Method for enabling FeMnCoCr series metastable state high-entropy alloy to generate martensite reversal transformation

Abstract

The invention provides a method for performing martensite reversal transformation on a FeMnCoCr-series metastable-state high-entropy alloy, which comprises the following steps of: S1, determining the mass of Fe, Co and Cr elementary substance particles and a FeMn alloy block according to the molar ratio of alloy elements, uniformly mixing, smelting and casting to obtain a FeMnCoCr-series alloy molded part; s2, the alloy forming part is subjected to annealing, and the FeMnCoCr series metastable state high-entropy alloy is obtained; s3, the FeMnCoCr system metastable state high-entropy alloy is cut into strips, and stretching treatment is carried out on the FeMnCoCr system metastable state high-entropy alloy; and S4, the stretched FeMnCoCr series metastable state high-entropy alloy is subjected to ultrasonic treatment. The method disclosed by the invention is simple in process, high in repeatability, short in treatment time and high in martensite reverse transformation efficiency; and the ultrasonic treatment time can be regulated and controlled, so that the reverse transformation degree of the martensite can be flexibly regulated and controlled as required. Compared with martensite reversal transformation achieved through traditional heat treatment, the method does not need heating, energy consumption is low, and the method has wide application prospects in the field of energy absorption protection structural parts.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, and in particular to a method for inducing martensitic reversal transformation in FeMnCoCr metastable high-entropy alloys. Background Technology

[0002] High-entropy alloys, also known as multi-principal-element alloys, are composed of multiple elements in equiatomic or near-equiatomic ratios. Compared to traditional alloys, high-entropy alloys exhibit superior properties unmatched by traditional alloys, such as high hardness, high strength, high toughness, and excellent corrosion resistance, due to their multi-principal-element design concept and unique high-entropy effect.

[0003] Metastable high-entropy alloys are a new type of alloy that has emerged recently. Unlike traditional single-phase alloys, the addition of unstable elements to the alloy system causes a series of phase transformations after being subjected to external forces, thus affecting the mechanical properties of the alloy. Compared with other alloys, the persistent and stable strain distribution and excellent work hardening ability of FeMnCoCr metastable high-entropy alloys make them promising for energy-absorbing protective structures. However, to save costs, energy-absorbing protective structures often need to be reused. Therefore, FeMnCoCr metastable high-entropy alloys need to be treated to achieve alloy recovery for reuse. However, this recovery requires prolonged high-temperature heating, resulting in high energy consumption and hindering carbon neutralization.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a novel and efficient method for inducing martensitic reversal in FeMnCoCr metastable high-entropy alloys. This method requires no heating, has high repeatability, and is time-efficient, energy-saving, and environmentally friendly.

[0006] This invention provides a method for inducing martensitic reversal transformation in FeMnCoCr metastable high-entropy alloys, comprising the following steps:

[0007] Step S1: Determine the mass of Fe, Co, and Cr elemental particles and FeMn alloy blocks according to the molar ratio of alloying elements, mix them evenly, and then melt and cast to obtain FeMnCoCr alloy molded parts; Mn is extremely volatile during the melting process, so using FeMn alloy blocks can reduce the volatilization of Mn during melting.

[0008] Step S2: Anneal the alloy forming part to obtain the FeMnCoCr metastable high-entropy alloy;

[0009] Step S3: Cut the FeMnCoCr metastable high-entropy alloy into strips and perform stretching treatment;

[0010] Step S4: The stretched FeMnCoCr metastable high-entropy alloy is subjected to ultrasonic treatment.

[0011] FeMnCoCr metastable high-entropy alloys, such as Fe 50 Mn 30 Co 10 Cr 10 Metastable high-entropy alloys consist of a face-centered cubic (FCC) γ phase and a hexagonal close-packed (HCP) ε phase. During deformation, a stress-induced transformation occurs from the FCC phase to the HCP phase, known as a martensitic transformation. During deformation, the internal FCC austenite phase transforms into a hexagonal close-packed martensite phase under stress. This transformation alleviates localized stress concentration, allowing for stress redistribution during deformation and effectively delaying necking, resulting in good plasticity. Simultaneously, the formation of a new martensite phase significantly enhances the material's strength; this process is called transformation-induced plasticity (TRIP). This effect makes FeMnCoCr metastable high-entropy alloys, such as Fe... 50 Mn 30 Co 10 Cr 10 Metastable high-entropy alloys exhibit excellent mechanical properties at room temperature, including an ultimate tensile strength of 850 MPa and an elongation of 60%. Compared to other alloys, the persistently stable strain distribution and excellent work hardening ability make FeMnCoCr metastable high-entropy alloys promising candidates for energy-absorbing protective structural components.

[0012] To save costs, energy-absorbing protective structures are often reused, for example in Fe... 50 Mn 30 Co 10 Cr 10 After metastable high-entropy alloys absorb energy and undergo martensitic transformation, Fe is often restored through post-treatment methods such as annealing. 50 Mn 30 Co 10 Cr 10 The martensitic reversal transformation from the HCP phase to the FCC phase in metastable high-entropy alloys allows for alloy recovery and reuse. However, this recovery requires prolonged high-temperature heating, resulting in high energy consumption and hindering carbon neutralization.

[0013] Therefore, this invention proposes a novel and efficient method for inducing martensitic reversal in metastable high-entropy alloys. This method involves melting and casting a FeMnCoCr-based metastable high-entropy alloy, followed by homogenization annealing and pre-stretching deformation to induce a martensitic transformation from a face-centered cubic (FCC) phase to a hexagonal close-packed (HCP) phase. Subsequently, the metastable high-entropy alloy can be treated using, for example, ultrasonic-assisted forming technology, to achieve the martensitic reversal from the HCP phase to the FCC phase.

[0014] Compared to traditional heat treatment for martensitic reversal, the method of this invention requires no heating, is simple in process, highly repeatable, has a short processing time, low energy consumption, and is energy-saving and environmentally friendly, while also achieving high efficiency in martensitic reversal. Furthermore, the ultrasonic treatment time in this method is adjustable, allowing for flexible control of the degree of martensitic reversal as needed. Therefore, the method of this invention for inducing martensitic reversal in metastable high-entropy alloys has broad application prospects in the field of energy-absorbing protective structures.

[0015] According to some embodiments, the composition of the FeMnCoCr metastable high-entropy alloy is calculated by molar ratio as follows: Fe: 40% to 60%, for example 42%, 45%, 48%, 51%, 55%, 59%, etc.; Mn: 20% to 40%, for example 23%, 26%, 29%, 33%, 36%, 39%, etc.; Co: 5% to 15%, for example 7%, 9%, 11%, 13%, 14.5%, etc.; Cr: 5% to 15%, for example 7%, 9.5%, 11%, 13.5%, 14.5%, etc.

[0016] Preferably, the composition of the FeMnCoCr metastable high-entropy alloy is calculated by molar ratio as follows: Fe: 45% to 55%, Mn: 25% to 35%, Co: 5% to 15%, Cr: 5% to 15%. FeMnCoCr metastable high-entropy alloys within the above-mentioned proportion range can achieve better conversion and higher conversion efficiency.

[0017] More preferably, the composition of the FeMnCoCr metastable high-entropy alloy is calculated by molar ratio as follows: Fe: 50%, Mn: 30%, Co: 10%, Cr: 10%. The FeMnCoCr metastable high-entropy alloy with this ratio can achieve a very good degree of conversion and a higher conversion efficiency.

[0018] To reduce the volatilization of Mn during the smelting process, according to some embodiments, the mass ratio of Fe to Mn in the FeMn alloy block in step S1 is 1:0.5 to 1:2, for example, 1:0.75, 1:0.9, 1:1.1, etc., preferably 1:1. This mass ratio of Fe to Mn can minimize the volatilization of Mn during the smelting process.

[0019] Preferably, the purity of the Fe, Co, Cr elemental particles and the FeMn alloy block is 99.5% or higher, more preferably 99.9% or higher. The higher the purity of the Fe, Co, Cr elemental particles and the FeMn alloy block, the closer the actual molar ratio of the smelted alloy will be to the calculated molar ratio.

[0020] According to some embodiments, the melting in step S1 is carried out in a vacuum induction melting furnace. Specifically, the uniformly mixed alloy elements are melted in an inert gas atmosphere, and the resulting molten metal is then cast into a water-cooled copper mold to obtain a FeMnCoCr alloy molded part. The inert gas can be argon, helium, etc.

[0021] According to some embodiments, when melting is carried out in a vacuum induction melting furnace, the FeMn alloy block is placed at the bottom of the vacuum induction melting furnace to reduce the volatilization of Mn.

[0022] To achieve a more uniform distribution of alloying elements and reduce element segregation, according to some embodiments, the annealing conditions in step S2 are annealing at 1000°C to 1500°C for 1 to 3 hours, such as annealing at 1200°C for 2.6 hours, annealing at 1350°C for 2 hours, annealing at 1400°C for 1.6 hours, annealing at 1460°C for 1.3 hours, etc., preferably annealing at 1100°C to 1300°C for 1.5 to 2.5 hours, in order to achieve a more uniform element distribution and less element segregation.

[0023] According to some embodiments, the tensile deformation amount in step S3 is 45% to 75% of the elongation at break, for example, 48%, 52%, 55%, 59%, 65%, 69%, 74%, etc., preferably 50% to 70%. In actual energy-absorbing structural applications, the alloy may undergo varying degrees of deformation and martensitic phase transformation. Different tensile deformation amounts can be set according to various deformation conditions during actual applications.

[0024] According to some embodiments, the ultrasonic treatment in step S4 employs ultrasonic-assisted shaping technology.

[0025] According to some embodiments, the frequency of the ultrasonic vibration in the ultrasonic treatment described in step S4 is 2.0 × 10⁻⁶. 4 Hz to 2.0×10 12 Hz, for example, 5.0 × 104 Hz, 2.0×10 5 Hz, 5.0×10 7 Hz, 2.0×10 9 Hz, 7.0×10 11 The ultrasonic frequency is Hz, and the load pressure is 700N to 1300N, such as 750N, 800N, 840N, 890N, 930N, 980N, 1050N, 1200N, 1250N, etc. The ultrasonic time is 0min to 50min, excluding 0min, such as 3min, 7min, 10min, 15min, 20min, 26min, 31min, 38min, 45min, 49min, etc.

[0026] Preferably, the frequency of the ultrasonic vibration is 2.0 × 10⁻⁶. 4 Hz to 10 12 The Hz, the load pressure is 900N to 1100N, and the ultrasonic time is 5min to 40min.

[0027] The method of the present invention for inducing martensitic reversal transformation in metastable high-entropy alloys involves preparing a cast FeMnCoCr metastable high-entropy alloy by melting and annealing it, then subjecting the FeMnCoCr metastable high-entropy alloy to pre-stretch deformation treatment to induce stress-induced martensitic transformation (FCC phase to HCP phase), and then, for example, using an ultrasonic-assisted forming device, ultrasonically treating the metastable high-entropy alloy to induce martensitic reversal transformation (HCP phase to FCC phase).

[0028] The method for achieving martensitic reversal in this invention is simple, has a short processing time, and high repeatability. Furthermore, the degree of martensitic reversal can be flexibly adjusted according to application requirements. This ultrasonic-assisted forming method provides a new approach to the martensitic reversal of metastable high-entropy alloys. Moreover, this method is energy-efficient, highly effective, and allows for controllable reversal, eliminating the need for prolonged heating and significant carbon emissions associated with traditional heat treatment. Therefore, it has broad application prospects in the field of energy-absorbing protective structures and possesses significant engineering application value. Attached Figure Description

[0029] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1A flowchart of a method for inducing martensitic reversal transformation in a metastable high-entropy alloy according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of an ultrasonic-assisted shaping apparatus according to an embodiment of the present invention;

[0032] Figure 3 For the Fe of Comparative Example 1 of the present invention 50 Mn 30 Co 10 Cr 10 Phase distribution diagram of the original state of the metastable high-entropy alloy (i.e., after 0 min of ultrasonic treatment);

[0033] Figure 4 Fe according to Embodiment 1 of the present invention 50 Mn 30 Co 10 Cr 10 Phase distribution diagram of a metastable high-entropy alloy after 10 min of ultrasonic treatment;

[0034] Figure 5 Fe according to Embodiment 2 of the present invention 50 Mn 30 Co 10 Cr 10 Phase distribution diagram of a metastable high-entropy alloy after 20 min of ultrasonic treatment in its original state;

[0035] Figure 6 Fe according to Embodiment 3 of the present invention 50 Mn 30 Co 10 Cr 10 Phase distribution diagram of a metastable high-entropy alloy after 30 min of ultrasonic treatment in its original state;

[0036] Explanation of reference numerals in the attached figures:

[0037] 10: First support; 20: Transducer; 30: Amplitude bar; 40: Second support; 50: Tool head; 60: Sample; 70: Base; 80: First limiting block; 81: Second limiting block; 90: Ultrasonic power supply. Detailed Implementation

[0038] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form includes the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] It should be noted that if the text uses terms such as "first" or "second", these terms are only used to distinguish similar objects and should not be interpreted as indicating or implying their relative importance, order of precedence, or implicitly indicating the number of technical features indicated. It should be understood that the data in the descriptions of "first" and "second" can be interchanged where appropriate.

[0041] Throughout the accompanying drawings, identical elements are represented by the same or similar reference numerals. Conventional structures or configurations may be omitted where they might cause confusion in understanding the invention. Furthermore, the shapes, dimensions, and positional relationships of the components in the drawings do not reflect actual size, scale, or actual positional relationships. Additionally, any reference symbols placed within parentheses in this invention should not be construed as limiting the scope of the invention.

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1

[0044] This embodiment provides a method for loading Fe using ultrasonic-assisted loading. 50 Mn 30 Co 10 Cr 10 The martensitic reversal transformation of metastable high-entropy alloys specifically includes the following steps:

[0045] The atomic ratio of S1, FeMnCoCr is 5:3:1:1. Converted to mass ratio, in this example, the content is 18.836g of Fe elemental particles, 9.369g of Cr elemental particles, 10.619g of Co elemental particles, and 62.957g of FeMn alloy block. The Fe, Co, and Cr elemental particles and FeMn alloy block (mass ratio 1:1) are weighed and mixed.

[0046] Fe, Co, and Cr elemental particles and FeMn alloy blocks (mass ratio 1:1) were melted in a vacuum induction melting furnace under an argon atmosphere at a melting temperature of 1600℃. After the metal was completely melted, the furnace was held at this temperature for another 5 minutes to ensure uniform mixing. The molten metal was then rapidly poured into a water-cooled copper mold to obtain Fe... 50 Mn 30 Cr 10 Co 10 Metastable high-entropy alloy molded parts;

[0047] S2. The cast part is subjected to homogenization annealing heat treatment at 1200℃ for 2 hours to obtain Fe with uniform element distribution. 50 Mn 30 Cr 10 Co 10 Metastable high-entropy alloys;

[0048] S3, Prepared Fe 50 Mn 30 Cr 10 Co 10 Metastable high-entropy alloys are cut into stretched strips (the size of the stretched strips is not specifically limited and can be set according to actual needs or processing conditions), and subjected to pre-stretch deformation treatment with a deformation amount of 60% of the fracture elongation. Stress induces martensitic transformation, yielding Fe alloys containing 58.5% FCC phase and 41.5% HCP phase. 50 Mn 30 Cr 10 Co 10 Metastable high-entropy alloys;

[0049] S4. The stretched metastable high-entropy alloy was subjected to ultrasonic treatment using ultrasonic-assisted forming technology. The ultrasonic vibration frequency was 20 kHz, the holding pressure was 1000 N, and the ultrasonic time was 10 min, inducing martensitic reversal transformation to obtain Fe with 89.6% FCC phase and 10.4% HCP phase. 50 Mn 30 Cr 10 Co 10 Metastable high-entropy alloy.

[0050] The above-mentioned ultrasonic-assisted forming technology can be used as follows: Figure 2The ultrasonic-assisted shaping device shown includes a support 10, a transducer 20 connected to the support 10, an ultrasonic power supply 90 connected to the transducer, an amplitude transformer 30 connected to the transducer, a tool head 50, and a support 40 disposed between the amplitude transformer 30 and the tool head 50. A base 70 is positioned corresponding to the tool head 50, and limit blocks 80 and 81 are provided on the base corresponding to the side of the tool head. A sample 60 can be placed between the two limit blocks 80 and 81. The amplitude transformer transmits the high-frequency vibration to the tool head, thereby shaping Fe. 50 Mn 30 Co 10 Cr 10 Metastable high-entropy alloys are subjected to ultrasonic treatment.

[0051] Example 2

[0052] Except for the ultrasound time of 20 minutes, everything else is the same as in Example 1.

[0053] Example 3

[0054] Except for the ultrasound time of 30 minutes, everything else is the same as in Example 1.

[0055] Comparative Example 1

[0056] Except for the ultrasound time being 0 min, everything else is the same as in Example 1.

[0057] Depend on Figure 3 The phase distribution diagram results show that the metastable high-entropy alloy in the original state (ultrasonic treatment for 0 min) of Comparative Example 1 has 58.5% FCC phase and 41.5% HCP phase. The novel and efficient treatment method of this invention for inducing martensitic reversal in metastable high-entropy alloys is as follows:

[0058] (a) such as Figure 4 As shown, in Example 1, Fe was treated with an ultrasonic loading time of 10 min. 50 Mn 30 Co 10 Cr 10 Metastable high-entropy alloys contain 77% FCC phase and 23% HCP phase;

[0059] (b) such as Figure 5 As shown, in Example 2, Fe was treated with an ultrasonic loading time of 20 min. 50 Mn 30 Co 10 Cr 10 Metastable high-entropy alloys contain 84% FCC phase and 16% HCP phase;

[0060] (c) such as Figure 6As shown, in Example 3, Fe was treated with an ultrasonic loading time of 30 min. 50 Mn 30 Co 10 Cr 10 Metastable high-entropy alloys contain 89.6% FCC phase and 10.4% HCP phase.

[0061] As can be seen from the above, compared with the Fe obtained in the comparative example without ultrasonic treatment, 50 Mn 30 Co 10 Cr 10 Metastable high-entropy alloys, Fe treated with ultrasonic loading times of 10 min, 20 min, and 30 min. 50 Mn 30 Co 10 Cr 10 Metastable high-entropy alloys exhibited HCP phase transformations of 18.5%, 25.5%, and 31.1% respectively into FCC phases, achieving different degrees of martensitic reversal transformation.

[0062] The experimental results of this invention show that ultrasonic-assisted loading can achieve Fe 50 Mn 30 Co 10 Cr 10 The martensitic reversal transformation of metastable high-entropy alloys provides a new method for this transformation, promoting its application in the field of shape memory alloys.

[0063] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for inducing martensitic reversal transformation in FeMnCoCr metastable high-entropy alloys, characterized in that, Includes the following steps: Step S1: Determine the mass of Fe, Co, and Cr elemental particles and FeMn alloy blocks according to the molar ratio of alloying elements, mix them evenly, and then melt and cast them to obtain FeMnCoCr alloy molded parts. Step S2: Anneal the alloy forming part to obtain the FeMnCoCr metastable high-entropy alloy; Step S3: Cut the FeMnCoCr metastable high-entropy alloy into strips and perform stretching treatment; Step S4: The stretched FeMnCoCr metastable high-entropy alloy is subjected to ultrasonic treatment.

2. The method according to claim 1, characterized in that, The composition of the FeMnCoCr metastable high-entropy alloy described in step S1 is calculated by molar ratio as follows: Fe: 40% to 60%, Mn: 20% to 40%, Co: 5% to 15%, Cr: 5% to 15%; Preferably, the composition of the FeMnCoCr metastable high-entropy alloy is calculated by molar ratio as follows: Fe: 45% to 55%, Mn: 25% to 35%, Co: 5% to 15%, Cr: 5% to 15%; More preferably, the composition of the FeMnCoCr metastable high-entropy alloy is calculated by molar ratio as follows: Fe: 50%, Mn: 30%, Co: 10%, Cr: 10%.

3. The method according to claim 1, characterized in that, In step S1, the mass ratio of Fe to Mn in the FeMn alloy block is 1:0.5 to 1:2, preferably 1:1; Preferably, the purity of the Fe, Co, and Cr elemental particles and the FeMn alloy block is 99.5% or higher, and more preferably 99.9% or higher.

4. The method according to any one of claims 1 to 3, characterized in that, The melting described in step S1 is carried out in a vacuum induction melting furnace. Specifically, the uniformly mixed alloy elements are melted in an inert gas atmosphere, and the resulting molten metal is then cast into a water-cooled copper mold to obtain FeMnCoCr alloy molded parts.

5. The method according to claim 4, characterized in that, When melting is carried out in a vacuum induction melting furnace, the FeMn alloy block is placed at the bottom of the vacuum induction melting furnace.

6. The method according to any one of claims 1 to 5, characterized in that, The annealing conditions in step S2 are annealing at 1000°C to 1500°C for 1 to 3 hours, preferably annealing at 1100°C to 1300°C for 1.5 to 2.5 hours.

7. The method according to any one of claims 1 to 6, characterized in that, The tensile deformation in step S3 is 45% to 75% of the elongation at break, preferably 50% to 70%.

8. The method according to any one of claims 1 to 7, characterized in that, The ultrasonic treatment described in step S4 employs ultrasonic-assisted shaping technology.

9. The method according to claim 8, characterized in that, The frequency of the ultrasonic vibration in the ultrasonic treatment described in step S4 is 2.0 × 10⁻⁶. 4 Hz to 2.0×10 12 Hz, holding pressure is 700N to 1300N, ultrasonic time is 0min to 50min, excluding 0min; Preferably, the frequency of the ultrasonic vibration is 2.0 × 10⁻⁶. 4 Hz to 10 12 The Hz, the load pressure is 900N to 1100N, and the ultrasonic time is 5min to 40min.

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