# US 2002/0153064 A1 · Magnetic powder, manufacturing method of magnetic powder and bonded magnets > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2002/0153064 A1 - Document ID: US20020153064A1 - Status: Published application - Kind: A1 - Application number: 09/875,789 - Filed: 2001-06-06 - Published: 2002-10-24 - Earliest claimed: 2000-06-06 - Assignees: Seiko Epson Corporation - Inventors: Akira Arai; Hiroshi Kato - Web page: https://patentgrep.com/patent/US20020153064A1 ## CPC - H01F 1/0579: {with exchange spin coupling between hard and soft nanophases, e.g. nanocomposite spring magnets} - B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance - H01F 1/0578: {bonded together} - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES ## Abstract Disclosed herein is a magnetic powder which can provide magnets having excellent magnetic properties and having excellent reliability especially excellent heat stability. The magnetic powder is composed of an alloy composition represented by Rx(Fe1−aCoa)100−x−y−zByMz (where R is at least one kind of rare-earth element excepting Dy, M is at least one kind of element selected from Ti, Cr, Nb, V, Mo, Hf, W, Mn, Zr and Dy, x is 7.1-9.9 at %, y is 4.6-8.0 at %, z is 0.1-3.0 at %, and a is 0-0.30), and the magnetic powder being constituted from a composite structure having a soft magnetic phase and a hard magnetic phase, wherein when the magnetic powder is mixed with a binding resin and then the mixture is subjected to injection molding or extrusion molding to form a bonded magnet having a density ρ[Mg/m3], the maximum magnetic energy product (BH)max[kJ/m3] of the bonded magnet at a room temperature satisfies the relationship represented by the formula (BH)max/ρ2[×10−9J·m3/g2]≧2.10, and the intrinsic coercive force HCJ of the bonded magnet at a room temperature is in the range of 400-760 kA/m. ## Claims ### Claim 1 Magnetic powder composed of an alloy composition represented by Rx(Fe1−aCoa)100−x−y−zByMz (where R is at least one kind of rare-earth element excepting Dy, M is at least one kind of element selected from Ti, Cr, Nb, V, Mo, Hf, W, Mn, Zr and Dy, x is 7.1-9.9 at %, y is 4.6-8.0 at %, z is 0.1-3.0 at %, and a is 0-0.30), and the magnetic powder being constituted from a composite structure having a soft magnetic phase and a hard magnetic phase, wherein when the magnetic powder is mixed with a binding resin and then the mixture is subjected to injection molding or extrusion molding to form a bonded magnet having a density ρ[Mg/m3], a maximum magnetic energy product (BH)max[kJ/m3] of the bonded magnet at room temperature satisfies a relationship represented by a formula of (BH)max/ρ2[×10−9J·m3/g2]≧2.10, and an intrinsic coercive force HCJ of the bonded magnet at room temperature is in a range of 400-760 kA/m. ### Claim 2 (depends on 1) The magnetic powder as claimed in claim 1, wherein a remanent magnetic flux density Br[T] of the bonded magnet at room temperature satisfies a relationship represented by a formula of Br/ρ[×10−6T·m3/g]≧0.125. ### Claim 3 Magnetic powder composed of an alloy composition represented by Rx(Fe1−aCoa)100−x−y−zByMz (where R is at least one kind of rare-earth element excepting Dy, M is at least one kind of element selected from Ti, Cr, Nb, V, Mo, Hf, W, Mn, Zr and Dy, x is 7.1-9.9 at %, y is 4.6-8.0 at %, z is 0.1-3.0 at %, and a is 0-0.30), and the magnetic powder being constituted from a composite structure having a soft magnetic phase and a hard magnetic phase, wherein when the magnetic powder is mixed with a binding resin and then the mixture is subjected to injection molding or extrusion molding to form a bonded magnet having a density ρ[Mg/m3], a remanent magnetic flux density Br[T] of the bonded magnet at room temperature satisfies a relationship represented by a formula of Br/ρ[×10−6T·m3/g]≧0.125 and an intrinsic coercive force HCJ of the bonded magnet at room temperature is in a range of 400-760 kA/m. ### Claim 4 (depends on 1) The magnetic powder as claimed in claim 1, wherein the magnetic powder is obtained by milling a melt spun ribbon. ### Claim 5 (depends on 4) The magnetic powder as claimed in claim 4, wherein a thickness of the melt spun ribbon is 10-40 μm. ### Claim 6 (depends on 4) The magnetic powder as claimed in claim 4, wherein the melt spun ribbon is obtained by colliding a molten alloy of a magnetic material onto a circumferential surface of a cooling roll which is rotating to cool and then solidify it. ### Claim 7 (depends on 6) The magnetic powder as claimed in claim 6, wherein the cooling roll includes a roll base made of a metal or an alloy and an outer surface layer provided on an outer peripheral portion of the roll base to constitute the circumferential surface, in which the outer surface layer of the cooling roll has a heat conductivity lower than a heat conductivity of the roll base. ### Claim 8 (depends on 7) The magnetic powder as claimed in claim 7, wherein the outer surface layer of the cooling roll is formed of a ceramic. ### Claim 9 (depends on 1) The magnetic powder as claimed in claim 1, wherein said R comprises rare-earth elements mainly containing Nd and/or Pr. ### Claim 10 (depends on 1) The magnetic powder as claimed in claim 1, wherein said R includes Pr and its ratio with respect to a total mass of said R is 5-75%. ### Claim 11 (depends on 1) The magnetic powder as claimed in claim 1, wherein the composite structure includes a nanocomposite structure. ### Claim 12 (depends on 1) The magnetic powder as claimed in claim 1, wherein the magnetic powder is subjected to a heat treatment at least once during a manufacturing process or after its manufacture. ### Claim 13 (depends on 1) The magnetic powder as claimed in claim 1, wherein a mean crystal grain size of the magnetic powder is 5-50 nm. ### Claim 14 (depends on 1) The magnetic powder as claimed in claim 1, wherein an average particle size of the magnetic powder is 0.5-150 μm. ### Claim 15 A method of manufacturing magnetic powder, in which a melt spun ribbon is obtained by colliding a molten alloy of a magnetic material onto a circumferential surface of a cooling roll which is rotating to cool and then solidify it, and then thus obtained melt spun ribbon is milled to obtain the magnetic powder, in which the magnetic powder is composed of an alloy composition represented by Rx(Fe1−aCoa)100−x−y−zByMz (where R is at least one kind of rare-earth element excepting Dy, M is at least one kind of element selected from Ti, Cr, Nb, V, Mo, Hf, W, Mn, Zr and Dy, x is 7.1-9.9 at %, y is 4.6-8.0 at %, z is 0.1-3.0 at %, and a is 0-0.30), and the magnetic powder being constituted from a composite structure having a soft magnetic phase and a hard magnetic phase, wherein when the magnetic powder is mixed with a binding resin and then the mixture is subjected to injection molding or extrusion molding to form a bonded magnet having a density ρ[Mg/m3], a maximum magnetic energy product (BH)max[kJ/m3] of the bonded magnet at room temperature satisfies a relationship represented by a formula of (BH)max/ρ2[×10−9J·m3/g2]≧2.10, and an intrinsic coercive force HCJ of the bonded magnet at room temperature is in a range of 400-760 kA/m. ### Claim 16 A method of manufacturing magnetic powder, in which a melt spun ribbon is obtained by colliding a molten alloy of a magnetic material onto a circumferential surface of a cooling roll which is rotating to cool and then solidify it, and then thus obtained melt spun ribbon is milled to obtain the magnetic powder, in which the magnetic powder being composed of an alloy composition represented by Rx(Fe1−aCoa)100−x−y−zByMz (where R is at least one kind of rare-earth element excepting Dy, M is at least one kind of element selected from Ti, Cr, Nb, V, Mo, Hf, W, Mn, Zr and Dy, x is 7.1-9.9 at %, y is 4.6-8.0 at %, z is 0.1-3.0 at %, and a is 0-0.30), and the magnetic powder being constituted from a composite structure having a soft magnetic phase and a hard magnetic phase, wherein when the magnetic powder is mixed with a binding resin and then the mixture is subjected to injection molding or extrusion molding to form a bonded magnet having a density ρ[Mg/m3], a remanent magnetic flux density Br[T] of the bonded magnet at room temperature satisfies a relationship represented by a formula of Br/ρ[×10−6T·m3/g]≧0.125, and an intrinsic coercive force HCJ of the bonded magnet at room temperature is in a range of 400-760 kA/m. ### Claim 17 A bonded magnet manufactured by mixing magnetic powder with a binding resin and then subjecting the mixture to injection molding or extrusion molding, in which the magnetic powder is composed of an R—TM—B based alloy having at least one element selected from Ti, Cr, Nb, V, Mo, Hf, W, Mn, Zr and Dy (where R is at least one kind of rare-earth element excepting Dy, and TM is a transition metal mainly containing Fe), the bonded magnet being characterized in that when a density of the bonded magnet is ρ[Mg/m3], a maximum magnetic energy product (BH)max[kJ/m3] of the bonded magnet at room temperature satisfies a relationship represented by a formula of (BH)max/ρ2[×10−9J·m3/g2]≧2.10, and an intrinsic coercive force HCJ of the bonded magnet at room temperature is in a range of 400-760 kA/m. ### Claim 18 (depends on 17) The bonded magnet as claimed in claim 17, wherein a remanent magnetic flux density Br[T] of the bonded magnet at room temperature satisfies a relationship represented by a formula of Br/ρ[×10−6T·m3g]≧0.125. ### Claim 19 A bonded magnet manufactured by mixing magnetic powder with a binding resin, and then subjecting the mixture to injection molding or extrusion molding, wherein the magnetic powder being composed of an R—TM—B based alloy having at least one element selected from Ti, Cr, Nb, V, Mo, Hf, W, Mn, Zr and Dy (where R is at least one kind of rare-earth element excepting Dy, and TM is a transition metal mainly containing Fe), the bonded magnet being characterized in that when a density of the bonded magnet is ρ[Mg/m3], a remanent magnetic flux density Br[T] of the bonded magnet at room temperature satisfies a relationship represented by a formula of Br/ρ[×10−6T·m3/g]≧0.125, and an intrinsic coercive force HCJ of the bonded magnet at room temperature is in a range of 400-760 kA/m. ### Claim 20 (depends on 17) The bonded magnet as claimed in claim 17, wherein the magnetic powder is composed of an alloy composition represented by Rx(Fe1−aCoa)100−x−y−zByMz (where R is at least one kind of rare-earth element excepting Dy, M is at least one kind of element selected from Ti, Cr, Nb, V, Mo, Hf, W, Mn, Zr and Dy, x is 7.1-9.9 at %, y is 4.6-8.0 at %, z is 0.1-3.0 at %, and a is 0-0.30), and the magnetic powder is constituted from a composite structure having a soft magnetic phase and a hard magnetic phase. ### Claim 21 (depends on 17) The bonded magnet as claimed in claim 17, wherein a maximum magnetic energy product (BH)max[kJ/m3] is equal to or greater than 40 kJ/m3. ### Claim 22 (depends on 16) The bonded magnet as claimed in claim 16, wherein an absolute value of an irreversible flux loss (initial flux loss) is equal to or less than 6.2%. ### Claim 23 (depends on 3) The magnetic powder as claimed in claim 3, wherein the magnetic powder is obtained by milling a melt spun ribbon. ### Claim 24 (depends on 24) The magnetic powder as claimed in claim 24, wherein a thickness of the melt spun ribbon is 10-40 μm. ### Claim 25 (depends on 24) The magnetic powder as claimed in claim 24, wherein the melt spun ribbon is obtained by colliding a molten alloy of a magnetic material onto a circumferential surface of a cooling roll which is rotating to cool and then solidify it. ### Claim 26 (depends on 25) The magnetic powder as claimed in claim 25, wherein the cooling roll includes a roll base made of a metal or an alloy and an outer surface layer provided on an outer peripheral portion of the roll base to constitute the circumferential surface, in which the outer surface layer of the cooling roll has a heat conductivity lower than a heat conductivity of the roll base. ### Claim 27 (depends on 26) The magnetic powder as claimed in claim 26, wherein the outer surface layer of the cooling roll is formed of a ceramic. ### Claim 28 (depends on 3) The magnetic powder as claimed in claim 3, wherein said R comprises rare-earth elements mainly containing Nd and/or Pr. ### Claim 29 (depends on 3) The magnetic powder as claimed in claim 3, wherein said R includes Pr and its ratio with respect to a total mass of said R is 5-75%. ### Claim 30 (depends on 3) The magnetic powder as claimed in claim 3, wherein the composite structure includes a nanocomposite structure. ### Claim 31 (depends on 3) The magnetic powder as claimed in claim 3, wherein the magnetic powder is subjected to a heat treatment at least once during a manufacturing process or after its manufacture. ### Claim 32 (depends on 3) The magnetic powder as claimed in claim 3, wherein a mean crystal grain size of the magnetic powder is 5-50 nm. ### Claim 33 (depends on 3) The magnetic powder as claimed in claim 3, wherein an average particle size of the magnetic powder is 0.5-150 μm. ### Claim 34 (depends on 19) The bonded magnet as claimed in claim 19, wherein the magnetic powder is composed of an alloy composition represented by Rx(Fe1−aCoa)100−x−y−zByMz (where R is at least one kind of rare-earth element excepting Dy, M is at least one kind of element selected from Ti, Cr, Nb, V, Mo, Hf, W, Mn, Zr and Dy, x is 7.1-9.9 at %, y is 4.6-8.0 at %, z is 0.1-3.0 at %, and a is 0-0.30), and the magnetic powder is constituted from a composite structure having a soft magnetic phase and a hard magnetic phase. ### Claim 35 (depends on 19) The bonded magnet as claimed in claim 19, wherein a maximum magnetic energy product (BH)max[kJ/m3] is equal to or greater than 40 kJ/m3. ### Claim 36 (depends on 17) The bonded magnet as claimed in claim 17, wherein an absolute value of an irreversible flux loss (initial flux loss) is equal to or less than 6.2%.