534 results about "Coercivity" patented technology

The invention discloses a neodymium-iron-boron magnet with double main phases and light rare earth diffusion based on asymmetric cerium distribution and a preparation method, and relates to the technical field of neodymium-iron-boron magnets. The method comprises the steps that a diffusion matrix is prepared through a double-main-phase technology, in the double-main-phase technology, the components of a main-phase alloy and an auxiliary-phase alloy are RaCebFe100-a-b-c-dMcBd, R is PrNd alloy or Nd metal, M is at least one of Cu, Al, Zr, Co and Ga, the content of Ce in the main-phase alloy is larger than that of Ce in the auxiliary-phase alloy, then the upper surface and the lower surface of the diffusion matrix are coated with a diffusion source solution, and the diffusion matrix is obtained through heat treatment. Carrying out heat treatment and aging treatment to obtain a neodymium-iron-boron magnet; the diffusion source solution is formed by mixing a diffusion source and a solvent, and the diffusion source is (PrmNdn) aAlbCucZrdCoeMgf. The neodymium-iron-boron magnet obtained through the method has high residual magnetism and high coercive force at the same time, the diffusion efficiency of the diffusion source is high, and the rare earth utilization rate is increased.

The invention discloses an yttrium-rich neodymium-iron-boron magnet and a preparation method thereof, and belongs to the technical field of rare earth permanent magnet material preparation. The preparation method comprises the following steps: mixing yttrium-rich neodymium-iron-boron matrix alloy powder with grain boundary doped alloy powder containing Gd and / or Ho, and carrying out compression molding and sintering tempering treatment to obtain a first yttrium-rich neodymium-iron-boron magnet. According to the invention, the grain boundary doped alloy powder containing Gd and / or Ho is added into the yttrium-rich neodymium iron boron matrix alloy powder and then is sintered, so that a continuous and uniform non-magnetic thin-wall grain boundary phase structure is formed in the grain boundary, and the coercive force of the magnet is enhanced. Dy and / or Tb heavy rare earth element grain boundary diffusion is carried out based on the first yttrium-rich neodymium-iron-boron magnet after grain boundary modification, a second yttrium-rich neodymium-iron-boron magnet is obtained, the diffusion depth of Dy and / or Tb in the magnet can be increased, the utilization rate can be increased, the cost can be reduced, the coercivity of the magnet can be improved, and the adverse effect of Dy and / or Tb on residual magnetism can be reduced.

The invention belongs to the technical field of iron-based material preparation, and particularly relates to a method for optimizing soft magnetic performance of an iron-based amorphous alloy through cyclic stress annealing, the iron-based amorphous alloy and application. The method comprises the steps that periodic stress is applied to the iron-based amorphous alloy, and periodic strain is generated; the peak strain of the periodic strain is less than or equal to 2%, and the valley strain of the periodic strain is lower than the peak strain. Appropriate periodic stress is applied to the iron-based amorphous alloy at the low temperature, periodic strain is generated, the negative influence of rapid cooling on the soft magnetic performance during preparation of the iron-based amorphous alloy in the prior art can be improved, the brittleness problem generated by high-temperature annealing can be avoided, the soft magnetic performance and brittleness are better balanced, and the service life of the iron-based amorphous alloy is prolonged. And the effect of coexistence of ultralow coercive force and good toughness is achieved.

The invention relates to a Fe-Si-Nb-B-Cu-Er amorphous alloy and a preparation method and application thereof, and belongs to the technical field of metal materials. The atomic percent expression of the Fe-Si-Nb-B-Cu-Er amorphous alloy disclosed by the invention is (Fe < 83 > Si < 3 > Nb < 4 > B < 9 > Cu < 1 >) < 100-x > Er < x >, wherein x is equal to 3.5 to 4.5. The rare earth element Er is added to optimize the soft magnetic performance of a Fe-Si-Nb-B-Cu amorphous alloy system, the coercive force of the Fe-Si-Nb-B-Cu amorphous alloy system is reduced, the preparation method is simple and easy to implement, and the Fe-based amorphous alloy with the excellent soft magnetization performance is obtained. The magnetization intensity of the amorphous alloy is sharply increased along with increase of a magnetic field under a low magnetic field and then gradually reaches saturation, typical soft magnetic performance is presented, and the amorphous alloy has wide application space in the field of magnetic materials.

The invention belongs to the technical field of particle accelerators, and discloses a nonlinear impact magnet based on a nanocrystalline magnetic material and a matched power supply system. The nonlinear impact magnet comprises a magnetic core and a magnet exciting coil assembly, the magnetic core comprises magnetic poles and a magnetic yoke; the magnetic pole and the magnet yoke are both of a fully-symmetrical annular structure, and the magnet yoke is arranged on the periphery of the magnetic pole. The magnetic pole comprises N same magnetic pole units, N is 4, 6 or 8, and the magnetic pole is made by laminating nanocrystalline strips; and the excitation coil assembly is wound outside each magnetic pole unit. Compared with a traditional silicon steel sheet or ferrite magnetic core, the magnet provided by the invention can improve the uniformity of a magnetic field, and the magnetic pole made of the nanocrystalline strip with ultrahigh magnetic conductivity and low coercive force has stronger magnetic field uniformity and low disturbance characteristic; and the design requirement of the STCF clash ring off-axis injection system for low disturbance of the circulating beam bunch can be better met.

The present invention provides a flywheel energy storage flux adjustable induction motor and its magnetic adjustment method, wherein the motor comprises two permanent magnets with different coercive forces and a DC magnetic adjustment winding. A square wave pulse is input into the DC magnetic adjustment winding to generate a magnetic adjustment magnetic field, so that the residual magnetism of the low-coercive force permanent magnet changes in magnitude or direction, thereby realizing rapid adjustment of the motor air gap flux. When the motor is working, the DC magnetic adjustment winding is disconnected, and the residual magnetic flux generated by the high-coercive force permanent magnet and the low-coercive force permanent magnet enters the air gap in parallel to provide excitation flux for the motor; when the motor is on standby, a negative square wave pulse is input into the DC magnetic adjustment winding to generate a magnetic adjustment magnetic field that can reversely saturate magnetize the low-coercive force permanent magnet, so that the low-coercive force permanent magnet is reversely magnetized, and the residual magnetic flux of the high-coercive force and low-coercive force permanent magnets is equal in magnitude and opposite in direction, so that the air gap flux is reduced to 0, thereby eliminating standby iron loss. In addition, the DC magnetic adjustment winding can also be used as a backup excitation source to prevent the risk of permanent magnet demagnetization.

The invention provides a magnetic code disc film material and a preparation method and application thereof. By introducing the TiN layer, a proper amount of nitrogen atoms can enter lattice gaps of iron, electron cloud distribution of iron atoms is changed, and the magnetic moment of the iron atoms is changed; the magnetic moment of Fe atoms can be influenced by N atoms and crystal structures, an alpha-Fe8N phase is formed in FeCoCr through introduction of N ions, the average magnetic moment of each Fe atom in the alpha-Fe8N phase is 2.4 mu B, alpha-Fe8N is a metastable phase, a sample can finally form stable gamma '-Fe4N through annealing, and the magnetic moment of the stable gamma'-Fe4N is generally about 2.5 mu B-2. 7 mu B and is higher than the magnetic moment 2.2 mu B of the Fe atoms in metal Fe; besides, Ti forms a Ti-Fe weak magnetic phase pinning magnetic domain wall in the FeCoCr thin film, and the coercive force and residual magnetism of the FeCoCr layer can be effectively improved at the same time through the method.

A treatment method for enhancing coercive force of neodymium iron boron magnet includes the following steps: subjecting the neodymium iron boron magnet to electrochemical deposition in a diffusion water-based solution to obtain a neodymium iron boron magnet containing a heavy rare earth; and subjecting the neodymium iron boron magnet containing the heavy rare earth to heat treatment to complete enhancement of the coercive force of the neodymium iron boron magnet. The raw material used in the present invention is cheap heavy rare earth compounds which increases the selection of diffusion sources and lowers costs. Metal alloy particles are mainly obtained in a nanoscale size and can effectively enter crystal grains, and low-melting-point metal alloy components can enhance a demagnetizing coupling effect between main phase grains. According to the present invention, the coercive force of the magnet is increased by nearly 30%, and residual magnetism is almost not changed.

The invention discloses a method for improving performance of rare earth permanent magnet sintered neodymium iron boron grain boundary diffusion, and belongs to the technical field of rare earth permanent magnet materials. The method comprises the steps that a low-melting-point metal layer and a diffusion layer containing heavy rare earth elements are sequentially formed on the surface of a clean sintered neodymium-iron-boron magnet, and then vacuum diffusion heat treatment and tempering treatment are conducted. Wherein the low-melting-point metal layer comprises at least one of copper, aluminum, gallium and tin or an alloy of the copper, the aluminum, the gallium and the tin; the heavy rare earth element comprises at least one of dysprosium, terbium, holmium and gadolinium. The low-melting-point metal layer is preferentially diffused and wets the grain boundary in the heat treatment process, heavy rare earth elements are promoted to be deeply and uniformly diffused towards the interior of the magnet along the grain boundary, so that a heavy rare earth-rich shell layer is formed outside main phase grains of the magnet, and the intrinsic coercive force is improved; meanwhile, the low-melting-point metal forms a strengthening phase at the grain boundary, the brittleness of the magnet after diffusion is improved, the surface corrosion phenomenon is restrained, and collaborative optimization of the comprehensive performance of the magnet is achieved.

The invention discloses an energy-saving control method for a new-energy high-low-voltage direct-current relay. The energy-saving control method comprises the steps of analyzing a mapping relation between a silicon steel sheet stacking angle and a magnetic flux path deviation, calculating magnetic domain wall moving resistance according to magnetic domain boundary stress, determining a magnetic domain overturning speed by combining a magnetic field change rate, and measuring a hysteresis loop width parameter. Adjusting the width and frequency of the excitation current pulse according to the magnetic domain overturning frequency and the hysteresis loop offset and width to obtain an optimized excitation current pulse sequence, and determining the hysteresis loop expansion speed according to the hysteresis loop area change rate; the local high-temperature area temperature is analyzed through the iron core temperature rise rate, the local high-temperature area distribution and the magnetic domain energy dissipation data, if the local high-temperature area temperature exceeds the preset threshold value, the excitation current pulse is adjusted, stable iron core temperature rise control data is obtained, the coercive force change amplitude is determined, the magnetic hysteresis loss and the temperature rise are reduced, the stability of the relay under high-frequency switching is improved, and the reliability of the relay is improved. And the operation efficiency and reliability of the system are greatly improved.

The invention provides a Y-rich rare earth permanent magnet and a preparation method and a magnetic performance improving method thereof, and the performance improving method comprises the steps: uniformly mixing to-be-diffused metal powder containing Dy and / or Tb elements with an organic solvent to obtain to-be-diffused alloy liquid; the alloy liquid to be diffused is attached to the surface of the Y-rich rare earth permanent magnet, and the Y-rich rare earth permanent magnet is placed in a vacuum sintering furnace; the Y-rich rare earth permanent magnet is subjected to grain boundary diffusion heat treatment through the vacuum sintering furnace, so that Dy and / or Tb elements are diffused into the surface layer of a main phase lattice of the Y-rich rare earth permanent magnet; and carrying out tempering treatment on the Y-rich rare earth permanent magnet. The problems that the coercive force of an existing Y-containing magnet is difficult to effectively improve, and residual magnetism is easily reduced can be effectively solved.

The invention belongs to the field of magnetic materials. The invention provides a preparation method of a rare earth permanent magnet, which comprises the following steps: weighing rare earth magnetic powder, adding a binder solution, uniformly mixing, and drying until a solvent is completely volatilized to obtain bonded magnetic powder; the bonded magnetic powder is placed in a die cavity of a constant-temperature die for heat preservation and preheating; an inner cavity of the constant-temperature mold is vacuumized to form a vacuum environment, and gas adhering to gaps of the magnetic powder is exhausted; applying a magnetic field to the mold, forming an oriented magnetic field in the mold cavity, arranging easy magnetization axes of the magnetic powder along the direction of the oriented magnetic field, and applying pressing force to obtain a mold pressing blank; and heating and curing the molded green body to obtain the rare earth permanent magnet. The rare earth permanent magnet prepared through the preparation method has high compactness, the residual magnetism and the maximum magnetic energy product capacity of the permanent magnet are improved, rare earth magnetic powder is prevented from being oxidized, and the coercive force of the permanent magnet is remarkably improved.

The invention discloses a corrosion-resistant magnetic temperature compensation alloy and a preparation method thereof, and belongs to the field of soft magnetic materials. The alloy is composed of, by atomic percent, 32%-38% of Ni, 0.8%-1% of Co, 1%-2% of Cr, 0.8%-1% of Mn, 0.8%-1.2% of Si, 1%-2% of Al, 0.4%-0.8% of Ti, 0.1%-0.5% of La, 0.1%-0.2% of B and the balance Fe and impurities. Al, Ti, La and B are added in the form of pre-alloyed AlTiLaB alloy powder. The magnetic temperature compensation alloy is prepared through the steps of smelting, refining, adding of AlTiLaB alloy powder, ultrasonic casting and heat treatment. According to the alloy, the corrosion resistance is improved through cooperation of multiple elements, the magnetization intensity is enhanced, the coercive force is reduced, the alloy is suitable for high-power electromagnetic equipment in a complex corrosion environment, and the performance stability and consistency are good.

The invention discloses a solid flexible neodymium-iron-boron magnet diffusion source and a preparation method and application thereof. The preparation method comprises the following steps: mixing an alloy with a mixed adhesive to prepare diffusion source sol; wherein elements in the alloy comprise rare earth elements and non-rare earth elements; the mixed adhesive comprises a collagen agent, a high-temperature diluent, a low-temperature diluent, a flame retardant and an antioxidant; and carrying out heating drying, cooling and compression molding treatment on the diffusion source sol to prepare the solid flexible neodymium-iron-boron magnet diffusion source. According to the solid-state flexible neodymium-iron-boron magnet diffusion source, diffusion heat treatment is conducted on a commercial sintered neodymium-iron-boron magnet through the diffusion source, the coercive force of the magnet is remarkably improved, and the improvement effect is stable; and meanwhile, the diffusion source has the dual characteristics of solid state and flexibility, can be prepared on a large scale and stably stored, and solves the problems that the neodymium-iron-boron magnet diffusion source is difficult to store and transport.

The invention relates to a Ti element doped high-performance high-temperature samarium cobalt permanent magnet material and a preparation method thereof, and belongs to the field of rare earth permanent magnet materials. Elements of Sm, Co, Fe, Cu, Zr and Ti with the purity higher than 99.9% are uniformly mixed and smelted into an original cast ingot, a powder metallurgy preparation technology is adopted, the cast ingot is ground into alloy powder, and the samarium-cobalt permanent magnet material is prepared through orientation compression, isostatic pressing, high-temperature sintering, solid solution and isothermal aging heat treatment processes. According to the invention, by doping the Ti element, the grain size is increased, the grain boundary impurity phase precipitation is inhibited, and the thickness and the content of the flaky phase are properly reduced, so that the number of reverse magnetization nucleation sites is reduced, and the magnetic properties such as the coercive force and the maximum magnetic energy product of the magnet are effectively improved.

The invention provides a grain boundary diffusion neodymium iron boron magnet and a preparation method thereof, and relates to the technical field of magnetic materials. The preparation method comprises the steps of surface pretreatment and purification, precise diffusion source construction through magnetron sputtering and diffusion promotion through vacuum heat treatment. The core function of pretreatment is to remove surface impurities and lay a foundation for subsequent deposition of alloy films; the proportion of Tb, Al and Cu in a diffusion source is accurately regulated and controlled in the magnetron sputtering stage, and the synergistic effect is achieved; and the vacuum heat treatment promotes Tb to diffuse into the neodymium iron boron. According to the method, a technical closed loop with pretreatment as a basis, a diffusion source as a core and heat treatment as power is formed, the microstructure of the neodymium-iron-boron magnet is optimized, a complete and continuous shell structure with the moderate thickness is formed, the diffusion depth of heavy rare earth is greatly increased, and the service life of the neodymium-iron-boron magnet is prolonged. Finally, the coercive force of the neodymium-iron-boron magnet is remarkably improved, and the utilization rate of heavy rare earth elements is effectively improved. The problem of low Tb utilization rate in the prior art is solved, and the bottleneck of coercive force improvement is broken through.

The invention relates to the technical field of rare earth permanent magnet materials, in particular to a grain boundary diffusion magnet based on a hard magnetic 6: 14 phase and a preparation method of the grain boundary diffusion magnet. Preparing a diffusion source, and loading the diffusion source on the surface of the matrix magnet; carrying out heat preservation diffusion under the environment pressure of which the vacuum degree is less than or equal to 10 <-2 > Pa; and carrying out aging treatment to obtain the grain boundary diffusion magnet based on the hard magnetic 6: 14 phase. The grain boundary phase of the prepared grain boundary diffusion magnet based on the hard magnetism 6: 14 phase is mainly the continuous 6: 14 phase, the hard magnetism is presented, the coercive force is improved, meanwhile, the residual magnetism is prevented from being reduced, the problems that the coercive force of an existing neodymium-iron-boron magnet is improved in a limited mode, and the residual magnetism cannot be prevented from being reduced are solved, and the service life of the neodymium-iron-boron magnet is prolonged. The invention provides a low-cost high-comprehensive-magnetic-performance grain boundary diffusion magnet preparation method.

The invention provides a treatment method for synergistically enhancing the comprehensive performance of a neodymium-iron-boron magnet, and belongs to the technical field of magnetic materials. According to the method, a heavy rare earth layer and a corrosion-resistant metal layer such as copper, nickel and cobalt for promoting grain boundary diffusion of heavy rare earth are respectively deposited on the surface of the neodymium-iron-boron magnet by adopting a multi-layer electroplating method, the coercivity of the neodymium-iron-boron magnet is enhanced through grain boundary diffusion, and the corrosion resistance of the magnet is enhanced through a nickel-cobalt coating. The treatment method comprises the following steps: carrying out electrochemical deposition on the neodymium-iron-boron magnet in a heavy rare earth metal plating solution, and then respectively electroplating a copper plating layer and a nickel-cobalt plating layer to obtain a heavy rare earth-containing plating layer with strong corrosion resistance and good plating film binding force; the neodymium-iron-boron magnet containing the heavy rare earth coating is subjected to heat treatment, and the coercive force of the magnet is improved through heavy rare earth grain boundary diffusion. The neodymium iron boron grain boundary diffusion process and the surface corrosion prevention process are subjected to integrated treatment, the technological process of high-performance neodymium iron boron industrial preparation is shortened, and the coercive force and the corrosion resistance of the magnet are comprehensively enhanced.

The invention provides a magnetically soft alloy-based wave-absorbing composite material as well as a preparation method and application thereof, and belongs to the technical field of electromagnetic wave absorbing materials. The wave-absorbing composite material provided by the invention comprises various magnetically soft alloy substrates prepared from elements such as iron, cobalt, nickel and the like and nitrogen-doped carbon coating the surfaces of the magnetically soft alloy substrates. The coercive force of the soft magnetic alloy is relatively low, so that the magnetic domain wall movement and magnetic moment rotation resistance in the material are reduced, the magnetic conductivity is relatively high, and the nitrogen-doped carbon with high dielectricity is combined to construct a magnetic-dielectric structure, so that the impedance matching between the composite material and the space is improved, and the efficient absorption of electromagnetic waves is promoted. The magnetically soft alloy-based wave-absorbing composite material has the characteristics of strong electromagnetic wave absorption performance and wide absorption frequency band, and is simple in preparation technology and easy for large-scale production.

The invention provides amorphous nanocrystalline soft magnetic alloy powder, a preparation method thereof and a magnetic powder core, and relates to the technical field of soft magnetic materials. According to the preparation method of the amorphous nanocrystalline soft magnetic alloy powder, a high-energy electric pulse technology is adopted, an amorphous alloy material is instantly and rapidly heated and exploded, the particle size of the powder is accurately regulated and controlled by accurately regulating and controlling an energy input parameter and a spacing parameter, and the high-sphericity soft magnetic powder with the median particle size being 0.5-5 microns is prepared; the uniformity and dispersity of the powder are remarkably improved, and the problem of low particle size control precision in the prior art is solved. The preparation method is simple in technological process and low in energy consumption, impurities and defects introduced in a traditional multi-step technology are avoided, and the purity and performance of the material are improved. The prepared amorphous nanocrystalline soft magnetic alloy powder has the characteristics of small particle size, high sphericity, high saturation magnetization, low coercive force and high yield, and is particularly suitable for the fields of high-frequency magnetic elements and precision electronic devices.

The invention provides an MIM injection molding process of a samarium-cobalt permanent magnet, which comprises the following steps: preparing low-coercivity MIM samarium-cobalt magnetic powder, performing high-vacuum banburying and granulation, controlling the injection molding process and external magnetic field intensity, and finally performing optimized degreasing, sintering and aging processes to prepare the MIM samarium-cobalt permanent magnet. According to the method, the input amount of Sm in the raw materials is reduced and the cost is saved by regulating and controlling the positions of all groups of raw material powder during smelting, and meanwhile, the ordering of magnetocrystalline units during magnetizing after the low-coercivity MIM powder is formed is improved through multi-stage and multi-section sintering and multi-stage and multi-section aging, so that it is guaranteed that the MIM samarium-cobalt magnet obtains high magnetic performance.

The invention relates to the technical field of neodymium-iron-boron magnet production, in particular to a sintered neodymium-iron-boron magnet for preparing lanthanum-cerium-yttrium and a method of the sintered neodymium-iron-boron magnet. In the invention, the cerium element is used for replacing a praseodymium-neodymium alloy, meanwhile, the lanthanum and yttrium elements are introduced according to the proportion to generate a synergistic effect to regulate and control the structure of the high-cerium-content sintered neodymium-iron-boron magnet, the yttrium element is used for inhibiting main phase grain coarsening and improving the coercive force, and the lanthanum and yttrium elements can promote the flow of a rare earth-rich liquid phase in the sintering process and improve the diffusivity, so that the high-cerium-content sintered neodymium-iron-boron magnet is obtained. The density is improved.

The invention discloses a low-coercivity magnetically soft alloy and a preparation method thereof, belongs to the technical field of magnetically soft alloys, and solves the problem of poor coercivity and strength matching in the prior art. The low-coercivity magnetically soft alloy comprises the following components in percentage by mass: less than or equal to 0.01% of C, 0.50-2.00% of Si, less than or equal to 0.50% of Mn, 0.30-0.80% of Al, 12.00-15.00% of Cr, less than or equal to 0.001% of S, less than or equal to 0.001% of P and the balance of Fe and other inevitable impurities. The low-coercivity magnetically soft alloy is low in coercivity and high in strength.

The invention belongs to the field of permanent magnet materials, and discloses a preparation method of a high-performance sintered neodymium-iron-boron permanent magnet based on multi-element synergistic diffusion. The method comprises the following steps: S1, preparing a sintered neodymium-iron-boron permanent magnet blank with the grain size of 3-8 microns; s2, preparing composite diffusion medium slurry, wherein the composite diffusion medium slurry comprises inner-layer diffusion medium slurry and outer-layer diffusion medium slurry; s3, a composite diffusion medium layer is coated, the drying porosity of the inner layer is 15-20%, and the drying porosity of the outer layer is 30-35%; s4, performing multi-stage thermal diffusion treatment, including pre-diffusion heat treatment, main diffusion heat treatment and post-diffusion annealing treatment; and S5, performing subsequent treatment. Through the synergistic effect of the composite diffusion medium and multi-stage thermal diffusion, uniform distribution of multiple elements is achieved, the intrinsic coercive force of the permanent magnet is improved by 20-35%, the coercive force batch fluctuation is reduced to 3% or below, the irreversible magnetic flux loss at the high temperature of 120 DEG C is reduced by 15-25%, and the permanent magnet is suitable for the fields of new energy and the like with strict requirements for magnetic performance.

The invention discloses a preparation method of a sintered neodymium-iron-boron magnet without heavy rare earth, Pr-Fe-B-M alloy is used as an auxiliary phase alloy, LRe-Fe-B-M alloy is used as a main phase alloy, the auxiliary phase alloy is used for preparing a magnet matrix and performing grain boundary diffusion at the same time, the magnet without heavy rare earth is prepared, praseodymium element is non-uniformly distributed in the magnet, and rare earth element is not uniformly distributed in the magnet. The Pr content of part of the main phase is higher than the overall average content, the crystal boundary praseodymium content is higher than the overall average content, and the magnet surface praseodymium content is higher than the overall average content. The coercive force and the temperature stability of the magnet are improved, the magnet can still keep excellent magnetic performance under the condition that Dy and Tb are not contained, heavy rare earth elements such as Dy and Tb which are scarce in resource and high in price are prevented from being used, the high performance of the magnet is guaranteed, the production cost is reduced, and the resource utilization efficiency is improved.

The invention relates to the technical field of preparation of neodymium-iron-boron materials, and discloses a high-performance neodymium-iron-boron material and a preparation method thereof, and the high-performance neodymium-iron-boron material realizes efficient permeation of heavy rare earth elements along a specific path through a grain boundary network pre-construction and gradient diffusion technology in combination with a hydrogen decrepitation and surface activation process, so that the coercive force and thermal stability of a magnet are remarkably improved. An alternating magnetic field assisted sintering and dynamic tempering process is innovatively adopted, and a magnetic field-lattice coupling effect is utilized to release microscopic stress, so that magnetic performance attenuation in a high-temperature environment is effectively inhibited. A surface protection system is fused with a grain boundary modification and composite coating technology, a multistage corrosion-resistant barrier is constructed through the synergistic effect of an intermetallic compound layer and a nano coating, and the service life of the magnet in a severe environment is greatly prolonged. According to the method, the bottleneck of mutual restriction of performance indexes in a traditional process is broken through, and collaborative optimization of coercive force strengthening, temperature stability improving and corrosion resistance is achieved on the basis of keeping the high residual magnetism characteristic.

The invention discloses a magnetic powder core and a preparation method thereof. The preparation method of the magnetic powder core comprises the four steps of preparation of gas atomization iron-silicon soft magnetic powder, insulation coating, compression molding and annealing heat treatment. The iron-silicon soft magnetic powder is prepared through a gas atomization process, so that the iron-silicon soft magnetic powder has very good soft magnetic performance and has the advantages of low price, high magnetic conductivity, high resistivity, low coercive force, low loss, stable direct current bias characteristic and good temperature stability. Then, the iron-silicon soft magnetic powder is subjected to insulation coating; due to the fact that the aerosolized iron-silicon magnetic powder base body is subjected to preheating activation, ball milling through the insulation modifier and the heat treatment process, the magnetic conductivity and the insulation performance of the obtained iron-silicon powder product are improved in a coordinated mode; and after compression molding and annealing heat treatment, a high-temperature-resistant and corrosion-resistant magnetic powder core product is finally obtained.

To provide neodymium iron boron magnets I and II, which have excellent residual magnetic flux density, coercive force, and squareness ratio, are highly flexible in terms of adjusting composition and performance, and effectively enhance the effect of grain boundary diffusion, thereby increasing the utilization rate of heavy rare earths, and also provide a method of manufacturing the same.SOLUTION: A neodymium iron boron magnet I includes main phase crystal grains, triangular grain boundary regions, and two-grain grain boundary regions, all of which contain MB2 particles, where M is one or more selected from Nb, Zr, and Ti, and the ratio of the number of MB2 particles in each region to the number of MB2 particles in the neodymium iron boron magnet I is less than 90% in the triangular grain boundary regions, greater than 10% in the two-grain grain boundary regions and main phase crystal grains, and greater than 5% in the two-grain grain boundary regions, and the M content is 0.1 wt.% to 1.5 wt.%.SELECTED DRAWING: None

The invention discloses a preparation method of a neodymium-yttrium-iron-boron magnet with core-shell heterostructure crystal grains. The method comprises the following steps: preparing neodymium-yttrium-iron-boron rapid-quenching amorphous strips with different yttrium contents through a melting rapid-quenching technology; carrying out crystallization annealing on the amorphous rapid quenching belt at different temperatures, and preparing powder particles with the particle size of 2-5 microns through hydrogen demolishing and jet milling; and the neodymium-yttrium-iron-boron magnet with the core-shell heterostructure is prepared through high-temperature vacuum sintering after orientation forming and cold isostatic pressing of the neodymium-yttrium-iron-boron magnet in a magnetic field. According to the method, dynamic adjustment of distribution of yttrium in a crystal grain core-shell area is achieved by controlling the crystallization temperature of an amorphous rapid quenching zone, and therefore the coercive force of the magnet is improved.

The invention discloses a grain refinement process of a sintered neodymium-iron-boron magnet and the neodymium-iron-boron magnet, and belongs to the technical field of rare earth permanent magnet materials.The grain refinement process comprises the following steps that under the inert atmosphere protection condition, hyperbranched polycarbosilane is diluted with a solvent and then sprayed to the surface of low-melting-point rare earth alloy powder, and after the solvent is dried, the low-melting-point rare earth alloy powder is obtained; ndFeB alloy magnetic powder and low-melting-point rare earth alloy powder are fully and uniformly mixed and then subjected to orientation forming in a magnetic field, a blank is prepared through an isostatic pressing forming or compression molding forming process and enters a sintering furnace, heat preservation is conducted for 2-5 h at the temperature of 550-600 DEG C, and then presintering, high-temperature sintering and tempering heat treatment are conducted. The coercive force of the sintered neodymium-iron-boron magnet is improved through the technology, the coupling effect can be demagnetized to the maximum extent by combining the double-alloy technology and polycarbosilane, and meanwhile the comprehensive magnetic performance of the sintered neodymium-iron-boron permanent magnet can be improved.