EP3265596A1

EP3265596A1 - Metal matrix composite granules and methods of making and using the same

Info

Publication number: EP3265596A1
Application number: EP16718531.3A
Authority: EP
Inventors: Andrew D. Tarrant; Nicholas David TRICKER; Jeffrey R. Campbell; Nicholas J. HONEY; Charles Pokross; Tahsina SMITH
Original assignee: Materion Corp
Current assignee: Materion Corp
Priority date: 2015-03-03
Filing date: 2016-03-03
Publication date: 2018-01-10
Also published as: US20160303650A1; WO2016141160A1

Abstract

Metal matrix composite granules are disclosed comprising a ceramic phase dispersed in a matrix phase. The matrix phase includes aluminum or an aluminum alloy. The granules have an average particle size in the range of from about 100 µm to about 1,000 µm. Also disclosed are methods for producing the granules or articles or processes for using the granules to produce various articles, among other things.

Description

METAL MATRIX COMPOSITE GRANULES AND METHODS OF MAKING AND

USING THE SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 62/127,444, filed on March 3, 2015. That application is hereby fully incorporated by reference herein.

BACKGROUND

[0002] The present disclosure relates to metal matrix composite granules including a ceramic phase dispersed in a matrix phase. The matrix phase includes aluminum or an aluminum alloy. The granules are a metal composite powder having an average particle size in the range of from about 100 pm to about 1 ,000 pm. The disclosure also relates to methods for producing the granules and methods for using the compositions to produce articles, among other things.

[0003] Metal matrix composites are composite materials including a metal matrix and a reinforcing material (e.g., a ceramic material or an organic compound) dispersed in the metal matrix. The metal matrix phase is typically continuous whereas the reinforcing dispersed phase is typically discontinuous. The reinforcing material may serve a structural function and/or change one or more properties of the material. Metal matrix composites can provide combinations of mechanical and physical properties that cannot be achieved through conventional materials or process techniques. These property combinations have made metal matrix composites particularly useful in transport industries where weight, strength, and stiffness are important (e.g., the aerospace and automotive industries).

[0004] Powder metallurgy is a process by which powdered materials are compacted into a desired shape and sintered to produce desired articles. Powder metallurgy allows for a faster quenching rate of the metal from the melt which typically results in smaller grain sized, increased solid solubility of most solute elements, and reduced segregation of intermetallic phases. These results may lead to beneficial properties in the produced articles, such as high strength at normal and elevated temperatures, high modulus values, good fracture toughness, low fatigue crack growth rate, and high resistance to stress corrosion cracking.

[0005] Known compositions and methods for producing articles containing metal matrix composites have several deficiencies. Achieving a desired distribution of the reinforcing material throughout the metal matrix can be difficult. Long and expensive degassing procedures may be required. Handling hazards and difficulties such as explosions, clogging, and rat-holing may also occur. A large number of process steps may be required to make parts and this may also result in higher yield losses at each process stage. Compaction of granules provides a direct, simple and cost-effective route to make parts (herein referred to as direct powder processing). Compaction may lead to articles that are not fully dense and have lower properties. An unacceptable level of oxides may form in powder metallurgy processes, reducing the properties of the manufactured articles.

[0006] It would be desirable to provide compositions and methods for producing articles containing metal matrix composites via powder metallurgy that overcome the aforementioned deficiencies allowing for efficient, safe, and cost-effective manufacturing.

BRIEF DESCRIPTION

[0007] The present disclosure relates to compositions that include metal matrix composite granules, the granules including a ceramic phase dispersed in a matrix phase. The matrix phase includes aluminum or an aluminum alloy. The metal matrix composite granules have an average particle size in the range of from about 100 pm to about 1 ,000 pm. The disclosure also relates to methods for producing the granules and methods for using the compositions.

[0008] Disclosed in various embodiments are compositions including granules of a metal matrix composite. The metal matrix composite includes a ceramic dispersed phase in an aluminum or aluminum alloy matrix. The granules have an average particle size of from about 100 m to about 1 ,000 pm.

[0009] In some embodiments, the granules have an average particle size of from about 200 pm to about 800 pm. [0010] The ceramic dispersed phase may include at least one ceramic material selected from the group consisting of carbides, oxides, silicides, borides, and nitrides.

[0011] In some embodiments, the ceramic dispersed phase comprises at least one ceramic material selected from the group consisting of silicon carbide, titanium carbide, boron carbide, silicon nitride, titanium nitride, zirconium oxide, aluminum oxide, aluminum nitride, and titanium oxide.

[0012] The aluminum alloy may include at least one element selected from the group consisting of chromium, copper, lithium, magnesium, manganese, nickel, iron, vanadium, zinc, and silicon.

[0013] In some embodiments, the aluminum alloy includes from about 91 .2 wt% to about 94.7 wt% aluminum, from about 3.8 wt% to about 4.9 wt% copper, from about 1 .2 wt% to about 1.8 wt% magnesium, and from about 0.3 wt% to about 0.9 wt% manganese.

[0014] The aluminum alloy may include from about 95.8 wt% to about 98.6 wt% aluminum, from about 0.8 wt% to about 1 .2 wt% magnesium, and from about 0.4 wt% to about 0.8 wt% silicon. In additional embodiments, these aluminum alloys can also include from about 0.15 wt% to about 0.4 wt% copper, and 0.04 wt% to about 0.35 wt% chromium.

[0015] In some embodiments, the granules comprise from about 1 vol% to about 45 vol% of the ceramic dispersed phase, including from about 1 vol% to about 35 vol% and from about 15 vol% to about 30 vol%.

[0016] Disclosed in other embodiments are methods for producing granules of a metal matrix composite. The methods include high energy mixing metal particles and ceramic particles to form the granules. The granules include a dispersed phase formed from the ceramic particles and a matrix phase formed from the metal particles. The granules have an average particle size of from about 100 pm to about 1 ,000 pm. The metal particles comprise aluminum or an aluminum alloy, which are reinforced in the granules with the ceramic particles.

[0017] The granules may have an average particle size of from about 200 pm to about 800 pm. [0018] In some embodiments, the ceramic particles include at least one ceramic material selected from the group consisting of carbides, oxides, silicides, borides, and nitrides.

[0019] The ceramic particles may include at least one ceramic material selected from the group consisting of silicon carbide, titanium carbide, boron carbide, silicon nitride, titanium nitride, zirconium oxide, aluminum oxide, aluminum nitride, and titanium oxide.

[0020] In some embodiments, the ceramic particles have an average particle size in the range of from about 0.2 pm to about 10 pm, including from about 1 .5 pm to about 3.5 pm. The size of the ceramic reinforcement particles can be selected depending on the strength and mechanical properties required.

[0021] The ceramic particles may have an average particle size in the range of from about 1 m to about 4 pm, including from about 2 pm to about 3 pm. Alternatively, the ceramic particles may have an average particle size in the range of from about 0.2 pm to about 0.4 pm or from about 0.5 pm to about 0.9 pm.

[0022] In some embodiments, the metal particles, prior to manufacture of the granules, have an average particle size in the range of from about 5 pm to about 150 pm.

[0023] The metal particles may have an average particle size in the range of from about 15 pm to about 75 pm.

[0024] In some embodiments, the metal particles have an average particle size in the range of from about 20 pm to about 30 pm.

[0025] The granules may include from about 1 vol% to about 45 vol% of the dispersed phase.

[0026] Disclosed in further embodiments are methods for producing an article. The methods include densifying a preform. The preform includes granules of a metal matrix composite. The metal matrix composite includes a ceramic dispersed phase in an aluminum or aluminum alloy matrix. The granules have an average particle size of from about 100 pm to about 1 ,000 pm. Also disclosed are the various articles produced by these processes.

[0027] In some embodiments, the granules comprise from about 1 vol% to about 45 vol% of the dispersed phase. [0028] These and other non-limiting characteristics of the disclosure are more particularly disclosed below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following is a brief description of the drawings, which are presented for the purposes of illustrating the exemplary embodiments disclosed herein and not for the purposes of limiting the same.

[0030] FIG. 1 is a flow chart illustrating an exemplary method for forming metal matrix composite granules in accordance with some embodiments of the present disclosure.

[0031] FIG. 2 is an optical image of the microstructure of exemplary granules of the present disclosure.

[0032] FIG. 3 is a flow chart illustrating an exemplary method for forming an article using metal matrix composite granules in accordance with some embodiments of the present disclosure.

[0033] FIG. 4 is an exploded, cross-sectional view of an apparatus that can be used to perform some exemplary methods of the present disclosure.

[0034] FIG. 5 is a photograph illustrating a side-by-side comparison of a cold compact preform and a hot forged preform (at 125 tons) of the present disclosure.

[0035] FIG. 6 is a photograph illustrating a side-by-side comparison of a cold compact preform and a hot forged article (at 150 tons) of the present disclosure.

[0036] FIG. 7 is a photograph illustrating a side-by-side comparison of a cold compact preform and a hot forged article (at 200 tons) of the present disclosure.

[0037] FIG. 8 is an optical image of the microstructure of a hot forged article (at 125 tons) of the present disclosure.

[0038] FIGS. 9A and 9B are photographs of discs that have been open die forged according to embodiments of the present disclosure.

[0039] FIG. 10 is another flowchart showing process steps in accordance with the methods of the present disclosure

[0040] FIG. 11 is a set of pictures showing various intermediate products when using hot forging methods. [0041] FIG. 12 is a set of pictures showing various intermediate products when using hot extrusion methods.

DETAILED DESCRIPTION

[0042] A more complete understanding of the components, processes and apparatuses disclosed herein can be obtained by reference to the accompanying drawings. These figures are merely schematic representations based on convenience and the ease of demonstrating the present disclosure, and are, therefore, not intended to indicate relative size and dimensions of the devices or components thereof and/or to define or limit the scope of the exemplary embodiments.

[0043] Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure. In the drawings and the following description below, it is to be understood that like numeric designations refer to components of like function.

[0044] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0045] As used in the specification and in the claims, the term "comprising" may include the embodiments "consisting of" and "consisting essentially of." The terms "comprise(s)," "include(s)," "having," "has," "can," "contain(s)," and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that require the presence of the named components/steps and permit the presence of other components/steps. However, such description should be construed as also describing compositions or processes as "consisting of" and "consisting essentially of" the enumerated components/steps, which allows the presence of only the named components/steps, along with any impurities that might result therefrom, and excludes other components/steps.

[0046] Numerical values in the specification and claims of this application should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values which differ from the stated value by less than the experimental error of conventional measurement technique of the type described in the present application to determine the value.

[0047] All ranges disclosed herein are inclusive of the recited endpoint and independently combinable (for example, the range of "from 2 to 10" is inclusive of the endpoints, 2 and 10, and all the intermediate values).

[0048] The term "about" can be used to include any numerical value that can vary without changing the basic function of that value. When used with a range, "about" also discloses the range defined by the absolute values of the two endpoints, e.g. "about 2 to about 4" also discloses the range "from 2 to 4." The term "about" may refer to plus or minus 10% of the indicated number.

[0049] The present disclosure refers to granules having an average particle size. The average particle size for granules is defined as the particle diameter at which a cumulative percentage of 50% by weight of the granules are attained. In other words, 50 wt% of the granules have a diameter above the average particle size, and 50 wt% of the granules have a diameter below the average particle size.

[0050] The present disclosure also refers to particles as having an average particle size. The average particle size for particles is defined as the particle diameter at which a cumulative percentage of 50% by volume of the particles are attained. In other words, 50 vol% of the particles have a diameter above the average particle size, and 50 vol% of the particles have a diameter below the average particle size.

[0051] The present disclosure relates to metal matrix composite granules including a ceramic phase dispersed in a matrix phase. The matrix phase includes aluminum or an aluminum alloy. The granules have an average particle size in the range of from about 100 pm to about 1 ,000 pm. The disclosure also relates to methods for producing the granules and methods for using compositions containing such granules.

[0052] The compositions of the present disclosure allow metal composite components to be made using cost-effective, high-yield direct powder processes. This minimizes the number of process steps from raw material to the final article shape. The distribution of the ceramic particles is achieved at the granule stage which is important for product quality assurance. [0053] The granules of the present disclosure have lower surface area to volume ratios compared to powders. The increased granule size reduces the potential for surface oxidation and makes compaction easier. Fully-dense compacts can be produced with lower deformation (e.g., shear deformation) and at reduced temperatures and/or pressures.

[0054] The relatively large granule size also provides additional processing and handling benefits. For example, explosion hazards are reduced in the industrial environment; and enhanced aid flow characteristics can be achieve to avoid clogging and rat-holing in feeder equipment. The particle size of the granules may be controlled using sieves.

[0055] The methods of the present disclosure may be performed in a dry, inert atmosphere. Processing in such an atmosphere produces an effective degassing procedure and reduces the need for long and expensive degassing procedures later on. Direct powder processing also reduces the number of process steps required to make parts and allows for higher yield. In direct powder processing, powder is compacted and shaped directly into the desired part, instead of being remelted into a molten form and then shaped into the desired part. Warm degass procedures can be applied after initial powder compaction to remove any moisture from powder surfaces.

[0056] FIG. 1 is a flowchart showing a general method 100 for forming metal matrix composite granules of the present disclosure. The method includes providing metal particles 105 and providing ceramic particles 110 to a high energy mixing stage 120. In the mixing stage 120, metal matrix composite granules are formed. The granules are then sorted 130 to provide a composition of granules having an average size in the range of from about 100 pm to about 1 ,000 pm. The granules may have an average particle size in the range of from about 200 pm to about 800 m, including from about 300 to about 700 pm and from about 400 to about 600 pm.

[0057] The high energy mixing 120 may be performed using one or more of ball milling, teemer mills, attritors, rotary mills, and granulators.

[0058] The metal particles 105 include aluminum or an aluminum alloy. The aluminum alloy may include at least one element selected from chromium, copper, lithium, magnesium, nickel, and silicon. It is noted that "aluminum," as used here, refers to aluminum with only impurities present, i.e. pure aluminum, whereas the term "aluminum alloy" is used to refer to alloys of aluminum with a significant amount of another element.

[0059] In some embodiments, the aluminum alloy is a 1000 series alloy (> 99 wt% aluminum), a 2000 series alloy (including copper as an alloying component), a 3000 series alloy (including manganese as an alloying component), a 4000 series alloy (including silicon as an alloying component), a 5000 series alloy (including magnesium as an alloying component), a 6000 series alloy (including magnesium and silicon as alloying components), a 7000 series alloy (including zinc as an alloying component), or an 8000 series alloy (e.g., aluminum-lithium alloys).

[0060] The metal particles may have an average particle size in the range of from about 5 pm to about 150 pm, including from about 15 pm to about 75 pm, about 20 pm to about 50 pm, from about 20 pm to about 40 pm, from about 20 pm to about 30 pm, and about 75 pm.

[0061] In some embodiments, the aluminum alloy includes from about 91 .2 wt% to about 94.7 wt% aluminum, from about 3.8 wt% to about 4.9 wt% copper, from about 1 .2 wt% to about 1.8 wt% magnesium, and from about 0.3 wt% to about 0.9 wt% manganese.

[0062] In other embodiments, the aluminum alloy includes from about 95.8 wt% to about 98.6 wt% aluminum, from about 0.8 wt% to about 1 .2 wt% magnesium, and from about 0.4 wt% to about 0.8 wt% silicon. In additional embodiments, these aluminum alloys can also include from about 0.15 wt% to about 0.4 wt% copper, and 0.04 wt% to about 0.35 wt% chromium.

[0063] The aluminum alloy may be 2009. The composition of 2009 aluminum alloy is as follows:

[0064] The aluminum alloy may be 2124. The composition of 2124 aluminum alloy is as follows:

[0065] The aluminum a of 2618 aluminum alloy is as follows:

[0066] The aluminum alloy may be 6061 . The composition of 6061 aluminum alloy is as follows:

[0067] The aluminum a of 6082 aluminum alloy is as follows:

[0068] The ceramic particles 110 include at least one material selected from carbides, oxides, silicides, borides, and nitrides. In some embodiments, the material is selected from silicon carbide, titanium carbide, boron carbide, silicon nitride, titanium nitride, zirconium oxide, aluminum oxide, aluminum nitride, and titanium oxide.

[0069] The ceramic particles may have an average particle size in the range of from about 0.1 pm to about 20 pm, including from about 0.2 pm to about 10 pm, and from about 1 m to about 4 pm. In other embodiments, the ceramic particles have an average particle size in the range of from about 0.2 pm to about 0.4 pm, or from about 0.5 pm to about 0.9 pm. [0070] The granules produced by the high energy mixing 120 may contain up to about 45 vol% of a ceramic phase dispersed in a metal matrix phase. In some embodiments, the granules include from about 1 vol% to about 35 vol% of the ceramic dispersed phase, including from about 5 to about 30 vol%, from about 10 to about 25 vol%, and about 20 vol%.

[0071] FIG. 2 is an optical image of a plurality of granules.

[0072] If necessary, the granules may be sorted 130 to obtain a composition having the desired grain size.

[0073] FIG. 3 is a flow chart illustrating an exemplary method 300 for forming an article using the granules. The method includes providing the granules 330; compacting the granules to make a preform 340; and then hot forging or hot extruding the preform 350

[0074] During compacting 340, the granules are cold compacted into a desired shape to make a preform. The cold compacting coalesces the particles and increases density. However, the preform is not close to fully dense. In particular embodiments, the cold compacting is performed using a tool diameter of about 50 mm to about 70 mm, with a load of about 80 tons to about 90 tons. In other embodiments, the cold compacting is performed using a tool diameter of about 50 mm to about 70 mm, with an exerted pressure of about 250 MPa to about 330 MPa. Of course, the tool diameter, exerted pressure, and load can be larger as well, as might occur in commercial production processes. The cold compacting can also be done by cold isostatic pressing, in which the granules are exposed to a high gas pressure in a high pressure containment vessel, to turn the granules into a compact solid, i.e. a billet. In either case, warm degass procedures can be applied after initial powder compaction to remove any moisture from powder surfaces.

[0075] Next, the preform is hot forged or hot extruded 350. The hot forging may be performed at a temperature in the range of from about 300 °C to about 600 °C, including from about 400 °C to about 500 °C, and about 450 °C.

[0076] FIG. 4 illustrates an exemplary apparatus 360 that may be used to compact the granules into the preform 365. The apparatus 360 includes a punch 361 , a pot die 362, and an ejector 363. A slug 364 may be placed upon the preform 365 during compacting 340. The slug 364 may be etched off after compacting/extruding. In some embodiments, the slug 364 is a copper can.

[0077] The articles (e.g., billets) formed from these methods may be used as inputs for further processing to form final articles.

[0078] FIG. 10 illustrates an exemplary method 700 in accordance with embodiments of the present disclosure. The method 700 includes providing raw materials (e.g., aluminum powder and silicon carbide particles 780); high energy mixing the raw materials to form granules 781 ; cold compacting 782 (e.g., via die compaction or cold isostatic pressing); hot compacting 783 (e.g., via forging or extruding); and finish forging or extruding 784.

[0079] FIG. 11 shows some pictures of the intermediate products at each step when hot forging 883 is used. A micrograph of the granules is labeled 885. The die compaction unit is labeled 886. The cold die compacted granules are labeled 887, while the granules after hot forging are labeled 888. The final forged disc is labeled 889

[0080] FIG. 12 shows some pictures of the intermediate products at each step when hot extruding 983 is used. A picture of the granules is labeled 990. A billet obtained after cold isostatic pressing is labeled 991. The billet is then hot extruded at 60 mm diameter, and a picture of the resulting bar is labeled 992. The bar is then die forged into a disc, which is labeled 993.

[0081] Non-limiting examples of final articles that the compositions, systems, and methods of the present disclosure can be used to produce include discs, pistons, con rods, and piston pins.

[0082] The following examples are provided to illustrate the compositions, articles, and methods of the present disclosure. The examples are merely illustrative and are not intended to limit the disclosure to the materials, conditions, or process parameters set forth therein. EXAMPLES

Example 1

Cold Compaction

[0083] Granules having the composition of AMC225XE (commercially available from Materion Corporation) were cold compacted using various tool diameters (from about 15 to about 60 mm) and loads (from about 30 to about 100 tons). AMC225XE includes silicon carbide particles dispersed in a matrix of aluminum alloy 2124. The results are provided in the table below.

Hot Forging

[0084] Next, a 60 mm diameter die was used to compact the samples from the 90 ton load. The preforms were hot forged at a temperature of 450°C. Experiments were performed with and without lubrication. However, the compacted samples from the unlubricated experiments could not be extracted.

[0085] Loads of 125 tons, 150 tons, and 200 tons were tested. The results are provided in the table below and in FIGS. 5-8.

[0086] FIG. 5 shows the cold preformed material 470 and hot forged article 475 of the 125 ton load test. FIG. 6 shows the cold preformed material 570 and hot forged article 575 of the 150 ton load test. FIG. 7 shows the cold preformed material 670 and hot forged article 675 of the 200 ton test. FIG. 8 is an optical image of the surface of the hot forged article 475 of FIG. 5.

Die Forging

[0087] The articles were subsequently die forged. FIG. 9A is a photograph of six pucks die forged from the 125 ton load test. FIG. 9B is a photograph of two pucks die forged from the 150 ton load test and one puck die forged from the 200 ton load test.

[0088] The present disclosure has been described with reference to exemplary embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the present disclosure be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

CLAIMS:

1 . A composition comprising granules of a metal matrix composite;

wherein the metal matrix composite comprises a ceramic dispersed phase in an aluminum or aluminum alloy matrix; and

wherein the granules have an average particle size of from about 100 pm to about 1 ,000 pm.

2. The composition of claim 1 , wherein the granules have an average particle size of from about 200 pm to about 800 pm.

3. The composition of claim 1 , wherein the ceramic dispersed phase comprises at least one ceramic material selected from the group consisting of carbides, oxides, silicides, borides, and nitrides.

4. The composition of claim 1 , wherein the ceramic dispersed phase comprises at least one ceramic material selected from the group consisting of silicon carbide, titanium carbide, boron carbide, silicon nitride, titanium nitride, zirconium oxide, aluminum oxide, aluminum nitride, and titanium oxide.

5. The composition of claim 1 , wherein the aluminum alloy further comprises at least one element selected from the group consisting of chromium, copper, lithium, magnesium, manganese, nickel, iron, vanadium, zinc, and silicon.

6. The composition of claim 1 , wherein the aluminum alloy comprises from about 91.2 wt% to about 94.7 wt% aluminum, from about 3.8 wt% to about 4.9 wt% copper, from about 1 .2 wt% to about 1 .8 wt% magnesium, and from about 0.3 wt% to about 0.9 wt% manganese.

7. The composition of claim 1 , wherein the aluminum alloy comprises from about 95.8 wt% to about 98.6 wt% aluminum, from about 0.8 wt% to about 1 .2 wt% magnesium, and from about 0.4 wt% to about 0.8 wt% silicon.

8. The composition of claim 1 , wherein the granules comprise from about 1 vol% to about 45 vol% of the ceramic dispersed phase.

9. A method for producing granules of a metal matrix composite, the method comprising:

high energy mixing metal particles and ceramic particles to form the granules;

wherein the granules comprise a dispersed phase formed from the ceramic particles and a matrix phase formed from the metal particles;

wherein the granules have an average particle size of from about 100 pm to about 1 ,000 pm; and

wherein the metal particles comprise aluminum or an aluminum alloy.

10. The method of claim 9, wherein the granules have an average particle size of from about 200 pm to about 800 pm.

1 1 . The method of claim 9, wherein the ceramic particles comprise at least one ceramic material selected from the group consisting of carbides, oxides, silicides, borides, and nitrides.

12. The method of claim 9, wherein the ceramic particles comprises at least one ceramic material selected from the group consisting of silicon carbide, titanium carbide, boron carbide, silicon nitride, titanium nitride, zirconium oxide, aluminum oxide, aluminum nitride, and titanium oxide.

13. The method of claim 9, wherein the ceramic particles have an average particle size in the range of from about 0.2 pm to about 10 pm.

14. The method of claim 9, wherein the ceramic particles have an average particle size in the range of from about 1 pm to about 4 pm.

15. The method of claim 9, wherein the metal particles have an average particle size in the range of from about 5 pm to about 150 pm.

16. The method of claim 9, wherein the metal particles have an average particle size in the range of from about 15 pm to about 75 pm.

17. The method of claim 9, wherein the granules comprise from about 1 vol% to about 45 vol% of the dispersed phase.

18. A method for producing an article comprising:

densifying a preform;

wherein the preform comprises granules of a metal matrix composite;

19. The method of claim 18, wherein the granules comprise from about 1 vol% to about 45 vol% of the dispersed phase.

20. An article formed from granules of a metal matrix composite, the metal matrix composition comprising a ceramic dispersed phase in an aluminum or aluminum alloy matrix, and the granules having an average particle size of from about 100 pm to about 1 ,000 pm.