, Ni: 37.50%, Cr: 9.49%, Al: 2.47%, Ti: 2.63%. After the proportioning of each metal element is completed, it is placed in absolute ethanol, and ultrasonic cleaning is carried out for 20 minutes using an ultrasonic cleaner. After the cleaning is completed, the metal raw material particles are dried with the cold air of an air compressor and reserved for use.

[0041] Step (2), cleaning and vacuum pumping treatment of the non-consumable vacuum arc furnace: First, open the furnace door of the arc furnace, and carefully wipe the inside of the furnace cavity of the arc furnace with non-woven fabric and absolute ethanol. The water-cooled copper crucible is first cleaned with copper cleaning solution and non-woven fabric, and then cleaned with absolute ethanol and non-woven fabric. After the arc furnace is cleaned, according to the melting points of the multi-principal element alloy raw material particles, the metal particles with lower melting points are first placed at the bottom of the copper crucible, and then the metal raw material particles with higher melting points are placed above them in turn. After the titanium balls are polished on the surface with sandpaper and cleaned with absolute ethanol, they are placed in the center of the copper crucible and the vacuum furnace door is closed. Then, the vacuum pumping treatment inside the furnace cavity is carried out. First, use a vacuum mechanical pump for vacuum pumping operation. After the pressure indication in the furnace cavity is lower than 5 Pa, then use a vacuum molecular pump for vacuum pumping treatment. When the pressure indication in the furnace cavity is lower than 5×10 -4 Pa, it is regarded as a complete vacuum pumping operation. After the vacuum pumping is completed, a cyclic gas washing operation is carried out. High-purity argon gas is introduced into the furnace cavity. After the pressure indication in the cavity is 0 Pa, repeat the above vacuum pumping operation. After three repeated gas washing operations, the vacuum pumping operation before melting is completed. After the vacuum pumping is completed, high-purity argon gas is introduced into the furnace cavity until the pressure indication in the furnace cavity is -0.05 MPa.

[0042] Step (3), melting and casting of the multi-principal element alloy: First, heat the titanium ball located at the center of the copper crucible through the tungsten electrode tip. After it melts and cools, observe the glossiness of the surface of the titanium ball. Repeat melting the titanium ball more than five times. After confirming that the surface of the titanium ball presents a uniform metallic luster, it is considered that the required cleanliness has been achieved in the furnace cavity. Then, use the tungsten electrode tip to heat the multi-principal element alloy raw material particles in the crucible. After it melts and cools, use the manipulator in the furnace cavity to turn it over and repeat the smelting more than seven times. During the smelting and heating process, with the help of the electromagnetic force stirring device, further promote the full mixing of the multi-principal element alloy components. During the melting process, the current size control range is 40 - 200 amperes, and the melting time for each time is controlled to be 90 - 120 seconds. After melting is completed, use the manipulator to place the cooled multi-principal element alloy button ingot directly above the water-cooled copper mold. Uniformly and fully heat the button ingot through the tungsten electrode tip. When it is observed that the multi-principal element alloy button ingot is about to flow, press the suction casting button to complete the casting process of the multi-principal element alloy. After casting, the size of the multi-principal element alloy ingot is 10×10×80 mm. Wait for 8 - 10 minutes for it to cool sufficiently, and then take out the multi-principal element alloy ingot.

[0043] Step (4), homogenization heat treatment of the multi-principal element alloy ingot: Place the multi-principal element alloy ingot in a quartz tube with a protective atmosphere of high-purity argon and place it in the furnace cavity of the Kejing KSL-1400X-A1 muffle furnace. Set the heating rate of the muffle furnace to 7 °C / minute, the target temperature to 1100 °C, and the holding time to 4 hours. After the holding is completed, quickly take out the multi-principal element alloy and place it in water for cooling until its temperature drops to room temperature.

[0044] Step (5), cold rolling deformation of the multi-principal element alloy: With the help of multi-pass cold rolling deformation treatment, perform cold rolling deformation on the multi-principal element alloy after homogenization heat treatment. The rolling direction is along the length direction of the multi-principal element alloy ingot. During the rolling process, control the deformation amount per pass to be 0.4 mm. After multiple passes of repeated rolling, the deformation amount of the multi-principal element alloy ingot along the thickness direction reaches 80%.

[0045] Step (6), aging heat treatment of the multi-principal element alloy: After cold rolling deformation, place the multi-principal element alloy in the Kejing KSL-1400X-A1 muffle furnace for aging heat treatment. Set the heating rate of the muffle furnace to 7 °C / minute, the target temperature to 750 °C, and the holding time to 0.5 hour. After the holding is completed, quickly take out the multi-principal element alloy and place it in water for cooling until its temperature quickly drops to room temperature.

[0046] Example 2

[0047] This example is different from Example 1 only in the holding time in Step (6), and this holding time is set to 2 hours.

[0048] Example 3

[0049] This embodiment is different from Embodiment 1 only in the heat preservation time in step (6), and the heat preservation time is set to 4 hours.

[0050] Embodiment 4

[0051] This embodiment is different from Embodiment 1 only in the heat preservation time in step (6), and the heat preservation time is set to 12 hours.

[0052] Experimental Example

[0053] The above-mentioned Embodiments 1-4 of the present invention are subjected to relevant characterization and analysis, and the specific methods and results are as follows:

[0054] (1) Test method

[0055] X-ray diffraction (XRD) test: The experiment was carried out using a Rigaku SmartLab diffractometer in Japan. The current and voltage during the test were set to 40 kV and 150 mA respectively, and the diffraction angle (2θ) range was 20° to 100°. Before the test, the surface of the high-entropy alloy was polished successively with sandpapers of 400# to 2000#, and then ultrasonically cleaned with absolute ethanol to obtain a clean test surface for standby. The diffraction data obtained from the test was analyzed and calibrated by Jade 9 software.

[0056] Room temperature uniaxial tensile test: The uniaxial tensile test was carried out using an MTS E43.504 electronic universal testing machine, where the test temperature was room temperature and the tensile rate was 1×10 -4 s -1 . The total length of the high-entropy alloy sample used for the tensile test was 40 mm, the width of the parallel gauge was 2 mm, and the length was 10 mm. The strain during the tensile process was measured by an extensometer. Before the test, the tensile sample was polished successively with sandpapers of 240 mesh to 2000 mesh to ensure the same surface state of the tensile sample.

[0057] (2) Test results

[0058] Figure 1 The X-ray diffraction results of the Fe 47.91 Ni 37.50 Cr 9.49 Al 2.47 Ti 2.63 (mass percentage) high-entropy alloy after aging heat treatment for 0.5 hours, 2 hours, 4 hours, and 12 hours (Embodiments 1-4) are shown. It can be seen that the high-entropy alloys in Embodiments 1-4 are all face-centered cubic structures and contain an ordered L12 face-centered cubic structure.

[0059] Figure 2Shown are the room-temperature engineering stress-strain curves of the Fe 47.91 Ni 37.50 Cr 9.49 Al 2.47 Ti 2.63 (mass percentage) multi-principal element alloys. The yield strength, tensile strength, and elongation in each example are shown in Table 1. It can be seen that the multi-principal element alloys after different aging heat treatments exhibit different strength and toughness matches. Specifically, after aging for 0.5 hours (Example 1), the yield strength is 1102.3 MPa, the tensile strength is 1313.5 MPa, and the elongation is 23.5%. After aging for 2 hours (Example 2), the yield strength is 1041.7 MPa, the tensile strength is 1277.1 MPa, and the elongation is 22.6%. After aging for 4 hours (Example 3), the yield strength is 1040.4 MPa, the tensile strength is 1242.9 MPa, and the elongation is 18.3%. After aging for 12 hours (Example 4), the yield strength is 951.2 MPa, the tensile strength is 1166.6 MPa, and the elongation is 15.3%

[0060] Table 1 Room-temperature tensile property parameters of Examples 1, 2, 3, and 4 in the present invention

[0061]

[0062] In summary, a kind of Fe 47.91 Ni 37.50 Cr 9.49 Al 2.47 Ti 2.63 (mass percentage) multi-principal element alloy, after aging for 0.5 hours in the preparation process (6), exhibits a good strength and toughness match, where the yield strength is 1102.3 MPa, the tensile strength is 1313.5 MPa, and the elongation is 23.5%.

[0063] The above examples are only the preferred solutions of the present invention and do not limit the technical scope of the present invention. Without departing from the design concept of the present invention, those skilled in the art can make various deformations and improvements to the technical solutions of the present invention, and these deformations and improvements should be included in the protection scope determined by the claims of the present invention.

Claims

1. A low-cost iron-based high-strength and high-toughness multi-principal element alloy, characterized in that, The composition elements of the multi-principal element alloy have the following mass percentage ranges: Fe: 45-48%, Ni: 34-38%, Cr: 9-13%, Al: 2-3%, Ti: 2-3%.

2. A low-cost iron-based high-strength and tough multi-principal element alloy according to claim 1, characterized in that, The mass percentages of the composition elements of the multi-principal element alloy are respectively: Fe: 47.91%, Ni: 37.50%, Cr: 9.49%, Al: 2.47%, Ti: 2.63%.

3. A low-cost iron-based high-strength and tough multi-principal element alloy according to claim 1, characterized in that The phase composition of the multi-principal element alloy is a simple face-centered cubic structure and an ordered face-centered cubic structure L12 precipitation phase Ni3Al / Ti.

4. The preparation method of a low-cost iron-based high-strength and tough multi-principal element alloy according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: (1) According to the mass percentages of the composition elements of the low-cost iron-based high-strength and high-toughness multi-principal element alloy, mix and clean the metal particle raw materials; (2) Melting the cleaned metal particles by a non-consumable vacuum arc furnace and casting them into shape using a water-cooled copper mold; (3) Performing homogenization heat treatment on the as-cast multi-principal element alloy obtained in step (2) in an argon protection atmosphere; the homogenization heat treatment temperature is 1000-1200 °C, and the holding time is 0.5-12 hours; (4) Performing multi-pass cold rolling deformation on the homogenization heat-treated multi-principal element alloy at room temperature; (5) Performing aging annealing heat treatment on the multi-principal element alloy obtained after cold rolling deformation to obtain a low-cost iron-based high-strength and high-toughness multi-principal element alloy.

5. The preparation method of the multi-principal element alloy according to claim 4, characterized in that, In step (1), the metal particles are Fe, Ni, Cr, Al, and Ti metal particles with a mass fraction greater than 99.99%; the cleaning of the metal particles uses an anhydrous ethanol solution and an ultrasonic cleaner.

6. The preparation method of the multi-principal element alloy according to claim 4, characterized in that, In step (2), the WK-II type non-consumable vacuum arc furnace is used for the melting process, and the specific melting steps are as follows: (a)Place the proportioned and cleaned metal particles in the copper crucible of the arc furnace in sequence according to the melting point from low to high; close the furnace door of the arc furnace and extract the air pressure in the furnace cavity to be lower than 5×10 -4 Pa; then introduce high-purity argon into the furnace cavity, and then perform a vacuum pumping treatment; after the vacuum pumping step is completed, introduce high-purity argon into the furnace cavity again to make the pressure in the furnace cavity -0.05 MPa; (b) After determining that the cleanliness of the furnace cavity meets the requirements, heat the placed metal particles by the arc of the tungsten electrode head for melting; during the melting process, the current is controlled within the range of 40-200 A.

7. The preparation method of the multi-principal element alloy according to claim 4, characterized in that, In step (2), the size of the multi-principal element alloy obtained by water-cooled copper mold casting is 10×10×80 mm.

8. The preparation method of the multi-principal element alloy according to claim 4, characterized in that In step (3), the homogenization heat treatment temperature is 1100 °C, and the holding time is 4 hours.

9. The preparation method of the multi-principal element alloy according to claim 4, characterized in that In step (4), for the multi-pass cold rolling deformation, the reduction per pass is 0.4 mm; after multi-pass repeated rolling, the total rolling deformation is 80% of the original thickness.

10. The preparation method of the multi-principal element alloy according to claim 4, wherein, In step (5), the aging heat treatment temperature is 750 °C, and the holding time is 0.5-12 hours.

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