Patent Publication Number: US-11045870-B2

Title: Composite materials including nanoparticles, earth-boring tools and components including such composite materials, polycrystalline materials including nanoparticles, and related methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 13/253,758, filed Oct. 5, 2011, now U.S. Pat. No. 10,124,404, issued Nov. 13, 2018; which claims the benefit of U.S. Provisional Patent Application 61/391,344, filed Oct. 8, 2010, and entitled “COMPOSITE MATERIALS INCLUDING NANOPARTICLES, EARTH-BORING TOOLS AND COMPONENTS INCLUDING SUCH COMPOSITE MATERIALS, POLYCRYSTALLINE MATERIALS INCLUDING NANOPARTICLES, AND RELATED METHODS;” the disclosures of each of which are hereby incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present disclosure generally relate to earth-boring tools and to methods of manufacturing such earth-boring tools. More particularly, the present disclosure generally relates to composite materials and polycrystalline materials employing nanoparticles and which may be used for forming at least a portion of an earth-boring tool, and to methods of manufacturing such earth-boring tools. 
     BACKGROUND 
     Rotary drill bits are commonly used for drilling boreholes, or well bores, in earth formations. Rotary drill bits include two primary configurations. One configuration is the roller cone bit, which conventionally includes three roller cones mounted on support legs that extend from a bit body. Each roller cone is configured to spin or rotate on a support leg. Teeth are provided on the outer surfaces of each roller cone for cutting rock and other earth formations. The teeth often are coated with an abrasive, hard (“hardfacing”) material. Such materials often include tungsten carbide particles dispersed throughout a metal alloy matrix material. Alternatively, receptacles are provided on the outer surfaces of each roller cone into which hard metal inserts are secured to form the cutting elements. In some instances, these inserts comprise a superabrasive material formed on and bonded to a metallic substrate. The roller cone drill bit may be placed in a borehole such that the roller cones abut against the earth&#39;s formation to be drilled. As the drill bit is rotated under applied weight-on-bit, the roller cones roll across the surface of the formation, and the teeth crush the underlying formation. 
     A second, primary configuration of a rotary drill bit is the fixed-cutter bit (often referred to as a “drag” bit), which conventionally includes a plurality of cutting elements secured to a face region of a bit body. Generally, the cutting elements of a fixed-cutter type drill bit have either a disk shape or a substantially cylindrical shape. A hard, superabrasive material, such as mutually bonded particles of polycrystalline diamond, may be provided on a substantially circular end surface of each cutting element to provide a cutting surface. Such cutting elements are often referred to as “polycrystalline diamond compact” (PDC) cutters. The cutting elements may be fabricated separately from the bit body and are secured within pockets formed in the outer surface of the bit body. A bonding material such as an adhesive or a braze alloy may be used to secure the cutting elements to the bit body. The fixed-cutter drill bit may be placed in a borehole such that the cutting elements abut against the earth&#39;s formation to be drilled. As the drill bit is rotated, the cutting elements scrape across and shear away the surface of the underlying formation. 
     The bit body of a rotary drill bit of either primary configuration may be secured, as is conventional, to a hardened steel shank having an American Petroleum Institute (API) threaded pin for attaching the drill bit to a drill string. The drill string includes tubular pipe and equipment segments coupled end-to-end between the drill bit and other drilling equipment at the surface. Equipment such as a rotary table or top drive may be used for rotating the drill string and the drill bit within the borehole. Alternatively, the shank of the drill bit may be coupled directly to the drive shaft of a down-hole motor, which then may be used to rotate the drill bit. 
     The bit body of a rotary drill bit may be formed from steel. Alternatively, the bit body may be formed from a particle-matrix composite material. Such particle-matrix composite materials conventionally include hard tungsten carbide particles randomly dispersed throughout a copper or copper-based alloy matrix material (often referred to as a “binder” material). Such bit bodies conventionally are formed by embedding a steel blank in tungsten carbide particulate material within a mold, and infiltrating the particulate tungsten carbide material with molten copper or copper-based alloy material. Drill bits that have bit bodies formed from such particle-matrix composite materials may exhibit increased erosion and wear resistance, but lower strength and toughness, relative to drill bits having steel bit bodies. 
     As subterranean drilling conditions and requirements become ever more rigorous, there arises a need in the art for novel particle-matrix composite materials for use in bit bodies of rotary drill bits that exhibit enhanced physical properties and that may be used to improve the performance of earth-boring rotary drill bits. 
     SUMMARY 
     One embodiment of the disclosure comprises a composite material comprising a matrix material, hard particles dispersed within the matrix material, and nanoparticles dispersed within the matrix material between and comprising a different material than a material of the hard particles. 
     Another embodiment comprises a cutting element for use on an earth-boring drill bit, comprising a member including a segment-retaining portion and a drill bit attachment portion attachable to a drill bit, and a segment secured to the segment-retaining portion of the member and comprising a plurality of hard particles and a plurality of nanoparticles dispersed within a matrix material. 
     Yet another embodiment comprises an earth-boring tool for drilling subterranean formations, the earth-boring tool comprising a bit body including a crown region comprising a particle-matrix composite material, the particle-matrix composite material comprising hard particles and nanoparticles dispersed within a matrix material, wherein the nanoparticles comprise a different material from the hard particles, and at least one cutting structure disposed on the bit body. 
     A further embodiment comprises a polycrystalline compact cutting element for use in an earth-boring tool, the polycrystalline compact comprising a region of polycrystalline material comprising nanoparticles in interstitial spaces between inter-bonded crystals in the region of the polycrystalline material, wherein the nanoparticles comprise a catalyst material. 
     A still further embodiment comprises a method of forming a composite material, the method comprising melting a matrix material to form a molten matrix material, adding nanoparticles to the molten matrix material to form a molten matrix material mixture, infiltrating hard particles comprising a different material than the nanoparticles with the molten matrix material mixture, and cooling the molten matrix material mixture to form a composite material comprising the matrix material, the hard particles and nanoparticles in the matrix material interspersed between hard particles. 
     One other embodiment comprises a method of forming an earth-boring tool, the method comprising providing hard particles and nanoparticles within a cavity of a mold, wherein the nanoparticles comprise a different material from the hard particles, the cavity having a shape corresponding to at least a portion of a bit body of an earth-boring tool for drilling subterranean formations, infiltrating the hard particles and the nanoparticles with a molten matrix material, and cooling the molten matrix material to form a solid matrix material surrounding the hard particles and the nanoparticles. 
     Another embodiment comprises a method of forming a component of an earth-boring tool, the method comprising mixing hard particles, nanoparticles comprising a material different from a material of the hard particles, and particles comprising a metal matrix material to form a powder mixture, pressing the powder mixture to form a green body, and sintering the green body to a desired final density. 
     A further embodiment comprises a method of forming a polycrystalline compact cutting element for an earth-boring tool, the method comprising sintering a mass of hard particles interspersed with nanoparticles comprising a catalyst material under high-pressure, high-temperature conditions. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the present disclosure, advantages of the disclosure may be more readily ascertained from the description of some embodiments provided below, when read in conjunction with the accompanying drawings, in which: 
         FIG. 1  is an illustration representing one example of how a microstructure of a particle-matrix composite material of the present disclosure may appear under magnification; 
         FIG. 2  is a partial cross-sectional side view of an earth-boring rotary drill bit including the particle-matrix composite material of the present disclosure; and 
         FIG. 3  is an illustration representing one example of how a microstructure of a diamond table of the present disclosure may appear under magnification. 
         FIGS. 4 through 6  illustrate exemplary impregnated segments, and segment-retaining portions inherent in some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The illustrations presented herein are not meant to be actual views of any particular material, apparatus, or method, but are merely idealized representations which are employed to describe embodiments of the present disclosure. Additionally, elements common between figures may retain the same numerical designation. 
       FIG. 1  is an illustration providing one example of how the microstructure of a particle-matrix composite material  15  of the present disclosure may appear in under magnification acquired using, for example, an optical microscope, a scanning electron microscope (SEM), or other instrument capable of acquiring or generating a magnified image of the particle-matrix composite material  15 . As shown in  FIG. 1 , the particle-matrix composite material  15  may include a plurality of hard particles  50  dispersed within a matrix material  52 . The matrix material  52  comprises a plurality of nanoparticles  54  dispersed therein. In other words, the particle-matrix composite material  15  may include a plurality of discontinuous phase regions dispersed throughout a continuous metal or metal alloy phase, the metal or metal alloy phase including a plurality of nanoparticles  54 . In some embodiments, the hard particles  50  may comprise a material selected from diamond, boron carbide, boron nitride, silicon nitride, aluminum nitride, and carbides or borides of the group consisting of W, Ti, Mo, Nb, V, Hf, Zr, Si, Ta, and Cr. The matrix material  52  may be selected from the group consisting of copper-based alloys, iron-based alloys, nickel-based alloys, cobalt-based alloys, titanium-based alloys, aluminum-based alloys, iron- and nickel-based alloys, iron- and cobalt-based alloys, and nickel- and cobalt-based alloys. As used herein, the term “[metal]-based alloy” (where [metal] is any metal) means commercially pure [metal] in addition to metal alloys wherein the weight percentage of [metal] in the alloy is greater than or equal to the weight percentage of all other components of the alloy individually. In some embodiments, the matrix material  52  comprises cobalt. In some embodiments, each of the hard particles  50 , the matrix material  52 , and the nanoparticles  54  comprise a different material. 
     The nanoparticles  54  may have an average particle diameter of about five hundred nanometers (500 nm) or less. For example, in some embodiments, the nanoparticles  54  may have a diameter less than about one hundred nanometers (100 nm). By way of example and not limitation, the matrix material  52  may comprise between about one percent (1%) to about twenty-five percent (25%) by weight nanoparticles  54 . 
     As known in the art, the average particle size of the nanoparticles  54  within a microstructure may be determined by measuring grains of the microstructure under magnification. For example, a scanning electron microscope (SEM), a field emission scanning electron microscope (FESEM), or a transmission electron microscope (TEM) may be used to view or image a surface of a bit body  12  ( FIG. 2 ) (e.g., a polished and etched surface of the bit body  12 ) or a suitably prepared section of the surface in the case of the TEM as known in the art. Commercially available vision systems or image analysis software are often used with such microscopy tools, and these vision systems are capable of measuring the average particle size of nanoparticles within a microstructure. 
     The material of the nanoparticles  54  may be selected to improve a desired characteristic of the matrix material  52 . For example, the material of the nanoparticles  54  may be selected to improve at least one of the strength, yield point, ductility, impact strength, and abrasivity of the matrix material  52 . As a non-limiting example, in some embodiments, the nanoparticles  54  may comprise a harder material (e.g., as determined by a Vickers hardness test) than the matrix material  52 . By selecting the nanoparticles  54  to comprise a harder material than the matrix material  52 , at least one of the hardness, abrasion resistance, and strength of bit body  12  ( FIG. 2 ) may be improved. Similarly, the material of the nanoparticles  54  may be selected to have a higher strength, yield, ductility, impact strength, or abrasivity than the matrix material  52  to improve the those characteristics of the matrix material  52 . 
     The nanoparticles  54  may comprise, for example, at least one of borides, nitrides, oxides, carbides, and refractory metals. In some embodiments, the nanoparticles  54  may comprise, for example, at least one of diamond, polycrystalline cubic boron nitride, silicon nitride, silicon carbide, titanium carbide, tungsten carbide, tantalum carbide, or another hard material. The nanoparticles  54  may not be hard particles in some embodiments of the disclosure. For example, the nanoparticles  54  may comprise one or more of carbides, ceramics, oxides, intermetallics, clays, minerals, glasses, elemental constituents, various forms of carbon, such as carbon nanotubes, fullerenes, adamantanes, amorphous carbon, etc. Furthermore, in some embodiments, the nanoparticles  54  may comprise a carbon allotrope and may have an average aspect ratio of about one hundred to one (100:1) or less. In further embodiments, the nanoparticles  54  may comprise vanadium carbide or titanium diboride. 
     In further embodiments, the nanoparticles  54  may comprise vanadium carbide or titanium diboride. In some embodiments, the nanoparticles  54  may not be distinguishable from the matrix material  52  within the particle-matrix composite material, while in other embodiments, the nanoparticles  54  may maintain all or some of their original structure and integrity and be distinguishable within the matrix material  52 . For example, the nanoparticles  54  may partially or fully melt and/or dissolve within the matrix material  52  during formation of the particle-matrix composite material  15 . Such melting may result in alloying of the material of the nanoparticles  54  with the matrix material  52 . In some embodiments, the material of the nanoparticles  54  may become evenly dispersed throughout the matrix material  52 . In other embodiments, the matrix material  52  may be interspersed with areas of greater concentration of the material of the nanoparticles  54  where the nanoparticles  54  melted or dissolved. In some embodiments, the nanoparticles  54  may comprise a material that reacts with the matrix material  52 . The entire thickness of each nanoparticle of the plurality of nanoparticles  54  may react with the matrix material  52  or, alternatively, only an outer portion of each of the plurality of nanoparticles  54  may react with the matrix material  52  and an inner portion of each of the plurality of nanoparticles  54  may remain unreacted. In further embodiments, the plurality of nanoparticles  54  may help to create a spinodal decomposition of the matrix material  52 . 
     In some embodiments of the present disclosure, the nanoparticles  54  may be coated, metallized, functionalized, or derivatized to include functional groups. Derivatizing the nanoparticles  54  may increase the stability of the nanoparticles  54  in liquid-based processing steps, which may help to hinder or prevent agglomeration of the nanoparticles during formation of the particle-matrix composite material  15 . Such methods of forming derivatized nanoparticles are described in U.S. Provisional Patent Application No. 61/324,142, filed Apr. 14, 2010, and entitled “Method of Preparing Polycrystalline Diamond From Derivatized Nanodiamond,” the disclosure of which provisional patent application is incorporated herein in its entirety by this reference. 
     As previously discussed, the nanoparticles  54  may comprise a coating. In some embodiments, the coating may be inert or resistant to dissolving within the matrix material  52  to help maintain the integrity of the nanoparticle  54 . In some embodiments, the coating on the nanoparticles  54  may comprise a material configured to enhance the wettability of the nanoparticles  54  to the matrix material  52  and/or to prevent any detrimental chemical reaction from occurring between the nanoparticles  54  and the surrounding matrix material  52 . By way of example and not limitation, each nanoparticle of the nanoparticles  54  may comprise a coating of at least one of tin oxide (SnO 2 ), tungsten, nickel, and titanium. Furthermore, in some embodiments, trace amounts of at least one of silver, gold, and indium may, optionally, be included in the matrix material  52  to enhance the wettability of the matrix material relative to the nanoparticles  54 . 
     The particle-matrix composite material  15  including the nanoparticles  54  of the present disclosure may be used to form at least one component of an earth-boring tool. For example, an embodiment of an earth-boring rotary drill bit  10  of the present disclosure is shown in  FIG. 2 . The drill bit  10  includes a bit body  12  comprising the particle-matrix composite material  15  that includes the plurality of hard particles  50  dispersed throughout the matrix material  52  comprising the plurality of nanoparticles  54  ( FIG. 1 ) therein. By way of example and not limitation, the bit body  12  may include a crown region  14  and a metal blank  16 . The crown region  14  may be predominantly comprised of the particle-matrix composite material  15 , as shown in  FIG. 2 . The metal blank  16  may comprise a metal or metal alloy, and may be configured for securing the crown region  14  of the bit body  12  to a metal shank  20  that is configured for securing the drill bit  10  to a drill string (not shown). The metal blank  16  may be secured to the crown region  14  during fabrication of the crown region  14 , as discussed in further detail below. In additional embodiments, however, the drill bit  10  may not include a metal blank  16 . 
     Referring again to  FIG. 2 , the bit body  12  may be secured to the metal shank  20  by way of, for example, a threaded connection  22  and a weld  24  that extends around the drill bit  10  on an exterior surface thereof along an interface between the bit body  12  and the metal shank  20 . The metal shank  20  may be formed from steel, and may include a threaded pin  28  conforming to American Petroleum Institute (API) standards for attaching the drill bit  10  to a drill string (not shown). 
     As shown in  FIG. 2 , the bit body  12  may include wings or blades  30  that are separated from one another by junk slots  32 . Internal fluid passageways  42  may extend between the face  18  of the bit body  12  and a longitudinal bore  40 , which extends through the steel shank  20  and at least partially through the bit body  12 . In some embodiments, nozzle inserts (not shown) may be provided at the face  18  of the bit body  12  within the internal fluid passageways  42 . 
     The drill bit  10  may include a plurality of cutting structures on the face  18  thereof. By way of example and not limitation, a plurality of polycrystalline diamond compact (PDC) cutters  34  may be provided on each of the blades  30 , as shown in  FIG. 2 . Each of the PDC cutters  34  may comprise a diamond table  35  as described in greater detail below. The PDC cutters  34  may be provided along the blades  30  within cutting element pockets  36  formed in the face  18  of the bit body  12 , and may be supported from behind by buttresses  38 , which may be integrally formed with the crown region  14  of the bit body  12 . 
     The metal blank  16  shown in  FIG. 2  may be generally cylindrically tubular. In additional embodiments, the metal blank  16  may have a fairly complex configuration and may include external protrusions corresponding to blades  30  or other features extending on the face  18  of the bit body  12 . 
     The rotary drill bit  10  shown in  FIG. 2  may be fabricated by separately forming the bit body  12  and the shank  20 , and then attaching the shank  20  and the bit body  12  together. The bit body  12  may be formed by a variety of techniques, some of which are described in further detail below. 
     In some embodiments, the bit body  12  may be formed using so-called “suspension” or “dispersion” casting techniques. For example, a mold (not shown) may be provided that includes a mold cavity having a size and shape corresponding to the size and shape of the bit body  12 . The mold may be formed from, for example, graphite or any other high-temperature refractory material, such as a ceramic. The mold cavity of the mold may be machined using a five-axis machine tool. Fine features may be added to the cavity of the mold using hand-held tools. Additional clay work also may be required to obtain the desired configuration of some features of the bit body  12 . Where necessary, preform elements or displacements (which may comprise ceramic components, graphite components, or resin-coated sand compact components) may be positioned within the mold cavity and used to define the internal fluid passageways  42 , cutting element pockets  36 , junk slots  32 , and other external topographic features of the bit body  12 . 
     After forming the mold, a suspension may be prepared that includes a plurality of hard particles  50  and the nanoparticles  54  suspended within molten matrix material  52  ( FIG. 1 ). Matrix material  52  having a composition as described herein may be heated to a temperature sufficient to cause the mixture to melt, forming a molten matrix material  52  of desired composition. After forming the molten matrix material  52  of desired composition, hard particles  50  and nanoparticles  54  may be suspended and dispersed throughout the molten matrix material  52  to form the suspension. As previously mentioned, in some embodiments, the nanoparticles  54  may be coated with a material configured to enhance the wettability of the nanoparticles to the molten matrix material  52 , to prevent any detrimental chemical reaction from occurring between the nanoparticles  54  and the molten matrix material  52 , or both. 
     Optionally, a metal blank  16  ( FIG. 2 ) may be at least partially positioned within the mold such that the suspension may be cast around the metal blank  16  within the mold. 
     The suspension comprising the hard particles  50 , the nanoparticles  54 , and molten matrix material  52  may be poured into the mold cavity of the mold. As the molten matrix material  52  (e.g., the metal alloy materials) may be susceptible to oxidation, the infiltration process may be carried out under vacuum. In additional embodiments, the molten matrix material  52  may be substantially flooded with an inert gas or a reductant gas to prevent oxidation of the molten matrix material  52 . In some embodiments, pressure may be applied to the suspension during casting to facilitate the casting process and to substantially prevent formation of voids within the bit body  12 . 
     After casting the suspension within the mold, the molten matrix material  52  may be allowed to cool and solidify, forming the solid matrix material  52  of the particle-matrix composite material  15  including the nanoparticles  54  around the hard particles  50 . 
     In some embodiments, the bit body  12  may be formed using so-called “infiltration” casting techniques. For example, a mold (not shown) may be provided that includes a mold cavity having a size and shape corresponding to the size and shape of the bit body  12 . The mold may be formed from, for example, graphite or any other high-temperature refractory material, such as a ceramic. The mold cavity of the mold may be machined using a five-axis machine tool. Fine features may be added to the cavity of the mold using hand-held tools. Additional clay work also may be required to obtain the desired configuration of some features of the bit body  12 . Where necessary, preform elements or displacements (which may comprise ceramic components, graphite components, or resin-coated sand compact components) may be positioned within the mold cavity and used to define the internal fluid passageways  42 , cutting element pockets  36 , junk slots  32 , and other external topographic features of the bit body  12 . 
     After forming the mold, a plurality of hard particles  50  ( FIG. 1 ) may be provided within the mold cavity to form a body having a shape that corresponds to at least the crown region  14  of the bit body  12 . In some embodiments, the nanoparticles  54  may be provided within the mold cavity with the hard particles  50 . The nanoparticles  54  may be arranged within the mold such that the concentration of nanoparticles  54  is increased at areas of greater expected wear. Optionally, a metal blank  16  ( FIG. 2 ) may be at least partially embedded within the hard particles  50  such that at least one surface of the metal blank  16  is exposed to allow subsequent machining of the surface of the metal blank  16  (if necessary) and subsequent attachment to the shank  20 . 
     Molten matrix material  52  having a composition as previously described herein then may be prepared by heating the matrix material  52  to a temperature sufficient to cause the matrix material  52  to melt, thereby forming a molten matrix material  52 . In some embodiments, the nanoparticles  54  may be added to the molten matrix material  52 , in addition to or in lieu of nanoparticles  54  previously placed within the mold cavity. The molten matrix material  52  including, optionally, the nanoparticles  54  then may be allowed or caused to infiltrate the spaces between the hard particles  50  and optionally, the nanoparticles  54 , within the mold cavity. Optionally, pressure may be applied to the molten matrix material  52  to facilitate the infiltration process as necessary or desired. As the molten materials may be susceptible to oxidation, the infiltration process may be carried out under vacuum. In additional embodiments, the molten materials may be substantially flooded with an inert gas or a reductant gas to prevent oxidation of the molten materials. In some embodiments, pressure may be applied to the molten matrix material  52 , hard particles  50 , and nanoparticles  54  to facilitate the infiltration process and to substantially prevent the formation of voids within the bit body  12  being formed. 
     After the hard particles  50  and nanoparticles  54  have been infiltrated with the molten matrix material  52 , the molten matrix material  52  may be allowed to cool and solidify, forming a solid matrix material  52  of the particle-matrix composite material  15 . 
     In some embodiments, the bit body  12  may be formed using so-called particle compaction and sintering techniques such as, for example, those disclosed in application Ser. No. 11/271,153, filed Nov. 10, 2005, now U.S. Pat. No. 7,802,495, issued Sep. 28, 2010, and in application Ser. No. 11/272,439, filed Nov. 10, 2005, now U.S. Pat. No. 7,776,256, issued Aug. 17, 2010, each assigned to the Assignee of the present disclosure and the disclosure of which is incorporated herein in its entirety by reference. Briefly, a powder mixture may be pressed to form a green bit body or billet, which then may be sintered one or more times to form a bit body  12  having a desired final density. 
     The powder mixture may include a plurality of hard particles  50 , a plurality of nanoparticles  54 , and a plurality of particles comprising a matrix material  52 , as previously described herein. Optionally, the powder mixture may further include additives commonly used when pressing powder mixtures such as, for example, binders for providing lubrication during pressing and for providing structural strength to the pressed powder component, plasticizers for making the binder more pliable, and lubricants or compaction aids for reducing inter-particle friction. Furthermore, the powder mixture may be milled, which may result in the hard particles  50  being at least partially coated with the matrix material  52  and nanoparticles  54 . 
     The powder mixture may be pressed (e.g., axially within a mold or die, or substantially isostatically within a mold or container) to form a green bit body. The green bit body may be machined or otherwise shaped to form features such as blades, fluid courses, internal longitudinal bores, cutting element pockets, etc., prior to sintering. In some embodiments, the green bit body (with or without machining) may be partially sintered to form a brown bit body, and the brown bit body may be machined or otherwise shaped to form one or more such features prior to sintering the brown bit body to a desired final density. 
     The sintering processes may include conventional sintering in a vacuum furnace, the sintering in a vacuum furnace followed by a conventional hot isostatic pressing process, and sintering immediately followed by isostatic pressing at temperatures near the sintering temperature (often referred to as “sinter-HIP”). Furthermore, the sintering processes may include subliquidus phase sintering. In other words, the sintering processes may be conducted at temperatures proximate to but below the liquidus line of the phase diagram for the matrix material. For example, the sintering processes described herein may be conducted using a number of different methods known to one of ordinary skill in the art, such as the Rapid Omnidirectional Compaction (ROC) process, the CERACON® process, hot isostatic pressing (HIP), or adaptations of such processes. 
     When the bit body  12  is formed by particle compaction and sintering techniques, the bit body  12  may not include a metal blank  16  and may be secured to the shank  20  by, for example, one or more of brazing, welding, and mechanical interlocking. 
     The particle-matrix composite material  15  ( FIG. 1 ) of the present disclosure may also be used to form a hardfacing material (not shown) for use on an earth-boring tool. Hardfacing materials may be added on bit bodies and roller cones wherever increased wear resistance is desired. For example, in one embodiment, the particle-matrix composite material  15  may comprise a hardfacing material comprising a cemented carbide material. For example, the hard particles  50  may comprise tungsten carbide, and the matrix material  52  comprises cobalt having a plurality of nanoparticles  54  dispersed therein. 
     The particle-matrix composite material  15  ( FIG. 1 ) may also be used to form other earth-boring and other down-hole tools and components including, but not limited to, impregnated bits, hot pressed or sintered diamond-enhanced carbide segments, bearings, inserts for roller cone bits, substrates for superabrasive cutting elements such as polycrystalline diamond cutting elements, and any other components that may be formed from a particle-matrix composite material, as known in the art. For example, the particle-matrix composite material  15  may be included in rubbing blocks and bearing blocks as described in detail in U.S. Pat. No. 7,814,997, entitled Interchangeable Bearing Blocks for Drill Bits, and Drill Bits Including Same, which issued Oct. 19, 2010 and U.S. patent application Ser. No. 12/766,988, entitled Bearing Blocks for Drill Bits, Drill Bit Assemblies Including Bearing Blocks and Related Methods, filed Apr. 26, 2010, pending, the entire disclosure of each of which is incorporated herein by this reference. In addition, the particle-matrix composite material  15  may be included in impregnated bits and segments for such impregnated bits as described in detail in U.S. Pat. No. 6,241,036, entitled Reinforced Abrasive-Impregnated Cutting Elements, Drill Bits Including Same, which issued Jun. 5, 2001, and U.S. Pat. No. 6,742,611 entitled Laminated and Composite Impregnated Cutting Structures for Drill Bits, which issued Jun. 1, 2004, the entire disclosure of each of which is incorporated herein by this reference. 
     Referring to  FIGS. 4-6 , to enhance the strength with which an impregnated segment is bound to its corresponding securing member, the surface area of the interface  164 ,  164 ′,  164 ″ between an impregnated segment  160 ,  160 ′,  160 ″ and its corresponding support member  162 ,  162 ′,  162 ″, respectively, is preferably increased relative to that if a flat interface is employed. Accordingly, the segment-retaining portion of the support member  162 ,  162 ′,  162 ″ and the member-securing portion of the impregnated segment  160 ,  160 ′,  160 ″, respectively, may each comprise rough, preferably complementary, surfaces. Such high surface area interfaces prevent shearing or delamination of an impregnated segment off of a support member, which may be caused by bending stresses on the cutting element or to normal forces on the cutting element parallel to the member/segment interface. Accordingly, the mutually engaging surfaces of the impregnated segment-support member interface  164 ,  164 ′, and  164 ″ may include complementary thread cut (see  FIG. 4 ), waffle (see  FIG. 5 ), dove-tailed (see  FIG. 6 ), dotted, or cross-hatched surfaces; apertures or blind holes and complementary protrusions; heavily sandblasted or otherwise roughened surfaces; or other configurations that increase the mutually-engaging surface areas of the two components. High surface area impregnated segment support member interfaces are particularly useful in embodiments of the present invention that include relatively large, thin impregnated segments. 
     In further embodiments, the nanoparticles  54  may also be used to form a polycrystalline diamond table  35  such as in the polycrystalline diamond compact (PDC) cutters  34  of the drill bit  10  of  FIG. 2 .  FIG. 3  is an enlarged view illustrating how a microstructure of the diamond table  35  of the PDC cutters  34  may appear under magnification. As shown in  FIG. 3 , the diamond table  35  includes diamond crystals  56  that are bonded together by inter-granular diamond-to-diamond bonds. A catalyst material  58  used to catalyze the formation of the inter-granular diamond-to-diamond bonds is disposed in interstitial regions or spaces between the diamond crystals  56 . The catalyst material  58  includes a plurality of nanoparticles  54 , as previously described herein, and dispersed therethrough. The nanoparticles  54  may comprise, for example, less than about ten percent (10%) by volume of the catalyst material  58 . The catalyst material  58  may comprise any material that is capable of substantially catalyzing the formation of inter-granular bonds between grains of hard material during a high-temperature/high-pressure (HTHP) process, as known to those of ordinary skill in the art. For example, catalyst materials for diamond include cobalt, iron, nickel, other elements from Group VIIIA of the periodic table of the elements, and alloys thereof. The material of the nanoparticles  54  may be selected to improve a desired characteristic of the catalyst material  58 . In one embodiment, the nanoparticles may comprise diamond coated with a catalyst material. For example, the nanoparticles  54  may help to improve formation of the inter-granular bonds between the diamond crystals  56 , as the nanoparticles  54  may help strengthen the catalyst material  58 , or the nanoparticles  54  may help to prevent degradation of the inter-granular bonds during drilling operations. In addition, because of the increased surface area of the nanoparticles  54 , a lower concentration of the catalyst material  58  may be used to form the diamond table  35 . Additionally, the nanoparticles  54  may also make it easier to leach the catalyst material  58  out of the diamond table  35 , if desired. 
     By incorporating nanoparticles into the particle-matrix phase of composite materials, the composite materials may be tailored to exhibit a desired characteristic. For example, the composite material may exhibit an improved hardness, wear resistance, erosion resistance, fracture resistance, strength, yield point, ductility, impact strength, abrasivity, improved magnetic susceptibility, amongst other desirable improvements. While not wishing to be bound by any particular theory, it is believed that the presence of the nanoparticles may serve to tie up grain boundaries and dislocations in the composite material. 
     While the present disclosure is described herein in relation to embodiments of concentric earth-boring rotary drill bits that include fixed-cutters and to embodiments of methods for forming such drill bits and cutters, the present disclosure also encompasses other types of earth-boring tools such as, for example, core bits, eccentric bits, bicenter bits, reamers, mills, roller cone bits and hybrid bits employing both fixed and movable cutting structures, as well as methods for forming such tools. Thus, as employed herein, the term “bit body” includes and encompasses bodies of all of the foregoing structures, as well as components and subcomponents of such structures. 
     While the present disclosure has been described herein with respect to certain embodiments, those of ordinary skill in the art will recognize and appreciate that it is not so limited. Rather, many additions, deletions and modifications to the embodiments described and illustrated herein may be made without departing from the scope of the invention as hereinafter claimed, including legal equivalents. In addition, features from one embodiment may be combined with features of another embodiment while still being encompassed within the scope of the invention as contemplated by the inventors. Further, the invention has utility in drill bits and core bits having various different bit profiles, as well as various different cutter types.