CN108367358A - The method for preparing the metal matrix composite materials for including inorganic particle and discontinuous fibre - Google Patents

Abstract

The invention provides a method for preparing porous metal matrix composite material. The method includes mixing a metal powder, a plurality of inorganic particles, and a plurality of discontinuous fibers to form a mixture, wherein the metal powder includes aluminum, magnesium, an aluminum alloy or a magnesium alloy. The method also includes sintering the mixture to form a porous metal matrix composite. Typically, the inorganic particles include porous particles or ceramic or glass bubbles, and the inorganic particles and discontinuous fibers are dispersed in the metal. Metal matrix composites have lower densities than metals and acceptable yield strengths.

Description

Method of making metal matrix composites comprising inorganic particles and discontinuous fibers

technical field

The present disclosure relates to methods of making metal matrix composites comprising a mixture of a metal substrate and other materials, such as filler materials.

Background technique

Metal matrix composites have long been considered promising materials due to their combination of high strength and stiffness combined with low weight. Metal matrix composites typically consist of a metal matrix reinforced with fibers or other filler materials.

Contents of the invention

The present disclosure provides methods for making lightweight metal matrix composites. There remains a need for methods of forming metal matrix composites with lower packing densities than metals, while maintaining certain levels of physical properties.

In one aspect, the present disclosure provides a method of making a porous metal matrix composite. The method includes mixing a metal powder, a plurality of inorganic particles, and a plurality of discontinuous fibers to form a mixture. The method also includes sintering the mixture to form a porous metal matrix composite. Typically, inorganic particles and discontinuous fibers are dispersed in the metal.

Various unexpected results and advantages are obtained in the exemplary embodiments of the present disclosure. An advantage of at least one exemplary embodiment of the present disclosure is the fabrication of a porous metal matrix composite comprising inorganic particles and discontinuous fibers dispersed in metal exhibiting a lower packing density than metal Both, and an acceptable yield strength (eg, plastic yield in a tensile stress-strain curve). Furthermore, according to at least some example embodiments of the present disclosure, it is not necessary to use any coating on the inorganic particles to provide a metal matrix composite having the inorganic particles effectively dispersed in the metal. In at least some exemplary embodiments of the present disclosure, the inorganic particles are generally intact within the metal matrix composite with minimal broken particles.

The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following description more particularly exemplifies exemplary embodiments. In several places throughout this application, guidance is provided through lists of examples, which examples can be used in various combinations. In each case, the recited list serves only as a representative group and should not be construed as an exclusive list.

Description of drawings

The present disclosure can be more fully understood from the following detailed description of various embodiments of the disclosure when considered in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic cross-sectional view of a metal matrix composite fabricated according to an exemplary embodiment of the present disclosure.

2 is a graph of stress-strain curves for exemplary and comparative substrates prepared according to the present disclosure.

3 is a graph of stress-strain curves for additional exemplary and comparative substrates.

4 is a graph of stress-strain curves for additional exemplary and comparative substrates.

5 is a graph of a stress-strain curve for another exemplary substrate.

6 is a graph of a stress-strain curve for another exemplary substrate.

7 is a graph of a stress-strain curve for another exemplary substrate.

While the above figures, which may not be to scale, illustrate embodiments of the disclosure, other embodiments are also contemplated, as noted in the detailed description.

Detailed ways

For the following glossary of defined terms, unless a different definition is provided in the claims or elsewhere in the specification, these definitions shall control throughout the application.

Glossary

Certain terms are used throughout the specification and claims which, although mostly familiar, may still require some explanation. It should be understood that as used herein:

As used in this specification and the appended embodiments, the singular forms "a", "an" and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended embodiments, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

As used in this specification, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.8, 4, and 5).

Unless otherwise indicated, all numerical values expressed in amounts or components, measures of properties, etc. used in the specification and embodiments are to be understood in all instances as being modified by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and accompanying List of Embodiments can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings of this disclosure. At the very least, and without attempting to limit the application of the doctrine of equivalents to the scope of the claimed embodiments, should at least be construed in light of the number of significant digits reported and by applying customary rounding techniques for each numeric parameter.

The terms "comprises" and variations thereof do not have a limiting meaning where these terms appear in the description and claims.

The words "preferred" and "preferably" refer to embodiments of the disclosure that afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present disclosure.

References throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments," or "an embodiment," whether or not the term "exemplary" precedes the term "embodiment" All mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one of the certain exemplary embodiments of the present disclosure. Thus, throughout the specification, phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment," "in many embodiments," or "in "in an embodiment" does not necessarily refer to the same embodiment as certain exemplary embodiments of the present disclosure. Furthermore, particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

The term "dispersed" with respect to one or more fillers in a metal matrix means that the one or more fillers are distributed throughout the metal matrix, for example to provide a substantially uniform metal matrix comprising metal and one or more fillers. Matrix composites. This is in contrast to regions of the metal matrix composite having a concentration of one or more fillers up to at least twice that of one region in a different location of the metal matrix composite (e.g., a layer of filler within a metal matrix composite or clusters). The one or more fillers are still dispersed in the metal, although sufficiently small volumes of metal matrix composites in which the one or more fillers are not completely uniformly distributed in the metal matrix may be observed.

The term "sintering" refers to the agglomeration of powdered material into a solid or porous mass by heating it without complete liquefaction. Optionally, the powder material is also compressed during sintering.

The term "encapsulation density" with respect to particles refers to the mass divided by the encapsulation volume. "Enveloped volume" refers to the sum of the volumes of the solids in each particle and any voids in the particle. Similarly, the term "enveloped density" with respect to metal matrix composites refers to the mass divided by the enclosed volume, where "enclosed volume" refers to the density of solids in the metal matrix composite and any voids in the metal matrix composite. sum of volumes.

The term "skeleton density" with respect to porous particles refers to the mass divided by the skeletal volume. "Skeleton volume" refers to the sum of the volumes of the solid material and any closed pores within the particle.

The term "average true density" with respect to glass bubbles refers to the average value of the density of the glass bubbles, not the density of a volume of glass bubbles (which depends on the degree of compaction of the glass bubbles in the volume).

The term "plastic yield" refers to the stress at which a predetermined amount of permanent deformation of a material occurs.

The term "tensile plastic yield" refers to the stress at which a predetermined amount of permanent deformation of a material occurs when the material is subjected to a tensile force.

The term "softening point" refers to the temperature or range of temperatures at which a material (eg, in a solid phase) begins to collapse under its own weight. For materials with well-defined melting points (eg, metals), the softening point is generally considered to be the melting point of the metal or metal alloy. However, for materials that do not have a defined melting point, the softening point may be the temperature at which the elastic properties of the material change to plastic flow. For example, the softening point of glass, glass-ceramic, or porcelain may occur at the glass transition temperature of the material and may be defined by a viscosity of 10 ^7.65 poise. The softening point of glass is typically determined, for example, by the Vicat method (eg, ASTM-D1525 or ISO 306) or by the Heat Deflection Test (eg, ASTM-D648).

The term "uncoated" with respect to a glass bubble means the absence of any additional material (ie, having a composition other than glass) applied to the exterior surface of the glass bubble.

The term "yield strength" refers to the stress at which plastic elongation of a material is considered to have begun. As used herein, yield strength is determined at an offset of 0.2%. ASTM B557M-15 discloses "7.6 Yield Strength—Determination of Yield Strength by Offset Method at 0.2% Offset. The pass or fail of the material can be determined based on the Extension-Under-Load Method (Extension-Under-Load Method). For arbitration For testing, the offset method should be used. 7.6.1 Offset method—In order to determine the yield strength by the "offset method", it is necessary to ensure data (automatically recorded or numerical) from which the stress-strain diagram can be drawn. Then in the stress- On the strain diagram (Figure 16), lay off Om equal to the specified value of the offset, draw mn parallel to OA, and thus locate the intersection of r,mn with the stress-strain diagram (Note 12). In the report When yield strength values are obtained by this method, the specified value of "offset" used should be stated in parentheses after the term yield strength. Hence: yield strength (offset = 0.2%) = 360 MPa".

The term "transition alumina" refers to any alumina from aluminum hydroxide to alpha alumina. Particular transitional alumina particles include delta alumina, eta alumina, theta alumina, chi alumina, kappa alumina, rho alumina, and gamma alumina. Transitional alumina particles are formed during the heat treatment of aluminum hydroxide or aluminum oxyhydroxide. The most thermodynamically stable form is usually alpha alumina.

Various exemplary embodiments of the present disclosure will now be described. Various modifications and changes may be made to the exemplary embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. Accordingly, it should be understood that embodiments of the present disclosure are not limited to the exemplary embodiments described below, but are to be controlled by the limitations set forth in the claims and any equivalents thereto.

In one aspect, the present disclosure provides a method of making a porous metal matrix composite. The method includes mixing a metal powder, a plurality of inorganic particles, and a plurality of discontinuous fibers to form a mixture. The method also includes sintering the mixture to form a porous metal matrix composite.

In some embodiments, the mixing of metal powders, inorganic particles, and discontinuous fibers is performed manually, such as by shaking the container holding the materials by hand. Typically, shaking is performed for at least 15 seconds, at least 20 seconds, at least 30 seconds, at least 45 seconds, or at least 60 seconds, and up to 2 minutes, up to 100 seconds, up to 90 seconds, or up to 70 seconds. When manually mixing the components for the metal matrix composite, the container holding the material is optionally inverted at least once. In certain embodiments, the mixing of metal powders, inorganic particles, and discontinuous fibers is performed using acoustic mixers, mechanical mixers, shaker tables, or tumblers. Mixing using equipment can similarly be carried out for at least 15 seconds, at least 20 seconds, at least 30 seconds, at least 45 seconds, or at least 60 seconds, and up to 2 minutes, up to 100 seconds, up to 90 seconds, or up to 70 seconds. The mixture produced by mixing the components includes inorganic particles and discontinuous fibers dispersed in the metal powder. As discussed above, having inorganic particles and discontinuous fibers dispersed in the metal powder provides a substantially homogeneous mixture.

After mixing, the mixture is sintered. In most embodiments, sintering is carried out for a period of at least 30 minutes, at least 60 minutes, at least 90 minutes, or at least 2 hours, and up to 3 hours or up to 24 hours; such as between 30 minutes and 3 hours (including end value). Typically, the mixture is sintered in a mold (eg, mold). Sintering is typically carried out in a hot press or furnace at temperatures of at least 250 degrees Celsius (°C), at least 300°C, at least 400°C, at least 500°C, or at least 600°C, and up to 1,000°C, up to 900°C, up to To 800°C or up to 700°C; such as between 250°C and 1,000°C (inclusive) or between 400°C and 900°C or between 600°C and 800°C. In many embodiments, the temperature is increased at a steady rate until the desired maximum temperature is reached.

In certain embodiments, sintering also includes applying pressure to the mixture in the mold. For example, sintering is optionally performed at a pressure of at least 4 megapascals (MPa), at least 5 MPa, at least 7 MPa, at least 10 MPa, at least 12 MPa, at least 15 MPa, or at least 20 MPa; and up to 200 MPa, up to 150 MPa, up to 100 MPa , up to 75MPa, up to 50MPa or up to 25MPa; such as between 4MPa and 200MPa (inclusive), between 4MPa and 50MPa (inclusive) or between 15MPa and 200MPa (inclusive). In certain embodiments, the mold is flushed with an inert gas (eg, nitrogen or argon) after the applied pressure is released.

Following the sintering process, the metal matrix composite may be allowed to cool (eg, in or outside of a hot press or furnace). In some embodiments, the metal matrix composite furnace is allowed to cool (ie, by shutting down the furnace and waiting for the metal matrix composite to cool down on its own). In other embodiments, a coolant, such as, without limitation, an inert gas (eg, nitrogen, argon, etc.) is passed through the hot press or furnace to help the metal matrix composite cool down faster.

Referring to FIG. 1 , a schematic cross-sectional view of a porous metal matrix composite 100 prepared in accordance with an exemplary embodiment of the present disclosure is provided. Porous metal matrix composite 100 includes metal 10 , a plurality of inorganic particles 12 , and a plurality of discontinuous fibers 14 . Inorganic particles 12 and discontinuous fibers 14 are dispersed in metal 10 . For simplicity, the metal matrix composite is shown as having a single piece shape; however, the metal matrix composite may be formed into a number of various shapes depending on the intended application. Metal matrix composites are useful in industries such as construction, automotive and electronics, where specific metal components can be substituted for metal matrix composite components.

In many embodiments, the metal comprises a porous matrix structure. Porous matrix structures are generally obtained from powdered metals, where the powder contains the metal structure, where a gas (eg, air) is incorporated into the solid metal structure. Typically, the metal is present in an amount of 50% or more, 55% or more, 60% or more, 65% or more, 70% or more or 75% by weight of the metal matrix composite or more; and present in an amount of 95% by weight or less, 90% by weight or less, 85% by weight or less, or 80% by weight or less. In other words, the metal may be present in an amount between 50% and 95% by weight of the metal matrix composite, inclusive, or between 70% and 95% by weight of the metal matrix composite, inclusive. ). Metals include aluminum, magnesium, or alloys thereof (ie, aluminum alloys or magnesium alloys). Suitable metals include, for example and without limitation, pure aluminum (aluminum powder having a purity of at least 99.0%, e.g., AA1100, AA1050, AA1070, etc., such as commercially available from Eckart (Louisville, KY) obtained pure aluminum powder); or an aluminum alloy comprising aluminum and 0.2% to 2% by mass of another metal. Such alloys include: Al-Cu alloys (AA2017, etc.), Al-Mg alloys (AA5052, etc.), Al-Mg-Si alloys (AA6061, etc.), Al-Zn-Mg alloys (AA7075, etc.) and Al-Mn alloys, It exists alone or as a mixture of two or more. Various suitable metal powders are commercially available from Atlantic Equipment Engineers (Upper Saddle River, NJ).

Typically, when the metal is used in powder form, the metal powder includes an average particle size of 300 nanometers (nm) or greater, 400 nm or greater, 500 nm or greater, 750 nm or greater, 1 micrometer (μm) or greater Large, 2 μm or larger, 5 μm or larger, 7 μm or larger, 10 μm or larger, 20 μm or larger, 35 μm or larger, 50 μm or larger, or 75 μm or larger; and 100 μm or smaller, 75 μm or Smaller, 50 μm or less, 35 μm or less, or 25 μm or less. In other words, the metal powder comprises an average particle size in the range between 300 nm and 100 μm inclusive; in the range between 1 μm and 100 μm inclusive; or in the range between 1 μm and 50 μm inclusive . Particle size can be analyzed, for example, using light microscopy and laser diffraction.

Suitable inorganic particles include particles having an particles with the maximum packing density. Typically, the plurality of inorganic particles comprise substantially spherical or needle-shaped shapes, and in some embodiments, the inorganic particles comprise multicavity cells. The particles typically have an aspect ratio of longest axis to shortest axis of 2:1 or less.

Typically, the plurality of inorganic particles includes an average particle size of 50 nanometers (nm) or greater, 250 nm or greater, 500 nm or greater, 750 nm or greater, 1 micron (μm) or greater, 2 μm or greater, 5 μm or greater, 7 μm or greater, 10 μm or greater, 20 μm or greater, 35 μm or greater, 50 μm or greater, 75 μm or greater, or 100 μm or greater; and 5 millimeters (mm) or less, 3 mm or less, 2 mm or less, 1 mm or less, 750 μm or less, 500 μm or less, or 250 μm or less. In other words, the plurality of inorganic particles comprises an average particle size ranging between 50 nm and 5 mm inclusive; between 1 μm and 1 mm inclusive; or between 10 μm and 500 μm inclusive. end value).

The amount of inorganic particles dispersed in the metal is not particularly limited. The plurality of inorganic particles is typically present in an amount of at least 1%, at least 2%, at least 5%, at least 8%, at least 10%, at least 15%, or at least 20% by weight; and up to 50% by weight, up to 28% by weight, up to 26% by weight, up to 24% by weight, or up to 22% by weight of the metal matrix composite. In certain embodiments, the inorganic particles are present in the metal matrix composite in an amount between 1% and 30% by weight or between 2% and 25% by weight or between 2% and 15% by weight of the metal matrix composite % between (inclusive). Including less than 1% by weight of inorganic particles resulted in a minimal decrease in the packing density of the metal matrix composite, while including more than 30% by weight of inorganic particles adversely affected the mechanical properties of the metal matrix composite due to the fact that the metal matrix composite Material contains insufficient amounts of metal and fibers.

In certain embodiments, the plurality of inorganic particles includes porous particles. As used herein, "porous particle" refers to particles that themselves have pores as well as agglomerates of non-porous primary particles that include pores between at least some of the non-porous primary particles. Examples of useful porous particles include, for example and without limitation, porous metal oxide particles, porous metal hydroxide particles, porous metal carbonates, porous carbon particles, porous silica particles, porous dehydrated aluminosilicate particles, porous dehydrated Metal hydrate particles, zeolite particles, porous glass particles, expanded perlite particles, expanded vermiculite particles, porous sodium silicate particles, engineered porous ceramic particles, agglomerates of non-porous primary particles, or combinations thereof. In certain embodiments, the metal of the metal oxide, metal hydroxide, or metal carbonate is selected from aluminum, magnesium, zirconium, calcium, or combinations thereof. In select embodiments, the porous particles include porous alumina particles, porous carbon particles, porous silica particles, porous aluminum hydroxide particles, or combinations thereof. Porous particles typically have associated water removed therefrom, typically by heating the porous particles. Optionally, the porous particles include transitional alumina particles. Suitable porous particles include, for example and without limitation, Versal 250 boehmite powder, YH-D 16 Boehmite powder, commercially available from UOP LLC (Des Plaines, IL) Stone powder (Zibo Yinghe Chemical Company, Ltd. (Shandong, China)) and Alumax PB300 boehmite (PIDC International (Ann Arbor, MI)) ).

In certain embodiments, the plurality of inorganic particles comprises ceramic or glass bubbles. Suitable materials for ceramic and glass bubbles include, for example and without limitation, alumina, aluminosilicates, silica, or combinations thereof. Commercially available glass bubbles include, for example, LightStar, EconoStar, and High Alumina cenospheres, commercially available from Cenostar Corporation (Amesbury, MA) . Preferably, ceramic and glass bubbles are uncoated (eg, with metallic materials, which have been used to aid wetting of the bubbles by metal substrates).

In embodiments where the metal has a high melting point (e.g. aluminum) and the inorganic particles are glass bubbles, the plurality of (e.g. uncoated) glass bubbles advantageously comprise heat that withstands temperatures up to 700 degrees Celsius for at least 2 hours without softening glass. The use of high temperature resistant glass bubbles allows their incorporation into metal matrix composites that would otherwise be prepared at temperatures high enough to damage the glass bubbles, such as by softening at least some of the glass bubbles until they deform and/or or broken points.

One class of suitable glass bubbles includes bubbles that leach less than 100 micrograms of sodium ions per gram of glass bubbles in deionized water when stirred with the deionized water for 2 hours. An advantage of glass bubbles with such low sodium leaching rates is that they can be used in electronic applications where leaching of sodium ions is generally unacceptable. In one embodiment, suitable compounds for making such low-sodium glass bubbles include silica, lime, boric acid, calcium phosphate, calcined aluminum silicate, and magnesium silicate. In certain embodiments, such low-sodium glass bubbles exhibit a softening temperature between 717°C and 735°C, inclusive, as measured by thermal dilatometry.

Preferably, the inorganic particles comprise uncoated inorganic particles. Advantageously, the use of uncoated inorganic particles provides savings in material cost and coating time. Porous metal matrix composites are prepared according to methods of at least some embodiments of the present disclosure, wherein inorganic particles are dispersed in the metal and do not require any additional material to improve contact between the inorganic particles and the metal.

The plurality of discontinuous fibers dispersed in the metal matrix composite is not particularly limited, and includes, for example, inorganic fibers such as glass, alumina, aluminosilicate, carbon, basalt, or combinations thereof. More specifically, in certain embodiments, the fibers comprise at least one metal oxide, alumina, alumina-silica, or combinations thereof. Discontinuous fibers have an average length of less than 5 cm, which tends to facilitate better dispersion in the metal matrix than longer fibers. In many embodiments, the fibers have an average length that is shorter than the smallest dimension of the form or die used to form the metal matrix composite so that the orientation of the fibers is not constrained by the form or die. Typically, the ratio of fiber length to smallest dimension of the form or mold is <1:1. In certain embodiments, the average length of the discontinuous fibers is less than 4 centimeters, less than 3 centimeters, or less than 2 centimeters. Discontinuous fibers can be formed from continuous fibers, for example, by methods known in the art, such as chopping and grinding. Typically, the plurality of discontinuous fibers includes an aspect ratio of 10:1 or greater.

Suitable discontinuous fibers can be of various compositions, such as ceramic fibers. Ceramic fibers can be produced in continuous lengths that are chopped or sheared as discussed herein to provide ceramic fibers of the present disclosure. Ceramic fibers can be produced from a variety of commercially available ceramic filaments. Examples of filaments that can be used to form ceramic fibers include ceramic oxide fibers sold under the trademark NEXTEL (3M Company, St. Paul, MN). NEXTEL is a continuous filament ceramic oxide fiber with low elongation and shrinkage at operating temperatures, and offers good chemical resistance, low thermal conductivity, thermal shock resistance, and low porosity. Specific examples of NEXTEL fibers include NEXTEL 312, NEXTEL 440, NEXTEL 550, NEXTEL 610, and NEXTEL 720. NEXTEL 312 and NEXTEL 440 are refractory aluminoborosilicates including Al ₂ O ₃ , SiO ₂ and B ₂ O ₃ . NEXTEL 550 and NEXTEL 720 are aluminosilica and NEXTEL 610 is alumina. During manufacture, NEXTEL filaments are coated with organic sizing or finishing agents used as aids in textile processing. Coatings may include the use of starches, oils, waxes or other organic ingredients applied to the filament strands to protect and aid in handling. Coatings can be removed from ceramic filaments by thermally cleaning the filaments or ceramic fibers at a temperature of 700° C. for 1 to 4 hours.

Ceramic fibers may be cut or chopped to provide relatively uniform lengths, which may be achieved by cutting continuous filaments of ceramic material in a mechanical shearing operation or a laser cutting operation, among other cutting operations. Due to the highly controlled nature of such cutting operations, the size distribution of the ceramic fibers is very narrow and allows control of the composite properties.

The length of the ceramic fiber can be measured, for example, using an optical sensor equipped with a CCD camera (Olympus DP72, Tokyo, Japan) and analysis software (Olympus Stream Essentials (Olympus Stream Essentials, Tokyo, Japan)). Microscope (Olympus MX61, Tokyo, Japan) measurement. Samples can be prepared by spreading a representative sample of ceramic fibers on a glass slide and measuring the length of at least 200 ceramic fibers at 10X magnification.

Suitable fibers include, for example, ceramic fibers such as NEXTEL 312, 440, 610, and 720 commercially available under the trade designation NEXTEL (available from 3M Company, St. Paul, MN). One presently preferred ceramic fiber comprises polycrystalline α-Al ₂ O ₃ . Suitable alumina fibers are described, for example, in US Patent 4,954,462 (Wood et al.) and US Patent 5,185,299 (Wood et al.). Exemplary alpha alumina fibers are sold under the trade designation NEXTEL 610 (3M Company, St. Paul, MN). In some embodiments, the alumina fibers are polycrystalline alpha alumina fibers and comprise (based on theoretical oxides) greater than 99% by weight Al ₂ O ₃ and 0.2-0.5% by weight SiO ₂ , based on the total weighing scale. In other embodiments, some desirable polycrystalline alpha alumina fibers comprise alpha alumina having an average grain size of less than 1 micron (or even less than 0.5 micron in some embodiments). In some embodiments, the polycrystalline alpha alumina fibers have an average tensile strength of at least 1.6 GPa (in some embodiments, at least 2.1 GPa, or even at least 2.8 GPa). Suitable aluminosilicate fibers are described, for example, in US Patent 4,047,965 (Karst et al.). Exemplary aluminosilicate fibers are sold under the trade designations NEXTEL 440 and NEXTEL 720 by 3M Company (St. Paul, MN). Aluminoborosilicate fibers are described, for example, in US Patent 3,795,524 (Sowman). An exemplary aluminoborosilicate fiber is sold under the tradename NEXTEL 312 by 3M Company. Boron nitride fibers can be made, for example, as described in US Patent 3,429,722 (Economy) and US Patent 5,780,154 (Okano et al.).

Ceramic fibers may also be formed from other suitable ceramic oxide filaments. Examples of such ceramic oxide filaments include those commercially available from Central Glass Fiber Co., Ltd. (eg, EFH75-01, EFH150-31). Also preferred are aluminoborosilicate glass fibers that contain less than about 2% alkali or are substantially free of alkali (ie, "E-glass" fibers). E-glass fibers are available from a number of commercial suppliers.

The amount of discontinuous fibers dispersed in the metal matrix composite is not particularly limited. The plurality of fibers is typically present in an amount of at least 1%, at least 2%, at least 3%, at least 5%, at least 10%, at least 15%, at least 20% by weight of the metal matrix composite or the metal matrix at least 25% by weight of the composite material; and up to 50% by weight, up to 45% by weight, up to 40% by weight, or up to 35% by weight of the metal matrix composite. In certain embodiments, the fibers are present in the metal matrix composite in an amount between 1% and 50% by weight or between 2% and 25% by weight or between 5% and 15% by weight of the metal matrix composite between (inclusive). Including less than 1% by weight of fibers resulted in minimal increase in the strength of the metal matrix composite, while inclusion of more than 50% by weight of fibers adversely affected the packing density of the metal matrix composite due to the insufficient inclusion of amount of metal and inorganic particles. In certain embodiments, the plurality of inorganic particles and the plurality of discontinuous fibers are present in combination in an amount between 5% and 50% by weight of the metal matrix composite, inclusive.

Advantageously, metal matrix composites exhibit reduced packing density (compared to pure metals) and acceptable mechanical properties. For example, metal matrix composites typically have an encapsulation density between 1.35 and 2.70 grams per cubic centimeter, inclusive, or between 1.80 and 2.50 grams per cubic centimeter, inclusive. For example, the metal matrix composite material can have an an encapsulated density; and an encapsulated density of up to 2.70 grams per cubic centimeter, up to 2.60 grams per cubic centimeter, up to 2.50 grams per cubic centimeter, up to 2.40 grams per cubic centimeter, or up to 2.30 grams per cubic centimeter.

In certain embodiments, the metal comprises aluminum or an alloy thereof, and the metal matrix composite has an encapsulation density between 1.80 and 2.50 grams per cubic centimeter, inclusive; between 2.00 and 2.30 grams per cubic centimeter (inclusive); or between 1.80 and 2.20 g/cm3 (inclusive).

In certain embodiments, the metal comprises magnesium or an alloy thereof, and the metal matrix composite has an encapsulation density of between 1.35 and 1.60 grams per cubic centimeter, inclusive; between 1.55 and 1.60 grams per cubic centimeter (inclusive); or between 1.35 and 1.50 g/cm3 (inclusive).

Advantageously, in many embodiments, the metal matrix composite has an encapsulation density that is at least 8% less (or at least 10% less, at least 12% less, at least 15% less, or at least 17% less) than the density of the metal, and Can withstand 1% strain before breaking. This combination of properties provides lightweighting of the metal and retains some of the metallic character in the metal matrix composite. In particular, metal matrix composites preferably exhibit yield strength prior to failure in tensile testing. In certain embodiments, the metal matrix composite has a yield strength of 50 MPa or greater, 75 MPa or greater, 100 MPa or greater, 150 MPa or greater, or 200 MPa or greater.

It has been found that the metal matrix composites of at least some exemplary embodiments of the present disclosure exhibit stress-strain curves exhibiting plastic yield behavior, and that the metal matrix composites of at least some exemplary embodiments of the present disclosure exhibit Stress-strain curves for tensile-plastic yield performance. That is, the region where the stress-strain curve exhibits plastic flow. Plastic yield curves and tensile-plastic yield curves are contrasted with purely brittle failure mechanisms. That is, a purely brittle behavior exhibits only an elastic region within the stress-strain curve, with no (or very little) plastic flow region. Surprisingly, the combination of inorganic particles and discontinuous fibers as fillers in metal matrix composites according to at least some embodiments of the present disclosure provided plastic yield curve and/or tensile plastic yield properties when tested. For example, referring to Figure 3, the stress-strain curve of Example 13 (described in detail below) comprising both fibers and porous inorganic particles shows yielding prior to the brittle failure mechanism. In certain embodiments, the metal matrix composite can withstand 1%, 1.5%, or 2% strain before fracture. Furthermore, surprisingly, the metal powder remains separate from the porous inorganic particles as opposed to being pushed into some of the pores of the porous inorganic particles during sintering, especially sintering under applied pressure. Interestingly, the porous inorganic particles also do not tend to become damaged (eg, crumble or crush) during sintering, but rather retain their porous framework structure.

In many embodiments, the metal matrix composite exhibits 25 megapascals (MPa) or greater, such as 40 MPa or greater, 50 MPa or greater, 75 MPa or greater, 100 MPa or greater, 150 MPa or greater, 200 MPa or greater. Greater, 250 MPa or greater, or 300 MPa or greater ultimate tensile strength. This can also be used to consider the tensile strength of metal matrix composites as it relates to the encapsulation density of metal matrix composites, since usually tensile strength is sacrificed during lightweighting of composites. In some embodiments, the metal matrix composite has an encapsulation density between 1.80 and 2.50 grams per cubic centimeter, inclusive, and 50 MPa or greater, 100 MPa or greater, 150 MPa or greater, 200 MPa or greater , 250MPa or greater or 300MPa or greater ultimate tensile strength.

Advantageously, in certain embodiments, desired mechanical properties are achieved without the need for fillers other than inorganic particles and discontinuous fibers. In such embodiments, the metal matrix composite consists essentially of metal, a plurality of inorganic particles, and a plurality of discontinuous fibers. The metal matrix composite can therefore also contain additives which do not significantly affect the mechanical properties of the metal matrix composite. In contrast, metal matrix composites consisting essentially of a metal, a plurality of inorganic particles, and a plurality of discontinuous fibers may additionally include additives, such as materials to aid in the dispersion of fillers.

Metal matrix composites according to aspects of the present disclosure may be prepared according to various suitable methods known to the skilled practitioner, including powder metallurgy processes such as hot pressing, powder extrusion, hot rolling, warm rolling followed by heating, cold compaction and sintering as well as hot isostatic pressing. In one embodiment, metal matrix composites can be formed by mixing metal powder, a plurality of inorganic particles, and a plurality of discontinuous fibers to disperse the inorganic particles and discontinuous fibers in the metal powder, and then sintering the mixture to form a metal matrix composite material to prepare. For example, this powder metallurgy method is described in detail in Example 1 below.

Exemplary implementation

Embodiment 1 is a method of preparing a porous metal matrix composite. The method includes mixing a metal powder, a plurality of inorganic particles, and a plurality of discontinuous fibers to form a mixture. The method also includes sintering the mixture to form the porous metal matrix composite.

Embodiment 2 is the method of embodiment 1, wherein the mixture is sintered in a mold.

Embodiment 3 is the method of embodiment 1 or embodiment 2, wherein the sintering is performed at a temperature between 250 degrees Celsius and 1,000 degrees Celsius, inclusive.

Embodiment 4 is the method of any one of embodiments 1 to 3, wherein the sintering includes applying pressure.

Embodiment 5 is the method of embodiment 4, wherein the sintering is performed at a pressure between 4 MPa and 200 MPa, inclusive.

Embodiment 6 is the method of any one of embodiments 1 to 5, wherein the sintering is carried out for a time between 30 minutes and 3 hours, inclusive.

Embodiment 7 is the method of any one of embodiments 1 to 6, wherein the mixing is performed using an acoustic mixer, a mechanical mixer, or a tumbler.

Embodiment 8 is the method of any one of embodiments 1 to 7, wherein the mixture includes the inorganic particles and the discontinuous fibers dispersed in the metal powder.

Embodiment 9 is the method of any one of embodiments 1 to 8, wherein the metal matrix composite has an encapsulation density that is at least 8% less than that of the metal and is capable of withstanding 1% of the strain.

Embodiment 10 is the method of embodiment 9, wherein the metal matrix composite is capable of withstanding 2% strain before fracture.

Embodiment 11 is the method of any one of embodiments 1 to 10, wherein the metal matrix composite has a yield strength of 50 MPa or greater.

Embodiment 12 is the method of any one of embodiments 1 to 11, wherein the metal matrix composite has a yield strength of 100 MPa or greater.

Embodiment 13 is the method of any one of embodiments 1 to 12, wherein the metal matrix composite has an ultimate tensile strength of 100 MPa or greater.

Embodiment 14 is the method of any one of embodiments 1 to 13, wherein the metal matrix composite has an ultimate tensile strength of 200 MPa or greater.

Embodiment 15 is the method of any one of embodiments 1 to 14, wherein the metal matrix composite has an ultimate tensile strength of 300 MPa or greater.

Embodiment 16 is the method of any one of embodiments 1 to 15, wherein the plurality of inorganic particles comprises porous particles.

Embodiment 17 is the method of embodiment 16, wherein the porous particles have a maximum packing density of 2 grams per cubic centimeter or less.

Embodiment 18 is the method of embodiment 15 or embodiment 16, wherein the porous particles comprise porous metal oxide particles, porous metal hydroxide particles, porous metal carbonates, porous carbon particles, porous silica Granules, porous dehydrated aluminosilicate particles, porous dehydrated metal hydrate particles, zeolite particles, porous glass particles, expanded perlite particles, expanded vermiculite particles, porous sodium silicate particles, engineered porous ceramic particles, non-porous primary particles aggregates or their combinations.

Embodiment 19 is the method of any one of embodiments 16 to 18, wherein the porous particles comprise porous alumina particles, porous carbon particles, porous silica particles, porous aluminum hydroxide particles, or combinations thereof.

Embodiment 20 is the metal matrix composite of embodiment 19, wherein the porous particles comprise transitional alumina particles.

Embodiment 21 is the method of any one of embodiments 1-15, wherein the plurality of inorganic particles comprises ceramic or glass bubbles.

Embodiment 22 is the method of embodiment 21, wherein the glass bubble comprises glass that withstands heating to a temperature of 700 degrees Celsius for at least 2 hours without softening.

Embodiment 23 is the method of embodiment 21 or embodiment 22, wherein the glass bubbles leach less than 100 micrograms of sodium ions per gram of glass bubbles in the deionized water when stirred with the deionized water for 2 hours .

Embodiment 24 is the method of any one of embodiments 1 to 23, wherein the plurality of inorganic particles comprises a maximum packing density of 2 grams per cubic centimeter or less.

Embodiment 25 is the method of any one of embodiments 21 to 23, wherein the plurality of inorganic particles comprises alumina, aluminosilicate, silica, or combinations thereof.

Embodiment 26 is the method of any one of embodiments 18 to 21 , 24, or 25, wherein the inorganic particles comprise multicavitated cells.

Embodiment 27 is the method of any one of embodiments 1 to 26, wherein the plurality of inorganic particles has a substantially spherical shape or acicular shape.

Embodiment 28 is the method of any one of embodiments 1 to 27, wherein the plurality of inorganic particles has an average particle size ranging between 50 nanometers (nm) and 5 millimeters (mm), inclusive.

Embodiment 29 is the method of any one of embodiments 1 to 28, wherein the plurality of inorganic particles has an average particle size ranging between 1 micrometer (μm) and 1 mm, inclusive.

Embodiment 30 is the method of any one of embodiments 1 to 29, wherein the plurality of inorganic particles has an average particle size ranging between 10 μm and 500 μm, inclusive.

Embodiment 31 is the method of any one of embodiments 1 to 30, wherein the plurality of discontinuous fibers comprises glass, alumina, aluminosilicate, carbon, basalt, or combinations thereof.

Embodiment 32 is the method of any one of embodiments 1 to 31, wherein the plurality of discontinuous fibers has an aspect ratio of 10:1 or greater.

Embodiment 33 is the method of any one of embodiments 1 to 32, wherein the metal comprises a porous matrix structure.

Embodiment 34 is the method of any one of embodiments 1 to 33, wherein the metal comprises aluminum or an alloy thereof.

Embodiment 35 is the method of any one of embodiments 1 to 34, wherein the metal matrix composite has an encapsulation density between 1.80 and 2.50 grams per cubic centimeter, inclusive.

Embodiment 36 is the method of any one of embodiments 1 to 34, wherein the metal matrix composite has an encapsulation density of between 2.00 and 2.30 grams per cubic centimeter, inclusive.

Embodiment 37 is the method of any one of embodiments 1 to 34, wherein the metal matrix composite has an encapsulation density between 1.80 and 2.20 grams per cubic centimeter, inclusive.

Embodiment 38 is the method of any one of embodiments 1 to 33, wherein the metal comprises magnesium or an alloy thereof.

Embodiment 39 is the method of embodiment 38, wherein the metal matrix composite has an encapsulation density between 1.35 and 1.60 grams per cubic centimeter, inclusive.

Embodiment 40 is the method of embodiment 38 or embodiment 39, wherein the metal matrix composite has an encapsulation density between 1.55 and 1.60 grams per cubic centimeter, inclusive.

Embodiment 41 is the method of embodiment 38 or embodiment 39, wherein the metal matrix composite has an encapsulation density between 1.35 and 1.50 grams per cubic centimeter, inclusive.

Embodiment 42 is the method of any one of embodiments 1 to 41, wherein the metal matrix composite exhibits yield strength prior to failure in a tensile test.

Embodiment 43 is the method of any one of embodiments 1 to 42, wherein the metal is present in an amount between 50% and 95% by weight of the metal matrix composite, inclusive.

Embodiment 44 is the method of any one of embodiments 1 to 43, wherein the plurality of inorganic particles is present in an amount between 2% and 50% by weight of the metal matrix composite, inclusive. exist.

Embodiment 45 is the method of any one of embodiments 1 to 44, wherein the plurality of discontinuous fibers is between 2% and 25% by weight of the metal matrix composite, inclusive. Quantity exists.

Embodiment 46 is the method of any one of embodiments 1 to 45, wherein the plurality of inorganic particles and the plurality of discontinuous fibers are present in an amount between 5% and 50% by weight of the metal matrix composite Quantitative combinations in between and inclusive exist.

Embodiment 47 is the method of any one of embodiments 1 to 46, wherein the packing density of the inorganic particles is at least 40% less than a density of the metal.

Embodiment 48 is the metal matrix composite of any one of Embodiments 1 to 47, wherein the packing density of the inorganic particles is at least 50% less than a density of the metal.

Embodiment 49 is the metal matrix composite of any one of Embodiments 1 to 48, wherein the metal matrix composite consists essentially of the metal; the plurality of inorganic particles; and the plurality of discontinuous fiber composition.

Example

These examples are for illustrative purposes only, and are not intended to unduly limit the scope of the appended claims. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. At the very least, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques

Summary of materials

All parts, percentages, ratios, etc. in the examples, as well as in the remainder of the specification, are by weight unless otherwise indicated. Table 1 provides descriptions and sources of materials used in the following examples:

Table 1: List of materials

Test method 1: Three-point bending test

A three-point bend test was used to determine stress and strain in metal matrix composites. In the three-point bend test, the sample is placed longitudinally between two cylindrical supports spaced 32 millimeters (mm) apart. A third load-loading cylinder, suspended from the load cell of the testing apparatus, is lowered to contact the sample at its midpoint. The sample was loaded through an intermediate load-loading cylinder using a software-controlled load frame supplied by MTS Systems Corporation (Eden Prairie, MN) equipped with a 100 kilonewton (KN) load cell. center of the load. For each time point, the system measures the force applied to the sample and the displacement of the intermediate load-loaded cylinder from its starting position. These values were converted to stress and strain, respectively, using standard force equations.

Test Method 2: Acoustic Dispersion Method

To uniformly disperse the filler material(s) in the metal, all materials were poured into a 50 milliliter (mL) glass vial, which was then capped tightly. Next, the vial was loaded in a Resodyn LabRAM acoustic mixer (Resodyn Corporation, Butte, MT) and shaken at 70% intensity using acoustic frequency tuning for 3 minutes, after which point it was tapped against a hard surface 3-5 times to allow all material to settle to the bottom of the vial.

Test Method 3: Ion Leaching Test

A 100 g sample of glass bubbles was stirred with 1000 g deionized (DI) water in a sonicator for approximately 2 hours. The glass bubbles were then separated from the DI water by centrifugation at 10,000 revolutions per minute (rpm) for 10 minutes. The ion concentration in the resulting leach solution was measured by ion chromatography. Individual calibration curves for each ion were prepared by plotting the area of each ion in the standard against its concentration in the standard. The concentration of each ion leached from the sample was determined using the measured area of each ion. Discrimination of each ion is achieved by retaining matches only.

Test Method 4: Manual Dispersion Method

To manually disperse the filler material(s) in the metal, all materials are poured into a 50 milliliter (mL) glass vial, which is then tightly capped. Next, the vial was manually shaken for 30 seconds, after which time it was tapped against a hard surface 3-5 times to allow all material to settle at the bottom of the vial.

Preparation Example 1

The amounts of each material listed in Table 2 below were mixed and placed in fused silica crucibles. The mixture was then heated in a furnace at 2,320 degrees Fahrenheit (1,271 degrees Celsius) for four hours. Next, the material is cooled to room temperature (eg, about 23 degrees Celsius). The material was chiseled from the crucible and crushed into frit particles by a disc mill (BICO Inc., Burbank, CA). The largest dimension of the frit is less than 5 millimeters (mm). The frit particles were then jet milled using a jet mill (Hosokawa Alpine, Augsburg, Germany) to a powder with a particle size mass median diameter (D50) of 20 micrometers (μm). 1000 g of powder were then mixed with 1100 g of water, 2% by weight of additional boric acid and 0.3% by weight of sulfur from zinc sulfate and 1% by weight of CMC, each based on the total weight of the glass powder. The slurry was made to have a total solids of 48% by weight. The water/glass frit powder slurry was ground to a primary particle size of D50 of 1.4 μm by a LabStar Mill (NETZSCH Premier Technologies, LLC, Exton, PA). The slurry from milling is spray dried to form agglomerated feed particles. Glass bubbles were generated from the spray-dried feed by a natural gas flame. The total glass bubble density and flame conditions are listed in Table 3 below. The resulting bubbles had a D5 of 7 microns, a D50 of 35 microns and a D90 of 60 microns.

Table 2: Materials and amounts (grams) used for mixing and melting.

Table 3: Flame formation conditions and glass bubble density.

Table 4: Ion Chromatography Results.

Comparative example 1

10 grams (g) of Al 1-511 powder was poured into a circular graphite mold with an inner diameter of 1.5 inches (3.81 centimeters). The Al 1-511 powder was sintered by loading the mold into a HP50-7010 Thermal Press (Thermal Technology LLC, Santa Rosa, CA) and pumping the unit to vacuum. The mold was heated from room temperature at 25 degrees Celsius/minute (deg C/min) to 600 degrees Celsius and held at 600 degrees Celsius for 15 minutes (min). After the 15 min temperature hold, a force of 640 kilograms (kg) (800 pounds per square inch of pressure for a mold of this size) was applied at 600 degrees Celsius for 1 hour (hr). The pressure was then released, the chamber was flooded with nitrogen, and the mold furnace was allowed to cool back to room temperature. The dimensions of the resulting sintered disk were measured as well as its mass to calculate a bulk density of 1.91 grams per cubic centimeter (g/cc), which is 29% lower than fully dense pure aluminum. A strip having a width of approximately 0.5 inches (1.27 centimeters) and a length of 1.5 inches (3.81 centimeters) was cut from the middle of the disc and subjected to the three point bend test described above. The sample had a maximum tensile strength of 31 megapascals (MPa), giving it a strength to density ratio of 16. The results are shown in Table 5 below.

Comparative example 2

10 g of Al 1-511 powder and 1 g of glass bubbles were mixed by the above manual dispersion method, and the mixture was poured into the same graphite mold as Comparative Example 1. The device was then subjected to the same sintering procedure as described in Comparative Example 1 above. The resulting sintered disk had a density of 1.58 g/cc. The results of the three-point bend test are shown in Table 5 below and in FIG. 2 .

Comparative example 3

10 g of Al 1-511 powder and 1 g of ceramic fiber were mixed by the above manual dispersion method, and the mixture was poured into the same graphite mold as in Comparative Examples 1 and 2. The device was then subjected to the same sintering procedure as described in Comparative Example 1 above. The resulting disc had a density of 2.11 g/cc. The results of the three-point bend test are shown in Table 5 below and in FIG. 2 .

Comparative example 4

9 g of Al 1-511 powder, 0.3 g of glass bubbles, and 1.7 g of ceramic fibers were mixed loosely, and the mixture was poured into the same graphite mold as in Comparative Examples 1-3. The device was then subjected to the same sintering procedure as described in Comparative Example 1 above. The resulting disc had a density of 1.72 g/cc. The results of the three-point bend test are shown in Table 5 below and in FIG. 2 .

Example 5

9 g of Al 1-511 powder, 0.3 g of glass bubbles, and 1.7 g of ceramic fibers were mixed by the above manual dispersion method, and the mixture was poured into the same graphite mold as in Comparative Examples 1-4. The device was then subjected to the same sintering procedure as described in Comparative Example 1 above. The resulting disc had a density of 1.83 g/cc. The results of the three point bend test are shown in Table 5 below.

Example 6

10 g of Al powder, 0.5 g of glass bubbles, and 0.5 g of fiber were mixed by the above-mentioned manual dispersion method, and the mixture was poured into the same graphite mold as in Comparative Examples 1-4 and Example 5. The device was then subjected to the same sintering procedure as described in Comparative Example 1 above. The resulting disc had a density of 1.71 g/cc. The results of the three point bend test are shown in Table 5 below.

Example 7

8 g of Al 1-511 powder, 0.45 g of glass bubbles, and 2.55 g of ceramic fibers were mixed by the above manual dispersion method, and the mixture was poured into the same graphite mold as in Comparative Examples 1-4 and Examples 5-6. The device was then subjected to the same sintering procedure as described in Comparative Example 1 above. The resulting disc had a density of 1.78 g/cc. The results of the three point bend test are shown in Table 5 below.

Example 8

7 g of Al 1-511 powder, 0.6 g of glass bubbles, and 3.4 g of ceramic fibers were mixed by the above manual dispersion method, and the mixture was poured into the same graphite mold as in Comparative Examples 1-4 and Examples 5-7. The device was then subjected to the same sintering procedure as described in Comparative Example 1 above. The resulting disc had a density of 1.63 g/cc. The results of the three point bend test are shown in Table 5 below.

Table 5 :

Comparative Example 9

10.8 grams (g) of Al 6063 powder were poured into a circular graphite mold having an inner diameter of 1.575 inches (4.00 centimeters). The Al 6063 powder was sintered as follows: the mold was loaded into a Toshiba Machine GMP-411VA glass molding machine (Toshiba Machine Co., Numazu-shi, Japan), and the unit was It was flushed with nitrogen for 60 seconds and then pumped down to vacuum. The mold was heated from 40 degrees Celsius to 600 degrees Celsius at 28 degrees Celsius/minute (deg C/min). Once the mold reached 600 degrees Celsius, it was held at that temperature while gradually increasing the force on the mold from zero applied force to 21,000 Newtons (2400 psi (or 16.55 MPa) pressure for a mold of this size). The gradual increase in force occurred approximately linearly over the course of 20 minutes. Once a full force of 21,000 N is reached, the mold is held at 600 degrees Celsius for 1 hour. The pressure is then released and the mold furnace is allowed to cool back to room temperature. The dimensions of the resulting sintered disk were measured as well as its mass to calculate an encapsulation density of 2.51 grams per cubic centimeter (g/cc), which is 7% lower than fully dense aluminum 6063. A strip having a width of approximately 0.5 inches (1.27 centimeters) and a length of 1.5 inches (3.81 centimeters) was cut from the middle of the disc and subjected to the three point bend test described above. The sample had an ultimate tensile strength of 203 megapascals (MPa). The results are shown in Table 6 below and in FIG. 3 .

Comparative Example 10

8.64 g of Al 6063 powder and 0.48 g of alumina powder were mixed by the above-mentioned acoustic dispersion method, and the mixture was poured into the same graphite mold as in Comparative Example 9. The device was then subjected to the same sintering procedure as described in Comparative Example 9 above. The resulting sintered disk had a packing density of 2.34 g/cc. The results of the three-point bend test are shown in Table 6 below and in FIG. 3 .

Comparative Example 11

9.72g of Al 6063 powder and 1.56g of ceramic fiber were mixed by the above-mentioned acoustic dispersion method, and the mixture was poured into the same graphite mold as in Comparative Examples 9-10. The device was then subjected to the same sintering procedure as described in Comparative Example 9 above. The resulting disc had a packing density of 2.65 g/cc. The results of the three-point bend test are shown in Table 6 below and in FIG. 3 .

Example 12

7.56g of Al 6063 powder, 0.48g of alumina powder, and 1.56g of ceramic fiber were mixed by the above-mentioned acoustic dispersion method, and the mixture was poured into the same graphite mold as in Comparative Examples 9-11. The device was then subjected to the same sintering procedure as described in Comparative Example 9 above. The resulting disc had a packing density of 2.45 g/cc. The results of the three-point bend test are shown in Table 6 below and in FIG. 3 .

Example 13

5.4 g of Al 6063 powder, 0.96 g of alumina powder, and 1.56 g of ceramic fiber were mixed by the above-mentioned acoustic dispersion method, and the mixture was poured into the same graphite mold as in Comparative Examples 9-11 and Example 12. The device was then subjected to the same sintering procedure as described in Comparative Example 9 above. The resulting disk had a packing density of 2.11 g/cc. The results of the three-point bend test are shown in Table 6 below and in FIG. 3 .

Example 14

5.4g of Al 6063 powder, 0.96g of alumina powder, and 1.56g of ceramic fiber were mixed by the above-mentioned acoustic dispersion method, and the mixture was poured into the same graphite mold as in Comparative Examples 9-11 and Examples 12-13. The mold was loaded into a Toshiba Machine GMP-411VA Glass Molding Machine (Toshiba Machine Co., Numazu, Japan), and the apparatus was flooded with nitrogen for 60 seconds and then pumped to vacuum. Heat the mold from 40°C to 630°C at 30deg C/min. Once the mold reached 630 degrees Celsius, it was held at that temperature while gradually increasing the force on the mold from zero applied force to 34,664 Newtons (a pressure of 4000 psi (or 27.58 MPa) for a mold of this size). The gradual increase in force occurred approximately linearly over the course of 20 minutes. Once a full force of 34,664N is reached, the mold is held at 630 degrees Celsius for 1 hour. The pressure is then released and the mold furnace is allowed to cool back to room temperature. The resulting disc had a packing density of 2.19 g/cc. The results of the three-point bend test are shown in Table 6 below and in FIG. 3 .

Table 6: Composition and mechanical properties of the examples .

Comparative Example 15

10.8 grams (g) of Al 6063 powder were poured into a circular graphite mold having an inner diameter of 1.575 inches (4.00 centimeters). The Al 6063 powder was sintered by loading the mold into a Toshiba Machine GMP-411VA glass molding machine (Toshiba Machine, Numazu, Japan) and filling the apparatus with nitrogen for 60 seconds, then pumping it to vacuum. The mold was heated from 40 degrees Celsius to 615 degrees Celsius at 28 degrees Celsius/minute (deg C/min). Once the mold reached 615 degrees Celsius, it was held at that temperature while gradually increasing the force on the mold from zero force to 21,000 Newtons (1600 psi pressure for a mold of this size). The gradual increase in force occurred approximately linearly over the course of 20 minutes. Once a full force of 21,000 N is reached, the mold is held at 600 degrees Celsius for 1 hour. The pressure is then released and the mold furnace is allowed to cool back to room temperature. The dimensions of the resulting sintered disk were measured as well as its mass to calculate an encapsulation density of 2.51 grams per cubic centimeter (g/cc), which is 7% lower than fully dense aluminum 6063. A strip having a width of approximately 0.5 inches (1.27 centimeters) and a length of 1.575 inches (4.00 centimeters) was cut from the middle of the disc and subjected to the three point bend test described above. The sample had an ultimate tensile strength of 203 megapascals (MPa). The results are shown in Table 7 and Figure 4 below.

Example 16

5.4 g of Al 1-511 powder, 0.96 g of glass bubbles, and 0.78 g of ceramic fibers were mixed by the above-mentioned acoustic dispersion method, and the mixture was poured into the same graphite mold as in Comparative Example 15. The mold was loaded into a Toshiba Machine GMP-411VA Glass Molding Machine (Toshiba Machine Co., Numazu, Japan), and the apparatus was flooded with nitrogen for 60 seconds and then pumped to vacuum. The mold was heated from 40 degrees Celsius to 615 degrees Celsius at 30 degrees Celsius/minute (deg C/min). Once the mold reached 615 degrees Celsius, it was held at that temperature while gradually increasing the force on the mold from zero force to 13,954 Newtons (1600 psi pressure for a mold of this size). The gradual increase in force occurred approximately linearly over the course of 20 minutes. Once a full force of 13,954 N is reached, the mold is held at 615 degrees Celsius for 1 hour. The pressure is then released and the mold furnace is allowed to cool back to room temperature. The resulting disc had a packing density of 1.93 g/cc. The results of the three-point bend test are shown in Table 7 below and in FIG. 4 .

Example 17

5.4g of Al 1-511 powder, 0.96g of glass bubbles, and 0.78g of ceramic fibers were mixed by the acoustic dispersion method described above, and the mixture was poured into the same graphite mold as in Example 16. The device was then subjected to the same sintering procedure as described in Example 16 above. The resulting disc had a packing density of 1.91 g/cc. The results of the three-point bend test are shown in Table 7 below and in FIG. 4 .

Example 18

5.4g of Al 1-511 powder, 0.96g of Lightstar 106 floating beads, and 0.78g of ceramic fibers were mixed by the acoustic dispersion method described above, and the mixture was poured into the same graphite mold as in Example 16. The device was then subjected to the same sintering procedure as described in Example 16 above. The resulting disc had a packing density of 1.93 g/cc. The results of the three-point bend test are shown in Table 7 below and in FIG. 4 .

Example 19

5.4g of Al 1-511 powder, 0.96g of High Alumina 106 floating beads and 0.78g of ceramic fiber were mixed by the above acoustic dispersion method, and the mixture was poured into the same graphite mold as in Example 16. The device was then subjected to the same sintering procedure as described in Example 16 above. The resulting disc had a packing density of 1.95 g/cc. The results of the three-point bend test are shown in Table 7 below and in FIG. 4 .

Example 20

5.4g of Al 1100 powder, 0.96g of Econostar 106 floating beads, and 0.78g of ceramic fibers were mixed by the acoustic dispersion method described above, and the mixture was poured into the same graphite mold as in Example 16. The device was then subjected to the same sintering procedure as described in Example 16 above. The resulting disc had a packing density of 1.93 g/cc. The results of the three-point bend test are shown in Table 7 below and in FIG. 4 .

Table 7: Composition and mechanical properties of the examples .

Example 21

5.4 g of Al 1-511 powder, 0.96 g of partially sintered silicon carbide agglomerate particles, and 0.78 g of ceramic fibers were mixed by the acoustic dispersion method described above, and the mixture was poured into the same graphite mold as in Example 16. The device was then subjected to the same sintering procedure as described in Example 16 above. The resulting disc had a pack density of 2.28 g/cc, an ultimate tensile strength of 190 MPa, and a strain to failure of 3.4%. The results of the three-point bending test are shown in FIG. 5 .

Example 22

5.94g Al-131 powder, 0.96g Lightstar 106 floating beads and 0.78g ceramic fiber were mixed by the above acoustic dispersion method and the mixture was poured into the same graphite mold as in Example 16. The device was then subjected to the same sintering procedure as described in Example 16 above. The resulting disc had a packing density of 1.98 g/cc. The results of the three-point bend test are shown in Table 8 below and in FIG. 6 .

Example 23

7.56g of Al 1-131 powder, 0.6g of Lightstar 106 floating beads, and 0.78g of ceramic fibers were mixed by the acoustic dispersion method described above, and the mixture was poured into the same graphite mold as in Example 16. The device was then subjected to the same sintering procedure as described in Example 16 above. The resulting disc had a packing density of 2.21 g/cc. The results of the three-point bending test are shown in Table 8 and FIG. 6 .

Example 24

7.02g of Al 1-131 powder, 0.72g of Lightstar 106 floating beads, and 0.78g of ceramic fibers were mixed by the acoustic dispersion method described above, and the mixture was poured into the same graphite mold as in Example 16. The device was then subjected to the same sintering procedure as described in Example 16 above. The resulting disc had a packing density of 2.12 g/cc. The results of the three-point bending test are shown in Table 8 and FIG. 6 .

Example 25

7.02g of Al powder, 0.72g of Lightstar 106 floating beads, and 0.78g of ceramic fibers were mixed by the acoustic dispersion method described above, and the mixture was poured into the same graphite mold as in Example 16. The device was then subjected to the same sintering procedure as described in Example 16 above. The resulting disc had a packing density of 2.00 g/cc. The results of the three-point bending test are shown in Table 8 and FIG. 6 .

Table 8: Composition and mechanical properties of the examples .

Example 26

5.94g of Al 1-131 powder, 0.84g of Lightstar 106 floating beads, and 1.016g of glass fiber were mixed by the acoustic dispersion method described above, and the mixture was poured into the same graphite mold as in Example 16. The device was then subjected to the same sintering procedure as described in Example 16 above. The resulting disc had a pack density of 2.00 g/cc, an ultimate tensile strength of 159 MPa, and a strain to failure of 1.8%. The results of the three-point bending test are shown in FIG. 7 .

Although the specification has described certain exemplary embodiments in detail, it should be understood that changes, modifications and equivalents of these embodiments can be easily conceived by those skilled in the art after understanding the above contents. Furthermore, all publications and patents cited herein are herein incorporated by reference in their entirety as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. Various exemplary embodiments have been described. These and other implementations are within the scope of the following claims.

Claims (14)

1. A method for preparing porous metal matrix composite, said method comprising: a. mixing the metal powder, the plurality of inorganic particles, and the plurality of discontinuous fibers to form a mixture; and b. Sintering the mixture to form the porous metal matrix composite. 2. The method of claim 1, wherein the mixture is sintered in a mold. 3. The method of claim 1 or claim 2, wherein the sintering is carried out at a temperature between 250 degrees Celsius and 1,000 degrees Celsius, inclusive. 4. The method of any one of claims 1 to 3, wherein the sintering includes applying pressure. 5. The method of claim 4, wherein the sintering is carried out at a pressure comprised between 4 MPa and 200 MPa, inclusive. 6. The method according to any one of claims 1 to 5, wherein the mixing is carried out using an acoustic mixer, a mechanical mixer or a tumbler. 7. The method of any one of claims 1 to 6, wherein the mixture comprises the inorganic particles and the discontinuous fibers dispersed in the metal powder. 8. The method of any one of claims 1 to 7, wherein the plurality of inorganic particles comprises porous particles comprising porous metal oxide particles, porous metal hydroxide particles, porous metal carbonate Salt, porous carbon particles, porous silica particles, porous dehydrated aluminosilicate particles, porous dehydrated metal hydrate particles, zeolite particles, porous glass particles, expanded perlite particles, expanded vermiculite particles, porous sodium silicate particles, Engineered porous ceramic particles, agglomerates of non-porous primary particles, or combinations thereof. 9. The method of any one of claims 1 to 7, wherein the plurality of inorganic particles comprises ceramic or glass bubbles. 10. The method of any one of claims 1 to 9, wherein the plurality of discontinuous fibers comprises glass, alumina, aluminosilicate, carbon, basalt, or combinations thereof. 11. The method of any one of claims 1 to 10, wherein the metal comprises aluminium, magnesium, an aluminum alloy or a magnesium alloy. 12. The method of any one of claims 1 to 11, wherein the metal matrix composite has an encapsulation density that is at least 8% less than that of the metal and is capable of withstanding a 1% strain before fracture. 13. The method of claim 12, wherein the metal matrix composite is capable of withstanding 2% strain before fracture. 14. The method of any one of claims 1 to 13, wherein the metal matrix composite has a yield strength of 50 MPa or greater.