The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solutio...The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solution were used to regulate the microstructure,mechanical properties,and corrosion properties of B_(4)C/TC4 composite.Results show that with the increase in temperature from 500℃to 800°C,partial lamellarα-Ti in the as-deposited sample is gradually transformed into equiaxedα-Ti,accompanied by the disappearance of basketweave microstructure.At 1100°C,a small portion of TiC phase suffers fusion.This composite exhibits the optimal combination of strength and plasticity after annealing at 500℃for 4 h followed by furnace cooling,which is attributed to the stress release effect and the refined basketweave microstructure.However,this composite shows a decline in corrosion resistance after various heat treatments due to grain coarsening and micro-galvanic corrosion.展开更多
As the demand for high-strength materials at elevated temperatures grows,this study pioneers a novel approach to the high-temperature mechanical properties enhancement of Inconel 718 alloy,achieving this through the c...As the demand for high-strength materials at elevated temperatures grows,this study pioneers a novel approach to the high-temperature mechanical properties enhancement of Inconel 718 alloy,achieving this through the controlled reinforcement with titanium carbide particles(TiCp)via laser powder directed energy deposition(LPDED).Core-shell composite powders with varying TiCp content(1,3,and 5 wt%)were prepared using the surface modification and reinforcement transplantation method.The LPDED-printed TiCp-added specimens,which were crack-free and homogeneous,exhibited a higher density compared to their pristine counterparts.Microstructural variations were observed in the as-built and heat-treated samples,which impacted the mechanical properties at room and high temperatures.Notably,the sample with a 3 wt%TiCp addition exhibited an exceptional yield strength at 800°C,demonstrating a 40%enhancement compared to its wrought Inconel 718 counterpart while also satisfying elongation requirements at room temperature.Through the analysis of the strengthening mechanism and investigation of mechanically tested samples at high temperatures,the strengthening enhancement is mainly induced by interstitial atom clusters near the dislocations and precipitates.This investigation underscores the modification of the microstructural and mechanical characteristics through TiCp control in LPDED,offering insights into the development of high-performance metal matrix composites for high-temperature applications.展开更多
The crack initiation and early propagation are of great significance to the overall fatigue life of material.In order to investigate the anisotropic fracture behavior of laser metal deposited Ti-6Al-4V alloy(LMD Ti64)...The crack initiation and early propagation are of great significance to the overall fatigue life of material.In order to investigate the anisotropic fracture behavior of laser metal deposited Ti-6Al-4V alloy(LMD Ti64)during the early stage,the fourpoint bending fatigue test was carried out on specimens of three different directions,as well as the forged specimens.The results indicate the anisotropic crack initiation and early propagation of LMD Ti64.The direction perpendicular to the deposition direction exhibits a better fatigue resistance than the other two.The crack initiation position and propagation path are dominated by the microstructure in the vicinity of U-notch.LMD Ti64 has a typical small crack effect,and the early crack propagation velocities in three directions are similar.Affected by the slip system of LMD Ti64,secondary cracks frequently occur,which are often found to have an angle of 60°to the main crack.The electron backscatter diffraction analysis indicates that LMD Ti64 has preferred orientations,i.e.,strong 0001//Z texture and 001//Z texture.Their crystallographic orientation will change as the direction of columnarβgrains turns over,resulting in the fatigue anisotropy of LMD Ti64 in crack initiation and early crack propagation process.展开更多
The reaction rate constant is a crucial kinetic parameter that governs the charge and discharge performance of batteries,particularly in high-rate and thick-electrode applications.However,conventional estimation or fi...The reaction rate constant is a crucial kinetic parameter that governs the charge and discharge performance of batteries,particularly in high-rate and thick-electrode applications.However,conventional estimation or fitting methods often overestimate the charge transfer overpotential,leading to substantial errors in reaction rate constant measurements.These inaccuracies hinder the accurate prediction of voltage profiles and overall cell performance.In this study,we propose the characteristic time-decomposed overpotential(CTDO)method,which employs a single-layer particle electrode(SLPE)structure to eliminate interference overpotentials.By leveraging the distribution of relaxation times(DRT),our method effectively isolates the characteristic time of the charge transfer process,enabling a more precise determination of the reaction rate constant.Simulation results indicate that our approach reduces measurement errors to below 2%,closely aligning with theoretical values.Furthermore,experimental validation demonstrates an 80% reduction in error compared to the conventional galvanostatic intermittent titration technique(GITT)method.Overall,this study provides a novel voltage-based approach for determining the reaction rate constant,enhancing the applicability of theoretical analysis in electrode structural design and facilitating rapid battery optimization.展开更多
A novel nitrogenous nickel-based deposited metal was prepared by gas metal arc welding.Subsequently,solid solution treatment as well as solution and aging treatments were conducted on the prepared metal to study the e...A novel nitrogenous nickel-based deposited metal was prepared by gas metal arc welding.Subsequently,solid solution treatment as well as solution and aging treatments were conducted on the prepared metal to study the evolution of microstructure and tensile properties at different states.Results show that the high-temperature tensile strength of the deposited metal exhibits good performance after the addition of W and N.The grain size of the sample is large,and petal-like Laves phase appears at the grain boundaries.After solid solution treatment,the grain size decreases,and the Laves phase disappears.However,both the yield strength and elongation of the deposited metal decrease.The grain size of the samples after solid solution and aging treatment is more uniform,nanoscale M(C,N)phases are precipitated within the crystals,and M_(23)C_(6) phase forms at grain boundaries.The yield strength and ultimate tensile strength of this sample are higher than those of the other samples,but its plasticity is the lowest.The main deformation mechanism is the unit dislocation a/2<110>cutting the precipitation phase.展开更多
The optimization of deposited metal properties through the addition of rare earth elements to welding materials was explored.Utilizing optical microscope,scanning electron microscope,energy dispersive spectroscope,and...The optimization of deposited metal properties through the addition of rare earth elements to welding materials was explored.Utilizing optical microscope,scanning electron microscope,energy dispersive spectroscope,and X-ray diffractometer,combined with software tools like Matlab,Image-Pro Plus,and CHANNEL5,the influence mechanism of rare earth element addition on the strength,toughness,and inclusions of deposited metal in 1000 MPa grade high-strength steel was investigated.The results indicate that the incorporation of rare earth elements enhances the weldability of the welding materials.With the addition of rare earth elements,the tensile strength of the deposited metal increases from 935 MPa to 960 MPa.However,further addition leads to a decrease in tensile strength,while the yield strength continuously increases by 8.5%-17.2%.The addition of appropriate amounts of rare earth elements results in an increase in acicular ferrite and retained austenite content,as well as grain refinement in the deposited metal,leading to 8.5%-24.3% and 15.6%-42.2% enhancement in impact energy at−40℃ and−60℃,respectively.Additionally,the proper addition of rare earth elements modifies the inclusions and generates fine and dispersed composite inclusions that bond better with the matrix,thereby optimizing the properties of the deposited metal through various mechanisms.Adding an appropriate amount of rare earth elements can significantly enhance the properties of the deposited metal in 1000 MPa grade high-strength steel,and improve the match between high strength and toughness,meeting the demands for high-strength steel used in hydropower applications.展开更多
9Cr ferritic/martensitic(9Cr F/M)steels are considered ideal structural materials for various nuclear energy systems.However,δ-ferrite(δ),as a controlled phase,may occur in its welds.Three deposited metals with diff...9Cr ferritic/martensitic(9Cr F/M)steels are considered ideal structural materials for various nuclear energy systems.However,δ-ferrite(δ),as a controlled phase,may occur in its welds.Three deposited metals with different carbon contents(0.04,0.07,and 0.10 wt%)were investigated using experimental and finite element simulation methods.The results showed that the incomplete peritectic reaction,the incompleteδto austenite phase transition,and the segregation of ferrite-stabilized elements led to the residualδ.The amount and morphology ofδsignificantly influence the mechanical properties.After increasing the carbon content,the increase in strength comes mainly from precipitation strengthening and dislocation strengthening,the presence ofδwill reduce the strength.During the impact process,δaffects the absorbed energy for the stable crack growth through its morphology,and M_(23)C_(6)affects the crack formation energy through its quantity.By decreasing the carbon content to a certain extent,the reduction of M_(23)C_(6)content and the generation of large polygonalδcan effectively improve the toughness of 9Cr-steel deposited metals.展开更多
Here we fabricate LA103Z Mg-Li alloy via wire-arc directed energy deposition(WA-DED),and subsequent aging treatment is employed to improve its mechanical property.Results show that a typical dual-phase microstructure ...Here we fabricate LA103Z Mg-Li alloy via wire-arc directed energy deposition(WA-DED),and subsequent aging treatment is employed to improve its mechanical property.Results show that a typical dual-phase microstructure is formed upon WA-DED,consisting of α-Mg,β-Li,AlLi and Li_(2)MgAl,with negligible porosity,and the core-shell Li_(2)MgAl/AlLi composite particles are also generated.After aging treatment,the microstructure is slightly coarsened,together with the precipitation of nano-sized D0_(3)-Mg_(3)Al particles,as well as the dissolution and the mergence of α-Mg phases.Negligible strength and ductility anisotropies are found for the as-deposited alloy.Significant strength increment is achieved via aging treatment,and the ultimate strength increases by~20%(~34 MPa),reaching 200±1 MPa.Both as-deposited and aged alloys show acceptable uniform elongation,with a transgranular fracture mode.Precipitation strengthening enabled by nano-sized D0_(3)-Mg_(3)Al precipitates is primarily responsible for the strength increment mediated by aging treatment.Grain refinement strengthening and solid solution strengthening provide additional contributions to the improved strength.Our work thus offers an applicable additive manufacturing pathway for the efficient and safety-guaranteed fabrication of Mg-Li alloy components with decent mechanical property.展开更多
Morphological control is recognized as a pivotal factor in developing high-performing solution-processed organic photovoltaics(OPVs).The essence of achieving optimal morphology in a sequentially deposited active layer...Morphological control is recognized as a pivotal factor in developing high-performing solution-processed organic photovoltaics(OPVs).The essence of achieving optimal morphology in a sequentially deposited active layer lies in the precise modulation of the micro-morphology of the donor phase,encompassing molecular arrangement,orientation,and crystalline structure.The micro-morphology of the polymer donor layer plays a significant role in determining the vertical composition distribution and the adequacy of the donor/acceptor(D/A)interfaces.In this work,self-solvent vapor annealing(S-SVA)is employed to meticulously engineer the π-πstacking and crystalline domains of polymer donor PM6.This is accomplished by precisely adjusting the evaporation kinetics of the self-solvent and leveraging the swelling effect induced by residual self-solvents,thereby enhancing the self-assembly of PM6 molecules.The resultant improvements inπ-πstacking and coherence length have led to efficient charge transport.These refinements have translated into a power conversion efficiency of 18.2%,accompanied by an open-circuit voltage of 0.886 V,a short-circuit current density of 25.9 mA cm^(-2),and a fill factor of 79.4%.The straightforward yet impactful method not only enhances film crystallinity and device performance but also holds broad application potential.展开更多
The hydro-mechanical responses of vegetated deposited slopes are complex and far from clear.On one hand,the soils in deposited slopes are typically poorly consolidated and widely graded,making them vulnerable to inter...The hydro-mechanical responses of vegetated deposited slopes are complex and far from clear.On one hand,the soils in deposited slopes are typically poorly consolidated and widely graded,making them vulnerable to internal erosion during rainfall infiltration.On the other hand,vegetation plays a significant role in influencing the hydro-mechanical properties of the soil at the slope surface.This paper presents a coupled seepage-erosion model to investigate the rainfall-induced internal erosion process within vegetated deposited slopes and its impact on slope stability.The detailed seepage-erosion coupling processes were simulated for a series of 1D rooted soil columns with varying root distributions,as well as 2D vegetated layered slopes under both light and heavy rainfall conditions.The numerical results reveal that roots can significantly mitigate rainfall-induced internal erosion,even with shallow root lengths.However,their protective effect on the slope increases as the root density in the superficial soil layer increases.Transpiration can rapidly restore matric suction in the shallow soil during rain intervals,slowing the rainfall-induced seepage-erosion process and thereby increasing slope stability.However,in the absence of transpiration,roots may either accelerate or inhibit the seepage-erosion process,depending on the specific rainfall conditions.展开更多
Particle-reinforced aluminum matrix composites(P-AMCs)with properties superior to those of conventional aluminum alloys can be rapidly printed via arc-directed energy deposition(arc-DED),but elemental segregation occu...Particle-reinforced aluminum matrix composites(P-AMCs)with properties superior to those of conventional aluminum alloys can be rapidly printed via arc-directed energy deposition(arc-DED),but elemental segregation occurs in the printed components,and the enhancement of the mechanical properties of the materials is limited.In this study,P-AMC components containing nanoparticles were deposited and strengthened using a customized heat treatment process.A coherent Guinier–Preston(GP)zone and a semicoherentη'metastable phase(MgZn_(2)type)combined with TiC nanoparticles to form a triple reinforcement.The strength of the alloy was enhanced by the synergistic effects of fine-grain strengthening,Orowan dislocation bypassing,and dislocation shearing.The average tensile strength of the sample could reach 581.3±11.7 MPa,which is a 164%performance enhancement over that of conventional particle-reinforced AMC arc-DED components.A tensile strength of 74%was maintained at 200°C,which resulted in superior elongation(9.43%increase).This paper provides new concepts for the development of AMCs with high specific strength and excellent thermal stability.展开更多
The wear behavior of Ni-based single crystal(NBSC)superalloy SRR99 fabricated by laser-directed energy deposition(LDED)is investigated and compared with that of its cast counterpart.While γ'precipitate size in th...The wear behavior of Ni-based single crystal(NBSC)superalloy SRR99 fabricated by laser-directed energy deposition(LDED)is investigated and compared with that of its cast counterpart.While γ'precipitate size in the latter is>400 nm,that in the former is an order of magnitude lower.Dry sliding wear tests reveal that the wear rate and coefficient of friction of the LDED alloy are 75% and 20%lower than that of its cast counterpart,respectively.Detailed transmission electron microscopy investigation of the wear-tested cast alloy indicates that there is orientation change and formation of nanoscale grains only at the top layer of the worn surface,whereas regions below undergo moderate plastic deformation via dislocation slip.In contrast,the sub-surface of the worn LDED alloy has a graded microstructure,with a composite of NiO/γ-Ni on the top,γ'free nano-grains in the middle,and a highly deformed nanoscale layer at the bottom.The improved wear behavior of the LDED alloy is attributed to its higher dislocation density,finerγ'precipitates,and the formation of this graded microstructure.Finally,a detailed description of mechanisms that lead to the formation of this unique graded microstructure is provided.展开更多
We report on the microstructure and the strengthening mechanisms of additively manufactured parts fabricated by directed energy deposition of Ti-6Al-4V(Ti64)powders blended with yttria-stabilized zirconia(YSZ)nanopart...We report on the microstructure and the strengthening mechanisms of additively manufactured parts fabricated by directed energy deposition of Ti-6Al-4V(Ti64)powders blended with yttria-stabilized zirconia(YSZ)nanoparticles.These specimens showed refined microstructures as compared to bare as-deposited Ti64,where theαand columnar priorβgrain sizes decreased with increasing YSZ content.The YSZ nanoparticles decomposed during the deposition process and led to the formation of yttrium oxide and some excess oxygen in the Ti64 matrix.The decrease in the sizes of the priorβgrains could be attributed to the increasing amount of dissolved oxygen and yttrium,which promoted constitutional supercooling.Furthermore,the reduction in the size of theαgrains could be ascribed to a shift of the onset of theβ→α+βtransformation to a higher temperature and shorter time with increasing concentration of dissolved oxygen.Finally,the contributions of the underlying strengthening mechanisms for the as-deposited specimens were quantitatively determined.展开更多
The Mailong gold deposit is located in the eastern section of the East Kunlun orogenic belt and is one of the recently discovered important gold polymetallic deposits in the Qinhai Gouli region.The primary host rocks ...The Mailong gold deposit is located in the eastern section of the East Kunlun orogenic belt and is one of the recently discovered important gold polymetallic deposits in the Qinhai Gouli region.The primary host rocks of the Mailong gold deposit consist of intermediate-acid intrusive rocks from the Varisian and Indosinian periods,as well as the Precambrian Jinshuikou Group,with mineralization controlled by northeast and northwest faults.The alteration of the host rocks is mainly characterized by silicification,sericitization,chloritization,and carbonatization.Based on the cross-cutting relationships of the veins,the hydrothermal mineralization of the gold deposit can be categorized into three stages:the quartz-pyrite stage,the quartzpolymetallic sulfide stage,and the quartz-carbonate stage.Microthermometry of fluid inclusions indicates that the Mailong gold deposit belongs to a low-density(0.73–0.86 g/cm3),medium-temperature(240–340℃),and medium-salinity(4.01–10.74 wt%NaCl)NaCl-CO2-H2O fluid system.The C-H-O isotopic analysis suggests that the mineralizing fluids is derived from magmatic water,with later contributions from atmospheric precipitation.In-situ S isotopic results indicate that the mineralizing materials mainly derive from igneous rocks.A comprehensive analysis concludes that the Mailong gold deposit is a mesothermal hydrothermal vein-type gold deposit controlled by structural factors.展开更多
The fatigue crack growth rate of a novel Ti-6Al-4V-1Mo titanium alloy,which is developed for laser directed energy deposition technique,was investigated before and after cyclic heat treatment(CHT).Changes in microstru...The fatigue crack growth rate of a novel Ti-6Al-4V-1Mo titanium alloy,which is developed for laser directed energy deposition technique,was investigated before and after cyclic heat treatment(CHT).Changes in microstructure,fracture surfaces,and crack growth paths were analyzed before and after CHT.Results indicate that in the stable crack growth region,the growth rates for the as-deposited and cyclic heat-treated specimens follow the relationships da/dN=1.8651×10^(−8)(ΔK)^(3.2271)and da/dN=1.4112×10^(−8)(ΔK)^(3.1125),respectively.Compared with that at the as-deposited state,the microstructure after CHT is transformed from a uniform basket-weave microstructure to a dual-phase microstructure consisting of near-sphericalαandβ-transformed matrix phases.The cyclic process also disrupts the continuity of the grain boundaryα(αGB)at the primaryβ-phase grain boundary.The coarsening of primaryαand the disruption ofαGB continuity are the primary factors to release stress concentration and promote crack deflection,thereby decreasing the fatigue crack growth rate.Additionally,the increased occurrence of crack branching,secondary cracking,and crack bridging in cyclic heat-treated specimens further reduces the crack driving force and slows the fatigue crack growth rate.展开更多
The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viabili...The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viability.Thermodynamic phase diagrams were developed to intuitively represent carbon deposition and carburization preferences in CH4-CO-H_(2) ternary atmospheres.High carbon potential and low oxygen potential significantly enhance carbon deposition and carburization.Increasing temperature from 500 to 1000℃ shifts the dominant reactions from CO-based to CH_(4)-based,increasing maximum carbon deposition from 0.55 to 0.80 mol and carburization from 0.25 to 0.80 mol per mole of reducing gas.Increasing pressure suppresses CH4-based reactions while promoting CO-based reactions,reducing maximum carbon deposition from 0.8 to~0.7 mol and increasing maximum carburization from 0.80 to 0.85 mol per mole of reducing gas.Equilibrium phase diagrams for various carbides were also developed,revealing preferences for Fe_(3)C_(2),Fe_(7)C_(3),Fe_(5)C_(2),and Fe_(3)C as the Fe/C ratio increases.Higher temperatures and CH_(4) concentrations favor the formation of carbides with higher carbon content.Carburization preferences under typical Energiron ZR and Midrex atmospheres were highlighted,and the higher carbon content in direct reduction iron produced by the Energiron ZR process was thermodynamically confirmed.展开更多
Strontianite-rich carbonatite,containing over 30 vol%carbonate minerals predominantly composed of strontianite(SrCO3),is identified in the Zhengjialiangzi ore segment of the Muluozhai rare earth element(REE)deposit,we...Strontianite-rich carbonatite,containing over 30 vol%carbonate minerals predominantly composed of strontianite(SrCO3),is identified in the Zhengjialiangzi ore segment of the Muluozhai rare earth element(REE)deposit,western Sichuan Province,China.It exhibits a unique mineral assemblage dominated by strontianite,fluorite,bastnäsite,barite,calcite and dolomite,distinguishing it from conventional calcio-,magnesio-,ferro-,or natro-carbonatites.The rock shows extreme enrichment in REEs(ΣREE=47335-64367 ppm),with strong LREE/HREE fractionation[(La/Yb)N=1151-2119]and notably high concentrations of high-value critical REEs(e.g.,Pr,Nd,Tb,Dy),5-10 times greater than those in local calcite-dominated carbonatites.Trace element patterns indicate significant enrichment in REEs,Sr,and Ba,along with depletion in high-field-strength elements(HFSEs;e.g.,Nb,Ta,Zr,Hf).In-situ Sr isotopes of strontianite[(^(87)Sr/^(86)Sr)i=0.706190-0.707305]indicate an enriched mantle source(EMI-EMII).Sr enrichment is attributed to initial mantle source enrichment and extensive fractional crystallization,possibly accompanied by minor wall-rock assimilation.We propose that the strontianite-rich carbonatite formed from a highly evolved,Sr-and REEs-rich carbonatitic magma that intruded into shallow structural breccias,followed by rapid cooling.Its formation is associated with a continuous melt-fluid evolutionary process that is characteristic of carbonatitic systems.展开更多
Pulse tube cryocoolers are widely employed in cryogenic systems,where gas contamination has become a critical factor limiting both performance and service life.To further investigate the condensation behavior of conta...Pulse tube cryocoolers are widely employed in cryogenic systems,where gas contamination has become a critical factor limiting both performance and service life.To further investigate the condensation behavior of contaminants,this study develops a two-dimensional axisymmetric model of a linear-type cryocooler to simulate the transport and deposition processes of trace CO_(2),evaluating the impact of contamination on system pressure drop under various operating conditions.Results indicate that CO_(2)diffusion is primarily driven by concentration gradients.The CO_(2)deposition rate increases markedly at low temperatures and high concentrations,with over 90%of deposition occurring in the cold-end heat exchanger.Under different concentration distributions,dry ice predominantly accumulates in the cold-end heat exchanger;however,notable differences emerge in the pulse tube.In the uniform distribution case,CO_(2)tends to deposit along the inner wall of the pulse tube,whereas in the gradual release scenario,deposition mainly occurs on the cold-end flow straightening mesh screen.Dry ice deposition significantly increases the pressure drop across the system and decreases the pressure wave amplitude,resulting in a degradation of cooling capacity.This study lays a foundation for further investigation into the thermal properties of contaminant layers and provides theoretical guidance for optimizing cold-end components to improve contamination resilience.展开更多
Epithermal deposits are characterized by complex low-temperature hydrothermal alterations, but the links between mineralization and superimposed alteration are obscure and require further elucidation. This study emplo...Epithermal deposits are characterized by complex low-temperature hydrothermal alterations, but the links between mineralization and superimposed alteration are obscure and require further elucidation. This study employs shortwave infrared(SWIR) spectral scalars for alteration mineral mapping and three-dimensional modeling of the Ulan Uzhur Ag polymetallic deposit, a newly discovered epithermal deposit in the Qimantagh. Alteration zoning transitions from illitemuscovite-carbonate-pyrite in the core(Zone Ⅰ), through muscovite ± illite-kaolinite-chlorite-carbonate(Zone Ⅱ), to muscovite-chlorite-biotite(Zone Ⅲ) at the periphery. The Zone Ⅰ with mineralization features long-wavelength white mica(wAlOH > 2207 nm) with a high Illite Crystallinity(IC)(mean > 2.0), suggesting a relatively high-temperature environment conducive to mineralization. Petrographic analyses with fluid inclusion and IC curve characteristics suggests that fluid boiling may be a pivotal mechanism for mineral precipitation. Furthermore, surface mapping and deep threedimensional modeling of spectral characteristics reveal a correlation between long-wavelength white mica, high IC and mineralization zones. These findings indicate that SWIR spectroscopy reveal the evolution of fluids and provide valuable guidance for future exploration efforts.展开更多
The Mianhuakeng uranium deposit,characterized by uranium-rich granite,serves as a key site for research into crustal radioactive heating.Based on 45 rock samples,this study reviews that the host granite in the Mianhua...The Mianhuakeng uranium deposit,characterized by uranium-rich granite,serves as a key site for research into crustal radioactive heating.Based on 45 rock samples,this study reviews that the host granite in the Mianhuakeng uranium deposit has a high radioactive heat production rate(avg.5.50μW/m³)and a low Th/U ratio(avg.2.62).Uranium-rich granite and its alteration zone within the upper crust(0-5 km depth)contribute about 45%of the total radioactive heat production,wich is crucial for controlling geothermal resource distribution.For uranium-thermal at tectonic plate margins,a symbiotic geological model was proposed:Firstly,subduction of the Pacific Plate caused upwelling of the asthenosphere,generating a high heat-flow background.Secondly,heat transfer is enhanced by major faults such as the Youdong and Mianhuakeng faults.Subsequently,uranium was mobilized,transported,and enriched within the granite through deep siliceous hydrothermal activity and associated alteration.Ultimately,the uranium enrichment in granite leads to increased radioactive heat production,resulting in local thermal anomalies.This model provides a theoretical support for exploring and developing uranium-thermal symbiotic resources in South China.展开更多
基金Tianjin Municipal Natural Science Foundation(23JCYBJC00040)National Natural Science Foundation of China(52175369)。
文摘The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solution were used to regulate the microstructure,mechanical properties,and corrosion properties of B_(4)C/TC4 composite.Results show that with the increase in temperature from 500℃to 800°C,partial lamellarα-Ti in the as-deposited sample is gradually transformed into equiaxedα-Ti,accompanied by the disappearance of basketweave microstructure.At 1100°C,a small portion of TiC phase suffers fusion.This composite exhibits the optimal combination of strength and plasticity after annealing at 500℃for 4 h followed by furnace cooling,which is attributed to the stress release effect and the refined basketweave microstructure.However,this composite shows a decline in corrosion resistance after various heat treatments due to grain coarsening and micro-galvanic corrosion.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(No.NRF-2022R1A5A1030054)the Ministry of Science and ICT(No.RS-2024-00402378).
文摘As the demand for high-strength materials at elevated temperatures grows,this study pioneers a novel approach to the high-temperature mechanical properties enhancement of Inconel 718 alloy,achieving this through the controlled reinforcement with titanium carbide particles(TiCp)via laser powder directed energy deposition(LPDED).Core-shell composite powders with varying TiCp content(1,3,and 5 wt%)were prepared using the surface modification and reinforcement transplantation method.The LPDED-printed TiCp-added specimens,which were crack-free and homogeneous,exhibited a higher density compared to their pristine counterparts.Microstructural variations were observed in the as-built and heat-treated samples,which impacted the mechanical properties at room and high temperatures.Notably,the sample with a 3 wt%TiCp addition exhibited an exceptional yield strength at 800°C,demonstrating a 40%enhancement compared to its wrought Inconel 718 counterpart while also satisfying elongation requirements at room temperature.Through the analysis of the strengthening mechanism and investigation of mechanically tested samples at high temperatures,the strengthening enhancement is mainly induced by interstitial atom clusters near the dislocations and precipitates.This investigation underscores the modification of the microstructural and mechanical characteristics through TiCp control in LPDED,offering insights into the development of high-performance metal matrix composites for high-temperature applications.
基金National Natural Science Foundation of China(12172292,12072287)。
文摘The crack initiation and early propagation are of great significance to the overall fatigue life of material.In order to investigate the anisotropic fracture behavior of laser metal deposited Ti-6Al-4V alloy(LMD Ti64)during the early stage,the fourpoint bending fatigue test was carried out on specimens of three different directions,as well as the forged specimens.The results indicate the anisotropic crack initiation and early propagation of LMD Ti64.The direction perpendicular to the deposition direction exhibits a better fatigue resistance than the other two.The crack initiation position and propagation path are dominated by the microstructure in the vicinity of U-notch.LMD Ti64 has a typical small crack effect,and the early crack propagation velocities in three directions are similar.Affected by the slip system of LMD Ti64,secondary cracks frequently occur,which are often found to have an angle of 60°to the main crack.The electron backscatter diffraction analysis indicates that LMD Ti64 has preferred orientations,i.e.,strong 0001//Z texture and 001//Z texture.Their crystallographic orientation will change as the direction of columnarβgrains turns over,resulting in the fatigue anisotropy of LMD Ti64 in crack initiation and early crack propagation process.
基金supported by the National Key R&D Program of China 2022YFB2404300the National Natural Science Foundation of China U22B2069the China Postdoctoral Science Foundation 2024M761006。
文摘The reaction rate constant is a crucial kinetic parameter that governs the charge and discharge performance of batteries,particularly in high-rate and thick-electrode applications.However,conventional estimation or fitting methods often overestimate the charge transfer overpotential,leading to substantial errors in reaction rate constant measurements.These inaccuracies hinder the accurate prediction of voltage profiles and overall cell performance.In this study,we propose the characteristic time-decomposed overpotential(CTDO)method,which employs a single-layer particle electrode(SLPE)structure to eliminate interference overpotentials.By leveraging the distribution of relaxation times(DRT),our method effectively isolates the characteristic time of the charge transfer process,enabling a more precise determination of the reaction rate constant.Simulation results indicate that our approach reduces measurement errors to below 2%,closely aligning with theoretical values.Furthermore,experimental validation demonstrates an 80% reduction in error compared to the conventional galvanostatic intermittent titration technique(GITT)method.Overall,this study provides a novel voltage-based approach for determining the reaction rate constant,enhancing the applicability of theoretical analysis in electrode structural design and facilitating rapid battery optimization.
文摘A novel nitrogenous nickel-based deposited metal was prepared by gas metal arc welding.Subsequently,solid solution treatment as well as solution and aging treatments were conducted on the prepared metal to study the evolution of microstructure and tensile properties at different states.Results show that the high-temperature tensile strength of the deposited metal exhibits good performance after the addition of W and N.The grain size of the sample is large,and petal-like Laves phase appears at the grain boundaries.After solid solution treatment,the grain size decreases,and the Laves phase disappears.However,both the yield strength and elongation of the deposited metal decrease.The grain size of the samples after solid solution and aging treatment is more uniform,nanoscale M(C,N)phases are precipitated within the crystals,and M_(23)C_(6) phase forms at grain boundaries.The yield strength and ultimate tensile strength of this sample are higher than those of the other samples,but its plasticity is the lowest.The main deformation mechanism is the unit dislocation a/2<110>cutting the precipitation phase.
基金Provincial Key Research and Development Plan of Heilongjiang(2022ZX04A01)。
文摘The optimization of deposited metal properties through the addition of rare earth elements to welding materials was explored.Utilizing optical microscope,scanning electron microscope,energy dispersive spectroscope,and X-ray diffractometer,combined with software tools like Matlab,Image-Pro Plus,and CHANNEL5,the influence mechanism of rare earth element addition on the strength,toughness,and inclusions of deposited metal in 1000 MPa grade high-strength steel was investigated.The results indicate that the incorporation of rare earth elements enhances the weldability of the welding materials.With the addition of rare earth elements,the tensile strength of the deposited metal increases from 935 MPa to 960 MPa.However,further addition leads to a decrease in tensile strength,while the yield strength continuously increases by 8.5%-17.2%.The addition of appropriate amounts of rare earth elements results in an increase in acicular ferrite and retained austenite content,as well as grain refinement in the deposited metal,leading to 8.5%-24.3% and 15.6%-42.2% enhancement in impact energy at−40℃ and−60℃,respectively.Additionally,the proper addition of rare earth elements modifies the inclusions and generates fine and dispersed composite inclusions that bond better with the matrix,thereby optimizing the properties of the deposited metal through various mechanisms.Adding an appropriate amount of rare earth elements can significantly enhance the properties of the deposited metal in 1000 MPa grade high-strength steel,and improve the match between high strength and toughness,meeting the demands for high-strength steel used in hydropower applications.
基金supported by the LingChuang Research Project of China National Nuclear Corporation,China Institute of Atomic Energy(E141L803J1)the Natural Science Foundation of Heilongjiang Province(No.TD2021E006).
文摘9Cr ferritic/martensitic(9Cr F/M)steels are considered ideal structural materials for various nuclear energy systems.However,δ-ferrite(δ),as a controlled phase,may occur in its welds.Three deposited metals with different carbon contents(0.04,0.07,and 0.10 wt%)were investigated using experimental and finite element simulation methods.The results showed that the incomplete peritectic reaction,the incompleteδto austenite phase transition,and the segregation of ferrite-stabilized elements led to the residualδ.The amount and morphology ofδsignificantly influence the mechanical properties.After increasing the carbon content,the increase in strength comes mainly from precipitation strengthening and dislocation strengthening,the presence ofδwill reduce the strength.During the impact process,δaffects the absorbed energy for the stable crack growth through its morphology,and M_(23)C_(6)affects the crack formation energy through its quantity.By decreasing the carbon content to a certain extent,the reduction of M_(23)C_(6)content and the generation of large polygonalδcan effectively improve the toughness of 9Cr-steel deposited metals.
基金supported by the National Natural Science Foundation of China(52475320).
文摘Here we fabricate LA103Z Mg-Li alloy via wire-arc directed energy deposition(WA-DED),and subsequent aging treatment is employed to improve its mechanical property.Results show that a typical dual-phase microstructure is formed upon WA-DED,consisting of α-Mg,β-Li,AlLi and Li_(2)MgAl,with negligible porosity,and the core-shell Li_(2)MgAl/AlLi composite particles are also generated.After aging treatment,the microstructure is slightly coarsened,together with the precipitation of nano-sized D0_(3)-Mg_(3)Al particles,as well as the dissolution and the mergence of α-Mg phases.Negligible strength and ductility anisotropies are found for the as-deposited alloy.Significant strength increment is achieved via aging treatment,and the ultimate strength increases by~20%(~34 MPa),reaching 200±1 MPa.Both as-deposited and aged alloys show acceptable uniform elongation,with a transgranular fracture mode.Precipitation strengthening enabled by nano-sized D0_(3)-Mg_(3)Al precipitates is primarily responsible for the strength increment mediated by aging treatment.Grain refinement strengthening and solid solution strengthening provide additional contributions to the improved strength.Our work thus offers an applicable additive manufacturing pathway for the efficient and safety-guaranteed fabrication of Mg-Li alloy components with decent mechanical property.
基金financially supported by the Sichuan Science and Technology Program(2023NSFSC0990,2023YFH0085,2023YFH0086,and 2023YFH0087)the State Key Laboratory of Polymer Materials Engineering(sklpme2022-3-02,sklpme20232-11,and sklpme2024-2-15)。
文摘Morphological control is recognized as a pivotal factor in developing high-performing solution-processed organic photovoltaics(OPVs).The essence of achieving optimal morphology in a sequentially deposited active layer lies in the precise modulation of the micro-morphology of the donor phase,encompassing molecular arrangement,orientation,and crystalline structure.The micro-morphology of the polymer donor layer plays a significant role in determining the vertical composition distribution and the adequacy of the donor/acceptor(D/A)interfaces.In this work,self-solvent vapor annealing(S-SVA)is employed to meticulously engineer the π-πstacking and crystalline domains of polymer donor PM6.This is accomplished by precisely adjusting the evaporation kinetics of the self-solvent and leveraging the swelling effect induced by residual self-solvents,thereby enhancing the self-assembly of PM6 molecules.The resultant improvements inπ-πstacking and coherence length have led to efficient charge transport.These refinements have translated into a power conversion efficiency of 18.2%,accompanied by an open-circuit voltage of 0.886 V,a short-circuit current density of 25.9 mA cm^(-2),and a fill factor of 79.4%.The straightforward yet impactful method not only enhances film crystallinity and device performance but also holds broad application potential.
基金supported by National Natural Science Foundation of China(Grant No.42372330)Science and Technology Research Program of Institute of Mountain Hazards and Environment,Chinese Academy of Sciences(Grant No.IMHE-CXTD-01-IMHE-ZYTS-12)Sichuan Science and Technology Program(Grant No.2024NSFSC0102).
文摘The hydro-mechanical responses of vegetated deposited slopes are complex and far from clear.On one hand,the soils in deposited slopes are typically poorly consolidated and widely graded,making them vulnerable to internal erosion during rainfall infiltration.On the other hand,vegetation plays a significant role in influencing the hydro-mechanical properties of the soil at the slope surface.This paper presents a coupled seepage-erosion model to investigate the rainfall-induced internal erosion process within vegetated deposited slopes and its impact on slope stability.The detailed seepage-erosion coupling processes were simulated for a series of 1D rooted soil columns with varying root distributions,as well as 2D vegetated layered slopes under both light and heavy rainfall conditions.The numerical results reveal that roots can significantly mitigate rainfall-induced internal erosion,even with shallow root lengths.However,their protective effect on the slope increases as the root density in the superficial soil layer increases.Transpiration can rapidly restore matric suction in the shallow soil during rain intervals,slowing the rainfall-induced seepage-erosion process and thereby increasing slope stability.However,in the absence of transpiration,roots may either accelerate or inhibit the seepage-erosion process,depending on the specific rainfall conditions.
基金supported by National Natural Science Foundation of China(Grant No.52305362).
文摘Particle-reinforced aluminum matrix composites(P-AMCs)with properties superior to those of conventional aluminum alloys can be rapidly printed via arc-directed energy deposition(arc-DED),but elemental segregation occurs in the printed components,and the enhancement of the mechanical properties of the materials is limited.In this study,P-AMC components containing nanoparticles were deposited and strengthened using a customized heat treatment process.A coherent Guinier–Preston(GP)zone and a semicoherentη'metastable phase(MgZn_(2)type)combined with TiC nanoparticles to form a triple reinforcement.The strength of the alloy was enhanced by the synergistic effects of fine-grain strengthening,Orowan dislocation bypassing,and dislocation shearing.The average tensile strength of the sample could reach 581.3±11.7 MPa,which is a 164%performance enhancement over that of conventional particle-reinforced AMC arc-DED components.A tensile strength of 74%was maintained at 200°C,which resulted in superior elongation(9.43%increase).This paper provides new concepts for the development of AMCs with high specific strength and excellent thermal stability.
基金supported by the National Key R&D Program of China(Grant Nos.2023YFB3712002 and 2021YFB3702503)the National Natural Science Foundation of China(Grant Nos.51927801 and U2032205)the National Science and Technology Major Project(Grant Nos.Y2019-VII-0011-0151 and 2019-VII-0019-0161)。
文摘The wear behavior of Ni-based single crystal(NBSC)superalloy SRR99 fabricated by laser-directed energy deposition(LDED)is investigated and compared with that of its cast counterpart.While γ'precipitate size in the latter is>400 nm,that in the former is an order of magnitude lower.Dry sliding wear tests reveal that the wear rate and coefficient of friction of the LDED alloy are 75% and 20%lower than that of its cast counterpart,respectively.Detailed transmission electron microscopy investigation of the wear-tested cast alloy indicates that there is orientation change and formation of nanoscale grains only at the top layer of the worn surface,whereas regions below undergo moderate plastic deformation via dislocation slip.In contrast,the sub-surface of the worn LDED alloy has a graded microstructure,with a composite of NiO/γ-Ni on the top,γ'free nano-grains in the middle,and a highly deformed nanoscale layer at the bottom.The improved wear behavior of the LDED alloy is attributed to its higher dislocation density,finerγ'precipitates,and the formation of this graded microstructure.Finally,a detailed description of mechanisms that lead to the formation of this unique graded microstructure is provided.
基金financially supported by the Ministry of Trade,Industry&Energy(MOTIE),Korea Institute for Advancement of Technology(KIAT)[grant number-N0002609]the National Research Foundation(NRF)of Korea[grant number 2020R1A2C2008416]。
文摘We report on the microstructure and the strengthening mechanisms of additively manufactured parts fabricated by directed energy deposition of Ti-6Al-4V(Ti64)powders blended with yttria-stabilized zirconia(YSZ)nanoparticles.These specimens showed refined microstructures as compared to bare as-deposited Ti64,where theαand columnar priorβgrain sizes decreased with increasing YSZ content.The YSZ nanoparticles decomposed during the deposition process and led to the formation of yttrium oxide and some excess oxygen in the Ti64 matrix.The decrease in the sizes of the priorβgrains could be attributed to the increasing amount of dissolved oxygen and yttrium,which promoted constitutional supercooling.Furthermore,the reduction in the size of theαgrains could be ascribed to a shift of the onset of theβ→α+βtransformation to a higher temperature and shorter time with increasing concentration of dissolved oxygen.Finally,the contributions of the underlying strengthening mechanisms for the as-deposited specimens were quantitatively determined.
基金Supported by Qinghai Provincial Geological Exploration Special Fund Project(No.2023085029KY004).
文摘The Mailong gold deposit is located in the eastern section of the East Kunlun orogenic belt and is one of the recently discovered important gold polymetallic deposits in the Qinhai Gouli region.The primary host rocks of the Mailong gold deposit consist of intermediate-acid intrusive rocks from the Varisian and Indosinian periods,as well as the Precambrian Jinshuikou Group,with mineralization controlled by northeast and northwest faults.The alteration of the host rocks is mainly characterized by silicification,sericitization,chloritization,and carbonatization.Based on the cross-cutting relationships of the veins,the hydrothermal mineralization of the gold deposit can be categorized into three stages:the quartz-pyrite stage,the quartzpolymetallic sulfide stage,and the quartz-carbonate stage.Microthermometry of fluid inclusions indicates that the Mailong gold deposit belongs to a low-density(0.73–0.86 g/cm3),medium-temperature(240–340℃),and medium-salinity(4.01–10.74 wt%NaCl)NaCl-CO2-H2O fluid system.The C-H-O isotopic analysis suggests that the mineralizing fluids is derived from magmatic water,with later contributions from atmospheric precipitation.In-situ S isotopic results indicate that the mineralizing materials mainly derive from igneous rocks.A comprehensive analysis concludes that the Mailong gold deposit is a mesothermal hydrothermal vein-type gold deposit controlled by structural factors.
基金National Key Research and Development Program of China(2024YFB4610803)。
文摘The fatigue crack growth rate of a novel Ti-6Al-4V-1Mo titanium alloy,which is developed for laser directed energy deposition technique,was investigated before and after cyclic heat treatment(CHT).Changes in microstructure,fracture surfaces,and crack growth paths were analyzed before and after CHT.Results indicate that in the stable crack growth region,the growth rates for the as-deposited and cyclic heat-treated specimens follow the relationships da/dN=1.8651×10^(−8)(ΔK)^(3.2271)and da/dN=1.4112×10^(−8)(ΔK)^(3.1125),respectively.Compared with that at the as-deposited state,the microstructure after CHT is transformed from a uniform basket-weave microstructure to a dual-phase microstructure consisting of near-sphericalαandβ-transformed matrix phases.The cyclic process also disrupts the continuity of the grain boundaryα(αGB)at the primaryβ-phase grain boundary.The coarsening of primaryαand the disruption ofαGB continuity are the primary factors to release stress concentration and promote crack deflection,thereby decreasing the fatigue crack growth rate.Additionally,the increased occurrence of crack branching,secondary cracking,and crack bridging in cyclic heat-treated specimens further reduces the crack driving force and slows the fatigue crack growth rate.
基金the financial support from the National Key R&D Program of China(No.2024YFC2910800)National Natural Science Foundation of China(52404336)+6 种基金China Postdoctoral Science Foundation(2024M750176)Postdoctoral Fellowship Program of CPSF(GZC20240109)the Young Elite Scientist Sponsorship Program by CAST(YESS20210090)Beijing Natural Science Foundation(J210017)the Project of SKLAM(No.KF24-14)China Baowu Low Carbon Metallurgical Technology Innovation Fund under Grant No.20210901Anhui Major Industrial Innovation Program under Contract No.AHZDCYCX-LSDT2023-01.
文摘The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viability.Thermodynamic phase diagrams were developed to intuitively represent carbon deposition and carburization preferences in CH4-CO-H_(2) ternary atmospheres.High carbon potential and low oxygen potential significantly enhance carbon deposition and carburization.Increasing temperature from 500 to 1000℃ shifts the dominant reactions from CO-based to CH_(4)-based,increasing maximum carbon deposition from 0.55 to 0.80 mol and carburization from 0.25 to 0.80 mol per mole of reducing gas.Increasing pressure suppresses CH4-based reactions while promoting CO-based reactions,reducing maximum carbon deposition from 0.8 to~0.7 mol and increasing maximum carburization from 0.80 to 0.85 mol per mole of reducing gas.Equilibrium phase diagrams for various carbides were also developed,revealing preferences for Fe_(3)C_(2),Fe_(7)C_(3),Fe_(5)C_(2),and Fe_(3)C as the Fe/C ratio increases.Higher temperatures and CH_(4) concentrations favor the formation of carbides with higher carbon content.Carburization preferences under typical Energiron ZR and Midrex atmospheres were highlighted,and the higher carbon content in direct reduction iron produced by the Energiron ZR process was thermodynamically confirmed.
基金the National Natural Science Foundation of China(Grant No.42203073 and 41472072)Basic Scientific Research Fund of the Institute of Geology,CAGS(Grant No.J2317)Sichuan Science and Technology Program(Grant No.2023NSFSC0272).
文摘Strontianite-rich carbonatite,containing over 30 vol%carbonate minerals predominantly composed of strontianite(SrCO3),is identified in the Zhengjialiangzi ore segment of the Muluozhai rare earth element(REE)deposit,western Sichuan Province,China.It exhibits a unique mineral assemblage dominated by strontianite,fluorite,bastnäsite,barite,calcite and dolomite,distinguishing it from conventional calcio-,magnesio-,ferro-,or natro-carbonatites.The rock shows extreme enrichment in REEs(ΣREE=47335-64367 ppm),with strong LREE/HREE fractionation[(La/Yb)N=1151-2119]and notably high concentrations of high-value critical REEs(e.g.,Pr,Nd,Tb,Dy),5-10 times greater than those in local calcite-dominated carbonatites.Trace element patterns indicate significant enrichment in REEs,Sr,and Ba,along with depletion in high-field-strength elements(HFSEs;e.g.,Nb,Ta,Zr,Hf).In-situ Sr isotopes of strontianite[(^(87)Sr/^(86)Sr)i=0.706190-0.707305]indicate an enriched mantle source(EMI-EMII).Sr enrichment is attributed to initial mantle source enrichment and extensive fractional crystallization,possibly accompanied by minor wall-rock assimilation.We propose that the strontianite-rich carbonatite formed from a highly evolved,Sr-and REEs-rich carbonatitic magma that intruded into shallow structural breccias,followed by rapid cooling.Its formation is associated with a continuous melt-fluid evolutionary process that is characteristic of carbonatitic systems.
基金supported by the National Natural Science Foundation of China(No.52376012)the Aeronautical Science Foundation of China(20230024047001).
文摘Pulse tube cryocoolers are widely employed in cryogenic systems,where gas contamination has become a critical factor limiting both performance and service life.To further investigate the condensation behavior of contaminants,this study develops a two-dimensional axisymmetric model of a linear-type cryocooler to simulate the transport and deposition processes of trace CO_(2),evaluating the impact of contamination on system pressure drop under various operating conditions.Results indicate that CO_(2)diffusion is primarily driven by concentration gradients.The CO_(2)deposition rate increases markedly at low temperatures and high concentrations,with over 90%of deposition occurring in the cold-end heat exchanger.Under different concentration distributions,dry ice predominantly accumulates in the cold-end heat exchanger;however,notable differences emerge in the pulse tube.In the uniform distribution case,CO_(2)tends to deposit along the inner wall of the pulse tube,whereas in the gradual release scenario,deposition mainly occurs on the cold-end flow straightening mesh screen.Dry ice deposition significantly increases the pressure drop across the system and decreases the pressure wave amplitude,resulting in a degradation of cooling capacity.This study lays a foundation for further investigation into the thermal properties of contaminant layers and provides theoretical guidance for optimizing cold-end components to improve contamination resilience.
基金supported by the Natural Science Foundation of China(Grant No.42372346,41802080,42030809,41873043).
文摘Epithermal deposits are characterized by complex low-temperature hydrothermal alterations, but the links between mineralization and superimposed alteration are obscure and require further elucidation. This study employs shortwave infrared(SWIR) spectral scalars for alteration mineral mapping and three-dimensional modeling of the Ulan Uzhur Ag polymetallic deposit, a newly discovered epithermal deposit in the Qimantagh. Alteration zoning transitions from illitemuscovite-carbonate-pyrite in the core(Zone Ⅰ), through muscovite ± illite-kaolinite-chlorite-carbonate(Zone Ⅱ), to muscovite-chlorite-biotite(Zone Ⅲ) at the periphery. The Zone Ⅰ with mineralization features long-wavelength white mica(wAlOH > 2207 nm) with a high Illite Crystallinity(IC)(mean > 2.0), suggesting a relatively high-temperature environment conducive to mineralization. Petrographic analyses with fluid inclusion and IC curve characteristics suggests that fluid boiling may be a pivotal mechanism for mineral precipitation. Furthermore, surface mapping and deep threedimensional modeling of spectral characteristics reveal a correlation between long-wavelength white mica, high IC and mineralization zones. These findings indicate that SWIR spectroscopy reveal the evolution of fluids and provide valuable guidance for future exploration efforts.
基金supported by the National Natural Science Foundation of China(41902310,42372348,42372286)Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project(2024ZD1003607)+2 种基金China Geological Survey Projects(DD20230700802,DD20221819)the Basic Research Fund of the Chinese Academy of Geological Sciences(JKYQN202306)Key Research and Development Program of Shanxi Province,China(202102090301009).
文摘The Mianhuakeng uranium deposit,characterized by uranium-rich granite,serves as a key site for research into crustal radioactive heating.Based on 45 rock samples,this study reviews that the host granite in the Mianhuakeng uranium deposit has a high radioactive heat production rate(avg.5.50μW/m³)and a low Th/U ratio(avg.2.62).Uranium-rich granite and its alteration zone within the upper crust(0-5 km depth)contribute about 45%of the total radioactive heat production,wich is crucial for controlling geothermal resource distribution.For uranium-thermal at tectonic plate margins,a symbiotic geological model was proposed:Firstly,subduction of the Pacific Plate caused upwelling of the asthenosphere,generating a high heat-flow background.Secondly,heat transfer is enhanced by major faults such as the Youdong and Mianhuakeng faults.Subsequently,uranium was mobilized,transported,and enriched within the granite through deep siliceous hydrothermal activity and associated alteration.Ultimately,the uranium enrichment in granite leads to increased radioactive heat production,resulting in local thermal anomalies.This model provides a theoretical support for exploring and developing uranium-thermal symbiotic resources in South China.
