Multi-principal-element alloy with high strength and high plasticity at room temperature and low temperature and preparation method of multi-principal-element alloy

Abstract

The invention provides a multi-principal-element alloy with high strength and high plasticity at room temperature and low temperature, the multi-principal-element alloy comprises NiaCobCrcAldNbeTafTig, a, b, c, d, e, f and g respectively represent atomic percentage contents of corresponding elements, a is greater than or equal to 30 and less than or equal to 50 at.%, b is greater than or equal to 20 and less than or equal to 50 at.%, c is greater than or equal to 0 and less than or equal to 30 at.%, d is greater than or equal to 0 and less than or equal to 5 at.%, e is greater than or equal to 0 and less than or equal to 5 at.%, f is greater than or equal to 0 and less than or equal to 5 at.%, g is greater than or equal to 0 and less than or equal to 5 at. The invention also provides a preparation method of the multi-principal element alloy with high strength and high plasticity at room temperature and low temperature. The method is simple in process and high in repeatability, the double-increasing effect of strength and plasticity under the low-temperature condition can be achieved, the technical problem of low-temperature brittle failure of a structural alloy material can be effectively solved, and the method has high industrial application value and wide industrial application prospects. The invention belongs to the technical field of metal materials and preparation thereof.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal materials and preparation thereof, and specifically relates to a multi-principal-component alloy having high strength and high plasticity at room temperature and low temperature and a preparation method thereof. Background Art

[0002] With the rapid development of low-temperature fields such as deep space exploration, polar scientific research, and low-temperature storage and transportation, higher and higher requirements are placed on the performance of cryogenic materials. At the same time, there have been many painful lessons in history of low-temperature brittle fracture of rails, bridges, pressure vessels, ships, and chemical equipment under low-temperature conditions. The safety of cryogenic components has also attracted more and more attention from various countries. At present, research on low-temperature metal materials at home and abroad is mainly focused on common structural materials such as aluminum alloys, steel, and titanium alloys. Existing studies have shown that the strength of the above-mentioned alloy materials will increase under low-temperature conditions, but their plasticity and toughness will decrease, leading to low-temperature brittle fracture. Therefore, solving the problem of low-temperature brittle fracture of alloy materials and achieving the dual-increase effect of strength and plasticity under low-temperature conditions are urgent problems that metal workers in various countries need to solve.

[0003] The design concept of multi-principal alloys based on the concept of "entropy value" provides an effective way to design high-performance metal materials. The unique properties of multi-principal alloys, such as high composition entropy, large lattice distortion and slow diffusion effect, make them exhibit a series of excellent properties different from traditional alloys, such as high hardness, high wear resistance, corrosion resistance and good radiation resistance, and can be used as ideal structural materials. In particular, face-centered cubic (FCC) structure multi-principal alloys usually have low stacking fault energy, and their stacking fault energy is even lower under liquid nitrogen or even liquid helium conditions. This ensures that FCC structure multi-principal alloys are easy to stimulate various stacking fault-related deformation mechanisms under low temperature conditions, such as high-density stacking faults, deformation twins and deformation-induced phase transformation, thereby ensuring that the alloy has excellent work hardening ability and plasticity under low temperature conditions. By adding micro-alloying elements to regulate the alloy lattice distortion and introducing nano-precipitation phases through subsequent heat treatment, it can ensure that it obtains high strength under low temperature excellent plasticity conditions. Therefore, it is expected to design alloy materials with both high strength and high plasticity at room temperature and low temperature conditions based on FCC structure multi-principal alloys. Summary of the invention

[0004] The purpose of the present invention is to provide a multi-principal component alloy having high strength and high plasticity at room temperature and low temperature and a preparation method thereof, so as to solve the technical problem that the existing alloy materials cannot simultaneously improve the strength and plasticity under low temperature conditions, resulting in low-temperature brittle fracture.

[0005] To achieve the above object, the technical solution adopted by the present invention is: to provide a multi-principal alloy having both high strength and high plasticity at room temperature and low temperature, wherein the components of the multi-principal alloy are Ni a Cob Cr c Al d Nb e Ta f Ti g , a, b, c, d, e, f, and g respectively represent the atomic percentage content of the corresponding elements, where 30≤a≤50at.%, 20≤b≤50at.%, 0≤c≤30at.%, 0≤d≤5at.%, 0≤e≤5at.%, 0≤f≤5at.%, 0≤g≤5at.%, d+e+f+g≤12at.%, and a+b+c+d+e+f+g=100at.%.

[0006] Preferably, the multi-principal component alloy has a single-phase FCC structure or a structure in which a nanoscale coherent L12 phase is dispersed in an FCC matrix.

[0007] The present invention also provides a method for preparing the multi-principal-component alloy having high strength and high plasticity at room temperature and low temperature as described in any one of the above, comprising the following steps:

[0008] (1) Accurately weigh the raw materials in proportion and mix them;

[0009] (2) vacuum melting the raw materials to obtain a multi-principal alloy ingot;

[0010] (3) performing high temperature homogenization treatment on the multi-principal alloy ingot to obtain a homogenized ingot;

[0011] (4) The homogenized ingot is subjected to a large deformation treatment, followed by a recrystallization treatment and an aging treatment, to obtain a multi-principal component alloy having both high strength and high plasticity at room temperature and low temperature.

[0012] Preferably, in step (1), Ni, Co, Cr, Al, Nb, Ta and Ti metal blocks are used as raw materials, and the purity of the above metal blocks is not less than 99.5%.

[0013] Preferably, in step (1), the raw materials are pretreated before weighing, and the specific process is: use mechanical grinding to remove the oxide scale on the surface of the Ni, Co, Cr, Al, Nb, Ta and Ti metal blocks, and then use acetone and alcohol solution to ultrasonically clean the above metal blocks for 5-10 minutes in turn, and blow dry for use.

[0014] Preferably, in step (2), the raw materials are vacuum melted in a vacuum induction melting furnace, heated to 1800-2200° C., and kept warm for 20-30 minutes; after vacuum melting, the molten metal is poured into a steel mold for cooling.

[0015] Preferably, in step (3), the specific process of high temperature homogenization treatment is: keeping the multi-principal alloy ingot at 1200° C. for 10-15 hours and water quenching.

[0016] In the present invention, the purpose of high temperature homogenization treatment is to eliminate component segregation and obtain a homogenized structure.

[0017] Preferably, in step (4), the specific process of large deformation treatment is: performing multiple rolling on the homogenized ingot, the rolling temperature is room temperature, the rolling passes are 3-6 times, and the total rolling amount is 70-90%.

[0018] In the present invention, the purpose of large deformation treatment is to cooperate with the subsequent recrystallization treatment to improve the grain structure.

[0019] Preferably, in step (4), the specific process of the recrystallization treatment is: heat treating the multi-principal alloy ingot after the large deformation treatment at 900-1200° C. for 1-60 min, and water quenching.

[0020] In the present invention, the purpose of the recrystallization treatment is to obtain a different grain structure.

[0021] Preferably, in step (4), the specific process of the aging treatment is: heat treating the multi-principal alloy ingot after recrystallization treatment at 650-800°C for 0-100h, and water quenching.

[0022] In the present invention, the purpose of aging treatment is to introduce precipitation strengthening phase.

[0023] The present invention provides a multi-principal alloy having high strength and high plasticity at room temperature and low temperature and a preparation method thereof. Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The multi-principal alloy of the present invention is obtained by combining "vacuum melting" with "deformation-heat treatment process". The preparation process is reasonable and simple, the preparation process is highly repeatable, and industrial mass production can be achieved.

[0025] (2) The multi-principal alloy of the present invention has a simple microstructure, and has a single-phase FCC structure or a nanoscale coherent L12 phase dispersed in an FCC matrix. By controlling the parameters of the "deformation-heat treatment process", the matrix grain size, precipitated phase size and volume fraction can be changed, thereby achieving regulation of the mechanical properties at room temperature and low temperature conditions.

[0026] (3) In the present invention, the addition of Al, Nb, Ta, and Ti elements can effectively improve the lattice distortion of the FCC structure matrix. At the same time, Nb, Ta, and Ti elements can improve the brittleness of the L12 phase, effectively improve the anti-phase boundary energy of the L12 phase, and then improve the precipitation strengthening effect of the L12 phase, which is helpful to obtain a high-strength and high-plasticity L12 phase precipitation-strengthened FCC structure multi-principal component alloy.

[0027] (4) The multi-principal alloy of the present invention has low stacking fault energy and can exhibit a dual enhancement effect of strength and plasticity under low temperature conditions, and has high industrial application value.

[0028] The process of the invention is simple and highly repeatable, can achieve a dual-increasing effect of strength and plasticity under low temperature conditions, can effectively solve the technical problem of low-temperature brittle fracture of structural alloy materials, and has great industrial application value and broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 The Ni prepared in Example 1 of the present invention 45 Co 23 Cr 23 Al 4.5 Nb 4.5 Microstructure images of multi-principal alloys, where (a) is an EBSD photo; (b) is a TEM microstructure photo of nano-sized granular L12 phase dispersed in the FCC matrix; the inset in (b) is a TEM microstructure photo of selected area electron diffraction along the

[100] axis of the FCC matrix;

[0031] Figure 2 The Ni prepared in Example 2 of the present invention 34 Co 33 Cr 24 Al 4.5 Nb 2.5 Electron backscattered diffraction (EBSD) images of Ta1Ti1 multi-principal alloy;

[0032] Figure 3 The Ni prepared in Example 3 of the present invention 46 Co 45 Al 4.5 Nb 2.5Microstructure images of Ta1Ti1 multi-principal alloy, where (a) is an EBSD image; (b) is a TEM image of nano-sized granular L12 phase dispersed in the FCC matrix;

[0033] Figure 4 The tensile stress-strain curves of the multi-principal alloys prepared in Examples 1-3 of the present invention at room temperature (298K) and low temperature (77K) conditions. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application is further described in detail in conjunction with the embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. The methods used in the present invention are conventional methods unless otherwise specified; the raw materials and devices used are conventional commercial products unless otherwise specified.

[0035] In order to verify the reliability of the effect of the present invention, the present invention is described below in conjunction with Examples 1-3.

[0036] Example 1

[0037] This embodiment provides a multi-principal alloy having high strength and high plasticity at room temperature and low temperature. The components of the multi-principal alloy are Ni 45 Co 23 Cr 23 Al 4.5 Nb 4.5 , where the ratio of each element is atomic molar percentage, namely Ni 45at.%, Co23at.%, Cr 23at.%, Al 4.5at.%, Nb 4.5at.%.

[0038] This embodiment also provides a method for preparing the multi-principal component alloy having both high strength and high plasticity at room temperature and low temperature, comprising the following steps:

[0039] (1) Raw material pretreatment and batching: Ni, Co, Cr, Al, and Nb metal blocks are used as raw materials, and the purity of the above metal blocks is not less than 99.5%; the oxide scale on the surface of the raw materials is removed by mechanical grinding, and then the raw materials are ultrasonically cleaned for 5-10 minutes using acetone and alcohol solution in turn, and blown dry for use; according to the atomic molar percentage of Ni, Co, Cr, Al, and Nb elements, the Ni, Co, Cr, Al, and Nb metal blocks are accurately weighed using an electronic balance and mixed.

[0040] (2) Vacuum melting: Place Ni, Co, Cr, Al, and Nb metal blocks in a vacuum induction melting furnace, heat to 1900°C and keep warm for 15 minutes for vacuum melting; then pour the molten metal into a steel mold and cool it to obtain a multi-principal alloy ingot.

[0041] (3) Homogenization treatment: The multi-principal alloy ingot is placed at 1200°C for 10 hours for high temperature homogenization treatment, and then water quenched to obtain a homogenized ingot.

[0042] (4) Deformation-heat treatment process: The homogenized ingot is subjected to multi-pass rolling at room temperature, with four passes, and the total reduction is ensured to be 80%; the rolled multi-principal alloy ingot is then placed at 1150°C for recrystallization treatment for 10 min, followed by water quenching; the recrystallized multi-principal alloy ingot is then placed at 700°C for aging treatment for 2 h, followed by water quenching, to obtain a multi-principal alloy with high strength and high plasticity at room temperature and low temperature, named Ni 45 Co 23 Cr 23 Al 4.5 Nb 4.5 Multi-principal alloy.

[0043] The Ni prepared in Example 1 45 Co 23 Cr 23 Al 4.5 Nb 4.5 The EBSD photos of multi-principal alloys are shown in the following figure: Figure 1 (a) shows the TEM micrograph of the Figure 1 (b) as shown.

[0044] Depend on Figure 1 (a) It can be seen that Ni 45 Co 23 Cr 23 Al 4.5 Nb 4.5 The interior of the multi-principal alloy shows an equiaxed grain structure with an average grain size of ~53μm. Figure 1 (b) It can be seen that Ni 45 Co 23 Cr 23 Al 4.5 Nb 4.5 The interior of the grains of the multi-principal alloy is a structure in which the nanoscale coherent L12 phase is dispersed in the FCC matrix, with an average particle size of ~13.7nm.

[0045] The Ni prepared in Example 1 45 Co 23 Cr 23 Al 4.5 Nb4.5 Mechanical analysis of multi-principal alloys was performed, and the tensile stress-strain curves at room temperature (298K) and low temperature (77K) were as follows: Figure 4 shown.

[0046] Depend on Figure 4 It can be seen that Ni 45 Co 23 Cr 23 Al 4.5 Nb 4.5 The room temperature (298K) yield strength of the multi-principal alloy is ~1098MPa, the tensile strength is ~1516MPa, and the tensile strain is ~39.2%; its liquid nitrogen (77K) yield strength is ~1220MPa, the tensile strength is ~1816MPa, and the tensile strain is ~48.9%.

[0047] Example 2

[0048] This embodiment provides a multi-principal alloy having high strength and high plasticity at room temperature and low temperature. The components of the multi-principal alloy are Ni 34 Co 33 Cr 24 Al 4.5 Nb 2.5 Ta1Ti1, wherein the ratio of each element is atomic molar percentage, namely Ni 34at.%, Co 33at.%, Cr 24at.%, Al 4.5at.%, Nb 2.5at.%, Ta 1.0at.%, Ti 1.0at.%.

[0049] This embodiment also provides a method for preparing the multi-principal component alloy having both high strength and high plasticity at room temperature and low temperature, comprising the following steps:

[0050] (1) Raw material pretreatment and batching: Ni, Co, Cr, Al, Nb, Ta, and Ti metal blocks are used as raw materials, and the purity of the above metal blocks is not less than 99.5%; the oxide scale on the surface of the raw materials is removed by mechanical grinding, and then the raw materials are ultrasonically cleaned for 5-10 minutes using acetone and alcohol solution in turn, and blown dry for use; according to the atomic molar percentage of Ni, Co, Cr, Al, Nb, Ta, and Ti elements, the Ni, Co, Cr, Al, Nb, Ta, and Ti metal blocks are accurately weighed using an electronic balance and mixed.

[0051] (2) Vacuum melting: Place Ni, Co, Cr, Al, Nb, Ta, and Ti metal blocks in a vacuum induction melting furnace, heat to 1900°C and keep warm for 15 minutes for vacuum melting; then pour the molten metal into a steel mold and cool it to obtain a multi-principal alloy ingot.

[0052] (3) Homogenization treatment: The multi-principal alloy ingot is placed at 1200°C for 10 hours for high temperature homogenization treatment, and then water quenched to obtain a homogenized ingot.

[0053] (4) Deformation-heat treatment process: The homogenized ingot is subjected to multi-pass rolling at room temperature, with four passes, and the total reduction is ensured to be 80%; the rolled multi-principal alloy ingot is then placed at 1200°C for 10 min for recrystallization treatment, followed by water quenching to obtain a multi-principal alloy with high strength and high plasticity at room temperature and low temperature, named Ni 34 Co 33 Cr 24 Al 4.5 Nb 2.5 Ta1Ti1 multi-principal alloy.

[0054] The Ni prepared in Example 2 34 Co 33 Cr 24 Al 4.5 Nb 2.5 The structure of Ta1Ti1 multi-principal alloy is analyzed, and its EBSD photo is as follows Figure 2 shown.

[0055] Depend on Figure 2 It can be seen that Ni 34 Co 33 Cr 24 Al 4.5 Nb 2.5 The interior of the Ta1Ti1 multi-principal alloy is a single-phase FCC structure, showing an equiaxed grain structure with an average grain size of ~32μm.

[0056] The Ni prepared in Example 2 34 Co 33 Cr 24 Al 4.5 Nb 2.5 The mechanical analysis of Ta1Ti1 multi-principal alloy is carried out, and its tensile stress-strain curves at room temperature (298K) and low temperature (77K) are as follows Figure 4 shown.

[0057] Depend on Figure 4 It can be seen that Ni 34 Co 33 Cr 24 Al 4.5 Nb 2.5The room temperature (298K) yield strength of the Ta1Ti1 multi-principal alloy is ~667MPa, the tensile strength is ~1083MPa, and the tensile strain is ~54.2%; its liquid nitrogen (77K) yield strength is ~898MPa, the tensile strength is ~1455MPa, and the tensile strain is ~56.2%.

[0058] Example 3

[0059] This embodiment provides a multi-principal alloy having high strength and high plasticity at room temperature and low temperature. The components of the multi-principal alloy are Ni 46 Co 45 Al 4.5 Nb 2.5 Ta1Ti1, wherein the ratio of each element is atomic molar percentage, i.e. Ni 46at.%, Co 45at.%, Al 4.5at.%, Nb 2.5at.%, Ta 1.0at.%, Ti 1.0at.%.

[0060] This embodiment also provides a method for preparing the multi-principal component alloy having both high strength and high plasticity at room temperature and low temperature, comprising the following steps:

[0061] (1) Raw material pretreatment and batching: Ni, Co, Al, Nb, Ta, and Ti metal blocks are used as raw materials, and the purity of the above metal blocks is not less than 99.5%; the oxide scale on the surface of the raw materials is removed by mechanical grinding, and then the raw materials are ultrasonically cleaned for 5-10 minutes using acetone and alcohol solution in turn, and blown dry for use; according to the atomic molar percentage of Ni, Co, Al, Nb, Ta, and Ti elements, the Ni, Co, Al, Nb, Ta, and Ti metal blocks are accurately weighed using an electronic balance and mixed.

[0062] (2) Vacuum melting: Place Ni, Co, Al, Nb, Ta, and Ti metal blocks in a vacuum induction melting furnace, heat to 1900°C and keep warm for 15 minutes for vacuum melting; then pour the molten metal into a steel mold and cool it to obtain a multi-principal alloy ingot.

[0063] (3) Homogenization treatment: The multi-principal alloy ingot is placed at 1200°C for 10 hours for high temperature homogenization treatment, and then water quenched to obtain a homogenized ingot.

[0064] (4) Deformation-heat treatment process: The homogenized ingot is subjected to multi-pass rolling at room temperature, with four passes, and the total reduction is ensured to be 80%; the rolled multi-principal alloy ingot is then subjected to recrystallization treatment at 1200°C for 10 min, followed by water quenching; the recrystallized multi-principal alloy ingot is then subjected to aging treatment at 650°C for 10 h, followed by water quenching, to obtain a multi-principal alloy with high strength and high plasticity at room temperature and low temperature, named Ni46 Co 45 Al 4.5 Nb 2.5 Ta1Ti1 multi-principal alloy.

[0065] The Ni prepared in Example 3 46 Co 45 Al 4.5 Nb 2.5 The structure of Ta1Ti1 multi-principal alloy is analyzed, and its EBSD photo is as follows Figure 3 (a) shows the TEM micrograph of the Figure 3 (b) as shown.

[0066] Depend on Figure 3 (a) It can be seen that Ni 46 Co 45 Al 4.5 Nb 2.5 The interior of the Ta1Ti1 multi-principal alloy shows an equiaxed grain structure with an average grain size of ~62μm. Figure 3 (b) It can be seen that Ni 46 Co 45 Al 4.5 Nb 2.5 The interior of the grains of the Ta1Ti1 multi-principal alloy is a structure in which the nanoscale coherent L12 phase is dispersed in the FCC matrix, with an average particle size of ~8.5nm.

[0067] The Ni prepared in Example 3 46 Co 45 Al 4.5 Nb 2.5 Mechanical analysis of Ta1Ti1 multi-principal alloys was performed, and the tensile stress-strain curves at room temperature (298K) and low temperature (77K) are shown in Figure 4 shown.

[0068] Depend on Figure 4 It can be seen that Ni 46 Co 45 Al 4.5 Nb 2.5 The room temperature (298K) yield strength of the Ta1Ti1 multi-principal alloy is ~1023MPa, the tensile strength is ~1447MPa, and the tensile strain is ~30.4%; its liquid nitrogen (77K) yield strength is ~1135MPa, the tensile strength is ~1762MPa, and the tensile strain is ~40.2%.

[0069] In order to more intuitively compare the mechanical properties of the multi-principal alloys of Examples 1-3, the following Table 1 is formed.

[0070] Table 1 Mechanical properties of multi-principal alloys of Examples 1-3

[0071]

[0072] It can be seen from Table 1 that the multi-principal component alloy prepared by the present invention has excellent tensile strength, yield strength, and elongation at room temperature (298K) and low temperature (77K), and when the internal structure of the multi-principal component alloy is a single-phase FCC structure, excellent room temperature and low temperature performance can also be obtained. This shows that the multi-principal component alloy prepared by the present invention can have both high strength and high plasticity at room temperature and low temperature, that is, the multi-principal component alloy of the present invention achieves a dual increase in strength and plasticity.

[0073] It can be seen from Examples 1-3 that the multi-principal component alloy having both high strength and high plasticity at room temperature and low temperature of the present invention is easy to prepare, and can achieve a dual-increase effect of strength and plasticity under both room temperature and low temperature conditions, can effectively solve the technical problem of low-temperature brittle fracture of structural alloy materials, and has great industrial application prospects.

[0074] It should be noted that: in the above embodiments 1-3, in step (2), the temperature of vacuum melting is 1900°C and the holding time is 15 minutes. This is only a preferred embodiment. In actual production, the temperature of vacuum melting can be 1800-2200°C and the holding time can be 20-30 minutes, which can be adaptively adjusted according to specific circumstances. In step (3), the temperature of high-temperature homogenization treatment is 1200°C and the holding time is 10 hours. This is only a preferred embodiment. In actual production, the temperature of high-temperature homogenization treatment can be 1200°C and the holding time can be 10-15 hours, which can be adaptively adjusted according to specific circumstances. In step (4), the number of rolling passes of room temperature multi-pass rolling is 4 times, and the total reduction is 80%. This is only a preferred embodiment. In actual production, the number of rolling passes of room temperature multi-pass rolling can be 3-6 times, and the total rolling amount can be 70-90%, which can be adaptively adjusted according to specific circumstances. In step (4), the process of recrystallization treatment is 1150℃ / 10min or 1200℃ / 10min, which is only a preferred embodiment. In actual production, the temperature of recrystallization treatment can be 900-1200℃, and the heat treatment time can be 1-60min, which can be adaptively adjusted according to specific circumstances. In step (4), the process of aging treatment is 700℃ / 2h or 0℃ / 0h or 650℃ / 10h, which is only a preferred embodiment. In actual production, the temperature of aging treatment can be 650-800℃, and the heat treatment time can be 0-100h, which can be adaptively adjusted according to specific circumstances.

[0075] In summary, the present invention provides a multi-principal component alloy having both high strength and high plasticity at room temperature and low temperature and a preparation method thereof. Compared with the prior art: (1) The multi-principal component alloy of the present invention is obtained by combining "vacuum melting" with "deformation-heat treatment process", the preparation process is reasonable and simple, the preparation process is highly repeatable, and industrial mass production can be achieved. (2) The multi-principal component alloy of the present invention has a simple microstructure, and has a single-phase FCC structure or a nanoscale coherent L12 phase dispersed in an FCC matrix. By controlling the parameters of the "deformation-heat treatment process", the matrix grain size, precipitated phase size and volume fraction can be changed, thereby achieving regulation of the mechanical properties at room temperature and low temperature conditions. (3) In the present invention, the addition of Al, Nb, Ta, and Ti elements can effectively improve the lattice distortion of the FCC structural matrix. At the same time, Nb, Ta, and Ti elements can improve the brittleness of the L12 phase, effectively improve the anti-phase boundary energy of the L12 phase, and then improve the precipitation strengthening effect of the L12 phase, which is helpful to obtain a high-strength and high-plasticity L12 phase precipitation-strengthened FCC structure multi-principal component alloy. (4) The multi-principal component alloy of the present invention has low stacking fault energy, can show a dual-increase effect of strength and plasticity under low temperature conditions, and has a high industrial application value. The process of the present invention is simple and has strong repeatability. It can achieve a dual-increase effect of strength and plasticity under low temperature conditions, can effectively solve the technical problem of low-temperature brittle fracture of structural alloy materials, and has a large industrial application value and broad industrial application prospects. The present invention can be widely used in the field of metal materials and their preparation technology.

[0076] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A multi-principal alloy having high strength and high plasticity at room temperature and low temperature, characterized in that: The composition of the multi-principal alloy is Ni a Co b Cr c Al d Nb e Ta f Ti g , a, b, c, d, e, f, and g respectively represent the atomic percentage content of the corresponding elements, where 30≤a≤50at.%, 20≤b≤50at.%, 0≤c≤30at.%, 0≤d≤5at.%, 0≤e≤5at.%, 0≤f≤5at.%, 0≤g≤5at.%, d+e+f+g≤12at.%, and a+b+c+d+e+f+g=100at.%.

2. The multi-principal alloy having high strength and high plasticity at room temperature and low temperature according to claim 1, characterized in that: The multi-principal alloy has a single-phase FCC structure or a structure in which a nano-scale coherent L12 phase is dispersed in an FCC matrix.

3. The method for preparing a multi-principal alloy having high strength and high plasticity at room temperature and low temperature as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: (1) Accurately weigh the raw materials in proportion and mix them; (2) vacuum melting the raw materials to obtain a multi-principal alloy ingot; (3) performing high temperature homogenization treatment on the multi-principal alloy ingot to obtain a homogenized ingot; (4) The homogenized ingot is subjected to a large deformation treatment, followed by a recrystallization treatment and an aging treatment, to obtain a multi-principal component alloy having both high strength and high plasticity at room temperature and low temperature.

4. The method for preparing a multi-principal alloy having high strength and high plasticity at room temperature and low temperature according to claim 3, characterized in that: In step (1), Ni, Co, Cr, Al, Nb, Ta and Ti metal blocks are used as raw materials, and the purity of the above metal blocks is not less than 99.5%.

5. The method for preparing a multi-principal alloy having high strength and high plasticity at room temperature and low temperature according to claim 4, characterized in that: In step (1), the raw materials are pretreated before weighing. The specific process is: use mechanical grinding to remove the oxide scale on the surface of Ni, Co, Cr, Al, Nb, Ta and Ti metal blocks, and then use acetone and alcohol solution to ultrasonically clean the above metal blocks for 5-10 minutes in turn, and blow dry for use.

6. The method for preparing a multi-principal alloy having high strength and high plasticity at room temperature and low temperature according to claim 3, characterized in that: In step (2), the raw materials are vacuum melted in a vacuum induction melting furnace, heated to 1800-2200° C., and kept warm for 20-30 minutes; after vacuum melting, the molten metal is poured into a steel mold for cooling.

7. The method for preparing a multi-principal alloy having high strength and high plasticity at room temperature and low temperature according to claim 3, characterized in that: In step (3), the specific process of high temperature homogenization treatment is: keeping the multi-principal alloy ingot at 1200° C. for 10-15 hours and quenching with water.

8. The method for preparing a multi-principal-component alloy having high strength and high plasticity at room temperature and low temperature according to claim 3, characterized in that: In step (4), the specific process of large deformation treatment is: the homogenized ingot is subjected to multi-pass rolling, the rolling temperature is room temperature, the rolling passes are 3-6 times, and the total rolling amount is 70-90%.

9. The method for preparing a multi-principal-component alloy having high strength and high plasticity at room temperature and low temperature according to claim 3, characterized in that: In step (4), the specific process of recrystallization treatment is: heat treating the multi-principal alloy ingot after large deformation treatment at 900-1200° C. for 1-60 min, and water quenching.

10. The method for preparing a multi-principal alloy having high strength and high plasticity at room temperature and low temperature according to claim 3, characterized in that: In step (4), the specific process of aging treatment is: heat treating the multi-principal alloy ingot after recrystallization treatment at 650-800°C for 0-100h, and water quenching.

Images