EP0319786A1 - Process for preparing secondary powder particles with a nanocrystalline structure and with a closed surface - Google Patents

Process for preparing secondary powder particles with a nanocrystalline structure and with a closed surface Download PDF

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EP0319786A1
EP0319786A1 EP88119570A EP88119570A EP0319786A1 EP 0319786 A1 EP0319786 A1 EP 0319786A1 EP 88119570 A EP88119570 A EP 88119570A EP 88119570 A EP88119570 A EP 88119570A EP 0319786 A1 EP0319786 A1 EP 0319786A1
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secondary powder
nanocrystalline structure
powder
elements
nanocrystalline
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French (fr)
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EP0319786B1 (en
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Hans Dr-Ing. Grewe
Wolfgang Dr. Schlump
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Fried Krupp AG Hoesch Krupp
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Fried Krupp AG Hoesch Krupp
Fried Krupp AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/002—Making metallic powder or suspensions thereof amorphous or microcrystalline
    • B22F9/004—Making metallic powder or suspensions thereof amorphous or microcrystalline by diffusion, e.g. solid state reaction
    • B22F9/005—Transformation into amorphous state by milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy

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  • Materials with a nanocrystalline structure can be produced in such a way that crystals with a diameter of a few nanometers are compacted into a solid under high pressure (a few MPa).
  • all methods that enable the production of sufficiently small crystals with a "clean" surface are suitable for the production of nanocrystalline materials.
  • the chemical processes primarily involve the thermal decomposition of solid or gaseous compounds and the reduction of solid substances or metal ions in solutions.
  • a major disadvantage of many chemical manufacturing processes is that the free surface of the crystallites is covered with foreign atoms or molecules.
  • the problem is solved for powder mixtures which tend to set amorphous structural components in their composition, surprisingly by mechanical stressing of at least 12 g of commercial starting powder between 2 and 250 ⁇ m over a long period of time under a neutral or reducing atmosphere at room temperature.
  • the duration for the production of the secondary powder according to the invention is determined according to transmission electromicroscopic recordings (TEM).
  • TEM transmission electromicroscopic recordings
  • the state according to the invention for the secondary powder particles is only reached when these images only show crystallites ⁇ 10 mm. Strong heating must be avoided during the grinding process, since otherwise the metastable amorphous phase will not be preserved. On the other hand, the grinding process must not be too slow, since then no nanocrystalline structure will be formed.
  • a composition of the secondary powder is particularly advantageous in which, according to the corresponding metastable phase diagram at a suitable temperature, there is a multiphase region between the amorphous and the crystalline phase.
  • These secondary powder particles can be processed under the conditions of the surrounding atmosphere without special precautions.
  • the material made from these secondary powder particles compacted by known methods shows a nanocrystalline structure.
  • the method is suitable according to claim 1 for starting powder from metallic materials, from materials with a metal character and from ceramic materials with multiple components.
  • Binary or multiphase substances consisting of at least one element from the group Y, Ti, Zr, Hf, Mo, Nb, Ta, W and at least one element from the group V, Cr, Mn, Fe, Co, Ni, Cu, are particularly advantageous.
  • Pd without or with the addition of accompanying elements such as Si, Ge, B and / or oxides, nitrides, borides, carbides and their possible mixed crystals exist either in pure form or as corresponding master alloys of these groups.
  • the extreme degrees of deformation can be particularly advantageous by high energy milling e.g. can be achieved by impact grinding, particularly in an attritor.
  • the specific surface area of the secondary powder particles produced according to the invention does not increase with the milling time, but remains the same or decreases slightly, that is to say that the seal is gas-tight and that there are no internal surfaces in the region of the nanocrystalline structural components which are accessible to the gases of the surrounding atmosphere .
  • the surfaces in the nanocrystalline area remain clean, the chemical resistance is surprisingly high, since the small crystallites are embedded in an amorphous phase.
  • the object of the invention is illustrated using the example of a titanium-nickel powder mixture as the starting material.
  • the powder mixture consists of 70% by weight of commercially available Ti powder (FSSS 28 ⁇ m) and 30% by weight of commercially available nickel powder (FSSS 4.7 ⁇ m).
  • the Powders are first mixed in an (Turbula) mixer for one hour and then ground in a horizontally located attritor.
  • the powder batch weight is 1000 g.
  • the grinding takes place using rolling bearing balls with a diameter of approx. 6 mm.
  • the mass ratio of balls to powder is 20: 1.
  • the grinding time is 90 hours with a stirrer arm rotation of 200 rpm.
  • the grinding times can be significantly reduced by using larger grinding units (batch load 10 kg).
  • Fig. 1 and 2 show TEM images with a magnification of 200,000: 1 of Ti Ni secondary powder with 70/30 mass%.
  • the crystallites embedded in an amorphous phase are clearly visible on the images.
  • Fig. 1 shows the grinding result after 40 hours of grinding. Although the amorphous phase is already present here, some of the crystallites are still> 10 nm in size. At 90 hours milling time (Fig. 2), only crystallites ⁇ 10 nm can be seen.
  • the measurement of the specific surface of a Ti Ni powder with 70/30 mass% according to the BET method shows the following values: 0.152 m2 / g (0 h), 0.140 m2 / g (90 h), 0.137 m2 / g (180 h) .
  • the specific surface surprisingly decreases slightly with the grinding time.
  • Figures 3a to 3c show the results of tests in which 50 mg of the Ti Ni powder with 70/30 mass% in a 1 NHNo3 solution at 30 ° C (Fig. 3a), at 40 ° C (Fig. 3b) and at 50 ° C (Fig. 3c) were introduced.
  • the detached amount of Ni as a function of time is shown for powders with different grinding times were obtained.
  • the powders were first mixed in a Turbula mixer for 1 h and then ground in an attritor for 0 h - 180 h. It can be clearly seen that the detached amount of Ni becomes much smaller with longer grinding times. After 36 hours of grinding, the secondary powder shows significantly higher chemical resistance than the untreated starting powder mixture.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Powder Metallurgy (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)

Abstract

Es wird ein Verfahren zur Herstellung eines Sekundärpulvers mit nanokristalliner Struktur und versiegelter Teilchenoberfläche aus Pulvern von mindestens zwei Werkstoffen der Gruppe der Metalle, der Verbindungen mit Metallcharakter und der keramischen Werkstoffe, in einer Zusammensetzung, die zur Einstellung amorpher Gefügeanteile neigen beschrieben. Die Ausgangspulver werden einer hohen Beanspruchung von mindestens 12 g ausgesetzt, bis in der elektronenmikroskopischen Durchstrahlung nur noch Kristallite < 10 nm nachzuweisen sind.A process is described for the production of a secondary powder with a nanocrystalline structure and a sealed particle surface from powders of at least two materials from the group of metals, the compounds of metal character and the ceramic materials, in a composition which tends to set amorphous structural components. The starting powders are subjected to a high stress of at least 12 g until only crystallites <10 nm can be detected in the electron microscopic radiation.

Description

Die Erzeugung von Werkstoffen mit nanokristalliner Struktur kann so erfolgen, daß Kristalle mit einem Durchmesser von einigen Nanometern unter hohem Druck (einige MPa) zu einem Festkörper kompaktiert werden. Prinzipiell eignen sich also alle Methoden, die die Herstellung von hinreichend kleinen Kristallen mit "sauberer" Oberfläche ermöglichen, zur Produktion von nanokristallinen Materialien.Materials with a nanocrystalline structure can be produced in such a way that crystals with a diameter of a few nanometers are compacted into a solid under high pressure (a few MPa). In principle, all methods that enable the production of sufficiently small crystals with a "clean" surface are suitable for the production of nanocrystalline materials.

Grundsätzlich lassen sich bei der Herstellung kleiner Kristallite chemische und physikalische Methoden unterscheiden.Basically, chemical and physical methods can be distinguished in the manufacture of small crystallites.

Bei den chemischen Verfahren handelt es sich vorrangig um die thermische Zersetzung fester bzw. gasförmiger Verbindungen sowie um die Reduktion fester Substanzen bzw. von Metallionen in Lösungen. Ein wesentlicher Nachteil vieler chemischer Herstellungsverfahren ist die Belegung der freien Oberfläche der Kristallite mit Fremdatomen bzw. Molekülen.The chemical processes primarily involve the thermal decomposition of solid or gaseous compounds and the reduction of solid substances or metal ions in solutions. A major disadvantage of many chemical manufacturing processes is that the free surface of the crystallites is covered with foreign atoms or molecules.

Zu den bekannten physikalischen Methoden, die für die Herstellung kleiner Kristalle am häufigsten benutzt werden, zählen Zerstäuben im elektrischen Lichtbogen und Verdampfen in einer inerten Atmosphäre bzw. im Vakuum mit nachfolgender isoentroper Entspannung. Diese Verfahren haben den Vorteil, daß die Oberfläche des erhaltenen einzelnen Kristallpulverteilchens - bei geeigneter Versuchsführung - praktisch frei von Fremdstoffen gehalten werden kann, und daß das Pulver direkt zu Formkörpern mit nanokristalliner Struktur kompaktierbar ist. Da zur Erzeugung von beispielsweise einer Monolage Sauerstoff auf der freien Oberfläche von 1 g Eisenkristalliten mit einem Durchmesser von 5 nm nur ca. 0,1 g Sauerstoff erforderlich sind und dies ca. 10¹⁰ mal mehr Sauerstoff ist als typischerweise im Restgas eines Vakuumrezipieten enthalten ist, dauert es nicht lange bis sich auf der hohen spezifischen Oberfläche der hier beispielhaft angeführten Eisenpartikel im Nanometer-Bereich relativ große Mengen von unerwünschtem Sauerstoff, Stickstoff oder/und Wassermolekülen angelagert haben, um dort beispielsweise Oxid-, Nitrid- oder/und Oxinitrid-Beläge auszubilden. Die Vermeidung der Verunreinigung der Oberflächen ist auch hier das größte Problem. Die Herstellung von sauberen Werkstoffen mit nanokristalliner Struktur ist also sehr aufwendig.Known physical methods that are used most frequently for the production of small crystals include atomization in an electric arc and evaporation in an inert atmosphere or in a vacuum followed by isoentropic Relaxation. These processes have the advantage that the surface of the individual crystal powder particle obtained can be kept practically free of foreign substances with a suitable test procedure, and that the powder can be compacted directly into shaped bodies with a nanocrystalline structure. Since only about 0.1 g of oxygen is required to generate, for example, a monolayer of oxygen on the free surface of 1 g of iron crystallites with a diameter of 5 nm and this is about 10¹⁰ times more oxygen than is typically contained in the residual gas of a vacuum recipient, it does not take long for relatively large amounts of undesirable oxygen, nitrogen and / or water molecules to have accumulated on the high specific surface area of the iron particles exemplified here, in order to form oxide, nitride or / and oxynitride deposits there, for example . Avoiding contamination of the surfaces is also the biggest problem here. The production of clean materials with a nanocrystalline structure is therefore very complex.

Es ist daher Aufgabe der vorliegenden Erfindung, diesen großen Nachteil in der Herstellung nanokristalliner Werkstoffe zu umgehen, dadurch daß man Sekundärpulverteilchen im Bereich von einigen µm mit nanokristalliner Struktur erzeugt, die auf ihrer äußeren Oberfläche gasdicht gegenüber den möglichen Komponenten des Umgebungsmediums versiegelt sind und somit unter den üblichen Bedingungen einer pulvermetallurgischen Fertigung problemlos zu Formkörpern mit nanokristalliner Struktur verarbeitbar sind.It is therefore an object of the present invention to circumvent this major disadvantage in the production of nanocrystalline materials by producing secondary powder particles in the range of a few microns with a nanocrystalline structure, which are sealed gas-tight on their outer surface to the possible components of the surrounding medium and thus below the usual conditions of powder metallurgy production can be easily processed into moldings with a nanocrystalline structure.

Die Lösung der Aufgabe gelingt für Pulvermischungen, die in ihrer Zusammensetzung zur Einstellung amorpher Gefügeanteile neigen, überraschenderweise durch mechanische Beanspruchung von mindestens 12 g handelsüblicher Ausgangspulver zwischen 2 und 250 µm über längere Zeit unter neutraler bzw. reduzierender Atmosphäre bei Raumtemperatur. Die Dauer zur Herstellung des erfindungsgemäßen Sekundärpulvers wird bestimmt nach transmissions-elektromikroskopischen Aufnahmen (TEM). Erst wenn diese Aufnahmen nur Kristallite < 10 mm ausweisen, ist der erfindungsgemäße Zustand für die Sekundärpulverteilchen erreicht. Beim Mahlvorgang muß eine starke Erwärmung vermieden werden, da sonst die metastabile amorphe Phase nicht erhalten bleibt, andererseits darf der Mahlvorgang auch nicht zu langsam ablaufen, da sich dann keine nanokristalline Struktur ausbildet.The problem is solved for powder mixtures which tend to set amorphous structural components in their composition, surprisingly by mechanical stressing of at least 12 g of commercial starting powder between 2 and 250 μm over a long period of time under a neutral or reducing atmosphere at room temperature. The duration for the production of the secondary powder according to the invention is determined according to transmission electromicroscopic recordings (TEM). The state according to the invention for the secondary powder particles is only reached when these images only show crystallites <10 mm. Strong heating must be avoided during the grinding process, since otherwise the metastable amorphous phase will not be preserved. On the other hand, the grinding process must not be too slow, since then no nanocrystalline structure will be formed.

Besonders vorteilhaft ist eine Zusammensetzung des Sekundärpulvers, bei der nach dem entsprechenden metastabilen Phasendiagramm bei geeigneter Temperatur ein Mehrphasengebiet zwischen amorpher und kristalliner Phase vorliegt.A composition of the secondary powder is particularly advantageous in which, according to the corresponding metastable phase diagram at a suitable temperature, there is a multiphase region between the amorphous and the crystalline phase.

Diese Sekundärpulverteilchen können unter den Bedingungen der umgebenden Atmosphäre ohne besondere Vorsichtsmaßnahmen weiterverarbeitet werden. Das nach bekannten Methoden kompaktierte Material aus diesen Sekundärpulverteilchen zeigt nanokristalline Struktur.These secondary powder particles can be processed under the conditions of the surrounding atmosphere without special precautions. The material made from these secondary powder particles compacted by known methods shows a nanocrystalline structure.

Das Verfahren eignet sich entsprechend Anspruch 1 für Ausgangspulver aus metallischen Werkstoffen, aus Werkstoffen mit Metallcharakter und aus keramischen Werkstoffen mit mehreren Komponenten. Besonders vorteilhaft sind binäre oder mehrphasige Stoffe, die aus mindestens einem Element der Gruppe Y, Ti,Zr, Hf,Mo, Nb, Ta, W und mindestens einem Element der Gruppe V, Cr, Mn, Fe, Co, Ni, Cu, Pd ohne oder unter Hinzufügung von Begleitelementen wie Si, Ge, B und/oder Oxiden, Nitriden, Boriden, Carbiden sowie aus deren möglichen Mischkristallen bestehen entweder in reiner Form oder als entsprechende Vorlegierungen dieser Gruppen.The method is suitable according to claim 1 for starting powder from metallic materials, from materials with a metal character and from ceramic materials with multiple components. Binary or multiphase substances consisting of at least one element from the group Y, Ti, Zr, Hf, Mo, Nb, Ta, W and at least one element from the group V, Cr, Mn, Fe, Co, Ni, Cu, are particularly advantageous. Pd without or with the addition of accompanying elements such as Si, Ge, B and / or oxides, nitrides, borides, carbides and their possible mixed crystals exist either in pure form or as corresponding master alloys of these groups.

Die extremen Verformungsgrade können besonders vorteilhaft durch Hochenergiemahlen z.B. durch Impact-Grinding insbesondere in einem Attritor erreicht werden.The extreme degrees of deformation can be particularly advantageous by high energy milling e.g. can be achieved by impact grinding, particularly in an attritor.

Oberraschenderweise nimmt die spezifische Oberfläche der erfindungsgemäß hergestellten Sekundärpulverteilchen mit der Mahldauer nicht zu, sondern bleibt gleich oder nimmt geringfügig ab, d.h., daß die Versiegelung gasdicht ist und daß keine inneren Oberflächen im Bereich der nanokristallinen Gefügeanteile vorliegen, die den Gasen der umgebenden Atmosphäre zugänglich sind. Die Oberflächen im nanokristallinen Bereich bleiben sauber, die chemische Resistenz ist überraschend hoch, da die kleinen Kristallite in einer amorphen Phase eingebettet sind.Surprisingly, the specific surface area of the secondary powder particles produced according to the invention does not increase with the milling time, but remains the same or decreases slightly, that is to say that the seal is gas-tight and that there are no internal surfaces in the region of the nanocrystalline structural components which are accessible to the gases of the surrounding atmosphere . The surfaces in the nanocrystalline area remain clean, the chemical resistance is surprisingly high, since the small crystallites are embedded in an amorphous phase.

Der Gegenstand der Erfindung wird am Beispiel einer Titan-Nickel-Pulvermischung als Ausgangsmaterial dargestellt.The object of the invention is illustrated using the example of a titanium-nickel powder mixture as the starting material.

Die Pulvermischung besteht aus 70 Gew.-% handsüblichen Ti-Pulver (FSSS 28 µm) und 30 Gew.-% handelsüblichen Nickelpulver (FSSS 4,7 µm). Die Pulver werden zunächst eine Stunde in einem (Turbula)-Mischer gemischt und dann in einem horizontal liegenden Attritor gemahlen. Das Pulverchargengewicht beträgt 1000 g. Die Mahlung erfolgt unter Verwendung von Wälzlagerkugeln mit einem Durchmesser von ca. 6 mm. Das Massenverhältnis Kugeln zu Pulver beträgt 20:1. Die Mahldauer beträgt 90 Stunden bei einer Rührarmdrehung von 200 U/min. Durch Einsatz größerer Mahlaggregate (Chargeneinsatz 10 kg) können die Mahldauern signifikant abgesenkt werden.The powder mixture consists of 70% by weight of commercially available Ti powder (FSSS 28 µm) and 30% by weight of commercially available nickel powder (FSSS 4.7 µm). The Powders are first mixed in an (Turbula) mixer for one hour and then ground in a horizontally located attritor. The powder batch weight is 1000 g. The grinding takes place using rolling bearing balls with a diameter of approx. 6 mm. The mass ratio of balls to powder is 20: 1. The grinding time is 90 hours with a stirrer arm rotation of 200 rpm. The grinding times can be significantly reduced by using larger grinding units (batch load 10 kg).

Fig. 1 und Fig. 2 zeigen TEM-Aufnahmen mit einer Vergrößerung von 200.000:1 von Ti Ni Sekundärpulver mit 70/30 Massen %. Auf den Aufnahmen sind deutlich die Kristallite eingebettet in einer amorphen Phase zu erkennen. Fig. 1 zeigt das Mahlergebnis nach 40 Stunden Mahldauer. Hier ist zwar die amorphe Phase bereits vorhanden, die Kristallite haben jedoch teilweise noch eine Größe > 10 nm. Bei 90 Stunden Mahldauer (Fig. 2) sieht man nur Kristallite < 10 nm.1 and 2 show TEM images with a magnification of 200,000: 1 of Ti Ni secondary powder with 70/30 mass%. The crystallites embedded in an amorphous phase are clearly visible on the images. Fig. 1 shows the grinding result after 40 hours of grinding. Although the amorphous phase is already present here, some of the crystallites are still> 10 nm in size. At 90 hours milling time (Fig. 2), only crystallites <10 nm can be seen.

Die Messung der spezifischen Oberfläche eines Ti Ni Pulvers mit 70/30 Massen % nach dem BET-Verfahren zeigt folgende Werte: 0,152 m²/g (0 h), 0,140 m²/g (90 h), 0,137 m²/g (180 h). Die spezifische Oberfläche nimmt also überraschenderweise mit der Mahldauer geringfügig ab.The measurement of the specific surface of a Ti Ni powder with 70/30 mass% according to the BET method shows the following values: 0.152 m² / g (0 h), 0.140 m² / g (90 h), 0.137 m² / g (180 h) . The specific surface surprisingly decreases slightly with the grinding time.

Die Bilder 3a bis 3c zeigen die Ergebnisse von Versuchen, bei denen jeweils 50 mg des Ti Ni-Pulvers mit 70/30 Massen % in eine 1 NHNo₃-Lösung bei 30 °C (Fig. 3a), bei 40 °C (Fig. 3b) und bei 50 °C (Fig. 3c) eingebracht wurden. Dargestellt ist die abgelöste Ni-Menge in Abhängigkeit von der Zeit, für Pulver, die mit unterschiedlicher Mahldauer gewonnen wurden. Die Pulver wurden jeweils zunächst 1 h im Turbula Mischer gemischt und danach 0 h - 180 h im Attritor gemahlen. Es ist deutlich zu erkennen, daß bei längerer Mahldauer die abgelöste Ni-Menge wesentlich geringer wird. Das Sekundärpulver zeigt bereits nach 36 Stunden Mahldauer erheblich höhere chemische Resistenz als die unbehandelte Ausgangspulvermischung.Figures 3a to 3c show the results of tests in which 50 mg of the Ti Ni powder with 70/30 mass% in a 1 NHNo₃ solution at 30 ° C (Fig. 3a), at 40 ° C (Fig. 3b) and at 50 ° C (Fig. 3c) were introduced. The detached amount of Ni as a function of time is shown for powders with different grinding times were obtained. The powders were first mixed in a Turbula mixer for 1 h and then ground in an attritor for 0 h - 180 h. It can be clearly seen that the detached amount of Ni becomes much smaller with longer grinding times. After 36 hours of grinding, the secondary powder shows significantly higher chemical resistance than the untreated starting powder mixture.

Claims (15)

1. Verfahren zur Herstellung von Sekundärpulverteilchen mit nanokristalliner Struktur und mit versiegelter Teilchenoberfläche aus Pulvern von mindestens zwei Werkstoffen der Gruppen der Metalle, der Verbindungen mit Metallcharakter und der keramischen Werkstoffe, in einer Zusammensetzung, die zur Einstellung amorpher Gefügeanteile neigt, dadurch gekennzeichnet, daß die Pulver gemischt und solange einer hohen Beanspruchung von mindestens 12 g ausgesetzt werden, bis in der elektronenmikroskopischen Durchstrahlung nur noch Kristallite < 10 nm nachzuweisen sind.1. A process for the preparation of secondary powder particles with a nanocrystalline structure and with a sealed particle surface from powders of at least two materials from the groups of metals, the compounds of metal character and the ceramic materials, in a composition which tends to set amorphous structural components, characterized in that the Powder mixed and exposed to a high load of at least 12 g until only crystallites <10 nm can be detected in the electron microscope. 2. Verfahren zur Herstellung von Sekundärpulverteilchen mit nanokristalliner Struktur und mit versiegelter Teilchenoberfläche aus binären oder mehrphasigen Stoffen, die aus mindestens einem der Elemente Y, Ti, Zr, Hf, Nb, Mo, Ta und W mit mindestens einem der Elemente V, Cr, Mn, Fe, Co, Ni, Cu und Pd, bestehen in einer Zusammensetzung, die zur Einstellung amorpher Gefügeanteile neigt, dadurch gekennzeichnet, daß die ausgewählten Elemente in reiner Form oder als Vorlegierungen als Pulver gemischt und solange einer hohen mechanischen Beanspruchung von mindestens 12 g ausgesetzt werden, bis in der elektronenmikroskopischen Durchstrahlung nur noch Kristallite < 10 nm nachzuweisen sind.2. Process for the production of secondary powder particles with a nanocrystalline structure and with a sealed particle surface made of binary or multiphase substances which consist of at least one of the elements Y, Ti, Zr, Hf, Nb, Mo, Ta and W with at least one of the elements V, Cr, Mn, Fe, Co, Ni, Cu and Pd consist of a composition that tends to set amorphous structure components, characterized in that the selected elements are mixed in pure form or as master alloys as a powder and as long as a high mechanical stress of at least 12 g exposed until only crystallites <10 nm can be detected in the electron microscopic radiation. 3. Verfahren zur Herstellung von Sekundärpulverteilchen mit nanokristalliner Struktur und mit versiegelter Teilchenoberfläche aus binären oder mehrphhasigen Stoffen, die aus mindestens einem der Elemente Y, Ti, Zr, Hf, Nb, Mo, Ta und W mit mindestens einem der Elemente V, Cr, Mn, Fe, Co, Ni, Cu und Pd, und mindestens einem Begleitelement wie Si, Ge, B oder Oxiden, Nitriden, Boriden, Carbiden, sowie deren möglichen Mischkristallen bestehen in einer Zusammensetzung, die zur Einstellung amorpher Gefügeanteile neigt, dadurch gekennzeichnet, daß die ausgewählten Bestandteile in reiner Form oder als Vorlegierungen als Pulver gemischt und solange einer hohen mechanischen Beanspruchung von mindestens 12 g ausgesetzt werden, bis in der elektronenmikroskopischen Durchstrahlung nur noch Kristallite < 10 nm nachzuweisen sind.3. Process for the production of secondary powder particles with a nanocrystalline structure and with a sealed particle surface made of binary or multiphase substances which consist of at least one of the elements Y, Ti, Zr, Hf, Nb, Mo, Ta and W with at least one of the elements V, Cr, Mn, Fe, Co, Ni, Cu and Pd, and at least one accompanying element such as Si, Ge, B or oxides, nitrides, borides, carbides, and their possible mixed crystals consist of a composition that tends to set amorphous structural components, characterized in that that the selected constituents are mixed in pure form or as master alloys as powders and are exposed to high mechanical stress of at least 12 g until only crystallites <10 nm can be detected in the electron microscopic radiation. 4. Verfahren zur Herstellung von Sekundärpulverteilchen mit nanokristalliner Struktur und mit versiegelter Teilchenoberfläche aus binären oder mehrphasigen Stoffen, die aus mindestens einem der Elemente Y, Ti, Zr, Hf, Nb, Mo, Ta und W mit mindestens einem der Elemente V, Cr, Mn, Fe, Co, Ni, Cu und Pd, und mindestens einem Begleitelement wie Si, Ge, B und Oxiden, Nitriden, Boriden, Carbiden, sowie deren möglichen Mischkristallen bestehen, in einer Zusammensetzung, die zur Einstellung amorpher Gefügeanteile neigt, dadurch gekennzeichnet, daß die Bestandteile in reiner Form oder als Vorlegierungen als Pulver gemischt und solange einer hohen mechanischen Beanspruchung von mindestens 12 g ausgesetzt werden, bis in der elektronenmikroskopischen Durchstrahlung nur noch Kristallite < 10 nm nachzuweisen sind.4. Process for the production of secondary powder particles with a nanocrystalline structure and with a sealed particle surface made of binary or multiphase substances which consist of at least one of the elements Y, Ti, Zr, Hf, Nb, Mo, Ta and W with at least one of the elements V, Cr, Mn, Fe, Co, Ni, Cu and Pd, and at least one accompanying element such as Si, Ge, B and oxides, nitrides, borides, carbides, and their possible mixed crystals, in a composition that tends to set amorphous structural components, characterized that the constituents are mixed in pure form or as master alloys as a powder and are exposed to high mechanical stress of at least 12 g until in the electron microscopic Radiography only crystallites <10 nm can be detected. 5. Verfahren nach den Ansprüchen 1 bis 4, dadurch gekennzeichnet, daß die Zusammensetzung des Sekundärpulvers so gewählt ist, daß nach dem entsprechenden metastabilen Phasendiagramm bei dieser Zusammensetzung bei geeigneter Temperatur ein Mehrphasengebiet zwischen amorpher und kristalliner Phase vorliegt.5. The method according to claims 1 to 4, characterized in that the composition of the secondary powder is selected so that, according to the corresponding metastable phase diagram at this composition at a suitable temperature, there is a multi-phase region between the amorphous and crystalline phase. 6. Verfahren nach den Ansprüchen 1 bis 4, dadurch gekennzeichnet, daß die hohe mechanische Beanspruchung durch Kaltverformen erfolgt.6. The method according to claims 1 to 4, characterized in that the high mechanical stress takes place by cold working. 7. Verfahren nach den Ansprüchen 1 bis 4, dadurch gekennzeichnet, daß die hohe mechanische Beanspruchung durch Hochenergiemahlen, z.B. Impact-Grinding, bewirkt wird.7. The method according to claims 1 to 4, characterized in that the high mechanical stress caused by high energy milling, e.g. Impact grinding. 8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß zum Hochenergiemahlen ein Attritor verwendet wird.8. The method according to claim 7, characterized in that an attritor is used for high energy grinding. 9. Sekundärpulver mit einem Gefüge nanokristalliner Struktur und versiegelten Teilchenoberflächen, erhältlich nach dem Verfahrensanspruch 1.9. Secondary powder with a structure of nanocrystalline structure and sealed particle surfaces, obtainable according to process claim 1. 10. Sekundärpulver mit einem Gefüge nanokristalliner Struktur und versiegelten Teilchenoberflächen, erhältlich nach dem Verfahrensanspruch 2.10. Secondary powder with a structure of nanocrystalline structure and sealed particle surfaces, obtainable according to process claim 2. 11. Sekundärpulver mit einem Gefüge nanokristalliner Struktur und versiegelten Teilchenoberflächen, erhältlich nach dem Verfahrensanspruch 3.11. Secondary powder with a structure of nanocrystalline structure and sealed particle surfaces, obtainable according to process claim 3. 12. Sekundärpulver mit einem Gefüge nanokristalliner Struktur und versiegelten Teilchenoberflächen, erhältlich nach dem Verfahrensanspruch 4.12. Secondary powder with a structure of nanocrystalline structure and sealed particle surfaces, obtainable according to process claim 4. 13. Sekundärpulver mit einem Gefüge nanokristalliner Struktur und versiegelten Teilchenoberflächen, erhältlich nach dem Verfahrensanspruch 5.13. Secondary powder with a structure of nanocrystalline structure and sealed particle surfaces, obtainable according to process claim 5. 14. Sekundärpulver mit einem Gefüge nanokristalliner Struktur und versiegelten Teilchenoberflächen nach den Ansprüchen 9 bis 13, dadurch gekennzeichnet, daß das Legierungssystem der Bestandteile eine ausgeprägte eutektische bzw. eutektoide Reaktion zeigt, und daß das Mischungsverhältnis so gewählt ist, daß es außerhalb der Randlöslichkeiten liegt.14. Secondary powder with a structure of nanocrystalline structure and sealed particle surfaces according to claims 9 to 13, characterized in that the alloy system of the components shows a pronounced eutectic or eutectoid reaction, and that the mixing ratio is chosen so that it is outside the marginal solubilities. 15. Formkörper mit einem Gefüge nanokristalliner Struktur erhältlich aus einem Sekundärpulver nach den Ansprüchen 9 bis 14 durch Verdichten des Sekundärpulvers bei einer deutlich unterhalb der Rekristallisationstemperatur liegenden Temperatur.15. Shaped body with a structure of nanocrystalline structure obtainable from a secondary powder according to claims 9 to 14 by compacting the secondary powder at a temperature significantly below the recrystallization temperature.
EP88119570A 1987-12-04 1988-11-24 Process for preparing secondary powder particles with a nanocrystalline structure and with a closed surface Expired - Lifetime EP0319786B1 (en)

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