WO2018111188A1

WO2018111188A1 - Alloy compositions, magnetic materials, bonded magnets and methods for producing the same

Info

Publication number: WO2018111188A1
Application number: PCT/SG2016/050609
Authority: WO
Inventors: Yong Keat LIM
Original assignee: Neo Performance Materials (Singapore) Pte Ltd
Priority date: 2016-12-16
Filing date: 2016-12-16
Publication date: 2018-06-21
Also published as: CN108475567A; CN108475567B

Abstract

The present invention relates to an alloy composition of Formula (I): RE_x-Fe_100-x-y-z-B_y-M_z, wherein RE is two or more rare earth metals, M is one or more refractory metals, x, y and z are atom% in which 10.5Ρ≤x≤14, 5.5≤y≤6.5 and 0.5≤z≤1.5. One composition specified in this invention is of Formula (II): [(Pr_aNd_(1-a))_bCe_1-b]_x-Fe_100-x-y-z-B_y-M_z, wherein a and b are 0.20≤a≤0.50 and 0.40≤b≤1.00. The present invention also relates to magnetic materials, bonded magnets comprising them and methods of producing said bonded magnets.

Description

Title of Invention: Alloy Compositions, Magnetic Materials, Bonded Magnets and Methods for Producing the Same

Technical Field

The present invention generally relates to alloy compositions, magnetic materials, and bonded magnets. The present invention also relates to a method for producing such alloy compositions, magnetic materials and bonded magnets.

Background Art Bonded magnets, such as rare-earth based magnets are used in numerous applications, including computer hardware, automobiles, consumer electronics and household appliances. Such magnets are required to have good resistance to demagnetization at elevated temperatures, for example when used in electric motors in household appliances and the like, for efficient motor operation. The temperatures involved in these motor applications are typically within the range of 100 to 150 °C. Therefore, good resistance to demagnetization is required within this temperature range.

When dealing with the thermal stability of bonded magnets, conventional wisdom is generally concerned with three factors: the Curie temperature (T_c), reversible temperature coefficient of remanence (B_r), and the temperature coefficient of intrinsic coercivity (H_ci) (the two temperature coefficients are commonly known as a and β, respectively). A fourth factor, namely flux-aging loss, has often been omitted from many considerations, partly because of its complexity. Nevertheless, flux-aging loss is important to the long-term thermal stability of the magnet and to magnet circuit designs. Moreover, magnet end users also desire materials of high B_r and H_ci values and low flux-aging loss, so that the magnet will perform well when exposed to their operation temperatures for a sustained period of time.

However, conventional rare-earth based magnets suffer from irreversible losses after aging at a particular temperature. Magnet losses increase with increasing time and elevated temperature. Additionally, conventional rare earth-iron-boron magnets are costly to produce due to the scarcity of rare earth metals, such as Nd and Pr, and the instability in their supply and cost.

Cerium (Ce) is a more abundant and lower-cost rare earth metal. However, known Nd- Fe magnets comprising Ce suffer from reduced thermal stability and increased flux ageing loss. These known problems with using Ce in such magnets have led to magnet producers having concerns about selecting cerium-containing materials because of the risk of lower ageing performance.

There is therefore a need to provide a magnetic material that overcomes, or at least ameliorates, one or more of the disadvantages described above. There is a need to provide a magnetic material that may be used in the manufacture of magnets having high resistance to demagnetization at elevated temperatures within the range of 100 to 150 °C.

There is also a need to provide a magnetic material of low cost.

Summary of Invention

The present disclosure relates to rare-earth based alloy compositions, magnetic materials and bonded magnets with improved thermal stability and low flux ageing loss. The present disclosure also relates to a method for producing such alloy compositions, magnetic materials and bonded magnets. The bonded magnets may exhibit high values of H_ci which remain high even at elevated temperature. Desired H_ci values may be achieved by adjusting the rare earth content and/or refractory metal components of the bonded magnet.

According to a first aspect of the present disclosure, there is provided an alloy composition of Formula (I):

RE_x-Feioo-x-y-z-B_y-M_z - Formula (I) wherein:

RE is two or more rare earth metals selected from the group consisting of La, Ce, Pr, Nd, Y, Sm, Gd, Tb, Dy, Ho, and Yb; M is a one or more refractory metals selected from the group consisting of Zr, Nb, Mo, Ti, V, Cr, Mn, Hf, Ta and W; and x, y and z are atom% in which 10.5≤x≤14, 5.5≤y≤6.5 and 0.5≤z≤1.5, optionally wherein 0.1 atom% to 10 atom% of Fe may be substituted with cobalt. There is also disclosed an alloy composition, wherein the composition is of Formula (II):

[(Pr_aNd₍i-_a))_bCei-_b]_x-Feioo-x-y-z-B_y-M_z -- Formula (II) wherein:

M is a one or more refractory metals selected from the group consisting of Zr, Nb, Mo, Ti, V, Cr, Mn, Hf, Ta and W; a and b are 0.20≤a≤0.50 and 0.40≤b<1 .00; and x, y and z are atom% in which 10.5≤X≤14, 5.5≤y≤6.5 and 0.5≤z≤1.5, optionally wherein 0.1 atom% to 10 atom% of Fe may be substituted with cobalt.

In a second aspect of the present disclosure, there is provided a magnetic material comprising the alloy composition as disclosed herein.

In a third aspect of the present disclosure, there is provided a bonded magnet comprising the alloy composition or magnetic material as disclosed herein.

Advantageously, the disclosed bonded magnets may exhibit improved thermal stability.

Advantageously, the disclosed bonded magnets may exhibit high intrinsic coercivity (H_ci) values even when measured at high temperatures, for example, temperatures higher than 100 °C.

Advantageously, the disclosed bonded magnets may exhibit low flux ageing loss. This advantageously allows the disclosed bonded magnets to exhibit good resistance to demagnetization at elevated temperatures which allows for their use in high temperature environments. Further advantageously, the disclosed bonded magnets may comprise cerium while still maintaining good thermal stability, low flux ageing loss and high H_ci when measured at high temperatures.

Also advantageously, the disclosed alloy compositions may be produced with low cost.

In a fourth aspect of the present disclosure, there is provided a method of making a bonded magnet, the method comprising the following steps:

(i) forming a melt comprising a composition of Formula (I):

RE_x-Feioo-x-y-z-B_y-M_z -- Formula (I) wherein:

RE is two or more rare earth metals selected from the group consisting of La, Ce, Pr, Nd, Y, Sm, Gd, Tb, Dy, Ho, and Yb;

M is a one or more refractory metals selected from the group consisting of Zr, Nb, Mo, Ti, V, Cr, Mn, Hf, Ta and W; and x, y and z are atom% in which 10.5≤x≤14, 5.5≤y≤6.5 and 0.5≤z≤1.5, optionally wherein 0.1 atom% to 10 atom% of Fe may be substituted with cobalt;

(ii) solidifying the melt, thereby obtaining a magnetic powder;

(iii) thermally annealing the magnetic powder;

(iv) mixing the magnetic powder with a binding agent; and

(v) pressing the magnetic powder and the binding agent to form the bonded magnet.

In a fifth aspect of the present disclosure, there is provided a method of making a bonded magnet, the method comprising the following steps:

(i) forming a melt comprising a composition of Formula (II):

[(Pr_aNd₍i-_a))_bCei-_b]_x-Feioo-x-y-z-B_y-M_z -- Formula (II) wherein:

M is a one or more refractory metals selected from the group consisting of Zr, Nb, Mo, Ti, V, Cr, Mn, Hf, Ta and W; a and b are 0.20≤a≤0.50 and 0.40≤b<1 .00; and x, y and z are atom% in which 10.5≤x≤14, 5.5≤y≤6.5 and 0.5≤z≤1.5, optionally wherein 0.1 atom% to 10 atom% of Fe may be substituted with cobalt;

(ii) solidifying the melt, thereby obtaining a magnetic powder;

(iii) thermally annealing the magnetic powder;

(iv) mixing the magnetic powder with a binding agent; and

In a sixth aspect of the present disclosure, there is provided a method of making a bonded magnet, the method comprising the following steps:

(i) forming a melt comprising a composition as disclosed herein;

(ii) solidifying the melt, thereby obtaining a magnetic powder;

(iii) thermally annealing the magnetic powder;

(iv) mixing the magnetic powder with a binding agent; and

In a seventh aspect of the present disclosure, there is provided a bonded magnet obtainable or obtained by a method as disclosed herein. Definitions

The following are some definitions that may be helpful in understanding the description of the present invention. These are intended as general definitions and should in no way limit the scope of the present invention to those terms alone, but are put forth for a better understanding of the following description.

The terms "flux-ageing loss" or "ageing performance" or "ageing loss" as used herein refers to the loss of magnetic flux of a magnet after being exposed at a specific temperature and for a specific period of time.

The term "rare earth metal" as used herein refers to a rare earth element and may be cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb) and yttrium (Y).

The term "refractory metal" as used herein refers to a metal having a high melting point, preferably more than about 1200 °C. Suitable refractory metals may be zirconium (Zr), niobium (Nb), molybdenum (Mo), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), hafnium (Hf), tantalum (Ta), tungsten (W), or combinations thereof.

The word "substantially" does not exclude "completely" e.g. a composition which is "substantially free" from Y may be completely free from Y. Where necessary, the word "substantially" may be omitted from the definition of the invention. Unless specified otherwise, the terms "comprising" and "comprise", and grammatical variants thereof, are intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, unrecited elements.

As used herein, the term "about", in the context of concentrations of components of the formulations, typically means +/- 5% of the stated value, more typically +/- 4% of the stated value, more typically +/- 3% of the stated value, more typically, +/- 2% of the stated value, even more typically +/- 1 % of the stated value, and even more typically +/- 0.5% of the stated value.

Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed ranges. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1 , 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Certain embodiments may also be described broadly and generically herein. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the disclosure. This includes the generic description of the embodiments with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein.

Detailed Disclosure of Embodiments

As discussed above, bonded magnets, such as rare-earth based magnets are used in numerous applications, including computer hardware, automobiles, consumer electronics and household appliances. Such magnets are required to have good resistance to demagnetization at elevated temperatures. However, conventional rare-earth based magnets are costly to produce due to the scarcity of rare-earth metals, such as Nd and Pr, and the instability in their supply and cost. Therefore, there is a need for bonded magnets which exhibit good resistance to demagnetization at elevated temperatures and are also cost-efficient to produce. Resolving the interplay between these two requirements has so far proved challenging.

The inventors of the present invention have surprisingly found that the ageing performance of a bonded magnet is strongly correlated to its H_ci value. It was discovered that to achieve low flux ageing loss, H_ci must remain high at elevated temperature. It was therefore found that to achieve good ageing performance, H_ci≥ 9.5 kOe at 24 °C or H_ci≥ 6.5 kOe at 120 °C are desirable.

The bonded magnets of the present invention advantageously exhibit a unique low β coefficient (percentage loss in H_ci per degree temperature rise). A low β coefficient indicates that the H_ci value is retained at elevated temperatures and therefore contributes to improved ageing performance. The inventors have surprisingly found that by adjusting the rare earth content of a bonded magnet, bonded magnets with improved ageing performance may be achieved. Further, being able to adjust the rare earth content of a bonded magnet would allow the use of cheaper and more abundant rare earth metals to be used which would result in significant cost savings in the raw materials required to produce such bonded magnets.

The inventors have therefore found that specific combinations and types of rare-earth metals in bonded magnets may lead to bonded magnets exhibiting high H_ci values, which remain high at elevated temperatures. These bonded magnets may further exhibit low β coefficients which mean that H_ci value is retained at elevated temperatures and therefore contribute to improved ageing performance.

The inventors have also surprisingly found that by including a refractory metal, bonded magnets with improved ageing performance may be achieved. The inventors have found that desired H_ci values may be achieved by including specific amounts of refractory metal, which remain high at elevated temperatures. These bonded magnets may further exhibit low β coefficients which mean that H_ci value is retained at elevated temperatures and therefore contribute to improved ageing performance.

The inventors have further found that bonded magnets with a specific amounts and types of rare earth metal in combination with specific amounts and types of refractory metals exhibit H_ci values which remain high at elevated temperatures. These bonded magnets may further exhibit low β coefficients which mean that H_ci value is retained at elevated temperatures and therefore contribute to improved ageing performance.

Exemplary, non-limiting embodiments of the disclosed alloy compositions, magnetic materials, bonded magnets, and methods of making the same, will now be disclosed.

The present invention provides an alloy composition of Formula (la): RE_x-Feioo-x-y-z-B_y-M_z - Formula (la) wherein:

RE is one or more rare earth metals selected from the group consisting of La, Ce, Pr, Nd, Y, Sm, Gd, Tb, Dy, Ho, and Yb; M is a one or more refractory metals selected from the group consisting of Zr, Nb, Mo, Ti, V, Cr, Mn, Hf, Ta and W; and x, y and z are atom% in which 10.5≤x≤14, 5.5≤y≤6.5 and 0.5≤z≤1.5.

The present invention also provides an alloy composition of Formula (I): RE_x-Fe₁₀o-x-y-z-B_y-M_z -- Formula (I) wherein:

M is a one or more refractory metals selected from the group consisting of Zr, Nb, Mo, Ti, V, Cr, Mn, Hf, Ta and W; and x, y and z are atom% in which 10.5≤x≤14, 5.5≤y≤6.5 and 0.5≤z≤1.5, optionally wherein 0.1 atom% to 10 atom% of Fe may be substituted with cobalt.

RE may be one, two or more rare earth element(s) such as lanthanum (La), cerium (Ce), praseodymium, (Pr), neodymium (Nd), yttrium (Y), samarium (Sm), and gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), , ytterbium (Yb), or combinations thereof. In a more specific embodiment, RE may be Nd, Pr, Ce, or combinations thereof.

The alloy composition may contain no aluminum (Al), silicon (Si), and/or copper (Cu), except as unavoidable impurities in certain situations.

RE may be one rare earth metal, two rare earth metals, three rare earth metals, four rare earth metals or five rare earth metals.

RE may be at least two rare earth metals, wherein one of the rare earth metals is Nd. RE may be at least two rare earth metals selected from the group consisting of Pr, Nd or Ce. RE may be Nd and Pr. RE may be Nd, Pr and Ce.

M may be one, two, or more refractory metal(s) such as zirconium (Zr), niobium (Nb), molybdenum (Mo), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), hafnium (Hf), tantalum (Ta), tungsten (W), or combinations thereof. In a more specific embodiment, M may be Zr, Nb, Ti, and Cr, or combinations thereof. M may be Nb. M may be Zr. M may be one refractory metal, two refractory metals, three refractory metals, four refractory metals, or five refractory metals. x may be 10.5≤x≤14. x may be from about 10.5 to about 14, from about 10.6 to about 14, from about 10.7 to about 14, from about 10.8 to about 14, from about 10.9 to about 14, from about 1 1 .0 to about 14, from about 1 1 .1 to about 14, from about 1 1 .2 to about 14, from about 1 1 .3 to about 14, from about 1 1 .4 to about 14, from about 1 1 .5 to about 14, from about 1 1 .6 to about 14, from about 1 1 .7 to about 14, from about 1 1 .8 to about 14, from about 1 1 .9 to about 14, from about 12.0 to about 14, from about 12.1 to about 14, from about 12.2 to about 14, from about 12.3 to about 14, from about 12.4 to about 14, from about 12.5 to about 14, from about 12.6 to about 14, from about 12.7 to about 14, from about 12.8 to about 14, from about 12.9 to about 14, from about 13.0 to about 14, from about 13.1 to about 14, from about 13.2 to about 14, from about 13.3 to about 14, from about 13.4 to about 14, from about 13.5 to about 14, from about 13.6 to about 14, from about 13.7 to about 14, from about 13.8 to about 14, from about 13.9 to about 14, from about 10.5 to about 13.9, from about 10.5 to about 13.8, from about 10.5 to about 13.7, from about 10.5 to about 13.6, from about 10.5 to about 13.5, from about 10.5 to about 13.4, from about 10.5 to about 13.3, from about 10.5 to about 13.2, from about 10.5 to about 13.1 , from about 10.5 to about 13.0, from about 10.5 to about 12.9, from about 10.5 to about 12.8, from about 10.5 to about 12.7, from about 10.5 to about 12.6, from about 10.5 to about 12.5, from about 10.5 to about 12.4, from about 10.5 to about 12.3, from about 10.5 to about 12.2, from about 10.5 to about 12.1 , from about 10.5 to about 12.0, from about 10.5 to about 1 1 .9, from about 10.5 to about 1 1 .8, from about 10.5 to about 1 1 .7, from about 10.5 to about 1 1 .6, from about 10.5 to about 1 1 .5, from about 10.5 to about 1 1 .4, from about 10.5 to about 1 1 .3, from about 10.5 to about 1 1 .2, from about 10.5 to about 1 1 .1 , from about 10.5 to about 1 1 .0, from about 10.5 to about 10.9, from about 10.5 to about 10.8, from about 10.5 to about 10.7, from about 10.5 to about 10.6, from about 1 1 .0 to about 12.5, from about 1 1 .3 to about 12.5, from about 1 1 .6 to about 12.5, from about 1 1 .9 to about 12.5, from about 12.2 to about 12.5, from about 1 1 .0 to about 12.2, from about 1 1 .0 to about 1 1 .9, from about 1 1 .0 to about 1 1 .6, from about 1 1 .0 to about 1 1 .3, or about 10.5, or about 10.6, or about 10.7, about 10.8, about 10.9, about 1 1 .0, about 1 1 .1 , about 1 1 .2, about 1 1 .3, about 1 1 .4, about 1 1 .5, about 1 1 .6, about 1 1 .7, 1 1 .76, about 1 1 .8, about 1 1 .9, about 12.0, about 12.1 , about 12.2, about 12.3, about 12.4, about 12.5, about 12.6, about 12.7, about 12.8, about 12.9, about 13.0, about 13.1 , about 13.2, about 13.3, about 13.4, about 13.5, about 13.6, about 13.7, about 13.8, about 13.9, about 14.0, or any range or value therein. y may be 5.5≤y≤6.5. y may be from about 5.5 to about 6.5, from 5.6 to about 6.5, from about 5.7 to about 6.5, about 5.8 to about 6.5, about 5.9 to about 6.5, about 6.0 to about 6.5, about 6.1 to about 6.5, about 6.2 to about 6.5, about 6.3 to about 6.5, about 6.4 to about 6.5, from about 5.5 to about 6.4, from about 5.5 to about 6.3, from about 5.5 to about 6.2, from about 5.5 to about 6.1 , from about 5.5 to about 6.0, from about 5.5 to about 5.9, from about 5.5 to about 5.8, from about 5.5 to about 5.7, from about 5.5 to about 5.6, or about 5.5, about 5.6, about 5.7, about 5.8, about 5.9, about 6.0, about 6.1 , about 6.2, about 6.3, about 6.4, or about 6.5, or any range or value therein. z may be 0.5≤z≤1.5. z may be from about 0.5 to about 1 .5, about 0.6 to about 1 .5, about 0.7 to about 1 .5, about 0.8 to about 1 .5, about 0.9 to about 1 .5, about 1 .0 to about 1 .5, about 1 .1 to about 1 .5, about 1 .2 to about 1 .5, about 1 .3 to about 1 .5, about 1 .4 to about 1 .5, about 0.5 to about 1 .4, about 0.5 to about 1 .3, about 0.5 to about 1 .2, about 0.5 to about 1 .1 , about 0.5 to about 1 .0, about 0.5 to about 0.9, about 0.5 to about 0.8, about 0.5 to about 0.7, about 0.5 to about 0.6, or about 0.8 to about 1 .2, or about 0.9 to about 1 .2, or about 1 .0 to about 1 .2, or about 1 .1 to about 1 .2, or about 0.8 to about 1 .1 , or about 0.8 to about 1 .0, or about 0.8 to about 0.9, or about 0.5, or about 0.6, or about 0.7, or about 0.8, or about 0.9, or about 1 .0, or about 1 .1 , or about 1 .2, or about 1 .3, or about 1 .4, or about 1 .5, or any range or value therein.

In a composition of formula (I), about 0.1 atom% to about 10 atom% of iron may be substituted with cobalt. About 0.1 atom%, 0.5 atom%, 1 .0 atom%, 2.0 atom%, 2.5 atom%, 3.0 atom%, 3.5 atom%, 4.0 atom%, 4.5 atom%, 5.0 atom%, 5.5 atom%, 6.0 atom%, 6.5 atom%, 7.0 atom%, 7.5 atom%, 8.0 atom%, 8.5 atom%, 9.0 atom%, 9.5 atom%, or about 10.0 atom% of Fe may be substituted with cobalt, or any range or value therein.

In another embodiment, the composition may contain no cobalt.

In a composition of formula (I), the values of x, y and z may be 1 1.0≤x≤12.5, 6.0≤y≤6.5 and 0.8≤z≤1.2 or any range or value therein.

The present disclosure further provides an alloy composition, wherein the composition is of Formula (II):

[( Pr_aNd₍₁ __a)) _bCei __b]_x- Fei ₀₀-x-_y-z- B_y- M_z - Formula (II) wherein: M is one or more refractory metals selected from the group consisting of Zr, Nb, Mo, Ti, V, Cr, Mn, Hf, Ta and W; a and b are 0.20≤a≤0.50 and 0.40≤b<1 .00; and x, y and z are atom% in which 10.5≤X≤14, 5.5≤y≤6.5 and 0.5≤z≤1.5, optionally wherein 0.1 atom% to 10 atom% of Fe may be substituted with cobalt.

M, x, y and z are defined as above. a may be 0.20≤b≤0.50. a may be from about 0.20 to about 0.50, about 0.25 to about 0.50, about 0.30 to about 0.50, about 0.35 to about 0.50, about 0.40 to about 0.50, about 0.45 to about 0.50, about 0.20 to about 0.45, about 0.20 to about 0.40, about 0.20 to about 0.35, about 0.20 to about 0.30, about 0.20 to about 0.25, or about 0.20, or about 0.25, or about 0.30, or about 0.35, or about 0.40, or about 0.45, or about 0.50, or any range or value therein. b may be 0.40≤b<1 .00. b may be from about 0.40 to about 1 .00, about 0.45 to about 1 .00, about 0.50 to about 1 .00, about 0.55 to about 1 .00, about 0.60 to about 1 .00, about 0.65 to about 1 .00, about 0.70 to about 1 .00, about 0.75 to about 1 .00, about 0.80 to about 1 .00, about 0.85 to about 1 .00, about 0.90 to about 1 .00, about 0.95 to about 1 .00, about 0.40 to about 0.95, about 0.40 to about 0.90, about 0.40 to about 0.85, about 0.40 to about 0.80, about 0.40 to about 0.75, about 0.40 to about 0.70, about 0.40 to about 0.65, about 0.40 to about 0.60, about 0.40 to about 0.55, about 0.40 to about 0.50, about 0.40 to about 0.45, about 0.40, about 0.45, about 0.50, about 0.55, about 0.60, about 0.65, about 0.70, about 0.75, about 0.80, about 0.85, about 0.90, about 0.95, about 1 .00, or any range or value therein.

The alloy compositions of the present disclosure may be selected from the group consisting of the following alloy compositions:

• (Nd₀.75 ro.25)i i.i-Feei.7B₆.₂Zri

• (Nd₀.75Pro.25) i i .4-Fe₈i_.4B_6.2Zr₁

· (Ndo sPro .25) 11.76^" Feel .04Β6.2ΖΠ

• ( do.75Pf₀.25)_{l 2}-Fe₈₀.8B6.₂Zr

• [(Ndo.75Pro.25)o.8Ceo.2] 1

• [( do.75PfO.25)o.₈Ce₀.₂]_l2-Fe₈o.8B6.₂Zr₁

• [( do.75PfO.25)o.₆Ce₀.4]_l2-Fe₈o.8B6.₂Zr₁ [(Ndo. 5Pfo.25)o.6Ceo.4]_l2.5"FS80.3B6.₂Zr

[(Ndo.7₅Pro.25)o.5Ce₀.₅]i₂-Fe₈o_.8B_6.2Zr₁

[(Ndo. 5Pfo.25)o.5Ceo.5]_l2.5"Fe80.3B6.₂Zr

[( do. 5Pr₀.25)o.₄Ce₀.6]_l2.5"FS80.3B6.₂Zr₁

The alloy compositions of the present disclosure may be selected from a composition the following table:

The present disclosure also provides a magnetic material comprising an alloy composition as disclosed herein. The alloy composition may be of formulas (la), (I) or (II). The present disclosure also provides a bonded magnet comprising an alloy composition or magnetic material as disclosed herein. The alloy composition may be of formulas (la), (I) or (II).

The bonded magnet may comprise a bonding agent. The bonding agent may be epoxy, polyamide, polyphenylene sulfide, a liquid crystalline polymer, or a combination thereof. The bonding agent may be epoxy.

The bonded magnet may comprise 1 .0 wt% to about 5.0 wt% bonding agent, or about 1 .5 wt% to about 5.0 wt%, or about 2.0 wt% to about 5.0 wt%, or about 2.5 wt% to about 5.0 wt%, or about 3.0 wt% to about 5.0 wt%, or about 3.5 wt% to about 5.0 wt%, or about 4.0 wt% to about 5.0 wt%, or about 4.5 wt% to about 5.0 wt%, or about 1 .5 wt% to about 5.0 wt%, or about 2.0 wt% to about 5.0 wt%, or about 2.5 wt% to about 5.0 wt%, or about 3.0 wt% to about 5.0 wt%, or about 3.5 wt% to about 5.0 wt%, or about 4.0 wt% to about 5.0 wt%, or about 4.5 wt% to about 5.0 wt%, or about 1 .0 wt%, or about 1 .5 wt%, or about 2.0 wt%, or about 2.5 wt%, or about 3.0 wt%, or about 3.5 wt%, or about 4.0 wt%, or about 4.5 wt%, or about 5.0 wt%, or any range or value therein.

The bonded magnet may comprise one or more additives or mould release agent selected from a high molecular weight multi-functional fatty acid ester, stearic acid, hydroxy stearic acid, a high molecular weight comples ester, a long chain ester of pentaerythritol, palmitic acid, a polyethylene based lubricant concentrate, an ester of montanic acid, a partly saponified ester of montanic acid, a polyolefin wax, a fatty bis-amide, a fatty acid secondary amide, a polyoctanomer with high trans content, a maleic anhydride, a glycidyl-functional acrylic hardener, zinc stearate, and a polymeric plasticizer.

The bonded magnet may comprise about 0.01 wt% to about 0.05 wt% additive or mould release agent, or about 0.01 wt% to about 0.04 wt%, or about 0.01 wt% to about 0.03 wt%, or about 0.01 wt% to about 0.02 wt%, or about 0.02 wt% to about 0.05 wt%, or about 0.03 wt% to about 0.05 wt%, or about 0.04 wt% to about 0.05 wt%, or about 0.01 wt%, or about 0.02 wt%, or about 0.03 wt%, or about 0.04 wt%, or about 0.05 wt% additive or mould release agent, or any range or value therein.

The bonded magnet may comprise, by weight, from about 1 % to about 5% epoxy, or about 1 .5% to about 5% epoxy, about 2.0% to about 5% epoxy, about 2.5% to about 5% epoxy, about 3.0% to about 5% epoxy, about 3.5% to about 5% epoxy, about 4.0% to about 5% epoxy, about 4.5% to about 5% epoxy, about 1 .0% to about 4.5% epoxy, about 1 .0% to about 4.0% epoxy, about 1 .0% to about 3.5% epoxy, about 1 .0% to about 3.0% epoxy, about 1 .0% to about 2.5% epoxy, about 1 .0% to about 2.0% epoxy, about 1 .0% to about 1 .5% epoxy, about 1 .0%, about 1 .5%, about 2.0%, about 2.5%, about 3.0%, about 3.5%, about 4.0%, about 4.5%, about 5.0%, or any range or value therein.

The bonded magnet may comprise, by weight, from about 0.01 % to about 0.05% zinc stearate. The bonded magnet may comprise, by weight, from about 0.01 %, about 0.02%, about 0.03%, about 0.04% or about 0.05% zinc stearate.

The bonded magnet may be produced through a variety of pressing/molding processes, including, but not limited to, compression molding, extrusion, injection molding, calendering, screen printing, spin casting, and slurry coating. The bonded magnet may be made, after the magnetic powders have been heat treated and mixed with the binding agent, by compression molding.

The bonded magnet may have a density of from about 5.0 to about 6.5 gm/cm³, or from about 5.2 to about 6.5 gm/cm³, or from about 5.5 to about 6.5 gm/cm³, or from about 5.8 to about 6.5 gm/cm³, or from about 6.0 to about 6.5 gm/cm³, or from about 6.2 to about 6.5 gm/cm³, or from about 5.0 to about 6.2 gm/cm³, or from about 5.0 to about 6.0 gm/cm³, or from about 5.0 to about 5.8 gm/cm³, or from about 5.0 to about 5.5 gm/cm³, or from about 5.0 to about 5.2 gm/cm³, or about 5.0 gm/cm³, about 5.2 gm/cm³, about 5.5 gm/cm³, about 5.8 gm/cm³, about 6.0 gm/cm³, about 6.2 gm/cm³, about 6.5 gm/cm³, or any range or value therein.

The bonded magnet may have a permenance coefficient ("PC") of from about 0.2 to about 12.0. from about 0.5 to about 12.0, from about 1 .0 to about 12.0, from about 1 .5 to about 12.0, from about 2.0 to about 12.0, from about 2.5 to about 12.0, from about 3.5 to about 12.0, from about 4.0 to about 12.0, from about 4.5 to about 12.0, from about 5.0 to about 12.0, from about 5.5 to about 12.0, from about 6.0 to about 12.0, from about 6.5 to about 12.0, from about 7.0 to about 12.0, from about 7.5 to about 12.0, from about 8.0 to about 12.0, from about 8.5 to about 12.0, from about 9.0 to about 12.0, from about 9.5 to about 12.0, from about 10.0 to about 12.0, from about 10.5 to about 12.0, from about 1 1 .0 to about 12.0, from about 1 1 .5 to about 12.0, from about 0.2 to about 1 1 .5, from about 0.2 to about 1 1 .0, from about 0.2 to about 10.5, from about 0.2 to about 10.0, from about 0.2 to about 9.5, from about 0.2 to about 9.0, from about 0.2 to about 8.5, from about 0.2 to about 8.0, from about 0.2 to about 7.5, from about 0.2 to about 7.0, from about 0.2 to about 6.5, from about 0.2 to about 6.0, from about 0.2 to about 5.5, from about 0.2 to about 5.0, from about 0.2 to about 4.5, from about 0.2 to about 4.0, from about 0.2 to about 3.5, from about 0.2 to about 3.0, from about 0.2 to about 2.5, from about 0.2 to about 2.0, from about 0.2 to about 1 .5, from about 0.2 to about 1 .0, from about 0.2 to about 0.5, or about 0.2, or about 0.5, or about 1 .0, or about 1 .5, or about 2.0, or about 2.5, or about 3.0, or about 3.5, or about 4.0, or about 4.5, or about 5.0, or about 5.5, or about 6.0, or about 6.5, or about 7.0, or about 7.5, or about 8.0, or about 8.5, or about 9.0, or about 9.5, or about 10.0, or about 10.5, or about 1 1 .0, or about 1 1 .5, or about 12.0, or any range or value therein.

A unique characteristic of the present invention's bonded magnet is that it exhibits reduced flux-aging loss. The bonded magnet may exhibit a flux-aging loss of less than about 4.0% when aged at 125° C for 100 hours. In some embodiments, the bonded magnet may exhibit a flux-aging loss of less than about 3.8% when aged at 125° C for 100 hours, or less than about 3.6%, or less than about 3.4%, or less than about 3.2%, or less than about 3.0%, or less than about 2.8%, or less than about 2.6%, or less than about 2.4%, or less than about 2.2%, or less than about 2.0%, or less than about 1 .8%, or less than about 1 .6%, or less than about 1 .4% when aged at 125° C for 100 hours, or any range or value therein.

A further unique characteristic of the bonded magnet is that it may exhibit a flux-aging loss of less than about 5.0% when aged at 125° C for 1000 hours. In some embodiments, the bonded magnet may exhibit a flux-aging loss of less than about 4.8% when aged at 125° C for 1000 hours, or less than about 4.6%, or less than about 4.4%, or less than about 4.2%, or less than about 4.0%, or less than about 3.8%, or less than about 3.6%, or less than about 3.4%, or less than about 3.4% when aged at 125° C for 1000 hours, or any range or value therein.

Another unique characteristic of the bonded magnets of the present disclosure are that they may exhibit an intrinsic coercivity (H_ci) of greater than about 9.0 kOe when measured at about 24°C. In some embodiments, the bonded magnet may exhibit H_ci of greater than about 9.2 kOe at about 24°C, or greater than about 9.4 kOe, or greater than about 9.6 kOe, or greater than about 9.8 kOe, or greater than about 10.0 kOe, or greater than about 10.2 kOe, or greater than about 10.4 kOe, or about 10.6 kOe, or greater than about 10.8 kOe, or greater than about 1 1 .0 kOe, or greater than about 1 1 .5 kOe, or greater than about 12.0 kOe, or greater than about 12.5 kOe, or greater than about 13.0 kOe at about 24°C. In some embodiments, the bonded magnet may exhibit H_ci of about 9.5 to about 13.0 kOe at about 24°C, or about 10.0 to about 13.0 kOe, or about 10.5 to about 13.0 kOe, or about 1 1 .0 to about 13.0 kOe, or about 1 1 .5 to about 13.0 kOe, or about 12.0 to about 13.0 kOe, or about 12.5 to about 13.0 kOe, or about 10.0 to about 12.5 kOe, or about 10.0 to about 12.0 kOe, or about 10.0 to about 1 1 .5 kOe, or about 10.0 to about 1 1 .0 kOe, or about 10.0 to about 10.5.0 kOe at about 24°C, or any range or value therein.

Advantageously, the bonded magnets of the present disclosure may exhibit high H_ci values, which remain high at elevated temperatures. The bonded magnets of the present disclosure are that they may exhibit an intrinsic coercivity (H_ci) of greater than about 6.5 kOe when measured at about 120°C. In some embodiments, the bonded magnet may exhibit H_ci of greater than about 7.0 kOe at about 120°C, or greater than about 7.5 kOe, or greater than about 8.0 kOe, or greater than about 8.5 kOe, or greater than about 9.0 kOe, or greater than about 9.5 kOe at about 120°C. In some embodiments, the bonded magnet may exhibit H_ci of about 6.5 to about 9.5 kOe at about 120°C, or about 7.0 to about 9.5 kOe, or about 7.5 to about 9.5 kOe, or about 8.0 to about 9.5 kOe, or about 8.5 to about 9.5 kOe, or about 9.0 to about 9.5 kOe, or about 6.0 to about 9.0 kOe, or about 6.0 to about 8.5 kOe, or about 6.0 to about 8.0 kOe, or about 6.0 to about 7.5 kOe, or about 6.0 to about 7.0 kOe, or about 6.0 to about 6.5 kOe at about 120°C, or any range or value therein.

The bonded magnets of the present invention advantageously exhibit a unique low β coefficient (percentage loss in H_ci per degree temperature rise). The bonded magnets of the present disclosure may exhibit a β coefficient of less than about 0.375 %/°C, or less than about 0.370 %/°C, or less than about 0.365 %/°C, or less than about 0.360 %/°C, or less than about 0.355 %/°C, or less than about 0.350 %/°C, or less than about 0.345 %/°C, or less than about 0.340 %/°C, or less than about 0.335 %/°C, or less than about 0.330 %/°C, or less than about 0.325 %/°C, or any range or value therein.

The bonded magnets of the present disclosure may exhibit high remanence (B_r) values of greater than about 5 kG at about 24°C. In some embodiments, the bonded magnet may exhibit B_r of greater than about 5.3 kG at about 24°C, or greater than about 5.6 kG, or greater than about 5.9 kG, or greater than about 6.2 kG, or greater than about 6.5 kG, or greater than about 6.5 kG, or greater than about 6.8 kG, or greater than about 7.0 kG, or greater than about 7.2 kG at about 24°C. In some embodiments, the bonded magnet may exhibit B_r of about 5 kG to about 7.2 kG at about 24°C, or about 5.3 kG to about 7.2 kG, or about 5.6 kG to about 7.2 kG, or about 5.9 kG to about 7.2 kG, or about 6.2 kG to about 7.2 kG, or about 6.5 kG to about 7.2 kG, or about 6.8 kG to about 7.2 kG, or about 7.0 kG to about 7.2 kG, or about 5.0 kG to about 7.0 kG, or about 5.0 kG to about 6.8 kG, or about 5.0 kG to about 6.5 kG, or about 5.0 kG to about 6.2 kG, or about 5.0 kG to about 5.9 kG, or about 5.0 kG to about 5.6 kG, or about 5.0 kG to about 5.3 kG, or any range or value therein.

The bonded magnets of the present disclosure may exhibit high remanence (B_r) values which remain high at high temperatures. The bonded magnets of the present disclosure may exhibit a remanence (B_r) value of greater than about 4 kG at about 120°C. In some embodiments, the bonded magnet may exhibit B_r of greater than about 4.2 kG at about 120°C, or greater than about 4.4 kG, or greater than about 4.6 kG, or greater than about 4.8 kG, or greater than about 5.0 kG, or greater than about 5.2 kG, or greater than about 5.4 kG, or greater than about 5.6 kG, or greater than about 5.8 kG, or greater than about 6.0 kG, or greater than about 6.2 kG at about 120°C. In some embodiments, the bonded magnet may exhibit B_r of about 4.0 kG to about 6.2 kG at about 120°C, or about 4.2 kG to about 6.2 kG, or about 4.4 kG to about 6.2 kG, or about 4.6 kG to about 6.2 kG, or about 4.8 kG to about 6.2 kG, or about 5.0 kG to about 6.2 kG, or about 5.2 kG to about 6.2 kG, or about 5.4 kG to about 6.2 kG, or about 5.6 kG to about 6.2 kG, or about 5.8 kG to about 6.2 kG, or about 6.0 kG to about 6.2 kG, or about 4.2 kG to about 6.0 kG, or about 4.2 kG to about 5.8 kG, or about 4.2 kG to about 5.6 kG, or about 4.2 kG to about 5.4 kG, or about 4.2 kG to about 5.2 kG, or about 4.2 kG to about 5.0 kG, or about 4.2 kG to about 5.8 kG, or about 4.2 kG to about 5.6 kG, or about 4.2 kG to about 5.4 kG, or about 4.2 kG to about 5.2 kG, or about 4.2 kG to about 5.0 kG, or about 4.2 kG to about 4.8 kG, or about 4.2 kG to about 4.6 kG, or about 4.2 kG to about 4.4 kG, or any range or value therein.

The magnetic materials disclosed herein may exhibit a near stoichiometric RE₂Fe₁₄B single-phase microstructure, as determined by X-Ray diffraction. The magnetic materials disclosed herein may comprise crystal grain sizes ranging from about 0.01 μηι to about 0.1 μηι, or about 0.02 μηι to about 0.1 μηι, or about 0.04 μηι to about 0.1 μηι, or about 0.06 μηι to about 0.1 μηι, or about 0.08 μηι to about 0.1 μηι, or about 0.01 μηι to about 0.08 μηι, or about 0.01 μηι to about 0.06 μηι, or about 0.01 μηι to about 0.04 μηι, or about 0.01 μηι to about 0.02 μηι, or about 0.01 μηι, or about 0.02 μηι, or about 0.04 μηι, or about 0.06 μηι, or about 0.08 μηι, or about 0.1 μηι, or any range or value therein.

In general, the bonded magnets of the present disclosure may be prepared by melting the rare earth metals, iron, boron and refractory metal components using arc melting or induction-melting techniques to form an alloy ingot. The resulting alloy ingot is then remelted and rapidly quenched using melt spinning or jet-caster technology. Generally, this technology involves a stream of liquid alloy being directed on to rapidly rotating metallic wheel surface (10- 50 m/s). The resulting melt-spun ribbons may be crushed into -40mesh powders and annealed at 500-700°C for a few minutes in an inert atmosphere. This powder may then be blended with 1 to 4 wt.% polymer and 0.1 wt.% mould-release agent. The resulting blend may then be compression moulded with a pressure of about 7 ton/cm². The compacts may then be cured (180°C, 1 hour) and magnetized, for use as bonded magnets.

The present invention provides a method of making a bonded magnet. The method comprises:

(i) forming a melt comprising a composition of Formula (I): RE_x-Feioo-x-y-z-B_y-M_z - Formula (I) wherein:

M is a one or more refractory metals selected from the group consisting of Zr, Nb, Mo, Ti, V, Cr, Mn, Hf, Ta and W; and x, y and z are atom% in which 10.5≤x≤14, 5.5≤y≤6.5 and 0.5≤z≤1.5, optionally wherein 0.1 atom% to 10 atom% of Fe may be substituted with cobalt; (ii) solidifying the melt, thereby obtaining a magnetic powder;

(iii) thermally annealing the magnetic powder;

(iv) mixing the magnetic powder with a binding agent; and

(v) pressing the magnetic powder and the binding agent to form the bonded magnet. The present invention additionally provides a method of making a bonded magnet, the method comprising the following steps:

(i) forming a melt comprising a composition of Formula (II): [( Pr_aNd₍i -aj) _bCei _-b]x- Fei oo-x-y-z- B_y- M_z - Formula (II) wherein:

(ii) solidifying the melt, thereby obtaining a magnetic powder; (iii) thermally annealing the magnetic powder;

(iv) mixing the magnetic powder with a binding agent; and

The present invention additionally provides a method of making a bonded magnet, comprising forming a melt comprising a disclosed alloy composition, rapidly solidifying the melt to obtain a magnetic powder; and thermally annealing the magnetic powder at a temperature range of about 500° C to about 700° C for about 10 to about 100 minutes; mixing and/or coating the magnetic powder with a binding agent; and pressing and/or molding the powders and binding agent. The various embodiments disclosed and/or discussed herein, such as the compositions of the magnetic material, rapid solidification processes, thermal annealing processes, compression processes, and magnetic properties of the magnetic material and the bonded magnet, are encompassed by the disclosed methods.

Step (iii) of the disclosed methods may be performed at a temperature of about 500°C to about 700°C, or about 550°C to about 700°C, or about 600°C to about 700°C, or about 650°C to about 700°C, or about 500°C to about 650°C, or about 500°C to about 600°C, or about 500°C to about 550°C, or any range or value therein. Step (iv) of the disclosed methods may be performed at a pressure of about 600 MPa to about 900 MPa, or about 650 MPa to about 900 MPa, or about 700 MPa to about 900 MPa, or about 750 MPa to about 900 MPa, or about 800 MPa to about 900 MPa, or about 850 MPa to about 900 MPa, or about 600 MPa to about 850 MPa, or about 600 MPa to about 800 MPa, or about 600 MPa to about 750 MPa, or about 600 MPa to about 700 MPa, or about 600 MPa to about 650 MPa, or any range or value therein.

Step (vi) of the disclosed methods may further comprise the step of curing the magnet material obtained from step (v). Step (vi) of the disclosed methods may be performed at a temperature of about 150°C to about 200°C, or about 160°C to about 200°C, or about 170°C to about 200°C, or about 180°C to about 200°C, or about 190°C to about 200°C, or about 150°C to about 190°C, or about 150°C to about 180°C, or about 150°C to about 170°C, or about 150°C to about 160°C, or any range or value therein. Step (vi) of the disclosed methods may be performed for about 10 to about 100 minutes, or about 10 to about 90 minutes, or about 10 to about 80 minutes, or about 10 to about 70 minutes, or about 10 to about 60 minutes, or about 10 to about 50 minutes, or about 10 to about 40 minutes, or about 10 to about 30 minutes, or about 10 to about 20 minutes, or about 20 to about 100 minutes, or about 10 to about 90 minutes, or about 10 to about 80 minutes, or about 10 to about 70 minutes, or about 10 to about 60 minutes, or about 10 to about 50 minutes, or about 10 to about 40 minutes, or about 10 to about 30 minutes, or about 10 to about 20 minutes, or any range or value therein. The disclosed methods may be used for making a bonded magnet disclosed herein.

The disclosed bonded magnets may be obtainable or obtained by a method disclosed herein.

Brief Description of Drawings

The accompanying drawings illustrate a disclosed embodiment and serves to explain the principles of the disclosed embodiment. It is to be understood, however, that the drawings are designed for purposes of illustration only, and not as a definition of the limits of the invention. Fig. 1

[Fig. 1 ] is a graph showing the effect of increasing levels of cerium on ageing loss in a RE- Fe-B composition of Table 3 with a fixed rare earth content when measured at 120 °C for 1000 hours. Fig. 2

[Fig. 2] is a graph showing the effect of including a refractory metal (1 at%) on ageing loss in a RE-Fe-B composition of Table 2 with a fixed rare earth content when measured at 180 °C for 1000 hours.

Fig. 3 [Fig. 3] is a graph showing the effect of increasing levels of cerium on ageing loss in a RE- Fe-B-R composition of Table 4 with a fixed rare earth content when measured at 125 °C for 1000 hours.

Fig. 4

[Fig. 4] is a series of graphs showing the correlation between ageing loss at 125 °C for 1000 hours of a composition of Table 1 and H_ci value at 24 °C and 120 °C.

Fig. 5

[Fig. 5] is a graph showing the correlation between the β coefficient (percentage loss in H_ci per degree temperature rise) and a cerium containing composition of Table 1 at a temperature from 24°C to 120°C. Fig. 6

[Fig. 6] is a series of graphs comparing the ageing loss between MQP, RE-Fe-B-Nb and RE-Fe-B-Zr of Table 5 (A: Comparison between MQP, RE-Fe-B-Nb and RE-Fe-B-Zr; B: Comparison between RE-Fe-B-Nb and RE-Fe-B-Zr). Fig. 7

[Fig. 7] is a series of graphs comparing the ageing performance of NdPr/NdPrCe-Fe-B compositions with and without a refractory metal (A: Comparison of NdPr-Fe-B compositions with and without a refractory metal; B: Comparison of NdPrCe-Fe-B compositions (with 20% Ce content) with and without a refractory metal; C: Comparison of NdPrCe-Fe-B compositions (with 30% Ce content) with and without a refractory metal; D: Comparison of NdPrCe-Fe-B compositions (with 80% Ce content) with and without a refractory metal).

Examples

Non-limiting examples of the invention and a comparative example will be further described in greater detail by reference to specific Examples, which should not be construed as in any way limiting the scope of the invention.

Example 1 - Bonded magnet

In general, a standard hydraulic press was used to make dry-blended bonded magnets. Magnetic powders were mixed with 1 .55 wt% epoxy and 0.1 wt% zinc stearate and blended for 30 minutes using a V-blender. Bonded magnets were pressed at 7 tons/cm² for all sample groups and cured at 180^°C for 30 minutes. The magnet samples were 9.75 mm in diameter, and in order to keep a BH load line value of 2, magnet heights of 6.4 mm (-2.85 gram of powder) were targeted.

Example 2 - Effect of adjusting rare earth content on H_ci

The inventors of the present invention have surprisingly found that the ageing performance of a bonded magnet is strongly correlated to its H_ci value. It was discovered that to achieve low flux ageing loss, H_ci must remain high at elevated temperature. Fig. 4 illustrates a comparison of flux ageing losses (at 125°C for 1000 hours) of various embodiments of the bonded magnets of the present invention and that of the MQP controls (see Table 1 ). The magnets have a PC of 2. As can be seen, magnets made from the alloy compositions or magnetic materials of this invention exhibit lower flux ageing losses (from approximately -3% to -4%) as compared to that of the MQP controls (approximately -5% to - 6%). Fig. 4 also shows that the ageing performance of the magnets has a linearly correlation to the H_ci value (at 24 °C and 120 °C). As can be seen, magnets with lower flux ageing losses have a higher H_ci value.

Fig. 6 illustrates a comparison of flux ageing losses (at 125°C for 1000 hours) of various embodiments of the bonded magnets of the present invention and that of MQP controls (see Table 5). Figs. 6A and 6B show the comparison between MQP controls and bonded magnets of the present invention comprising Nb or Zr as the refractory metal. The magnets have a PC of 2. As can be seen, magnets made from the alloy compositions or magnetic materials of this invention exhibit lower flux ageing losses (approximately -4% with Zr as the refractory metal, and approximately -4% to -10% with Nb as the refractory metal) as compared to that of controls (approximately -4% to -14%).

Table 5

AC05 [(Ndo.7₅ ro.25)o.5Ceo.5] l 1.76-Fe₈o.94-B₆-Nbi.3 -5.8% 50%

AC06 [(Ndo.7₅Pro.25)o.4Ce₀.6] l 1.76- e₈o.94-B₆-Nb₁.3 -6.1 % 60%

AC07 [(Ndo.7₅ ro.25)o.3Ceo.7] l 1.76-Fe₈o.94-B₆-Nbi.3 -8.0% 70%

AC08 [(Ndo.7₅Pro.25)o.2Ce₀.₈] i i .76-Fe₈o.94-B₆-Nb₁.3 -10.2% 80%

RE-Fe-B-Zr NdZr Nd₁₂-Feso.s-B6.₂-Zr_! -3.3% 0%

13-9HD3 [( d₀.75PfO.25)o.8Ce₀.₂]i2-Fe8o.8-B6.₂-Zr₁ -3.3% 20%

12-8HD3 [(Ndo.75Pfo.25)o.6Ceo.4]l2.5-Fe80.3-B6.2-Zr -3.4% 40%

Ce50HD2 [(Ndo.75Pfo.25)o.5Ceo.5] I 2.5-Fe30.3-B6.2-Zr! -3.2% 50%

Ce60HD2 [(Ndo.75Pfo.25)o.4Ceo.6] I 2.5-Fe30.3-B6.2-Zr! -4.7% 60%

Fig. 4 illustrates the relationship between flux ageing loss (at 125°C for 1000 hours) and H_ci values (at 24 °C and 120 °C). As can be seen, ageing performance of the magnets has a linearly correlation to the H_ci value and magnets with lower flux ageing losses have a higher H_ci value.

The bonded magnets of the present invention advantageously exhibit a unique low β coefficient (percentage loss in H_ci per degree temperature rise). A low β coefficient indicates that the H_ci value is retained at elevated temperatures and therefore contributes to improved ageing performance. Fig. 5 illustrates the β coefficient (% / °C) (between 24°C to 120°C) of some of the magnets of the present invention in relation to the cerium content (see Table 1 ). As can be seen, the cerium containing magnets of the present invention (up to 60% cerium) retain high H_ci values at elevated temperatures and therefore contributes to improved ageing performance.

Example 3 - Effect of adjusting rare earth content

The inventors of the present invention have surprisingly and advantageously found that by adjusting the rare earth content to raise H_ci, the thermal stability and ageing performance of the disclosed compositions show significant improvement and are further cheaper to produce.

Further, although cerium is a lower cost and more abundant rare earth element, it is known that including cerium in permanent magnets leads to poor thermal stability (see Comparative Example 1 ). However, the inventors have surprisingly and advantageously found that including cerium in the rare earth content of a magnet may not only improve ageing performance, but leads to substantial cost savings as well.

Table 1 below shows the properties and ageing performance of embodiments of the bonded magnets of the present invention compared with bonded magnet MQP-14-12.

MQP-14-12 is a composition containing 1 1 .76 at% Nd (Ndn.76-Fe₈o.94-B₆-Nbi.₃). MQP-14- 12 has an H_ci value of 12.22 kOe at 24 °C (H_ci(24°_C)) and 8.43 kOe at 120 °C (H_{ci (120}°_C))- MQP-14- 12 shows an ageing loss of -3.7% at 125°C at 1000 hours (hereon referred to as

The raw material cost of producing MQP-14-12 is US$14.44 (as of October 2015).

An embodiment of the present invention is 15-9HD5 ((PrNd)₁₂-Fe₈o.8-B6.2-Zr₁). When the rare earth content is 12 at.% (PrNd), a high H_{ci (24}=Q value of 12.02 kOe and H_{ci (120°}o of 7.75 kOe is achieved. 15-9HD5 displays an improved

of -3.4% over the of MQP-14- 12 which is -3.7%. Moreover, as a result of adjusting the rare earth content, the raw material cost of 15-9HD5 is only US$12.22. 15-9HD5 is therefore a cheaper and improved alternative to MQP-14-12 which has a raw material cost of US$14.44 (as of October 2015).

Another embodiment of the present invention is 13-9HD3 ((PrNd₈Ce₂)i₂-Fe₈o.8-B_6.2-Zr₁) which contains 20% cerium in its rare earth content. When the rare earth content is (PrNd₈Ce₂)i₂, a high H_{ci (2 °}o value of 1 1 .27 kOe is achieved and H_{ci (}I₂O°Q of 7.45 kOe. 13-9HD3 displays an improved

of -3.3% over the of MQP-14-12 which is -3.7%. This is a surprising result because, as mentioned above and evidenced in Comparative Example 1 , generally, including cerium as part of the rare earth metal content in a magnet leads to poor ageing performance, with the ageing performance worsening with increasing cerium content. However, the compositions of the present invention may show improved ageing performance over non-cerium containing compositions. Additionally, as a result of adjusting the rare earth content to include the cheaper and more abundant cerium, the raw material cost may be significantly reduced. In the present example, the raw material cost of 13-9HD3 is only US$10.79 (as of October 2015), a significant savings when compared to MQP-14-12 which has a raw material cost of US$14.44 (as of October 2015). Further surprisingly and advantageously, when the rare earth content includes 50% cerium (Ce50HD2: (PrNd₅Ce₅)i_2.5-Fe-B_6.2-Zr₁), an improved

of -3.2% at is observed when compared to MQP-14-12

= -3.7%). Additionally, as a result of adjusting the rare earth content to include the cheaper and more abundant cerium, the raw material cost is significantly reduced. In the present example, the raw material cost of 13-9HD3 is only US$7.91 (as of October 2015), a significant savings when compared to MQP-14-12 which has a raw material cost of US$14.44 (as of October 2015). Further, Ce60HD2 of the present invention ((PrNd₄Ce₆)i2_.5- e₈o_.3-B_6.2-Zr₁) has 60% cerium in its rare earth content and has a high H_{ci (24}°ο of 9.99 kOe and H_{ci (12}o°o of 6.79 kOe. Ce60HD2 further displays a good ageing performance A₁₂₅°c/ioooh of -4.7%. Moreover, the raw material cost of Ce60HD2 is only US$6.85 (as of October 2015), which is less than half of MQP- 14-12 at US$14.44 (as of October 2015).

Therefore, the above results evidence that adjusting the rare earth content of a bonded magent surprisingly increases H_ci which remains high at elevated temperatures. The bonded magnets of the present invention not only advantageously lead to improved ageing performance, but also to substantial cost savings. The above results also surprisingly and advantageously evidence that including cerium in the rare earth content, contrary to existing evidence (see Comparative Examples 1 and 2), may advantageously lead to improved ageing performance and substantial cost savings.

Example 4 - Effect of the inclusion of refractory metal (R) The inventors of the present invention have further surprisingly and advantageously found that adding a refractory metal (R) to a RE-Fe-B composition achieves high H_ci and leads to improved ageing performance.

Table 2 below shows the effect on adding a refractory metal to a Nd_11.5-Fe₈₂.g-B_5.6 composition (HTO60) which has a H_ci value of 10.6 kOe and an ageing loss of -34.9% at 180 C for 1000 hours (hereon referred to as A₍₁₅₀°c/ioooh)) - The results of the table are shown in Fig. 3.

Table 2

PC2

ΪΓ U U:

magnets

Aqsnq @

Composition {§!¾¾) AHoy ID

180C Br ϋά (BH)max ¾¾ 1000-hr ifeO) <K¾9 iMSQe) i%)

Nd i.s-Fe82.8-Bs.» HT06D -34.9% 9.08 1 0 6 17.1 82.9

Ud i ,5-Fes ! .s-Ti 1.8 -Bs.s HT055 -23.4% 8.91 1 0.7 16.7 84.2

U611.5- Fes ! .s -V i .o- Bs. s HT056 -19.6% 8.86 1 0.6 16.3 83.2

Ndi 1.s-Fes s-Cn .o- Bs.s HT057 -17.1 % 8.76 1 0.3 15.8 82.5

Ndi i.5-Fesi.s-Zri.o- Bs.s HT058 -28.0^'% 8.99 1 0.5 Ί 7 1 84.6 di 1.5-Fes !.S-MQ-- .o- Bs. ΗΪ059 -15.3% 8.50 1 3.0 1 5.1 83.5

Ndi 1.s-Fes2.i-M0ii.5- B».« ΗΪΌ62 -24.2% 8.83 1 1 7 18.3 83.8

Nd 1.s-Feei 3- i .a- 8s.s HTQGQ - 9.4% 8,85 1 1 9 16.5 84.Θ

As shown in Table 2 and Fig. 2, A_(150°c_/iooo_h) of HTO60 -34.9%. Advantageously and surprisingly, adding small amounts of refractory metal such as Ti, V, Cr, Zr, Mo or Nb, dramatically improves the ageing performance of a Nd-Fe-B composition. Adding 1 at% of Ti (HT055: Ndn.5Fe₈i.9T .0B56) shows an improved ageing performance at -23.4% under the same conditions. Adding 1 at% of V (HT056: Nd .5Fe₈i.9V1.0B5 6) shows an improved ageing performance at -19.6% under the same conditions. Adding 1 at% of Cr (HT057: Ndn.5Fe₈i.9Cr1.0B5 6) shows an improved ageing performance at -1 7.1 % under the same conditions. Adding 1 at% of Zr (HT058: Ndn.5Fe₈i.9Zr1.0B56) shows an improved ageing performance at -28.0% under the same conditions. Adding 1 at% of Mo (HT059: Ndn.5Fe₈i.9Mo1.0B5 6) shows an improved ageing performance at -1 5.3% under the same conditions. Adding 0.5 at% of Mo (HT062: Ndn.5Fe₈₂.4Moo.5B5 6) shows an improved ageing performance at -24.2% under the same conditions. Adding 1 at% of Nb (HTO66: Ndn.5Fe₈i.9Nb1.0B5 6) shows an improved ageing performance at -1 9.4% under the same conditions.

Fig. 7 is a series of graphs illustrating the ageing performance advantage of including a refractory metal in a bonded magnet (PC = 2) . As can be seen in Fig. 7A, a bonded magnet containing 1 at% Zr exhibits lower flux ageing loss at 1 50°C over the course of 1 hour to 1000 hours (approximately -8%) as compared to that of bonded magnets without Zr (approximately - 1 0% to -13%). As can be seen in Fig. 7B, a bonded magnet containing 1 at% Zr exhibits lower flyx ageing loss at 1 20°C over the course of 1 hour to 1 000 hours (approximately -5%) as compared to that of bonded magnets without Zr (approximately -5.5%). As can be seen in Fig. 7C, a bonded magnet containing 1 at% Zr exhibits lower flux ageing loss at 1 20°C over the course of 1 hour to l OOOhours (approximately -4.25%) as compared to that of bonded magnets without Zr (approximately -4.6%). As can be seen in Fig. 7D, a bonded magnet containing 1 at% Zr exhibits lower flux ageing loss at 120°C over the course of 1 hour to 1000 hours (approximately -1 1 %) as compared to that of bonded magnets without Zr (approximately -14%). As can be seen from Figs. 7A to 7D, there is a clear ageing performance advantage in including a refractory metal in a bonded magnet.

Therefore, these results evidence that adding a refractory metal to a RE-F-B composition leads to improved ageing performance.

The present invention has been explained generally, and also by reference to the preceding examples which describe in detail the preparation of the magnetic powders and the bonded magnets of the present invention. The examples also demonstrate the superior and unexpected properties of the magnets and magnetic powders of the present invention. The preceding examples are illustrative only and in no way limit the scope of the present invention. It will be apparent to those skilled in the art that many modifications, both to products and methods, may be practiced without departing from the purpose and scope of this invention.

Comparative Example

Comparative Example 1

Cerium (Ce) is a more abundant and lower-cost rare earth metal. However, known bonded magnets comprising Ce suffer from reduced thermal stability and increased flux ageing loss. These known associated problems with using Ce in such magnets have led to magnet producers having concerns about selecting cerium-containing materials because of the risk of lower ageing performance.

As shown in Fig. 1 and Table 3, the inclusion of cerium in a RE-Fe-B composition results in poor ageing performance, with the increasing content of cerium leading to worsening ageing performance.

Table 3 below shows the effects of adding increasing amounts of cerium to a (Ndo.7₅Pro.25) i i .65-Fe₈2.75-B_5.6 composition (CeOO) which has a H_ci value of 10.8 kOe and an ageing loss of -4.1 % at 120 °C for 1000 hours (hereon referred to as A₍₁₂o°c/ioooh)) - The results of the table are shown in Fig. 1 . H_ci was measured at room temperature (24°C).

Table 3

PC2 fvlagrssis Powders

Composition <at%) ASoy !D Aging @ 120C Br Hci Sqr. Curie

1000-hr (¾G) (tide) (SiGOe) (%} (deg.C) ί f¾_. ;_ί P Vi _fi.-Fe ;.-8_{5 e} CeOO -4.1 % 8.98 10.8 17.0 34.48 3! ! iiNd_{a ¾} rc,_¾}_ss-Ce_{c .},]„ -Fe -Bs Ce10 -4.5% 8 81 9.9 164 84 32 297

[{Md_3J5Pf_C25)_B.s-Ce_&2]_{I L55}-Fe₂,₇₅-B_ii Ce20 -4.3% 8.5S S.4 15.3 82.73 284

[(Nd_37sPi_e )_{¾ ?}-Ce¾2->] i _.si-Fes ₇₅- 8_{S ε} C«23 -4.6% 8.55 9.2 15.0 82.41 281

[<Nd_s vPrtxh -Ce i -Fes ₇₅-B_5.s Ce30 -4.7% 8.36 8.8 14 80.84 270

Ce35 -5.3% 8.28 8.0 1 7 80 42 263

Ce40 -5.6% 8.13 7.6 13.1 79.26 257

[i Nd_s }s_.s-Ce₅ j], , -Fs₅₂ -B_{5 s} Ce50 -5.8% 7.39 6.S 12.0 77.09 234

CeOO has 0% cerium content and exhibits ageing loss A₍₁₂o°c/ioooh) of -4.1 %. When 10% of cerium is added to the rare earth content (Ce10: [(Ndo.75Pro.25)o.9-Ceo.i] .65-Fe82.75-B₅.6) , the ageing loss worsens to -4.5%. When 50% of cerium is added to the rare earth content (Ce50: [(Ndo.75Pro.25)o.5-Ceo.₅]i i .65-Fe₈₂.75-B₅.₆), the ageing loss worsens to -5.8%. Therefore, the results of Fig. 1 and Table 3 evidences that, generally, including cerium as part of the rare earth metal content in a magnet leads to poor ageing performance, with the ageing performance worsening with increasing cerium content.

However, as evidenced in the examples above, the inventors of the present invention have surprisingly found that the bonded magnets of the present invention may comprise cerium while still maintaining good thermal stability, low flux ageing loss and high H_ci when measured at high temperatures. The cerium-containing bonded magnets of the present invention have the further advantage of being significantly cheaper to produce.

Comparative Example 2 As shown in Example 3 above, adding a small amount of refractory metal (R) to a RE-F-

B composition leads to improved ageing performance. However, as shown in Fig. 3 and Table 4 below, generally, the inclusion of cerium in a RE-Fe-B-R composition also results in poor ageing performance, with the increasing content of cerium leading to worsening ageing performance.

Table 4 below shows the effects of adding increasing amounts of cerium to a (PrNd)n.₇6- Fe₈o.94-B₆-Nbi.3 composition (MQP-14-13) which has a H_ci value of 12.5 kOe and an ageing loss of -3.8% at 125 °C for 1000 hours (hereon referred to as A °c/ioooh)) - The results of the table are shown in Fig. 2. H_ci was measured at room temperature (24°C).

Table 4

PC2 Magnets Powders

Compositions {ai.%} Alloy SD Aging @ 125degC Br Hci (BH)max Sqr. Curie

10C0- r {KG) (kOe) ■ MGOe) (%) (deg.C) d _t.7e- Fe_M._w-B₆-Nt>i MQP-14-12 -3.7% 8.69 12.3 15.8 83.B 305

(Ndo 11 -Fe -Bs-Nt MQP-14-13 -3.8% 8.57 12.5 15.6 84.8 298

¾ dc..7_SPr,}_.j_£}e_.sC€_C...:3i 7i:-Fe5 -B₅- 3 AC01 -3,7% 8.38 12.1 14.8 84,4 284

AC02 -3.6% 8.18 11.5 13.9 83,4 273 (fs! o-_sPr jCeo ₃ju -₆-Ρβ_δο -Ββ-Ν ] ₃ AC03 -5.0% 8.04 0.0 13.3 82,4 257

7sPr» .sCer.4η.ττΡ·&.9ΐ8νΜ>ι AC04 -5.1% 7.78 9.3 12.3 81.4 241

[<Nd57sP¾2s)e.sCe5 sjit Ts-FeacM-Bs-Nbi · AC05 -5.8% 7.55 8,6 1 .6 81.1 227 (Nds TsPr.jis j Cesii-i( .^•.-Fe.,. --₎-B.:- b:^■, AC06 -6.1% 7.19 8,2 10.4 80,7 2G9

[{Nd_{s ?}Ce_{s 7}] 11 ,-_fFs ...- .-Β.,- ό: ;. AC07 -8.0% 6.87 6.8 S 7 73,5 191

[{Ndc.75Pr5.2i J 2Ce_C..s]l 1 -Ps -B AGOE -10,2% 6.41 6.1 7.2 69.7 70 As shown in Fig. 3, the RE-Fe-B-R composition MQP-14-13 has 0% cerium content and exhibits and ageing loss A °c/ioooh) of -3.8%. When 30% of cerium is added to the rare earth content (AC03: (PrNd₇Ce₃) i i .6-Fe₈i .i-B₆Nbi.₃), the ageing loss worsens to -5.0%. When 80% of cerium is added to the rare earth content (AC08: (PrNd₂Ce₈)_11.6-Fe_81.1-B₆Nb_1.3), the ageing loss worsens to -10.2%. Therefore, the results of Fig. 3 and Table 4 evidences that, generally, including cerium as part of the rare earth metal content, even with the inclusion of a refractory metal, in a magnet leads to poor ageing performance, with the ageing performance worsening with increasing cerium content.

However, as evidenced in the examples above, the inventors of the present invention have surprisingly found that the bonded magnets of the present invention may comprise cerium while still maintaining good thermal stability, low flux ageing loss and high H_ci when measured at high temperatures. The cerium-containing bonded magnets of the present invention have the further advantage of being significantly cheaper to produce. Industrial Applicability

The disclosed bonded magnets and bonded magnets comprising the disclosed alloy compositions or magnetic materials may advantageously exhibit improved thermal stability, for e.g. low β coefficients. Advantageously, the disclosed bonded magnets may exhibit high intrinsic coercivity (H_ci) values even when measured at high temperatures, for example, temperatures higher than 100 °C.

Advantageously, the disclosed bonded magnets may exhibit low flux ageing loss. This advantageously allows the disclosed bonded magnets to exhibit good resistance to demagnetization at elevated temperatures which allows for their use in high temperature environments.

Further advantageously, the disclosed bonded magnets may comprise cerium while still maintaining good thermal stability, low flux ageing loss and high H_ci when measured at high temperatures. Also advantageously, the disclosed alloy compositions may be produced with low cost.

It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.

Claims

1 . An alloy composition of Formula (I):

RE_x-Feioo-x-y-z-B_y-M_z -- Formula (I) wherein: RE is two or more rare earth metals selected from the group consisting of La, Ce,

Pr, Nd, Y, Gd, Tb, Dy, Ho, and Yb;

M is a one or more refractory metals selected from the group consisting of Zr, Nb, Mo, Ti, V, Cr, Mn, Hf, Ta and W; x, y and z are atom% in which 10.5≤x<14, 5.5≤y≤6.5 and 0.5≤z≤1.5, optionally wherein 0.1 atom% to 10 atom% of Fe may be substituted with cobalt.

2. The alloy composition of claim 1 , wherein RE is at least two rare earth metals, wherein one of the rare earth metals is Nd.

3. The alloy composition of any one of claims 1 or 2, wherein RE is at least two rare earth metals selected from the group consisting of Pr, Nd or Ce.

The alloy composition of any one of claims 1 to 3, wherein the composition is of Formula (II):

[(Pr_aNd₍i-_a))_bCei-_b]_x-Feioo-x-y-z-B_y-M_z -- Formula (II) wherein:

5. The alloy composition of any one of claims 1 to 4, wherein M is one or more refractory metals selected from the group consisting of Zr, Nb, Ti, and Cr.

6. The alloy composition of any one of claims 1 to 5, wherein 1 1.0≤x≤12.5.

7. The alloy composition of any one of claims 1 to 6, wherein 6.0≤y≤6.5

8. The alloy composition of any one of claims 1 to 7, wherein 0.8≤z≤1.2.

9. The alloy composition of any one of claims 1 to 8, wherein 11.0≤x≤12.5, 6.0≤y≤6.5 and 0.8≤z≤1.2.

10. The alloy composition of any one of claims 1 to 9, wherein a is 0.20≤a≤0.50.

1 1 . The alloy composition of any one of claims 1 to 10, wherein b is 0.40<b≤1 .00.

12. The alloy composition of any one of claims 1 to 1 1 , wherein a is an integer of 0.20≤a≤0.50, and b is 0.40<b≤1 .00.

13. The alloy composition of any one of claims 1 to 12, wherein a is 0.20≤a≤0.30.

14. The alloy composition of any one of claims 1 to 13, wherein b is 0.40<b≤0.80.

15. The alloy composition of any one of claims 1 to 14, wherein a is 0.20≤a≤0.30, and b is 0.40≤b≤0.80.

16. The alloy composition of any one of claims 1 to 15, wherein the alloy composition is selected from the group consisting of the following alloy compositions:

• (Nd₀.75 ro.25)i i.i-Feei.7B₆.₂Zri

• (Ndo. 5P^r ₀.25)_{l 1}. 6"Fe₈₁.04B6.₂Zri

• [(Ndo.75P^r0.25)o.8Ceo.2] 11.76^" FSsi 04Β6.2ΖΓΙ

• [( do.75Pfo.25)o.₈Ceo.₂]_l2-Fe₈₀.8B6.₂Zr

· [(Nd₀.75Pro.25)o.₆Ceo.4]i₂-Fe₈o.8B₆.₂Zr₁

• [( do.75Pfo.25)o.₆Ceo.4]_l2.5"Fe₈₀.3B6.₂Zr

• [(Nd₀.75Pro.25)o.5Ceo.5]i₂-Fe₈o.8B₆.₂Zr₁

• [( do.75Pr₀.25)o.5Ceo.5]_l2.5"Fe₈o.3B6.₂Zr₁

• [( do.75Pfo.25)o.₄Ceo.6]_l2.5"Fe₈₀.3B6.₂Zr 17. The alloy composition of any one of claims 1 to 16, wherein said composition contains no cobalt.

18. A magnetic material comprising the alloy composition of any one of claims 1 to 17.

19. The magnetic material of claim 18, wherein the magnetic material exhibits an intrinsic coercivity (H_ci) value of greater than about 9.5 kOe at about 24°C. The magnetic material of any one of claims 18 or 19, wherein the magnetic material exhibits an intrinsic coercivity (H_ci) value of about 9.5 kOe to about 13.0 kOe at about 24 °C.

The magnetic material of claim 18, wherein the magnetic material exhibits an intrinsic coercivity (H_ci) value of greater than about 6.5 kOe at about 120°C.

The magnetic material of any one of claims 18 or 19, wherein the magnetic material exhibits an intrinsic coercivity (H_ci) value of about 6.5 kOe to about 9.5 kOe at about 120 °C.

The magnetic material of any one of claims 18 to 22, wherein the magnetic material exhibits a remanence (B_r) value of greater than about 5 kG at about 24°C.

The magnetic material of any one of claims 18 to 23, wherein the magnetic material exhibits a remanence (B_r) value of about 5 kG to about 7.2 kG at about 24°C.

The magnetic material of any one of claims 18 to 24, wherein the magnetic material exhibits a flux-ageing loss of less than about 4% when aged at about 120°C for about 1000 hours.

The magnetic material of any one of claims 18 to 25, wherein the magnetic material comprises equiaxed RE₂Fei₄B grains.

The magnetic material of any one of claims 18 to 26, wherein the magnetic material comprises crystal grain sizes ranging from about 0.01 pm to about 0.1 pm.

28. A bonded magnet comprising the alloy composition of any one of claims 1 to 17.

29. The bonded magnet of claim 28, wherein the bonded magnet exhibits an intrinsic coercivity (H_ci) value of greater than about 9.5 kOe at about 24°C.

30. The bonded magnet of any one of claims 28 or 29, wherein the bonded magnet exhibits an intrinsic coercivity (H_ci) value of about 9.5 kOe to about 13.0 kOe at about 24°C.

31 . The bonded magnet of claim 28, wherein the bonded magnet exhibits an intrinsic coercivity (H_ci) value of greater than about 6.5 kOe at about 120°C.

32. The bonded magnet of any one of claims 28 to 31 , wherein the bonded magnet exhibits an intrinsic coercivity (H_ci) value of about 6.5 kOe to about 9.5 kOe at about 120°C.

33. The bonded magnet of any one of claims 28 to 32, wherein the bonded magnet exhibits a remanence (B_r) value of greater than about 5 kG at about 24°C.

34. The bonded magnet of any one of claims 28 to 33, wherein the bonded magnet exhibits a remanence (B_r) value of about 5 kG to about 7.2 kG at about 24°C.

35. The bonded magnet of any one of claims 28 to 34, wherein the bonded magnet exhibits a flux-ageing loss of less than about 4% when aged at about 120°C for about 1000 hours. The bonded magnet of any one of claims 28 to 35, wherein the bonded magnet further comprises a binding agent selected from the group consisting of an organic binder, epoxy, polyamide, polyphenylene sulfide, a liquid crystalline polymer, or combinations thereof.

The bonded magnet of any one of claims 28 to 36, wherein the bonded magnet has a permeance coefficient (P_c) of from about 0.2 to about 12.0.

The bonded magnet of any one of claims 28 to 37, wherein the bonded magnet has a permeance coefficient (P_c) of about 2.0.

A method of making a bonded magnet, the method comprising the following steps:

(i) forming a melt comprising a composition of Formula (I):

RE_x-Feioo-x-y-z-B_y-M_z -- Formula (I) wherein:

RE is two or more rare earth metals selected from the group consisting of La, Ce, Pr, Nd, Y, Sm, Gd, Tb, Dy, Ho and Yb;

(ii) solidifying the melt, thereby obtaining a magnetic powder;

(iii) thermally annealing the magnetic powder;

(iv) mixing the magnetic powder with a binding agent; and (v) pressing the magnetic powder and the binding agent to form the bonded magnet.

40. A method of making a bonded magnet, the method comprising the following steps:

(i) forming a melt comprising a composition of Formula (II):

[(Pr_aNd₍i-_a))_bCei-_b]_x-Feioo-x-y-z-B_y-M_z -- Formula (II) wherein:

M is a one or more refractory metals selected from the group consisting of Zr, Nb, Mo, Ti, V, Cr, Mn, Hf, Ta and W; a and b are 0.20≤a≤0.50 and 0.40<b≤1 .00; and x, y and z are atom% in which 10.5≤X≤14, 5.5≤y≤6.5 and 0.5≤z≤1.5, optionally wherein 0.1 atom% to 10 atom% of Fe may be substituted with cobalt;

(ii) solidifying the melt, thereby obtaining a magnetic powder;

(iii) thermally annealing the magnetic powder;

(iv) mixing the magnetic powder with a binding agent; and

41 . A method of making a bonded magnet, the method comprising the following steps:

(i) forming a melt comprising a composition of any one of claims 1 to 17;

(ii) solidifying the melt, thereby obtaining a magnetic powder;

(iii) thermally annealing the magnetic powder;

42. The method of any one of claims 39 to 41 , wherein step (iii) is performed at a temperature of about 500°C to about 700°C.

43. The method of any one of claims 39 to 42, wherein step (iv) is performed at a pressure of about 600 MPa to about 900 MPa.

44. The method of any one of claims 39 to 43, further comprising step (vi) curing the magnet material obtained from step (v).

45. The method of claim 44, wherein step (vi) is performed at a temperature of about 150°C to about 200°C for about 10 to about 100 minutes.

46. The method of any one of claims 39 to 45, wherein the binding agent is selected from the group consisting of epoxy, polyamide, polyphenylene sulfide, a liquid crystalline polymer, or combinations thereof.

47. The method according to any one of claims 39 to 46 for making a bonded magnet according to any one of claims 27 to 37.

48. The method of any one of claims 39 to 47, wherein the composition of Formula (I) or

Formula (II) contains no cobalt.

49. A bonded magnet obtainable by a method according to any one of claims 39 to 48.