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
  • H01F1/0576—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 pressed, e.g. hot working
• • 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
  • H01F1/058—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IVa elements, e.g. Gd2Fe14C
• • 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
  • H01F1/059—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and Va elements, e.g. Sm2Fe17N2
• • 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
  • H01F41/0273—Imparting anisotropy

Definitions

• the present invention relates to the preparation of a magnetic material by forging as well as a magnetic material in powder form.
• Permanent magnets based on iron, boron and rare earths are well known Their importance in the electrical or electronic industry is increasing
• Another process consists in melting an alloy then in making it undergo a quenching on a wheel, in annealing it and in hot pressing or in coating the powder thus obtained with a resin or a polymer
• This process makes it possible to obtain bonded magnets
• the powder and the magnet obtained by the implementation of this process are most often isotropic. To obtain an anisotropic powder or magnet, it is currently necessary to use expensive processes, with low yield or with insufficient results.
• the method of the invention for the preparation of a magnetic material is characterized in that it comprises the following steps
• an alloy based on at least one rare earth, at least one transition metal and at least one other element chosen from boron and carbon is placed in a sheath, - the assembly is brought to a temperature of at least 500 ° C,
• the assembly is subjected to forging with a material deformation speed of at least 8s "' '
• the method of the invention is characterized in that it comprises the following stages - an alloy based on at least one rare earth and at least one transition metal is placed in a sheath,
• the assembly is brought to a temperature of at least 500 ° C, the assembly is subjected to forging with a material deformation speed of at least 8 s "1 ,
• the invention also relates to a magnetic material in powder form, characterized in that it has a coercivity of at least 9kOe and a persistence of at least 9kG
• the present invention applies, according to its first variant, to the preparation of magnetic materials based on at least one rare earth, at least one transition metal and at least one other element chosen from boron and carbon
• the process of the invention therefore starts from this case of alloys having the composition required to obtain the desired material
• This composition can be variable both by the nature of its constituents and by the respective proportions thereof
• alloys comprising at least one rare earth and at least one transition metal and which additionally contain at least one other element chosen from boron and carbon. Such alloys are well known
• rare earth is meant, for the whole of the description, the elements of the group constituted by the ytt ⁇ um and the elements of the periodic classification with atomic number included inclusively between 57 and 71
• the periodic classification of the elements to which reference is made for the whole description is that published in the Supplement to the Bulletin of the French Chemical Society n ° 1 (January 1966)
• the rare earth of the alloy can be neodymium or even praseodymium Alloys based on of several rare earths Mention may more particularly be made of alloys based on neodymium and praseodymium In the case of an alloy of several rare earths, the neodymium and / or praseodymium may be major (s)
• transition elements is meant the elements of columns II a to VI a, VIII, Ib and Mb
• transition elements can be more particularly here those chosen from the group comprising iron, cobalt, copper, niobium, vanadium, molybdenum and nickel, these elements can be taken alone or in combination
• the transition element is iron or even iron in combination with at least one element from the aforementioned group, iron being predominant
• the alloy may include additives such as gallium, aluminum, silicon, tin, bismuth, germanium, zirconium or titanium taken alone or in combination
• the respective proportions of rare earth, of transition metal and of the other aforementioned element can vary within wide proportions.
• the content of rare earth can be at least 1% (the percentages given HERE are atomic percentages) and it can vary between 1% and 30% approximately, more particularly between 1% and 20% approximately
• the content of third element, in particular boron can be at least 0.5% and it can vary between 0.5 and 30 % approximately, more particularly between 2 and 10% approximately
• their content can be at least 0.05% and it can vary from 0.05 to 5% approximately
• alloys By way of example of alloys, mention may very particularly be made of neodymium / iron / boron alloys, in particular those comprising also copper. Mention may also be made, as alloys which can be used more particularly in the context of the present invention, of those which have a phase corresponding with the formula TR2Fe-
• the invention also applies, according to its second variant, to the preparation of magnetic materials based on at least one rare earth, at least one transition metal and nitrogen.
• the process used in this case starts from alloys with the required composition of rare earth and transition metal to obtain the desired material All that has been said above concerning the rare earth, the transition element as well as any additives also applies HERE We can mention however more particularly the alloys based on samanum and iron from which magnetic materials based on samanum, iron and nitrogen will be obtained
• the alloys used as starting materials have no or very few magnet properties. They have in particular no or very little coercivity and anisotropy.
• the alloys which are generally used consist of mainly monocrystalline grains, of large size, at least about 10 ⁇ m Here and for the whole of the description the sizes are measured by SEM
• the alloys can be in a massive form or in the form of a powder
• the alloys are generally heterogeneous from the point of view the size of the grains, the nature of the phases and the size of the particles in the case of a powder.
• the alloy can undergo, prior to the treatment of the invention, annealing at a temperature of at least 500 ° C. under inert atmosphere
• the alloy as described above is placed in a sheath
• a cylindrical sheath is advantageously used
• the height of this sheath is preferably at least equal to the height of the alloy to be treated Its wall thickness is chosen so that '' it does not burst during forging but this thickness must remain relatively small
• the material of the sheath must be as plastic as possible at the temperature at which forging is carried out
• a metal sheath is generally used
• the sheath is in steel
• the introduction of the alloy into the sheath can be done by pouring the molten alloy into it or by any mechanical means starting from an ingot or powder
• the alloy-sheath assembly is then brought to a temperature of at least 500 ° C.
• the maximum temperature not to be exceeded is that beyond which there is a risk of significant melting of the grains of the alloy This temperature is more precisely between 600 ° C and 1100 ° C, more particularly between 800 ° C and 1000 ° C
• the alloy is brought to the indicated temperature under an inert atmosphere, for example under argon
• the alloy / sheath assembly is disposed in a sealed chamber surrounding the anvil of the forge.
• This chamber is connected to a source of inert gas and it comprises an opening through which the hammer of the forge can pass through a gasket
• the number of hammer blows is between 1 and 10
• the mechanical power of the hammer blow must be such that the constituent grains of the alloy are broken. It can also be such that part of this power is used to heat the material, allowing several successive forges, without external heating of the material. 'alloy Thus, this power can be for example at least about 1 kilowatt per gram of material (kW / g), more particularly at least 5kW / g Such a power corresponds to a material deformation rate of at least minus 8s " 1 , in particular at least 10 s -1 , more particularly at least 50s' 1 and even more particularly at least 100s * 1
• the rate of deformation of the material is defined by the expression (dh / h) / dt, dh / h designating the ratio (initial height-final height) / initial height, the height being that of the alloy / sheath assembly dt designating the duration of the crushing which is equal to dh / (v / 2), v being the speed of the hammer at the
• Such a power corresponds to devices in which the speed of the hammer is at least 0.3 ms " ⁇ , in particular at least 0.5 m. S" ' ', more particularly at least Im.s "' ', and more particularly at least 4m s - '.
• Forging can be carried out with a reduction rate of at least 2.
• the reduction rate is defined by the initial height ratio (before forging) / final height (after forging) of the alloy / sheath assembly. This rate may more particularly be at least 5.
• forging is carried out in a direction perpendicular to an axis of easy growth of the crystallites of the alloy.
• this axis of easy growth is the axis a or b of the quadratic mesh.
• Forging in this case allows the axes c to pass from an equatorial distribution to a substantially unidirectional distribution.
• the product obtained at the end of the forging is in a cylindrical planar form, or possibly in the form of a capsule when a sealed envelope has been used as described above, the internal part of which comprises the metal alloy of flow and the peripheral or external part the flow duct.
• the alloy now consists of monocrystalline grains whose average size is at most 30 ⁇ m, more particularly at most 10 ⁇ m.
• the alloy has coercivity and is anisotropic.
• the magnetization axes are aligned parallel to the direction of forging.
• the product obtained is subjected to a nitriding treatment. forging.
• the nitriding treatment is carried out in a known manner.
• the nitrogen content of the material obtained can be of the same order as that given above for boron, more particularly, it can be between 2 and 15%.
• the method of the invention may also comprise, after the forging step, other complementary steps implementing treatments which will be described below.
• the complementary treatments are preferably carried out before this nitriding step.
• a complementary treatment it is thus possible to subject the product resulting from the forging at least one annealing treatment to improve its magnetic properties.
• Different types of annealing treatment can be considered.
• a first type is made at a temperature which can be between 700 ° C. and 1100 ° C.
• the treatment is preferably carried out under an inert atmosphere, for example under argon.
• the duration of the treatment can be between a few minutes and a few hours.
• Another type of annealing treatment can be carried out at a temperature of between 400 ° C. and 700 ° C., preferably also under an inert atmosphere of the argon type.
• the duration of the treatment can be between a few minutes and a few hours.
• Hydriding and dehydrating treatments are known.
• the hydriding of the material can be carried out under a hydrogen atmosphere (for example at least equal to 0.1 MPa) at ambient temperature or else by thermally activating the material in an atmosphere containing hydrogen.
• the material can be thermally activated up to a temperature below 500 ° C, preferably below 300 ° C.
• Dehydriding can be achieved by heating the hydrated material to a temperature of at least 500 ° C under vacuum. The temperature and the heating time are chosen so as to obtain complete dehydriding.
• the dehydriding treatment may optionally be followed by annealing of the first and / or of the second type mentioned above.
• this material has a coercivity of at least 9kOe, more particularly of at least 9.5kOe and even more particularly of at least 10kOe in combination with a remanence of at least 9kG, more particularly of at least 9, 5kG and even more particularly at least 10kG.
• the material may have each of the coercivity values given above in combination with each of the remanence values also given above, for example a coercivity of 9kOe in combination with a remanence of 9.5kG.
• the material has a crystalline texture which makes it magnetically anisotropic.
• the particles which constitute the powder themselves are made up not of a single monocrystalline grain but of several monocrystalline grains with an average size of at least minus 0.1 ⁇ m.
• the particles may have a size of a few tens of microns, in particular between approximately 10 and approximately 200 ⁇ m, more particularly between approximately 10 ⁇ m and approximately 100 ⁇ m, and be made up of ten grains of a few microns each.
• the material consists of the constituent elements which have been given above for the alloy and what has been described on this subject also applies here, the material being in particular based on at least one rare earth, at least one transition metal and at least one other element chosen from boron, carbon and nitrogen.
• the alloy used corresponds to the formula for examples 1 and 2, to the formula 5 for Example 3 and the formula
• the tests are carried out in a cylindrical steel sheath. In certain cases the alloy undergoes two hammer blows (first forging and second forging).
• T2 temperature during the second forging
• Tr 2 total reduction rate after the second forging
• hammer speed during the first forging 2 '• hammer speed during the second forging
• P- j mechanical power of the first hammer blow
• P mechanical power of the second hammer blow

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Hard Magnetic Materials (AREA)
• Soft Magnetic Materials (AREA)
• Manufacturing Cores, Coils, And Magnets (AREA)
• Powder Metallurgy (AREA)

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• 1998
  • 1998-05-28 FR FR9806745A patent/FR2779267B1/fr not_active Expired - Fee Related
• 1999
  • 1999-05-26 DE DE69906513T patent/DE69906513T2/de not_active Expired - Lifetime
  • 1999-05-26 AT AT99922227T patent/ATE236450T1/de not_active IP Right Cessation
  • 1999-05-26 JP JP2000551403A patent/JP3668134B2/ja not_active Expired - Fee Related
  • 1999-05-26 WO PCT/FR1999/001234 patent/WO1999062080A1/fr active IP Right Grant
  • 1999-05-26 CN CNB998088439A patent/CN1142562C/zh not_active Expired - Lifetime
  • 1999-05-26 AU AU39353/99A patent/AU3935399A/en not_active Abandoned
  • 1999-05-26 US US09/701,286 patent/US6592682B1/en not_active Expired - Lifetime
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