La-Fe-Si-based composite material with good plastic deformation performance and preparation method of La-Fe-Si-based composite material

Abstract

The invention discloses a preparation method of a La-Fe-Si-based composite material with good plastic deformation performance, which comprises the following steps: uniformly mixing La-Fe-Si-based magnetic refrigeration material powder and micron-sized Fe-Ni alloy material powder, and carrying out high-temperature discharge plasma sintering molding to prepare a magnetic refrigeration block material; the La-Fe-Si-based magnetic refrigeration material is a La < 1.0 > Cex (Fe < 1-y > Coy) < 13-z > Siz compound, wherein x is greater than or equal to 0.1 and less than or equal to 0.3, y is greater than or equal to 0.01 and less than or equal to 0.08, z is greater than or equal to 1.0 and less than or equal to 1.6, and the particle size is less than or equal to 90 microns. The preparation method effectively solves the problems that the La-Fe-Si material is poor in processing formability and difficult to consider the magnetocaloric-mechanical synergistic performance. And meanwhile, the process integration level is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of magnetic functional material preparation technology, specifically relating to a method for preparing high-performance La-Fe-Si based magnetic refrigeration composite materials by SPS technology and achieving synergistic regulation of their mechanical properties and magnetocaloric effects through thermal decomposition and annealing treatment. Background Technology

[0002] Refrigeration technology is an indispensable foundation for modern industry, commerce, and daily life. However, the currently dominant gas compression refrigeration technology relies on refrigerants such as chlorofluorocarbons (CFCs), resulting in serious environmental problems such as high energy consumption, low efficiency, and refrigerant emissions leading to ozone layer depletion and the greenhouse effect. Magnetic refrigeration technology based on the magnetocaloric effect of magnetic materials is considered one of the most promising next-generation solid-state refrigeration solutions due to its outstanding advantages, including high theoretical efficiency (approaching the Carnot cycle), environmental friendliness (no need for harmful gaseous refrigerants), low operating noise, and ease of miniaturization.

[0003] Having NaZn 13 La-Fe-Si based alloys with a crystal structure of α-type are considered one of the most promising room-temperature magnetic refrigerants due to their giant magnetocaloric effect near the Curie temperature, high relative cooling capacity, and the ability to continuously control the Curie temperature in the near-room-temperature region through compositional design (such as replacing Fe with Co and La with Ce). However, the advancement of this system to practical applications still faces a series of interconnected material science and process bottlenecks: (1) Slow phase formation kinetics: obtaining high-purity, high-content NaZn 13 Type 1:13 magnetocaloric phase usually requires heat treatment at 1000℃ for several days or even weeks, resulting in high energy consumption and low efficiency; (2) Intrinsic brittleness and poor machinability: As a typical intermetallic compound, this material has high hardness and poor plasticity, making it difficult to process into complex shapes by conventional means, and it is prone to cracking under the stress of magnetocaloric cycle; (3) First-order phase transition accompanied by significant magnetic / thermal hysteresis: Its giant magnetocaloric effect originates from the first-order itinerant-electron metamagnetic transition, which is accompanied by strong magnetic volume effect, resulting in non-negligible thermal and magnetic hysteresis, which reduces the energy efficiency of the refrigeration cycle.

[0004] Current reports on effectively improving the plastic deformation properties of La-Fe-Si based magnetic refrigeration alloys involve doping with Cu during argon arc melting to generate a non-magnetic refrigeration LaCu2 phase and a high-fault energy HCP structure La1Cu1Si1 phase in the alloy. However, (LaFe... 10.8 CoSi 1.2 ) 55 Cu 45The alloy requires annealing at 1323 K for 7 days to obtain a high content of magnetocaloric phase (less than 60 vol%). Its maximum magnetic entropy change (−ΔS) M ) max At Δμ0H=2 T, it is less than 1.3 J·kg −1 ·K −1 The maximum compressive strain is less than 6%. More importantly, the Cu-induced La1Cu1Si1 phase not only inhibits the formation of the 1:13 magnetocaloric phase (this phase, unlike the tetragonal La1Fe1Si1 phase, is difficult to transform into a magnetocaloric phase through a phase transformation reaction), but also dominates the macroscopic plastic deformation of the alloy. This leads to an irreconcilable contradiction between plasticity and magnetocaloric properties, preventing synergistic optimization between the two. These defects severely restrict the reliable preparation, processing, and long-term service stability of La-Fe-Si based bulk materials. Summary of the Invention

[0005] This invention addresses the inherent brittleness of La-Fe-Si based magnetic refrigeration materials, the poor mechanical properties of their composite materials, and the technical problems of long production cycles and complex processes in traditional preparation methods. It proposes a method to regulate and improve the comprehensive performance of La-Fe-Si based magnetic refrigeration bulk materials by using micron-sized Fe-Ni based multi-principal-element alloys as binders and combining them with high-temperature discharge plasma sintering (SPS) rapid prototyping technology.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for preparing a La-Fe-Si based composite material with good plastic deformation properties is characterized by uniformly mixing La-Fe-Si based magnetic refrigeration material powder (main phase particles) and micron-sized Fe-Ni alloy material powder (binder), forming the mixture by high-temperature discharge plasma sintering, and then annealing it in a protective atmosphere to obtain a magnetic refrigeration bulk material; wherein the La-Fe-Si based magnetic refrigeration material is La 1.0 Ce x (Fe 1-y Co y ) 13-z Si z Compounds, wherein 0.1≤x≤0.3, 0.01≤y≤0.08, 1.0≤z≤1.6, and whose particle size is ≤90μm.

[0008] Preferably, the micron-sized Fe-Ni alloy material is FeCr. m Co n Ni, where 0≤m≤1.0, 0≤n≤1.0.

[0009] Preferably, the La 1.0 Ce x (Fe1-y Co y ) 13-z Si z The compound is (La 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 .

[0010] Preferably, the (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The compound is NaZn with a content ≤100 wt%. 13 1:13 phase (La) with a morphological structure 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Rapidly quenched thin strip.

[0011] Preferably, the La-Fe-Si based magnetic refrigeration material has a NaZn content of ≥70 wt%. 13 A 1:13 phase structure with α-Fe phase content ≤30 wt% and the remainder being a rare earth-rich 1:1:1 phase of La. 1.0 Ce x (Fe 1-y Co y ) 13-z Si z Melt-quenched thin strip.

[0012] Preferably, the particle size of the La-Fe-Si based magnetic refrigeration material powder is ≤90 μm, and the particle size of the micron-sized Fe-Ni alloy material powder is ≤25 μm; the amount of micron-sized Fe-Ni alloy material powder added is 1-10 wt%.

[0013] Preferably, the sintering temperature is 750-950 ℃, the pressure is 10-100 MPa, and the holding time is 1-10 min.

[0014] Preferably, the sintering heating rate is 100±50 K / min, and the pressure is 30-50 MPa; the sintering process is carried out under a vacuum degree <10. -4 The experiment was conducted under Pa conditions.

[0015] Preferably, after sintering, the material is annealed in a protective gas atmosphere at a temperature of 950-1150 °C for 24±12 h.

[0016] The step of the discharge plasma sintering is as follows: (La)1-x Ce x (Fe) y Co 1-y ) 13-z Si z The Fe-Ni alloy binder is mixed evenly in proportion and loaded into a mold; the mold is placed in a sintering furnace and a pressure of 30-50 MPa is applied; it is heated to 750-950℃ at a rate of 100±50K / min and held at the temperature and pressure for 5-10 minutes; then it is cooled with the furnace to below 200℃ to release the pressure and demold to obtain the La-Fe-Si based composite magnetic refrigeration block.

[0017] This invention is achieved using the following technical solution: First, NaZn that has undergone pre-annealing treatment to obtain a purity of over 70 wt% is... 13 Type 1:13 magnetocaloric phase (La) 1-x Ce x (Fe) y Co 1-y ) 13-z Si z The bulk material is mechanically crushed and ground to select alloy powder with a particle size ≤90 μm as the matrix. Subsequently, the powder is uniformly mixed with micron-sized Fe-Ni alloy binder powder. The mixed powder is rapidly densified under vacuum conditions by spark plasma sintering (SPS) at a temperature of 750-950 ℃, a pressure of 30-50 MPa, and a holding time of 5-10 min. The sintered bulk material can be vacuum annealed at 950-1150 ℃ according to performance requirements to finally obtain a high-performance La-Fe-Si based composite magnetic refrigeration material.

[0018] During SPS sintering, the Fe-Ni based binder, under the instantaneous high-temperature field provided by SPS, fills the pores through reliable metallurgical bonding with the matrix particles and induces a controllable "thermal decomposition" effect at the interface. This causes some of the 1:13 phase to transform into the tough α-Fe phase and the stable (La,Ce)1(Fe,Co)1Si1 (1:1:1) phase, ultimately forming a dense multiphase composite structure in a very short time, resulting in a significant improvement in the material's mechanical properties. Furthermore, vacuum annealing after sintering can further adjust the morphology, distribution, and proportion of the α-Fe phase, the 1:1:1 phase, and the residual 1:13 phase, significantly enhancing the material's strength, plasticity, and structural stability while maintaining a high magnetic entropy change.

[0019] Ni is the core component of the multi-principal alloy binder. Its synergistic configuration with elements such as Fe, Cr, and Co endows the binder with intrinsic high ductility, promoting the overall plasticity of the composite material. In addition, Ni has moderate chemical affinity and interdiffusion ability with the matrix elements. Under the action of the instantaneous high temperature field of SPS, it can induce a controllable partial decomposition of the 1:13 phase in the interface region, generating a dispersed α-Fe toughening phase and a 1:1:1 phase, constructing a multiphase composite structure in which the toughening phase, stable phase, and magnetocaloric phase coexist synergistically. The alloy maintains a three-phase coexistence of "1:13 phase + α-Fe phase + 1:1:1 phase". Through subsequent vacuum annealing, the morphology, spatial distribution and volume fraction of the above three phases can be further finely controlled (α-Fe phase + 1:1:1 phase → 1:13 phase). Finally, while maintaining a high magnetic entropy change, the alloy system has achieved a breakthrough from intrinsic brittle fracture to significant macroscopic plastic deformation. That is, the compressive plastic strain has increased from almost zero in traditional materials to more than 40%, marking the first time that La-Fe-Si based magnetic refrigeration materials have combined excellent functional properties and machinability.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1) This invention directly uses (La, Ce)-Fe-Co-Si material with a high purity 1:13 phase (>70wt%) obtained through annealing as the sintering matrix. This matrix has a clear and singular magnetocaloric phase target, avoiding the uncertainty of long-term in-situ phase formation in traditional methods. Utilizing the characteristics of SPS rapid sintering, the existing 1:13 phase can be controllably partially decomposed, and the degree of decomposition can be precisely controlled by adjusting process parameters, thereby achieving an optimized configuration of the α-Fe phase, 1:1:1 phase, and 1:13 phase ratio in the final material, introducing a tough phase while ensuring magnetocaloric performance.

[0022] 2) This invention uses a Fe-Ni based multi-principal alloy as a binder, whose excellent ductility significantly improves the overall plasticity of the composite material. Under the combined action of localized high temperature and electric field in SPS, the binder can form a strong metallurgical bond with the 1:13 main phase particles, effectively filling pores and increasing density. Simultaneously, the moderate interdiffusion between the binder and the main phase avoids the formation of harmful brittle phases, ensuring the stability of the material's magnetocaloric properties.

[0023] 3) By controlling the amount of binder added, the SPS sintering temperature, and the subsequent annealing process, directional design of material properties can be achieved within the same technical framework: direct sintering without adding binder yields materials characterized by high strength and high magnetic entropy change; after sintering with 10wt% binder, the material exhibits excellent plastic deformation capacity and processability; subsequent annealing of the sintered sample achieves a synergistic improvement and optimal balance of strength, plasticity, and magnetocaloric properties. This flexible combination of processes significantly shortens the preparation cycle.

[0024] 4) The process mechanism of this invention is clear, with high repeatability and controllability. Its core lies in utilizing the "localized high temperature and binder synergy" effect of SPS to controllably reconstruct the structure of a pre-prepared high-purity 1:13 phase. By precisely controlling the sintering and annealing parameters, reliable regulation of the final phase composition and properties can be achieved, significantly improving the mechanical reliability of the material while maintaining high magnetic cooling capacity.

[0025] In summary, this invention effectively solves the problems of poor processability and difficulty in achieving synergistic magnetothermal and mechanical properties in La-Fe-Si materials. At the same time, it significantly improves process integration, providing a feasible technical path for the engineering application of the material. Attached Figure Description

[0026] Figure 1 The results from Examples 1-4 are as follows: no adhesive added, 10 wt% FeNi binary alloy adhesive added, 10 wt% FeCoNi ternary medium-entropy alloy adhesive added, and 10 wt% FeCrCoNi quaternary high-entropy alloy adhesive added. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 XRD pattern of magnetic refrigeration composite material after SPS sintering.

[0027] Figure 2 (La) without adhesive as in Example 1 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Backscattered image of magnetic cooling block after SPS sintering.

[0028] Figure 3 The (La) without adhesive as described in Example 1 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The magnetic entropy change-temperature relationship curve of the magnetic refrigeration block after SPS sintering.

[0029] Figure 4a , Figure 4b and Figure 4c The (La) prepared in Examples 2 (FeNi), 3 (FeCoNi), and 4 (FeCrCoNi) are respectively. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Backscattered image of a magnetic refrigeration composite material with 10wt% binder.

[0030] Figure 5 The (La) sintered by SPS in Examples 2-5 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 / 10wt%FeNi, (La 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 / 10wt%FeCoNi, (La 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 / 10wt%FeCrCoNi magnetic refrigeration composite material and (La 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Magnetic entropy change-temperature relationship curve of 10wt%FeNi bulk material after annealing at 1050 ℃ for 1 day.

[0031] Figure 6a The (La) prepared by SPS sintering in Example 5 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 XRD pattern of 10wt%FeNi magnetic refrigeration composite block after annealing at 1050 ℃ for 1 day.

[0032] Figure 6b The (La) prepared by SPS sintering in Example 5 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Backscattered image of a 10wt% FeNi magnetic refrigeration composite block after annealing at 1050 ℃ for 1 day.

[0033] Figure 7 (La) prepared by different processes in Examples 1-5 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Compressive stress-strain curves of the basic magnetic refrigeration composite material: Example 1 is a binder-free SPS sintered sample; Examples 2-4 are SPS sintered samples with 10 wt% FeNi binary alloy, FeCoNi ternary medium-entropy alloy, and FeCrCoNi quaternary high-entropy alloy binders, respectively; Example 5 is an SPS sintered sample with 10 wt% FeNi binary alloy binder annealed at 1050℃ for 1 day. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the embodiments.

[0035] Example 1

[0036] A La-Fe-Si based magnetic refrigeration bulk material, the preparation method of which is as follows:

[0037] Step 1: Press (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The alloy's nominal composition consists of raw materials of pure La (≥99.5 wt%), Ce (≥99.5 wt%), Fe (≥99.95 wt%), Co (≥99.5 wt%), and Si (≥99.95 wt%) in bulk form, with the balance of La and Ce at 5 wt% to compensate for mass loss due to volatilization during the smelting process. The alloy is obtained through melt rapid quenching. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy castings;

[0038] Step 2: Take the untreated (La) obtained in Step 1 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The alloy castings were annealed at 1050 °C for 8 hours under a 300 mbar argon atmosphere, followed by cooling in ice water.

[0039] Step 3: Anneal the (La) obtained in Step 2 1.0 Ce 0.3 )Fe 11.0 Co 0.8Si 1.2 Alloy castings were mechanically ground and sieved to obtain powder with a particle size ≤90 μm (La). 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy powder particles;

[0040] Step 4: Weigh 8g of powder with a particle size ≤90 μm (La 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 alloy powder;

[0041] Step 5: Load the powder particles into a Φ15mm×12mm mold and pre-compact them.

[0042] Step 6: Using the sintering furnace program control, apply a pressure of 50 MPa and heat the mold to 850 ℃ at a heating rate of 100 K / min. After the temperature stabilizes, hold the mold at that temperature for 5 minutes and then stop heating. Allow the mold to cool to room temperature and release the pressure. Then, remove the mold for demolding.

[0043] The Φ15mm×5mm (La) obtained through the above six steps 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Magnetic refrigeration blocks.

[0044] In Example 1, the (La) sintered by SPS 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 See the XRD pattern of the magnetic refrigeration bulk material. Figure 1 .

[0045] In Example 1, SPS sintered (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 See backscattered images of the magnetically cooled bulk material. Figure 2 The sample retained a large amount of 1:13 phase as well as a small amount of α-Fe phase and La-rich phase.

[0046] In Example 1, SPS sintered (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2The relationship between the magnetic entropy change of the magnetic refrigeration bulk material and temperature can be found in the curve. Figure 3 The maximum magnetic entropy of the sample under a 2T magnetic field change is ~8.53 J·kg. -1 ·K -1 .

[0047] In Example 1, SPS sintered (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 See the compressive stress-strain curve of the magnetic refrigeration bulk material. Figure 7 The sample exhibits good mechanical properties (maximum compressive strength) (~861 MPa).

[0048] Example 2

[0049] Step 1: Press (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The alloy's nominal composition consists of raw materials of pure La (≥99.5 wt%), Ce (≥99.5 wt%), Fe (≥99.95 wt%), Co (≥99.5 wt%), and Si (≥99.95 wt%) in bulk form, with the balance of La and Ce at 5 wt.% to compensate for mass loss due to volatilization during the smelting process. The alloy is obtained through melt rapid quenching. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy castings;

[0050] Step 2: Take the untreated (La) obtained in Step 1 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The alloy castings were annealed at 1050 °C for 8 hours under a 300 mbar argon atmosphere, followed by cooling in ice water.

[0051] Step 3: Anneal the (La) obtained in Step 2 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy castings were mechanically ground and sieved to obtain powder with a particle size ≤90 μm (La). 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy powder particles;

[0052] Step 4: Weigh 0.8 g of FeNi powder with a particle size of 5 μm;

[0053] Step 5: Weigh 7.2 g of powder with a particle size ≤90 μm (La 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 alloy powder;

[0054] Step 6: Mix the powder for 30 minutes, then put the powder particles into a Φ15mm×12mm mold and pre-compact them.

[0055] Step 7: Using the sintering furnace program control, apply a pressure of 50 MPa and heat the mold to 850 ℃ at a heating rate of 100 K / min. After the temperature stabilizes, hold the mold at that temperature for 5 minutes and then stop heating. Allow the mold to cool to room temperature and release the pressure. Then, remove the mold for demolding.

[0056] The Φ15mm×5mm (La) obtained through the above seven steps 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 / 10wt% FeNi magnetic refrigeration composite block.

[0057] In Example 2, SPS sintered (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 XRD pattern of / 10wt% FeNi magnetic refrigeration bulk material is shown below. Figure 1 .

[0058] In Example 2, (La) was prepared by SPS sintering. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 See the backscattering image of the / 10wt%FeNi magnetic refrigeration bulk material. Figure 4a In the sample, the 1:13 phase thermally decomposes into the α-Fe phase and the La-rich phase.

[0059] In Example 2, (La) was prepared by SPS sintering. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The relationship between the magnetic entropy change and temperature of the / 10wt%FeNi magnetic refrigeration bulk material is shown in the curve. Figure 5 .

[0060] In Example 2, (La) was prepared by SPS sintering. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The compressive stress-strain curve of the / 10wt%FeNi magnetic refrigeration bulk material is shown below. Figure 7 The sample exhibits excellent mechanical properties, with obvious plastic deformation characteristics, strain exceeding 59%, yield strength ~504 MPa, and maximum compressive strength exceeding 1639 MPa.

[0061] Example 3

[0062] A La-Fe-Si based magnetic refrigeration bulk material, the preparation method of which is as follows:

[0063] Step 1: Press (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The alloy's nominal composition consists of raw materials of pure La (≥99.5 wt%), Ce (≥99.5 wt%), Fe (≥99.95 wt%), Co (≥99.5 wt%), and Si (≥99.95 wt%) in bulk form, with the balance of La and Ce at 5 wt% to compensate for mass loss due to volatilization during the smelting process. The alloy is obtained through melt rapid quenching. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy castings;

[0064] Step 2: Take the untreated (La) obtained in Step 1 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The alloy castings were annealed at 1050 °C for 8 hours under a 300 mbar argon atmosphere, followed by cooling in ice water.

[0065] Step 3: Anneal the (La) obtained in Step 2 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy castings were mechanically ground and sieved to obtain powder with a particle size ≤90 μm (La). 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si1.2 Alloy powder particles;

[0066] Step 4: Weigh 0.8 g of FeCoNi powder with a particle size of 5 μm;

[0067] Step 5: Weigh 7.2 g of powder with a particle size ≤90 μm (La 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 alloy powder;

[0068] Step 6: Mix the powder for 30 minutes, then put the powder particles into a Φ15mm×12mm mold and pre-compact them.

[0069] Step 7: Using the sintering furnace program control, apply a pressure of 50 MPa and heat the mold to 850 ℃ at a heating rate of 100 K / min. After the temperature stabilizes, hold the mold at that temperature for 5 minutes and then stop heating. Allow the mold to cool to room temperature and release the pressure. Then, remove the mold for demolding.

[0070] The Φ15mm×5mm (La) obtained through the above seven steps 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 / 10wt%FeCoNi magnetic refrigeration composite block.

[0071] In Example 3, (La) was prepared by SPS sintering. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 See the XRD pattern of the / 10wt%FeCoNi magnetic refrigeration bulk material. Figure 1 .

[0072] The (La) prepared by SPS sintering in Example 3 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 See the backscattering image of the / 10wt%FeCoNi magnetic refrigeration bulk material. Figure 4b In the sample, the 1:13 phase thermally decomposes into the α-Fe phase and the La-rich phase.

[0073] The (La) prepared by SPS sintering in Example 3 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2The relationship between the magnetic entropy change and temperature of the / 10wt%FeCoNi magnetic refrigeration bulk material is shown in the curve. Figure 5 .

[0074] The (La) prepared by SPS sintering in Example 3 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The compressive stress-strain curve of the / 10wt%FeCoNi magnetic refrigeration bulk material is shown below. Figure 7 The strain of the sample exceeded 21%, which was lower than that of the sample in Example 2; however, the sample in Example 3 exhibited a larger modulus and yield strength (~579 MPa) during the elastic deformation stage.

[0075] Example 4

[0076] A La-Fe-Si based magnetic refrigeration bulk material, the preparation method of which is as follows:

[0077] Step 1: Press (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The alloy's nominal composition consists of raw materials of pure La (≥99.5 wt%), Ce (≥99.5 wt%), Fe (≥99.95 wt%), Co (≥99.5 wt%), and Si (≥99.95 wt%) in bulk form, with the balance of La and Ce at 5 wt% to compensate for mass loss due to volatilization during the smelting process. The alloy is obtained through melt rapid quenching. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy castings;

[0078] Step 2: Take the untreated (La) obtained in Step 1 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The alloy castings were annealed at 1050 °C for 8 hours under a 300 mbar argon atmosphere, followed by cooling in ice water.

[0079] Step 3: Anneal the (La) obtained in Step 2 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy castings were mechanically ground and sieved to obtain powder with a particle size ≤90 μm (La). 1.0 Ce 0.3)Fe 11.0 Co 0.8 Si 1.2 Alloy powder particles;

[0080] Step 4: Weigh 0.8 g of FeCrCoNi powder with a particle size of 5 μm;

[0081] Step 5: Weigh 7.2 g of powder with a particle size ≤90 μm (La 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 alloy powder;

[0082] Step 6: Mix the powder for 30 minutes, then put the powder particles into a Φ15mm×12mm mold and pre-compact them.

[0083] Step 7: Using the sintering furnace program control, apply a pressure of 50 MPa and heat the mold to 850 ℃ at a heating rate of 100 K / min. After the temperature stabilizes, hold the mold at that temperature for 5 minutes and then stop heating. Allow the mold to cool to room temperature and release the pressure. Then, remove the mold for demolding.

[0084] The Φ15mm×5mm (La) obtained through the above seven steps 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 / 10wt%FeCrCoNi magnetic refrigeration composite block.

[0085] The (La) prepared by SPS sintering in Example 4 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 See the XRD pattern of the / 10wt%FeCrCoNi magnetic refrigeration bulk material. Figure 1 .

[0086] The (La) prepared by SPS sintering in Example 4 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 See the backscatter image of the / 10wt%FeCrCoNi magnetic refrigeration bulk material. Figure 4c In the sample, the 1:13 phase thermally decomposes into the α-Fe phase and the La-rich phase.

[0087] The (La) prepared by SPS sintering in Example 4 1.0 Ce 0.3 )Fe11.0 Co 0.8 Si 1.2 The relationship between the magnetic entropy change and temperature of the / 10wt%FeCrCoNi magnetic refrigeration bulk material is shown in the curve. Figure 5 .

[0088] The (La) prepared by SPS sintering in Example 4 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The compressive stress-strain curve of the / 10wt% FeCrCoNi magnetic refrigeration bulk material is shown below. Figure 7 The strain of the sample exceeded 47%, which is between that of the samples in Example 2 and Example 3, and the yield strength was ~556 MPa.

[0089] Example 5

[0090] Step 1: Press (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The alloy's nominal composition consists of raw materials of pure La (≥99.5 wt%), Ce (≥99.5 wt%), Fe (≥99.95 wt%), Co (≥99.5 wt%), and Si (≥99.95 wt%) in bulk form, with the balance of La and Ce at 5 wt% to compensate for mass loss due to volatilization during the smelting process. The alloy is obtained through melt rapid quenching. 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy castings;

[0091] Step 2: Take the untreated (La) obtained in Step 1 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The alloy castings were annealed at 1050 °C for 8 hours under a 300 mbar argon atmosphere, followed by cooling in ice water.

[0092] Step 3: Anneal the (La) obtained in Step 2 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Alloy castings were mechanically ground and sieved to obtain powder with a particle size ≤90 μm (La). 1.0 Ce 0.3 )Fe 11.0 Co0.8 Si 1.2 Alloy powder particles;

[0093] Step 4: Weigh 0.8 g of FeNi powder with a particle size of 5 μm;

[0094] Step 5: Weigh 7.2 g of powder with a particle size ≤90 μm (La 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 alloy powder;

[0095] Step 6: Mix the powder for 30 minutes, then put the powder particles into a Φ15mm×12mm mold and pre-compact them.

[0096] Step 7: Using the sintering furnace program control, apply a pressure of 50 MPa and heat the mold to 850 ℃ at a heating rate of 100 K / min. After the temperature stabilizes, hold the mold at that temperature for 5 minutes and then stop heating. Allow the mold to cool to room temperature and release the pressure. Then, remove the mold for demolding.

[0097] Step 8: Anneal the demolded sample obtained in Step 7 at 1050 °C for 1 day under a 300 mbar argon atmosphere, and then cool it in ice water.

[0098] The Φ15mm×5mm (La) obtained through the above eight steps 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 / 10wt% FeNi magnetic refrigeration composite block.

[0099] The (La) prepared in Example 5 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 See the XRD pattern of the / 10wt%FeNi magnetic refrigeration bulk material. Figure 6a .

[0100] The (La) prepared in Example 5 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 See backscatter image of / 10wt% FeNi magnetic refrigeration bulk material. Figure 6b A large amount of 1:13 phase reappeared in the sample, in addition to residual α-Fe phase and La-rich phase.

[0101] The (La) prepared in Example 51.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The relationship between the magnetic entropy change and temperature of the / 10wt% FeNi magnetic refrigeration bulk material is shown in the curve. Figure 5 Compared to the unannealed samples 2, 3 and 4, the magnetocaloric properties of sample 5 showed a significant improvement.

[0102] The (La) prepared in Example 5 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The compressive stress-strain curve of the / 10wt%FeNi magnetic refrigeration bulk material is shown below. Figure 7 The sample maintained plastic deformation characteristics, with a yield strength of ~402 MPa and a maximum compressive strength exceeding 477 MPa.

Claims

1. A method for preparing a La-Fe-Si based composite material with good plastic deformation properties, characterized in that, La-Fe-Si based magnetic refrigeration material powder and micron-sized Fe-Ni alloy material powder were uniformly mixed and then sintered using high-temperature discharge plasma sintering to prepare a bulk magnetic refrigeration material; the La-Fe-Si based magnetic refrigeration material is La 1.0 Ce x (Fe 1-y Co y ) 13- z Si z Compounds, wherein 0.1≤x≤0.3, 0.01≤y≤0.08, 1.0≤z≤1.6, have a particle size ≤90μm.

2. The preparation method according to claim 1, characterized in that, The micron-scale Fe-Ni gold material is FeCr m Co n Ni, where 0 ≤ m ≤ 1.0, 0 ≤ n ≤ 1.

0.

3. The preparation method according to claim 1, characterized in that, The La 1.0 Ce x (Fe 1-y Co y ) 13-z Si z The compound is (La 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 .

4. The preparation method according to claim 3, characterized in that, The (La) 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 The compound is NaZn with a content ≤100 wt%. 13 1:13 phase (La) with a morphological structure 1.0 Ce 0.3 )Fe 11.0 Co 0.8 Si 1.2 Rapidly quenched strip.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The La-Fe-Si based magnetic refrigeration material contains ≥70 wt% NaZn 13 A 1:13 phase structure with α-Fe phase content ≤30 wt% and the remainder being a rare earth-rich 1:1:1 phase of La. 1.0 Ce x (Fe 1-y Co y ) 13-z Si z Melt-quenched thin strip.

6. The preparation method according to any one of claims 1 to 4, characterized in that, The particle size of the La-Fe-Si based magnetic refrigeration material powder is ≤90 μm, and the particle size of the micron-sized Fe-Ni alloy material powder is ≤25 μm; the amount of micron-sized Fe-Ni alloy material powder added is 1-10 wt%.

7. The preparation method according to any one of claims 1 to 4, characterized in that, The sintering temperature is 750-950 ℃, the pressure is 10-100 MPa, and the holding time is 1-10 min.

8. The preparation method according to claim 7, characterized in that, The sintering heating rate was 100±50 K / min, and the pressure was 30-50 MPa; the sintering process was carried out under a vacuum of <10 kJ / min. -4 The experiment was conducted under Pa conditions.

9. The preparation method according to claim 7, characterized in that, After sintering, the material is annealed in a protective gas atmosphere at a temperature of 950-1150 ℃.

10. The La-Fe-Si based composite material with good plastic deformation properties obtained by the method according to any one of claims 1 to 9.

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