Hard magnetic Fe-Co-Pt high-entropy alloy and preparation method thereof

Abstract

The invention discloses a hard magnetic Fe-Co-Pt high-entropy alloy and a preparation method thereof, and belongs to the technical field of new materials. Firstly, a Fe-Co-Pt-X alloy strip is prepared through vacuum arc or induction melting and single-roller melt-spinning, and then a single-phase or complex-phase structure composed of a hard magnetic L10-FePt phase is obtained through vacuum annealing treatment, so that the alloy has the obvious permanent magnetic characteristic. The coercive force of the Fe-Co-Pt high-entropy alloy prepared by the method provided by the invention under a 1.8 T external magnetic field exceeds 104.4 kA / m, and the maximum magnetic energy product ((BH) max) can reach 125.4 kJ / m < 3 >. The hard magnetic high-entropy alloy containing the L10-FePt phase is obtained in a simple electric arc melting and liquid quenching mode. The method fills up the performance blank of high-entropy alloy preparation, and expands the development and application field of hard magnetic materials.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, and in particular to a hard magnetic Fe-Co-Pt high-entropy alloy and its preparation method. Background Technology

[0002] High-entropy alloys, also known as multi-principal-element high-entropy alloys, are novel alloys composed of multiple principal elements. These alloys can be designed as equiatomic or near-equiatomic alloys, where the atomic fraction of each principal element is not necessarily equal, but their content is relatively high (atomic percentage between 5% and 35%). The multi-principal element composition gives the alloy a high mixing entropy, improving the compatibility between the constituent elements. This results in alloys mostly composed of simple body-centered cubic (bcc) or face-centered cubic (fcc) phases, and even nanocrystalline or amorphous structures under casting conditions [MCGao, et al., Springer, 2016]. The combined effect of the multi-principal elements gives high-entropy alloys novel functional properties, and through alloy design, combinations of different functional properties such as high hardness, work-hardening strength, resistivity, ferromagnetism, and resistance to high-temperature softening, oxidation, and corrosion can be obtained [E. Pickering, et al., Int. Mater. Rev. 61 (2016): 183]. Therefore, as an emerging field of materials research, high-entropy alloys have high research value and broad application prospects.

[0003] In recent years, the unique ferromagnetic properties of high-entropy alloys have increasingly attracted attention. Zhang et al. [W. Feng, et al., Metals 7(2017):482; J. Wang, et al., Entropy 20(2018):275.] discovered FeCoNi(AlSi). 0.2 High-entropy alloys have very good comprehensive properties, exhibiting high saturation magnetization and resistivity; high-entropy alloys with good magnetocaloric ability have been prepared by introducing heavy rare earth elements. Qi Tianlong and Xu Yongqiang et al. combined the characteristics of high-entropy and amorphous alloys to prepare Fe-Co-Ni-(C,Si,P,B) series high-entropy amorphous alloys, and pointed out that this series of alloys has excellent soft magnetic properties such as low coercivity, high effective permeability and low iron loss [TLQi, et al., Intermetallics 66(2015):8.]. The applicant also found that soft magnetic nanocrystalline and amorphous alloys that conform to the composition characteristics of high-entropy alloys can be obtained after adding Co to Fe-Pt-B alloys [7]. However, these studies only involve the soft magnetic properties of high-entropy alloys, while the research on the hard magnetic properties of this alloy is still blank.

[0004] The ordered tetragonal (face-centered tetragonal, L10) phases of near-equiatomic Fe-Pt and Co-Pt alloys both exhibit extremely high magnetocrystalline anisotropy, with values ​​of 7 × 10⁻⁶. 3 kJ / m 3 and 5×10 3 kJ / m 3 This material has broad application prospects in functional materials such as ultra-high density magnetic recording and hard magnets [JP Liu, et al., J. Appl. Phys. 81(1997): 5644: S. Sun, Science 287(2000): 1989.]. As shown in the binary alloy phase diagram, the Pt content in the disorder-order phase transformation to form the hard magnetic L10-FePt phase in this type of alloy is approximately 33–59 at.%, which is similar to the composition range of high-entropy alloys with near-equal atomic ratios. Therefore, this application proposes to use near-equal atomic ratio Fe-Co-Pt alloys to prepare hard magnetic high-entropy alloys. This not only provides a new approach for the preparation of magnetic materials but also opens up a new research field for high-entropy alloys. Summary of the Invention

[0005] The purpose of this invention is to provide a hard magnetic Fe-Co-Pt high-entropy alloy and its preparation method to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A hard magnetic Fe-Co-Pt high-entropy alloy, wherein the alloy has a single or multiphase microstructure composed of an L10-FePt ordered phase, and its chemical composition is Fe. a Co b Pt c X d In the formula, X = Ni, Pd, Ti, V, Cr, Mn, Al, Zr, Nb, Hf, Ta, W, B, C, Si or P; a, b, c and d represent the atomic percentages of the corresponding elements, satisfying 10≤a≤65, 0≤b≤45, 10≤c≤40, 0≤d≤40, and a+b+c+d=100.

[0008] As a further aspect of this invention, the high-entropy alloy exhibits significant hard magnetic properties: the coercivity of the high-entropy alloy under an applied magnetic field of 1.8T is 104.4-885.3 kA / m, and the saturation magnetization (M) is... s The remanence (M) ranges from 0.55 to 1.28 T. r The energy product ranges from 0.39 to 1.06 T, and the maximum energy product is (BH). max The highest is 125.4 kJ / m 3 .

[0009] A method for preparing a hard magnetic Fe-Co-Pt high-entropy alloy includes the following steps:

[0010] (1) Prepare Fe-Co-Pt-X master alloy ingots by arc melting or high-frequency induction melting under Ar atmosphere, where X = Ni, Pd, Ti, V, Cr, Mn, Al, Zr, Nb, Hf, Ta, W, B, C, Si or P;

[0011] (2) Amorphous or amorphous / nanocrystalline alloy strips are prepared by single-roller spinning technology, and the strip thickness and phase structure are controlled by the rotation speed of the copper roller;

[0012] (3) Obtain hard magnetic Fe-Co-Pt high entropy alloy with uniformly distributed nano-multiphase components containing hard magnetic L10-FePt and soft magnetic Fe2B by directly obtaining or by vacuum annealing the strip sample.

[0013] A method for preparing a hard magnetic Fe-Co-Pt high-entropy alloy includes the following steps:

[0014] (1) Use Fe, Co, Pt, Ni, Pd, Ti, V, Cr, Mn, Al, Zr, Nb, Hf, Ta, W, B, C, Si raw materials or Fe-P alloys with a purity greater than 99.5wt% according to Fe a Co b Pt c X d (Atomic percentage, 10≤a≤65, 0≤b≤45, 10≤c≤40, 0≤d≤40, and a+b+c+d=100) The nominal components are weighed and batched.

[0015] (2) Alloys containing P or C elements are prepared into master alloy ingots by high-frequency induction melting in an Ar atmosphere. Other alloys are prepared into master alloy ingots by non-consumable electric arc furnace in an Ar atmosphere. The alloys are repeatedly melted four times to ensure uniform composition. The master alloy ingots are made into continuous alloy strip samples with a width of about 2 mm and a thickness of about 10 to 50 μm by single-roller strip spinning equipment in an Ar atmosphere. The strip thickness is controlled by the rotation speed of the copper roller.

[0016] (3) Detect the structure and thermal properties of the alloy strip samples prepared at different copper roller speeds; combine the structure and thermal properties analysis to determine the heat treatment temperature of the alloy strip; if the alloy strip contains hard magnetic L10-FePt and soft magnetic Fe2B nano-composite structure, then directly implement step (5); otherwise implement step (4).

[0017] (4) The alloy strip was annealed by vacuum heat treatment to obtain a strip precursor containing a hard magnetic L10-FePt and a soft magnetic Fe2B nano-multiphase structure;

[0018] (5) The obtained alloy strips were characterized in structure and tested in magnetic properties;

[0019] The structure of the samples before and after heat treatment was characterized by X-ray diffraction and high-resolution transmission electron microscopy; the alloy composition distribution was determined by energy dispersive spectroscopy; the thermal properties of the strip samples were detected by differential scanning calorimetry; and the magnetic properties of the alloy samples before and after heat treatment were tested using a vibrating sample magnetometer.

[0020] Compared with existing technologies, this invention has the following advantages: This invention obtains a hard magnetic high-entropy alloy containing the L10-FePt phase through simple electric arc melting and liquid rapid cooling. This invention fills the performance gap in the preparation of high-entropy alloys and expands the development and application fields of hard magnetic materials. Attached Figure Description

[0021] Figure 1 The Fe of this invention is annealed at 823K for 900s. 25 Co 25 Pt 25 B 25 X-ray diffraction pattern of alloy strips.

[0022] Figure 2 The Fe of this invention is annealed at 823K for 900s. 25 Co 25 Pt 25 B 25 Transmission electron microscope images and selected area electron diffraction images of the alloy.

[0023] Figure 3 The Fe of this invention is annealed at 823K for 900s. 25 Co 25 Pt 25 B 25 Hysteresis loop diagram of the alloy. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0025] Example 1

[0026] Now, with the component being Fe... 25 Co 25 Pt 25 B 25 Taking the alloy as an example, the implementation methods for the preparation and performance testing of hard magnetic Fe-Co-Pt high-entropy alloys are described in detail with reference to the accompanying drawings.

[0027] Step 1: Prepare the ingredients;

[0028] High-purity Fe (99.9 wt.%), Co (99.9 wt.%), Pt (99.95 wt.%) and B (99.5 wt.%) raw materials were selected and processed according to Fe... 25 Co 25 Pt 25 B 25 The ingredients are weighed and dispensed.

[0029] Step 2: Alloy ingot smelting;

[0030] The weighed metal raw material is placed into the water-cooled copper crucible of the electric arc melting furnace, and a vacuum of 3×10⁻⁶ is drawn. -3 Pa, then an appropriate amount of argon gas was introduced, and the alloy was smelted. After smelting, the alloy ingot was flipped over and smelted repeatedly four times to obtain Fe with uniform composition. 25 Co 25 Pt 25 B 25 Alloy ingots;

[0031] Step 3: Preparation of rapidly cooled strip samples;

[0032] After the alloy ingot is crushed, it is placed into a quartz tube with a nozzle diameter of approximately 0.5 mm, and then placed inside an induction heating coil. Using liquid quenching technology under argon protection, the alloy sample is melted and sprayed onto a high-speed rotating copper roller to prepare Fe. 25 Co 25 Pt 25 B 25 Alloy strip sample. The strip spinning speed is about 40 m / s, the width of the alloy strip is about 1-2 mm, and the thickness is about 20 μm.

[0033] Step 4: Microstructure analysis of the alloy strip;

[0034] The structure of the quenched strip alloy was analyzed by X-ray diffraction (XRD) (Cu-Kα radiation, λ = 0.15406 nm).

[0035] Step 5: Vacuum annealing;

[0036] The alloy strip was placed in a quartz tube with an inner diameter of 6 mm and a wall thickness of 1 mm, and the vacuum was reduced to 2 × 10⁻⁶. -3 The sample was sealed below Pa, and then placed in an annealing furnace for isothermal annealing at an appropriate temperature for 900s. It was then removed and water-quenched.

[0037] Step Six: Measurement of the microstructure and magnetic properties of the annealed sample;

[0038] The microstructure of the annealed samples was analyzed by XRD and TEM. Figure 1 The XRD pattern shows that the annealed sample consists of a hard magnetic L10-FePt phase and a soft magnetic Fe2B phase. Figure 2 The TEM images show that the sample has uniform grains with a size of about 30 nm, and the selected area diffraction pattern is consistent with the XRD results. Figure 3 This is the hysteresis loop of the high-entropy alloy under an external magnetic field of 1.8T, indicating that the alloy possesses excellent hard magnetic properties. At an annealing temperature of 823K, the alloy's coercivity ( i H c ), saturation magnetization (M) s ), remanence (M) r ) and the maximum magnetic energy product ((BH) max The values ​​are: 746.2 kA / m, 0.67 T, 0.51 T, and 42.0 kJ / m, respectively. 3 When the annealing temperature is 863K, the corresponding values ​​are: 885.3 kA / m, 0.61 T, 0.46 T, and 34.8 kJ / m. 3 .

[0039] Example 2

[0040] The component is Fe 30 Co 30 Pt 40 High-entropy alloys;

[0041] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 423.7 kA / m, 0.57 T, 0.42 T, and 25.3 kJ / m, respectively. 3 .

[0042] Example 3

[0043] The component is Fe 65 Pt 15 B 20 High-entropy alloys;

[0044] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max They are: 104.4 kA / m, 1.24 T, 1.08 T, and 41.8 kJ / m, respectively. 3 .

[0045] Example 4

[0046] The component is Fe 50 Pt 25 B 25 High-entropy alloys;

[0047] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 806.7 kA / m, 0.90 T, 0.68 T, and 53.8 kJ / m, respectively. 3 .

[0048] Example 5

[0049] The component is Fe 35 Pt 30 B 35 High-entropy alloys;

[0050] The specific implementation steps are the same as in Example 1, except that the belt-spinning speed during the single-roller belt-spinning process is adjusted to 45 m / s, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 198.9 kA / m, 0.55 T, 0.39 T, and 21.5 kJ / m, respectively. 3 .

[0051] Example 6

[0052] The component is Fe 50 Pt 10 B 40 High-entropy alloys;

[0053] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 124.4 kA / m, 0.94 T, 0.60 T, and 22.3 kJ / m, respectively. 3 .

[0054] Example 7

[0055] The component is Fe 40 Co 20 Pt 20 B 20 High-entropy alloys;

[0056] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) maxThe values ​​are: 348.9 kA / m, 0.91 T, 0.73 T, and 66.3 kJ / m, respectively. 3 .

[0057] Example 8

[0058] The component is Fe 40 Co 20 Pt 15 B 25 High-entropy alloys;

[0059] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 310.6 kA / m, 1.09 T, 0.88 T, and 75.2 kJ / m, respectively. 3 .

[0060] Example 9

[0061] The component is Fe 50 Co5Pt 20 B 25 High-entropy alloys;

[0062] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 438.7 kA / m, 1.28 T, 1.06 T, and 125.4 kJ / m, respectively. 3 .

[0063] Example 10

[0064] The component is Fe 40 Co 20 Pt 10 B 30 High-entropy alloys;

[0065] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 182.6 kA / m, 1.11 T, 0.92 T, and 72.0 kJ / m, respectively. 3 .

[0066] Example 11

[0067] The component is Fe 10 Co45 Pt 15 B 30 High-entropy alloys;

[0068] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 190.1 kA / m, 0.67 T, 0.50 T, and 29.2 kJ / m, respectively. 3 .

[0069] Example 12

[0070] The component is Fe 40 Co5Pt 20 B 35 High-entropy alloys;

[0071] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 123.9 kA / m, 0.70 T, 0.47 T, and 15.9 kJ / m, respectively. 3 .

[0072] Example 13

[0073] The precursor alloy is Fe 35 Co 10 Pt 15 B 40 quenching strip;

[0074] The specific implementation steps are the same as in Example 1, but P element is added during the batching process using Fe3P master alloy, and alloy ingots are prepared using induction melting. The strip casting speed is adjusted to 60m / s, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 254.9 kA / m, 1.03 T, 0.78 T, and 58.5 kJ / m, respectively. 3 .

[0075] Example 14

[0076] The component is Fe 35 Co 20 Pt 20 B 20 High-entropy alloy of Ni5;

[0077] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 368.5 kA / m, 0.74 T, 0.62 T, and 39.8 kJ / m, respectively. 3 .

[0078] Example 15

[0079] The component is Fe 20 Co 20 Pt 20 B 20 Ni 20 High-entropy alloys;

[0080] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 257.9 kA / m, 0.76 T, 0.53 T, and 24.5 kJ / m, respectively. 3 .

[0081] Example 16

[0082] The precursor alloy is Fe 45 Co 10 Pt 25 B 15 Si5’s quench strip;

[0083] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 352.7 kA / m, 1.07 T, 0.83 T, and 72.8 kJ / m, respectively. 3 .

[0084] Example 17

[0085] The component is Fe 25 Co 25 Pt 20 B 10 P 10 High-entropy alloys;

[0086] The alloy ingot was prepared using induction melting, and the addition of phosphorus (P) was achieved using a Fe3P binary alloy during the batching process. Other steps were the same as in Example 1. The final alloy obtained... i H c Ms M r and (BH) max The values ​​are: 579.6 kA / m, 0.71 T, 0.51 T, and 38.4 kJ / m, respectively. 3 .

[0087] Example 18

[0088] The component is Fe 40 Co 15 Pt 20 B 25 W3 high-entropy alloy;

[0089] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 467.5 kA / m, 0.73 T, 0.53 T, and 42.8 kJ / m, respectively. 3 .

[0090] Example 19

[0091] ComponentFe 40 Co 15 Pt 15 B 27 High-entropy alloys of Nb3;

[0092] The specific implementation steps are the same as in Example 1, and the final alloy obtained is... i H c M s M r and (BH) max The values ​​are: 275.9 kA / m, 1.16 T, 0.97 T, and 94.0 kJ / m, respectively. 3 .

[0093] Example 20

[0094] The component is Fe 45 Co 10 Pt 15 Pd 10 B 18 C2 high-entropy alloy;

[0095] The specific implementation steps are the same as in Example 1, but induction melting is used to prepare the alloy ingot, and the belt speed during the single-roller belt spinning process is adjusted to 50 m / s, resulting in a higher alloy content. i H c M s M r and (BH) maxThe values ​​are: 379.1 kA / m, 0.92 T, 0.69 T, ​​and 45.6 kJ / m, respectively. 3 .

[0096] Example 21

[0097] The component is Fe 45 Co 10 Pt 15 Pd 10 B 15 High-entropy alloys of Al5;

[0098] The specific implementation steps are the same as in Example 1, but induction melting is used to prepare the alloy ingot, and the belt speed during the single-roller belt spinning process is adjusted to 50 m / s, resulting in a higher alloy content. i H c M s M r and (BH) max The values ​​are: 289.1 kA / m, 0.94 T, 0.70 T, and 44.6 kJ / m, respectively. 3 .

[0099] The magnetic properties of Examples 1-20 are summarized in Table 1 below; the composition and magnetic properties of some hard magnetic high-entropy alloys disclosed in this invention are as follows, i H c M s M r and (BH) max These are coercivity, saturation magnetization, remanence, and maximum energy product, respectively.

[0100]

[0101]

[0102] The high-entropy alloy obtained by the preparation method provided in this invention exhibits more pronounced hard magnetic properties, with a coercivity in the range of 104.4-885.3 kA / m.

[0103] The above description represents a preferred embodiment of the present invention. For those skilled in the art, any changes, modifications, substitutions, and variations made to the implementation methods without departing from the principles and spirit of the present invention, based on the teachings of the present invention, still fall within the protection scope of the present invention.

Claims

1. A hard magnetic Fe-Co-Pt high-entropy alloy, characterized in that, The alloy has a single or multiphase microstructure composed of L10-FePt ordered phases, and its chemical composition is Fe. a Co b Pt c X d In the formula, X = Ni, Pd, Ti, V, Cr, Mn, Al, Zr, Nb, Hf, Ta, W, B, C, Si or P; a, b, c and d represent the atomic percentages of the corresponding elements, satisfying 10≤a≤65, 0≤b≤45, 10≤c≤40, 0≤d≤40, and a+b+c+d=100.

2. The hard magnetic Fe-Co-Pt high-entropy alloy according to claim 1, characterized in that, High-entropy alloys exhibit significant hard magnetic properties: the coercivity of high-entropy alloys under an applied magnetic field of 1.8T is 104.4-885.3 kA / m, and the saturation magnetization (M) is... s The remanence (M) ranges from 0.55 to 1.28 T. r The energy product ranges from 0.39 to 1.06 T, and the maximum energy product is (BH). max The highest is 125.4 kJ / m 3 .

3. The method for preparing a hard magnetic Fe-Co-Pt high-entropy alloy as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Prepare Fe-Co-Pt-X master alloy ingots by arc melting or high-frequency induction melting under Ar atmosphere, where X = Ni, Pd, Ti, V, Cr, Mn, Al, Zr, Nb, Hf, Ta, W, B, C, Si or P; (2) Amorphous or amorphous / nanocrystalline alloy strips are prepared by single-roller spinning technology, and the strip thickness and phase structure are controlled by the rotation speed of the copper roller; (3) Obtain hard magnetic Fe-Co-Pt high entropy alloy with uniformly distributed nano-multiphase components containing hard magnetic L10-FePt and soft magnetic Fe2B by directly obtaining or by vacuum annealing the strip sample.

4. The method for preparing a hard magnetic Fe-Co-Pt high-entropy alloy as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Use Fe, Co, Pt, Ni, Pd, Ti, V, Cr, Mn, Al, Zr, Nb, Hf, Ta, W, B, C, Si raw materials or Fe-P alloys with a purity greater than 99.5wt% according to Fe a Co b Pt c X d (Atomic percentage, 10≤a≤65, 0≤b≤45, 10≤c≤40, 0≤d≤40, and a+b+c+d=100) The nominal components are weighed and batched. (2) Alloys containing P or C elements are prepared into master alloy ingots by high-frequency induction melting in an Ar atmosphere. Other alloys are prepared into master alloy ingots by non-consumable electric arc furnace in an Ar atmosphere. The alloys are repeatedly melted four times to ensure uniform composition. The master alloy ingots are made into continuous alloy strip samples with a width of about 2 mm and a thickness of about 10 to 50 μm by single-roller strip spinning equipment in an Ar atmosphere. The strip thickness is controlled by the rotation speed of the copper roller. (3) Detect the structure and thermal properties of alloy strip samples prepared at different copper roller speeds; combine the structural and thermal property analysis to determine the heat treatment temperature of the alloy strip; If the alloy strip contains a hard magnetic L10-FePt and a soft magnetic Fe2B nanocomposite structure, then proceed directly to step (5); otherwise proceed to step (4). (4) The alloy strip was annealed by vacuum heat treatment to obtain a strip precursor containing a hard magnetic L10-FePt and a soft magnetic Fe2B nano-multiphase structure; (5) The obtained alloy strips were characterized by their structure and tested for their magnetic properties; The structure of the samples before and after heat treatment was characterized by X-ray diffraction and high-resolution transmission electron microscopy; the alloy composition distribution was determined by energy dispersive spectroscopy; the thermal properties of the strip samples were detected by differential scanning calorimetry; and the magnetic properties of the alloy samples before and after heat treatment were tested using a vibrating sample magnetometer.

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