A high performance CrFeNi 2 Y x Medium-entropy alloy and preparation method thereof

Abstract

The invention discloses a high performance CrFeNi2Y x The medium entropy alloy is composed of Cr, Fe, Ni, and Y elements, and the atomic percentage of Cr, Fe, Ni, and Y is 1:1:2:x, wherein 0<x<1, and the alloy ingot can be obtained by arc melting and tumble casting. x The medium entropy alloy has a dual-phase structure of FCC and HCP, and has high strength and plasticity, high hardness and good wear resistance. In addition, the CrFeNi2Y x Medium-entropy alloys have good castability, uniform ingot structure, and do not contain precious metals. They are low in cost, suitable for large-scale production, and have broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of medium entropy alloys, and in particular to a high performance CrFeNi2Y x Medium-entropy alloy and method for preparing the same. Background Art

[0002] Medium-entropy alloys are a new type of alloy derived from the concept of high-entropy alloys. They use two to four main elements in an equimolar ratio or a nearly equimolar ratio to design alloys. Medium-entropy alloys usually form a single-phase solid solution with a single lattice structure, and their castability is relatively poor. At the same time, it is difficult to achieve a balance between the strength and plasticity of single-phase medium-entropy alloys: for example, medium-entropy alloys with a single-phase FCC structure have good plasticity but insufficient strength; medium-entropy alloys with a single-phase BCC structure or containing hard phase intermetallic compounds (such as B2 phase, HCP phase) have high strength but poor plasticity. Among them, CrCoFeNi is a commonly used medium-entropy alloy with a typical single-phase FCC structure. It has excellent plasticity at room temperature and low temperature, but its strength and hardness are relatively low. In addition, since CrCoFeNi alloys contain expensive Co elements, their large-scale application in industry is also limited. Therefore, it is particularly important to design a low-cost, high-performance Co-free medium-entropy alloy. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a high performance CrFeNi2Y x A medium-entropy alloy and a preparation method thereof, which have excellent comprehensive mechanical properties and low manufacturing cost.

[0004] The technical solution adopted by the present invention is:

[0005] The present invention provides a high performance CrFeNi2Y x A medium-entropy alloy is composed of Cr, Fe, Ni, and Y elements, and the atomic percentage of Cr, Fe, Ni, and Y is 1:1:2:x, 0<x<1.

[0006] Furthermore, the CrFeNi2Y x In the medium entropy alloy, 0<x<0.55, more preferably, 0.15≤x≤0.4, and within this range, CrFeNi2Y x The hardness of the medium entropy alloy ingot is greater than 200 HV, and the yield strength is greater than 400 MPa.

[0007] Furthermore, the CrFeNi2Y x Medium-entropy alloys have a two-phase structure.

[0008] Furthermore, the CrFeNi2Y x Medium entropy alloys have a dual-phase structure of FCC and HCP.

[0009] The present invention also provides a high performance CrFeNi2Y x A method for preparing a medium entropy alloy comprises the following steps:

[0010] (1) taking high-purity Cr, Fe, Ni, and Y single metals as raw materials and pre-treating them;

[0011] (2) weighing the pretreated Cr, Fe, Ni, and Y single metals in proportion for batching;

[0012] (3) Melting and casting Cr, Fe, Ni, and Y single metals to obtain CrFeNi2Y x Medium entropy alloy.

[0013] Furthermore, the step (1) is specifically as follows: firstly, immerse the Cr, Fe, Ni, and Y single metals in anhydrous ethanol respectively, and use ultrasonic cleaning for 1 to 3 times to remove the oxide scale and impurities on the surface of the Cr, Fe, Ni, and Y single metals, and then blow dry the cleaned single metals and store them.

[0014] Furthermore, the step (2) is specifically as follows: firstly, using an electronic balance to weigh Cr, Fe, Ni, and Y single metals in proportion, and then immersing the weighed Cr, Fe, Ni, and Y single metals in anhydrous ethanol respectively, using ultrasonic cleaning for 1 to 3 times to remove impurities introduced during the weighing process, and then blowing the cleaned single metals dry and storing them.

[0015] Furthermore, the step (3) is specifically as follows:

[0016] (31) The Cr, Fe, Ni, and Y single metal raw materials weighed in step (2) are placed in a copper crucible in a vacuum melting furnace, and a pure titanium ingot is placed in another copper crucible in the furnace. The furnace door is then closed, and the furnace is evacuated to below 5 Pa. High-purity argon gas is introduced to 0.01-0.05 MPa to wash the furnace 1-3 times, and then the furnace is evacuated again to 10 -3 Pa, and high-purity argon gas is introduced to 0.05MPa as protective gas;

[0017] (32) arc melting is started. After the arc is started, the pure titanium ingot is first melted for 2 to 3 minutes, and then the Cr, Fe, Ni, and Y single metal raw materials are melted. The arc current is 200A to 250A. After all the raw materials are melted, electromagnetic stirring is turned on. The electromagnetic stirring current is 2 to 3A. After maintaining for 1 to 5 minutes, the alloy liquid is cooled to obtain an initial ingot.

[0018] (33) turning the initial ingot over in the copper crucible and melting it again, the arc current is 200A-250A, after the initial ingot is completely melted, turning on the electromagnetic stirring, the electromagnetic stirring current is 2-3A, and after maintaining for 1-5 minutes, cooling the alloy liquid to obtain a secondary ingot;

[0019] (34) Repeat step (33) 3 to 6 times, and turn off the electromagnetic stirring during the last smelting. After the alloy liquid cools down, CrFeNi2Y x Medium entropy alloy button-shaped ingot;

[0020] (35) The CrFeNi2Y obtained in step (34) x The medium entropy alloy button-shaped ingot is cast in a rectangular copper mold to obtain CrFeNi2Y x Medium entropy alloy plate ingot.

[0021] Furthermore, the step (35) is specifically as follows: firstly, a layer of graphite plate is laid on the bottom of the copper crucible of the flip casting equipment, and then the CrFeNi2Y x The button-shaped ingot of the medium entropy alloy is placed in a copper crucible, the furnace door is closed, and after vacuuming, argon gas is filled to 0.1-0.4 MPa. The arc is turned on to melt the ingot in the copper crucible, and the arc current is 200A-250A. After melting for 80-150s, it is turned over and cast into a rectangular copper mold, and taken out after natural cooling in the furnace to obtain CrFeNi2Y x Medium entropy alloy plate ingot.

[0022] Furthermore, in the step (35), the flipping speed during the flip casting process is 90° within 2 seconds, and the natural cooling time after the flip casting is 15 to 20 minutes.

[0023] The beneficial effects of the present invention are:

[0024] (1) A high performance CrFeNi2Y x Medium entropy alloy is composed of four elements: Cr, Fe, Ni and Y. The addition of Y makes the alloy ingot form a two-phase structure containing FCC phase and HCP phase. Among them, the FCC phase rich in Cr, Fe and Ni has good plasticity, and the HCP phase rich in Ni and Y has high strength and hardness, so that CrFeNi2Y x Medium entropy alloy ingots have both high strength and plasticity, high hardness and good wear resistance;

[0025] (2) A high performance CrFeNi2Y x Medium-entropy alloys have good castability and uniform ingot structure. They are low in cost, suitable for large-scale production, and have broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, 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 some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 CrFeNi2Y obtained in Examples 1-4 and Comparative Examples of the present invention x XRD pattern of medium entropy alloy ingot;

[0028] Figure 2 CrFeNi2Y obtained in Example 1, Example 3, Example 4 and Comparative Example of the present invention x Scanning electron microscope images of medium entropy alloy ingots: (a) CrFeNi2, (b) CrFeNi2Y 0.15 , (c) CrFeNi2Y 0.4 , (d) CrFeNi2Y 0.55 ;

[0029] Figure 3 CrFeNi2Y obtained in Examples 1-4 and Comparative Examples of the present invention x Hardness curve of medium entropy alloy ingot;

[0030] Figure 4 CrFeNi2Y obtained in Examples 1-4 and Comparative Examples of the present invention x Room temperature compressive stress-strain curves of medium-entropy alloy ingots. DETAILED DESCRIPTION

[0031] The present invention provides a high performance CrFeNi2Y x Medium entropy alloy and preparation method thereof, in order to make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] The present invention is described in detail below with reference to the accompanying drawings.

[0033] Example 1

[0034] This embodiment provides a high performance CrFeNi2Y 0.15 Medium entropy alloy, composed of Cr, Fe, Ni, and Y elements, and the atomic percentage of Cr, Fe, Ni, and Y is 1:1:2:0.15.

[0035] The above CrFeNi2Y x The preparation method of medium entropy alloy is as follows:

[0036] (1) taking high-purity (purity>99.95wt%) Cr, Fe, Ni, Y single metals as raw materials and pre-treating them;

[0037] Specifically, the Cr, Fe, Ni, and Y single metals are immersed in anhydrous ethanol respectively, and ultrasonic cleaning is performed twice to remove the oxide scale and impurities on the surface of the Cr, Fe, Ni, and Y single metals, and then the cleaned single metals are blown dry and stored;

[0038] (2) weighing the pretreated Cr, Fe, Ni, and Y single metals in a molar ratio of 1:1:2:0.15 for batching;

[0039] Specifically, the Cr, Fe, Ni, and Y single metals are weighed in proportion using an electronic balance, and then the weighed Cr, Fe, Ni, and Y single metals are immersed in anhydrous ethanol respectively, and ultrasonic cleaning is performed twice to remove impurities introduced during the weighing process, and then the cleaned single metals are blown dry and stored;

[0040] (3) Melting and casting Cr, Fe, Ni, and Y single metals to obtain CrFeNi2Y 0.15 Medium entropy alloys;

[0041] Specifically:

[0042] (31) The Cr, Fe, Ni, and Y single metal raw materials weighed in step (2) are placed in a copper crucible in a vacuum melting furnace, and a pure titanium ingot is placed in another copper crucible in the furnace. The furnace door is then closed, the furnace is evacuated to 5 Pa, and high-purity argon gas is introduced to 0.05 MPa to wash the furnace, and then the furnace is evacuated again to 10 -3 Pa, and high-purity argon gas is introduced to 0.05MPa as protective gas;

[0043] (32) arc melting is started. After the arc is started, the pure titanium ingot is first melted for 2 min, and then the Cr, Fe, Ni, and Y single metal raw materials are melted. The arc current is 200 A. After all the raw materials are melted, electromagnetic stirring is turned on. The electromagnetic stirring current is 2 A. After maintaining for 2 min, the alloy liquid is cooled to obtain an initial ingot.

[0044] (33) Turning the initial ingot over in the copper crucible and melting it again, the arc current is 200A, after the initial ingot is completely melted, start electromagnetic stirring, the electromagnetic stirring current is 2A, keep it for 2min, and then cool the alloy liquid to obtain a secondary ingot;

[0045] (34) Repeat step (33) 3 times, and turn off the electromagnetic stirring during the last smelting. After the alloy liquid is cooled, CrFeNi2Y 0.15 Medium entropy alloy button-shaped ingot;

[0046] (35) A graphite plate is laid on the bottom of the copper crucible of the flip casting equipment, and then the CrFeNi2Y 0.15 The button-shaped ingot of the medium entropy alloy is placed in a copper crucible, the furnace door is closed, and after vacuuming, argon gas is filled to 0.1 MPa. The arc is turned on to melt the ingot in the copper crucible. The arc current is 200A. After melting for 100 seconds, it is flipped and cast into a rectangular copper mold. The flipping speed is 90° within 2 seconds. After cooling naturally in the furnace for 15 minutes, it is taken out to obtain CrFeNi2Y 0.15 Medium entropy alloy plate ingot.

[0047] Example 2

[0048] This embodiment provides a high performance CrFeNi2Y 0.25 Medium entropy alloy, composed of Cr, Fe, Ni, and Y elements, and the atomic percentage of Cr, Fe, Ni, and Y is 1:1:2:0.25.

[0049] The above CrFeNi2Y 0.25 The preparation method of the medium entropy alloy is the same as that in Example 1.

[0050] Example 3

[0051] This embodiment provides a high performance CrFeNi2Y 0.4 Medium entropy alloy, composed of Cr, Fe, Ni, and Y elements, and the atomic percentage of Cr, Fe, Ni, and Y is 1:1:2:0.4.

[0052] The above CrFeNi2Y 0.4 The preparation method of the medium entropy alloy is the same as that in Example 1.

[0053] Example 4

[0054] This embodiment provides a high performance CrFeNi2Y 0.55 Medium entropy alloy, composed of Cr, Fe, Ni, and Y elements, and the atomic percentage of Cr, Fe, Ni, and Y is 1:1:2:0.55.

[0055] The above CrFeNi2Y 0.55 The preparation method of the medium entropy alloy is the same as that in Example 1.

[0056] Example 5

[0057] This embodiment 5 provides a high performance CrFeNi2Y0.15 Medium entropy alloy, composed of Cr, Fe, Ni, and Y elements, and the atomic percentage of Cr, Fe, Ni, and Y is 1:1:2:0.15.

[0058] The above CrFeNi2Y 0.15 The preparation method of medium entropy alloy is as follows:

[0059] (1) taking high-purity (purity>99.95wt%) Cr, Fe, Ni, Y single metals as raw materials and pre-treating them;

[0060] Specifically, the Cr, Fe, Ni, and Y single metals are immersed in anhydrous ethanol respectively, and ultrasonic cleaning is performed twice to remove the oxide scale and impurities on the surface of the Cr, Fe, Ni, and Y single metals, and then the cleaned single metals are blown dry and stored;

[0061] (2) weighing the pretreated Cr, Fe, Ni, and Y single metals in a molar ratio of 1:1:2:0.15 for batching;

[0062] Specifically, the Cr, Fe, Ni, and Y single metals are weighed in proportion using an electronic balance, and then the weighed Cr, Fe, Ni, and Y single metals are immersed in anhydrous ethanol respectively, and ultrasonic cleaning is performed for 3 times to remove impurities introduced during the weighing process, and then the cleaned single metals are blown dry and stored;

[0063] (3) Melting and casting Cr, Fe, Ni, and Y single metals to obtain CrFeNi2Y 0.15 Medium entropy alloys;

[0064] Specifically:

[0065] (31) The Cr, Fe, Ni, and Y single metal raw materials weighed in step (2) are placed in a copper crucible in a vacuum melting furnace, and a pure titanium ingot is placed in another copper crucible in the furnace. The furnace door is then closed, the furnace is evacuated to 5 Pa, and high-purity argon gas is introduced to 0.05 MPa to wash the furnace twice, and then the furnace is evacuated again to 10 -3 Pa, and high-purity argon gas is introduced to 0.05MPa as protective gas;

[0066] (32) arc melting is started. After the arc is started, the pure titanium ingot is first melted for 3 min, and then the Cr, Fe, Ni, and Y single metal raw materials are melted. The arc current is 250 A. After all the raw materials are melted, electromagnetic stirring is turned on. The electromagnetic stirring current is 3 A. After maintaining for 5 min, the alloy liquid is cooled to obtain an initial ingot.

[0067] (33) The initial ingot is turned over in the copper crucible and smelted again with an arc current of 250 A. After the initial ingot is completely melted, electromagnetic stirring is turned on with an electromagnetic stirring current of 3 A. After maintaining for 3 min, the alloy liquid is cooled to obtain a secondary ingot.

[0068] (34) Repeat step (33) 3 times, and turn off the electromagnetic stirring during the last smelting. After the alloy liquid cools down, CrFeNi2Y 0.15 Medium entropy alloy button-shaped ingot;

[0069] (35) A graphite plate is laid on the bottom of the copper crucible of the flip casting equipment, and then the CrFeNi2Y 0.15 The button-shaped ingot of the medium entropy alloy is placed in a copper crucible, the furnace door is closed, and after vacuuming, argon gas is filled to 0.4MPa. The arc is turned on to melt the ingot in the copper crucible. The arc current is 250A. After melting for 150s, it is flipped and cast into a rectangular copper mold. The flipping speed is 90° within 2s. After cooling naturally in the furnace for 20min, it is taken out to obtain CrFeNi2Y 0.15 Medium entropy alloy plate ingot.

[0070] Comparative Example

[0071] The difference between this comparative example and Example 1 is that this comparative example provides a CrFeNi2 medium entropy alloy composed of Cr, Fe, Ni, and elements, and the atomic percentage of Cr, Fe, and Ni is 1:1:2.

[0072] The preparation method of the above-mentioned CrFeNi2 medium entropy alloy is the same as that in Example 1.

[0073] Take the CrFeNi2Y prepared in the above Examples 1-4 and Comparative Examples x The medium entropy alloy ingot samples were tested as follows:

[0074] like Figure 1 As shown, the CrFeNi2Y prepared in the above Examples 1-4 and Comparative Examples x The medium entropy alloy ingot sample was subjected to XRD test. It can be seen from the XRD diagram that the CrFeNi2Y x The medium entropy alloy ingot sample only contains FCC phase, while the CrFeNi2Y x The medium entropy alloy ingot sample has a two-phase structure of FCC phase and HCP phase. Among them, the FCC phase rich in Cr, Fe, and Ni has good plasticity, and the HCP phase rich in Ni and Y has high strength and hardness, making CrFeNi2Y x Medium entropy alloy ingots have both high strength and plasticity.

[0075] like Figure 2 As shown, the CrFeNi2Y prepared in Examples 1, 3, 4 and Comparative Example x The medium entropy alloy ingot sample was tested using a scanning electron microscope, where: Figure 2 (a) is the CrFeNi2 medium entropy alloy ingot of Comparative Example 1, (b) is the CrFeNi2Y 0.15 Medium entropy alloy ingot, (c) CrFeNi2Y of Example 3 0.4 Medium entropy alloy ingot, (d) is CrFeNi2Y of Example 4 0.55 Medium entropy alloy ingot, and the dark rod-shaped or spherical structures in (b)-(d) are FCC phases, and the light-colored structures between FCC phases are intermetallic compound phases - HCP hard phases. Figure 2 It can be seen from (a)-(d) that with the increase of Y content, the volume fraction of HCP hard phase gradually increases, and the FCC phase and HCP phase are evenly distributed.

[0076] like Figure 3 As shown, the CrFeNi2Y obtained in the above Examples 1-4 and Comparative Examples x Medium entropy alloy ingots are tested for hardness. Figure 3 It can be seen that the hardness value increases from 125HV to 582HV. When the addition amount of Y exceeds 0.15, the hardness can reach more than 200HV. When the addition amount of Y exceeds 0.2, the hardness can reach more than 300HV.

[0077] like Figure 4 As shown, the CrFeNi2Y obtained in the above examples 1-3 and the comparative example x The room temperature compression mechanical properties of medium entropy alloy ingots were tested. Figure 4 It can be seen that with the increase of Y content, the yield strength increases from 110MPa to 1265MPa. Specifically, when x=0.15, the yield strength is 420MPa and the compression rate is greater than 45%; when x=0.25, the yield strength is 865MPa and the compression rate is about 24%; when x=0.4, the yield strength is 1265MPa and the compression rate is about 8%. In addition, take the CrFeNi2Y obtained in Example 4 x The medium-entropy alloy ingot was subjected to room temperature compression mechanical property testing, and its fracture strength could reach 1510MPa, but brittle fracture occurred at this time and its plasticity was poor.

[0078] It should be noted that some parts not described in the present invention can be implemented by adopting or drawing on existing technologies.

[0079] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A high performance CrFeNi2Y x Medium entropy alloy, characterized in that The CrFeNi2Y x Medium entropy alloys have a dual-phase structure of FCC and HCP.

2. A high performance CrFeNi2Y according to claim 1 x A method for preparing a medium entropy alloy, characterized in that: Includes steps: (1) Take high-purity Cr, Fe, Ni, and Y single metals as raw materials and pretreat them; (2) Weigh the pretreated Cr, Fe, Ni, and Y single metals in proportion for batching; (3) Melting and casting Cr, Fe, Ni, and Y single metals to obtain CrFeNi2Y x Medium entropy alloy.

3. A high performance CrFeNi2Y according to claim 2 x A method for preparing a medium entropy alloy, characterized in that: The step (1) specifically comprises: firstly immersing the Cr, Fe, Ni, and Y single metals in anhydrous ethanol respectively, and performing ultrasonic cleaning for 1 to 3 times to remove the oxide scale and impurities on the surface of the Cr, Fe, Ni, and Y single metals, and then drying the cleaned single metals and storing them.

4. A high performance CrFeNi2Y according to claim 2 x A method for preparing a medium entropy alloy, characterized in that: The step (2) specifically comprises: firstly, using an electronic balance to weigh Cr, Fe, Ni, and Y single metals in proportion, then respectively immersing the weighed Cr, Fe, Ni, and Y single metals in anhydrous ethanol, using ultrasonic cleaning for 1 to 3 times to remove impurities introduced during the weighing process, and then blowing the cleaned single metals dry and storing them.

5. A high performance CrFeNi2Y according to claim 2 x A method for preparing a medium entropy alloy, characterized in that: The step (3) is specifically as follows: (31) The Cr, Fe, Ni, and Y single metal raw materials weighed in step (2) are placed in a copper crucible in a vacuum melting furnace. At the same time, a pure titanium ingot is placed in another copper crucible in the furnace. The furnace door is then closed and the furnace is evacuated to below 5 Pa. High-purity argon gas is introduced to 0.01-0.05 MPa to wash the furnace 1-3 times. The furnace is then evacuated again to 10 -3 Pa, and high-purity argon gas is introduced to 0.05MPa as protective gas; (32) Arc melting is started. After the arc is started, the pure titanium ingot is first melted for 2 to 3 minutes, and then the Cr, Fe, Ni, and Y single metal raw materials are melted. The arc current is 200A to 250A. After all the raw materials are melted, electromagnetic stirring is turned on. The electromagnetic stirring current is 2 to 3A. After maintaining for 1 to 5 minutes, the alloy liquid is cooled to obtain an initial ingot. (33) Turning the initial ingot over in the copper crucible and melting it again, the arc current is 200A to 250A. After the initial ingot is completely melted, electromagnetic stirring is turned on, the electromagnetic stirring current is 2 to 3A, and after maintaining for 1 to 5 minutes, the alloy liquid is cooled to obtain a secondary ingot. (34) Repeat step (33) 3 to 6 times, and turn off the electromagnetic stirring during the last smelting. After the alloy liquid cools down, CrFeNi2Y x Medium entropy alloy button-shaped ingot; (35) The CrFeNi2Y obtained in step (34) x The medium entropy alloy button-shaped ingot is cast in a rectangular copper mold to obtain CrFeNi2Y x Medium entropy alloy plate ingot.

6. A high performance CrFeNi2Y according to claim 5 x A method for preparing a medium entropy alloy, characterized in that: The step (35) is specifically as follows: firstly, a graphite plate is laid on the bottom of the copper crucible of the flip casting equipment, and then the CrFeNi2Y x The button-shaped ingot of the medium entropy alloy is placed in a copper crucible, the furnace door is closed, and after vacuuming, argon gas is filled to 0.1-0.4 MPa. The arc is turned on to melt the ingot in the copper crucible, and the arc current is 200A-250A. After melting for 80-150s, it is turned over and cast into a rectangular copper mold. After the furnace is naturally cooled, it is taken out to obtain CrFeNi2Y x Medium entropy alloy plate ingot.

7. A high performance CrFeNi2Y according to claim 6 x A method for preparing a medium entropy alloy, characterized in that: In the step (35), the flipping speed during the flip casting process is 90° within 2 seconds, and the natural cooling time after the flip casting is 15 to 20 minutes.

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