Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/10—Alloys containing non-metals
  • C22C1/1036—Alloys containing non-metals starting from a melt
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D19/00—Casting in, on, or around objects which form part of the product
  • B22D19/14—Casting in, on, or around objects which form part of the product the objects being filamentary or particulate in form
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/10—Alloys containing non-metals
  • C22C1/1036—Alloys containing non-metals starting from a melt
  • C22C1/1047—Alloys containing non-metals starting from a melt by mixing and casting liquid metal matrix composites
• • 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

Definitions

• the invention relates to a method for producing particle-reinforced metals according to the preamble of claim 1.
• nanoscale ceramic reinforcing particles are introduced into a molten aluminum alloy and dispersed in the melt with a stirrer.
• agglomerates i. an aggregation of particles
• the reason for the occurrence of particle agglomerates are, on the one hand, especially in the case of nanoparticles, the high interfacial forces, which lead to the particles being present as agglomerates even before they are processed.
• the low energy that acts on the agglomerates through the mixing processes in the melt is usually insufficient to separate the agglomerates during the process.
• the poor wetting of the ceramic particles with the molten metal prevents effective breakage of the agglomerates.
• Increasing the strength of castings by introducing nanoparticles has a very high potential for increasing the room temperature resistance, the high-temperature strength and creep resistance.
• the ductility is much less reduced by nanoparticles than by microparticles or reinforcing fibers.
• the objective is to disperse nanoparticles with a particle size of a few nanometers finely in the cast component so that there is the ideal free distance between the particles for dislocations, which depends inter alia on the respective alloy, but generally between 20 nm and 200 nm.
• the reinforcing particles hinder the migration of dislocations in the metal occurring at voltages applied from the outside and thus increase the resistance to plastic deformation of the component. Too high a proportion of the reinforcing particles, however, leads to a brittle material.
• the agglomerates For effective dispersion hardening in nanoparticle-reinforced composite materials produced by casting, the agglomerates must thus be separated into their individual particles.
• a homogeneous distribution of the particles in the metal has a positive effect on the material properties.
• the ductility, the creep behavior and the wear properties are positively influenced by a homogeneous material structure.
• the object of the invention is therefore to achieve the most homogeneous possible distribution of nano- or micro-scale reinforcing particles in the molten metal.
• a mixture of the reinforcing particles and particles is prepared, which are soluble in the molten metal. This mixture is then introduced into the molten metal. In the molten metal, the soluble particles are dissolved, whereby the reinforcing particles are separated. In an agglomerate of reinforcing particles and soluble particles in the mixture, the soluble particles form as it were placeholders, which disappear by dissolution in the melt, whereby the isolated reinforcing particles remain.
• the soluble particles dissolve, it may also be due to a chemical reaction.
• silica particles can be used as soluble particles. The silica may then react with the metal components of the alloy, for example metal oxides and metal silicides. The energy for separating the particles can thus also come from the chemical energy of reactions that take place in the molten metal.
• the reinforcing particles may also be made in situ, for example, from particles which are melt-oxidized to form reinforcing particles of a refractory oxide. That is, according to the present invention, a mixture consisting of particles soluble in the molten metal and particles forming reinforcing particles in the molten metal may also be introduced into the molten metal.
• the scattered reinforcing particles are distributed mechanically homogeneously in the melt.
• a stirrer, an extruder or another mixing device can be used.
• the mechanical energy that must be applied in the melt for separating the agglomerates, is low according to the invention.
• Microscale particles ie particles having an average particle size of from 1 ⁇ m to 1000 ⁇ m, or nanoscale particles, ie particles having an average particle size of from 1 nm to 1 ⁇ m, are preferably used both as reinforcing particles and as soluble particles, preferably from 100 nm to less than 1 microns.
• the mean particle size of the soluble particles and the reinforcing particles is preferably of the same order of magnitude.
• the ratio of the average particle size of the soluble particles to the average particle size of the reinforcing particles may be between 10: 1 and 1:10.
• the volume fraction of the reinforcing particles in the metal in the case of nanoscale reinforcing particles is preferably 0.1% to 10%, in particular 1% to 10%, in the case of microscale particles 2% to 30%, in particular 5% to 20%.
• the reinforcing particles in the melt are preferably insoluble.
• the reinforcing particles can therefore behave inertly in the molten metal. If they partially dissolve, this may be due to a chemical reaction at the interface. In this case, the kinetics of the reaction must be such that possible reactions with the reinforcing particles proceed much slower than with the soluble particles.
• ceramic particles are used as reinforcing particles, for example carbides, such as silicon carbide (SiC) or metal oxides, such as aluminum oxide, as well as mixtures of these compounds.
• the soluble particles may consist of metals or ceramics.
• silicon dioxide is suitable for magnesium alloys.
• mixtures of particles soluble in the molten metal and reinforcing particles and / or particles which form reinforcing particles in the molten metal arise as a by-product in other processing processes, for example in flame spraying.
• Such mixtures can be used particularly economically according to the invention.
• flame spraying for example, a particle mixture of aluminum, aluminum oxide and silicon dioxide particles, which can be used according to the invention, is frequently produced.
• the inventive method is particularly suitable for the production of particle-reinforced light metals, in particular for the production of cast components of aluminum or magnesium alloys.
• Such cast components can be used as an engine component, such as crankcase or engine support block, as chassis parts but also, for example, as a dashboard.
• a melt of a MgAl6Sr2 alloy is mixed with a mixture of Al 2 O 3 particles and SiO 2 particles in a volume ratio of 1: 5, which is uniformly distributed in the melt by stirring.
• the particle size of both particles is 20 nm to 50 nm.
• the amount of the mixture is 10 wt .-%, based on the melt.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Composite Materials (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)

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• 2006
  • 2006-01-18 DE DE102006002337A patent/DE102006002337A1/de active Pending
  • 2006-12-04 EP EP06025036.2A patent/EP1811049B1/fr active Active

Patent Citations (5)

Non-Patent Citations (3)

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