TH38326B - Iron-based nanocomposite rare earth alloys And a method for producing such magnets - Google Patents

Abstract

DC60 (06/08/45) A rare earth alloy nanocomposite magnet predominantly iron has a composition represented by the general formula (Fe1-mTm)100-x-y-zQxRyTiz, where T is at least one material chosen from the Co and Ni-containing groups, Q is at least one material chosen from the B and C-containing groups, R is at least one rare earth material including, mostly without, La or Ce, and the molar proportions of x, y, z, and m better then satisfy the inequalities of: 10 at% less than x less than or equal to 17 at%; 7 at% less than or equal to y less than 10 at%; z less than or equal to 6 at%; and 0 less than or equal to m less than or equal to 0.5, respectively. The magnet includes crystal grains of the R2T14Q compound with an average grain size of approximately 20 nm to approximately 200 nm and a ferromagnetic iron boride. The majority of the boride found in the intergranular environment of the R2T14Q compound crystalline structure is dispersed in or in the form of a covering film around the crystalline grains, at least partially covering the surface of the R2T14Q compound crystalline grains. The iron-dominant rare earth alloy nanocomposite magnet has a composition represented by the general formula (Fe1-mTm)100-x-y-zQxRyTiz, where T is at least one material chosen from the group containing Co and Ni, Q is at least one material chosen from the group containing B and C, R is at least one rare earth material including, mostly, La or Ce, and the molar proportions of x, y, z, and m better satisfy the inequality of: 10 at% < x <= 17 at%; 7 at% <= y < 10 at%; <= z <= 6 at%; And 0 is less than m and ≤ 0.5, respectively. The magnets include crystalline grains of R2T14Q compounds with an average grain size of approximately 20 nm to approximately 200 nm, and borides predominantly ferromagnetic iron found in the environment between the crystalline grains of the R2T14Q compounds. These borides are dispersed in or exist as a film surrounding the crystalline grains to at least partially cover the surface of the crystalline grains of the R2T14Q compounds.

Claims (19)

1. A rare earth alloy nanocomposite magnet with an element represented by the general formula: (Fel-mTm)100-x-y-zQxRyTiz, where T is at least one element chosen from the Co and Ni-containing groups; Q is at least one element chosen from the B and C-containing groups; and R is at least one rare earth element excluding La or Cc, with mole fractions x, y, z, and m satisfying the inequalities: 10 at% < x <= 17 at%; 7 at% <= y < 10 at%; 0.5 at <= z < 6 at% and 0 <= m <= 0.5, respectively; where the crystal grains of the R2T14Q compound have an average grain size of 20 nm to 200 nm; the crystal grains of the ferromagnetic iron-based boride have an average grain size smaller than the crystal grain size of the R2T14Q compound; And ferromagnetic iron-based borides are the weak magnetic phase and are dispersed around the crystal grains or appear as a film above the crystal grains, covering at least some of the crystal surface of the R2T14Q compound. 2. The magnetism of claim 1, where the mole fractions x, y, and z satisfy the inequalities: 10 at% < x <= 15 at%; 7 at% <= y <= 9.3 at%; and 1.5 at% <= z <= 5 at%. 3. Magnets of claim 1, where the magnets comprise crystalline forms including R2T14Q compounds and borides with 95% or more ferromagnetic iron by volume in total; and indeterminate forms at 5% or less by volume. 4. Magnet of claim 3, where the magnet consists of a compound of the type R2T14Q at 65% by volume to 85% by volume. 5. Magnetism of Claim 1 where the crystal grains of the compound R2T14Q have a Ti concentration of 2 at% or less, and the Ti concentration in the intergranular environment of the crystal grains of the compound R2T14Q is higher than the Ti concentration within the crystal grains of the compound R2T14Q. 6. Magnetism of claim 5 where the Ti concentration in the intergranular environment of the R2T14Q compound is 7at% or greater. 7. The magnetism of claim 1, where the ferromagnetic iron-based boride has an average size of 50 nm or less as measured along the outer thickness of the crystal grain. 8. Magnetism of claim 1, where a ferromagnetic iron-based boride exists as a film with an average thickness of 20 nm or less on the intergranular crystalline surface of an R2T14Q compound. 9. Magnetism of claim 1, where a ferromagnetic iron-based boride exists in the intergranular crystal structure of the R2T14Q compound and has an average principal axis length of 1 nm to 50 nm. 10. Magnetism of Claim 1, where on any cross-section of the magnet, the crystal grains of the R2T14Q compound have a larger average size than those of the ferromagnetic iron-based boride. 11. Magnetism of claim 1, where the mole fractions x, y, and z satisfy the inequalities: 10 at% < x <= 14 at% and 0.5 at% <= z <= 14 at%. 12. Magnet of Claim 1 where the iron-based boride contains at least one of Fe3B and/or Fe23B6. 13. Magnet of Claim 1, where the magnet is in the form of a thin strip with a thickness of 10 micrometers to 300 micrometers. 14. The magnet of claim 1, which is crushed into powder particles. 15. Magnetism of claim 14 where the powder particles have an average particle size of 30 µm to 250 µm. 16. Magnetism of claim 1, where the magnet has a residual magnetic flux BL 0.80T or greater, maximum energy product (BH) min 100 kJ/m.3 or greater, and forced condition HcJ 480 kA/m or greater. 17. Magnet of Claim 1 where the magnet has a residual magnetic flux Br 0.85T or greater and a maximum energy product (BH)max 120 kJ/m.3 18. Bonded magnets obtained by magnetic powder casting, consisting of iron-based rare earth alloy magnetic powder according to claim 14, with a resin binder. 19. Bonded magnets obtained by magnetic powder casting, consisting of iron-based rare earth alloy magnetic powder according to claim 15, with a resin binder.