EP1638716A1 - Verfahren und vorrichtung zur schmelzmetallurgischen herstellung von leitfähigen legierungen - Google Patents
Verfahren und vorrichtung zur schmelzmetallurgischen herstellung von leitfähigen legierungenInfo
- Publication number
- EP1638716A1 EP1638716A1 EP04766059A EP04766059A EP1638716A1 EP 1638716 A1 EP1638716 A1 EP 1638716A1 EP 04766059 A EP04766059 A EP 04766059A EP 04766059 A EP04766059 A EP 04766059A EP 1638716 A1 EP1638716 A1 EP 1638716A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- coils
- alloys
- coil
- melt
- phase shift
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B13/00—Single-crystal growth by zone-melting; Refining by zone-melting
- C30B13/26—Stirring of the molten zone
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D25/00—Special casting characterised by the nature of the product
- B22D25/06—Special casting characterised by the nature of the product by its physical properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/02—Use of electric or magnetic effects
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B13/00—Single-crystal growth by zone-melting; Refining by zone-melting
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/52—Alloys
Definitions
- the invention relates to the field of materials science and relates to a method and a device for the melt-metallurgical production of conductive alloys, which can be used, for example, as a material for high-performance permanent magnets.
- the ferromagnetic properties of the rare earth magnets are based on the excellent hard magnetic properties of the Nd 2 Fe ⁇ 4 B phase ( ⁇ phase) with their structural anisotropy, which was described in 1984 by Sagawa et al .: J. Appl. Phys. 55 (1984) 2083 and Croat et al .: J. Appl. Phys. 55 (1984) 2078.
- the ternary phase diagram Nd-Fe-B in the form used today uses the work of Schneider et al .: Z. Metallkd. 77 (1986) 755.
- Nd-Fe-B magnets differ considerably from the intrinsic properties (magnetocrystalline anisotropy, saturation magnetization) of the Nd 2 Fe- ⁇ B phase, since the magnetic properties of the permanent magnetic Alloy are extremely sensitive to the morphology (extrinsic properties).
- Nd-Fe-B permanent magnets The most common manufacturing method for Nd-Fe-B permanent magnets is powder metallurgy, including in particular the sintering process.
- the ingot production of sintered magnets usually takes place in casting processes that take place close to the thermodynamic equilibrium.
- Annealing processes serve to homogenize and convert the ⁇ -Fe phase into the hard magnetic Nd 2 Fe- ⁇ B phase via a peritectic reaction, although increased grain growth is disadvantageous.
- fine-grained coercive powder can be produced from the cast material in the HDDR process (hydrogenation, disproportionation, desorption, recombination) (IR Harris, inter alia: J. Less-Common Met., 106 (1985) L1).
- IR Harris inter alia: J. Less-Common Met., 106 (1985) L1
- the method for producing a uniaxial texture is hot pressing (T. Shimoda, inter alia: J. Appl. Phys. 64 (1988) 5290).
- the powder is pulsed in a rubber casting mold with the simultaneous influence of a strong one
- the object of the present invention is to provide a method and a device for the melt metallurgical production of conductive alloys, by means of which the nucleation, growth and conversion behavior of the phases forming and thus also the structure of the solidified alloy can be influenced.
- the flow in the area of the melt is influenced by an electromagnetically generated volume force in the direction of a currentless state.
- Peritectic alloys or magnet alloys, in particular based on Nd-Fe-B, can advantageously be used as conductive alloys.
- This electromagnetic volume force is generated by using a second induction coil, which is arranged above or below the primary induction coil, and a phase shift between the electrical currents in the two induction coils is thereby realized.
- the secondary coil can be connected to the power supply of the primary coil, but it can also advantageously have no connection to a power source.
- phase shift of the electrical currents is advantageously generated in the resonant circuits of the two induction coils, the phase shift of the electrical currents advantageously being realized by regulating the capacitive force in the secondary resonant circuit and particularly advantageously a phase shift of the electrical currents of 0 °.
- the latter can be achieved by connecting the two induction coils in series.
- the amplitude of the currents is limited by an ohmic resistor, with the same amplitude of the currents being advantageously set in both circuits in order to ensure homogeneous melting.
- the electromagnetically generated volume force is influenced by regulating the frequency of the currents and / or the current strength and / or the vertical spacing of the coils and / or the inner diameter of the coils and / or the capacitance and the ohmic resistance in the secondary resonant circuit, it being particularly advantageous to set a vertical distance between the two coils which corresponds to the radius of the starting material.
- a penetration depth ⁇ of the magnetic field into the material belonging to the frequency ⁇ of the primary current, ⁇ (2 / ⁇ ) "1/2 , which corresponds to the radius of the starting material, is set, where ⁇ is the magnetic permeability and ⁇ is the electrical conductivity of the material are at the respective temperature.
- the method according to the invention achieves a greatly reduced melt convection, which surprisingly has a strong effect on the nucleation and growth behavior of primary and secondary growing phases.
- the kinetics of nucleation and growth processes during solidification are affected even near the liquidus temperature.
- the nucleation temperature of ⁇ -Fe nuclei which transform to ⁇ -Fe at lower temperatures in a solid state, is 1220 ° C.
- an extended lifetime of the metastable phases that form and a delayed nucleation of the subsequent stable phases is also, for example, an extended lifetime of the metastable phases that form and a delayed nucleation of the subsequent stable phases.
- a secondary coil is arranged above or below the primary coil, both coils having their own resonant circuit, by means of which a phase shift can be regulated in a controllable manner.
- a further advantageous embodiment of the invention is if the secondary coil is arranged above the primary coil for realizing a melt flow upward on the free surface of the melt zone or if the secondary coil is arranged under the primary coil for realizing a melt flow downward on the free surface of the melt zone ,
- the capacitance in the secondary circuits and / or the vertical distance between the two induction coils is selected such that the double vortex structure theoretically associated with each individual coil overlaps the flow in such a way that a significant reduction in the flow is achieved inside the melt.
- the flow in the molten volume is influenced by additionally generated electromagnetic forces in such a way that the melting flow is aimed at being as calm as possible. This has resulted in the quality of the solidified structure being improved by the solution according to the invention and, in the case of the production of magnetic alloys based on Nd-Fe-B, the volume fraction of the soft magnetic ⁇ -Fe phase being able to be substantially reduced.
- the device according to the invention consists of the induction coil (primary coil) known in the devices according to the prior art, to which a second induction coil (secondary coil) is added, both coils having their own resonant circuit, by means of which a phase shift can be regulated in a controllable manner.
- the secondary coil is not connected to a power supply and this circuit of the secondary coil has a capacitor with adjustable capacitance and an adjustable ohmic resistance.
- Volume force can be set, which leads to a strong flow calming in the
- the flow patterns in the melting zone were numerically simulated taking into account all types of convection (Marangoni, electromagnetic due to HF heating, buoyancy, mechanical rotation of the rod).
- the electromagnetic field equilibria in the material exactly and not calculated as usual with the approximation of an electrical surface current. This, in turn, is necessary in order to be able to influence the convection and thus the flow conditions on the solidification front in a controlled manner by modifying the electromagnetic fields.
- a targeted influencing of the volume force and thus the flow in the melt is possible in the production of conductive alloys, in particular peritectic alloys and especially magnetic alloys based on Nd-Fe-B.
- this can be regulated from the setting of a strong convection through a quasi-currentless state to the reversal of the flow direction in front of the solidification front of the melt.
- the regulation of the phase shift of the currents and thus the regulation of the flow-driving volumetric force can be achieved, for example, by regulating the frequency of the currents and / or the current strength and / or the vertical distance between the coils and / or the inside diameter of the coils and / or the capacitance and ohmic Resistance in the secondary resonant circuit. If these parameters are changed, the flow is significantly influenced.
- the method according to the invention can be used for melting any large amount of material in a crucible-free process, but also for processes using crucibles.
- conductive alloys in which a metastable mixture gap occurs which should be avoided are Cu-Co compounds and Fe-Cu compounds.
- Nb-Cu is used as a high-strength conductor material. In addition to the primary phase Nb, a long residual solidification area arises here, which leads to undesired inhomogeneities.
- Nd-Fe-B rod with a diameter of 6mm of the stoichiometric composition Ndn. 8 Fe 8 2.3B5.6 (at.%) Is melted inductively without crucibles in a floating zone system.
- the floating zone system consists of the components of a water-cooled vacuum recipient with pull-turn drives and clamps for the rod-shaped material to be examined, devices for induction heating, windows for visual and camera observation, and pyrometric temperature measurement.
- the primary coil is operated via a 250 kHz generator.
- the secondary coil is located below the primary coil and has no power connection. Both coils are connected in a resonant circuit with a capacitor and an ohmic resistor (Fig. 1).
- phase shift of the currents of the primary and secondary coils which is set to a value of 840 nF and the ohmic resistance to a value of 51.2 m ⁇ by setting the capacitance in the secondary resonant circuit, results in a strong, easily controllable volume force on the melt, with which Help the flow to an almost flow-free state is set (Fig. 2a).
- FIGS. 2a and 2b show a larger ⁇ -Fe volume fraction in the microstructure that was produced with a strong melt flow.
- a significantly lower ⁇ -Fe volume fraction is formed under the manufacturing conditions according to the invention with a calm melt flow.
- the result was verified by measuring the volume fraction of the ⁇ -Fe phase using a vibration magnetometer. It is 12.6 mass% for the sample in Fig. 2a and 26.4 mass% for the sample in Fig. 2b.
- volume fraction of the ⁇ -Fe phase in a sample which was produced according to the prior art without influencing the melt flow was determined.
- a value of 22.5 mass% was determined.
- the floating zone system consists of the components of a water-cooled vacuum recipient with pull-turn drives and clamps for the rod-shaped material to be examined, devices for induction heating, windows for visual and camera observation, and pyrometric temperature measurement.
- the primary coil is operated via a 250 kHz generator.
- the secondary coil is located below the primary coil and has no power connection. Both coils are connected in a resonant circuit with a capacitor and an ohmic resistor according to Example 1.
- phase shift of the currents of the primary and secondary coils which is set to a value of 800 nF and the ohmic resistance to a value of 51.2 m ⁇ by setting the capacitance in the secondary resonant circuit, results in a strong, easily controllable volume force on the melt, with which Help the flow to be set to an almost flow-free state.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Continuous Casting (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10328618A DE10328618B4 (de) | 2003-06-20 | 2003-06-20 | Verfahren und Vorrichtung zur schmelzmetallurgischen Herstellung von Magnetlegierungen auf Nd-Fe-B-Basis |
PCT/EP2004/051169 WO2004112993A1 (de) | 2003-06-20 | 2004-06-18 | Verfahren und vorrichtung zur schmelzmetallurgischen herstellung von leitfähigen legierungen |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1638716A1 true EP1638716A1 (de) | 2006-03-29 |
Family
ID=33520972
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP04766059A Withdrawn EP1638716A1 (de) | 2003-06-20 | 2004-06-18 | Verfahren und vorrichtung zur schmelzmetallurgischen herstellung von leitfähigen legierungen |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1638716A1 (de) |
DE (1) | DE10328618B4 (de) |
WO (1) | WO2004112993A1 (de) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007122231A1 (de) * | 2006-04-24 | 2007-11-01 | Forschungsverbund Berlin E.V. | Vorrichtung zur herstellung von kristallen aus elektrisch leitfähigen schmelzen |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE311295C (de) * | ||||
DE905663C (de) * | 1944-11-15 | 1954-03-04 | Paul Esser | Metallspritzverfahren zum dichten Verschliessen von lochartigen Ausbruechen in Gusskoerpern |
GB885041A (en) * | 1959-04-07 | 1961-12-20 | Radyne Ltd | Improvements in or relating to zone melting |
US4220626A (en) * | 1978-04-13 | 1980-09-02 | Monsanto Company | RF Induction heating circuits for float zone refining of semiconductor rods |
JPS58163566A (ja) * | 1982-03-24 | 1983-09-28 | Hitachi Metals Ltd | Fe−Cr−Co系磁石合金の製造方法 |
US5033948A (en) * | 1989-04-17 | 1991-07-23 | Sandvik Limited | Induction melting of metals without a crucible |
FR2646858B1 (fr) * | 1989-05-11 | 1992-07-03 | Snecma | Procede de refusion de materiaux metalliques avec decantation inclusionnaire |
FR2665249A1 (fr) * | 1990-07-26 | 1992-01-31 | Dauphine Ets Bonmartin Laminoi | Four de fusion par induction en creuset froid. |
DE69221245T2 (de) * | 1991-04-25 | 1997-12-11 | Seiko Epson Corp | Verfahren zur herstellung eines permanentmagnetes aus seltenen erden |
US5246060A (en) * | 1991-11-13 | 1993-09-21 | Aluminum Company Of America | Process for ingot casting employing a magnetic field for reducing macrosegregation and associated apparatus and ingot |
US5253696A (en) * | 1992-04-08 | 1993-10-19 | Misra Asoka K | Method and apparatus for controlling solidification of metals and other materials |
ATE158669T1 (de) * | 1993-06-14 | 1997-10-15 | Santoku Metal Ind | Verfahren zur herstellung eines dauermagneten aus seltenerdmetall, bor und eisen |
-
2003
- 2003-06-20 DE DE10328618A patent/DE10328618B4/de not_active Expired - Fee Related
-
2004
- 2004-06-18 WO PCT/EP2004/051169 patent/WO2004112993A1/de active Application Filing
- 2004-06-18 EP EP04766059A patent/EP1638716A1/de not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO2004112993A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2004112993A1 (de) | 2004-12-29 |
DE10328618B4 (de) | 2008-04-24 |
DE10328618A1 (de) | 2005-01-13 |
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DAX | Request for extension of the european patent (deleted) | ||
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: PRIEDE, JANIS Inventor name: GERBETH, GUNTER Inventor name: FILIP, OCTAVIAN Inventor name: SCHULTZ, LUDWIG Inventor name: HERMANN, REGINA |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: FORSCHUNGSZENTRUM DRESDEN - ROSSENDORF E.V. Owner name: LEIBNIZ-INSTITUT FUER FESTKOERPER- UND WERKSTOFFFO |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: FORSCHUNGSZENTRUM DRESDEN - ROSSENDORF E.V. Owner name: LEIBNIZ-INSTITUT FUER FESTKOERPER- UND WERKSTOFFFO |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: HELMHOLTZ-ZENTRUM DRESDEN - ROSSENDORF E.V. Owner name: LEIBNIZ-INSTITUT FUER FESTKOERPER- UND WERKSTOFFFO |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 20131231 |