WO2014079822A2

WO2014079822A2 - Magnetic material and method for producing same

Info

Publication number: WO2014079822A2
Application number: PCT/EP2013/074122
Authority: WO
Inventors: Arne Huber; Peter Barth; Jürgen OBERLE; Lars BOMMER; Gerhard Schneider; Dagmar GOLL
Original assignee: Robert Bosch Gmbh; Hochschule Aalen
Priority date: 2012-11-23
Filing date: 2013-11-19
Publication date: 2014-05-30
Also published as: WO2014079822A3; CN104981883A; CN104981883B; DE102012221448A1

Abstract

The present invention relates to a magnetic material (10), which comprises a magnetically hard phase (3) and a grain boundary phase (2), wherein the magnetically hard phase (3) is formed from a starting material which contains at least one transition metal (TM), at least one rare-earth metal (RE) and at least one additional element (X) selected from the group consisting of: B, C, N, P, W, V, Cr, Mo, Ti, Ta, Nb, Al, Cu, Ga, Si, Zr, Hf, Zn and Sn, wherein the main component part of rare-earth metal (RE) is formed from at least one element selected from the group consisting of: Ce, La, Y, Sc and Pr, and wherein the grain boundary phase (2) contains at least one heavy rare-earth metal (Z) and/or Nd.

Description

description

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Magnetic Materia! and process for its preparation prior art

The present invention relates to a magnetic material as well as two methods for producing the magnetic material.

Due to the recent increase in the use of electric motors, not least in the automotive industry and also in other applications, which have only a very limited space, the demand for high-performance magnetic materials has risen sharply in recent years. Suitable magnetic materials are those which are characterized by a high remanence, a large coercive field, which is a measure of the demagnetization of the magnetic material, as well as a large energy product, as a measure of the strength of the permanent magnet. High-performance magnetic materials of today's time also exhibit exceptional intrinsic magnetic properties and an optimized microstructure. Particularly powerful are magnetic materials, in addition to a

Transition metal also have a rare earth metal, such as Nd ₂ Fe ₄ B, which is characterized by a large spontaneous polarization, a very large crystal anisotropy, as well as a Curie temperature of about 310 ° C. However, such transition metal rare-earth magnets have disadvantages compared to conventional ferrites in terms of lower chemical, mechanical, and long-term thermal stability. In addition, these magnetic materials are compared to hard ferrites due to the

Raw material costs of the rare earth element Nd and the usually contained heavy rare earth elements Dy and / or Tb, much more expensive and difficult to obtain on the market. Because of this critical Raw material situation are more, but cheaper, rare earth Meialie, such as cerium, lanthanum or yttrium, as components of a magnetic material in the focus of materials research. However, hard magnets based on these rare earth metals usually have a lower coercive field, resulting in a lower energy product of the resulting magnetic material.

Disclosure of the invention

The magnetic material according to the invention with the features of

Claim 1 is characterized by excellent magnetic properties, and thus a high remanent magnetization, a high coercive field strength, as well as a large energy product, which predestines the magnetic material according to the invention in particular for space-reduced applications with very high power density. According to the invention, the magnetic material comprises a hard magnetic phase and a grain boundary phase, the hard magnetic phase being formed from a starting material comprising at least one transition metal (TM), at least one rare earth element (RE) and at least one additional element (X) selected from the group consisting of: boron (B), carbon (C), nitrogen (N), phosphorus (P), tungsten (W), vanadium (V), chromium (Cr), molybdenum (Mo), titanium (Ti), tantalum (Ta), niobium (Nb), aluminum (AI), copper (Cu), gallium (Ga), silicon (Si), zirconium (Zr), hafnium (Hf), zinc (Zn) and tin (Sn), and wherein the main component of rare earth element (RE) is formed from at least one element selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), scandium (Sc) and praseodymium (Pr). The grain boundary phase of the magnetic material of the present invention contains at least one heavy rare earth metal (Z) and / or neodymium (Nd). The hard magnetic phase of the magnetic material according to the invention is the sum of grains, crystals or crystallites which form this phase. It may consist of grains or crystals or crystallites of one or more defined compounds on elements or mixtures of elements. The proportions of the respective compounds or elements in the grains, crystals or crystallites may also vary. Furthermore, grains, crystals or crystallites may also comprise different compounds or elements. According to the invention contains the starting material from which the hard magnetic phase is formed, that is, in particular an alloying material produced by melting and subsequent grinding !, as the main component of the

Rare earth metal (RE) at least one element selected from the group consisting of: Ce. La, Y, Sc and Pr. The main constituent of rare earthmetal (RE) of the hard magnetic phase is that rare earth metal which has the largest weight fraction in wt .-%, based on all rare earth metals, in the

Starting material of the hard magnetic phase makes up. Due to the consequent, based on the rare earth metal part, high proportion of at least one of the elements Ce, La, Y, Sc and Pr, the raw material costs are still very high anisotropic constant and excellent coercive force of the magnetic material according to the invention over conventional rare earth metal-containing magnetic materials, significantly lower , In addition, according to the invention, the main constituent of rare earth metal (RE) is the

Hartmagnetphase used elements Ce, La, Y, Sc and Pr more readily available on the market, which greatly facilitates the procurement situation. The

Starting material, from which the hard magnetic phase of the magnetic material according to the invention is formed, and thus also the hard magnetic phase of the magnetic material also contains at least one additional element (X) selected from the group consisting of: B, C, N, P, W, V, Cr , Mo, Ti, Ta, Nb, Al, Cu, Ga, Si, Zr, Hf, Zn and Sn. The additive element (X) acts as an interstitial or substitutional additive, by which the crystal lattice of the hard magnetic phase is stabilized and / or generated by the anisotropic magnetic properties. The additive element (X) according to the invention can positively influence the magnetic properties, and in particular the coercive field strength, but also the physical and chemical properties of the magnetic material according to the invention, and thus its resistance, ie in particular its chemical and / or mechanical resistance. A grain boundary phase in the sense of the present invention is understood to mean a phase which is enriched by the enrichment of elements and / or

Compounds and / or mixtures of elements and compounds at the grain boundaries of the grains, crystals or crystallites of the hard magnetic phase is formed. According to the invention, this grain boundary phase contains at least one heavy rare earth element (Z) and / or Nd, which increases the anisotropy constant of the magnetic material and also the coercive field strength. By using heavy rare earth metals in the grain boundary phase, the beneficial effect on the anisotropy and coercivity of the magnetic material is maximized, but the raw material costs of heavy rare earth metals are well above those of Nd. On the other hand, although the Nd in the grain boundary phase causes a reduced anisotropy effect and / or coercive force effect over equal amounts of heavy rare earth elements, it is cheaper, so that a suitable material can be selected depending on the current state of raw material costs and the cost of the magnetic material of the present invention thus remain within an acceptable range with significant improvement of the magnetic

Properties of the magnetic material. Since the heavy rare earth metal (Z) and / or Nd enriched in the grain boundary phase and thus in particular Nd is not the main component of the hard magnetic phase, as in commercial permanent magnet type Nd ₂ Fe ₁ B, the proportion of heavy

Rare earth metal (Z) and / or Nd in the magnetic according to the invention

Material less and the raw material costs thus significantly lower. In addition, by a grain boundary phase containing at least one heavy rare earth metal (Z) and / or Nd, the corrosion and / or oxidation resistance of the magnetic material is remarkably improved.

Thus, the magnetic material of the present invention is high

Energy product, and therefore by an excellent remanent

Magnetization and also a very large coercive field with very good

Availability of raw materials and reduced raw material costs of the elements used according to the invention, resulting in multiple

Open application possibilities. In the inventive magnetic

Material is also achieved by the presence of heavy rare earth metal (Z) and / or Nd in the grain boundary phase in addition to a high coercive field also also a high saturation. The magnetic material according to the invention is also inexpensive to produce and in very good quality without great technical and logistical effort.

The dependent claims show preferred developments of the invention.

According to an advantageous embodiment of the invention, the heavy rare earth metal (Z) of the grain boundary phase is selected from the group consisting of Y (yttrium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium) and mixtures thereof , These heavy rare earth metals can contribute to a higher coercivity and thus contribute to increasing the

Energy product of the magnetic material according to the invention.

According to a further advantageous embodiment of the invention, the hard metal phase transition metal is selected from the group consisting of iron (Fe), cobalt (Co), manganese (Mn), nickel (Ni) and mixtures thereof, and is preferably Fe. The transition metals mentioned here form with

Rare earth metals (RE) and the additional element (X) according to the invention of the hard magnet phase particularly stable lattice structures and contribute significantly to the expression of the desired advantageous magnetic properties, ie in particular the magnetic saturation and magnetic anisotropy of the material according to the invention. Furthermore, their availability in the market is high with relatively low raw material costs, which reduces the cost of manufacturing

significantly reduced magnetic material according to the invention. The preferred use of Fe in the hard magnetic phase among the specified metals is attributable to its health and ecological safety and, moreover, to its significantly lower raw material costs compared to Co and Mn.

Further preferably, the hard magnetic phase is formed of grains, wherein a grain has a grain volume and a peripheral region R, wherein the

Boundary region R surrounds the grain volume and is disposed between the grain volume and the grain boundary phase, wherein the heavy rare earth metal (Z) of the grain boundary phase and / or Nd of the grain boundary phase in the edge region R of the grains of the hard magnetic phase is present, the thickness of the edge region R of a grain maximum 1/5 of the diameter of the

corresponding grain. It should be noted that a grain of

Hard magnetic phase according to the invention also includes crystals or crystallites.

In the context of the invention, an edge region R is thus understood to mean the region which lines the respective grains, crystals or crystallites which form the hard magnetic phase. While the grain boundary phase describes only the narrow range in which the grains, crystals or crystallites of the Hard magnetic phase adjacent to each other, the edge region R of the hard magnetic phase also includes area in the outer grain volume of the grains, Kristaiie or Kristailite. The thickness of the edge region R of a grain is at most 1/5 of the diameter of the respective grain of the hard magnetic phase, the diameter representing the length of a straight line at the widest point of the respective grain. The thickness of the edge region R and the diameter of the grains can be determined by microscopic methods such as

Transmission or Scanning Electron Microscopy, combined with

energy-dispersive and / or wavelength-dispersive X-ray spectroscopy (TEM / EDX / WDX or REM / EDX WDX).

According to a further advantageous embodiment of the invention, in the starting material of the hard magnetic phase, the content of rare earth metal (RE) of the hard magnetic phase is 5 to 40% by weight, preferably 10 to 30% by weight and / or the content of additional element (X) of hard magnetic phase 0 , 1 to 30 wt .-%, preferably 0.5 to 25 wt .-%, each based on the total weight of the starting material of the hard magnetic phase, the remainder of which is formed by the transition metal (TM). Is in the starting material, the proportion of rare earth element (RE) of the hard magnetic phase at least 5 wt .-% and preferably at least 10 wt .-% and / or the proportion of additional element (X) of the hard magnetic phase at least 0.1 wt .-% and preferably at least 0.5% by weight, a stable, high performance magnetic material is obtained which has a very low content of commonly used expensive rare earth metals, such as Nd, and yet has excellent magnetic properties and, in particular, a high remanent

Magnetization and high coercivity, and consequently also a very good energy product. Higher contents of rare earthmetal (RE) of

Hard magnetic phase of more than 30 wt .-% and in particular more than 40 wt .-% and / or higher contents of additional element (X) of the hard magnetic phase of more than 25 wt .-% and in particular more than 30 wt .-% effect no further significant increase in remanent magnetization and

Coercive force, generally lower the remanent magnetization and increase the raw material cost of the inventive magnetic material over measure. The respective contents of the components of Hartmagnethase can be determined by means of ICP-OES (inductively coupled plasma-optical emission spectrometry). Further preferably, the magnetic Materia invention! characterized in that the content of heavy rare earth metal (Z) and / or Nd in the grain boundary phase is 10 to 100% by weight, preferably 50 to 75% by weight, based on the total weight of the grain boundary phase. Accordingly, according to the invention, the grain boundary phase exclusively from the heavier. Rare earth metal (Z) and / or Nd exist, but may also contain other elements or compounds, such as other rare earth metals, such as those already contained in the hard magnetic phase. However, it is advantageous if the proportion of heavy rare earth metal (Z) and / or Nd in the

Grain boundary phase at least 10 wt .-% and preferably at least 50 wt .-% based on the total weight of the grain boundary phase.

As a result, a very high coercive force of the magnetic material according to the invention, as well as an excellent energy product and a high magnetic saturation can be achieved. However, the higher the content of heavy rare earth metal (Z) and / or Nd in the grain boundary phase, the more expensive the raw material cost of the magnetic material. In addition, from a content of heavy rare earth metal (Z) and / or Nd of more than 75 wt .-% in the grain boundary phase based on the total weight of

Grain boundary phase, no further, the magnetic properties of the magnetic material significantly increasing effects can be achieved. The respective contents of the components can be determined by means of ICP-OES (inductively coupled plasma-optical emission spectrometry).

According to another preferred embodiment, the magnetic material has at least one of the following crystal structures: RE ₂ TM ₁₄ X, RE (TM, X) ₁₂ , RE ₂ (TM, X) ₁₇ , RE (TM, X) ₅ and RE ₃ ( TM, X) ₂₉ . These crystal structures yield stable crystal lattices with the element combination essential to the invention, so that not only the magnetic properties of the magnetic material according to the invention, but also its mechanical and chemical stability are optimized.

Further preferably, the magnetic material according to the invention is characterized in that the Komvolumen and the edge region R of the grains of the hard magnetic phase have the same crystal structure, wherein in the grain volume less than 50 atom%, preferably less than 30 atom% and especially preferably less than 10 atom% of the rare earth metal (RE) of the

Hard magnetic phase are substituted by the heavy rare earth metal (Z) of the grain boundary phase and / or Nd of the grain boundary phase and wherein in the edge region R at least 10 atomic%, preferably at least 30 atomic% and particularly preferably at least 50 atomic% of the rare earth metal (RE) of

Hard magnetic phase are substituted by the heavy rare earth metal (Z) of the grain boundary phase and / or Nd of the grain boundary phase, wherein the

Degree of substitution refer to the composition of the starting material of the hard magnetic phase. A magnetic material produced, for example, by pressing and sintering a starting material usually has at least two crystal structures, namely one in the grains of the

Hard magnetic phase and another in the grain boundary phase. The grains which form the hard magnetic phase are preferably formed by a grain volume and an edge region R bordering the respective grain volume, the grain volume and the edge region R having the same crystal structure. This also includes the case that different grains with different

Crystal structures are present, in which case each of their grain volume and its associated edge region have the same crystal structures depending on the composition of the grain. Depending on the production of the magnetic material according to the invention, the heavy rare earth metal (Z) and / or Nd first reaches the grain boundary phase by diffusion. As a result of further diffusion, the heavy rare earth metal (Z) and / or Nd of the grain boundary phase preferably also diffuses into the edge region and the grain volume of the grains of the hard magnetic phase. Here it substitutes the rare earth element (RE) of the

Hard magnetic phase, so it takes place in the crystal structure of the hard magnetic grains in place of the rare earth element (RE) of the hard magnetic phase, wherein the rare earth element (RE) of the hard magnetic phase diffuses into the grain boundary phase. The diffusion and thus also the degree of substitution of the rare earth metal can be controlled for example by suitable temperature treatment of the magnetic material. Preferably, the degree of substitution of the

Rare earth metal (RE) by the heavy rare earth element (Z) of the

Grain boundary phase and / or Nd of grain boundary phase in the grain volume less than 50 at%, preferably less than 30 at% and more preferably less than 10 at%, since the grain volume has a less strong influence on the expression of the coercive force of the magnetic material and the heavy rare earth metal (Z) of the grain boundary phase and / or Nd of the Grain boundary phase here only increases the cost of the magnetic material. In addition, heavy rare earth metals such as Dy usually lower the saturation polarization of the magnetic material because they couple antiparallel to the transition metal atoms. This can be particularly well avoided by the heavy side earth metal (Z) of the grain boundary phase and / or Nd of the grain boundary phase mainly the rare earth element (RE) of the

Hard magnetic phase in the edge region R of the grains of the hard magnetic phase substituted. Here, a degree of substitution of at least 10 at%, preferably at least 30 at% and more preferably at least 50 at%, is particularly advantageous for increasing the coercive force of the magnetic material.

Due to the very high energy product, the high remanent magnetization, as well as the high anisotropy of the magnetic material according to the invention, this is particularly suitable for the production of permanent magnets for use in space-reduced applications that require a high energy density, such as electrical machines, such as in particular

Generators, motor vehicles, starters, electric motors, speakers or microelectromechanical systems containing the magnetic material according to the invention, in particular in the form of at least one permanent magnet comprising such a magnetic material. The for the

Magnetic material according to the invention described advantages, advantageous effects and preferred embodiments are also applied to such an electric machine.

Further according to the invention, two methods for producing the magnetic material according to the invention are described. A first method comprises the steps:

- Applying a layer comprising at least one heavy

Rare earth metal (Z) and / or Nd on a surface of a

Hard magnetic phase,

Heating the layer and

at least partially, preferably completely, diffusing the heavy rare earth metal (Z) and / or Nd into a grain boundary phase and / or into an edge region R and / or a grain volume of grains the hard magnetic phase of the magnetic material, wherein the thickness of the edge region R of a grain is at most 1/5 of the diameter of the corresponding grain. By this method is achieved that at least one heavy

Rare earth metal (Z) and / or Nd in the grain boundary phase and / or in a peripheral region R and / or in a grain volume of grains of

Hard magnetic phase of a specific composite magnetic material is enriched, whereby an optimum of good hard magnetic

Characteristics, ie a high coercive force, high magnetic saturation and high energy product can be achieved. For this purpose, first on a surface of a hard magnetic phase, a layer, the at least one heavy rare earth metal! (Z) and / or Nd, which also includes mixtures of heavy rare earth metals and / or Nd, applied. By heating to a suitable temperature of the magnetic material provided with the layer, which is in the form of a hard magnetic phase, preferably to a temperature of about 500 to 1000 ° C, the grain boundary phase is softened. As a result, the heavy rare earth metal (Z) and / or Nd dissolves particularly at the contact areas to the grain boundary phase, whereby the heavy rare earth metal (Z) and / or Nd diffuses into the grain boundary phase of the magnetic material. Suitable temperatures are in particular those just above the melting point of the grain boundary phase, since this promotes the diffusion rate of the heavy rare earth metal (Z) and / or Nd into the grain boundary phase and thus preferably also into the edge region and / or the grain volume of the grains of the hard magnetic phase. Thus, a high-performance magnetic material having excellent anisotropy, high coercive force, high remanent magnetization, and large energy product is provided in a simple and inexpensive manner.

An edge region R in the sense of the first method according to the invention is understood to be the region which lines the respective grains, crystals or crystallites which form the hard magnetic phase. While the grain boundary phase describes only the narrow region in which the grains, crystals or crystallites of the hard magnetic phase adjoin each other, the peripheral region R of the hard magnetic phase also includes the area in the outer grain volume of the grains, crystals or crystallites. The thickness of the edge region R of a grain is at most 1/5 of the diameter of the respective grain of the hard magnetic phase, the diameter representing the length of a straight line at the widest point of the respective grain. The thickness of the edge region R and the diameter of the grains can be determined by microscopic methods such as

Transmission or Scanning Electron Microscopy, combined with

energy-dispersive and / or wavelength-dispersive X-ray spectroscopy (TEM / EDX / WDX or REM / EDX / WDX).

The advantageous properties, effects and embodiments described for the magnetic material according to the invention also apply to the first method according to the invention for producing such a magnetic material.

Preferably, the inventive method is characterized in that the layer comprising at least one heavy rare earth metal (Z) and / or Nd by means of PVD, CVD, dip-coating or spin-coating on the

Surface of the hard magnetic phase is applied. This can be done in a conventional manner by using, for example, organometallic

Precursor compounds, alloys or fluorine, oxygen, or

Hydrogen-containing compounds, take place.

Further preferably, the grain boundary phase is at least partially, preferably completely, liquid during the diffusion of the heavy rare earth metal (Z) and / or Nd. This increases the diffusion rate of the heavy rare earth metal (Z) and / or Nd along the grain boundaries and even promotes enrichment of this heavy rare earth element (Z) and / or Nd in a peripheral region R and / or possibly also in the grain volume of the grains

Hard magnetic phase, as described above.

A second method according to the invention for producing a magnetic material as described above comprises the steps of: mixing at least one alloy a) and at least one

Alloy b), wherein the alloy a) at least one transition metal (TM), at least one rare earth element (RE) and at least one

Additive element (X) selected from the group consisting of: B, C, N, P, W, V, Cr, Mo, Ti, Ta, Nb, Al, Cu, Ga, Si, Zr, Hf, Zn and Sn, contains wherein the main rare earth element (RE) is formed of at least one member selected from the group consisting of Ce, La, Y, Sc and Pr, and wherein the alloy b) contains at least one heavy rare earth element (Z) and / or Nd in which the content of heavy rare earth metal (Z) and / or Nd in the alloy b) is at least 10% by weight, preferably at least 30% by weight and particularly preferably at least 50% by weight, based on the

Total weight of the alloy b), is

Alignment of the mixture of alloy a) and alloy b) in

magnetic field

Pressing and sintering the mixture of alloy a) and alloy b), wherein the sintering temperature is selected such that a

hard magnetic material comprising a hard magnetic phase of grains of the alloy a) and an inter-grain boundary phase, and wherein the heavy rare earth metal (Z) and / or Nd of the alloy b) at least partially, preferably fully, in the grain boundary phase and / or or diffused into an edge region R and / or into a grain volume of the grains of the hard magnetic phase of the magnetic material, wherein the thickness of the edge region R of a grain is at most 1/5 of the diameter of the corresponding grain.

The alloys a) and b) in this case represent the starting material of the hard magnetic material to be formed and are prepared and provided in the usual way. The mixing of the alloys is carried out in a conventional manner in quantities corresponding to the specified

Composition of the resulting hard magnetic phase correspond. The alloy a), including several alloys a), is characterized by a composition comprising at least one transition metal (TM), at least one rare earth element (RE) and at least one additional element (X) selected from the group consisting of: B, C, N, P, W, V, Cr, Mo, Ti, Ta, Nb, Al, Cu, Ga, Si, Zr, Hf, Zn and Sn, wherein the main constituent of rare earth metal (RE) is at least an element selected from the group consisting of: Ce, La, Y, Sc and Pr. The alloy b), so also several alloys b) draws or is characterized by a Content of heavy rare earth metal (Z) and / or Nd of at least 10% by weight, preferably at least 30% by weight and more preferably at least 50% by weight, based in each case on the total weight of the alloy b). After mixing the alloy a) and the alloy b) carried out in a known manner alignment in the magnetic field, as well as a compression of the mixture of alloy a) and alloy b). This is followed by a sintering step of the pressed alloy mixture, in which the sintering temperature

is selected according to the alloy materials so that a

hard magnetic material is formed, which is a hard magnetic phase (3) of grains of the alloy a) and a lying between the grains

Grain boundary phase contains. The heavy contained in alloy b)

Furthermore, rare earth metal (Z) and / or Nd diffuses at least partially, preferably completely, into the grain boundary phase and / or into an edge region R and / or into a grain volume of the grains of the hard magnetic phase of the magnetic material by the sintering at an appropriate temperature, the thickness of the edge region R of a grain maximum 1/5 of the

Diameter of the corresponding grain makes. The grain boundary phase is preferably formed predominantly from alloy b) or else by a diffusion exchange of the grain boundary phase already contained in alloy a) with alloy b). By appropriate temperature treatment, the heavy rare earth metal (Z) of the grain boundary phase and / or Nd of the grain boundary phase can also be surrounded in that of the edge region R.

Grain volume of the grains of hard magnetic phase penetrate. However, this is not desirable for the reasons mentioned above. By diffusing the heavy rare earth metal (Z) and / or Nd at least into the

Grain boundary phase and preferably also in the edge region R of the grains, the coercive force of the resulting magnetic material is significantly increased.

Under an edge region R in the sense of the second invention

Process is understood to mean the region that lines the respective grains, crystals or crystallites forming the hard magnetic phase. While the

Grain boundary phase describes only the narrow range in which the grains, crystals or crystallites of the hard magnetic phase adjacent to each other, the edge region R of the hard magnetic phase also includes area in the outer Kornvoiumen of grains, Kristaiie or Kristaiiite. The thickness of the edge region R of a grain is at most 1/5 of the diameter of the respective grain of the hard magnetic phase, the diameter representing the length of a straight line at the widest point of the respective grain. The thickness of the edge region R and the diameter of the grains can be determined by microscopic methods such as transmission or scanning electron microscopy combined with energy dispersive and / or wavelength dispersive X-ray spectroscopy (TEM / EDX WDX or REM / EDX / WDX).

The advantageous properties, effects and embodiments described for the magnetic material according to the invention also apply to the second method according to the invention for producing such a magnetic material.

Further preferably, the sintering temperature is selected such that the grain boundary phase that forms is at least partially, preferably completely, liquid during the diffusion of the heavy rare earth metal (Z) and / or Nd. This in turn increases the diffusion rate of the heavy rare earth element (Z) and / or Nd along the grain boundaries, and further promotes the accumulation of this heavy rare earth element (Z) and / or Nd in the peripheral region R of the hard magnetic phase grains as described above. It should be noted that the two methods according to the invention for

Preparation of the magnetic material according to the invention described herein are suitable.

Brief Description of the Drawings An embodiment of the invention will now be described in detail with reference to the accompanying drawings. In the drawing is:

Figure 1 is a schematic representation of the microstructure of a

preferred embodiment of the magnetic material according to the invention before temperature treatment and

Figure 2 is a schematic representation of the microstructure of a

preferred embodiment of the magnetic material according to the invention after temperature treatment. Embodiment of the invention

FIG. 1 shows a schematic representation of the microstructure of a preferred embodiment of the magnetic material 10 according to the invention before temperature treatment. The material 10 according to the invention contains grains 1 of a hard magnetic phase 3, which are at least partially separated from each other by a grain boundary phase 2, which causes a magnetic decoupling of the individual grains and thus a high coercive force of the magnetic material. By means of a suitable method, a layer 4 of a heavy rare earth metal (Z) and / or Nd was applied to a surface of the hard magnetic phase 3. At this stage, grain boundary phase 2 does not yet contain heavy rare earth metal (Z) or Nd.

FIG. 2 shows a schematic illustration of the microstructure of a preferred embodiment of the magnetic material 10 according to the invention after temperature treatment. That The magnetic material 10 of Figure 1 was heated to a temperature of about 500 to 1000 ° C, so that the

Grain boundary phase 2 was partially liquefied. The heavy rare earth element (Z) and / or Nd initially applied (see FIG. 1) as layer 4 to the surface of the hard magnetic phase 3 then diffused along the

Grain boundary phase 2 in the magnetic material 10 a. In addition, it partially diffused into the grain volume of the magnetic material 10, namely in a peripheral region R, which made a thickness of at most 1/5 of the diameter D of the respective grain 1 of the hard magnetic phase 3, wherein the diameter D is the length of a straight line at the widest Represents the location of each grain.

The magnetic material formed in this way is characterized by excellent magnetic properties, in particular by a high coercive force, a high magnetic saturation and a very good

Energy product out. In addition, the raw material and manufacturing costs of

magnetic material due to the inventive combination of transition metal (TM), rare earth metal (RE), additional element (X), and heavy rare earth metal (Z) and / or Nd, compared to conventional

Transition metal rare earth magnets, significantly reduced.

Claims

May include netic material

a hard magnetic phase (3) and

a grain boundary phase (2), wherein

the hard magnetic phase (3) is formed from a starting material comprising at least one transition metal (TM), at least one

Rare earth element (RE) and at least one additive element (X) selected from the group consisting of: B, C, N, P, W, V, Cr, Mo, Ti, Ta, Nb, Al, Cu, Ga, Si, Zr , Hf, Zn and Sn, wherein the main rare earth element (RE) is formed of at least one member selected from the group consisting of Ce, La, Y, Sc and Pr, and wherein

the grain boundary phase (2) contains at least one heavy rare earth element (Z) and / or Nd.

Magnetic material according to claim 1, characterized in that the heavy rare earth element (Z) of the grain boundary phase (2) is selected from the group consisting of: Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof.

Magnetic material according to claim 1 or 2, characterized in that the transition metal (TM) of the hard magnetic phase (3) is selected from the group consisting of: Fe, Co, Mn, Ni and mixtures thereof.

Magnetic material according to one of the preceding claims, characterized in that the hard magnetic phase (3) consists of grains (1), wherein a grain (1) has a grain volume and an edge region R, wherein the edge region R surrounds the grain volume and between the grain volume and the grain boundary phase (2) is arranged, wherein the heavy rare earth metal (Z) of the grain boundary phase (2) and / or Nd of the grain boundary phase (2) in the edge region R of the grains (1) of the hard magnetic phase (3) is present, wherein the thickness of Edge area R of a grain (1) maxima! 1/5 of the diameter of the corresponding grain (1).

Magnetic material according to one of the preceding claims, characterized in that in the starting material of

Hard magnetic phase (3) the content of rare earth metal (RE) of

Hard magnetic phase 5 to 40 wt .-%, preferably 10 to 30 wt .-% and / or the content of additional element (X) of the hard magnetic phase 0.1 to 30 wt .-%, preferably 0.5 to 25 wt .-%, each based on the total weight of the starting material of the hard magnetic phase (3), and the balance thereof is formed by the transition metal (TM).

Magnetic material according to one of the preceding claims, characterized in that the content of heavy rare earth metal (Z) in the grain boundary phase (2) and / or Nd in the grain boundary phase (2) 10 to 100 wt .-%, preferably 50 to 75 wt. %, based on the total weight of the grain boundary phase (2).

Magnetic material according to one of the preceding claims, characterized in that the magnetic material (10) has at least one of the following crystal structures: RE ₂ TM ₄ X, RE (TM, X) ₁₂ , RE ₂ (TM, X) ₁₇ , RE ( TM, X) ₅ and RE ₃ (TM, X) ₂₉ .

Magnetic material according to one of claims 4 to 7, characterized in that the grain volume and the edge region R have the same crystal structure, wherein in the grain volume less than 50 atomic%, preferably less than 30 atomic% and particularly preferably less than 10 atomic% of the rare earth metal (RE) of the hard magnetic phase (3) are substituted by the heavy rare earth metal (Z) of the grain boundary phase (2) and / or Nd of the grain boundary phase (2) and wherein at the edge region R at least 10 atomic%, preferably at least 30 atomic% and particularly preferably at least 50 atomic% of the rare earth element (RE) of the hard magnetic phase (3) is substituted by the heavy rare earth metal (Z) of the grain boundary phase (2) and / or Nd of the grain boundary phase (2), the degrees of substitution being based on the composition of the grain boundary phase (2) Obtain starting material of the hard magnetic phase (3). A method of making a magnetic material (10) according to any one of the preceding claims comprising the steps of:

Applying a layer (4) comprising at least one heavy side earth metal (Z) and / or Nd to a surface of a

Hard magnetic phase (3),

Heating the layer (4) and

at least partially, preferably completely diffusing the heavy rare earth metal (Z) and / or Nd into one

Grain boundary phase (2) and / or in an edge region R and / or a grain volume of grains (1) of the hard magnetic phase (3) of the magnetic material (10), wherein the thickness of the edge region R of a grain at most 1/5 of the diameter of the corresponding grain (1).

L 5

10. The method according to claim 9, characterized in that the layer (4) comprising at least one heavy rare earth metal (Z) and / or Nd by means of PVD, CVD, dip-coating or spin-coating on the surface of the hard magnetic phase (3) is applied ,

20

1. The method according to any one of claims 9 or 10, characterized in that the grain boundary phase (2) during the Eindiffundens heavy heavy earth metals (Z) and / or Nd at least partially, preferably completely, is liquid.

25

A method of making a magnetic material (10) according to any one of claims 1 to 8, comprising the steps of:

Mixing at least one alloy a) and at least one alloy b), wherein the alloy a) at least one

Transition metal (TM), at least one rare earth element (RE) and at least one additional element (X) selected from the group consisting of: B, C, N, P, W, V, Cr, Mo, Ti, Ta, Nb, Al, Cu, Ga, Si, Zr, Hf, Zn and Sn, wherein the main component of

Rare earth element (RE) is formed from at least one element selected from the group consisting of: Ce, La, Y, Sc and Pr, and wherein the alloy b) is at least one heavy rare earth element (Z) and / or Nd, wherein the content of heavy

Rare earth metal (Z) and / or Nd in the alloy b) at least 10 wt .-%, preferably at least 30 wt .-% and particularly preferably at least 50 wt .-%, each based on the

Total weight of the alloy b), is

Alignment of the mixture of alloy a) and alloy b) in the magnetic field

Pressing and sintering the mixture of alloy a) and alloy b), wherein the sintering temperature is selected to form a hard magnetic material comprising a hard magnetic phase (3) of grains (1) of the alloy a) and one between the grains (1 and the heavy rare earth element (Z) and / or Nd of the alloy b) at least partially, preferably completely in the grain boundary phase (2) and / or in an edge region R and / or a grain volume of the grains (1) the hard magnetic phase (3) of the magnetic material (10) diffuses in, wherein the thickness of the edge region R of a grain (1) at most 1/5 of the diameter of the corresponding grain (1).

A method according to claim 12, characterized in that the

Sintering temperature is chosen so that the forming

Grain boundary phase (2) is at least partially, preferably completely, liquid during the diffusion of the heavy rare earth metal (Z) and / or Nd.