Additive manufacturing(AM)technology has emerged as a viable solution for manufacturing complexshaped WC−Co cemented carbide products,thereby expanding their applications in industries such as resource mining,equipmen...Additive manufacturing(AM)technology has emerged as a viable solution for manufacturing complexshaped WC−Co cemented carbide products,thereby expanding their applications in industries such as resource mining,equipment manufacturing,and electronic information.This review provides a comprehensive summary of the progress of AM technology in WC−Co cemented carbides.The fundamental principles and classification of AM techniques are introduced,followed by a categorization and evaluation of the AM techniques for WC−Co cemented carbides.These techniques are classified as either direct AM technology(DAM)or indirect AM technology(IDAM),depending on their inclusion of post-processes like de-binding and sintering.Through an analysis of microstructure features,the most suitable AM route for WC−Co cemented carbide products with controllable microstructure is identified as the indirect AM technology,such as binder jet printing(BJP),which integrates AM with conventional powder metallurgy.展开更多
Molybdenum carbide has shown great potential in various hydrogenation reactions,and serves as a primary active species for synthesis of ethanol from dimethyl oxalate hydrogenation process which is a crucial step in th...Molybdenum carbide has shown great potential in various hydrogenation reactions,and serves as a primary active species for synthesis of ethanol from dimethyl oxalate hydrogenation process which is a crucial step in the efficient utilization of coal resources.In this study,a molybdenum carbide catalyst with a three-dimensional mesh-like hollow structure and lattice defects was carefully designed.The MoO_(3)precursor with abundant oxygen vacancies and defects was prepared by flame spray pyrolysis,and a structural modifier,Cu,was introduced by sputtering.The Cu deposited by sputtering affected the carburization and phase evolution processes.A three-dimensional mesh-like hollow structure composed of defective molybdenum carbide is formed,with theβ-Mo_(2)C exhibiting lattice distortions and defects.This defectiveβ-Mo_(2)C exhibits high reactivity,and facilitates the C=O hydrogenation process,showing a high reactivity of 83.1%yield in the hydrogenation of dimethyl oxalate.This work provides a new approach to the design and application of molybdenum carbide catalysts.展开更多
In aerospace,BBC-Nb alloys confront notable challenges in thermal stability and toughness under cyclic fatigue at varying temperatures.Insufficient thermal stability and expedited coalescence of precipitates substanti...In aerospace,BBC-Nb alloys confront notable challenges in thermal stability and toughness under cyclic fatigue at varying temperatures.Insufficient thermal stability and expedited coalescence of precipitates substantially accelerates the degradation of alloys at elevated temperatures.Here,a Nb alloy with impressive thermal stability and mechanical properties was designed using theoretical calculations and a two-step graded heat treatment process.The superlative properties of the Nb alloy are primarily associated with the NbC hierarchical structures,i.e.,stable nanoparticles in Nb-BCC grains and discontinuous microparticles at grain boundaries(GBs).The hierarchical carbides configuration avoids continuous precipitation of carbides at GBs and preferential coarsening within the grains.The process involves precipitating ZrC nanoparticles at 1350℃,then stabilizing NbC at 1800℃ by replacing Zr with Nb.Nb-FCC nanophases enveloping NbC prevent coarsening and have strong relationships with both NbC nanoparticles and matrix.The concept of fine-tuning NbC precipitation within grains and introducing NbC at GBs with a substitution method offers a strategy for high-strength,heat-resistant materials.展开更多
In this work,we aim to develop a novel post-treatment process combining cryogenic and pulsed electric field treatment to enhance WC-Co cemented carbides.The results show a 15.62%increase in hardness from 1831.38 to 21...In this work,we aim to develop a novel post-treatment process combining cryogenic and pulsed electric field treatment to enhance WC-Co cemented carbides.The results show a 15.62%increase in hardness from 1831.38 to 2117.38 HV30,a 9.60%rise in fracture toughness from 9.06 to 9.93 MPa·m^(1/2),while the friction coefficient decreases from 0.63 to 0.47.Through the residual stress evolution,WC orientation change and the martensitic transformation of Co,and the internal enhancement mechanism of cryogenic combined with pulsed electric field treatment are revealed.The electron wind generated by the pulsed electric field can efficiently reduce the residual stress induced by cryogenic process.The evolution of residual stress promotes the base slip of WC,increasing the degree of{0001}orientation.In addition,the degree of martensitic transformation of Co intensifies,with the hcp-Co/fcc-Co ratio rising from 0.41%to 17.86%.The enhanced WC{0001}orientation and increased hcp-Co content contribute to significant improvements in hardness and wear resistance.This work provides a novel efficient enhancement strategy for ceramics and alloys,with the potential to be a mainstream strengthening method in the future.展开更多
Grain boundaries(GBs)are often known as intergranular cracking sources in alloys at high temperatures,resulting in limited high-temperature strength and ductility.Here,we propose a GB-dual-carbide(de-noted as GB-DC)st...Grain boundaries(GBs)are often known as intergranular cracking sources in alloys at high temperatures,resulting in limited high-temperature strength and ductility.Here,we propose a GB-dual-carbide(de-noted as GB-DC)strengthening strategy and have developed a high-performance(NiCoFeCr)_(99)Nb0.5 C_(0.5) high-entropy alloy(HEA)with exceptional strength-ductility synergy at 1073 K.Chain-like coherent M23 C6 carbides have been successfully introduced at GBs and remain a cube parallel crystallographic orientation with the face-centered cubic(FCC)matrix during deformation.Nano-scale NbC particles are distributed alternatively between M_(23)C_(6) carbides and inhibit their coarsening.Both strength and duc-tility of the GB-DC HEA increase dramatically at strain rates ranging from 10^(−4) to 10^(−2) s^(−1) at 1073 K,compared with those of the single-phase NiCoFeCr HEA.Specifically,yield strength of 142 MPa,ultimate tensile strength of 283 MPa,and elongation of 34%were obtained,which are twice that of the refer-ence NiCoFeCr HEA(82 MPa,172 MPa,and 18%,respectively).EBSD investigations demonstrated that chain-like carbides enhance the GB cohesion at high temperature,and TEM analysis revealed that dislo-cations can go through the coherent phase boundaries(CPBs)and activate dipoles inner M_(23)C_(6) carbides,which weakened the stress concentration in GBs.This substantially reduces the critical stress for dislo-cation generation and transmission to a stress level lower than that required for intergranular fracture.Theoretical estimation suggests that carbides result in a much higher activation energy(∼510 kJ/mol)for GB sliding and a rather low interface energy(∼101 mJ/m^(2))compared with the GB energy(1000 mJ/m^(2)),which rationalizes the enhanced GB cohesion by carbides.展开更多
Bubbles are prevalent defects on the oxidized surfaces of ultra-high temperature carbides,compromis-ing structural stability and oxidation resistance.Despite their significance,the formation mechanisms and microstruct...Bubbles are prevalent defects on the oxidized surfaces of ultra-high temperature carbides,compromis-ing structural stability and oxidation resistance.Despite their significance,the formation mechanisms and microstructural evolution of bubbles during ultra-high temperature oxidation remain inadequately understood.To address this gap,the bubble behaviors of multicomponent carbides,including(Hf,Ti)C,(Hf,Zr,Ti)C,(Hf,Zr,Ti,Ta)C,and(Hf,Zr,Ti,Nb)C,were investigated under oxidation conditions at 2500℃.The roles of various elements were elucidated through first-principles calculations.Results show that the for-mation of a dense composite oxide layer is essential for bubble generation,with the release of gaseous products serving as the primary driving force.The microstructure of the bubbles is influenced by the ma-trix composition.The addition of Ti,Ta,and Nb significantly lowers the surface energy of the shell oxides,providing preferential nucleation sites for bubbles.The progressive oxidation of Ti leads to the formation of a“TiO_(2)-TiO-HfO_(2)”multilayerstructureat thebubbletop,which evolvesintoadendriticstructurewith prolonged oxidation.Ta and Nb further modulate the size and number of bubbles by altering the compo-sition and surface energy of the shell oxides.展开更多
The high-temperature dissolution behavior of primary carbides in samples taken from GCr15 continuous-casting bloom was observed in-situ by confocal laser scanning microscopy.Equations were fitted to the dissolution ki...The high-temperature dissolution behavior of primary carbides in samples taken from GCr15 continuous-casting bloom was observed in-situ by confocal laser scanning microscopy.Equations were fitted to the dissolution kinetics of primary carbides during either heating or soaking.Dissolution of carbides proceeded in three stages(fast→slow→faster)as either temperature or holding time was increased.During the heating process and during the first and third stages of the soaking process,the original size of the carbides determined the steepness of the slope,but during the middle(“slow”)stage of the soaking process,the slope remained zero.The initial size of the carbides varied greatly,but their final dissolution temperature fell within the narrow range of 1210-1235℃,and the holding time remained within 50 min.Fractal analysis was used to study the morphological characteristics of small and medium-sized carbides during the dissolution process.According to changes in the fractal dimension before and after soaking,the carbides tended to evolve towards a more regular morphology.展开更多
The good combination of mechanical and wear properties for cemented carbides is crucial.In this work,the wear behavior of functionally graded cemented carbide(FGCC)and non-graded cemented carbide(CC),with CoNiFeCr mul...The good combination of mechanical and wear properties for cemented carbides is crucial.In this work,the wear behavior of functionally graded cemented carbide(FGCC)and non-graded cemented carbide(CC),with CoNiFeCr multi-principal-element alloy(MPEA)binder,has been investigated by performing sliding wear tests and composition characterization.The results showed that compared with CC,FGCC had higher hardness,stronger fracture toughness,better wear performance,and similar TRS.FGCCs exhibited lower wear rates(3.44×10^(−7)–6.95×10^(−6)mm^(3)/(N m))and coefficients of friction(COFs)(0.27–0.39)than CCs from RT to 600℃due to mitigation of multiple risks caused by binder removal,fragmentation and pull-out of WC grains,high-temperature oxidation and softening.In the low-temperature wear stage,the MPEA binder underwent dynamic recrystallization(DRX)and twinning deformation before removing from the surface.The binder removal caused dislocation pile-ups and stacking faults(SFs)to form under high stress,resulting in fragmentation and pull-out of WC grains.The low-temperature wear was dominated by abrasive wear and adhesive wear,with a low wear rate and a high and unstable COF.In the high-temperature wear stage,initial pitting oxidation of WC grains generated many subgrain boundaries,reducing heat transfer and exacerbating oxidation,resulting in an oxide layer enriched with WO3,Mx Oy,and MWO4.High-temperature wear was dominated by oxidation wear and high-temperature softening,with a high wear rate and a low and smooth COF.The results from the present study do not only provide theoretical guidance for an understanding of the antiwear mechanism of WC-CoNiFeCr,but also a new approach for the preparation of cemented carbides with high wear resistance.展开更多
Coarse grained WC-9Co cemented carbides with 0-1.0% TaC(mass fraction) were fabricated by HIP-sintering and gas quenching. The effects of TaC on the microstructures and mechanical properties were investigated using sc...Coarse grained WC-9Co cemented carbides with 0-1.0% TaC(mass fraction) were fabricated by HIP-sintering and gas quenching. The effects of TaC on the microstructures and mechanical properties were investigated using scanning electron microscopy(SEM), energy dispersive X-ray analysis(EDS), X-ray diffractometry(XRD) and mechanical properties tests. The results show that the maximum values of hardness and strength are HV 1124 and 2466 MPa respectively when 0.4% TaC is added. When the content of TaC is more than 0.6%, the grain size of WC is no longer affected by the amount of TaC, and(W,Ta)C occurs as well. Moreover, the strength and fracture toughness increase and the(Ta+W) content decreases with the increase of TaC content. The dependence of(Ta+W) content on the mechanical properties indicates that(Ta+W) content in Co should be decreased as low as possible to improve the mechanical properties of coarse grained WC-TaC-9Co cemented carbides with the microstructure of WC+γ two phase regions.展开更多
The influence of graphene platelets(GPLs)on the WC grain size of WC-Co-GPLs cemented carbide prepared by low-pressure sintering was investigated.The role of GPLs in refining WC grains was explored by characterizing gr...The influence of graphene platelets(GPLs)on the WC grain size of WC-Co-GPLs cemented carbide prepared by low-pressure sintering was investigated.The role of GPLs in refining WC grains was explored by characterizing grain size and phase distribution.Results show that the addition of GPLs leads to significant grain refinement of WC and the more uniform distribution of WC grain size.When the content of GPLs is 0.10wt%,the average WC grain size in the cemented carbide is 0.39μm,which is 32%lower than that in WC-Co.However,the shape of WC grains is almost unaffected,while the mean free path of Co decreases.The grain refinement of WC is attributed to the homogeneous distribution of GPLs between WC/WC and WC/Co grain boundaries,which hinders the solution and precipitation process of WC in liquid phase Co,as well as the migration and growth of WC grains.Additionally,GPLs can serve as heat transfer plates in materials to improve cooling efficiency,thus inhibiting the growth of WC grain.展开更多
The effects of prior austenite and primary carbides on the mechanical properties of a novel 2.5 GPa grade steel were investigated by treating at various solid-solution temperatures.The ultimate tensile strength and Ch...The effects of prior austenite and primary carbides on the mechanical properties of a novel 2.5 GPa grade steel were investigated by treating at various solid-solution temperatures.The ultimate tensile strength and Charpy U-notch impact energy initially increased and subsequently decreased as the solid-solution temperature rose,while the yield strength consistently decreased.The size of prior austenite grain and martensite block always increased with rising the solid-solution temperature,and austenite grain growth activation energy is 274,969 J/mol.The growth of prior austenite was restricted by primary carbides M6C and MC.The dissolution of the primary carbides not only enhanced solid-solution strengthening and secondary hardening effects but also increased the volume fraction of retained austenite.The increase in the ultimate tensile strength and Charpy U-notch impact energy was primarily attributed to the dissolution of the primary carbides M6C and MC,while the decrease was due to the increase in the size of prior austenite grain and martensite block.Exceptional combination of strength,ductility and toughness with ultimate tensile strength of 2511 MPa,yield strength of 1920 MPa,elongation of 9.5%,reduction of area of 41%and Charpy U-notch impact energy of 19.5 J was obtained when experimental steel was solid-solution treated at 1020℃.展开更多
Tungsten carbide-based(WC-based)cemented carbides are widely recognized as high-performance tool materials.Traditionally,single metals such as cobalt(Co)or nickel(Ni)serve as the binder phase,providing toughness and s...Tungsten carbide-based(WC-based)cemented carbides are widely recognized as high-performance tool materials.Traditionally,single metals such as cobalt(Co)or nickel(Ni)serve as the binder phase,providing toughness and structural integrity.Replacing this phase with high-entropy alloys(HEAs)offers a promising approach to enhancing mechanical properties and addressing sustainability challenges.However,the complex multi-element composition of HEAs complicates conventional experimental design,making it difficult to explore the vast compositional space efficiently.Traditional trial-and-error methods are time-consuming,resource-intensive,and often ineffective in identifying optimal compositions.In contrast,artificial intelligence(AI)-driven approaches enable rapid screening and optimization of alloy compositions,significantly improving predictive accuracy and interpretability.Feature selection techniques were employed to identify key alloying elements influencing hardness,toughness,and wear resistance.To enhance model interpretability,explainable artificial intelligence(XAI)techniques—SHapley Additive exPlanations(SHAP)and Local Interpretable Model-agnostic Explanations(LIME)—were applied to quantify the contributions of individual elements and uncover complex elemental interactions.Furthermore,a high-throughput machine learning(ML)–driven screening approach was implemented to optimize the binder phase composition,facilitating the discovery of HEAs with superiormechanical properties.Experimental validation demonstrated strong agreement between model predictions and measured performance,confirming the reliability of the ML framework.This study underscores the potential of integrating ML and XAI for data-driven materials design,providing a novel strategy for optimizing high-entropy cemented carbides.展开更多
As the main use of TBM(tunnel boring machine)cutter ring(DC53 steel)currently is difficult to meet the requirements of high wear resistance and high toughness synchronously in its service environment,a new HWR0 steel ...As the main use of TBM(tunnel boring machine)cutter ring(DC53 steel)currently is difficult to meet the requirements of high wear resistance and high toughness synchronously in its service environment,a new HWR0 steel with 4%Cr-3%V for TBM cutter ring has been developed to control carbides in steel.Precipitation behavior of carbides in HWR0 steel was investigated through theoretical calculation by Thermo-Calc and experimental measurement using scanning electron microscope,energy dispersive spectrometer,electron probe X-ray micro-analyzer,and laser particle size analyzer.The results show that three different carbides are precipitated during cooling.And the as-cast electroslag remelting ingot of HWR0 steel primarily consists of many blocky or strip-like MC distributed along grain boundaries,few chrysanthemum-like M_(6)C concentrated at grain boundary intersections,and a large quantity of fine M_(23)C_(6)and M_(6)C dispersed in the matrix.Compared with DC53 steel,HWR0 steel has more high-hardness carbides MC,which are discontinuously distributed at the grain boundaries,achieving the dual improvement of wear resistance and impact toughness.Cooling rates significantly influence the carbides distribution and grain size.A slower cooling rate exacerbates the segregation of alloying elements,which leads to the localized enrichment of Mo and the subsequent precipitation of M_(6)C carbides at grain boundary intersections.In contrast,faster cooling rate decreases the element segregation,promotes carbide nucleation and limits the space for carbides growth,which results in finer size and distribution of carbides and grains.Higher cooling rates yield a more homogeneous microstructure with uniform MC compositions and promote the preferential formation of M_(6)C carbides along grain boundaries,which enhances the mechanical properties.展开更多
Tantalum(Ta)alloys have been widely utilized in rocket,air-breathing engines,and airframe applications.However,traditional Ta alloys suffer from insufficient strength at ultra-high temperature,making it challenging to...Tantalum(Ta)alloys have been widely utilized in rocket,air-breathing engines,and airframe applications.However,traditional Ta alloys suffer from insufficient strength at ultra-high temperature,making it challenging to satisfy the design requirements for next-generation aerospace equipment.We report a novel strategy to design Ta alloys with superior mechanical properties by integrating the multi-principal element concept with compositionally complex carbides.By introducing multiple refractory elements and C,the resultant alloys displayed a thermally stable microstructure consisting of two phases.With the increasing C contents,the microstructure evolved from hypoeutectic to eutectic and then to hypereutectic.These varying microstructural characteristics influenced crack blunting and dislocation accumulation behaviors,leading to different softening resistance at 1600℃and plasticity at room temperature.Benefiting from the strengthening effects of solid solution and compositionally complex carbides,these alloys exhibited a high strength of~600 MPa at 1600℃,significantly superior than that of traditional Ta alloys.展开更多
The binder phase performs critically on the comprehensive properties of cemented carbides,especially the hardness(HV)and fracture toughness(K_(IC))relationship.There are strong motivations in both research community a...The binder phase performs critically on the comprehensive properties of cemented carbides,especially the hardness(HV)and fracture toughness(K_(IC))relationship.There are strong motivations in both research community and industry for developing alternative binders to Co in cemented carbide system,due to the reasons such as price instability,property degeneration,and toxicity.Herein,six kinds of high entropy alloys(HEA)including CoCrFeNiMn,CoCrFeMnAl,CoCrFeNiAl,CoCrNiMnAl,CoFeNiMnAl,and CrFeNiMnAl were employed as the alternative binder for the preparation of WC-HEA cemented carbides through mechanical alloying and two-step spark plasma sintering.The impacts of HEA on the microstructures,mechanical properties,and thermal conductivity of WC-HEA hardmetals were determined and discussed.WC-HEA hardmetals exhibited both superior HV and K_(IC)to WC-metal or WC-intermetallic cemented carbides,indicating that HEA alloys were not only harder but also tougher in comparison with traditional metal or intermetallic binders.The HEA bonded hardmetals yielded thermal conductivities much lower than that of traditional WC-Co cemented carbide.The excellent HV-K_(IC)relationship of WC-HEA facilitated the potential engineering structural application of cemented carbides.展开更多
Finite dement formulations are used to simulate the evolution of the elastoplastic response of functionally graded cemented carbides （FGCC） due to thermal loading. The geometry of specimens is an axisymmetric solid ...Finite dement formulations are used to simulate the evolution of the elastoplastic response of functionally graded cemented carbides （FGCC） due to thermal loading. The geometry of specimens is an axisymmetric solid cylinder with a two-dimensional gradient. The elastoplastic constitutive relationship is developed by constraint factors. Numerical results show that compressive stresses occur in the surface zone and tensile stresses in the cobalt rich zone when the temperature drops from the initial stress-free temperature of 800 to 0℃. The maximum value of the surface compressive stress is 254 MPa and the maximum value of the tensile stress is 252 MPa in the cobalt rich zones. When the cobalt concentration difference in the specimens is equal to or greater than 0.3, there is pronounced plastic flow in cobalt rich zone. When the temperature heats up from 0 to 800 ℃, the total plastic strain reaches 0.001 4. Plastic flow has a significant effect on the reduction of thermal stress concentration.展开更多
High temperature applications such as turbine blades for aeronautics or molten glass-shaping tools require the use of refractory metallic materials.Among the later ones,cast superalloys based on some transition metals...High temperature applications such as turbine blades for aeronautics or molten glass-shaping tools require the use of refractory metallic materials.Among the later ones,cast superalloys based on some transition metals and reinforced by MC carbides stay in good place and their metallurgy merits to be well known.This work consists in a general exploration of the as-cast microstructures which can be obtained after solidification and solid state cooling down to ambient temperature for a wide series of alloys for which the base element and the MC-former element both vary.For fixed contents in chromium and carbon contents,the compositions of a total of nineteen alloys were considered.These alloys are based on Ni,Co,Fe or Nb and the M content was each time chosen to favor the appearance of TiC,TaC,NbC,HfC or ZrC,as single carbide in a given alloy.After elaboration,metallographic samples were observed by electron microscopy to investigate the obtained microstructures.The obtained results show first that the MC carbides were in many cases successfully obtained at the expense of other possible carbides(for all Co-based alloys for example)but there are also several exceptions(notably for some Nibased alloys).Second,the obtained monocarbides have a eutectic origin and they are script-liked shaped.However they are here too some exceptions,as the rare HfC obtained in a Nb-base).In general,the results obtained in this work show that the principle of dendritic matrix combined with MC carbides with a script-like morphology is not necessarily obtained:the nature of the{base element,MC-former element}combination governs the microstructure of the alloy in its as-cast state for these particular compositions in chromium and carbon.In some cases other carbides may appear and the microstructures may be even of another type.展开更多
The morphologies and formation process of Ni-pool defects in WC?8Ni cemented carbides were studied. The SEM images show that Ni-pool generally has two kinds of morphologies: “island” in isolation and “ring” around...The morphologies and formation process of Ni-pool defects in WC?8Ni cemented carbides were studied. The SEM images show that Ni-pool generally has two kinds of morphologies: “island” in isolation and “ring” around a new phase. In the obtained samples with “ring-like Ni-pool”, WC, Ni and Ni2W4C (η phase) phases were detected in XRD patterns. Combined with SEM, EDX and XRD results, it is found that the phase in the center of the “ring-like Ni-pool” is Ni2W4C (η phase) and the main chemical components of Ni-pool are Ni, W and C. In addition, the relationships among large size Ni (agglomerated) particles, volatile impurities, pores and carbon content vs forming process of the Ni-pool defects for WC?8Ni cemented carbides are also presented and discussed.展开更多
Effects of Cr3C2,VC and La2O3 additions on the WC grain morphology,hardness and toughness of WC-10Co alloys were investigated.To intensify the grain growth driving force,nano W and nano C,instead of the conventionally...Effects of Cr3C2,VC and La2O3 additions on the WC grain morphology,hardness and toughness of WC-10Co alloys were investigated.To intensify the grain growth driving force,nano W and nano C,instead of the conventionally used WC,were used as the starting materials.To obtain a three-dimensional WC grain morphology,the natural sinter skins of the alloys were observed directly by scanning electron microscopy.It is shown that the additions have a strong ability in regulating the WC grain morphological and grain size distribution characteristics and the combinations of hardness and toughness.Due to the formation of regular and homogeneous triangular platelet WC grains,WC-10Co-0.6Cr3C2-0.06La2O3 alloy shows an excellent combination of hardness and toughness.The morphological regulation mechanism,the relationship between the WC grain morphology and the properties were discussed.展开更多
The effects of deep cryogenic treatment on the microstructure and properties of WC-11 Co cemented carbides with various carbon contents were investigated.The results show that after deep cryogenic treatment,WC grains ...The effects of deep cryogenic treatment on the microstructure and properties of WC-11 Co cemented carbides with various carbon contents were investigated.The results show that after deep cryogenic treatment,WC grains are refined into triangular prism with sound edges via the process of spheroidization,but WC grain size has no evident change compared with that of untreated alloys.The phase transformation of Co phase from α-Co（FCC） to ε-Co（HCP） is observed in the cryogenically treated alloys,which is attributed to the decrease of W solubility in the binder（Co）.Deep cryogenic treatment enhances the hardness and bending strength of the alloys,while it has no significant effects on the density and cobalt magnetic performance.展开更多
基金supported by Major Science and Technology Projects in Fujian Province,China(No.2023HZ021005)State Key Laboratory of Powder Metallurgy,Central South University,ChinaFujian Key Laboratory of Rare-earth Functional Materials,China。
文摘Additive manufacturing(AM)technology has emerged as a viable solution for manufacturing complexshaped WC−Co cemented carbide products,thereby expanding their applications in industries such as resource mining,equipment manufacturing,and electronic information.This review provides a comprehensive summary of the progress of AM technology in WC−Co cemented carbides.The fundamental principles and classification of AM techniques are introduced,followed by a categorization and evaluation of the AM techniques for WC−Co cemented carbides.These techniques are classified as either direct AM technology(DAM)or indirect AM technology(IDAM),depending on their inclusion of post-processes like de-binding and sintering.Through an analysis of microstructure features,the most suitable AM route for WC−Co cemented carbide products with controllable microstructure is identified as the indirect AM technology,such as binder jet printing(BJP),which integrates AM with conventional powder metallurgy.
文摘Molybdenum carbide has shown great potential in various hydrogenation reactions,and serves as a primary active species for synthesis of ethanol from dimethyl oxalate hydrogenation process which is a crucial step in the efficient utilization of coal resources.In this study,a molybdenum carbide catalyst with a three-dimensional mesh-like hollow structure and lattice defects was carefully designed.The MoO_(3)precursor with abundant oxygen vacancies and defects was prepared by flame spray pyrolysis,and a structural modifier,Cu,was introduced by sputtering.The Cu deposited by sputtering affected the carburization and phase evolution processes.A three-dimensional mesh-like hollow structure composed of defective molybdenum carbide is formed,with theβ-Mo_(2)C exhibiting lattice distortions and defects.This defectiveβ-Mo_(2)C exhibits high reactivity,and facilitates the C=O hydrogenation process,showing a high reactivity of 83.1%yield in the hydrogenation of dimethyl oxalate.This work provides a new approach to the design and application of molybdenum carbide catalysts.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52471025 and 51901252)the Natural Science Foundation of Hunan Province(Grant No.2023JJ30684)the Natural Science Foundation of Changsha Municipal(Grant No.kq2202091).
文摘In aerospace,BBC-Nb alloys confront notable challenges in thermal stability and toughness under cyclic fatigue at varying temperatures.Insufficient thermal stability and expedited coalescence of precipitates substantially accelerates the degradation of alloys at elevated temperatures.Here,a Nb alloy with impressive thermal stability and mechanical properties was designed using theoretical calculations and a two-step graded heat treatment process.The superlative properties of the Nb alloy are primarily associated with the NbC hierarchical structures,i.e.,stable nanoparticles in Nb-BCC grains and discontinuous microparticles at grain boundaries(GBs).The hierarchical carbides configuration avoids continuous precipitation of carbides at GBs and preferential coarsening within the grains.The process involves precipitating ZrC nanoparticles at 1350℃,then stabilizing NbC at 1800℃ by replacing Zr with Nb.Nb-FCC nanophases enveloping NbC prevent coarsening and have strong relationships with both NbC nanoparticles and matrix.The concept of fine-tuning NbC precipitation within grains and introducing NbC at GBs with a substitution method offers a strategy for high-strength,heat-resistant materials.
基金supported by the National Natural Science Foundation of China(Nos.U21A20399 and 52274407)Liaoning Province Applied Basic Research Program(No.2022JH2/101300212).
文摘In this work,we aim to develop a novel post-treatment process combining cryogenic and pulsed electric field treatment to enhance WC-Co cemented carbides.The results show a 15.62%increase in hardness from 1831.38 to 2117.38 HV30,a 9.60%rise in fracture toughness from 9.06 to 9.93 MPa·m^(1/2),while the friction coefficient decreases from 0.63 to 0.47.Through the residual stress evolution,WC orientation change and the martensitic transformation of Co,and the internal enhancement mechanism of cryogenic combined with pulsed electric field treatment are revealed.The electron wind generated by the pulsed electric field can efficiently reduce the residual stress induced by cryogenic process.The evolution of residual stress promotes the base slip of WC,increasing the degree of{0001}orientation.In addition,the degree of martensitic transformation of Co intensifies,with the hcp-Co/fcc-Co ratio rising from 0.41%to 17.86%.The enhanced WC{0001}orientation and increased hcp-Co content contribute to significant improvements in hardness and wear resistance.This work provides a novel efficient enhancement strategy for ceramics and alloys,with the potential to be a mainstream strengthening method in the future.
基金sponsored by the fund of National Natural Sci-ence Foundation of China(Grant No.52371028 and 52271097)the State Key Laboratory of Solidification Processing in NPU(Grant No.SKLSP202401)the Fundamental Research Funds for the Central Universities,HUST(No.2023JYCXJJ016).
文摘Grain boundaries(GBs)are often known as intergranular cracking sources in alloys at high temperatures,resulting in limited high-temperature strength and ductility.Here,we propose a GB-dual-carbide(de-noted as GB-DC)strengthening strategy and have developed a high-performance(NiCoFeCr)_(99)Nb0.5 C_(0.5) high-entropy alloy(HEA)with exceptional strength-ductility synergy at 1073 K.Chain-like coherent M23 C6 carbides have been successfully introduced at GBs and remain a cube parallel crystallographic orientation with the face-centered cubic(FCC)matrix during deformation.Nano-scale NbC particles are distributed alternatively between M_(23)C_(6) carbides and inhibit their coarsening.Both strength and duc-tility of the GB-DC HEA increase dramatically at strain rates ranging from 10^(−4) to 10^(−2) s^(−1) at 1073 K,compared with those of the single-phase NiCoFeCr HEA.Specifically,yield strength of 142 MPa,ultimate tensile strength of 283 MPa,and elongation of 34%were obtained,which are twice that of the refer-ence NiCoFeCr HEA(82 MPa,172 MPa,and 18%,respectively).EBSD investigations demonstrated that chain-like carbides enhance the GB cohesion at high temperature,and TEM analysis revealed that dislo-cations can go through the coherent phase boundaries(CPBs)and activate dipoles inner M_(23)C_(6) carbides,which weakened the stress concentration in GBs.This substantially reduces the critical stress for dislo-cation generation and transmission to a stress level lower than that required for intergranular fracture.Theoretical estimation suggests that carbides result in a much higher activation energy(∼510 kJ/mol)for GB sliding and a rather low interface energy(∼101 mJ/m^(2))compared with the GB energy(1000 mJ/m^(2)),which rationalizes the enhanced GB cohesion by carbides.
基金financially supported by National Natural Science Foundation of China(No.52072410).
文摘Bubbles are prevalent defects on the oxidized surfaces of ultra-high temperature carbides,compromis-ing structural stability and oxidation resistance.Despite their significance,the formation mechanisms and microstructural evolution of bubbles during ultra-high temperature oxidation remain inadequately understood.To address this gap,the bubble behaviors of multicomponent carbides,including(Hf,Ti)C,(Hf,Zr,Ti)C,(Hf,Zr,Ti,Ta)C,and(Hf,Zr,Ti,Nb)C,were investigated under oxidation conditions at 2500℃.The roles of various elements were elucidated through first-principles calculations.Results show that the for-mation of a dense composite oxide layer is essential for bubble generation,with the release of gaseous products serving as the primary driving force.The microstructure of the bubbles is influenced by the ma-trix composition.The addition of Ti,Ta,and Nb significantly lowers the surface energy of the shell oxides,providing preferential nucleation sites for bubbles.The progressive oxidation of Ti leads to the formation of a“TiO_(2)-TiO-HfO_(2)”multilayerstructureat thebubbletop,which evolvesintoadendriticstructurewith prolonged oxidation.Ta and Nb further modulate the size and number of bubbles by altering the compo-sition and surface energy of the shell oxides.
基金supported by Independent Research Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(SKLASS-2023-Z13)the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200)+1 种基金A portion of the work was performed at US National High Magnetic Field Laboratory,which is supported by the National Science Foundation(Cooperative Agreement No.DMR-1157490 and DMR-1644779)the State of Florida.Thanks also to Mary Tyler for editing.
文摘The high-temperature dissolution behavior of primary carbides in samples taken from GCr15 continuous-casting bloom was observed in-situ by confocal laser scanning microscopy.Equations were fitted to the dissolution kinetics of primary carbides during either heating or soaking.Dissolution of carbides proceeded in three stages(fast→slow→faster)as either temperature or holding time was increased.During the heating process and during the first and third stages of the soaking process,the original size of the carbides determined the steepness of the slope,but during the middle(“slow”)stage of the soaking process,the slope remained zero.The initial size of the carbides varied greatly,but their final dissolution temperature fell within the narrow range of 1210-1235℃,and the holding time remained within 50 min.Fractal analysis was used to study the morphological characteristics of small and medium-sized carbides during the dissolution process.According to changes in the fractal dimension before and after soaking,the carbides tended to evolve towards a more regular morphology.
基金financially supported by the National Key Research and Development Program of China(No.2021YFB3701800)Special funding support for the Yuelu Mountain National University Science and Technology City“Ranking the Top of the List”Research Project:(Tunnel Boring Machine High-performance Long-life Cutting Tools)the State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘The good combination of mechanical and wear properties for cemented carbides is crucial.In this work,the wear behavior of functionally graded cemented carbide(FGCC)and non-graded cemented carbide(CC),with CoNiFeCr multi-principal-element alloy(MPEA)binder,has been investigated by performing sliding wear tests and composition characterization.The results showed that compared with CC,FGCC had higher hardness,stronger fracture toughness,better wear performance,and similar TRS.FGCCs exhibited lower wear rates(3.44×10^(−7)–6.95×10^(−6)mm^(3)/(N m))and coefficients of friction(COFs)(0.27–0.39)than CCs from RT to 600℃due to mitigation of multiple risks caused by binder removal,fragmentation and pull-out of WC grains,high-temperature oxidation and softening.In the low-temperature wear stage,the MPEA binder underwent dynamic recrystallization(DRX)and twinning deformation before removing from the surface.The binder removal caused dislocation pile-ups and stacking faults(SFs)to form under high stress,resulting in fragmentation and pull-out of WC grains.The low-temperature wear was dominated by abrasive wear and adhesive wear,with a low wear rate and a high and unstable COF.In the high-temperature wear stage,initial pitting oxidation of WC grains generated many subgrain boundaries,reducing heat transfer and exacerbating oxidation,resulting in an oxide layer enriched with WO3,Mx Oy,and MWO4.High-temperature wear was dominated by oxidation wear and high-temperature softening,with a high wear rate and a low and smooth COF.The results from the present study do not only provide theoretical guidance for an understanding of the antiwear mechanism of WC-CoNiFeCr,but also a new approach for the preparation of cemented carbides with high wear resistance.
基金Project(2013zzts025)supported by the Fundamental Research Funds for the Central Universities of China
文摘Coarse grained WC-9Co cemented carbides with 0-1.0% TaC(mass fraction) were fabricated by HIP-sintering and gas quenching. The effects of TaC on the microstructures and mechanical properties were investigated using scanning electron microscopy(SEM), energy dispersive X-ray analysis(EDS), X-ray diffractometry(XRD) and mechanical properties tests. The results show that the maximum values of hardness and strength are HV 1124 and 2466 MPa respectively when 0.4% TaC is added. When the content of TaC is more than 0.6%, the grain size of WC is no longer affected by the amount of TaC, and(W,Ta)C occurs as well. Moreover, the strength and fracture toughness increase and the(Ta+W) content decreases with the increase of TaC content. The dependence of(Ta+W) content on the mechanical properties indicates that(Ta+W) content in Co should be decreased as low as possible to improve the mechanical properties of coarse grained WC-TaC-9Co cemented carbides with the microstructure of WC+γ two phase regions.
基金National Natural Science Foundation of China(51572224)Guangdong Young Creative Talents(2023KQNCX039)+2 种基金Guangdong Basic and Applied Basic Research Foundation(2023A1515110551)Innovative Team in Higher Educational Institutions of Guangdong Province(2020KCXTD039)2023 Lingnan Normal College Students Innovation and Entrepreneurship Training Program(1742)。
文摘The influence of graphene platelets(GPLs)on the WC grain size of WC-Co-GPLs cemented carbide prepared by low-pressure sintering was investigated.The role of GPLs in refining WC grains was explored by characterizing grain size and phase distribution.Results show that the addition of GPLs leads to significant grain refinement of WC and the more uniform distribution of WC grain size.When the content of GPLs is 0.10wt%,the average WC grain size in the cemented carbide is 0.39μm,which is 32%lower than that in WC-Co.However,the shape of WC grains is almost unaffected,while the mean free path of Co decreases.The grain refinement of WC is attributed to the homogeneous distribution of GPLs between WC/WC and WC/Co grain boundaries,which hinders the solution and precipitation process of WC in liquid phase Co,as well as the migration and growth of WC grains.Additionally,GPLs can serve as heat transfer plates in materials to improve cooling efficiency,thus inhibiting the growth of WC grain.
基金supported financially by National Key Research and Development Program of China(No.2022YFB3705200)Heilongjiang Province's Key Technology Project:‘Leading the Charge with Open Competition’(No.2023ZXJ04A02)Youth Program of CISRI Funding under Grant(No.S-23T60190B).
文摘The effects of prior austenite and primary carbides on the mechanical properties of a novel 2.5 GPa grade steel were investigated by treating at various solid-solution temperatures.The ultimate tensile strength and Charpy U-notch impact energy initially increased and subsequently decreased as the solid-solution temperature rose,while the yield strength consistently decreased.The size of prior austenite grain and martensite block always increased with rising the solid-solution temperature,and austenite grain growth activation energy is 274,969 J/mol.The growth of prior austenite was restricted by primary carbides M6C and MC.The dissolution of the primary carbides not only enhanced solid-solution strengthening and secondary hardening effects but also increased the volume fraction of retained austenite.The increase in the ultimate tensile strength and Charpy U-notch impact energy was primarily attributed to the dissolution of the primary carbides M6C and MC,while the decrease was due to the increase in the size of prior austenite grain and martensite block.Exceptional combination of strength,ductility and toughness with ultimate tensile strength of 2511 MPa,yield strength of 1920 MPa,elongation of 9.5%,reduction of area of 41%and Charpy U-notch impact energy of 19.5 J was obtained when experimental steel was solid-solution treated at 1020℃.
文摘Tungsten carbide-based(WC-based)cemented carbides are widely recognized as high-performance tool materials.Traditionally,single metals such as cobalt(Co)or nickel(Ni)serve as the binder phase,providing toughness and structural integrity.Replacing this phase with high-entropy alloys(HEAs)offers a promising approach to enhancing mechanical properties and addressing sustainability challenges.However,the complex multi-element composition of HEAs complicates conventional experimental design,making it difficult to explore the vast compositional space efficiently.Traditional trial-and-error methods are time-consuming,resource-intensive,and often ineffective in identifying optimal compositions.In contrast,artificial intelligence(AI)-driven approaches enable rapid screening and optimization of alloy compositions,significantly improving predictive accuracy and interpretability.Feature selection techniques were employed to identify key alloying elements influencing hardness,toughness,and wear resistance.To enhance model interpretability,explainable artificial intelligence(XAI)techniques—SHapley Additive exPlanations(SHAP)and Local Interpretable Model-agnostic Explanations(LIME)—were applied to quantify the contributions of individual elements and uncover complex elemental interactions.Furthermore,a high-throughput machine learning(ML)–driven screening approach was implemented to optimize the binder phase composition,facilitating the discovery of HEAs with superiormechanical properties.Experimental validation demonstrated strong agreement between model predictions and measured performance,confirming the reliability of the ML framework.This study underscores the potential of integrating ML and XAI for data-driven materials design,providing a novel strategy for optimizing high-entropy cemented carbides.
基金financial support of the Central Guide Local Science and Technology Development Project of Hubei Province of China(No.2023EGA008)the Wuhan Natural Science Foundation Exploration Project(Chenguang Project)(No.2024040801020309).
文摘As the main use of TBM(tunnel boring machine)cutter ring(DC53 steel)currently is difficult to meet the requirements of high wear resistance and high toughness synchronously in its service environment,a new HWR0 steel with 4%Cr-3%V for TBM cutter ring has been developed to control carbides in steel.Precipitation behavior of carbides in HWR0 steel was investigated through theoretical calculation by Thermo-Calc and experimental measurement using scanning electron microscope,energy dispersive spectrometer,electron probe X-ray micro-analyzer,and laser particle size analyzer.The results show that three different carbides are precipitated during cooling.And the as-cast electroslag remelting ingot of HWR0 steel primarily consists of many blocky or strip-like MC distributed along grain boundaries,few chrysanthemum-like M_(6)C concentrated at grain boundary intersections,and a large quantity of fine M_(23)C_(6)and M_(6)C dispersed in the matrix.Compared with DC53 steel,HWR0 steel has more high-hardness carbides MC,which are discontinuously distributed at the grain boundaries,achieving the dual improvement of wear resistance and impact toughness.Cooling rates significantly influence the carbides distribution and grain size.A slower cooling rate exacerbates the segregation of alloying elements,which leads to the localized enrichment of Mo and the subsequent precipitation of M_(6)C carbides at grain boundary intersections.In contrast,faster cooling rate decreases the element segregation,promotes carbide nucleation and limits the space for carbides growth,which results in finer size and distribution of carbides and grains.Higher cooling rates yield a more homogeneous microstructure with uniform MC compositions and promote the preferential formation of M_(6)C carbides along grain boundaries,which enhances the mechanical properties.
基金funded by the National Natural Science Foundation of China(Grant Nos.52201171 and 52225103)the Fundamental Research Funds for the Central Universities,China(Grant No.FRF-IDRY-23-001)the National Key Research and Development Program of China(Grant No.2022YFB4602101).
文摘Tantalum(Ta)alloys have been widely utilized in rocket,air-breathing engines,and airframe applications.However,traditional Ta alloys suffer from insufficient strength at ultra-high temperature,making it challenging to satisfy the design requirements for next-generation aerospace equipment.We report a novel strategy to design Ta alloys with superior mechanical properties by integrating the multi-principal element concept with compositionally complex carbides.By introducing multiple refractory elements and C,the resultant alloys displayed a thermally stable microstructure consisting of two phases.With the increasing C contents,the microstructure evolved from hypoeutectic to eutectic and then to hypereutectic.These varying microstructural characteristics influenced crack blunting and dislocation accumulation behaviors,leading to different softening resistance at 1600℃and plasticity at room temperature.Benefiting from the strengthening effects of solid solution and compositionally complex carbides,these alloys exhibited a high strength of~600 MPa at 1600℃,significantly superior than that of traditional Ta alloys.
基金supported by the National Natural Science Foundation of China(No.52375451)the Shandong Provincial Natural Science Foundation,China(Nos.ZR2023YQ052 and ZR2023ME087)+5 种基金the Shandong Provincial Technological SME Innovation Capability Promotion Project,China(No.2023TSGC0375)the Young Taishan Scholars Program of Shandong Province,China(No.tsqn202306041)the Guangdong Basic and Applied Basic Research Foundation,China(No.2023A1515010044)the Shandong Provincial Youth Innovation Team,China(No.2022KJ038)the Open project of State Key Laboratory of Solid Lubrication,China(No.LSL-22-11)Qilu Youth Scholar Project Funding of Shandong University,China.
文摘The binder phase performs critically on the comprehensive properties of cemented carbides,especially the hardness(HV)and fracture toughness(K_(IC))relationship.There are strong motivations in both research community and industry for developing alternative binders to Co in cemented carbide system,due to the reasons such as price instability,property degeneration,and toxicity.Herein,six kinds of high entropy alloys(HEA)including CoCrFeNiMn,CoCrFeMnAl,CoCrFeNiAl,CoCrNiMnAl,CoFeNiMnAl,and CrFeNiMnAl were employed as the alternative binder for the preparation of WC-HEA cemented carbides through mechanical alloying and two-step spark plasma sintering.The impacts of HEA on the microstructures,mechanical properties,and thermal conductivity of WC-HEA hardmetals were determined and discussed.WC-HEA hardmetals exhibited both superior HV and K_(IC)to WC-metal or WC-intermetallic cemented carbides,indicating that HEA alloys were not only harder but also tougher in comparison with traditional metal or intermetallic binders.The HEA bonded hardmetals yielded thermal conductivities much lower than that of traditional WC-Co cemented carbide.The excellent HV-K_(IC)relationship of WC-HEA facilitated the potential engineering structural application of cemented carbides.
基金The National Natural Science Foundation of China(No.50323008,31070517)Scientific Research Foundation of Guangxi Education Department(No.201203YB097)
文摘Finite dement formulations are used to simulate the evolution of the elastoplastic response of functionally graded cemented carbides （FGCC） due to thermal loading. The geometry of specimens is an axisymmetric solid cylinder with a two-dimensional gradient. The elastoplastic constitutive relationship is developed by constraint factors. Numerical results show that compressive stresses occur in the surface zone and tensile stresses in the cobalt rich zone when the temperature drops from the initial stress-free temperature of 800 to 0℃. The maximum value of the surface compressive stress is 254 MPa and the maximum value of the tensile stress is 252 MPa in the cobalt rich zones. When the cobalt concentration difference in the specimens is equal to or greater than 0.3, there is pronounced plastic flow in cobalt rich zone. When the temperature heats up from 0 to 800 ℃, the total plastic strain reaches 0.001 4. Plastic flow has a significant effect on the reduction of thermal stress concentration.
文摘High temperature applications such as turbine blades for aeronautics or molten glass-shaping tools require the use of refractory metallic materials.Among the later ones,cast superalloys based on some transition metals and reinforced by MC carbides stay in good place and their metallurgy merits to be well known.This work consists in a general exploration of the as-cast microstructures which can be obtained after solidification and solid state cooling down to ambient temperature for a wide series of alloys for which the base element and the MC-former element both vary.For fixed contents in chromium and carbon contents,the compositions of a total of nineteen alloys were considered.These alloys are based on Ni,Co,Fe or Nb and the M content was each time chosen to favor the appearance of TiC,TaC,NbC,HfC or ZrC,as single carbide in a given alloy.After elaboration,metallographic samples were observed by electron microscopy to investigate the obtained microstructures.The obtained results show first that the MC carbides were in many cases successfully obtained at the expense of other possible carbides(for all Co-based alloys for example)but there are also several exceptions(notably for some Nibased alloys).Second,the obtained monocarbides have a eutectic origin and they are script-liked shaped.However they are here too some exceptions,as the rare HfC obtained in a Nb-base).In general,the results obtained in this work show that the principle of dendritic matrix combined with MC carbides with a script-like morphology is not necessarily obtained:the nature of the{base element,MC-former element}combination governs the microstructure of the alloy in its as-cast state for these particular compositions in chromium and carbon.In some cases other carbides may appear and the microstructures may be even of another type.
文摘The morphologies and formation process of Ni-pool defects in WC?8Ni cemented carbides were studied. The SEM images show that Ni-pool generally has two kinds of morphologies: “island” in isolation and “ring” around a new phase. In the obtained samples with “ring-like Ni-pool”, WC, Ni and Ni2W4C (η phase) phases were detected in XRD patterns. Combined with SEM, EDX and XRD results, it is found that the phase in the center of the “ring-like Ni-pool” is Ni2W4C (η phase) and the main chemical components of Ni-pool are Ni, W and C. In addition, the relationships among large size Ni (agglomerated) particles, volatile impurities, pores and carbon content vs forming process of the Ni-pool defects for WC?8Ni cemented carbides are also presented and discussed.
基金Project (51074189) supported by the National Natural Science Foundation of ChinaProject (20100162110001) supported by Research Fund for the Doctoral Program of Higher Education of ChinaProject (2011BAE09B02) supported by the National Science & Technology Special Foundation of China
文摘Effects of Cr3C2,VC and La2O3 additions on the WC grain morphology,hardness and toughness of WC-10Co alloys were investigated.To intensify the grain growth driving force,nano W and nano C,instead of the conventionally used WC,were used as the starting materials.To obtain a three-dimensional WC grain morphology,the natural sinter skins of the alloys were observed directly by scanning electron microscopy.It is shown that the additions have a strong ability in regulating the WC grain morphological and grain size distribution characteristics and the combinations of hardness and toughness.Due to the formation of regular and homogeneous triangular platelet WC grains,WC-10Co-0.6Cr3C2-0.06La2O3 alloy shows an excellent combination of hardness and toughness.The morphological regulation mechanism,the relationship between the WC grain morphology and the properties were discussed.
基金Project(12JJ8018)supported by the Natural Science Foundation of Hunan Province,China
文摘The effects of deep cryogenic treatment on the microstructure and properties of WC-11 Co cemented carbides with various carbon contents were investigated.The results show that after deep cryogenic treatment,WC grains are refined into triangular prism with sound edges via the process of spheroidization,but WC grain size has no evident change compared with that of untreated alloys.The phase transformation of Co phase from α-Co（FCC） to ε-Co（HCP） is observed in the cryogenically treated alloys,which is attributed to the decrease of W solubility in the binder（Co）.Deep cryogenic treatment enhances the hardness and bending strength of the alloys,while it has no significant effects on the density and cobalt magnetic performance.
