Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
  • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
  • H01F1/047—Alloys characterised by their composition
  • H01F1/053—Alloys characterised by their composition containing rare earth metals
  • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
  • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
  • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
  • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
  • H01F1/0578—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together bonded together
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
  • H01F41/0266—Moulding; Pressing

Definitions

• 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.
• 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.
• T c Curie temperature
• B r reversible temperature coefficient of remanence
• H ci temperature coefficient of intrinsic coercivity
• 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.
• 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.
• known Nd- Fe magnets comprising Ce suffer from reduced thermal stability and increased flux ageing loss.
• 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.
• 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
• 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.
• an alloy composition wherein the composition is of Formula (II):
• 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.
• a magnetic material comprising the alloy composition as disclosed herein.
• a bonded magnet comprising the alloy composition or magnetic material as disclosed herein.
• the disclosed bonded magnets may exhibit improved thermal stability.
• 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.
• 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.
• the disclosed alloy compositions may be produced with low cost.
• a method of making a bonded magnet comprising the following steps:
• 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;
• a method of making a bonded magnet comprising the following steps:
• 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;
• a method of making a bonded magnet comprising the following steps:
• a bonded magnet obtainable or obtained by a method as disclosed herein.
• 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.
• rare earth metal 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).
• refractory metal 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 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.
• 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.
• 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.
• 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 ⁇ coefficient (percentage loss in H ci per degree temperature rise).
• a low ⁇ 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.
• 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 ⁇ 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.
• 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 ⁇ coefficients which mean that H ci value is retained at elevated temperatures and therefore contribute to improved ageing performance.
• 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 ⁇ coefficients which mean that H ci value is retained at elevated temperatures and therefore contribute to improved ageing performance.
• 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
• 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 -Fe 10 o-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.
• 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.
• 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.
• 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 1
• 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 .0 to about 1 .2, or about 1 .1 to about 1 .2, or about
• about 0.1 atom% to about 10 atom% of iron may be substituted with cobalt.
• the composition may contain no cobalt.
• 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):
• 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.
• 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,
• alloy compositions of the present disclosure may be selected from the group consisting of the following alloy compositions:
• 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
• 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.
• 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, palm
• 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 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/cm 3 , or from about 5.2 to about 6.5 gm/cm 3 , or from about 5.5 to about 6.5 gm/cm 3 , or from about 5.8 to about 6.5 gm/cm 3 , or from about 6.0 to about 6.5 gm/cm 3 , or from about 6.2 to about 6.5 gm/cm 3 , or from about 5.0 to about 6.2 gm/cm 3 , or from about 5.0 to about 6.0 gm/cm 3 , or from about 5.0 to about 5.8 gm/cm 3 , or from about 5.0 to about 5.5 gm/cm 3 , or from about 5.0 to about 5.2 gm/cm 3 , or about 5.0 gm/cm 3 , about 5.2 gm/cm 3 , about 5.5 gm/cm 3 , about 5.8 gm/cm 3
• 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,
• 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.
• 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.
• 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.
• the bonded magnets of the present disclosure may exhibit an intrinsic coercivity (H ci ) of greater than about 9.0 kOe when measured at about 24°C.
• 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.
• 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.
• 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.
• 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.
• 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 ⁇ coefficient (percentage loss in H ci per degree temperature rise).
• the bonded magnets of the present disclosure may exhibit a ⁇ 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.
• 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.
• 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.
• 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.
• 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
• the magnetic materials disclosed herein may exhibit a near stoichiometric RE 2 Fe 14 B single-phase microstructure, as determined by X-Ray diffraction.
• the magnetic materials disclosed herein may comprise crystal grain sizes ranging from about 0.01 ⁇ to about 0.1 ⁇ , or about 0.02 ⁇ to about 0.1 ⁇ , or about 0.04 ⁇ to about 0.1 ⁇ , or about 0.06 ⁇ to about 0.1 ⁇ , or about 0.08 ⁇ to about 0.1 ⁇ , or about 0.01 ⁇ to about 0.08 ⁇ , or about 0.01 ⁇ to about 0.06 ⁇ , or about 0.01 ⁇ to about 0.04 ⁇ , or about 0.01 ⁇ to about 0.02 ⁇ , or about 0.01 ⁇ , or about 0.02 ⁇ , or about 0.04 ⁇ , or about 0.06 ⁇ , or about 0.08 ⁇ , or about 0.1 ⁇ , or any range or value therein.
• 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.
• melt spinning or jet-caster 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/cm 2 .
• 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:
• 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;
• the present invention additionally provides a method of making a bonded magnet, the method comprising the following steps:
• 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;
• 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.
• 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.
• 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.
• 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 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 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 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 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 is a graph showing the correlation between the ⁇ 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 is a graph showing the correlation between the ⁇ 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 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 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 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
• 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).
• 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.
• 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/cm 2 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.
• 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.
• 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.
• 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%).
• Ce50HD2 [(Ndo.75Pfo.25)o.5Ceo.5] I 2.5-Fe30.3-B6.2-Zr! -3.2% 50%
• 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 ⁇ coefficient (percentage loss in H ci per degree temperature rise).
• a low ⁇ coefficient indicates that the H ci value is retained at elevated temperatures and therefore contributes to improved ageing performance.
• Fig. 5 illustrates the ⁇ 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 ).
• 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.
• 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.
• cerium is a lower cost and more abundant rare earth element
• 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 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-Fe 8 o.94-B 6 -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 -Fe 8 o.8-B6.2-Zr 1 ).
• the rare earth content is 12 at.% (PrNd)
• 15-9HD5 displays an improved of -3.4% over the of MQP-14- 12 which is -3.7%.
• 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 ((PrNd 8 Ce 2 )i 2 -Fe 8 o.8-B 6.2 -Zr 1 ) which contains 20% cerium in its rare earth content.
• the rare earth content is (PrNd 8 Ce 2 )i 2
• a high H ci (2 ° o value of 1 1 .27 kOe is achieved and H ci ( I 2 O°Q of 7.45 kOe.
• 13-9HD3 displays an improved of -3.3% over the of MQP-14-12 which is -3.7%.
• the raw material cost is significantly reduced.
• 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).
• Ce60HD2 of the present invention ((PrNd 4 Ce 6 )i2 .5 - e 8 o .3 -B 6.2 -Zr 1 ) has 60% cerium in its rare earth content and has a high H ci (24 ° ⁇ of 9.99 kOe and H ci (12 o°o of 6.79 kOe. Ce60HD2 further displays a good ageing performance A 125 °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).
• the bonded magnets of the present invention not only advantageously lead to improved ageing performance, but also to 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 shows the effect on adding a refractory metal to a Nd 11.5 -Fe 82 .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)) -
• HTO60 Nd 11.5 -Fe 82 .g-B 5.6 composition
• 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 shows an improved ageing performance at -23.4% under the same conditions.
• Adding 1 at% of V shows an improved ageing performance at -19.6% under the same conditions.
• Adding 1 at% of Cr shows an improved ageing performance at -1 7.1 % under the same conditions.
• Adding 1 at% of Zr shows an improved ageing performance at -28.0% under the same conditions.
• Adding 1 at% of Mo shows an improved ageing performance at -1 5.3% under the same conditions.
• Adding 0.5 at% of Mo shows an improved ageing performance at -24.2% under the same conditions.
• Adding 1 at% of Nb shows an improved ageing performance at -1 9.4% under the same conditions.
• 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%).
• 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%).
• 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 (appro
• 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%).
• 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%).
• 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%).
• Figs. 7A to 7D there is a clear ageing performance advantage in including a refractory metal in a bonded magnet.
• Cerium (Ce) is a more abundant and lower-cost rare earth metal.
• 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.
• Table 3 shows the effects of adding increasing amounts of cerium to a (Ndo.7 5 Pro.25) i i .65-Fe 8 2.75-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 (12 o°c/ioooh)) -
• the results of the table are shown in Fig. 1 .
• H ci was measured at room temperature (24°C).
• CeOO has 0% cerium content and exhibits ageing loss A (12 o°c/ioooh) of -4.1 %.
• 10% of cerium is added to the rare earth content (Ce10: [(Ndo.75Pro.25)o.9-Ceo.i] .65-Fe82.75-B 5 .6)
• the ageing loss worsens to -4.5%.
• 50% of cerium is added to the rare earth content (Ce50: [(Ndo.75Pro.25)o.5-Ceo. 5 ]i i .65-Fe 82 .75-B 5 . 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.
• 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.
• Table 4 shows the effects of adding increasing amounts of cerium to a (PrNd)n. 7 6- Fe 8 o.94-B 6 -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)) -
• H ci was measured at room temperature (24°C).
• the RE-Fe-B-R composition MQP-14-13 has 0% cerium content and exhibits and ageing loss A °c/ioooh) of -3.8%.
• the ageing loss worsens to -5.0%.
• 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.
• 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 ⁇ coefficients.
• 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.
• 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.
• 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.

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