WC Phase Research Articles

Investigation of the Influence of the Oxygen Flow Rate on the Mechanical, Structural and Operational Properties of 86WC-10Co-4Cr Coatings, as Determined Using the High-Velocity Oxyfuel Spraying Method

The structural-phase composition and tribological and performance properties of coatings based on an 86WC-10Co-4Cr composition obtained by the HVOF method at varying (150 L/min, 170 L/min, 190 L/min) oxygen flow rates were studied. The results showed that the coefficient of friction of coatings in gear oil remained almost unchanged with the variation in oxygen flow rate. However, microhardness increased significantly with an increasing oxygen flow rate, reaching a maximum at 190 L/min. An increasing oxygen flow rate was also accompanied by an increase in roughness and coating thickness, with a decrease in porosity, particularly notable at 190 L/min. Adhesion strength reached the maximum values for the A2 and A3 coatings under high loads. The phase composition of the coatings included WC, W2C and CoO phases irrespective of the oxygen flow rate, and their microstructure was characterized by a more homogeneous and dense structure. Thus, this study confirmed that the optimal oxygen flow rate for achieving an improved performance and tribological characteristics of 86WC-10Co-4Cr coatings is 190 L/min.

Mathematical modelling and validation of the mechanical properties of HVOF-sprayed WC-12Co coatings considering the phase composition and defects generated at different process parameters

The thermal spraying process involves many machine-based parameters or independent variables (fuel flow rate, oxygen flow rate, powder feed rate, stand-off distance and many others in the HVOF process). Any combination of these parameters produces only two measurable responses, namely, particle temperature and particle velocity. In this current work, first, the machine-based spray parameters are varied in specific ways to produce different particle temperatures at near-constant velocities and vice-versa. This approach has reduced the number of independent variables to only two. These two factors further influence the in-flight particle reactions, thereby affecting the phase composition and the microstructural defects in the as-sprayed coatings. The X-ray diffraction patterns of the as-sprayed coatings revealed the presence of W2C, W, Co3W9C4, and amorphous Co-W-C phases apart from the WC phase. The W2C and W originated owing to the decarburization of the WC phase. On the other hand, the dissolution of the carbide in molten binder led to the formation of Co3W9C4 and the amorphous Co-W-C phase. The nano-hardness of both the carbide and binder phases increased with an increase in particle temperature owing to a higher degree of decarburization and carbide dissolution respectively. The porosity was the most significant micro-structural defect present in the as-sprayed coatings. An increase in either particle temperature or velocity reduced the porosity present in the as-sprayed coatings. The mechanical properties (microhardness, elastic modulus and indentation fracture toughness) tend to improve as porosity decreases. A comprehensive mathematical model was proposed to predict the mechanical properties of as-sprayed coatings as a function of composition and defects. Finally, the process maps of mechanical properties were plotted in temperature-velocity space.

Corrosion resistance of pressure/pressureless sintered cemented carbides with/without graphene oxide in NaOH solution

The electrochemical corrosion performance of WC-Co hard alloy was studied under pressure/pressureless sintering and conditions with/without graphene oxide added. Three electrochemical testing methods were used to evaluate the corrosion behavior: open circuit potential, electrochemical impedance spectroscopy, and dynamic potential polarization. The corrosion resistance of the alloy was compared using three parameters of corrosion potential, corrosion current density, and total impedance. The corrosion mechanism was studied by observing the surface morphology of corroded alloy using scanning electron microscopy and analyzing the surface corrosion products using X-ray photoelectron spectroscopy. The results showed that pseudo-passivation phenomenon appeared in the potentiodynamic polarization curve of the hard alloy in the sodium hydroxide solution. The corrosion behavior was mainly controlled by anodic dissolution, with the dissolution of WC phase being greater than that of Co phase. The corrosion resistant properties of the pressure sintered cemented carbide are higher than that of the pressure-less sintered cemented carbide respectively in NaOH solution, mainly because pressure increases the grain size and decreases the grain boundaries of cemented carbide, which can be regarded as the dislocation wall between grains and normally attacked by the serious corrosion preferentially.

Nano-, micro- and macro-indentation tests of thermal spray WC-Ni coatings with lamellar microstructure at different particle deposition temperatures

The mechanical properties of WC-Ni coatings by HVOF thermal spraying were comprehensively evaluated by indentation tests at a wide load range of 10−1-103 N, i.e. nano-, micro- and macro-indentations. The correlation between process parameters and coating microstructure and mechanical properties was characterized via particle deposition temperature. The coating microstructure changes in reduced porosity, enhanced WC phase decomposition and better splats flattening were correlated to the particle deposition temperature rising. A porosity divergence between coating surface and cross-section was found as a quantitative anisotropy indicator to coating intrinsic lamellar microstructure formed by the splats flattening and piling up. Considering the lamellar microstructure, indentation responses on coating surface and cross-section were compared for hardness and elastic modulus evaluation below 3 N. The surface hardness is higher than that of cross-section, and both increased correlatively to the particle deposition temperature rising except for the almost constant surface hardness below 1 N. An analogous particle temperature-dependent behavior was also manifested for the elastic modulus by nano-indentation below 1 N. Interestingly, the elastic modulus by coating surface micro-indentation at 30 N presented identical particle temperature dependence to that by coating cross-section nano-indentation, both consistently representing the overall coating elastic modulus change trend verified by non-destructive ultrasonic test. Indentation fracture toughness on coating surface under 1.96 kN and on coating cross-section under 49 N was comparatively evaluated, and the values had a reverse trend of dependence on the particle deposition temperature. The particle-deposition-temperature dependent mechanical properties were interpreted by the coating intra-splats and inter-splats defects reduction with enhanced carbide-metal bonding essentially determined by the melting state of the metal binder phase, providing an insight to utilize indentation tests for characterizing thermal spray coatings.

Enhanced mechanical and tribological properties of ultrasonically assisted stir-cast AA7075 metal matrix composites in challenging corrosive environments

Aluminum-based metal matrix composites (AMMCs) find extensive applications in aerospace, defence, automotive, and various sectors on account of remarkable mechanical properties, lightweight nature, and excellent dimensional stability. In this research, AA7075 matrix material was reinforced with tungsten carbide ceramic particles with various 0, 5, 10, 15 and 20 weight percentages (wt%) with the use of Ultrasonic assisted stir casing setup. The stir casted AA7075 MMCs were subjected to XRD, SEM, and density test to investigate the presence of elements, microstructure and density. The tensile, micro hardness, and wear test were performed on AL7075 based MMCs after conducting NaCl based spray test at the condition of spray pressure of 1.2 kg cm−2, spray duration of 120 h and PH value of 8.2 to determine the wear resistance, micro hardness and Ultimate Tensile Strength. The XRD test confirmed the presence of secondary phases such as Al2Cu, W2C, and MgZn2 with Al and WC phases. The SEM test confirmed the uniform dispersion and no more cluster formation upto 15 wt% WC addition and agglomeration of WC was occurred in the addition of 20 wt% of WC. The enhancing of wt% of WC improved the corrosion resistance, Micro hardness, UTS, wear and up to 15 wt% addition and decreases by the 20 wt% WC addition. The higher tensile strength 312 MPa was obtained from AA7075/15 wt%WC composite. The lower wear rate 0.11 mg m−1 was obtained from AA7075/15 wt%WC at 1000 m sliding distance with 1.2 m s−1 sliding velocity. The improved mechanical and tribological properties were mainly depended on strengthening mechanisms such as load transfer mechanism and dislocation strengthening mechanism.

Corrosion and corrosion-friction effects induced by cutting fluid on binderless WC matrix composite and cemented carbide

The corrosion behavior of WC-4.3 wt%MgO-2wt.%ZrO2 composite in alkaline solution with 5 % oil-based cutting fluid as medium was studied by electrochemical and microstructure analysis methods. The results showed that WM2Z composite has better corrosion resistance than YG3 and YG6 in alkaline environment. A stable passivation film was formed inside the WC phase after dissolution on the surface, which was the key reason for its high corrosion resistance. However, large areas of WC phase fell off in cemented carbide. In the process of corrosion-friction coupling experiment, due to the more excellent corrosion resistance and mechanical properties of WM2Z composites, the corrosion resistance and friction properties of WM2Z composites are better than that of YG3 cemented carbide. The corrosion-friction coupling effect on WM2Z was low, and the degree of damage to the topography after the experiment was relatively light.

Effect of WC content on the microstructure and wear resistance of laser cladding AlCoCrFeNiTi0.5 high-entropy alloy coatings

AlCoCrFeNiTi0.5+x(WC) high-entropy alloy (HEA) coatings with varying WC content (x = 0, 10, 20, and 30 wt%) were prepared by laser cladding. The results of the microstructure analysis showed that the AlCoCrFeNiTi0.5 coating consisted of body-centered cubic (BCC1) and BCC2 phases, while additional TiC and W2C phases formed within the coating with the WC content reaching 20 wt% mol. The addition of WC particles acted as a barrier to grain growth, preventing grains from growing larger. Additionally, the in-situ TiC phase was distributed at the grain boundaries and further inhibited the grains growth. The grain refinement and increase in dislocation density jointly improved the ability of the coating to resist plastic deformation. Due to the addition of the WC particles, the micro-hardness and wear resistance of the coatings improved considerably. The AlCoCrFeNiTi0.5 coating with 30 wt% WC exhibited the best performance. Its hardness increased by 35.8 % and wear rate decreased by 58.2 % compared with the AlCoCrFeNiTi0.5 coating.

Evaluation of cobalt removal from polycrystalline diamond compact in the coupling mechanism of acid leaching and electrolysis

Polycrystalline diamond compact (PDC) is a widely used superhard material, and its thermal stability and wear resistance are the main factors determining its performance. The residual cobalt binder content in polycrystalline diamond (PCD) has a significant impact on the thermal stability and wear resistance of PDC. Therefore, cobalt removal treatment is required to improve the performance of PDC. The current cobalt removal methods mainly include acid leaching and electrolysis. This study proposes a novel coupling method that combines acid leaching and electrolysis for cobalt removal. Cobalt removal was conducted for 10 h under the conditions of electrolytic voltage of 12 V, direct current power supply current of 0.01 A, and sulfuric acid electrolyte concentration of 9.2 mol/L. The cobalt removal effect was evaluated using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The hardness and elastic modulus of PDC before and after cobalt removal were measured using nanoindentation experiments. The results indicate that the coupled electrolysis process effectively removes the cobalt phase in the PCD layer while retaining the WC phase. The hardness and elastic modulus of PDC decrease after the removal of cobalt binder, and the cobalt removal depth can reach 807 μm.

Fabrication and structural characterisation of ZrC-W cermet by spark plasma sintering: Application in ballistical projection

This paper describes the effect of addition of tungesten (W) when was introduced into ZrC composite forming ceramic metal-composite (MMC) and (FGMS) to improve the fracture toughness (KIC) and hardeness (Hv) of the composite ceramic-metal. ZrC and ZrC with addition of 20 % of tungesten (ZrC-W) were prepared by vacuum sintering FAST-SPS-FCT technology at the temperatures in the range of 1700–1800 °C for 400 s under pressure of 50 Mpa. Microtructural properties were investigated by X-ray diffraction and energy-dispersive spectrometry in addition scanning electron miroscopy. The investigations shows that the phase separation of the as-sintered ZrC and ZrC-20 wt%W into two phases: ZrC (dark) and (C)W (bright) indicating that the as-sintered (ZrC)W was thoroughly decomposed in tree phases ZrC, W2C and WC. The effect of the W is already illustrated. X-ray diffraction and energy-dispersive spectrometry results indicate that bright grains are W, (W)C and dark ZrC solid solution. The relative density increases with the reinforcement by W into ZrC. Fully dense ZrC and ZrC-20 vol% W ceramic metal-composite with a relative density of more than 98.8 % were obtained. The Vickers hardennes (HV), fracture toughness (KIC) and Raman spectroscopy will be performed in the near future. In addition, ballistic performance (dynamic properties by projectil persing resistance) . A finite element simulation will used to optimise the vol% W addition to obtain better mechanical properties and ballistical performance. The Analyzer of the termo-mechanical evolution within the volume of ZrC and ZrC-W specimens subjected to FAST-SPS-FCT platform (thermo-mechanical modeling under ABAQUS). Also, the ballistic performance will be evaluated using the Rosenberg model and compared with the experimental results in order to better understand the dynamic shock behavior of ceramic metal-composite (ZrC and ZrC-W) by the projectile that to be applied for body armor.

Effect of binder content and sintering time on the microstructure and mechanical properties of gradient cemented carbides with Ni binder

Replacement of Co by alternative Ni binder in gradient cemented carbide is an effective way to reduce the health concerns associated with Co powders. In the present work, gradient cemented carbides with different Ni contents and gradient sintering times were prepared by traditional powder metallurgy with a two-step sintering method. The microstructure of cemented carbide including the gradient layer formation was analyzed by XRD, SEM, EDS, TEM, and EBSD. The thickness of the gradient layer is almost proportional to the square root of sintering time, indicating that the gradient layer formation is a diffusion-controlled process. The atomic migration can be accelerated to form a thicker gradient layer with the increase of the binder content. The coherent interface of the Ti(C, N) core-rim structure for the gradient cemented carbides with Ni binder was revealed. With the increase in binder content, the average grain size of the WC phase is increased. The hardness and fracture toughness of the cemented carbides were also studied and analyzed according to the crack propagation behavior and the distribution of dislocation and stress indicated by KAM and GND. The variation of the hardness and the fracture toughness with the sintering time is mainly related to the density and the grain size of hard phases, while the change of the mechanical properties along with the Ni content probably results from the local dislocation density and the stress in the cemented carbides. The cemented carbide can obtain a good combination of hardness and fracture toughness with 10 wt% Ni gradient sintered for 2h.

Improved tribological properties of W-S-C-N film contributed by the friction-induced well crystallized thick transfer layer

Amorphous W-S-C-N lubricating films were prepared by sputtering two WS2 targets and an additional WC target in Ar&N2 atmosphere. The W-S-C-N film demonstrated a notably stable low coefficient of friction (COF) of approximately 0.01, as well as a wear rate of 1.50 × 10-7 mm3/Nm over extended sliding cycles. These characteristics indicated superior tribological properties compared to the deposited WS2, W-S-C, and W-S-N films. The formation of the friction-induced well-crystallized WS2 transfer film with its (002) basal plane parallel to the sliding surface of the counterpart ball contributed to the low friction of the W-S-C-N film. Furthermore, the embedded amorphous and nanocrystalline WC phase within the crystallized WS2-based transfer film further enhanced the stability and durability of the transfer film.

Microstructure and Properties of Ni-WC Composite Plasma Clad

aims: This study aims to improve the surface properties of 45 steel to broaden its applications. background: 45 Steel is an important material for the development of human society and civilisation,and plays an important role in human production and life. Ni-based composite coatings are widely used in metal workpieces to improve the surface properties and expand its applications. objective: In this study, Ni-WC composite coating was prepared on 45 steel substrates by plasma cladding. The microstructure, microhardness, residual stress, and corrosion resistance properties were analyzed to examine various influencing factors. method: In this study, the plasma cladding technique was employed to produce Ni-based cladding with different WC contents on 45 steel surfaces. The microstructure, phase structure, microhardness, residual stress, and corrosion resistance of Ni-based cladding coatings were investigated. result: The results showed that the coatings are made up mostly of Ni3Fe, Cr23C6, Cr7C3, WC, and W2C phases. conclusion: The microhardness of the Ni-based alloy coatings is greatly increased due to the presence of WC hard phase on the Ni matrix. The highest microhardness is more than tripling that of the substrate with the addition of 60% WC. In addition, the largest residual stress at the center of the cladding channel is more than five times higher than the substrate affected zone. The corrosion resistance of 45 steels containing Ni-based coatings increases in acidic, neutral and alkaline environments due to the formation of passivation films. other: none

Nanophase and nanostructure of tungsten carbide: The electrical explosion of a wire in a solid matrix of naphthalene and carbon nanotube

Tungsten carbides are important materials used in ceramic cements, machining tools, catalysts, sensors, and for hydrogen generation. Bulk W–C structures are highly complex; fundamental fully carburized WC and semi-carburized W2C are accompanied by structural transitions depending on the composition and temperature. The relationship between the structures, compositions, and temperatures is summarized in the W–C phase diagram. However, the high-temperature, stable, and single-crystalline nanoparticles related to the WC1-x and W2C phases formed via energetic reactions accompanied by rapid cooling rates are not easy to determine considering the bulk phase diagram, and lead to fundamental questions regarding the origin of the nanophases. In this study, we propose a draft for the W–C nanophase diagram composed of the surface and gas-phase WC, WC1-x, and W2C nanophases according to the composition and temperature. The model undergoes the process of a vapor–nanoliquid–nanophase starting from the gas-phase nucleation induced by an extremely high-temperature electrical explosion. In addition, the high-temperature reactivity and quenched nanophase, including its unique nanostructure, are related to the post-melt rheology, physical morphology, and steric hindrance of the solid matrix during an electrical explosion.

Enhancement of the Refractory Matrix Diamond-Reinforced Cutting Tool Composite with Zirconia Nano-Additive.

This paper presents the results of the experimental research on diamond-reinforced composites with WC-Co matrices enhanced with a ZrO2 additive. The samples were prepared using a modified spark plasma sintering method with a directly applied alternating current. The structure and performance of the basic composite 94 wt.%WC-6 wt.%Co was compared with the ones with ZrO2 added in proportions up to 10 wt.%. It was demonstrated that an increase in zirconia content contributed to the intense refinement of the phase components. The composite 25 wt.%Cdiamond-70.5 wt.%WC-4.5 wt.%Co consisted of a hexagonal WC phase with lattice parameters a = 0.2906 nm and c = 0.2837 nm, a cubic phase (a = 1.1112 nm), hexagonal graphite phase (a = 0.2464 nm, c = 0.6711 nm), as well as diamond grits. After the addition of zirconia nanopowder, the sintered composite contained structural WC and Co3W3C phases, amorphous carbon, tetragonal phase t-ZrO2 (a = 0.36019 nm, c = 0.5174 nm), and diamond grits-these structural changes, after an addition of 6 wt.% ZrO2 contributed to an increase in the fracture toughness by more than 20%, up to KIc = 16.9 ± 0.76 MPa·m0.5, with a negligible decrease in the hardness. Moreover, the composite exhibited an alteration of the destruction mechanism after the addition of zirconia, as well as enhanced forces holding the diamond grits in the matrix.

Microstructure and tribological properties of laser cladded TiC reinforced WC-10Co4Cr coatings at 500 °C

WC-10Co4Cr-xTiC coatings were fabricated on H13 steel by laser cladding to improve their wear resistance. The effects of TiC mass fraction on the friction-wear properties at 500 °C were investigated using a high-temperature wear tester, and the wear mechanism was discussed in detail. The results show that the WC-10Co4Cr-xTiC coatings are composed of WC, W2C, Co3W3C, Cr7C3, and TiC phases, and the porosity is reduced by the addition of TiC. The average coefficients of friction of WC-10Co4Cr-xTiC coatings are increased with the TiC mass fraction; while the wear rates are opposite, showing that the addition of TiC plays a key role in wear resistance. Moreover, the wear mechanism of WC-10Co4Cr-xTiC coatings is primary abrasive wear, slight adhesive wear, and oxidative wear.

Mechanosynthesis of TaC-WC powders under environmental conditions and their consolidation via electric arc furnace

In this study, tantalum carbide (TaC) was synthesized using an innovative approach that synergistically integrates mechanosynthesis and electric arc furnace processes. By employing high-energy ball-milling (HEBM) for 50 min under environmental conditions, TaC-WC powders were successfully synthesized, using a powder mixture of tantalum and carbon in a 1:1 stoichiometric ratio. This method yielded a composition of 72.5 wt% TaC and 27.5 wt% WC, with an average particle size of 0.7 ± 0.3 μm. The use of an electric arc furnace led to the fabrication of a highly dense material with a relative density above 98%. Notably, WC derived from the mechanical milling material served as an effective sintering aid. x-ray photoelectron Spectroscopy (XPS) results indicated the formation of metal oxides on the surface of the sample, and despite the presence of these oxides, the density of the material remained uncompromised. Furthermore, x-ray diffraction (XRD) analysis after the electric arc furnace treatment demonstrated the preservation of the TaC and WC phases. Mechanical properties, including Vickers hardness, Young’s modulus and fracture toughness were 22.8 ± 0.5 GPa under an applied load of 9.8 N, 539 GPa and 6.6 MPa m1/2, respectively. The results underscore a novel and efficient synthesis route for TaC-WC with enhanced mechanical properties and high density, which are crucial aspects for applications in ultra-high temperature ceramics.

Research on microstructure and properties of laser cladding Ti-Al-WC composite coating on TC4 surface

Abstract To improve the surface properties of TC4, laser cladding was used to prepare Ti-Al-WC composite coatings with varying WC content on the surface of TC4. XRD and SEM were used to examine the physical phase composition and microstructure of the coatings. At various WC contents, the microhardness distribution and wear friction properties of the coatings were also examined. The results revealed a strong metallurgical connection between the cladding layer and the matrix. When no WC was present, the coating was mostly formed of TiAl and Ti3Al phases; however, when WC was present, the coating also contained WC, TiC, W2C, and MAX phases, as well as a minor amount of partially dissolved WC particles. When compared to the substrate, the average hardness of the coating was increased by 1.08-1.76 times. When the WC content was 20 and the wear amount was 1.9 mg, the best wear resistance was obtained. Mainly abrasive and adhesive wear was observed.

Effect of binder phases on the microstructure and sliding wear properties of HVOF-sprayed WC-based coatings

This study aimed to evaluate the microstructure and wear properties of WC-10Co-4Cr, WC-12Co, and WC-17Co coatings on TC4 titanium alloy. The coatings were deposited using high velocity oxygen-fuel (HVOF) technique. To analyze the influence of binder phases, the coatings were thoroughly examined using scanning electron microscopy, X-ray diffractometer, microhardness tester, and friction and wear tester. The analysis of the results reveals that the primary phases in all three coatings consist mainly of WC, with smaller quantities of W2C and amorphous phases present. The WC-10Co-4Cr powder demonstrates a relatively even particle size distribution, high degree of sphericity, and rough porous surface, allowing for efficient heat absorption and uniform heat distribution, resulting in a dense coating. Notably, the WC-10Co-4Cr coating exhibits significantly smaller tungsten carbide grain size compared to the other coatings. Moreover, the microhardness of the WC-10Co-4Cr coating, measured at 1377.8 HV0.05, is significantly higher than that of the WC-12Co and WC-17Co coatings, which measured at 1258.8 HV0.05 and 1182.4 HV0.05, respectively. Additionally, the WC-10Co-4Cr coating demonstrates low friction coefficient and wear volume, indicating excellent wear resistance. Subsequently, a comprehensive analysis was conducted to determine the reasons for the relative enhancement in binder performance.

Investigation of the Influence of Powder Fraction on Tribological and Corrosion Characteristics of 86WC-10Co-4Cr Coating Obtained by HVOF Method

Samples using powders of four different fractions, 15–20 μm, 20–30 μm, 30–40 μm and 40–45 μm, were fabricated to investigate the wear resistance, corrosion resistance and tribological properties of the 86WC-10Co-4Cr coating obtained using the HVOF method. The phase composition, microstructure and elemental distribution were analyzed using X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy techniques. The hardness was measured on a Vickers microhardness tester, the friction coefficient and wear rate were investigated using a tribometer, and the corrosion resistance was evaluated on an electrochemical corrosion station. The results showed that the cross-sectional microstructure of the coating is mainly represented by multifaceted WC crystals embedded in the Co-Cr matrix and the presence of lower tungsten carbides, particularly W2C. The 15–20 μm fraction particles were subjected to superheating, contributing to the decarburization process. The 20–30 µm and 30–40 µm sized particles prevented overheating and had a more homogeneous structure. The 40–45 µm powder fractions did not reach sufficient temperature for complete melting, resulting in the formation of pores in the coating layers. The phase composition of the coatings included WC, W2C and CoO phases. According to the results of the study, it was found that the optimal powder fraction for coating the 86WC-10Co-4Cr composition with improved characteristics is the fraction of the 20–30 µm sized particles.

Effects of TaCx on the microstructure and properties of WC composites

WC-5vol%TaCx (where x = 0.5, 0.7, 0.8 and 0.9) binderless cemented carbides with different carbon vacancy contents were prepared by spark plasma sintering (SPS) at a lower sintering temperature of 1800 °C. The phase evolution, microstructure and mechanical properties of these materials were investigated. The results show that the presence of WC, W2C and (Ta1-x, Wx)Cn phases in the sintered body. The formation of (Ta1-x, Wx)Cn solid solution is attributed to the dissolution of WC into TaCx, and the existence of vacancies promotes the atomic diffusion. (Ta1-x, Wx)Cn solid solution was uniformly distributed around the WC matrix, which inhibited the WC grain growth. In terms of fracture mode, the WC-5vol%TaCx composites exhibit a combination of intergranular and transgranular fracture, with crack deflection and bridging contributing to enhanced fracture toughness. Compared to other WC-TaCx composites with varying carbon vacancy content, the WC-5vol%TaC0.8 composite possesses the smallest average particle size and highest intrinsic hardness. Additionally, a semi-coherent interface is formed between (Ta1-x, Wx)Cn and WC, leading to improved mechanical properties such as highest hardness (24.4 GPa) and fracture toughness (8.5 MPa·m1/2). The WC-5vol%TaC0.8 composite, however, exhibits the lowest oxidation onset temperature attributed to its relatively smaller grain size. The introduction of carbon vacancies serves to facilitate atom diffusion and lower the densification temperature, while also functioning as a toughening agent.