In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and propert...In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and properties of the weld bead were studied.The results showed that the rotary motion of the tungsten needle transferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow characteristics.Under the action of a relatively spiraling shielding gas,arc constriction occurred,and molten pool width dropped considerably.A finer and more uniform precipitated phase in the matrix,as well as a fewer large-medium pores,were achieved in the 5A06 aluminum alloy weld metal using this modified GTAW process,which noticeably increased the bending strength and tensile strength of weld metal and the microhardness of fusion zone.展开更多
Tungsten/molybdenum alloys are widely utilized in the nuclear industry,aerospace and various other fields due to their high melting points and strength characteristics.However,poor sinterability and processability mak...Tungsten/molybdenum alloys are widely utilized in the nuclear industry,aerospace and various other fields due to their high melting points and strength characteristics.However,poor sinterability and processability make it difficult to manufacture largesize or complex-shaped parts.Hence,an in-depth study on the welding technology of tungsten/molybdenum alloys is urgent.An introduction of tungsten/molybdenum alloy welding defects and joining process was provided,along with recent advancements in brazing,spark plasma sintering diffusion bonding,electron beam welding and laser beam welding.The latest progress in alloy doping treatment applied to tungsten/molybdenum alloy dissimilar welding was also discussed,and existing welding problems were pointed out.The development prospects of weldability of tungsten/molybdenum alloy by various joining technologies were forecasted,thereby furnishing a theoretical and practical found.展开更多
Practical application of Na3SbS4(NSS)solid-state electrolyte in sodium metal batteries has been significantly hindered by poor interfacial stability and insufficient ionic conductivity.In this study,a series of dual-s...Practical application of Na3SbS4(NSS)solid-state electrolyte in sodium metal batteries has been significantly hindered by poor interfacial stability and insufficient ionic conductivity.In this study,a series of dual-site doped Na_(3-2x)Sb_(1-x)W_(x)S_(4-x)F_(x)(x=0,0.12,0.24,0.36)electrolytes through high-energy ball milling followed by high-temperature sintering is prepared,where tungsten(W)substitutes for antimony(Sb)and fluorine(F)replaces sulfur(S)in the NSS lattice.The co-doping of W and F not only broadens the interplanar spacing of NSS but also promotes the stable formation of the cubic phase of NSS,thereby effectively enhancing the transport ability of sodium ions within NSS.Among them,Na_(2.52)Sb|_(0.76)W_(0.24)S_(3.76)F_(0.24) exhibits the highest ionic conductivity of 4.45 mS·cm^(-1).Furthermore,F doping facilitates the in-situ formation of NaF between the electrolyte and metallic sodium,significantly improving interfacial stability.Electrochemical evaluation shows that the Na/Na_(2.52)Sb|_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na symmetric cell achieves a high critical current density of 1.65 mA·cm^(-2) and maintains stable sodium plating/stripping cycling for 500 h at 0.1 mA·cm^(-2).Additionally,the TiS2/Na_(2.52)Sb|_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na full cell exhibits outstanding cycling stability and rate capability.展开更多
The thermal conductivity of plasma-facing materials(PFM)exposed to intense radiation is a critical concern for the reliable usage of materials in fusion reactors.However,limited research has been performed regarding t...The thermal conductivity of plasma-facing materials(PFM)exposed to intense radiation is a critical concern for the reliable usage of materials in fusion reactors.However,limited research has been performed regarding the thermal conductivity of structures that rapidly change in a short time during collision cascade processes under irradiation.In this study,we employed the tight-binding(TB)method to investigate the electronic thermal conductivity(κ_(e))of tungsten-based systems during various cascading processes.We found thatκ_(e) values sharply decrease within the initial 0.3 picoseconds and then partially recover at a slow pace;this is closely linked to the evolution of defects and microstructural distortions.The increase in the initial kinetic energy of the primary knock-on atom and the presence of a high concentration of hydrogen atoms further decrease theκ_(e) values.Conversely,higher temperatures have a significant positive effect onκ_(e).Furthermore,the presence of a grain boundary∑5[001](130)substantially reducesκ_(e),whereas the absorption effect of point defects by the grain boundary has little influence onκ_(e) during cascades.Our findings provide a theoretical basis for evaluating changes in the thermal conductivity performance of PFMs during their usage in nuclear fusion reactors.展开更多
Using molecular dynamics methods,simulations of collision cascades in polycrystalline tungsten(W)have been conducted in this study,including different primary-knock-on atom(PKA)directions,grain sizes,and PKA energies ...Using molecular dynamics methods,simulations of collision cascades in polycrystalline tungsten(W)have been conducted in this study,including different primary-knock-on atom(PKA)directions,grain sizes,and PKA energies between 1 keV and 150 keV.The results indicate that a smaller grain size leads to more defects forming in grain boundary regions during cascade processes.The impact of high-energy PKA may cause a certain degree of distortion of the grain boundaries,which has a higher probability in systems with smaller grain sizes and becomes more pronounced as the PKA energy increases.The direction of PKA can affect the formation and diffusion pathways of defects.When the PKA direction is perpendicular to the grain boundary,defects preferentially form near the grain boundary regions;by contrast,defects are more inclined to form in the interior of the grains.These results are of great significance for comprehending the changes in the performance of polycrystalline W under the high-energy fusion environments and can provide theoretical guidance for further optimization and application of W-based plasma materials.展开更多
The distribution and competitive behaviors of phosphotungstic acid and ferric chloride in the TBP-HCl-H_(2)O system were investigated by controlling the extractant concentration and the solution environment.The result...The distribution and competitive behaviors of phosphotungstic acid and ferric chloride in the TBP-HCl-H_(2)O system were investigated by controlling the extractant concentration and the solution environment.The results revealed that phosphotungstic acid exhibited a strong affinity for TBP with decreasing TBP concentration.Higher acidity significantly improved the W extraction efficiency with TBP,and the lower Cl^(-)concentration reduced the extraction efficiency of Fe.As the organic phase approached saturation point,phosphotungstic acid competitively displaced Fe to combine with TBP.The hydrogen bond structure(P=O·HO-P-W-O)between phosphotungstic acid and TBP was characterized by FT-IR,and the salting-out effect induced by FeCl_(3) was elucidated.In summary,high acidity is beneficial for exhaustive extraction of W,and an effective W/Fe separation can be achieved by reducing the concentrations of TBP and Cl^(-).展开更多
A high-quality welding method,named plasma arc welding apparatus with rotating tungsten electrode(abbreviated as PAW-RT),was proposed in this paper.The rotation speed could be adjusted from 0 to 15000 r/min.The rotary...A high-quality welding method,named plasma arc welding apparatus with rotating tungsten electrode(abbreviated as PAW-RT),was proposed in this paper.The rotation speed could be adjusted from 0 to 15000 r/min.The rotary motion of the tungsten needle trans-ferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow charac-teristics.The influences of tungsten electrode rotation speed on PAW arc morphology,weld formation and interfacial microstructure of the final weld joints were discussed by the experimental procedures involving in-situ ablation,surfacing and butt welding.The ex-periments were conducted on Q235B steel.The results indicated that the increase of tungsten electrode rotation speed in PAW-RT contributed to improving arc eccentricity,leading to aesthetically improved welds with more uniformity.Additionally,the strength,hardness and toughness of the welded joint increased,while porosity was reduced.展开更多
Wearable sensors are pivotal for point-of-care diagnostics,yet their application in extreme conditions is rarely conducted.In this work,we present a wearable pH sensor using tungsten oxide aerogel(TOA)as the sensing m...Wearable sensors are pivotal for point-of-care diagnostics,yet their application in extreme conditions is rarely conducted.In this work,we present a wearable pH sensor using tungsten oxide aerogel(TOA)as the sensing material.With the advantages of large specific surface area,high porosity and interconnected network structures,TOA not only provides excellent pH sensing performance but also demonstrates remarkable structural and sensing stability.The potentiometric pH sensor exhibits a high sensitivity(−63.70 mV/pH),a low detectable limit(0.05)and a superior stability(maintained over 50,000 s).Integrated with a Bluetooth module,the wearable sensor achieves non-invasive and real-time pH monitoring on the human skin with minimal deviation(1.91%)compared to the commercial pH meter.More importantly,the anti-impact behaviors of the TOA-based sensing materials and chip,along with the pH wearable sensor on a pig exhibit an outstanding shock-resistance ability,with variations no more than 7.17%under an impact of 118.38 kPa.Therefore,this study shows great promise for the aerogel-based personalized health management in the extreme environment.展开更多
Semiconducting transition-metal dichalcogenides(TMDs)have garnered significant interest due to their unique structures and properties,positioning them as promising candidates for novel electronic and optoelectronic de...Semiconducting transition-metal dichalcogenides(TMDs)have garnered significant interest due to their unique structures and properties,positioning them as promising candidates for novel electronic and optoelectronic devices.However,the performance of TMDs-based devices is hampered by the suboptimal quality of metal electrodes contacting the atomically thin TMDs layers.Understanding the mechanisms that influence contact quality is crucial for advancing TMDs devices.In this study,we investigated the conductive properties of tungsten selenide(WSe_(2))-based devices with different film thicknesses.Using the transmission line method,a negative correlation between contact resistance and film thickness in multi-electrode devices was revealed.Additionally,repeatability tests conducted at varied temperatures indicated enhanced device stability with increasing film thickness.Theoretical analysis,supported by thermionic emission theory and thermal simulations,suggests that the degradation in electrical properties is primarily due to the thermal effect at the contact interface.Furthermore,we found that van der Waals contacts could mitigate the thermal effect through a metal transfer method.Our findings elucidate the critical role of contact resistance in the electronic performance of 2D material-based field-effect transistors(FETs),which further expands their potential in the next generation of electronic and optoelectronic devices.展开更多
Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance...Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance efficiency of such devices,yet the underlying mecha-nism,especially the roles of optical-ly dark triplets and spatially sepa-rated charge transfer states,is poorly understood.In the present work,we obtain the struc-tures of distinct excited states and investigate how they are involved in the charge transfer process at the Pd-octaethylporphyrin(PdOEP)and WS_(2) interface in terms of their energies and couplings.The results show that electron transfer from the triplet PdOEP formed via intersystem crossing prevails over direct electron transfer from the singlet(two orders of magnitude faster).Further analysis reveals that the relatively higher rate of triplet electron transfer compared to singlet electron transfer is mainly attributed to a smaller reorganization energy,which is dominated by the out-of-plane vibrations of the organic component.The work emphasizes the important roles of the optically dark triplets in the electron transfer of the PdOEP@WS_(2) heterostructure,and provides valuable theoretical insights for further improv-ing the optoelectronic performance of TMD-based devices.展开更多
Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-dope...Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-doped cobalt molybdate(WDCMO)catalyst was synthesized for efficient and durable OER under neutral electrolyte.It is demonstrated that catalyst reconstruction is suppressed by W doping,which stabilizes the Co-O-Mo point-to-point connection in CoMoO_(4) architecture and stimulates to a lower valence state of active sites over the surface phase.Thereby,the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER.Meanwhile,the WDCMO catalyst promotes charge transfer and optimizes*OH intermediate adsorption,which improves reaction kinetics and intrinsic activity.Consequently,the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^(-2) in neutral electrolyte with an improvement of 182 mV compared with CoMoO4 electrode.Furthermore,W doping significantly improves the electrode stability from 50 h to more than 320 h,with a suppressive potential attenuation from 2.82 to 0.29 mV h^(-1).This work will shed new light on designing rational electrocatalysts for neutral OER.展开更多
Quartz vein-type tungsten deposits are a common W deposit type.Their ore vein distribution was previously considered to be controlled by regional horizontal tectonic stress.In this paper,14 tungsten deposits with fan-...Quartz vein-type tungsten deposits are a common W deposit type.Their ore vein distribution was previously considered to be controlled by regional horizontal tectonic stress.In this paper,14 tungsten deposits with fan-shaped mineralization in SE China are summarized,and the relations between their ore veins and granite and the ore-forming structural stress field are analyzed.These deposits have a post-magmatic hydrothermal genesis and involve the formation of two sets of veins with similar strike and opposite dips at the top of the ore-causative granite bodies,forming a vertical fan-shaped profile.Their ore veins were coeval with the underlying granite bodies,and generally extend along the long axis of the granite.In such fan-shaped ore formation,the stress is highly focused at the top of the granite and gradually weakens outward.The maximum principal stress(σ1)is perpendicular to the granite contact surface,and radiates outward from the pluton.Meanwhile,the minimum principal stress(σ3)forms an arc-shaped band parallel to the contact surface.Our findings,together with published numerical modeling indicate that the emplacement dynamics of granitic magma(rather than regional horizontal tectonic stress)are essential controls on the distribution of ore veins in quartz vein-type tungsten deposits.展开更多
Si-containing Mg alloys solidified at conventional rates often contain coarse and sharp Mg_(2)Si phases,which can result in inferior material properties.In this study,Mg-6wt.%Si(Mg-6Si)alloy was prepared by wire arc a...Si-containing Mg alloys solidified at conventional rates often contain coarse and sharp Mg_(2)Si phases,which can result in inferior material properties.In this study,Mg-6wt.%Si(Mg-6Si)alloy was prepared by wire arc additive manufacturing(WAAM),employing the gas tungsten arc welding technique with rapid cooling.The microstructures and mechanical properties of the WAAM alloy were investigated and compared with those of the as-cast samples produced using a metal mold.The results indicate that the WAAM Mg-6Si is harder and stronger than the as-cast samples.The microhardness of the WAAM Mg-6Si increases by 36.6% in comparison to that of as-cast Mg-6Si alloy.Furthermore,the average tensile strengths at room temperature and 150℃ increases by 63.4% and 21.3%,respectively.WAAM refines both the Mg_(2)Si phase and the overall grains,resulting in a homogeneous morphology and improved mechanical properties.The granular Mg_(2)Si phase,characterized by fine particles with a diffused distribution,shows a significant increase in concentration.The acicular Mg_(2)Si phase is distributed along the grain boundaries,and its concentration significantly decreases.The average grain size of the Mg_(2)Si phase is about 9.20μm,about 5 times smaller.The refinement and distribution of the granular Mg_(2)Si phase,as well as the reduction in the amount of needle-like Mg_(2)Si particles,are the key factors for improving the mechanical properties of WAAM Mg-6Si alloy.展开更多
Tungsten is considered the most promising plasma-facing material for fusion reactors with exceptional performance.Under certain conditions,activated tungsten dust can be generated through plasma–wall interactions and...Tungsten is considered the most promising plasma-facing material for fusion reactors with exceptional performance.Under certain conditions,activated tungsten dust can be generated through plasma–wall interactions and released into the atmosphere.Activated tungsten migrates downward in the soil after atmospheric deposition.However,effective methods for evaluating the environmental dose of gamma rays emitted by activated tungsten are still lacking.Consequently,a method for evaluating the air-absorbed dose rate of activated tungsten dust was proposed considering soil attenuation.Key parameters including the mass attenuation coefficient and energy absorption build-up factor were determined for the main gamma ray energies of radionuclides within the activated tungsten dust.Additionally,air-absorbed dose rates were calculated by assuming that radioactive sources were located at different soil depths and radii.It was found that a soil depth of 50 cm significantly attenuated the environmental dose by 99.9%,whereas the air-absorbed dose rates within the horizontal distance of 500 cm accounted for 91%of the total dose rate.Therefore,this study underscored the importance of soil attenuation in environmental dose assessments,which must be carefully re-examined for the safety analysis of fusion reactors.展开更多
LiNiO_(2)(LNO)is one of the most promising cathode materials for lithium-ion batteries.Tungsten element in enhancing the stability of LNO has been researched extensively.However,the understanding of the specific dopin...LiNiO_(2)(LNO)is one of the most promising cathode materials for lithium-ion batteries.Tungsten element in enhancing the stability of LNO has been researched extensively.However,the understanding of the specific doping process and existing form of W are still not perfect.This study proposes a lithium-induced grain boundary phase W doping mechanism.The results demonstrate that the introduced W atomsfirst react with the lithium source to generate a Li–W–O phase at the grain boundary of primary particles.With the increase of lithium ratio,W atoms gradually diffuse from the grain boundary phase to the interior layered structure to achieve W doping.The feasibility of grain boundary phase doping is verified byfirst principles calculation.Furthermore,it is found that the Li2WO4 grain boundary phase is an excellent lithium ion conductor,which can protect the cathode surface and improve the rate performance.The doped W can alleviate the harmful H2↔H3 phase transition,thereby inhibiting the generation of microcracks,and improving the electrochemical performance.Consequently,the 0.3 wt%W-doped sample provides a significant improved capacity retention of 88.5%compared with the pristine LNO(80.7%)after 100 cycles at 2.8–4.3 V under 1C.展开更多
Two-dimensional(2D)transition metal dichalcogenides(TMDs),which allow atomic-scale manipulation,have supe-rior electrical and optical properties that challenge the limits of traditional bulk semiconductors like silico...Two-dimensional(2D)transition metal dichalcogenides(TMDs),which allow atomic-scale manipulation,have supe-rior electrical and optical properties that challenge the limits of traditional bulk semiconductors like silicon^([1,2]).As a repre-sentative TMD and a promising 2D channel material for high-performance,scalable p-type transistors,tungsten diselenide(WSe_(2))has attracted considerable academic and industrial interest for its potential in advanced complementary metal−oxide−semiconductor(CMOS)logic technology and in extending Moore’s Law^([3−7]).展开更多
This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double...This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.展开更多
A new two-step spark plasma sintering(TSS)process with low-temperature pre-sintering and high-temperature final sintering has been successfully applied to prepare the tungsten-particle(Wp)-reinforced bulk metallic gla...A new two-step spark plasma sintering(TSS)process with low-temperature pre-sintering and high-temperature final sintering has been successfully applied to prepare the tungsten-particle(Wp)-reinforced bulk metallic glass composites(Wp/BMGCs).Compared to normal spark plasma sintering(NS),the densification rate and relative density of Wp/BMGCs can be improved by selecting TSS with appropriate sintering pressure in the low temperature pre-sintering stage.However,the compressive strength and plastic strain of 30%Wp/BMGCs prepared by TSS are both higher than those of the samples prepared by NS.The TSS process can significantly enhance the compressive strength of 30%Wp/BMGCs by 12%and remarkably increase the plastic strain by 50%,while the trend is completely opposite for 50%Wp/BMGCs.Quasi-in situ experiments and finite element simulations reveal that uneven temperature distribution among particles during low-temperature pre-sintering causes local overheating at contact points between particles,accelerating formation of sintering neck between particles and plastic deformation of Wp.When the volume fraction of Wp is low,TSS can improve the interface bonding between particles by increasing the number of sintering necks.This makes the fracture mode of Wp/BMGCs being predominantly transgranular fracture.However,as the volume fraction of Wp increases,the adverse effects of Wp plastic deformation are becoming more and more prominent.The aggregated Wp tends to form a solid"cage structure"that hinders the bonding between particles at the interface;correspondingly,the fracture behavior of Wp/BMGCs is mainly dominated by intergranular fracture.Additionally,reducing the sintering pressure during the low-temperature pre-sintering stage of TSS has been shown to effectively decrease plastic deformation in Wp,resulting in a higher degree of densification and better mechanical properties.展开更多
The formation and evolution of M_(6)C carbides in high-W superalloy following solution treatment was investigated at different temperatures.Initially,during solid solution treatment,MC and M_(6)C carbides was precipit...The formation and evolution of M_(6)C carbides in high-W superalloy following solution treatment was investigated at different temperatures.Initially,during solid solution treatment,MC and M_(6)C carbides was precipitated in the alloy.As the temperature increased,the morphology of M_(6)C carbides transitioned from granular to needle-like.During the solution treatment at 1255℃,the MC carbides degraded and transformed into M_(6)C carbides,forming a symbiotic relationship between them.Nonetheless,no clear orientation relationship was observed between the two types of carbides.After further increasing the temperature to 1270℃,the precipitation of needle-like M_(6)C carbides in the dendrite arm was confirmed.This was supported by electron probe X-ray micro-analyzer and selected area electron diffraction patterns.Subsequently,a detailed examination of the three-dimensional morphology and orientation relationship of the needle-like phase with the matrix was carried out using focused-ion-beam and transmission electron microscopy techniques.The results indicated that the flat interface of the needle phase exhibited a specific orientation relationship with the matrix.However,in the three-dimensional plane,the interfaces between the needle-like phase and the matrix were not straight.Furthermore,no clear orientation relationship between the non-straight interfaces and the matrix was observed.As the solution temperature increased,the tensile properties at room temperature progressively decreased,while the stress rupture properties peaked at 1260℃,suggesting that the alloy demonstrated its optimal comprehensive performance at this temperature.A subsequent analysis was conducted on the longitudinal section of the fracture using electron backscattered diffraction.The results showed a noticeable concentration of stress at the interface between MC and M_(6)C carbides,which ultimately led to crack initiation at this interface.In addition,as the solid solution temperature increased,the quantity of symbiotic phases also increased.This phenomenon led to the initiation of cracks at multiple locations,which then propagated and interconnected.As a consequence,the tensile properties and stress rupture life of the alloy progressively deteriorated.展开更多
The Xingluokeng deposit is the largest gran-ite-related tungsten deposit within the Wuyi metallogenic belt in South China.The Xingluokeng intrusion primarily consists of porphyritic biotite granite,biotite granite,and...The Xingluokeng deposit is the largest gran-ite-related tungsten deposit within the Wuyi metallogenic belt in South China.The Xingluokeng intrusion primarily consists of porphyritic biotite granite,biotite granite,andfine-grained granite.The deposit is represented by veinlet-disseminated mineralization with K-feldspathization and biotitization,alongside quartz-vein mineralization with gre-isenization and sericitization.This study investigates in-situ analyses of quartz compositions from both the intrusion and hydrothermal veinlets and veins.Trace element correlations indicate that trivalent Al^(3+)and Fe^(3+)replace Si^(4+)within the quartz lattice,with monovalent cations(such as Li^(+),Na^(+),and K^(+))primarily serving as charge compensators.Low Ge/Al ratios(<0.013)of quartz from granites suggest a mag-matic origin.The low Al/Ti and Ge/Ti ratios,accompanied by high Ti contents in quartz,suggest that the porphyritic biotite granite and biotite granite are characterized by rela-tively low levels of differentiation and high crystallization temperatures.In contrast,thefine-grained granite exhibits a higher degree of fractionation,lower crystallization tem-peratures,and a closer association with tungsten miner-alization.Ti contents in quartz from quartz veins indicate Qz-Ⅰformed at temperatures above 400°C,while Qz-Ⅱto Qz-Ⅴformed at temperatures below 350°C.Variations in different generations of quartz,as indicated by Al content and(Al+Fe)/(Li+Na+K)ratio,suggest that Qz-Ⅰprecipi-tated from a less acidicfluid with a stable pH,whereas Qz-Ⅱto Qz-Ⅴoriginated from a more acidicfluid with notable pH variations.Consequently,alkaline alteration and acidic alteration supplied the essential Ca and Fe for the precipita-tion of scheelite and wolframite,respectively,highlighting a critical mechanism in tungsten mineralization at the Xin-gluokeng deposit.展开更多
基金supported by National Natural Science Foundation of China(52175305)National Natural Science Foundation of China(U22B20127)Taishan Scholars Project(tstp20230618).
文摘In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and properties of the weld bead were studied.The results showed that the rotary motion of the tungsten needle transferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow characteristics.Under the action of a relatively spiraling shielding gas,arc constriction occurred,and molten pool width dropped considerably.A finer and more uniform precipitated phase in the matrix,as well as a fewer large-medium pores,were achieved in the 5A06 aluminum alloy weld metal using this modified GTAW process,which noticeably increased the bending strength and tensile strength of weld metal and the microhardness of fusion zone.
基金National Natural Science Foundation of China(52071165,52475347)National Program of Foreign Experts of China(G2023026003L)+4 种基金China Postdoctoral Fund(2023M740475)Program for Science&Technology Innovation Talents in Universities of Henan Province,China(22HASTIT026)Program for the Top Young Talents of Henan Province,China,Frontier Exploration Projects of Longmen Laboratory,China(LMQYTSKT016)Key Scientific Research Projects of Colleges and Universities in Henan Province,China(24A460008)Key Science and Technology Project of Henan Province,China(242102220064,222102230111)。
文摘Tungsten/molybdenum alloys are widely utilized in the nuclear industry,aerospace and various other fields due to their high melting points and strength characteristics.However,poor sinterability and processability make it difficult to manufacture largesize or complex-shaped parts.Hence,an in-depth study on the welding technology of tungsten/molybdenum alloys is urgent.An introduction of tungsten/molybdenum alloy welding defects and joining process was provided,along with recent advancements in brazing,spark plasma sintering diffusion bonding,electron beam welding and laser beam welding.The latest progress in alloy doping treatment applied to tungsten/molybdenum alloy dissimilar welding was also discussed,and existing welding problems were pointed out.The development prospects of weldability of tungsten/molybdenum alloy by various joining technologies were forecasted,thereby furnishing a theoretical and practical found.
文摘Practical application of Na3SbS4(NSS)solid-state electrolyte in sodium metal batteries has been significantly hindered by poor interfacial stability and insufficient ionic conductivity.In this study,a series of dual-site doped Na_(3-2x)Sb_(1-x)W_(x)S_(4-x)F_(x)(x=0,0.12,0.24,0.36)electrolytes through high-energy ball milling followed by high-temperature sintering is prepared,where tungsten(W)substitutes for antimony(Sb)and fluorine(F)replaces sulfur(S)in the NSS lattice.The co-doping of W and F not only broadens the interplanar spacing of NSS but also promotes the stable formation of the cubic phase of NSS,thereby effectively enhancing the transport ability of sodium ions within NSS.Among them,Na_(2.52)Sb|_(0.76)W_(0.24)S_(3.76)F_(0.24) exhibits the highest ionic conductivity of 4.45 mS·cm^(-1).Furthermore,F doping facilitates the in-situ formation of NaF between the electrolyte and metallic sodium,significantly improving interfacial stability.Electrochemical evaluation shows that the Na/Na_(2.52)Sb|_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na symmetric cell achieves a high critical current density of 1.65 mA·cm^(-2) and maintains stable sodium plating/stripping cycling for 500 h at 0.1 mA·cm^(-2).Additionally,the TiS2/Na_(2.52)Sb|_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na full cell exhibits outstanding cycling stability and rate capability.
基金supported by the Collaborative Innovation Program of Hefei Science Center of CAS(No.2022HSC-CIP007)。
文摘The thermal conductivity of plasma-facing materials(PFM)exposed to intense radiation is a critical concern for the reliable usage of materials in fusion reactors.However,limited research has been performed regarding the thermal conductivity of structures that rapidly change in a short time during collision cascade processes under irradiation.In this study,we employed the tight-binding(TB)method to investigate the electronic thermal conductivity(κ_(e))of tungsten-based systems during various cascading processes.We found thatκ_(e) values sharply decrease within the initial 0.3 picoseconds and then partially recover at a slow pace;this is closely linked to the evolution of defects and microstructural distortions.The increase in the initial kinetic energy of the primary knock-on atom and the presence of a high concentration of hydrogen atoms further decrease theκ_(e) values.Conversely,higher temperatures have a significant positive effect onκ_(e).Furthermore,the presence of a grain boundary∑5[001](130)substantially reducesκ_(e),whereas the absorption effect of point defects by the grain boundary has little influence onκ_(e) during cascades.Our findings provide a theoretical basis for evaluating changes in the thermal conductivity performance of PFMs during their usage in nuclear fusion reactors.
基金Project supported by the National MCF Energy Research and Development Program of China(Grant No.2018YFE0308101)the National Key Research and Development Program of China(Grant No.2018YFB0704000)+1 种基金the Suqian Science and Technology Program(Grant No.K202337)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.23KJD490001).
文摘Using molecular dynamics methods,simulations of collision cascades in polycrystalline tungsten(W)have been conducted in this study,including different primary-knock-on atom(PKA)directions,grain sizes,and PKA energies between 1 keV and 150 keV.The results indicate that a smaller grain size leads to more defects forming in grain boundary regions during cascade processes.The impact of high-energy PKA may cause a certain degree of distortion of the grain boundaries,which has a higher probability in systems with smaller grain sizes and becomes more pronounced as the PKA energy increases.The direction of PKA can affect the formation and diffusion pathways of defects.When the PKA direction is perpendicular to the grain boundary,defects preferentially form near the grain boundary regions;by contrast,defects are more inclined to form in the interior of the grains.These results are of great significance for comprehending the changes in the performance of polycrystalline W under the high-energy fusion environments and can provide theoretical guidance for further optimization and application of W-based plasma materials.
基金supported by the National key R&D Program of China(No.2022YFC2905105)the National Natural Science Foundation of China(No.72088101)。
文摘The distribution and competitive behaviors of phosphotungstic acid and ferric chloride in the TBP-HCl-H_(2)O system were investigated by controlling the extractant concentration and the solution environment.The results revealed that phosphotungstic acid exhibited a strong affinity for TBP with decreasing TBP concentration.Higher acidity significantly improved the W extraction efficiency with TBP,and the lower Cl^(-)concentration reduced the extraction efficiency of Fe.As the organic phase approached saturation point,phosphotungstic acid competitively displaced Fe to combine with TBP.The hydrogen bond structure(P=O·HO-P-W-O)between phosphotungstic acid and TBP was characterized by FT-IR,and the salting-out effect induced by FeCl_(3) was elucidated.In summary,high acidity is beneficial for exhaustive extraction of W,and an effective W/Fe separation can be achieved by reducing the concentrations of TBP and Cl^(-).
基金supported by the National Natural Science Foundation of China(U22B20127)the National Natural Science Foundation of China(52175305)Taishan Scholars Project(tstp20230618).
文摘A high-quality welding method,named plasma arc welding apparatus with rotating tungsten electrode(abbreviated as PAW-RT),was proposed in this paper.The rotation speed could be adjusted from 0 to 15000 r/min.The rotary motion of the tungsten needle trans-ferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow charac-teristics.The influences of tungsten electrode rotation speed on PAW arc morphology,weld formation and interfacial microstructure of the final weld joints were discussed by the experimental procedures involving in-situ ablation,surfacing and butt welding.The ex-periments were conducted on Q235B steel.The results indicated that the increase of tungsten electrode rotation speed in PAW-RT contributed to improving arc eccentricity,leading to aesthetically improved welds with more uniformity.Additionally,the strength,hardness and toughness of the welded joint increased,while porosity was reduced.
基金supported by the National Natural Science Foundation of China(Nos.22374119 and 22274127)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(No.2021-QZ-01)+1 种基金the Key Project of Natural Science Fund of Shaanxi Province(Nos.2023-JC-ZD-06 and 2024JC-YBQN-0636)the Open Project of the State Key Laboratory of Transducer Technology(No.SKT2307).
文摘Wearable sensors are pivotal for point-of-care diagnostics,yet their application in extreme conditions is rarely conducted.In this work,we present a wearable pH sensor using tungsten oxide aerogel(TOA)as the sensing material.With the advantages of large specific surface area,high porosity and interconnected network structures,TOA not only provides excellent pH sensing performance but also demonstrates remarkable structural and sensing stability.The potentiometric pH sensor exhibits a high sensitivity(−63.70 mV/pH),a low detectable limit(0.05)and a superior stability(maintained over 50,000 s).Integrated with a Bluetooth module,the wearable sensor achieves non-invasive and real-time pH monitoring on the human skin with minimal deviation(1.91%)compared to the commercial pH meter.More importantly,the anti-impact behaviors of the TOA-based sensing materials and chip,along with the pH wearable sensor on a pig exhibit an outstanding shock-resistance ability,with variations no more than 7.17%under an impact of 118.38 kPa.Therefore,this study shows great promise for the aerogel-based personalized health management in the extreme environment.
基金supported by the Science and Technology Innovation Council of Shenzhen(No.KQTD20170810105439418)the National Key R&D Project from Minister of Science and Technology,China(No.2021YFB3200304)+2 种基金National Natural Science Foundation of China(Nos.6237129,52125205,U20A20166,61805015 and 61804011)the Natural Science Foundation of Beijing Municipality(No.Z180011)the Fundamental Research Funds for the Central Universities.
文摘Semiconducting transition-metal dichalcogenides(TMDs)have garnered significant interest due to their unique structures and properties,positioning them as promising candidates for novel electronic and optoelectronic devices.However,the performance of TMDs-based devices is hampered by the suboptimal quality of metal electrodes contacting the atomically thin TMDs layers.Understanding the mechanisms that influence contact quality is crucial for advancing TMDs devices.In this study,we investigated the conductive properties of tungsten selenide(WSe_(2))-based devices with different film thicknesses.Using the transmission line method,a negative correlation between contact resistance and film thickness in multi-electrode devices was revealed.Additionally,repeatability tests conducted at varied temperatures indicated enhanced device stability with increasing film thickness.Theoretical analysis,supported by thermionic emission theory and thermal simulations,suggests that the degradation in electrical properties is primarily due to the thermal effect at the contact interface.Furthermore,we found that van der Waals contacts could mitigate the thermal effect through a metal transfer method.Our findings elucidate the critical role of contact resistance in the electronic performance of 2D material-based field-effect transistors(FETs),which further expands their potential in the next generation of electronic and optoelectronic devices.
基金supported by the Fundamental Re-search Funds for the Central Universities(Ganglong Cui)and National Key Research and Development Pro-gram of China(No.2021YFA1500703 to Ganglong Cui)National Natural Science Foundation of China(No.22103067 to Xiao-Ying Xie)and Natural Science Foundation of Shandong Province(No.ZR2021QB105 to Xiao-Ying Xie).
文摘Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance efficiency of such devices,yet the underlying mecha-nism,especially the roles of optical-ly dark triplets and spatially sepa-rated charge transfer states,is poorly understood.In the present work,we obtain the struc-tures of distinct excited states and investigate how they are involved in the charge transfer process at the Pd-octaethylporphyrin(PdOEP)and WS_(2) interface in terms of their energies and couplings.The results show that electron transfer from the triplet PdOEP formed via intersystem crossing prevails over direct electron transfer from the singlet(two orders of magnitude faster).Further analysis reveals that the relatively higher rate of triplet electron transfer compared to singlet electron transfer is mainly attributed to a smaller reorganization energy,which is dominated by the out-of-plane vibrations of the organic component.The work emphasizes the important roles of the optically dark triplets in the electron transfer of the PdOEP@WS_(2) heterostructure,and provides valuable theoretical insights for further improv-ing the optoelectronic performance of TMD-based devices.
文摘Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-doped cobalt molybdate(WDCMO)catalyst was synthesized for efficient and durable OER under neutral electrolyte.It is demonstrated that catalyst reconstruction is suppressed by W doping,which stabilizes the Co-O-Mo point-to-point connection in CoMoO_(4) architecture and stimulates to a lower valence state of active sites over the surface phase.Thereby,the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER.Meanwhile,the WDCMO catalyst promotes charge transfer and optimizes*OH intermediate adsorption,which improves reaction kinetics and intrinsic activity.Consequently,the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^(-2) in neutral electrolyte with an improvement of 182 mV compared with CoMoO4 electrode.Furthermore,W doping significantly improves the electrode stability from 50 h to more than 320 h,with a suppressive potential attenuation from 2.82 to 0.29 mV h^(-1).This work will shed new light on designing rational electrocatalysts for neutral OER.
基金funded by the National Key Research&Development Program of China(No.2021YFC2900100)the Guangxi Natural Science Foundation(No.2022GXNSFFA035025)+3 种基金the Chinese National Natural Science Foundation(No.42372099)the China Geological Survey(No.DD20190379)the Science&Technology Fundamental Resources Investigation Program(No.2022FY101800)the Major Talent Program of Guangxi Zhuang Autonomous Region,and the Innovation Project of Guangxi Graduate Education(No.YCSW2023345)。
文摘Quartz vein-type tungsten deposits are a common W deposit type.Their ore vein distribution was previously considered to be controlled by regional horizontal tectonic stress.In this paper,14 tungsten deposits with fan-shaped mineralization in SE China are summarized,and the relations between their ore veins and granite and the ore-forming structural stress field are analyzed.These deposits have a post-magmatic hydrothermal genesis and involve the formation of two sets of veins with similar strike and opposite dips at the top of the ore-causative granite bodies,forming a vertical fan-shaped profile.Their ore veins were coeval with the underlying granite bodies,and generally extend along the long axis of the granite.In such fan-shaped ore formation,the stress is highly focused at the top of the granite and gradually weakens outward.The maximum principal stress(σ1)is perpendicular to the granite contact surface,and radiates outward from the pluton.Meanwhile,the minimum principal stress(σ3)forms an arc-shaped band parallel to the contact surface.Our findings,together with published numerical modeling indicate that the emplacement dynamics of granitic magma(rather than regional horizontal tectonic stress)are essential controls on the distribution of ore veins in quartz vein-type tungsten deposits.
基金supported by the National Natural Science Foundation of China(Grant Nos.52001037,U2037601,and U21A2048)the Science and Technology Program of Guangzhou,China(Grant No.2022BLC003).
文摘Si-containing Mg alloys solidified at conventional rates often contain coarse and sharp Mg_(2)Si phases,which can result in inferior material properties.In this study,Mg-6wt.%Si(Mg-6Si)alloy was prepared by wire arc additive manufacturing(WAAM),employing the gas tungsten arc welding technique with rapid cooling.The microstructures and mechanical properties of the WAAM alloy were investigated and compared with those of the as-cast samples produced using a metal mold.The results indicate that the WAAM Mg-6Si is harder and stronger than the as-cast samples.The microhardness of the WAAM Mg-6Si increases by 36.6% in comparison to that of as-cast Mg-6Si alloy.Furthermore,the average tensile strengths at room temperature and 150℃ increases by 63.4% and 21.3%,respectively.WAAM refines both the Mg_(2)Si phase and the overall grains,resulting in a homogeneous morphology and improved mechanical properties.The granular Mg_(2)Si phase,characterized by fine particles with a diffused distribution,shows a significant increase in concentration.The acicular Mg_(2)Si phase is distributed along the grain boundaries,and its concentration significantly decreases.The average grain size of the Mg_(2)Si phase is about 9.20μm,about 5 times smaller.The refinement and distribution of the granular Mg_(2)Si phase,as well as the reduction in the amount of needle-like Mg_(2)Si particles,are the key factors for improving the mechanical properties of WAAM Mg-6Si alloy.
基金supported by the National Natural Science Foundation of China(No.12375314)。
文摘Tungsten is considered the most promising plasma-facing material for fusion reactors with exceptional performance.Under certain conditions,activated tungsten dust can be generated through plasma–wall interactions and released into the atmosphere.Activated tungsten migrates downward in the soil after atmospheric deposition.However,effective methods for evaluating the environmental dose of gamma rays emitted by activated tungsten are still lacking.Consequently,a method for evaluating the air-absorbed dose rate of activated tungsten dust was proposed considering soil attenuation.Key parameters including the mass attenuation coefficient and energy absorption build-up factor were determined for the main gamma ray energies of radionuclides within the activated tungsten dust.Additionally,air-absorbed dose rates were calculated by assuming that radioactive sources were located at different soil depths and radii.It was found that a soil depth of 50 cm significantly attenuated the environmental dose by 99.9%,whereas the air-absorbed dose rates within the horizontal distance of 500 cm accounted for 91%of the total dose rate.Therefore,this study underscored the importance of soil attenuation in environmental dose assessments,which must be carefully re-examined for the safety analysis of fusion reactors.
基金supported by the National Natural Science Foundation of China(No.52122407,No.52174285,52404317)the Science and Technology Innovation Program of Hunan Province(No.2022RC3048).
文摘LiNiO_(2)(LNO)is one of the most promising cathode materials for lithium-ion batteries.Tungsten element in enhancing the stability of LNO has been researched extensively.However,the understanding of the specific doping process and existing form of W are still not perfect.This study proposes a lithium-induced grain boundary phase W doping mechanism.The results demonstrate that the introduced W atomsfirst react with the lithium source to generate a Li–W–O phase at the grain boundary of primary particles.With the increase of lithium ratio,W atoms gradually diffuse from the grain boundary phase to the interior layered structure to achieve W doping.The feasibility of grain boundary phase doping is verified byfirst principles calculation.Furthermore,it is found that the Li2WO4 grain boundary phase is an excellent lithium ion conductor,which can protect the cathode surface and improve the rate performance.The doped W can alleviate the harmful H2↔H3 phase transition,thereby inhibiting the generation of microcracks,and improving the electrochemical performance.Consequently,the 0.3 wt%W-doped sample provides a significant improved capacity retention of 88.5%compared with the pristine LNO(80.7%)after 100 cycles at 2.8–4.3 V under 1C.
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDs),which allow atomic-scale manipulation,have supe-rior electrical and optical properties that challenge the limits of traditional bulk semiconductors like silicon^([1,2]).As a repre-sentative TMD and a promising 2D channel material for high-performance,scalable p-type transistors,tungsten diselenide(WSe_(2))has attracted considerable academic and industrial interest for its potential in advanced complementary metal−oxide−semiconductor(CMOS)logic technology and in extending Moore’s Law^([3−7]).
基金funded by the China Postdoctoral Science Foundation(Grant No.2022M721614)the opening project of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology(Grant No.KFJJ23-07M)。
文摘This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.
基金financially supported by the National Natural Science Foundation of China(Nos.52371154,52090043,52175371 and 52271147)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515012158)+1 种基金the Knowledge Innovation Program of Wuhan-Basic Researchthe Fundamental Research Funds for the Central Universities(No.2021GCRC003)。
文摘A new two-step spark plasma sintering(TSS)process with low-temperature pre-sintering and high-temperature final sintering has been successfully applied to prepare the tungsten-particle(Wp)-reinforced bulk metallic glass composites(Wp/BMGCs).Compared to normal spark plasma sintering(NS),the densification rate and relative density of Wp/BMGCs can be improved by selecting TSS with appropriate sintering pressure in the low temperature pre-sintering stage.However,the compressive strength and plastic strain of 30%Wp/BMGCs prepared by TSS are both higher than those of the samples prepared by NS.The TSS process can significantly enhance the compressive strength of 30%Wp/BMGCs by 12%and remarkably increase the plastic strain by 50%,while the trend is completely opposite for 50%Wp/BMGCs.Quasi-in situ experiments and finite element simulations reveal that uneven temperature distribution among particles during low-temperature pre-sintering causes local overheating at contact points between particles,accelerating formation of sintering neck between particles and plastic deformation of Wp.When the volume fraction of Wp is low,TSS can improve the interface bonding between particles by increasing the number of sintering necks.This makes the fracture mode of Wp/BMGCs being predominantly transgranular fracture.However,as the volume fraction of Wp increases,the adverse effects of Wp plastic deformation are becoming more and more prominent.The aggregated Wp tends to form a solid"cage structure"that hinders the bonding between particles at the interface;correspondingly,the fracture behavior of Wp/BMGCs is mainly dominated by intergranular fracture.Additionally,reducing the sintering pressure during the low-temperature pre-sintering stage of TSS has been shown to effectively decrease plastic deformation in Wp,resulting in a higher degree of densification and better mechanical properties.
基金support received from the National Key Research and Development Program of China(2022YFB3705000)the National Natural Science Foundation of China(No.52303394)the Liaoning Provincial Natural Science Foundation(No.2023-BS-015).
文摘The formation and evolution of M_(6)C carbides in high-W superalloy following solution treatment was investigated at different temperatures.Initially,during solid solution treatment,MC and M_(6)C carbides was precipitated in the alloy.As the temperature increased,the morphology of M_(6)C carbides transitioned from granular to needle-like.During the solution treatment at 1255℃,the MC carbides degraded and transformed into M_(6)C carbides,forming a symbiotic relationship between them.Nonetheless,no clear orientation relationship was observed between the two types of carbides.After further increasing the temperature to 1270℃,the precipitation of needle-like M_(6)C carbides in the dendrite arm was confirmed.This was supported by electron probe X-ray micro-analyzer and selected area electron diffraction patterns.Subsequently,a detailed examination of the three-dimensional morphology and orientation relationship of the needle-like phase with the matrix was carried out using focused-ion-beam and transmission electron microscopy techniques.The results indicated that the flat interface of the needle phase exhibited a specific orientation relationship with the matrix.However,in the three-dimensional plane,the interfaces between the needle-like phase and the matrix were not straight.Furthermore,no clear orientation relationship between the non-straight interfaces and the matrix was observed.As the solution temperature increased,the tensile properties at room temperature progressively decreased,while the stress rupture properties peaked at 1260℃,suggesting that the alloy demonstrated its optimal comprehensive performance at this temperature.A subsequent analysis was conducted on the longitudinal section of the fracture using electron backscattered diffraction.The results showed a noticeable concentration of stress at the interface between MC and M_(6)C carbides,which ultimately led to crack initiation at this interface.In addition,as the solid solution temperature increased,the quantity of symbiotic phases also increased.This phenomenon led to the initiation of cracks at multiple locations,which then propagated and interconnected.As a consequence,the tensile properties and stress rupture life of the alloy progressively deteriorated.
基金This study is financially supported by the National Science Fund for Distinguished Young Scholars(No.42025301)Guizhou Provincial 2020 Science and Technology Subsidies(No.GZ2020SIG).
文摘The Xingluokeng deposit is the largest gran-ite-related tungsten deposit within the Wuyi metallogenic belt in South China.The Xingluokeng intrusion primarily consists of porphyritic biotite granite,biotite granite,andfine-grained granite.The deposit is represented by veinlet-disseminated mineralization with K-feldspathization and biotitization,alongside quartz-vein mineralization with gre-isenization and sericitization.This study investigates in-situ analyses of quartz compositions from both the intrusion and hydrothermal veinlets and veins.Trace element correlations indicate that trivalent Al^(3+)and Fe^(3+)replace Si^(4+)within the quartz lattice,with monovalent cations(such as Li^(+),Na^(+),and K^(+))primarily serving as charge compensators.Low Ge/Al ratios(<0.013)of quartz from granites suggest a mag-matic origin.The low Al/Ti and Ge/Ti ratios,accompanied by high Ti contents in quartz,suggest that the porphyritic biotite granite and biotite granite are characterized by rela-tively low levels of differentiation and high crystallization temperatures.In contrast,thefine-grained granite exhibits a higher degree of fractionation,lower crystallization tem-peratures,and a closer association with tungsten miner-alization.Ti contents in quartz from quartz veins indicate Qz-Ⅰformed at temperatures above 400°C,while Qz-Ⅱto Qz-Ⅴformed at temperatures below 350°C.Variations in different generations of quartz,as indicated by Al content and(Al+Fe)/(Li+Na+K)ratio,suggest that Qz-Ⅰprecipi-tated from a less acidicfluid with a stable pH,whereas Qz-Ⅱto Qz-Ⅴoriginated from a more acidicfluid with notable pH variations.Consequently,alkaline alteration and acidic alteration supplied the essential Ca and Fe for the precipita-tion of scheelite and wolframite,respectively,highlighting a critical mechanism in tungsten mineralization at the Xin-gluokeng deposit.
