DE2010841A1 - Magnesium alloys and fiber materials as well as metal ceramics made from them - Google Patents

Description

Dr.phil.W.Dannöhl 5.3.197o ^. V ,? T _n

Dr.Da / Kst. f

Magnesium alloys and fiber materials as well as from them manufactured metal ceramics.

The invention relates to novel high-strength and heat-resistant magnesium alloys, in particular those with a fiber structure and ceramic fibers and metal ceramics made therefrom.

As heat-resistant magnesium alloys, those with cerium and thorium contents are known, which are usually grain-refined by zirconium, but their applicability ends at around J2o G. Their tensile strength values are between 2o ° 0

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14 and 28 kp / mm, their densities between 1.77 and 1.83 g / cm In the manufacture of such materials from powder mixtures from a Mg-Zr alloy on the one hand and from aluminum or an Al-Mg alloy, on the other hand, are tensile strength values

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of 36.5 kp / mm and a yield strength of 31 kp / mm with an elongation of 8% , recently further improvements through yttrium and finally scandium additives, which, however, have a strong effect on cost increases »For applications such as highly stressed components in flight and vehicle construction and engine parts, the aforementioned materials have been used with preference because of their low weight and the relatively favorable ratio of strength to weight and because of their good machinability. However, there is still a desire to increase the strength values and the area of application at elevated temperatures. Numerous attempts at alloy development have only continued to a limited extent here, since larger alloy additions always resulted in an impairment of the toughness properties due to the occurrence of brittle intermetallic phases.

In contrast, the subject matter of the invention is a for Magneaiuai base materials broke new ground, the addition

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a body-centered cubic, which in turn is easily deformable intermetallic phase of the NiTi type, more generally, the so-called. AB type with CsCl structure and lattice constants between 2.60 and 3.2o A in parts by weight of 5% up to 97%, preferably up to 65%, which in the solid state is only insignificant is soluble in the hexagonal magnesium lattice.

The properties of this CsCl structure phase are in the course of the last decade in a number of characteristic compositions, especially the binary NiTi alloys with contents between 54 and 60 percent by weight nickel and other soluble or insoluble alloy additives, but also, for example, the mixed crystal series NiTi-PeTi, has been studied in detail. The former in particular have found considerable interest and application under the name "Nitinol" as wear-resistant and corrosion-resistant, highly damping and "memory" alloys. Thus, 55-Nitinol in the annealed condition Zugfestigkeitswe te _r of 88 kgf / mm at 17

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kp / mm yield point, a total elongation of 60% and a constriction of 2o%, after cold deformation a tensile strength of up to 175 kp / mm2 at up to 133 kp / mm2 yield point and a minimum elongation of 12%. The 60-nitinol alloy can be obtained with hardness values between 3o and 62 Rc. The density values of this phase are between 6.45 and 7.1.

The compilation of these strength properties already shows the extent to which the additive is used This phase is suitable according to the mixing rule, the strength and hardness of the technically common starting materials on a magnesium basis while improving the deformation properties. It rises through it also the density depending on the composition, e.g. at Io vol.% corresponding to 29% by weight of alloy additive to 2.2 g / cm 2o vol.% Corresponding to 48 wt.% Alloy addition to 2.68 g / cm, i.e. in the latter case to the density of technical

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see aluminum alloys. However, the specific strength, the strength-to-weight ratio, which "is to be used as a basis for design considerations" increases much more rapidly. 4% by weight lithium and 10% by volume NiTi corresponding to 17.9% by weight nickel and 14-7% by weight titanium to 1.97 g / cm ³ .

An alloy of 50% by volume magnesium, 40% by volume lithium and Io% by volume of the NiTi phase, i.e. from 5 °, 4% by weight magnesium, 12.3% by weight lithium, 20.5% by weight nickel and 16.8% by weight titanium even only has a density of 1.73 g / cm *, i.e. about corresponding to the density of pure magnesium, and moreover consists of a phase mixture of only two space-centered cubes Phases, since instead of the hexagonal magnesium with the addition of more than about 10% by weight of lithium the body-centered cubic lattice of lithium occurs and thereby further improves deformability will. - This makes the density value of 2.11 g / cnr for glass fiber reinforced plastic through a purely metallic Fibrous material significantly undercut. Even the density of 1.55 g / cnr of carbon fiber resin can pass through a purely metallic magnesium-lithium-nickel-titanium fiber material with e.g. 1.37 g / cnr for 2o vol.% corresponding to 25.5 wt.% magnesium, 7o vol.% corresponding to 27.2 % By weight lithium and io vol.% Corresponding to 47.3% by weight or 26% by weight nickel and 21.3% by weight titanium, which is solid up to above 220 ° C., are still below.

In general, the upper operating temperature is determined by the alloy ratio of magnesium to titanium Given the state of the art, the stability of the materials according to the invention by the content of up to above

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1200 ° C solid Aase with a CsCl structure.

The composition range of the magnesium base materials according to The invention is otherwise defined as the space-centered cubic AB-type phase generally for A the metals Nickel, cobalt and iron alone or in combination, for B the metals titanium, aluminum, beryllium individually or in combination within the stability limits of the ternary nickel-titanium starting from the two-component system nickel-titanium between 5o and 64 wt.% nickel, may contain quaternary or multi-component solid solution region. It is under these restrictions by the formula

^Ni lxy ^Co x ^Fe y ^Ti luv ^A1 u ^Be v ■ ** * -1 »y * L * <-l» vz.1 clearly defined, even if the composition range cannot be given in exact numbers without extensive experimental investigations. It can be varied further by the most varied of alloy additives, in particular by up to 30% by weight of chromium, up to 10% by weight of vanadium, up to 20% by weight of zirconium, up to 4% by weight of molybdenum and tungsten, up to 2% by weight .% Copper, up to 3 wt.% Manganese, up to 1 wt.% Silicon respectively. a combination of these elements.

The Mg-rich phase can contain up to 55% by weight lithium, up to 8% by weight aluminum, up to 8% by weight cadmium, up to 8% by weight Silver, up to 12% by weight zinc, up to 3% by weight manganese, up to 20% by weight indium, up to 2% by weight copper, up to 0.5% by weight Silicon, up to 4% by weight barium, up to 4% by weight strontium, up to 4% by weight cerium or cerium mixed metal, up to 2.5% by weight Didymium (neodymium + praseodymium), up to 4 wt.% Thorium, up to 1% by weight of zirconium, up to 0.1% by weight of beryllium, respectively. a combination of these elements in solid Solution included. In addition, further solid phases with a volume fraction of up to 20% can be used in the structure occur, which are formed by precipitation in the solid state from the two main phases, e.g. Ni ^ Ti, or else directly from a melt in connection with or even in equilibrium with the CsCl structure phase BEZW. with the Mg-rich phase are deposited. Also heard

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it zvjD. Scope of the invention that the elements of the magnesium-rich phase within the initially exclusively or predominantly metallic two- or multiphase material can be converted completely or partially by oxidation to high-temperature-resistant oxides and mg-rich phase themselves to oxide fibers or skeletons, for which now the body-centered cubic : Phase of the AB type alone forms the tough matrix.

Materials according to the invention can, depending on the alloy composition are manufactured by powder or melt metallurgy using a wide variety of master alloys, also as impregnating materials.

Due to the large difference in the melting points of the two main phases, it is advisable to introduce pellets from the granulated, specially pre-atomized high-melting phase into a magnesium-rich melt under vacuum, Protective gas resp. under a salt bath cover, as well as the sintering of powder mixtures in the presence of molten liquids Phase, even under increased pressure, to achieve particularly fine-grain alloys, preferably when for later deformation work the usually at Grain sizes of about 1 μm occurring micro-grain plasticity should be exploited. It is also important to achieve a fine grain of both phases and the highest strength values expedient, the molten materials with as possible high speed of e.g. more than 100 ° C / see by atomizing to powder or quenching, rolling and Drawing to cool foils, tapes or thin wires, which are used immediately or further processed by powder metallurgy will.

In the powder metallurgy production of the materials According to the invention, it is expedient if the prefabricated Iiegitrungepowder and metal powder already approximately the aforementioned Composition of the desired equilibrium

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phases of the materials. Only the meeting of the high ductility of the body-centered cubic phase of the NiTi type, which undergoes a martensite transformation at temperatures below 2oo ° C suffers, with the deformable magnesium-rich phase leads to the good ductile, novel Materials.

An essential feature of the subject matter of the invention is that these magnesium-based materials additionally through strong hot and cold deformation can be brought to the highest strength values, such as those of high-strength steels are known. There are practically two-fiber materials, the cross-section decreases down to a few μια fiber diameter and underneath respectively. such a plate thickness of the individual adjacent and superimposed crystallites of the two Allow phases thanks to their great extension. Intermediate annealing at temperatures below the solidus temperature the Mg-rich phase, in particular recrystallization annealing for this phase, are also used to soften the higher-melting phases body-centered cubic phase sufficient.

For the production of rolled or extruded profiles from materials According to the invention, it is advantageous to start from powder mixtures of the two phases, the grain sizes as fine as possible, e.g. have <60 μαι.

The body-centered cubic phase is expediently in the granulated or atomized, quenched or between 800 and looo ° C pre-annealed condition. To achieve a good fiber or platelet structure is repeated Extrusion, rolling, respectively. Pack rolling and, if necessary, drawing with intermediate annealing required.

Particularly favorable for the strength and elongation properties of the fiber materials described, it is when the composition, ΊβΓ both metallic structural components are coordinated so that both when rolling,

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Extrusion and / or drawing at the selected deformation temperature stretched roughly evenly in the direction of deformation. For the manufacture of materials with lamellas or Layer structure is it accordingly favorable when bezw by forging, upsetting, hammering, pressing, diagonal and / or Ereuzwalzen. in the event of explosive deformation the two metallic structural components perpendicular to the direction of deformation to flat, parallel lying Particles with roughly even stretching and spreading become.

Appropriate by adding up to 80 percent by volume of glass powder Grain size based on the entire volume of the material made from a type of glass with a low softening point below the solidus temperature of the Mg-rich phase, preferably from lead glass, one comes to three-fiber materials, with which particularly high resistance properties can be achieved are. Depending on the viscosity of the glass phase and the. Flow properties of the two solid metal phases with increased Temperature can BEZW the spatial arrangement of the individual fibers. Platelets in such glass fiber-metal composites varied as desired and the surface area of the individual phases can be increased significantly, so that in particular E.g. the glass fibers are completely isolated from each other and enclosed by metal fibers. The glass proportions shrink the cooling from the last annealing treatment is less than the metallic components due to their smaller thermal expansion, especially than the Mg phase, and thus, apart from their inherent strength, also have an additional strength-increasing effect on the metallic fibers. Compared to the usual separate production of glass fibers and strands and their Impregnation with metal or The production method described is special when it is introduced into a metallic melt economical and moreover delivers fairly uniform workpieces.

It is also possible to use a powder mixture of the two ductile metallic fibers from the outset up to

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7o vol.% High-strength fibers or threads, e.g. uncoated or with silicon carbide whiskers / liohlenstof fibers, ceramic Fibers, wore threads, glass threads, whiskers or drawn thin wires e.g. made of beryllium, stainless steel, Bring chrome alloys or tungsten or ceramic powder and fibers or corresponding strands, mats, fabrics and to compress them in the strand. The fiber orientation is strengthened in the extrusion direction Metal powder particles also stretched into fibers, they flow around the high-strength fibers that are in turn usually only slightly deform and, as far as endless threads are concerned, also into oriented pieces of fiber with a high length-to-diameter ratio, separated from each other by the magnesium-rich phase and the intermetallic phase of the NiTi type are separated.

Finally, heat treatments below the Mg melting point have a particular effect on the structure and properties of the Mg base mass, which are cured in a known manner or even cured by oxidation) ^ » * n> However, it is also possible to use the higher melting main phase after the non-cutting deformation below the melting temperature of the magnesium-rich phase by quenching and tempering BEZW. Cooling at a controlled rate to harden additionally over further solid phases initially remaining in solution.

w In all of the above-described sintering, annealing and heat treatments, it is advantageous that the particles of the two metallic phases by diffusion part at their interfaces adherent particularly be interconnected. The same applies to castings and die-castings made from memory materials according to the invention. These are characterized by a very favorable ratio of strength to density and allow particularly thin wall thicknesses of the parts.

The composite materials described above are particularly as

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Lightweight materials of high strength for space and aviation technology as well as for vehicle construction and engine parts suitable, but also for weapon technology, for sports equipment, containers and the like.

Instead of glass fiber or metal fiber reinforced plastic-based materials, they are available at much higher temperatures * - Temperatures can be used and allow low from the outset because of their higher strength and also transverse strength Wall thicknesses and thus further weight savings. In terms of connection technology, they do not cause any difficulties and are also easy to machine. When used at elevated temperatures in air, the Mg-rich phase is preferably protected by the formation of thin oxide films, but initially remains metallic in the Inside.

However, it is also possible to make this phase by annealing these alloys at constant or increasing To completely oxidize temperatures above the melting point and thus to metal ceramics with MgO respectively. complex Oxides and e.g. glass fiber inserts as high-melting ceramic phase components that come through held together the intermetallic phase of the NiTi type will. If the latter is also oxidized, its toughness is restored by a reduction treatment. The effect of pressure during the oxidation is used in particular to compress the resulting composite materials in balance for the possible shrinkage of the Mg phase.

This achieves a goal, especially for high oxide proportions, the good integration through a metallic phase, which was previously due to the poor wettability of oxides as starting materials by metals or alloys in the production of metal ceramics by impregnation and sintering processes has caused considerable technical difficulties and additionally required adhesive formers.

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There are shock-resistant and thermal shock-resistant high-temperature materials high pore-free, low density, with good thermal and electrical conductivity obtained, the at the same time have a high hardness and edge resistance and a high chemical and abrasive resistance, but can also be deformed without cutting or cutting. In particular, they are up to the melting point of the phase NiTi type can be used. You can use for electrical contacts, cutting materials, gas turbine blades, wear-resistant Machine parts for cold and hot work as damping materials, nozzle materials for solid fuel rockets, heat shields with cooling «when melting the metallic ante ils can be used, whereby compared to the relatively heavier tungsten-silver heat that has been customary up to now, in which the silver evaporates, the higher specific heat and heat of fusion of the metallic phase compared to Silver can be used cheaply. However, it is also possible to subsequently completely or completely remove the remaining metallic phase partially chemically - e.g. with hydrochloric acid - to dissolve or melt out of the oxide skeleton, - advantageously again in a magnesium melt - and to bring in other metals or alloys for this, e.g. a partial impregnation or full impregnation to be carried out with silver and thus to come to magnesium oxide-silver heat shields, By impregnating the received

* nen oxide skeletons with specifically light metals such as magnesium, Aluminum, silicon, sodium, potassium, lithium, beryllium or their alloys can be used for their part also non-cutting or deformable lightweight construction materials with good electrical and thermal conductivity properties or manufacture light metal bearings. A light magnesium oxide structure improves the creep properties of Metals of higher density such as lead, copper, cobalt, nickel, iron, zinc, germanium, also of precious metals such as silver, Gold and platinum group metals or their alloys

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and above all allows the saving of substantial amounts of metal for objects of a given size from these metallic ones Materials while largely maintaining or even improving their operating properties. For the production of deformable, dense composite bodies, it is important that the impregnation material easily penetrates all Cavities and especially capillary spaces can be introduced from which the high-melting metal phase of the NiTi-type was dissolved out or melted out that it is well wetted and even the increased strength values known from the solidification of extremely thin threads and layers in comparison to solid materials of the same composition. It is irrelevant whether or not particles the original, melted-out metallic phase remain locally enclosed in the oxide skeleton.

Application examples are the production of thermoelectric ^ magnetic and resistance materials as well as magnesium oxide-silver impregnating materials for base plates of silicon rectifiers instead of the heavier and more expensive tungsten-silver impregnating materials. Of course, the magnesium oxide skeletons, which normally occur as intermediate products, can also be used directly as reinforcing fibers, e.g. for plastics, as high temperature filters, as porous mats, catalyst carriers, carriers ceramic or metallic masses in dental prosthetics, substrates that are e.g. electroless or galvanic, by vapor deposition, spraying, dipping or pressing or coated with glasses, pastes, semiconductors or metal salts Can be filled as materials for fuel cells, ion exchange, material exchange, or with metallic filling as electrodes, as diffusion separation layers as well as welding filler materials,

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The metal ceramics described can be in any form as forgings and castings, die castings, elongated Molded parts such as rods, pipes, strips, foils, cladding are obtained, the latter e.g. via cladding, Overlay welding or application spraying of the metallic Starting materials. In each case there is an afterthought Oxidation required. It is always favorable that an alloy is formed between the two metallic ones Phases of the starting material and the to be armored respectively. covering documents occurs, which also applies to the following Oxidation is retained and causes the desired bond.

This is particularly true when the magnesium base materials according to the invention are used as ceramic solders. One has at the same time the advantage of a low working temperature, which, depending on the solder composition, is close to the melting point the Mg-rich phase can be selected down, the composition according to a reactive solder, and can still the Operating temperatures of the soldered parts after oxidation of the low-melting metallic phase to just below the melting point of the high-melting metallic starting phase. As ceramic solders, the materials are in accordance with Invention for metal ceramics as well as for full ceramics, graphite, carbon fiber materials and for high melting points Metals such as zirconium, tungsten, molybdenum, titanium, cast iron and their compounds can be used.

Particularly noteworthy is the suitability of the purely metallic Materials such as the partially oxidized materials or impregnating materials according to the invention as reactor materials because of their chemical resistance, easy shaping, good connection formation, their low neutron absorption cross-section, their favorable ratio of strength to density, their low cost price,

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their high heat resistance and low creep speed at higher temperatures.

The areas of application are, in particular, coatings for fuels and the lining of fuel assembly channels and pressure pipes.

Oxide skeletons produced according to the invention can use it but can also be soaked with uranium, plutonium or thorium and their alloys and as fission and breeding materials respectively After impregnation with beryllium, reflector materials serve as moderator materials, with cadmium and silver or indium or their alloys as materials for control organs, with lead as materials for shielding.

From the large number of possible metal-ceramic combinations, an impregnation material made of 50% by volume of magnesium kidney fibers with 50 VbI is just a particularly economical example. Silver with a density of only 7.5 g / cm 3 and made from 50% by volume of magnesium oxide fibers and 50% by volume of magnesium with a density of 2.67 g / cm 3, the fiber combinations MgO-NiTi-SiO ₂ and MgO-NiTi as highly heat-resistant composite types with embedded carbon fiber, which guarantees a high level of elasticity in addition to high tensile strength.

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Claims (1)

Dr. phil. W. Dannöhl _On ino / 1 ³ ' ³ * Claims. Two-phase magnesium base materials, characterized by that 5 to 97 wt.%, preferably 5 to 65 % By weight of the material composed of particles of a body-centered cubic phase of the AB type with a CsCl structure and Lattice constants between 2.6o and 3 »2o A exist, with A being the metals nickel, cobalt and iron, individually or combined, for B the metals titanium, aluminum and sometimes also beryllium, individually or in combination, can stand, while the second structural component is hexagonal or body-centered cubic, has a lower melting point than the phase with CsCl lattice and made of magnesium or a magnesium-lithium alloy with up to 55% by weight lithium and up to a total of 3% by weight of the elements of the phase with a CsCl lattice exists in solid solution. Two-phase magnesium-based materials according to claim 1, characterized in that the magnesium-rich phase up to up to 8% by weight of aluminum, up to 8% by weight of cadmium, up to 8% by weight of silver, up to 12% by weight of zinc, up to 3% by weight of manganese, up to 20% by weight indium, up to 2% by weight copper, up to 0.5% by weight silicon, up to 4% by weight barium, up to 4% by weight strontium, up to 4% by weight cerium or cerium mixed metal, up to 2.5% by weight didymium (neodymium + praseodymium), up to 4% by weight thorium, up to 1% by weight zirconium, up to o, l wt.% beryllium respectively. contains a combination of these elements in solid solution. Two-phase magnesium-based materials according to claims 1 and 2, characterized in that the phase with a CsCl structure up to 3o wt.% chromium, up to 10 wt.% vanadium, up to 2o wt.% zirconium, up to 4 wt.% molybdenum and -2-109839 / 0786 Tungsten, up to 2% by weight copper, up to 3% by weight manganese, up to 1 wt.% silicon respectively. contains a combination of these elements in solid solution. 4-. Two-phase magnesium base materials according to the claims 1 to 3 »characterized in that they are prepared by mixing and sintering from ready-made alloy powders and metal powders in approximately the aforementioned composition of the desired equilibrium phases of the material are made. 5. Two-phase magnesium base materials according to claims 1 to 4-, characterized in that it is produced by sintering in the presence of a liquid magnesium-rich phase are. 6. Two-phase magnesium base materials according to claims 1 to 5 »characterized in that the particles of the two metallic phases during sintering and annealing due to partial diffusion at their interfaces firmly bonded to one another are connected. 7. Two-phase magnesium base materials according to the claims 1 to 3, characterized in that they consist of homogeneous Melting through adapted cooling speed to form ingots, strands or castings with from the Grain size of both phases dependent on material strength and expansion. 8. From two-phase magnesium base materials according to the claims 1 to 7 fiber materials produced by rolling, extrusion and / or drawing, characterized in that the two metallic structural components are stretched approximately evenly in the deformation direction. 9. From two-phase magnesium base materials according to the claims 1 to 7 bezw by forging, upsetting, hammering, pressing, diagonal and / or cross rolling. by explosive deformation Manufactured materials with a lamellar or layer structure, characterized in that the two 109839/0785 / I * metallic structural components perpendicular to the direction of deformation to form flat, parallel particles with in have become roughly even stretching and spreading. 10. Multi-phase magnesium base materials with two main structural components according to claims 1 - Io, characterized in, that they are still up to 20 percent by volume contain further metallic phases which are in heterogeneous equilibrium with one or both main phases. 11. Multi-phase magnesium base materials according to claims 1-9 »characterized in that one of the two main structural components or both after the non-cutting deformation by quenching and tempering or cooling with controlled Speed can also be hardened via further solid phases initially remaining in solution. 12. Multi-phase magnesium base materials according to one or more of claims 1-6 and 8-11, characterized in that that they contain up to 80% by weight of a glass phase with a softening point below the solidus temperature of the magnesium-rich phase, which together with the metallic Phases have been deformed. 13. Multi-phase magnesium base materials according to one or more of claims 1 to 12, characterized in that They are prefabricated up to 70% by weight, but in composite material practically plastically undeformed carbon fibers, contain ceramic fibers, glass threads, boron threads and / or whiskers, which may need to be oriented in the production process Pieces of fiber with a high length to diameter ratio have been cut up. 14. Multi-phase magnesium base materials according to one or more of claims 1 to 6 and 8 to 13, that they are prefabricated contain high-melting and high-strength metallic wheels or fibers in a weight proportion of up to? b%, those in the composite material are only slightly plastic -.4.— 109839 / ^ 785 but may be deformed into oriented pieces of fiber have been cut with a high ratio of length to diameter 15. Two- and multi-phase metal ceramics made from Magnesium base materials according to one or more of Claims 1 to 14, characterized in that the magnesium-rich Phase is subsequently oxidized to magnesium oxide or complex oxides and the resulting metal ceramics are now held together by the metallic magnesium-free phase (s). 16. Magnesium oxide fibers, strands or bodies on magnesium-based materials according to one or more of claims 1 to 15, characterized in that they by complete or partial removal respectively. Melting out of the remaining metallic phases after oxidation the magnesium-rich phase. 17. Two- and multi-phase metal ceramics, manufactured using magnesium-based materials according to one or more of the Claims 1 to 16, characterized in that the resulting magnesium oxide skeletons are subsequently soaked respectively Introduction of metals, alloys, glasses, semiconductors, pastes, metal salts or plastics filled will. 18. Two- and multi-phase metal ceramics, manufactured by " Magnesium base materials according to one or more of Claims 1 to 17, characterized in that the filled or porous magnesium oxide skeletons electrolessly or galvanically, by vapor deposition, spraying on, dipping or Overpressing can be provided with a foreign transfer. 19 · Use of materials according to claims 1 to 1 as lightweight construction materials with high strength and low density for space and aviation technology, for vehicle construction and engine parts. —5— 109 8 39/0785 2Ü10841 2ο. Use of materials according to Claims 1 to for sports equipment, for containers and for weapon technology. 21. Use of materials according to claims 1-18 for electrical contacts, electrical conductive and resistance materials and magnetic materials. 22. Use of materials according to claims 1-18 as reactor materials. 23. Use of materials according to claims 1-18 as ceramic solders. "24. Use of materials according to claims 1-18 as catalysts, catalyst carriers, for ion exchange and material exchange. 25. Use of materials according to claims 1-18 as electrodes. 26. Use of materials according to claims 1-18 as welding filler materials. 27. Use of materials according to claims 1-18 in dental prosthetics. 28. Use of materials according to claims 1-18 for cutting purposes. 29. Use of materials according to claims 1-18 as highly heat-resistant materials for gas turbine blades, nozzles for solid fuel off rake th, Hitaeßchilde, bearings
and filters. 3o * Use of materials according to claims 1-18 for cladding and intermediate layers. 31. Use of materials according to claims 1-18 as reinforcing fibers and - mats for plastics and plastic masses " 32. Use of materials according to claims 1-18 as reinforcing fibers and mats for metals and alloys . 109839/0785