MICROSTRUCTURE OF NBC-BASED CEMENTED CARBIDE

Abstract

Provided are niobium carbide-based cemented carbides and methods of manufacturing the same. The niobium carbide-based cemented carbides may be free of WC. Additionally, or alternatively, the niobium carbide-based cemented carbides may have a hard phase in which NbC in present in an amount greater than any other element of the hard phase. The niobium carbide-based cemented carbide may also have a binder phase devoid of Co.

Claims

1. A NbC-based cemented carbide, comprising: a binder phase comprising Ni; a hard phase comprising NbC in an amount greater than any other element of the hard phase; the hard phase comprising a core-rim structure, the core rim structure comprising NbC and mixed carbides of two or more of Nb, Mo and Ta.

2. The cemented carbide according to claim 1, further comprising W and the rim of the core-rim structure comprises mixed carbides of two or more of any of Nb, Mo, Ta and W.

3. The cemented carbide according to claim 2, wherein the core of the core-rim structure comprises (Nb,W)C.

4. The cemented carbide according to claim 1, wherein the amount of Nb in the cemented carbide is greater than 65 wt %.

5. The cemented carbide according to claim 2, wherein the amount of W in the cemented carbide is present in an amount of 1-15 wt.

6. The cemented carbide according to claim 1, wherein the binder phase comprises Ni in an amount greater than any other element of in the binder phase.

7. The cemented carbide according to claim 1, wherein the Ni is present in an amount of at least 3 wt %.

8. The cemented carbide according to claim 1, wherein the TaC is present in an amount of is at least 0.3 wt %.

9. The cemented carbide according to claim 1, in an amount of less than 1 wt %.

10. The cemented carbide according to claim 1, wherein the binder phase consists of Ni or Ni and Co; the hard phase consists of NbC or NbC and W; the core-rim structure comprises a core and a rim, the core consisting of NbC or NbC and (Nb,W)C and the rim consisting of mixed carbides of at least Nb, Mo and Ta, and optionally W.

11. The cemented carbide according to claim 1, wherein the binder phase comprises 3-15 wt % Ni and optionally Co; the NbC is present in the hard phase in an amount greater than 65 wt %; the core-rim structure comprises a core and a rim, the core comprising NbC and optionally (Nb,W)C, and the rim of said core-rim structure comprising carbides and/or mixed carbides or any of at least Nb, Mo, Ta and optionally W.

12. The cemented carbide according to claim 1, further including a crack having an intergranular path.

13. A method of making a cemented carbide article comprising a binder phase and a hard phase, the hard phase comprising a core-rim structure, the method comprising: preparing a batch of powdered materials comprising Ni, NbC, Mo.sub.2C and TaC; pressing the batch of powdered materials to form a pre-form; and sintering the pre-form to form the article.

14. The method according to claim 13, wherein the powdered batch of powdered materials further comprises WC in an amount 0-15 wt %.

15. The method according to claim 13, wherein the powdered batch comprises, in wt %, 65-85 NbC; 3-15 Ni; 2-10 Mo.sub.2C; 1-8 TaC; and 0-6 WC.

16. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0023] Specific implementations of the present subject matter will now be described with reference to the various examples and accompanying drawings in which:

[0024] FIG. 1 is a SEM image of a micrograph of sample A at 5000× magnifications using backscattered electron mode;

[0025] FIG. 2 is a SEM image of a micrograph of sample B at 5000× magnifications using backscattered electron mode;

[0026] FIG. 3 is a SEM image of a micrograph of sample C at 500× magnifications using backscattered electron mode;

[0027] FIG. 4 is a SEM image of a micrograph of sample D at 5000× magnifications using backscattered electron mode;

[0028] FIG. 5 is a SEM image of a micrograph of sample Eat 5000× magnifications using backscattered electron mode;

[0029] FIG. 6 is a SEM image of a micrograph of sample F at 5000× magnifications using backscattered electron mode;

[0030] FIG. 7 is a SEM image of a micrograph of sample I at 5000× magnifications using backscattered electron mode;

[0031] FIG. 8 is a SEM image of a micrograph of sample J at 5000× magnifications using backscattered electron mode;

[0032] FIG. 9 is a SEM image of a micrograph of sample Mat 5000× magnifications using backscattered electron mode;

[0033] FIG. 10 is a SEM image of a micrograph of sample N at 5000× magnifications using backscattered electron mode;

[0034] FIG. 11 is a SEM image of a micrograph of sample Q at 5000× magnifications using backscattered electron mode;

[0035] FIG. 12 is a SEM image of a micrograph showing a crack path in sample E at 5000× magnifications using backscattered electron mode compared with a SEM image of a micrograph showing a crack path in sample N at 5000× magnifications using backscattered electron mode.

DETAILED DESCRIPTION

[0036] The inventors have identified an NbC-based cemented carbide material having improved TRS and thermal conductivity for alike hardness-toughness levels as some WC-based cemented carbides.

[0037] The desired physical and mechanical characteristics are achieved, at least in part, by the selection of the metallic binder. Nickel presents good wettability towards the carbide ensuring a good cohesion of the material, which in turn facilitates sintering process and good mechanical properties. However, the relatively high solubility of NbC in nickel promotes certain NbC grain growth during sintering. In order to limit such grain growth, molybdenum may be added either as elemental and/or carbide form (i.e. Mo, MoC and/or Mo.sub.2C). Known NbC—Ni—Mo systems may present mechanical limitations such as low values for TRS and/or thermal conductivity. Surprisingly, however, the inventors have identified that the addition of tantalum, either in its elemental and/or its carbide form, contributes to the enhancement of such properties.

[0038] The inventors have identified that such desired physical and mechanical properties may be achieved via a NbC-based cemented carbide having a microstructure presenting a core-rim structure, for which transverse rupture strength is enhanced.

[0039] Optionally, the Ni content in the cemented carbide is at least 3% or at least 5%, by weight. The Ni may be present 3 to 25 wt %, 3 to 20 wt % or 3 to 15 wt % or in a range 5 to 25 wt %, 5 to 20 wt % or 5 to 15 wt %. Such a configuration provides a contribution to the good toughness values whilst maintaining hardness to an appropriate level, as well as high resistance to corrosion.

[0040] Optionally, the binder phase of the cemented carbide consists of Ni. In particular, the binder phase comprises exclusively or almost exclusively Ni. However, other components of the cemented carbide may be present as minor wt % components within the binder phase. Such minor components may be elemental or compound forms of remaining/other constituents of the cemented carbide such as Nb, Mo, Ta and optionally W and/or Co.

[0041] Optionally, the NbC content in the hard phase of the cemented carbide is at least 65 wt %, at least 70 wt %, at least 75 wt %, at least 80 wt %. Optionally, the NbC content in the cemented carbide is in a wt % range 65 to 85, 65 to 83 or 65 to 80. Such configurations provide a contribution to the desired hardness and high hot hardness values, galling and adhesion resistance.

[0042] Optionally, NbC may be the majority wt % component within the hard phase of the cemented carbide. Reference to the majority wt % component encompasses a mass/weight amount of NbC relative to a mass/weight of any other component present within the hard phase.

[0043] Optionally, NbC may be the majority wt % component within the cemented carbide based on mass/weight content as part of the cemented carbide relative to any other component present within the cemented carbide.

[0044] Optionally, the Mo.sub.2C content in the cemented carbide is at least 2 wt % or in a range 2 to 15, 2 to 12, 2 to 10 or 3 to 10. Such a configuration provides a contribution to the good corrosion resistance, maintains the desired mechanical properties including hardness and toughness and acts as a grain refiner. Below 2 wt %, no contribution as a grain refiner would be perceived and as a result, the heterogeneity of the different NbC grain sizes would constitute a defect in the microstructure which would in turn result in lower TRS values. Above the higher end, Mo.sub.2C would not only be present as a mixed carbide in the rim (or the interphase) of the core-rim structure and dissolved in the binder but would also start precipitating as a further phase. Such precipitation would constitute a defect in the microstructure which would in turn result in lower TRS values.

[0045] Optionally, the TaC content in the cemented carbide is at least 0.3 wt % or in a range 0.5 to 10, 1 to 9, 1 to 8, 2 to 7 or 2 to 6. Optionally, the TaC content in the cemented carbide is in a range 0.3 to 10, 0.5 to 9, 0.5 to 8, 1 to 7.5, 1 to 7, 1.5 to 7 or 1.5 to 6.5. Such a configuration provides a contribution to the enhanced TRS values as well as thermal conductivity whilst maintaining the desired mechanical properties including hardness and toughness. The addition of tantalum promotes the formation of a core-rim structure. Such core-rim structure constitutes an enhancement of the mechanical properties, in particular the TRS. The rim may act as an interphase between the core and the binder phase, making cracks undergo more deflections, with paths mostly going through the carbide grain/binder interphase, that minimizes crack propagation and in turn enhances the TRS.

[0046] Optionally, the cemented carbide is devoid of WC. In particular, the hard phase may comprise exclusively or consist of carbides of any combination of Nb, Mo and Ta. Optionally, WC may be included as a minority wt % component, the relative amount of which is less than a wt % of each of NbC, Ni and/or Mo.sub.2C. Optionally, WC may be included at less than 15 wt %, 10 wt %, 5 wt %, 2 wt %, 1 wt % or 0.5 wt %.

[0047] Optionally, the WC content in the cemented carbide may be at least 1 wt % but less than 15 wt % or in a range 1 to 15 wt %, 1 to 10 wt % or 1 to 5 wt %. Optionally, WC is included as a minority wt % component of the hard phase and/or the cemented carbide. Such configurations are determined due to inevitable impurities present in the production of the present NbC-based cemented carbide, using conventional techniques and equipment that is also used for WC-based cemented carbides. Such configurations also provide a contribution to the good hardness as well as the thermal conductivity. Additionally, such configurations may contribute, according to certain embodiments, to an increasing effect in the enhancement of TRS achieved by the addition of tantalum and/or tantalum carbide. Above 15 wt %, an additional WC phase may start precipitating. Such precipitates would negate the beneficial effect that the addition of TaC and the core-rim structure provides to the cemented carbide by decreasing the TRS values.

[0048] Optionally, the cemented carbide is devoid of Co. Preferably, the cemented carbide comprises exclusively Ni as the binder phase. Optionally, and in some embodiments, Co may be present at impurity level (i.e., less than 5 wt %, 3 wt %, 2 wt %, 1 wt %, 0.5 wt %, 0.05 wt % or 0.01 wt %).

[0049] Optionally, up to a 2 wt % of the Ni content may be substituted by Co for magnetic purposes only. For certain applications, such as can tooling, some equipment may include magnetic sensors for defect detection. Although one of the objectives of the present disclosure is to provide a cemented carbide free of cobalt, the inventors acknowledge the potential need, under certain circumstances, to provide a NbC-based cemented carbide capable of magnetic detection.

[0050] Optionally, up to a 2 wt % of the Ni content in the cemented carbide is substituted by Co. Optionally, the Co content in wt % relative to the total mass of the cemented carbide is in a wt % range 0 to 2.0, 0.1 to 2.0, 0.2 to 2.0 0.01 to 1.0 or 0.05 to 0.5.

[0051] Optionally, the cemented carbide comprises a binder phase and a hard phase, the binder phase comprising Ni and optionally Co; the hard phase comprising NbC, Mo.sub.2C, TaC and optionally WC; and wherein the cemented carbide comprises a balance of NbC; and wherein the hard phase comprises an NbC core and a shell surrounding the core that comprises Ta.

[0052] Optionally, the cemented carbide having a core and shell structure, is devoid of precipitation of any additional hard phases or interphases such as carbide or mixed carbide phases of Ta, Mo and W.

[0053] Optionally, the cemented carbide comprises a hard phase and a binder phase characterized in that: the binder phase comprises Ni; the hard phase comprises a core and shell structure; the core of said core and shell structure comprises NbC or optionally (Nb,W)C and the shell comprises mixed carbides of Mo, Ta, Nb and optionally W.

[0054] Optionally, the cemented carbide comprises a binder phase and a hard phase, the binder phase consisting of Ni and optionally Co; the hard phase consisting of or comprising NbC as the majority component and optionally W; the hard phase comprising a core-rim structure; the core of said core-rim structure consisting of NbC and/or optionally (Nb,W)C and the rim of said core-rim structure consisting of mixed carbides of at least Nb, Mo, Ta and optionally W.

[0055] Optionally, the cemented carbide comprises a binder phase and a hard phase, the binder phase comprising 3-15 wt % Ni and optionally Co; the hard phase comprising NbC as the majority component in an amount greater than 65 wt %; the hard phase comprising a core-rim structure; the core of said core-rim structure comprising NbC and/or optionally (Nb,W)C and the rim of said core-rim structure comprising carbides and/or mixed carbides or any of at least Nb, Mo, Ta and optionally W.

[0056] Optionally, the cemented carbide comprises a core and shell structure and comprises in wt %: 65-85 NbC; 3-15 Ni; 2-10 Mo.sub.2C; and 0.5-8 TaC; and optionally the cemented carbide comprises in wt %: 0 to 15 WC; and 0-2 Co. Preferably, the cemented carbide comprising a balance of NbC.

[0057] Optionally, the cemented carbide comprises a hard phase and a binder phase; the binder phase consisting of 3 to 15 wt % Ni and 0 to 2 wt % Co; the hard phase consisting of 65 to 85 wt % NbC, 2 to 10 wt % Mo.sub.2C, 1 to 7 wt % TaC and 0 to 15 wt % WC; the hard phase consisting of a core-rim structure; the core of said core-rim structure consisting of NbC or optionally (Nb,W)C; the rim of said core-rim structure consisting of mixed carbides of at least Nb, Mo, Ta and optionally W.

[0058] Optionally, the cemented carbide is devoid of nitrides and/or carbonitrides. Preferably, the cemented carbide comprises exclusively carbides and/or mixed carbides of Nb, Mo, Ta and optionally W. Optionally, the cemented carbide may comprise nitrides and/or carbonitrides present at impurity level. Optionally, the impurity level of such nitrides and/or carbonitrides is less than 0.05, 0.01 or 0.001 wt %.

[0059] Optionally, the wt % of NbC in the hard phase is greater than a wt % of any other component of the hard phase. Preferably, the majority wt % component of the hard phase is NbC.

[0060] Optionally, the cemented carbide is devoid of Ti and carbides, nitrides and/or carbonitrides of Ti. Optionally, the cemented carbide comprises 0 wt % Ti so as to be compositionally free of Ti.

[0061] Optionally, the cemented carbide is devoid of nitrogen or nitrogen compounds. However, the cemented carbide may comprise nitrogen or nitrogen compounds such as nitrides at impurity level such as less than 0.1 wt %, 0.05 wt % or 0.01 wt %.

[0062] Optionally, the cemented carbide presents a crack after fracture following an intergranular path preferentially, with minor transgranular fracture.

[0063] Reference to powdered materials within this specification is to the starting materials that form the initial powder batch for possible milling, optional formation of a pre-form compact and subsequent/final sintering. Referring to the starting material powder batch, optionally, the powdered materials comprise in wt % 65-85 NbC; 5-15 Ni; 2-10 Mo.sub.2C; 0.5-8 TaC. Optionally, the powdered materials comprise in wt % 65-85 NbC; 3-15 Ni; 2-10 Mo.sub.2C; 0.3-10 TaC. Optionally, the powdered materials comprise in wt % 65-85 NbC; 3-15 Ni; 2-10 Mo.sub.2C; 0.5-8 TaC. Optionally, the powdered materials comprise in wt % 65-85 NbC; 3-15 Ni; 2-10 Mo.sub.2C; 1-8 TaC Optionally, the powdered materials comprise in wt % 65-75 NbC; 3-15 Ni; 2-10 Mo.sub.2C; 1-7 TaC Optionally, the powdered materials comprise in wt % 65-75 NbC; 3-15 Ni; 2-10 Mo.sub.2C; 2-6 TaC. Optionally, the powdered materials further comprise WC in a range wt % 0-15; 0-10; 0-5; 1-10; 1-6 or 1-5. Optionally, the powdered materials may further comprise Co in a range wt % 0-2; 0.1-2 or 0.2 to 2.

[0064] Optionally, the step of sintering the pre-form to form the article comprises vacuum or HIP processing. Optionally, the sintering processing comprises processing at a temperature 1350-1500° C. n and a pressure 0-20 MPa.

[0065] Optionally, the step of sintering the pre-form to form the article does not involve adding nitrogen and/or is undertaken in the absence of nitrogen. In particular, sintering of the materials to form the cemented carbide is undertaken specifically with the exclusion of nitrogen that may otherwise be present as nitrides or within a nitrogen containing environment.

[0066] Optionally, a carbon content within the sintered cemented carbide is maintained within a predetermined range to further contribute to the good mechanical properties. Optionally, the carbon content of the sintered material may be held in a range between free carbon in the microstructure (upper limit) and eta-phase initiation (lower limit). Such limits will be appreciated by those skilled in the art.

Examples

[0067] Conventional powder metallurgical methods including milling, pressing, shaping and sintering were used to manufacture various sample grades of a cemented carbide according to the present disclosure. In particular, (fully sintered) cemented carbide grades with the wt % compositions according to Table 1 were produced according to known methods. Grades A to E are comparative samples and Grades F to Q are in accordance with the subject disclosure. All samples were prepared from powdered materials forming the hard phase and the binder phase.

[0068] Each of the sample mixtures Grades A to E and Grades F to Q were prepared from powdered materials forming the hard constituents and powders forming the binder. The following preparation method corresponds to Grade K of Table 1 below having starting powdered materials: WC 0.548 g, NbC 42.667 g, TaC 2.189 g, Mo.sub.2C 3.290 g, Ni 7.130 g, PEG 1.400 g, ethanol 50 ml. It will be appreciated by those skilled in the art that it is the relative amounts of the powdered materials that allow the skilled person to achieve the fully sintered material and suitable adjustment is needed to make the powdered batch and achieve the final fully sintered composition of the cemented carbides of Table 1. The powders were wet milled together with lubricant and anti-flocculating agent until a homogeneous mixture was obtained and granulated by drying. The dried powder was pressed to form a green part according to the abovementioned standard shapes and sintered using SinterHlP at 1350-1500° C.

[0069] Table 1 details the composition (wt %) of the various comparative samples A to E and samples F to Q encompassed by the present cemented carbide.

TABLE-US-00001 TABLE 1 Example Grade Compositions F to Q and Comparative Grades A to E NbC Ni Mo.sub.2C WC TaC Sample (wt %) (wt %) (wt %) (wt %) (wt %) A (comparative) 81 13 4 2 0 B (comparative) 81 8 9 2 0 C (comparative) 58 13 9 16 4 D (comparative) 45 13 9 29 4 E (comparative) 78 13 9 0 0 F 80.5 8 9 2 0.5 G 75 13 9 2 1 H 75 13 9 1 2 I 75 13 9 0 3 J 78 8 9 2 3 K 76 13 6 1 4 L 70 13 9 4 4 M 68 13 9 4 6 N 70 13 9 0 8 O 72 13 3 4 8 P 73 13 6 4 4 Q 64 13 15 4 4

[0070] Characterization

[0071] Hardness tests were carried out according to ISO 3878:1983; toughness tests according to Palmqvist, ISO 28079:2009; and transverse rupture strength (TRS) test were carried out according to ISO 3327:2009, the test pieces being of Type A, rectangular cross-section. Vickers indentation test was performed using 30 kgf (HV30) to assess hardness. Palmqvist fracture toughness was calculated according to:

[00001]$K1c=A\sqrt{HV}\sqrt{\frac{P}{.Math.L}}$

[0072] Where A is a constant of 0.0028, HV is the Vickers hardness (N/mm2), P is the applied load (N) and Σ L is the sum of crack lengths (mm) of the imprint.

[0073] The test pieces for transverse rupture strength's determination were beams of Type A (rectangular cross-section with 4×5×45 mm.sup.3 dimension). The samples were places between two supports and loaded in their center until fracture occurred (3-points bending). The maximum load was recorded and averaged over minimum five samples per test. The results are shown in Table 2:

TABLE-US-00002 TABLE 2 Transverse Rupture Strength Values for Samples A to Q Precipitation TRS Core-rim of secondary Sample (MPa) structure hard phases A (comparative) 1264 No No B (comparative) 1121 No No C (comparative) 1294 Yes Yes D (comparative) 931 Yes Yes E (comparative) 1320 No No F 1230 Yes No G 1400 Yes No H 1420 Yes No I 1460 Yes No J 1540 Yes No K 1356 Yes No L 1530 Yes No M 1604 Yes No N 1554 Yes No O 1500 Yes No P 1600 Yes No Q 1290 Yes No

[0074] Characterization of Samples A to Q was undertaken including also microstructural analysis using scanning electron microscopy (SEM). Sintered samples were mounted in bakelite resin and polished down to 1 μm prior to further characterization.

[0075] Crack propagation testing was also conducted. Samples E and N were prepared according to ISO Standard 3327:2009. The face of the rectangular TRS-A samples E and N, to be submitted to tension, were grinded and polished up to a mirror-like surface following standard metallographic preparation according to ASTM standard B665-03: Standard Guide for Metallographic Sample Preparation of Cemented Tungsten Carbide. Three Vickers indentation with tests 30 kg of load were done at the center of each sample, in the polished face, with 1 mm distance between them. This was conducted with an Emco DuraScan Hardness tester machine. Samples were then deposited as for 3-point bending testing in a Shimadzu universal testing machine. The face containing the indentation imprints faced downwards so as to be in tension during the test. Monotonic load was then applied up to rupture of the samples. One of the three indentation imprints promoted rupture, while the other two presented cracks at the corner and grown in direction transversal to the applied load. After testing, the crack path at the crack tip was observed by SEM to qualify the deflection. Observation made far from the nucleation point (i.e. at the indentation imprint) assures that propagation of the crack was done at monotonic load and far from the plastic deformation field of the imprint.

[0076] Referring to Table 1 and 2, the present cemented carbide samples combine NbC—Ni— Mo.sub.2C system and optimum additions of TaC and optionally WC to form a core-rim (core and shell) structure which results in an enhancement of TRS values. FIG. 5 shows the microstructure of comparative sample E, which consists of a plain NbC—Ni— Mo.sub.2C system. When comparing such microstructure with those of the inventive samples I (addition of 3 wt % TaC) and N (addition of 8 wt % TaC), FIGS. 7 and 10 respectively, the appearance of a core-rim structure can be appreciated. While FIG. 5 presents a typical cemented carbide microstructure with NbC carbide grains (hard phase) surrounded by the binder phase of Ni and the dissolved molybdenum, FIGS. 7 and 10 present a core-rim microstructure where the hard phase is composed by the core and the rim surrounded by the binder phase. The TRS value of comparative sample E is about 1320 MPa, sample I about 1460 MPa and sample N about 1554 MPa. Therefore, it can be seen how the addition of TaC in the composition leads to the formation of a core-rim structure which in turn enhances the TRS values. It is also confirmed that presence of WC is not necessary for such improvement.

[0077] Using comparative sample B comparison with sample J which correspond to FIGS. 1 and 8 respectively it can be noted that comparative sample B, which contains an addition of 2 wt % WC, presents a typical cemented carbide microstructure. However, sample J, with the addition of a 3 wt % TaC to the composition the core-rim structure appears and the TRS is increased from about 1121 MPa to about 1540 MPa.

[0078] The upper limits of the optional addition of WC can be noted by comparing comparative samples C (FIG. 3) and D (FIG. 4) with the inventive sample M (FIG. 9). While FIGS. 3 and 4 do present a core-rim structure, the wt % amount of WC present is such that it also starts precipitation as a separate secondary hard phase. FIG. 3, with a composition including 16 wt % WC, shows localized precipitation of (W, Mo)C and FIG. 4, with a composition including 29 wt % WC, shows separate precipitates of WC secondary hard phase in all its microstructure. In contrast, lower amounts of WC addition, such as the one shown in FIG. 9 which includes 4 wt % WC, no separate secondary precipitates can be observed. These precipitates are shown to be detrimental for TRS values as can be seen from Table 2, where the inventive sample shows a value of about 1604 MPa in comparison to comparative samples C and D with TRS values of about 1294 and 931 MPa, respectively.

[0079] Referring to FIG. 12, a comparison between microstructures of comparative sample E and inventive sample N is shown. Both microstructures show a crack and its path across the microstructure. It is evidenced that the crack path for comparative sample E, which represents a simple NbC—Ni— Mo.sub.2C system, is preferentially transganular (i.e. through the grains). However, for inventive sample E which contains an addition of 8 wt % TaC and presents a core-rim structure, the crack follows an intergranular path preferentially, with minor transgranular fracture. The inventors appreciate the deflection of the crack in sample E is promoted by the microstructure of the composite, influencing the resistance to crack propagation of the material.

[0080] Unless defined otherwise all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently described subject matter pertains.

[0081] Unless otherwise indicated, any reference to “wt %” refers to the mass fraction of the component relative to the total mass of the cemented carbide.

[0082] Where a range of values is provided, for example, concentration ranges, percentage range or ratio ranges, it is understood that each intervening value, to the tenth of the unit of the lower limit, unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the described subject matter. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and such embodiments are also encompassed within the described subject matter, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the described subject matter.

[0083] It should be understood that the terms “a” and “an” as used above and elsewhere herein refer to “one or more” of the enumerated components. It will be clear to one of ordinary skill in the art that the use of the singular includes the plural unless specifically stated otherwise. Therefore, the terms “a”, “an” and “at least one” are used interchangeably in this application.

[0084] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as size, weight, reaction conditions and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present subject matter. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0085] Throughout the application, descriptions of various embodiments use “comprising” language; however, it will be understood by one of skill in the art that, in some instances, an embodiment can alternatively be described using the language “consisting essentially of” or “consisting of”.

[0086] The present subject matter being thus described, it will be apparent that the same may be modified or varied in many ways. Such modifications and variations are not to be regarded as a departure from the spirit and scope of the present subject matter, and all such modifications and variations are intended to be included within the scope of the following claims.