Fixed cutter drill bits including cutter elements with enhanced durability

Abstract

A cutter element for a fixed cutter drill bit includes a substrate having a central axis, a first end and a second end axially opposite the first end. In addition, the cutter element includes a polycrystalline diamond (PCD) cutting layer mounted to the first end of the substrate. The cutting layer includes a cutting face distal the substrate and a radially outer surface extending axially from the cutting face to substrate. The substrate comprises a laminate body having a first end axially proximal the cutting layer, a second end axially distal the cutting layer, and a radially outer surface extending axially from the first end of the laminate body to the second end of the laminate body. The laminate body includes a plurality of axially adjacent layers bonded together and arranged in a stack. The plurality of layers comprise a plurality of tungsten carbide (WC) layers including a first end WC layer disposed at the first end of the laminate body and a second end WC layer disposed at the second end of the laminate body. Each WC layer extends radially to the radially outer surface of the laminate body, and wherein each WC layer is made of a cemented WC material having a Young's Modulus. The plurality of layers also include a flexible layer axially positioned between a pair of axially adjacent WC layers of the plurality of WC layers. Each flexible layer is made of a metal or metal alloy material having a Young's Modulus that is less than the Young's Modulus of each WC layer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. provisional patent application Ser. No. 63 / 758,267 filed Feb. 13, 2025, and entitled “Fixed Cutter Drill Bits Including Cutter Elements with Enhanced Durability,” which is hereby incorporated herein by reference in its entirety for all purposes.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.FIELD

[0003] The present disclosure relates generally to earth-boring bits used to drill a borehole for the ultimate recovery of oil, gas or minerals. More particularly, the present disclosure relates to fixed cutter drill bits with cutter elements having improved durability.BACKGROUND

[0004] An earth-boring drill bit is typically mounted on the lower end of a drill string and is rotated by rotating the drill string at the surface or by actuation of downhole motors or turbines, or by both methods. With weight applied to the drill string, the rotating drill bit engages the earthen formation and proceeds to form a borehole along a predetermined path toward a target zone. The borehole thus created has a diameter generally equal to the diameter or “gage” of the drill bit.

[0005] Fixed cutter bits, also known as rotary drag bits, are one type of drill bit commonly used to drill boreholes. Fixed cutter bit designs include a plurality of blades angularly spaced about a bit face. The blades generally project radially outward along the bit face and form flow channels therebetween. Cutter elements are typically grouped and mounted on the blades. The configuration or layout of the cutter elements on the blades may vary widely, depending on a number of factors. One of these factors is the formation itself, as different cutter element layouts engage and cut the various strata with differing results and effectiveness.

[0006] The cutter elements disposed on the several blades of a fixed cutter bit are typically formed of extremely hard materials and include a layer of polycrystalline diamond (“PCD”) material. In the typical fixed cutter bit, each cutter element includes an elongate and generally cylindrical support member that is received and secured in a pocket formed in the surface of one of the several blades. In addition, each cutter element typically has a hard-cutting layer of polycrystalline diamond or other superabrasive material such as cubic boron nitride, thermally stable diamond, polycrystalline cubic boron nitride, or ultrahard tungsten carbide (meaning a tungsten carbide material having a wear-resistance that is greater than the wear-resistance of the material forming the substrate), as well as mixtures or combinations of these materials. The cutting layer is mounted to one end of the corresponding support member, which is typically formed of tungsten carbide.

[0007] While the bit is rotated, drilling fluid is pumped through the drill string and directed out of the face of the drill bit. The fixed cutter bit typically includes nozzles or fixed ports spaced about the bit face that serve to inject drilling fluid into the passageways between the several blades. The drilling fluid exiting the face of the bit through nozzles or ports performs several functions. In particular, the fluid removes formation cuttings (for example, rock chips) from the cutting structure of the drill bit. Otherwise, accumulation of formation cuttings on the cutting structure may reduce or prevent the penetration of the drill bit into the formation. In addition, the fluid removes formation cuttings from the bottom of the hole. Failure to remove formation materials from the bottom of the hole may result in subsequent passes by cutting structure to essentially re-cut the same materials, thereby reducing the effective cutting rate and potentially increasing wear on the cutting surfaces of the cutter elements. The drilling fluid flushes the cuttings removed from the bit face and from the bottom of the hole radially outward and then up the annulus between the drill string and the borehole sidewall to the surface. Still further, the drilling fluid removes heat, caused by contact with the formation, from the cutter elements to prolong cutter element life.BRIEF SUMMARY

[0008] Embodiments of cutter elements for fixed cutter drill bits are disclosed herein. In one embodiment, a cutter element for a fixed cutter drill bit configured to drill a borehole in a subterranean formation comprises a substrate having a central axis, a first end and a second end axially opposite the first end. In addition, the cutter element comprises a polycrystalline diamond (PCD) cutting layer mounted to the first end of the substrate. The cutting layer includes a cutting face distal the substrate and a radially outer surface extending axially from the cutting face to substrate. The substrate comprises a laminate body having a first end axially proximal the cutting layer, a second end axially distal the cutting layer, and a radially outer surface extending axially from the first end of the laminate body to the second end of the laminate body. The laminate body includes a plurality of axially adjacent layers bonded together and arranged in a stack. The plurality of layers comprise a plurality of tungsten carbide (WC) layers including a first end WC layer disposed at the first end of the laminate body and a second end WC layer disposed at the second end of the laminate body. Each WC layer extends radially to the radially outer surface of the laminate body. Each WC layer is made of a cemented WC material having a Young's Modulus. The plurality of layers comprise a flexible layer axially positioned between a pair of axially adjacent WC layers of the plurality of WC layers. Each flexible layer is made of a metal or metal alloy material having a Young's Modulus that is less than the Young's Modulus of each WC layer.

[0009] In another embodiment, a cutter element for a fixed cutter drill bit configured to drill a borehole in a subterranean formation comprises a substrate having a central axis, a first end, a second end axially opposite the first end. In addition, the cutter element comprises a polycrystalline diamond (PCD) cutting layer mounted to the first end of the substrate. The cutting layer includes a cutting face distal the substrate and a radially outer surface extending axially from the cutting face to substrate. The substrate comprises a laminate body extending from the first end of the substrate to the second end of the substrate. The laminate body is directly bonded to the cutting layer at the first end of the substrate. The laminate body comprises a plurality of tungsten carbide (WC) layers including a first end WC layer disposed at the first end of the laminate body and a second end WC layer disposed at the second end of the laminate body. Each WC layer extends radially to the radially outer surface of the substrate. Each WC layer is made of a cemented WC material having a Young's Modulus. The cemented WC material of each WC layer comprises a plurality of WC particles dispersed in a Cobalt (Co) binder. The cemented WC material of each WC layer comprises at least 6.0 wt % Co binder. The laminate body also comprises a plurality of flexible layers axially positioned between the first end WC layer and the second end WC layer. Each flexible layer is axially positioned between a pair of axially adjacent WC layers. Each flexible layer is made of a metal or metal alloy material having a Young's Modulus that is less than the Young's Modulus of each WC layer.

[0010] Embodiments described herein comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed embodiments in order that the detailed description that follows may be better understood. The various characteristics and features described above, as well as others, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the disclosed embodiments. It should also be realized that such equivalent constructions do not depart from the spirit and scope of the principles disclosed herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a detailed description of various exemplary embodiments, reference will now be made to the accompanying drawings in which:

[0012] FIG. 1 is a schematic view of a drilling system including an embodiment of a drill bit in accordance with the principles described herein;

[0013] FIG. 2 is a perspective view of the drill bit of FIG. 1;

[0014] FIG. 3 is an end view of the drill bit of FIG. 2;

[0015] FIG. 4 is a partial cross-sectional schematic view of the bit shown in FIG. 2 with the blades and the cutting faces of the cutter elements rotated into a single composite profile;

[0016] FIG. 5 is a perspective view of one of the cutter elements of drill bit of FIG. 2;

[0017] FIG. 6 is a side view of the cutter element of FIG. 5;

[0018] FIG. 7 is an exploded, cross-sectional side view of the cutter element of FIG. 5;

[0019] FIGS. 8A and 8B are photographs of conventional cutter elements illustrating wear flats formed during drilling operations in a controlled environment;

[0020] FIGS. 9A and 9B are photographs of cutter elements made in accordance with the principles described herein illustrating wear flats formed during drilling operations in a controlled environment;

[0021] FIG. 10 is a cross-sectional side view of an embodiment of a cutter element in accordance with the principles described herein;

[0022] FIG. 11 is a cross-sectional side view of an embodiment of a cutter element in accordance with the principles described herein;

[0023] FIG. 12 is a side view of an embodiment of a cutter element in accordance with the principles described herein;

[0024] FIG. 13 is a cross-sectional side view of the cutter element of FIG. 12;

[0025] FIG. 14 is an exploded, cross-sectional side view of the cutter element of FIG. 12;

[0026] FIG. 15 is a cross-sectional side view of an embodiment of a cutter element in accordance with the principles described herein;

[0027] FIG. 16 is a side view of an embodiment of a support member in accordance with the principles described herein bonded to a cutting layer;

[0028] FIG. 17 is a cross-sectional side view of an embodiment of a cutter element in accordance with the principles described herein;

[0029] FIG. 18 is a side view of an embodiment of a cutter element in accordance with the principles described herein;

[0030] FIG. 19 is a perspective schematic view of one set of layers of the laminate body of the substrate of FIG. 18 illustrating the keyed throughbore; and

[0031] FIG. 20 is a perspective view of the support member and cutting layer of FIG. 18.DETAILED DESCRIPTION

[0032] The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0033] Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing FIGS. are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0034] Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include only commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary.

[0035] In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct engagement between the two devices, or through an indirect connection that is established via other devices, components, nodes, and connections. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a particular axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to a particular axis. For instance, an axial distance refers to a distance measured along or parallel to the axis, and a radial distance means a distance measured perpendicular to the axis. Any reference to up or down in the description and the claims is made for purposes of clarity, with “up”, “upper”, “upwardly”, “uphole”, or “upstream” meaning toward the surface of the borehole and with “down”, “lower”, “downwardly”, “downhole”, or “downstream” meaning toward the terminal end of the borehole, regardless of the borehole orientation. As used herein, the terms “approximately,”“about,”“substantially,” and the like mean within 10% (i.e., plus or minus 10%) of the recited value. Thus, for example, a recited angle of “about 80 degrees” refers to an angle ranging from 72 degrees to 88 degrees.

[0036] Without regard to the type of bit, the cost of drilling a borehole for recovery of hydrocarbons may be very high, and is proportional to the length of time it takes to drill to the desired depth and location. The time required to drill the well, in turn, is greatly affected by the number of times the drill bit must be changed before reaching the targeted formation. This is the case because each time the bit is changed, the entire string of drill pipe, which may be miles long, must be retrieved from the borehole, section by section. Once the drill string has been retrieved and the new bit installed, the bit must be lowered to the bottom of the borehole on the drill string, which again must be constructed section by section. This process, known as a “trip” of the drill string, requires considerable time, effort and expense. Accordingly, it is desirable to employ drill bits which will drill faster and longer. The length of time that a drill bit may be employed before it must be changed depends upon a variety of factors. These factors include the bit's rate of penetration (“ROP”), as well as its durability or ability to maintain a high or acceptable ROP.

[0037] One factor that affects bit durability is the durability of each individual cutter elements of the bit as sufficient damage to one or more cutter elements can detrimentally affect cutting efficiency and ROP. The durability of an individual cutter element is often impacted by the presence of residual tensile stresses in the hard-cutting layer of polycrystalline diamond resulting from differences in coefficients of thermal expansion between the polycrystalline diamond hard-cutting layer and the underlying substrate, which is typically made of a different material such as tungsten carbide (WC), as the cutter element cools following formation via high temperature, high pressure sintering processes known in the art. Such tensile stresses in the hard-cutting layer, particular along or proximal the outer surfaces of the hard-cutting layer, coupled with downhole impact loads during drilling operations can lead to undesirable cracking and / or delamination of the hard-cutting layer. Accordingly, embodiments described herein are directed to cutter element assemblies and methods for forming cutter element assemblies that offer the potential to reduce internal stresses in the polycrystalline diamond cutting layers and provide an enhanced ability to absorb and dissipate impact loads during drilling operations.

[0038] Referring now to FIG. 1, a schematic view of an embodiment of a drilling system 10 in accordance with the principles described herein is shown. Drilling system 10 includes a derrick 11 having a floor 12 supporting a rotary table 14 and a drilling assembly 90 for drilling a borehole 26 from derrick 11. Rotary table 14 is rotated by a prime mover such as an electric motor (not shown) at a desired rotational speed and controlled by a motor controller (not shown). In other embodiments, the rotary table (for example, rotary table 14) may be augmented or replaced by a top drive suspended in the derrick (for example, derrick 11) and connected to the drillstring (for example, drillstring 20).

[0039] Drilling assembly 90 includes a drillstring 20 and a drill bit 100 coupled to the lower end of drillstring 20. Drillstring 20 is made of a plurality of pipe joints 22 connected end-to-end, and extends downward from the rotary table 14 through a pressure control device 15, such as a blowout preventer (BOP), into the borehole 26. The pressure control device 15 is commonly hydraulically powered and may contain sensors for detecting certain operating parameters and controlling the actuation of the pressure control device 15. Drill bit 100 is rotated with weight-on-bit (WOB) applied to drill the borehole 26 through the earthen formation. Drillstring 20 is coupled to a drawworks 30 via a kelly joint 21, swivel 28, and line 29 through a pulley. During drilling operations, drawworks 30 is operated to control the WOB, which impacts the rate-of-penetration of drill bit 100 through the formation. In this embodiment, drill bit 100 can be rotated from the surface by drillstring 20 via rotary table 14 or a top drive, rotated by downhole mud motor 55 disposed along drillstring 20 proximal bit 100, or combinations thereof (for example, rotated by both rotary table 14 via drillstring 20 and mud motor 55, rotated by a top drive and the mud motor 55, etc.). For example, rotation via downhole motor 55 may be employed to supplement the rotational power of rotary table 14, if required, or to effect changes in the drilling process. In either case, the rate-of-penetration (ROP) of the drill bit 100 into the borehole 26 for a given formation and a drilling assembly largely depends upon the WOB and the rotational speed of bit 100.

[0040] During drilling operations, a suitable drilling fluid 31 is pumped under pressure from a mud tank 32 through the drillstring 20 by a mud pump 34. Drilling fluid 31 passes from the mud pump 34 into the drillstring 20 via a desurger 36, fluid line 38, and the kelly joint 21. The drilling fluid 31 pumped down drillstring 20 flows through mud motor 55 and is discharged at the borehole bottom through nozzles in face of drill bit 100, circulates to the surface through an annular space 27 radially positioned between drillstring 20 and the sidewall of borehole 26, and then returns to mud tank 32 via a solids control system 36 and a return line 35. Solids control system 36 may include any suitable solids control equipment known in the art including, without limitation, shale shakers, centrifuges, and automated chemical additive systems. Control system 36 may include sensors and automated controls for monitoring and controlling, respectively, various operating parameters such as centrifuge rpm. It should be appreciated that much of the surface equipment for handling the drilling fluid is application specific and may vary on a case-by-case basis.

[0041] Referring now to FIGS. 2 and 3, drill bit 100 is a fixed cutter bit, sometimes referred to as a drag bit, and is designed for drilling through formations of rock to form a borehole. Bit 100 has a central or longitudinal axis 105, a first or uphole end 100a, and a second or downhole end 100b. Bit 100 rotates about axis 105 in the cutting direction represented by arrow 106. In addition, bit 100 includes a bit body 110 extending axially from downhole end 100b, a threaded connection or pin 120 extending axially from uphole end 100a, and a shank 130 extending axially between pin 120 and body 110. Pin 120 couples bit 100 to a drill string (not shown), which is employed to rotate the bit 100 in order to drill the borehole. Bit body 110, shank 130, and pin 120 are coaxially aligned with axis 105, and thus, each has a central axis coincident with axis 105.

[0042] The portion of bit body 110 that faces the formation at downhole end 100b includes a bit face 111 provided with a cutting structure 140. Cutting structure 140 includes a plurality of blades that extend from bit face 111. As best shown in FIG. 3, in this embodiment, cutting structure 140 includes three angularly spaced-apart primary blades 141 and three angularly spaced apart secondary blades 142. Further, in this embodiment, the plurality of blades (for example, primary blades 141, and secondary blades 142) are uniformly angularly spaced on bit face 111 about bit axis 105. In particular, the three primary blades 141 and the three secondary blades 142 (a total of six blades 141, 142) are uniformly angularly spaced about 60° apart. In other embodiments, one or more of the blades may be spaced non-uniformly about bit face 111. Still further, in this embodiment, each secondary blade 142 is disposed between a pair of circumferentially-adjacent primary blades 141, and each primary blade 141 is disposed between a pair of circumferentially-adjacent secondary blades 142. Although bit 100 is shown as having three primary blades 141 and three secondary blades 142, in general, bit 100 may comprise any suitable number of primary and secondary blades. As one example only, bit 100 may comprise two primary blades and four secondary blades, or three primary blades and two secondary blades.

[0043] Referring again to FIGS. 2 and 3, in this embodiment, primary blades 141 and secondary blades 142 are integrally formed as part of, and extend from, bit body 110 and bit face 111. Primary blades 141 and secondary blades 142 extend generally radially along bit face 111 and then axially along a portion of the periphery of bit 100. In particular, primary blades 141 extend radially from proximal central axis 105 toward the periphery of bit body 110. Primary blades 141 and secondary blades 142 are separated by drilling fluid flow courses 143. Each blade 141, 142 has a leading edge or side 141a, 142a, respectively, and a trailing edge or side 141b, 142b, respectively, relative to the cutting direction of rotation 106 of bit 100.

[0044] Each blade 141, 142 includes a cutter-supporting surface 144 that generally faces the formation during drilling and extends circumferentially from the leading side 141a to the trailing side 142 of the corresponding blade 141, 142. In this embodiment, a plurality of cutter elements 200 are fixably attached to each blade 141, 142 and extend from cutter-supporting surface 144 of each blade 141, 142. In particular, each cutter element 200 is received and seated in a mating recess or socket 145 extending circumferentially from the leading side 141a, 142b and cutter supporting surface 144 into the corresponding blade 141, 142. Cutter elements 200 are generally arranged adjacent one another in a radially extending row proximal the leading side 141a, 142a of each blade 141, 142, respectively. However, in other embodiments, the cutter elements (for example, cutter elements 200) may be arranged differently.

[0045] As will be described in more detail below, each cutter element 200 has a central axis 205, a first end 200a, and a second end 200b. First end 200a of each cutter element 200 leads the corresponding second end 200b relative to the cutting direction 106 of bit 100, and thus, each first end 200a may also be referred to herein as “leading” end 200a and each second end 200b may also be referred to herein as “trailing” end 200b. As shown in FIG. 3, each leading end 200a is proximal but positioned slightly forward of leading side 141a, 142a of the corresponding blade 141, 142, respectively, relative to cutting direction 106 of bit 100; and each trailing end 200b is distal and positioned rearward of leading side 141a, 142a of the corresponding blade 141, 142, respectively, relative to cutting direction 106 of bit 100.

[0046] Each cutter element 200 includes an elongated base portion or substrate 210 and a cylindrical disk or tablet-shaped, hard cutting layer 230 bonded to an end of substrate 210. As will be described in more detail below, unlike a conventional substrate made of solid tungsten carbide (WC), in this embodiment, each substrate 210 is defined by a laminate body 250 formed from a plurality of discs or layers of different materials. Each substrate 210 has a central axis 215, which defines the central axis 205 of the corresponding cutter element 200, and is generally positioned and secured in the corresponding pocket 145 formed in cutter supporting surface 144 of the corresponding blade 141, 142 to which it is fixably mounted. Each cylindrical disc, hard cutting layer 230 defines a cutting surface or cutting face 233 of the corresponding cutter element 200. In this embodiment, each cutting face 233 is completely planar and disposed in a plane oriented perpendicular to axes 205, 215, however, in other embodiments, one or more of the cutting faces (e.g., one or more cutting faces 233) may be non-planar and / or include one or more surfaces (e.g., one or more planar surfaces, one or more non-planar surfaces, or combinations thereof) oriented at an acute angle relative to the central axis of the corresponding cutter element (e.g., axes 205, 215 of the corresponding cutter element 200). As used herein, the phrase “non-planar” may be used to refer to a surface that includes one or more curved surfaces (for example, concave surface(s), convex surface(s), or combinations thereof), a plurality of distinct planar surfaces that intersect at distinct edges along the cutting face, or both. As best shown in FIG. 3, each cutter element 200 is mounted such that the corresponding central axis 205 is substantially parallel to or at an acute angle relative to the cutting direction 106 of bit 100. Such orientation results in the corresponding cutting face 233 being generally forward-facing relative to the cutting direction 106 of bit 100.

[0047] Referring still to FIGS. 2 and 3, bit body 110 further includes gage pads 147 of substantially equal axial length measured generally parallel to bit axis 105. Gage pads 147 are circumferentially-spaced about the radially outer surface of bit body 110. Specifically, one gage pad 147 intersects and extends from each blade 141, 142. In this embodiment, gage pads 147 are integrally formed as part of the bit body 110. In general, gage pads 147 can help maintain the size of the borehole by a rubbing action when cutter elements 200 wear slightly under gage. Gage pads 147 also help stabilize bit 100 against vibration.

[0048] Referring now to FIG. 4, an exemplary profile of blades 141, 142 (right side of FIG. 4) and an exemplary profile of cutting faces 233 (left side of FIG. 4) are shown as each would appear with blades 141, 142 and the cutting faces 233 of cutter elements 200 rotated into a single rotated profile. In rotated profile view, blades 141, 142 form a combined or composite blade profile 148a generally defined by cutter-supporting surfaces 144 of blades 141, 142, and the cutting tips of the cutting faces of cutter elements 200 form a combined or composite cutting face profile 148b generally defined by a line passing through the cutting tips. In this embodiment, the profiles of surfaces 144 of blades 141, 142 are generally coincident with each other, thereby forming a single composite blade profile 148a; and the cutting tips on different blades 141, 142 are generally disposed along the generally smooth and continuous cutting profile 148b. As shown in FIG. 4, profiles 148a, 148b have a similar shape and are generally parallel to each other when rotated into a single profile.

[0049] Composite blade profile 148a and bit face 111 may generally be divided into three regions conventionally labeled cone region 149a, shoulder region 149b, and gage region 149c. Cone region 149a is the radially innermost region of bit body 110 and composite blade profile 148a that extends from bit axis 105 to shoulder region 149b. In this embodiment, cone region 149a is generally concave. Adjacent cone region 149a is generally convex shoulder region 149b. The transition between cone region 149a and shoulder region 149b, referred herein to as the nose 149d, occurs at the axially outermost portion of composite blade profile 148a (relative to bit axis 105) where a tangent line to the blade profile 148a has a slope of zero. Moving radially outward, adjacent shoulder region 149b is the gage region 149c, which extends substantially parallel to bit axis 105 at the outer radial periphery of composite blade profile 148a. As shown in composite blade profile 148a, gage pads 147 generally define the gage region 149c and the outer radius R100 of drill bit 100. Outer radius R100 extends to and therefore defines the full gage diameter of bit 100.

[0050] Referring briefly to FIGS. 3 and 4, moving radially outward from bit axis 105, bit 100 and bit face 111 include cone region 149a, shoulder region 149b, and gage region 149c as previously described. Primary blades 141 extend radially along bit face 111 from within cone region 149a proximal bit axis 105 toward gage region 149c and outer radius R100. Secondary blades 142 extend radially along bit face 111 from cone region 149a proximal nose 149d toward gage region 149c and outer radius R100. Thus, in this embodiment, each primary blade 141 and each secondary blade 142 extends substantially to gage region 149c and outer radius R100. In this embodiment, secondary blades 142 extend radially inward just inside cone region 149a proximal nose 149d, and thus, secondary blades 142 occupy very little space on bit face 111 within cone region 149a. Although a specific embodiment of bit body 110 has been shown in described, one skilled in the art will appreciate that numerous variations in the size, orientation, and locations of the blades (for example, primary blades 141, secondary blades, 142, etc.) and cutter elements (for example, cutter elements 200) are possible.

[0051] Bit 100 includes an internal plenum extending axially from uphole end 100a through pin 120 and shank 130 into bit body 110. The plenum allows drilling fluid to flow from the drill string into bit 100. Body 110 is also provided with a plurality of flow passages extending from the plenum to downhole end 100b. As best shown in FIGS. 2 and 3, a nozzle 108 is seated in the lower end of each flow passage. Together, the plenum, passages, and nozzles 108 serve to distribute drilling fluid around cutting structure 140 to flush away formation cuttings and to remove heat from cutting structure 140, and more particularly cutter elements 200 during drilling.

[0052] Referring briefly to FIGS. 2-4, on each blade 141, 142, cutter elements 200 are arranged side-by-side in a row along the corresponding cutter-supporting surface 144 proximal leading side 141a, 142a. Thus, in this embodiment, cutter elements 200 are positioned radially adjacent one another (relative to bit axis 105) on a given blade 141, 142. However, in other embodiments, the cutter elements (for example, cutter elements 200) may be arranged in rows with one or more cutter element having different geometries on the same blade (for example, blade 141, 142).

[0053] Referring now to FIGS. 5-7, one cutter element 200 is shown and will be described it being understood each cutter element 200 of bit 100 is the same. As previously described, cutter element 200 includes elongated base portion or substrate 210 and cylindrical disk or tablet-shaped, hard cutting layer 230 bonded to an end of substrate 210. In this embodiment, substrate 210 is a cylindrical, laminate body 250 including an axial stack of a plurality of discs or layers comprising two or more different materials that offer the potential to reduce residual tensile stresses in hard cutting layer 230 as compared to conventional solid tungsten carbide (WC) substrate and enhance the durability of cutter element 200 as compared to conventional cutter element.

[0054] Cutting layer 230 and substrate 210 meet at a reference plane of intersection 219 that defines the location at which substrate 210 and cutting layer 230 are fixably attached. In this embodiment, plane of intersection 219 is oriented perpendicular to axes 205, 215.

[0055] Cutting layer 230 has a central axis 235 coincident with and coaxially aligned with central axes 205, 215, a first end 230a defining leading end 200a of cutter element assembly 200 and cutting face 233, a second end 230b opposite first end 230a, and a radially outer cylindrical surface 234 extending axially from first end 230a to second end 230b. Outer cylindrical surface 234 is disposed at an outer radius R234 measured radially from central axes 205, 215, 235. In this embodiment, second end 230b is defined by a planar surface oriented perpendicular to axes 205, 215, 235. In addition, in this embodiment, an annular bevel or chamfer 236 is provided at the intersection of cutting face 233 and outer cylindrical surface 234.

[0056] Cutting layer 230 is made of an ultrahard material such as polycrystalline diamond (PCD) or other superabrasive material. Part or all of the diamond in cutting layer 230 may be leached, finished, polished, or otherwise treated to enhance durability, efficiency or effectiveness. While cutting layer 230 is shown as a single layer of material mounted to substrate 210, in general, the cutting layer (for example, layer 230) may be formed of one or more layers of one or more materials. In addition, although substrate 210 is shown as a single, homogenous material, in general, the substrate (for example, substrate 210) may be formed of one or more layers or components made of one or more materials.

[0057] Substrate 210 has central axis 215 as previously described and which generally defines central axis 205 of cutter element 200. Thus, axes 205, 215, 235 are coincident and coaxially aligned. In addition, substrate 210 has a first end 210a bonded to second end 230b of cutting layer 230 at plane of intersection 219, a second end 210b opposite end 210a and distal cutting layer 230, and a radially outer surface 211 extending axially between ends 210a, 210b. In this embodiment, outer surface 211 is a cylindrical surface disposed at an outer radius R211 measured radially from central axis 215. Outer radius R211 is the same as outer radius R234, and thus, cylindrical outer surfaces 211, 234 are generally contiguous.

[0058] As best shown in FIG. 6, laminate body 250 defines substrate 210 and includes an axial stack of discs or layers. In particular, laminate body 250 includes an alternating arrangement or stack of a plurality of layers 251, 256. One layer 251 is axially disposed at and defines first end 210a of substrate 210, one layer 251 is axially disposed at and defines second end 210b of substrate 210, and one layer 256 is axially positioned between each pair of axially adjacent layers 251. Thus, layer 251 disposed at end 210a is bonded to cutting layer 230, and the layer 251 disposed at end 210b defines end 200b of cutter element 200. For purposes of clarity and further explanation, layer 251 axially adjacent cutting layer 230 may also referred to as “first end” layer 251 as it is disposed at first end 210a of substrate 210, layer 251 most distal cutting layer 230 may also be referred to herein as “second end” layer 251 as it is disposed at second end 210b of substrate 210, and each layer 251 axially positioned between first end layer 251 and second end layer 251 may also be referred to herein as an “intermediate” layer 251.

[0059] In this embodiment, body 250 includes four layers 251 and three layers 256, however, in other embodiments fewer or more layers 251, 256 may be provided with the understanding layers 251 define ends 210a, 210b and at least one layer 256 is axially positioned between each pair of axially adjacent layers 251. As will be described in more detail below, layers 251, 256 are fixably bonded and / or fused together to form the single-piece laminate body 250 using high temperature (~1400° C.), high pressure (HTHP) pressing conditions known in the art for forming cutter elements.

[0060] In this embodiment, each layer 251 is made of WC, and thus, may also be referred to as a WC layer 251. More specifically, each WC layer 251 is cemented WC comprising WC particles dispersed in a Cobalt (Co) binder. The WC particles preferably have a nominal grain size ranging from 0.50 micron to 5.00 micron, and alternatively about 2.0 micron; and the cemented WC is preferably at least 6.0 wt % Co binder.

[0061] In this embodiment, each layer 256 is made of a metal or metal alloy having a Young's modulus (E) less than a Young's modulus (E) of the WC material forming each layer 251. As a result, layers 256 are generally more flexible, less stiff, and easier to deform or stretch as compared to WC layers 251. Accordingly, each layer 256 may also be referred to herein as a “flexible” layer 256, and further, layers 256 generally function to reduce the overall stiffness of substrate 210, thereby offering the potential to improve the toughness and durability of substrate 210 and cutter element 200.

[0062] Although layers 256 are generally more flexible, less stiff, and easier to deform or stretch than WC layers 251, it should be appreciated that cutter element 200 is exposed to harsh downhole conditions during drilling operations, and thus, like the WC material forming each layer 251, the material composition of each layer 256 is preferably selected to be suitable for such environments. Examples of suitable metals and metal alloys that can be used to form one or more flexible layers 256 include: (1) metals such as Niobium (Nb), Tantalum (Ta), Rhenium (Re), Tungsten (W), Titanium (Ti), Molybdenum (Mo), Zirconium (Zr), Chromium (Cr), Hafnium (Hf), Vandium (Va), an alloy of one or more thereof, and combinations thereof, which exhibit relatively high melting points and generally do not melt during the HTHP process for forming cutter element 200; (2) metals such as Cobalt (Co), Nickel (Ni), Iron (Fe), Manganese (Mn), and alloys thereof, which exhibit lower melting points and melt during the HTHP formation of cutter element 200; (3) metals such as Copper (Cu), Silver (Ag), Gold (Au), Palladium (Pd), and alloys thereof, which exhibit a lower melting points and reduced tendency to form carbides with carbon; and (4) combinations of any two or more of the foregoing. The exemplary metals and metal alloys in group (1) above with relatively high melting points and that generally do not melt during the HTHP process for forming cutter element 200 but fuse and / or metallurgically bond with each axially adjacent WC layer 251 via melting, migration, and alloying of Co from the WC layer 251. The exemplary metals and metal alloys in group (2) above with lower melting points generally melt during the HTHP process for forming cutter element 200, generally remain in position, and fuse and / or bond with each axially adjacent WC layer 251 via melting, migration, and alloying of Co from the WC layer 251; melting migration, and alloying of the metal or metal alloys in group (2); and migration and intermingling of WC from each axially adjacent WC layer 251. The exemplary metals and metal alloys in group (3) above with lower melting points generally melt during the HTHP process for forming cutter element 200, are maintained in position, and fuse and / or bond with each axially adjacent WC layer 251 via migration and intermingling despite exhibiting a lower propensity to alloy with Co in the adjacent WC layers 251.

[0063] Referring still to FIG. 6, each layer 251, 256 has a first side 251a, 256a, respectively, a second side 251b, 256b, respectively, and a radially outer surface 252, 257, respectively, extending from first side 251a, 256a, respectively, to second side 251b, 257b, respectively. Each side 251a, 251b, 256a, 256b is generally planar and disposed in a plane oriented perpendicular to central axes 205, 215, 235. First side 251a of first end layer 251 (at end 210a) is bonded to cutting layer 230 at plane of intersection 219 and second side 251b of second end layer (at end 210b) defines end 200b of cutter element 200. However, each remaining side 251a, 251b, 256a, 256b is fixably bonded and / or fused to one axially opposed side 256b, 256a, 251b, 251a, respectively. In this embodiment, each layer 251, 256 is a cylindrical disc, and thus, each outer surface 252, 257 is a cylindrical surface. More specifically, each cylindrical outer surface 252, 257 is disposed at an outer radius measured radially from central axes 205, 215 that is equal to outer radii R211, R234. Thus, in this embodiment, each layer 251, 256 extends radially to and at least partially defines cylindrical outer surface 211 of substrate 210.

[0064] Each layer 251, 256 has a uniform thickness T251, T256, respectively, measured axially from first side 251a, 256a, respectively, to second side 251b, 256b, respectively. In this embodiment, the thickness T251 of each WC layer 251 ranges from 0.5 mm to 2.5 mm. More specifically, in this embodiment, the thickness T251 of first end layer 251 ranges from 0.5 mm to 2.0 mm, while the thickness T251 of each intermediate layer 251 and second end layer 251 ranges from 0.5 mm to 2.5 mm and is preferably 2.0 mm. In this embodiment, the thickness T256 of each layer 256 ranges from 0.1 mm to 1.5 mm. More specifically, in this embodiment, the thickness T256 of each layer 256 made of an exemplary metal or metal alloy from group (1) above preferably ranges from 0.1 mm to 0.5 mm; the thickness T256 of each layer 256 made of an exemplary metal or metal alloy from group (2) above preferably ranges from 0.3 mm to 1.5 mm; and the thickness T256 of each layer 256 made of an exemplary metal or metal alloy from group (3) above preferably ranges from 0.3 mm to 1.5 mm, and is more preferably 1.0 mm.

[0065] Although only one layer 256 is shown axially positioned between each WC layer 251 in FIG. 6, it should be appreciated that more than one layer 256 can be positioned between any pair of axially adjacent WC layers 251. Prior to forming laminate body 250 and substrate 210 via the HTHP process, each WC layer 251 can be provided as a solid, monolithic piece; each layer 256 can be provided as solid, monolithic disc, or alternatively in powder form, which solidifies during the HTHP process and bonds / fuses to the adjacent WC layer 251; and cutting layer 230 can be provided as a solid, monolithic piece that bonds / fuses to the adjacent WC layer 251 during he HTHP process, or alternatively as diamond powder that sinters during the HTHP process to form the solid cutting layer 230 while simultaneously bonds / fuses to the axially adjacent WC layer 251. In embodiments where a given layer 256 is provided as solid, monolithic disc, one or more through holes may extend axially through the layer 256 from first side 256a to second side 256b to enhance wicking and migration of Co from the WC layer 251 therethough. Further, in embodiments where a given layer 256 is provided as solid, monolithic disc, axially opposed sides 251b, 256a and / or axially opposed sides 251a, 256b may be textured (e.g., lines, grooves, pits, etc.) to enhance the corresponding surface areas and associated bonding interface therebetween.

[0066] It is believed that layers 251, 256 of different materials in laminate body 250 defining substrate 210 of cutter element 200 reduces tensile stresses in cutting layer 230, thereby offering the potential to enhance the toughness and durability of cutting layer 230 and cutter element 200. Without being limited by this or any particular theory, such benefit may arise for one or more reasons including, without limitation layers 251, 256 of different materials modify the stress state of cutting layer 230 by making substrate 210 less stiff, more compliant, and more ductile in the axial direction as compared to a conventional solid tungsten carbide substrate. For example, referring now to FIGS. 8A, 8B, 9A, 9B, conventional cutter elements “A1” and “A2” comprising a solid WC substrate (non-laminated) and PDC cutting layer, and similarly sized cutter elements “B1” and “B2” made in accordance with cutter elements 200 described above (a laminate body 250 including WC layers 251 and Nb layers 256, and a PDC cutting layer 230 bonded to the laminate body 250) were tested in controlled drilling environments under the same conditions (e.g., the same depth of cut, the same type of rock, the same coolant was used, etc.). The material composition of the cutting layer of each cutter element A1, A2, B1, B2 was the same; the HTHP process used to form each cutter element A1, A2, B1, B2 was the same; and the WC material of each WC layer 251 in cutter elements B1, B2 was the same as the WC material used to form the substrate of each conventional cutter element A1, A2. After testing, the wear flats on the cutting layers of the conventional cutter elements A1 and A2 shown in FIGS. 8A and 8B, respectively, were viewed and analyzed, and the wear flats on the cutting layers of the cutter elements B1 and B2 shown in FIGS. 9A and 9B, respectively, were viewed and analyzed. As shown in FIGS. 8A and 8B, the wear flats formed along the cutting layers of the conventional cutter elements A1 and A2 exhibited some chips, scoring, and spalling, which is generally associated with damage resulting from relatively high tensile stresses in the cutting layer of such conventional cutter elements. In contrast, as shown in FIGS. 9A and 9B, the wear flats along the cutting layers of cutter elements B1 and B2 were relatively smooth and substantially free of chips, scoring, and spalling, thereby suggesting a reduced or lower degree of tensile stresses in the corresponding cutting layers as compared to the cutting layers of the conventional cutter elements A1 and A2.

[0067] In the embodiment of cutter element 200 previously described and shown in FIGS. 5-7, each layer 251, 256 extends radially to and defines a portion of outer cylindrical surface 211 of substrate 210. In other words, cylindrical outer surface 252, 257 of each layer 251, 256, respectively, is disposed at an outer radius equal to outer radius R211 of substrate 210. However, in other embodiments, layers 256 axially positioned between WC layers 251 may not extend radially to outer cylindrical surface 211 of substrate 210 such that the entire radially outer surface 211 of substrate 210 is defined by the WC layers (e.g., WC layers 251). For example, referring now to FIG. 10, an embodiment of a cutter element 300 that can be used in place of any one or more cutter elements 200 of drill bit 100 previously described is shown. Cutter element 300 is substantially the same as cutter element 200 previously described with the exception that each flexible layer 256 is seated in a mating recess or pocket 254 in side 251b of a corresponding WC layer 251. In this embodiment, each recess 254 is cylindrical and coaxially aligned with layers 251, 256 and central axes 205, 215, 235. Each recess 254 extends radially from central axis 215 to an annular lip 255 disposed at the corresponding side 251b and contiguous with radially outer surface 252 of the corresponding WC layer 251. Thus, recesses 254 do not extend to outer surfaces 252 of corresponding WC layers 251. Consequently, flexible layers 256 do not extend radially to outer surface 211, and outer surface 211 is entirely defined by outer surfaces 252 of WC layers 251.

[0068] Cutter element 300 is generally formed in the same manner as cutter element 200 as previously described (i.e., via high temperature (~1400° C.), high pressure (HTHP) pressing conditions known in the art for forming cutter elements). In addition, laminated substrate 210 of cutter element 300 generally provides similar benefits and functionality as substrate 210 of cutter element 200 previously described.

[0069] In the embodiments of cutter elements 200, 300 previously described, WC layers 251, 351 and flexible layers 256, 356 are generally disc-shaped and have generally planar sides 251a, 251b, 351a, 351b, 256a, 256b, 356a, 356b. However, in other embodiments, the WC layers (e.g., WC layers 251, 351) and the flexible layers (e.g., flexible layers 256, 356) may have other geometries. For example, referring now to FIG. 11, an embodiment of a cutter element 400 in accordance with the principles described herein is shown. In general, cutter element 400 can be used in place of any one or more cutter elements 200 of drill bit 100 previously described is shown. Cutter element 400 is similar to cutter element 200 previously described, and thus, the differences between cutter elements 200, 400 will be described it being understood the other aspects of cutter elements 200, 400 are the same.

[0070] Cutter element 400 has a central axis 405, a leading end 400a, and a trailing end 400b. In addition, cutter element 400 includes an elongated base portion or substrate 410 and a hard cutting layer 230 as previously described bonded to substrate 410. Substrate 410 has a central axis 415, which defines the central axis 405 of cutter element 400. In addition, substrate 410 has a first end 410a bonded to second end 230b of cutting layer 230 at a plane of intersection 219, a second end 410b opposite end 410a and distal cutting layer 230, and a radially outer surface 411 extending axially between ends 410a, 410b. In this embodiment, outer surface 411 is a cylindrical surface disposed at an outer radius R411 measured radially from central axis 415. Outer radius R411 of substrate 410 is the same as outer radius R234 of cutting layer 230, and thus, cylindrical outer surfaces 411, 234 are generally contiguous.

[0071] Similar to substrate 210 previously described, substrate 410 is a cylindrical, laminate body 450. However, in this embodiment, substrate 410 includes a pair of WC layers 451 and a flexible layer 456 axially disposed between the pair of WC layers 451. One WC layer 451 is axially disposed at and defines first end 410a of substrate 410, one WC layer 451 is axially disposed at and defines second end 410b of substrate 410, and one flexible layer 456 is axially positioned between each pair of axially adjacent WC layers 451. Thus, in this embodiment, only two WC layers 451 are provided, only a single flexible layer 456 is axially positioned between the two WC layers 451, WC layer 451 disposed at end 410a is bonded to cutting layer 230, and the WC layer 451 disposed at end 410b defines end 400b of cutter element 400.

[0072] WC layers 451 have the same composition as WC layers 251 previously described, and flexible layer 356 has the same composition as flexible layers 256 previously described. In addition, each layer 451, 456 extends radially to cylindrical outer surface 411 of substrate 410. However, in this embodiment, layers 451, 456 are not cylindrical discs. More specifically, in this embodiment, each layer 451, 456 has a first side 451a, 456a, respectively, a second side 451b, 456b, respectively, and a radially outer cylindrical surface 452, 457, respectively, extending from first side 451a, 456a, respectively, to second side 451b, 456b, respectively. Side 451a of WC layer 451 defining end 410a of substrate 410 and bonded to cutting layer 230 at plane of intersection 219 may be planar or substantially planar, and side 451b of WC layer 451 defining end 410b of substrate 410 may be planar or substantially planar. However, axially opposed sides 451b, 456a of WC layer 451 at end 410a and flexible layer 456, respectively, are not completely planar; and axially opposed sides 451a, 456b of WC layer 451 at end 410b and flexible layer 456, respectively, are not completely planar. Rather, in this embodiment, axially opposed sides 451b, 456a of WC layer 451 at end 410a and flexible layer 456, respectively, have axially opposed mating radially outer annular planar surfaces 453a, 458a, respectively, and axially opposed mating radially inner convex and concave surfaces 453b, 458b, respectively; and axially opposed sides 451a, 456b of WC layer 451 at end 410b and flexible layer 456, respectively, have axially opposed mating radially outer annular planar surfaces 454a, 459a, respectively, and axially opposed mating radially inner concave and convex surfaces 454b, 459b, respectively.

[0073] Each layer 451, 456 has a thickness T451, T456, respectively, measured axially from first side 451a, 456a, respectively, to second side 451b, 456b, respectively. Due to the presence of non-planar surfaces along at least one side 451a, 451b, 456a, 456b of each layer 451, 456, each thickness T451, T456 is non-uniform, however, the minimum thickness T451, T456 of each layer 451, 456, respectively, is preferably the same as each thickness T251, T256, respectively, as previously described.

[0074] Cutter element 400, substrate 410, and cutting layer 230 are generally formed in the same manner as cutter element 200, substrate 210, and cutting layer 230 previously described (i.e., via high temperature (~1400° C.), high pressure (HTHP) pressing conditions known in the art for forming cutter elements). In addition, laminated substrate 410 generally provides similar benefits and functionality as substrate 210 previously described.

[0075] In the embodiments of cutter elements 200, 300, 400 previously described, laminated bodies 250, 350, 450 defining substrates 210, 310, 410, respectively, are formed (and cutting layers 230 are formed and / or bonded thereto) via HTHP pressing techniques generally known in the art. However, in other embodiments, the laminated bodies forming at least a portion of the substrate of the corresponding cutter element may be formed by other suitable techniques such as brazing.

[0076] Referring now to FIGS. 12 and 13, an embodiment of a cutter element 500 in accordance with the principles described herein is shown. In general, cutter element 500 can be used in place of any one or more cutter elements 200 of drill bit 100 previously described. Cutter element 500 has a central axis 505, a leading end 500a, and a trailing end 500b. In addition, cutter element 500 includes an elongated base portion or substrate 510 and a hard cutting layer 230 as previously described bonded to substrate 510. Substrate 510 has a central axis 515, which defines the central axis 505 of cutter element 500. Thus, axes 505, 515, 235 are coincident and coaxially aligned. In addition, substrate 510 has a first end 510a bonded to second end 230b of cutting layer 230 at a plane of intersection 219, a second end 510b opposite end 510a and distal cutting layer 230, and a radially outer surface 511 extending axially between ends 510a, 510b. In this embodiment, outer surface 511 is a cylindrical surface disposed at an outer radius R511 measured radially from central axis 515. Outer radius R511 of substrate 510 is the same as outer radius R234 of cutting layer 230, and thus, cylindrical outer surfaces 511, 234 are generally contiguous. Cutting layer 230 and substrate 510 meet at a reference plane of intersection 219 that defines the location at which substrate 510 and cutting layer 230 are fixably attached. In this embodiment, plane of intersection 219 is oriented perpendicular to axes 505, 515.

[0077] As best shown in FIG. 13, in this embodiment, substrate 510 includes a support member 520 bonded to cutting layer 230 and a laminate body 550 disposed about and fixably attached to support member 520. Support member 520 and laminate body 550 have central axes coincident with and coaxially aligned with central axis 515 of substrate 510. Support member 520 has a first end 520a defining end 510a of substrate 510, a second end 520b opposite end 520a and proximal end 510b of substrate 510, and a radially outer surface 521 extending axially from first end 520a to second end 520b. In this embodiment, support member 520 is made entirely of WC and has a T-shaped cross-sectional geometry in any plane containing central axis 515. In particular, support member includes a first cylindrical portion 522a extending axially from end 520a and a second cylindrical portion 522b extending axially from end 520b to first cylindrical portion 522a. Portions 522a, 522b are coaxially aligned with each other and axis 515. Portion 522a is axially adjacent to and bonded to cutting layer 230 at plane of intersection 219 at the interface of ends 230b, 510a, 520a, and laminate body 550 is disposed about portion 522b and bonded to portions 522a, 522b.

[0078] Cylindrical portions 522a, 522b have radially outer cylindrical surfaces 523a, 523b, respectively, disposed along outer surface 521 of support member 520. In this embodiment, outer cylindrical surface 523a is disposed at an outer radius measured radially from central axis 515 that is the same or substantially the same as outer radii R234, R511, whereas outer cylindrical surface 523b is disposed at an outer radius measured radially from central axis 515 that is less than the outer radius of first portion 522a and outer radii R234, R511. Accordingly, outer surface 521 includes an annular shoulder 524 extending radially inward from cylindrical surface 523a to cylindrical surface 523b. In this embodiment, annular shoulder 524 is an annular planar surface disposed in a plane oriented perpendicular to axis 515. In addition, in this embodiment, an annular fillet is provided at the intersection of annular shoulder 524 and cylindrical surface 523b to reduce and minimize stress concentrations at such location of support member 520.

[0079] Referring still to FIG. 13, laminate body 550 is mounted to cylindrical portion 522b of support member 520, positioned axially adjacent first portion 522a of support member 520, and fixably attached to both portions 522a, 522b of support member 520. In particular, body 550 has a central axis coincident with and coaxially aligned with axes 505, 515, 235, a first end 550a bonded to shoulder 524, a second end 550b distal first portion 522a and defining ends 500b, 510b, a radially outer surface 551 extending axially from first end 550a to second end 550b, and a radially inner surface 552 extending axially from first end 550a. In this embodiment, both ends 550a, 550b are defined by planar surfaces disposed in planes oriented perpendicular to central axes 505, 515.

[0080] Outer surface 551 and inner surface 552 of laminate body 550 are concentric, and coaxially aligned with central axes 505, 515. Outer surface 551 is a cylindrical surface defining a portion of outer surface 511 of substrate 510 and disposed at an outer radius measured radially from central axis 515 that is the same or substantially the same as outer radii R234, R511. In this embodiment, inner surface 552 is generally cylindrical and defines a recess or counterbore 553 extending axially from end 550a. First portion 522a of support member 520 is seated against first end 550a of laminate body 550 with second portion 522b of support member 520 seated in mating counterbore 553. As will be described in more detail below, laminate body 550 is bonded to both portions 522a, 522b of support member 520.

[0081] Referring still to FIGS. 13 and 14, laminate body 550 includes an arrangement or stack of a plurality of layers 561, 566, 568. In this embodiment, layers 561, 566, 568 are arranged in axially adjacent sets 560, with each set 560 including one or more of each layer 561, 566, 568. More specifically, each set 560 has a first end 560a, a second end 560b, and a cylindrical outer surface defining a portion of outer surface 511 of substrate 510. A layer 561 is disposed at and defines end 560b of each set 560, a layer 568 is disposed at and defines end 560a of each set 560, and a layer 566 is axially positioned between layers 561, 568. Select sets 560 of laminate body 550 are disposed about second portion 522b of support member 520 and include corresponding throughbores extending axially from first ends 560a to second ends 560b, which define portions of counterbore 553. It should be appreciated that each such throughbore extends axially through each layer 561, 566, 568 of the corresponding set 560.

[0082] In this embodiment, laminate body 550 includes six sets 560, with each set including three layers—one layer 561, one layer 566, and one layer 568. However, in other embodiments fewer or more sets 560 may be provided; each set 560 may include one or more of each layer 561, 566, 568; layers 561, 566, 568 in each set 560 may be arranged differently; or combinations thereof. Notwithstanding the foregoing and as will be described in more detail below, for each set 560, a layer 568 is provided at end 560a each set 560 and a layer 561 is provided at end 560b of each set 560.

[0083] Layers 561, 566, 568 within each set 560 are fixably bonded together and each pair of axially adjacent sets 560 are fixably bonded together to form a single-piece laminate body 550; and further, each set 560 is fixably bonded to second portion 522b of support member 520, set 560 disposed at first end 550a of substrate 550 (also referred to herein as “first end” set 560) is fixably bonded to shoulder 524 of support member 520, and set 560 disposed at second end 550b of substrate 550 (also referred to herein as “second end” set 560) defines second ends 500b, 510b and is fixably bonded to end 520b of support member 520 to form a single-piece substrate 510. As will be described in more detail below, in this embodiment, layers 561, 566, 568 and sets 560 are fixably bonded via brazing, and sets 560 are bonded to support member 520 via brazing. Thus, support member 520 and cutting layer 230 are formed and bonded together using techniques known in the art such as HTHP processing techniques used to form conventional cutter elements, and then laminate body 550 is formed via brazing and bonded to support member 520 via brazing to form cutter element 500. In general, laminate body 550 can be formed before or simultaneous with brazing to support member 520.

[0084] In this embodiment, each layer 561 is made of WC, and thus, may also be referred to as a WC layer 561. More specifically, each WC layer 561 is cemented WC comprising WC particles dispersed in a Cobalt (Co) binder. The WC particles preferably have a nominal grain size of about 2.0 micron grain size, and the cemented WC is preferably at least 6.0 wt % Co, alternatively ranges from 6.0 wt % to 20.0 wt %, and alternatively is about 13 wt %.

[0085] In this embodiment, each layer 566 is made of a metal or metal alloy having a Young's modulus (E) less than the WC material forming each layer 561. As a result, layers 566 are generally more flexible, less stiff, and easier to deform or stretch as compared to WC layers 561. Accordingly, each layer 566 may also be referred to herein as a “flexible” layer 566, and further, layers 566 generally function to reduce the overall stiffness of laminate body 550 and substrate 510, thereby offering the potential to improve the toughness and durability of substrate 510 and cutter element 500. Although layers 566 are generally more flexible, less stiff, and easier to deform or stretch than WC layers 561, it should be appreciated that cutter element 500 is exposed to harsh downhole conditions during drilling operations, and thus, like the WC material forming each layer 561, the material composition of each layer 566 is preferably selected to be suitable for such environments. In particular, the material composition of each layer 566 is preferably a metal or metal alloy having a Young's Modulus less than 560 GPa, and alternatively less than 540 GPa. Examples of suitable materials for each layer 566 include, without limitation, steel (e.g., tool steel), stainless steel, nickel (Ni), cobalt (Co), copper (Cu), silver (Ag), gold (Au), platinum (Pt), aluminum (Al), magnesium Mg), titanium (Ti), molybdenum (Mo), tungsten (W), niobium (Ni), tantalum (Ta), rhenium (Re), zirconium (Zr), hafnium (Hf), an alloy of one or more thereof (e.g., nickel-based superalloy, Inconel, cobalt-based superalloys, iron-based superalloys, etc.), and combinations thereof. In general, each layer 566 can be a disc made entirely of a solid metal or metal alloy (e.g., free of voids) or a disc made of a metal or metal alloy including one or more voids such as a metal mesh.

[0086] In this embodiment, each layer 568 is made of a metal or metal alloy brazing material such as silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), palladium (Pd), manganese (Mn), an alloy of one or more thereof, or combinations thereof. In some embodiments, the brazing material of each layer 568 has a melting temperature that is greater than the brazing material used to mount cutter element 500 to a bit body. Accordingly, each layer 568 may also be referred to herein as a “brazing” layer 568. Braze layers 568 are melted during manufacture of laminate body 550, substrate 510, and cutter element 500 (without melting any other components of cutter element 500) to braze and bond axially adjacent sets 560 together to form laminate body 550, and braze and bond laminate body 550 to support member 520 to form substrate 510 using brazing techniques known in the art. As previously described, a layer 568 is provided at end 560a each set 560 and a layer 561 is provided at end 560b of each set 560 such that axially adjacent sets 560 can be brazed together via brazing of layer 561 at each end 560b to end 560a of the axially adjacent set 560.

[0087] Referring still to FIGS. 13 and 14, each layer 561, 566, 568 is a generally cylindrical disc having a first side 561a, 566a, 568a, respectively, a second side 561b, 566b, 568b, respectively, and a radially outer surface 562, 567, 569, respectively, extending from first side 561a, 566a, 568a, respectively, to second side 561b, 567b, 568b, respectively. Each side 561a, 561b, 566a, 566b, 568a, 568b is generally planar and disposed in a plane oriented perpendicular to central axes 505, 515, 235. In this embodiment, each layer 561, 566, 568 is a cylindrical disc, and thus, each outer surface 562, 567, 569 is a cylindrical surface. More specifically, each cylindrical outer surface 562, 567, 569 is disposed at an outer radius measured radially from central axes 505, 515 that is equal to outer radii R511, R234. Thus, in this embodiment, each layer 561, 566, 568 extends radially to and at least partially defines cylindrical outer surface 511 of substrate 510.

[0088] As best shown in FIG. 14, each layer 561, 566, 568 has a uniform thickness T561, T566, T568, respectively, measured axially from first side 561a, 566a, 568a, respectively, to second side 561b, 566b, 568b, respectively. In this embodiment, the thickness T561 of each WC layer 561 ranges from 0.5 mm to 2.5 mm, the thickness T566 of each flexible layer 566 ranges from 0.3 mm to 1.5 mm, and the thickness T568 of each brazing layer 568 ranges from 0.1 mm to 1.5 mm.

[0089] To form laminate body 550, each WC layer 561 can be provided as a solid, monolithic piece; each flexible layer 566 can be provided as monolithic disc; and each brazing layer 568 can be provided as a solid, monolithic piece (e.g., foil) or powder that is melted and then allowed to cool to braze sets 560 together. Simultaneous with forming laminate body 550 or after forming laminate body 550, sets 560 can be brazed to support member 520 via melting brazing layer(s) 568 and then allowing them to cool to form cutter element 500.

[0090] It is believed that layers 561, 566 of different materials in laminate body 550 defining substrate 510 of cutter element 500 reduces tensile stresses in cutting layer 230, thereby offering the potential to enhance the toughness and durability of cutting layer 230 and cutter element 500. Without being limited by this or any particular theory, such benefit may arise for one or more reasons including, without limitation layers 561, 566 of different materials modify the stress state of cutting layer 230 by making substrate 510 less stiff, more compliant, and more ductile in the axial direction as compared to a conventional solid tungsten carbide substrate.

[0091] In the embodiment of cutter element 500 previously described and shown in FIGS. 12-14, each layer 561, 566, 568 extends radially to and defines a portion of outer cylindrical surface 511 of substrate 510. In other words, cylindrical outer surface 562, 567, 569 of each layer 561, 566, 568, respectively, is disposed at an outer radius equal to outer radius R511 of substrate 510. However, in other embodiments, flexible layers 566 may not extend radially to outer cylindrical surface 511 of substrate 510 such that the entire radially outer surface 511 of substrate 510 is defined by WC layers 561 with the sole exception of the very thin brazing layers 568 that may extend to outer surface 511 of substrate 510. For example, referring now to FIG. 15, an embodiment of a cutter element 600 that can be used in place of any one or more cutter elements 200 of drill bit 100 previously described is shown. Cutter element 600 is substantially the same as cutter element 500 previously described with the exception that each flexible layer 566 is seated in a mating recess or pocket 564 in side 561a of a corresponding WC layer 561. In this embodiment, each recess 564 is cylindrical and coaxially aligned with layers 561, 566, 568 and central axes 505, 515, 235. Each recess 564 extends radially from central axis 515 to an annular lip 565 disposed along side 561a and contiguous with radially outer surface 562 of the corresponding WC layer 561. Thus, recesses 564 do not extend to cylindrical outer surfaces 562 of corresponding WC layers 561. Consequently, flexible layers 566 do not extend radially to outer surface 511, and outer surface 511 is entirely defined by outer surfaces 562 of WC layers 561 with the exception of brazing layers 568 that may extend to outer surface 511 of substrate 510.

[0092] Cutter element 600 is generally formed in the same manner as cutter element 500 as previously described. In addition, substrate 510 of cutter element 600 generally provides similar benefits and functionality as substrate 510 of cutter element 500 previously described.

[0093] As previously described, support member 520 of substrate 510 of cutter element 500, 600 is made entirely of WC. However, in other embodiments, the support member (e.g., support member 520) may be made of other material(s). For example, referring now to FIG. 16, an embodiment of a support member 520′ that can be used in place of support member 520 previously described is shown. Support member 520′ is the same as support member 520 with the exception that second cylindrical portion 522b is made of two cylindrical sections 525a, 525b fixably attached end-to-end. In particular, first cylindrical section 523a is made of a WC material and extends axially from first cylindrical portion 522a (also made of WC); and second cylindrical section 523b is made of a metal or metal alloy having a Youngs Modulus less than the WC material of section 523a (e.g., steel or a super alloy) and extends axially from first cylindrical section 523a to end 520b. In this embodiment, cylindrical sections 523a, 523b are fixably attached end-to-end via brazing. Cylindrical section 523a, 523b are coaxially aligned with each other and the central axis of support member 520′, and have the same outer radius, which defines a uniform outer radius of second section 522b.

[0094] Cylindrical portion 522b made of a WC material (section 523a) and a metal or metal alloy with a Youngs Modulus less than the WC material (section 523b) reduces the stiffness of support member 520′ as compared to a support member made entirely of the WC material (e.g., support member 520). This provides some additional “give” along with a laminate body mounted thereto (e.g., laminate body 550). The softer material of section 523b may also provide cantilever bending “forgiveness” and ability to slightly flex if the corresponding cutter element experiences excessive angled loading at the cutting tip of the cutting layer. Still further, softer material of section 523b allows for the option of mechanical fastening (e.g. a threaded hole to receive a mating bolt as will be described in more detail below in connection with FIG. 17. Moreover, the softer material of section 523b can be either brazed to section 523a, or metallurgically fused (in situ) to section 523b in the press during a HTHP process and then machined down afterward to the smaller diameter

[0095] In the embodiment of cutter element 500 previously described and shown in FIGS. 12-14, sets 560 of layers 561, 566, 568 are axially stacked and brazed together, to form laminate body 550, and laminate body 550 is brazed to support member 520. To manufacture cutter element 500, layers 561, 566, 568 can be slidingly disposed on second portion 522b of support member 520 in the desired arrangement, the loose stack of layers 561, 566, 568 can then be axially urged against shoulder 524 while brazing layers 568 are melted and allowed to cool to form sets 560, braze sets 560 together to form laminate body 550, and braze sets 560 (and laminate body 550) to portions 522a, 522b of support member 520. In general, the loose stack of layers 561, 566,568 can be urged against shoulder 524 of support member 520 by any suitable means including gravity or compressed against shoulder 524 by other suitable means. For example, referring now to FIG. 17, an embodiment of a cutter element 700 that can be used in place of any one or more cutter elements 200 of drill bit 100 previously described is shown. Cutter element 700 is substantially the same as cutter element 500 previously described with the exception that support member 520 is replaced with support member 520′, a cylindrical end disc 710 is axially positioned against second end second end 550b of laminate body 550, and end disc 710 is bolted to support member 520′ to compress laminate body 550 between end disc 710 and shoulder 524 (before or after brazing sets 560 together and / or brazing sets 560 to support member 520′). End disc 710 has a central axis 715 coaxially aligned with central axes 505, 515, 235, a first planar side 710a, a second planar side 710b, a radially outer cylindrical surface 711 extending axially from side 710a to side 710b, a central counterbore 712 extending axially from side 710a, and a central bore 713 extending axially from counterbore 712 to side 710b. A bolt 720 having a head 721 and an externally threaded shaft 722 extending axially from head 721 extends through bore 713 and is threaded into a mating, internally threaded counterbore 526 extending axially from end 520b into second portion 522b of support member 520 until head 721 axially abuts an annular shoulder at the intersection of bore 713 and counterbore 712. End disc 710 axially abuts end 550b of laminate body 550, and thus, as bolt 720 is threaded into support member 520′, sets 560 and laminate body 550 are axially compressed between end disc 710 and shoulder 524. In general, sets 560 can be brazed together and / or sets 560 can be brazed to support member 520′ before or after being compressed between end disc 710 and shoulder 524.

[0096] In the embodiment of cutter element 500 previously described, outer surface 511 of substrate 510 is cylindrical and contiguous with outer cylindrical surface 234 of cutting layer 230, and outer radius R511 of substrate 510 and associated laminate body 550 is the same as outer radius R234 of cutting layer 230. However, in other embodiments, the substrate (e.g., substrate 520 and associated laminate body 550) may have other geometries. For example, referring now to FIG. 18, an embodiment of a cutter element 800 that can be used in place of any one or more cutter elements 200 of drill bit 100 previously described is shown. Cutter element 800 is substantially the same as cutter element 500 previously described with the exception that laminate body 550 of substrate 510 extends radially beyond outer surface 234 of cutting layer 230 and radially outer surface 551 of laminate body 550 has an oval or stadium prismatic shape extending axially from end 550a to end 550b as shown in FIG. 18; and support member 520 is replaced with support member 520′, and sets 560 are circumferentially oriented about support member 520′ and central axes 505, 515 and aligned via engagement of an elongate key 527 extending axially along outer surface of second portion 522b and mating slot 563 extending radially from the throughbore in each set 560 as shown in FIGS. 18 and 19.

[0097] Cutter element 800 is generally formed in the same manner as cutter element 500 as previously described. In addition, substrate 510 of cutter element 800 generally provides similar benefits and functionality as substrate 510 of cutter element 500 previously described.

[0098] While preferred embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the disclosure. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.

Claims

1. A cutter element for a fixed cutter drill bit configured to drill a borehole in a subterranean formation, the cutter element comprising:a substrate having a central axis, a first end and a second end axially opposite the first end;a polycrystalline diamond (PCD) cutting layer mounted to the first end of the substrate, wherein the cutting layer includes a cutting face distal the substrate and a radially outer surface extending axially from the cutting face to substrate;wherein the substrate comprises a laminate body having a first end axially proximal the cutting layer, a second end axially distal the cutting layer, and a radially outer surface extending axially from the first end of the laminate body to the second end of the laminate body, wherein the laminate body includes a plurality of axially adjacent layers bonded together and arranged in a stack, wherein the plurality of layers comprise:a plurality of tungsten carbide (WC) layers including a first end WC layer disposed at the first end of the laminate body and a second end WC layer disposed at the second end of the laminate body, wherein each WC layer extends radially to the radially outer surface of the laminate body, and wherein each WC layer is made of a cemented WC material having a Young's Modulus; anda flexible layer axially positioned between a pair of axially adjacent WC layers of the plurality of WC layers, wherein each flexible layer is made of a metal or metal alloy material having a Young's Modulus that is less than the Young's Modulus of each WC layer.

2. The cutter element of claim 1, wherein the laminate body includes a plurality of flexible layers, wherein one flexible layer is axially positioned between each pair of axially adjacent WC layers.

3. The cutter element of claim 1, wherein the cemented WC material of each WC layer comprises a plurality of WC particles dispersed in a Cobalt (Co) binder, wherein the cemented WC material comprises at least 6.0 wt % Co binder.

4. The cutter element of claim 3, wherein the plurality of WC particles of the cemented WC material have a nominal grain size of about 2.0 micron.

5. The cutter element of claim 1, wherein the metal or metal alloy of each flexible layer comprises Niobium (Nb), Tantalum (Ta), Rhenium (Re), Tungsten (W), Titanium (Ti), Molybdenum (Mo), Zirconium (Zr), Chromium (Cr), Hafnium (Hf), Vandium (Va), Boron (B), Cobalt (Co), Nickel (Ni), Iron (Fe), Manganese (Mn), Copper (Cu), Silver (Ag), Gold (Au), Palladium (Pd), an alloy of one or more thereof, or a combination thereof.

6. The cutter element of claim 1, wherein the flexible layer extends radially to the radially outer surface of the laminate body.

7. The cutter element of claim 2, wherein each layer of the laminate body has a first planar side, a second planar side, and a radially outer surface extending axially from the first planar side to the second planar side, wherein the first planar side of each flexible layer is bonded to the second planar side of an axially adjacent WC layer and the second planar side of each flexible layer is bonded to the first planar side of an axially adjacent WC layer.

8. The cutter element of claim 1, wherein each flexible layer is directly fused to each axially adjacent WC layer.

9. The cutter element of claim 1, wherein each layer of the laminate body has a first side, a second side, and a radially outer surface extending axially from the first side to the second side;wherein each WC layer has a thickness TWC measured axially from the first side of the WC layer to the second side of the WC layer, and each flexible layer has a thickness TF measured axially from the first side of the WC layer to the second side of the WC layer;wherein the thickness TWC of each WC layer ranges from 0.5 mm to 2.5 mm and the thickness TF of each flexible layer ranges from 0.1 mm to 1.5 mm.

10. The cutter element of clam 2, further comprising a plurality of braze layers, wherein each braze layer is made of a metal or metal alloy brazing material comprising Silver (Ag), Copper (Cu), Aluminum (Al), Nickel (Ni), an alloy of one or more thereof, or a combination thereof;wherein at least one braze layer is axially positioned between each pair of axially adjacent WC layers.

11. The cutter element of claim 10, wherein each flexible layer is a metal or metal alloy mesh.

12. The cutter element of claim 10, wherein the substrate comprises a support member having a first end defining the first end of the substrate, a second end distal the cutting layer, and a radially outer surface extending axially from the first end of the support member to the second end of the support member;wherein the support member includes a first cylindrical portion extending axially from the first end of the support member and a second cylindrical portion extending axially from the first cylindrical portion to the second end of the support member;wherein the first cylindrical portion defines a first cylindrical surface along the radially outer surface of the support member, the second cylindrical portion defines a second cylindrical surface along the radially outer surface of the support member, and an annular shoulder extends radially inward from the first cylindrical portion to the second cylindrical portion;wherein the laminate body is disposed about the second cylindrical portion of the support member and axially abuts the annular shoulder of the support member, wherein the laminate body is bonded to the support member.

13. The cutter element of claim 12, wherein the first end of the laminate body is brazed to the first cylindrical portion of the support member and the second cylindrical portion of the support member.

14. The cutter element of claim 13, wherein the laminate body includes a recess extending axially from the first end of the laminate body, wherein the second cylindrical portion of the support base is disposed in the recess of the laminate body.

15. The cutter element of claim 12, wherein the support member is made of a WC material.

16. The cutter element of claim 1, wherein the radially outer surface of the cutting layer is a cylindrical surface disposed at a radius R1 measured radially from the central axis of the substrate, wherein the radially outer surface of the laminate body is a cylindrical surface disposed at a radius R2 measured radially from the central axis of the substrate, and wherein the radius R2 is the same as the radius R1.

17. The cutter element of claim 1, wherein the laminate body extends radially beyond the radially outer surface of the cutting layer relative to the central axis of the substrate.

18. A cutter element for a fixed cutter drill bit configured to drill a borehole in a subterranean formation, the cutter element comprising:a substrate having a central axis, a first end, a second end axially opposite the first end;a polycrystalline diamond (PCD) cutting layer mounted to the first end of the substrate, wherein the cutting layer includes a cutting face distal the substrate and a radially outer surface extending axially from the cutting face to substrate;wherein the substrate comprises a laminate body extending from the first end of the substrate to the second end of the substrate, wherein the laminate body is directly bonded to the cutting layer at the first end of the substrate;wherein the laminate body comprises:a plurality of tungsten carbide (WC) layers including a first end WC layer disposed at the first end of the laminate body and a second end WC layer disposed at the second end of the laminate body, wherein each WC layer extends radially to the radially outer surface of the substrate, wherein each WC layer is made of a cemented WC material having a Young's Modulus, and wherein the cemented WC material of each WC layer comprises a plurality of WC particles dispersed in a Cobalt (Co) binder, wherein the cemented WC material of each WC layer comprises at least 6.0 wt % Co binder; anda plurality of flexible layers axially positioned between the first end WC layer and the second end WC layer, wherein each flexible layer is axially positioned between a pair of axially adjacent WC layers, wherein each flexible layer is made of a metal or metal alloy material having a Young's Modulus that is less than the Young's Modulus of each WC layer.

19. The cutter element of claim 18, wherein the plurality of WC particles of the cemented WC material have a nominal grain size of about 2.0 micron.

20. The cutter element of claim 18, wherein each flexible layer extends radially to the radially outer surface of the laminate body.

21. The cutter element of claim 18, wherein each layer of the laminate body has a first planar side, a second planar side, and a radially outer surface extending axially from the first planar side to the second planar side, wherein the first planar side of each layer of the laminate body is oriented perpendicular to the central axis and the second planar side of each layer of the laminate body is oriented perpendicular to the central axis;wherein each WC layer has a thickness TWC measured axially from the first side of the WC layer to the second side of the WC layer, and each flexible layer has a thickness TF measured axially from the first side of the WC layer to the second side of the WC layer;wherein the thickness TWC of each WC layer ranges from 0.5 mm to 2.5 mm and the thickness TF of each flexible layer ranges from 0.1 mm to 1.5 mm.

22. The cutter element of claim 21, wherein the metal or metal alloy of each flexible layer comprises Niobium (Nb), Tantalum (Ta), Rhenium (Re), Tungsten (W), Titanium (Ti), Molybdenum (Mo), Zirconium (Zr), Chromium (Cr), Hafnium (Hf), Vandium (Va), Boron (B), or an alloy thereof;wherein the thickness TF of each flexible layer ranges from 0.1 mm to 0.5 mm.

23. The cutter element of claim 21, wherein the metal or metal alloy of each flexible layer comprises Cobalt (Co), Nickel (Ni), Iron (Fe), Manganese (Mn), or an alloy thereof;wherein the thickness TF of each flexible layer ranges from 0.3 mm to 1.5 mm.

24. The cutter element of claim 21, wherein the metal or metal alloy of each flexible layer comprises Copper (Cu), Silver (Ag), Gold (Au), Palladium (Pd), or an alloy thereof;wherein the thickness TF of each flexible layer ranges from 0.3 mm to 1.5 mm.

Images