A kind of iron-based amorphous alloy magnetic refrigeration composite material and preparation method thereof

Abstract

The invention discloses an iron-based amorphous alloy magnetic refrigeration composite material, wherein the refrigeration composite material is partially replaced by heavy rare earth elements. 89 Iron-based amorphous alloy strips and Fe 89 Zr7B4 amorphous alloy strips are composited, and the heavy rare earth element is one of Dy, Tb, and Gd; the heavy rare earth element is replaced to effectively increase the Fe 89 The amorphous forming ability of Zr7B4 alloy, the Curie temperature of these materials is close to room temperature, the Curie temperature T c The range is increased to 275K~342K, which can take into account both the magnetic entropy change and the half-width of the magnetic entropy change.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic refrigeration materials, and in particular to an iron-based amorphous alloy magnetic refrigeration composite material and a preparation method thereof. Background Art

[0002] At present, the traditional vapor compression / expansion refrigeration technology has aggravated the ozone layer depletion and greenhouse effect due to the use of fluorinated refrigerants. At the same time, magnetic refrigeration (MR) based on magnetocaloric effect (MCE) has unique advantages such as low power consumption, high efficiency, quiet operation, good reliability, and miniaturization, and has become a hot topic of research in countries around the world. The MCE performance of refrigeration materials, as a basic concept of MR, directly determines its heat exchange capacity and refrigeration efficiency. Therefore, how to obtain new refrigerants with excellent MCE performance is a fundamental problem that exists at present. So far, a large number of giant MCE alloys and compounds with first-order magnetic phase transition (FOMPT) have been developed, because the extremely high peak value of magnetic entropy change (-ΔSpeak m) provides great advantages for magnetic refrigeration materials. However, the operating temperature range is narrow, usually around 15K, making it difficult to meet the requirements of Ericsson cycle under a wider temperature range. The second-order magnetic phase transition (SOMPT) MCE materials represented by amorphous alloys have a high magnetic entropy change (-ΔSpeak m) due to their high magnetic entropy change (-ΔSpeak m). m ) curve is wider and more suitable for Ericsson cycle refrigeration. In addition, amorphous alloys have a wide range of composition adjustment, excellent mechanical properties, and a Curie temperature (T c ), negligible hysteresis, high resistivity, and excellent corrosion resistance due to the long-range disordered atomic structure, all of which provide more advantages for MCE materials. However, achieving an ideal refrigeration process requires MCE materials to maintain a large -ΔSpeak m value over a wide temperature range. More specifically, a constant or plateau-type -ΔSpeak m curve that changes with temperature, the so-called "platform-type" MCE, is more desirable. Although most of the SOMPT MCE rare earth-based materials currently studied show a large operating temperature range and a wide magnetic entropy change "platform", they are relatively expensive. Therefore, it is very necessary to design non-precious metal MCE materials with a large operating temperature range and a wide magnetic entropy change "platform". Summary of the invention

[0003] In view of this, the object of the present invention is to provide an iron-based amorphous alloy magnetic refrigeration composite material and a preparation method thereof, which can maintain a large -ΔSpeak m value under a large operating temperature range, and the maximum entropy change value is not less than 3J·kg under a 5T magnetic field change. -1 ·K -1 , the half-width of magnetic entropy change is not less than 100K.

[0004] The iron-based amorphous alloy magnetic refrigeration composite material of the present invention is composed of a heavy rare earth element partially replacing Fe 89 Iron-based amorphous alloy strips and Fe 89 The heavy rare earth element is one of Dy, Tb and Gd;

[0005] Further, at least one Fe-based amorphous alloy strip is combined with Fe 89 The Zr7B4 amorphous alloy strips were glued together by non-magnetic tape to obtain an iron-based amorphous alloy magnetic refrigeration composite material;

[0006] Furthermore, the chemical formula of the iron-based amorphous alloy strip is Fe 87 Zr7B4RE2, wherein RE is one of Dy, Tb, and Gd;

[0007] Furthermore, the mass fractions of the components in the iron-based amorphous alloy magnetic refrigeration composite material are 42.5wt% (Fe 89 Zr7B4), 5wt%(Fe 87 Zr7B4Dy2), 2.5wt.%Fe 87 Zr7B4Tb2 and 50wt.%(Fe 87 Zr7B4Gd2);

[0008] Furthermore, the mass fractions of the components in the iron-based amorphous alloy magnetic refrigeration composite material are 50wt.% (Fe 87 Zr7B4Tb2) and 50wt.% (Fe 87 Zr7B4Gd2).

[0009] The present invention also discloses a method for preparing an iron-based amorphous alloy magnetic refrigeration composite material, comprising the following steps:

[0010] a. Melt the single element raw materials under the protection of high-purity inert gas argon to prepare the master alloy and remove the surface oxide;

[0011] b. The prepared master alloy is subjected to a single-roll strip spinning method in an induction furnace to obtain Fe-based amorphous alloy strips.

[0012] c. Prepare Fe 87 Zr7B4RE2 amorphous alloy strip and original Fe 89 The Zr7B4 amorphous alloy strips are glued together by non-magnetic tape;

[0013] Further, in step a, surface oxides are removed by grinding the surfaces of the element and the master alloy;

[0014] Furthermore, in step a, the purity of the single substance is not less than 99.9%.

[0015] Furthermore, in step b, the amorphous alloy strip has a thickness of 30 to 50 μm and a width of 3 to 5 mm; further, in step b, the tangential speed of the roller of the single-roller strip spinning machine is 40 m / s.

[0016] The beneficial effects of the present invention are as follows: the iron-based amorphous alloy magnetic refrigeration material and preparation method disclosed in the present invention effectively improves Fe by replacing heavy rare earth elements (Dy, Tb, Gd). 89 The amorphous forming ability of Zr7B4 alloy, the Curie temperature of these materials is close to room temperature, the Curie temperature T c The range is increased to 275K~342K, which can take into account both the magnetic entropy change and the half-width of the magnetic entropy change.

[0017] The material has a large magnetic entropy change and a wide half-width of magnetic entropy change under an external magnetic field of 0-5T. c ) is close to room temperature, and the Curie temperature range is 275K~342K, which can take into account both the magnetic entropy change and the half-width of the magnetic entropy change. The Curie temperature of the amorphous alloy system rises from 275K to 342K. Under an external magnetic field of 5T, the addition of heavy rare earth does not significantly change the Fe 89 The magnetic entropy change peak value of Zr7B4 alloy. Then the present invention partially replaces Fe with Dy, Tb, and Gd. 89 The amorphous alloy strip after Zr7B4 and the original Fe 89 The Fe strips in the Zr7B4 amorphous alloy were glued together by non-magnetic tape to obtain the Fe-based amorphous alloy magnetic refrigeration composite material. A potential amorphous composite material with a "platform-type" magnetic entropy change curve at different temperatures was designed. The "platform" of composite material #2 was 20K, and the magnetic entropy change "platform" was about 3.04J·kg -1 ·K -1 Its magnetic entropy change value exceeds that of most iron-based amorphous composite materials and is closer to the ΔT of rare earth-based amorphous alloy composite materials. plat Value, near room temperature is ΔT plat This material is expected to become an effective room-temperature magnetic refrigeration material in refrigeration equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0019] Figure 1 The Fe 89 XRD spectrum of Zr7B4 amorphous alloy with appropriate amount of rare earth elements (Dy, Tb, Gd) replacing part of Fe;

[0020] Figure 2 The Fe89 DSC curve of adding appropriate amount of heavy rare earth elements (RE = Dy, Tb, Gd) to replace part of Fe in Zr7B4 amorphous alloy;

[0021] Figure 3 The Fe 89 MT curve of adding appropriate amount of heavy rare earth elements (RE=Dy, Tb, Gd) to replace part of Fe in Zr7B4 amorphous alloy;

[0022] Figure 4 The Fe 89 MH curve and Arrott curve of adding appropriate amount of heavy rare earth elements (RE=Dy, Tb, Gd) to replace part of Fe in Zr7B4 amorphous alloy;

[0023] Figure 5 The Fe 89 Temperature dependence curve of magnetic entropy change under different magnetic fields when adding appropriate amount of heavy rare earth elements (RE=Dy, Tb, Gd) to Zr7B4 amorphous alloy to replace part of Fe.

[0024] Figure 6 -ΔS of composite material #1, composite material #2 and Fe-Zr-B based amorphous composite material samples under 5T magnetic field m -T curve. DETAILED DESCRIPTION

[0025] The iron-based amorphous alloy magnetic refrigeration material of this embodiment is an iron-based amorphous alloy magnetic refrigeration material Fe 87 Zr7B4RE2 (RE = Dy, Tb, Gd), the preparation method is as follows:

[0026] a. According to the chemical formula of the iron-based magnetic refrigeration material, Fe 87 Zr7B4RE2 (RE = Dy, Tb, Gd) raw materials: Place the components (the purity of the single substance is not less than 99.9%) in the crucible of a non-consumable vacuum arc furnace (placed from top to bottom in order of melting point). At the same time, put titanium sponge in one of the crucibles. Then use a mechanical pump to evacuate to 0.1Pa, then fill it with high-purity argon to 0.05MPa, and finally use a molecular pump to evacuate to 3.2×10 -4 Pa, and then fill with argon gas 0.05MPa. Turn on the power, first melt the titanium sponge for about 15s, then melt the sample immediately for about 20s, cool it for 1min, turn the sample over, and repeat the melting again. Melt the sample 4-6 times cumulatively to obtain the master alloy ingot; grind the molten surface of the master alloy to remove the surface oxide;

[0027] b. The master alloy ingot is placed in a quartz tube with a small hole above the single-roller belt spinning machine, and then vacuumed to 0.1Pa by a mechanical pump, and then filled with high-purity argon gas to 0.05MPa, and then vacuumed to 3.2×10 -4 Pa, and then filled with argon gas 0.05MPa. Finally, turn on the power, and the tangential speed of the single-roller belt-spinning machine is 40m / s. When the master alloy is in a molten state and just drips, turn on the power switch, use the pressure difference to spray the molten alloy onto the roller and cool it quickly, and Fe 87 Zr7B4RE2 (RE=Dy, Tb, Gd) amorphous alloy strip.

[0028] c. Partially replace Fe with Dy, Tb, and Gd 89 The amorphous alloy strips of Fe in Zr7B4 and the original Fe 89 The Zr7B4 amorphous alloy strips were glued together by non-magnetic tape to obtain an iron-based amorphous alloy magnetic refrigeration composite material. The mass fractions of the components in composite material #1 were 42.5wt% (Fe 89 Zr7B4), 5wt%(Fe 87 Zr7B4Dy2), 2.5wt.%Fe 87 Zr7B4Tb2,50wt.%(Fe 87 Zr7B4Gd2), the mass fraction ratio of each component of composite material #2 is 50wt.%(Fe 87 Zr7B4Tb2), 50wt.%(Fe 87 Zr7B4Gd2). Its calculation method is:

[0029]

[0030] where ω i is the mass fraction of amorphous ribbon

[0031] The phase analysis of the samples prepared above is as follows:

[0032] The X-ray diffraction (XRD) pattern of the material is measured using an X-ray diffractometer. Figure 1 As shown, Fe 89 Zr7B4 and Fe 87 The XRD spectrum of the Zr7B4RE2 (RE = Dy, Tb, Gd) strip shows a broad halo between 40° and 50°, and typical amorphous diffuse scattering peaks without sharp crystalline peaks indicate the amorphous structure of the alloy.

[0033] Fe 87 The DSC curve of Zr7B4RE2 (RE = Dy, Tb, Gd) was measured by differential scanning calorimetry (DSC). Figure 2 As shown, Fe89 Zr7B4 and Fe 87 The DSC curves of the Zr7B4RE2 (RE = Dy, Tb, Gd) spinning ribbons show typical endothermic behavior, which is due to the obvious glass transition before the sharp crystallization exothermic peak during heating, further confirming the amorphous characteristics of the alloy. In addition, Table 1 summarizes the thermodynamic parameters, including the glass transition temperature (T g ), crystallization temperature (T x ), melting temperature (T m ), liquidus temperature (T l ), the calculated subcooled liquid temperature (ΔT x =T x -T g ), parameter γ(γ=T x / (T g +T m )) and the theoretical critical section thickness (Z c =2.8×10 -7exp(41.7γ) )value.

[0034] Table 1 Fe 89 Zr7B4 and Fe 87 Thermodynamic parameters of Zr7B4RE2 (RE=Dy, Tb, Gd) amorphous alloy ribbons

[0035]

[0036] with Fe 89 Compared with Zr7B4 amorphous alloy strips, Fe 87 ΔT of Zr7B4RE2 (RE=Dy, Tb, Gd) amorphous alloy strip x , γ and Z c The results show that in Fe 89 Adding 2 at.% of heavy rare earth elements to the Zr7B4 ternary alloy can improve the glass forming ability (GFA) of the alloy.

[0037] The performance tests of the above-mentioned samples obtained are as follows:

[0038] Figure 3 Drawn Fe 89 Zr7B4 and Fe 87 The curve of magnetization intensity (MT) of Zr7B4RE2 (RE=Dy, Tb, Gd) amorphous material changing with temperature. All MT curves are at Curie temperature (T c ) drops sharply, from Figure 3 It can be seen that the Fe estimated from the MT curve 89 Zr7B4 T c About 275K,Fe87 Zr7B4Dy2 is about 308K, Fe 87 Zr7B4Tb2 is about 319K, Fe 87 Zr7B4Gd2 is about 342K. This shows that the addition of heavy rare earth elements increases the T of the alloy system. c In particular, the addition of Gd increases T c In the Fe-Zr-B-RE system of the present invention, T c The increase in T is due to the addition of RE elements, which enhances the Fe-Fe interaction. The newly introduced RE-Fe interaction and the enhanced Fe-Fe interaction make the alloy T c It shows an increasing trend with the addition of RE.

[0039] Figure 4 (a)-(d) plotted Fe 89 Zr7B4 and Fe 87 Isothermal magnetization curve of Zr7B4RE2 (RE = Dy, Tb, Gd) amorphous alloy sample. Here, the sample is below T c The alloy is rapidly magnetized at a temperature of c Above this point, the MH curve gradually changes from ferromagnetism to paramagnetism. 2 -H / M) diagram (converted from Mh curve, such as Figure 4 (e)-(h)), the type of magnetic entropy change of the alloy can be determined. The positive slope of the Arrott diagram at different temperatures indicates that the alloy undergoes a second-order ferromagnetic-paramagnetic transition during heating. This not only allows the alloy to undergo continuous phase transformation over a wide temperature range, but also gives the alloy a comprehensive cooling ability.

[0040] Figure 5 Fe 89 Zr7B4 and Fe 87 -ΔS of Zr7B4RE2 (RE=Dy, Tb, Gd) samples under different electric fields m -T temperature dependence curve. Isotherm -ΔS m It can be calculated using Maxwell's relations:

[0041]

[0042] -ΔS m The wide temperature range confirms the SOMPT properties of the material, which are summarized in Table 2. Figure 5 -ΔS m peak value.

[0043] Table 2 Fe 89Zr7B4 and Fe 87 T of Zr7B4RE2 (RE=Dy,Tb,Gd) amorphous alloy strip c and -ΔS m peak value

[0044]

[0045] After adding Tb and Gd, the -ΔSpeak m of the amorphous alloy is enhanced, which is due to the increase in the angular momentum of the system after adding Tb or Gd. 89 Compared with Zr7B4 amorphous alloy, the -ΔSpeak m of Dy addition is enhanced only at low magnetic fields below 3T, while -ΔSpeak m is weakened at strong magnetic fields. This special trend is related to the non-collinear antiferromagnetic interaction between Dy and Fe, which leads to the multiferromagnetic (MF) transition under strong magnetic fields. The strong interaction between short-range ordered multiferromagnetic phases suppresses the free rotation of magnetic moments, thus affecting the MCE of the alloy under high fields. Fe 87 Zr7B4Dy2、Fe 87 Zr7B4Tb2 and Fe 87 The -ΔSpeak m values ​​of Zr7B4Gd2 samples under 5T magnetic field are about 3.14 J·kg -1 ·K -1 , 3.25 J·kg -1 ·K -1 and 3.24 J·kg -1 ·K -1 Compared with other Fe-Zr-B based amorphous alloys, Fe 87 The Zr7B4RE2 (RE=Dy, Tb, Gd) amorphous alloy has a higher -ΔSpeak m value, indicating that Fe 87 Zr7B4RE2 (RE = Dy, Tb, Gd) amorphous alloy has potential application prospects as a room temperature MR material. 87 The strong amorphous forming ability of Zr7B4RE2 (RE=Dy, Tb, Gd) amorphous alloy makes it easier to process and form, which is beneficial to its application.

[0046] Figure 6 The -ΔS of composite material #1, composite material #2 and Fe-Zr-B based amorphous composite material samples under 5T magnetic field are given. m -T curve. Composite material #1 has a large temperature range, from near the melting point temperature (278K) to the hot end of magnetic refrigeration (340K), and in the platform temperature range (ΔT plat )The platform value of magnetic entropy change (-ΔSplatm) is 2.60 J·kg -1 ·K-1 to 2.67 J·kg -1 ·K -1 ΔT of composite material #2 plat is about 20K, and -ΔSplatm is about 3.04J·kg -1 ·K -1 . Compared with Fe-Zr-B based amorphous composite materials (-ΔSplatm~2.91J·kg -1 ·K -1 , ΔT plat ~40K), the platform temperature range of composite material #1 increases and the -ΔSplatm value decreases. For composite material #2, although its ΔT plat Only at 20K, -ΔSplat m increases to more than 3 J·kg -1 ·K -1 Its magnetic entropy change value exceeds that of most iron-based amorphous composite materials, and ΔT plat The prepared amorphous alloys and composite materials have strong properties, providing a useful potential material system for further broadening the performance of iron-based amorphous materials. This material is expected to become an effective room-temperature magnetic refrigeration material in refrigeration equipment.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. An iron-based amorphous alloy magnetic refrigeration composite material, Features: The refrigeration composite material is partially replaced by heavy rare earth elements. 89 Zr 7 B 4 Iron-based amorphous alloy strips and Fe 89 Zr 7 B 4 The amorphous alloy strips are composited, wherein the heavy rare earth element is Dy, Tb or Gd; at least one iron-based amorphous alloy strip is composited with Fe 89 Zr 7 B 4 The amorphous alloy strips are glued together by non-magnetic tape to obtain an iron-based amorphous alloy magnetic refrigeration composite material. The chemical formula of the iron-based amorphous alloy strips is Fe 87 Zr 7 B 4 RE 2 , wherein RE is Dy, Tb or Gd; the iron-based amorphous alloy magnetic refrigeration composite material is Fe 89 Zr 7 B 4 , Fe 87 Zr 7 B 4 Dy 2 , Fe 87 Zr 7 B 4 Tb 2 and Fe 87 Zr 7 B 4 G 2 The composites have a mass fraction of 42.5 wt%Fe 89 Zr 7 B 4 、5wt% Fe 87 Zr 7 B 4 Dy 2 、2.5 wt.% Fe 87 Zr 7 B 4 Tb 2 and 50 wt.% Fe 87 Zr 7 B 4 G 2 .

2. The method for preparing the iron-based amorphous alloy magnetic refrigeration composite material according to claim 1, Features: The following steps are involved: The single element raw materials are melted under the protection of high-purity inert gas argon to prepare the master alloy and remove the surface oxides; The prepared master alloy was subjected to a single-roll strip-throwing method in an induction furnace to obtain a Fe-based amorphous alloy strip; The prepared Fe 87 Zr 7 B 4 RE 2 Amorphous alloy strip and original Fe 89 Zr 7 B 4 The amorphous alloy strips are glued together by non-magnetic tape.

3. The method for preparing the iron-based amorphous alloy magnetic refrigeration composite material according to claim 2, Features: In step a, surface oxides are removed by grinding the surfaces of the element and the master alloy.

4. The method for preparing the iron-based amorphous alloy magnetic refrigeration composite material according to claim 2, Features: In step a, the purity of the single substance is not less than 99.9%.

5. The method for preparing the iron-based amorphous alloy magnetic refrigeration composite material according to claim 4, Features: In step b, the amorphous alloy strip has a thickness of 30-50 μm and a width of 3-5 mm.

6. The method for preparing the iron-based amorphous alloy magnetic refrigeration composite material according to claim 5, Features: In step b, the tangential speed of the roller of the single-roller belt-spinning machine is 40 m / s.

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