A cluster of serpentinite bodies has been recognized tectonically emplaced within the greenschist-amphibolite-facies metamorphic terrane in Hong'an,western Dabie orogen,central China.Two types of serpentinites are...A cluster of serpentinite bodies has been recognized tectonically emplaced within the greenschist-amphibolite-facies metamorphic terrane in Hong'an,western Dabie orogen,central China.Two types of serpentinites are identified on the basis of integrated petrographic,mineralogical and geochemical study.The first type,represented by Yinshanzhai serpentinite complex(Group 1)comprises heterogeneous lithology as a massive serpentinite matrix“intruded”by antigoriteenriched serpentinite lenses.They are both pseudomorphic textured with different mineral assemblages indicating an increasing temperature-pressure condition.Serpentinite matrix(Group 1a)is chemically characterized by high MgO/SiO_(2)and low Al_(2)O_(3)/SiO_(2),Ti and Ca contents,suggesting a depleted mantle wedge origin.The coexistence of compositionally-heterogeneous chromite with highCr^(#)(0.78-0.96)and intermediate-Cr^(#)(0.59-0.70)pristine cores indicates extensive mantle melting.Meanwhile,extremely high Fo olivine relicts(96-97)with considerably higher MnO and lower NiO contents than mantle olivine indicate that they are metamorphic products from serpentine decomposition.Accordingly,we propose that Yinshanzhai serpentinite complex experienced two distinct episodes of hydration.The serpentinite lenses(Group 1b)show higher SiO_(2)and lower MgO concentrations.Nevertheless,the trace elements of groups 1a and 1b are consistent:U-shaped REE patterns,positive Eu anomalies and enrichment of LILE(i.e.,Cs,U)are all identified as forearc properties.They are affected by reducing slab-derived fluids in forearc mantle,with f_(O2)of 1 to 2 logarithmic units below f_(O2)of fayalite-magnetite-quartz buffer(FMQ-2~FMQ-1).The second type is antigorite-serpentinites(Group2)represented by Ximaoshan and Wangchunwan blocks.They are non-pseudomorphic,with no primary framework silicate surviving.Fertile compositions(i.e.,higher Al_(2)O_(3)and Al_(2)O_(3)/SiO_(2),nearly flat REE patterns)and conjoint enrichment of LILE with HFSE suggest melt/rock interaction.Negative Ce,Eu anomalies,and enriched U relative to alkaline elements demonstrate interactions with more oxidized seawater or seafloor fluids(FMQ~FMQ-1).Remarkable Sr negative anomalies may be attributed to Sr release during lizardite/antigorite transition in subduction zone,indicating interaction with low-Sr slab fluids.We propose that Group 2 serpentinites originate either from mantle wedge or abyssal peridotites,refertilized by mantle melts,then hydrated in seafloor or shallow forearc and entrapped into subduction channel.Combined with geochronology and tectonic constraints of associated eclogites in Hong'an terrane,the two types of serpentinites may correlate with subduction of different oceanic basins during the late Paleozoic and/or Proterozoic eras.It raises possibility of defining an ophiolitic setting in Hong'an Orogen for which further evidence is required.展开更多
To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the...To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.展开更多
For the first time, fluid-melt inclusions are found in fluorite of the Huanggangliang skarn iron-tin deposit (HSID). The fluorite was formed in the main stage of mineralization, named the hydro-skarnization stage. The...For the first time, fluid-melt inclusions are found in fluorite of the Huanggangliang skarn iron-tin deposit (HSID). The fluorite was formed in the main stage of mineralization, named the hydro-skarnization stage. The inclusions contain various components such as Fe, Mg and Cr from deep sources. The melts of primary inclusions are mainly Ca- and F-rich and those of secondary inclusions tend to become Si-rich. During this evolution process, the melts and iron daughter minerals decreased and even vanished. These facts reveal that the evolution of the primary mineralizing fluids and the differentiation of the fluids and melts are the main factors leading to the deposition of Fe, Sn and other elements. This discovery confirms the magmatic genesis of the HSID and has filled in the gaps in the research of magmatogenic skarn deposits and furnished new methods for such research. Furthermore, it has enlarged the scope of the research on fluid inclusions.展开更多
Melting heat transfer in the boundary layer flow of a couple stress fluid over a stretching surface is investigated. The developed differential equations are solved for homotopic solutions. It is observed that the vel...Melting heat transfer in the boundary layer flow of a couple stress fluid over a stretching surface is investigated. The developed differential equations are solved for homotopic solutions. It is observed that the velocity and the boundary layer thickness are decreasing functions of the couple stress fluid parameter. However, the temperature and surface heat transfer increase when the values of the couple stress fluid parameter increase. The velocity and temperature fields increase with an increase in the melting process of the stretching sheet.展开更多
The effect of melting heat transfer on the two dimensional boundary layer flow of a micropolar fluid near a stagnation point embedded in a porous medium in the presence of internal heat generation/absorption is invest...The effect of melting heat transfer on the two dimensional boundary layer flow of a micropolar fluid near a stagnation point embedded in a porous medium in the presence of internal heat generation/absorption is investigated. The governing non-linear partial differential equations describing the problem are reduced to a system of non-linear ordinary differential equations using similarity transformations solved numerically using the Chebyshev spectral method. Numerical results for velocity, angular velocity and temperature profiles are shown graphically and discussed for different values of the inverse Darcy number, the heat generation/absorption parameter, and the melting parameter. The effects of the pertinent parameters on the local skin-friction coefficient, the wall couple stress, and the local Nusselt number are tabulated and discussed. The results show that the inverse Darcy number has the effect of enhancing both velocity and temperature and suppressing angular velocity. It is also found that the local skin-friction coefficient decreases, while the local Nusselt number increases as the melting parameter increases.展开更多
This paper presents a direct study of the fluids and melts in the upper mantle by examining the fluid inclusions, melt inclusions and glasses trapped in the mantle lherzolite xenoliths entrained by Cenozoic alkali bas...This paper presents a direct study of the fluids and melts in the upper mantle by examining the fluid inclusions, melt inclusions and glasses trapped in the mantle lherzolite xenoliths entrained by Cenozoic alkali basalts (basanite, olivine-nephelinite and alkali-olivine basalt) from eastern China. The study indicates that the volatile components, which are dissolved in high-pressure solid mineral phases of mantle peridotite at depths, may be exsolved under decompressive conditions of mantle plume upwelling to produce the initial free fluid phases in the upper mantle. The free fluid phases migrating in the upper mantle may result in lowering of the mantle solidus (and liquidus), thereby initiating partial melting of the upper mantle, and in the meantime, producing metasomatic effects on the latter.展开更多
The partition coefficients of W,Nb,and Ta between the P-rich peraluminous granitic melt and the coexisting aqueous fluid were determined at 800-850 °C and 0.5-1.5 kbar.The experimental results showed that the par...The partition coefficients of W,Nb,and Ta between the P-rich peraluminous granitic melt and the coexisting aqueous fluid were determined at 800-850 °C and 0.5-1.5 kbar.The experimental results showed that the partition coefficients D_w,D_(Nb) and D_(Ta)(D_i^(v/m) = C_i^V/C_i^m,where C_i^V and C_i^m denote the concentrations of an element,i,in the aqueous fluid and the melt,respectively) were less than 0.1.All partition coefficients were affected by pressure,but there was no evidence for the complexation of P2O5 with these elements in the granitic melt or aqueous fluid,except for with W in the fluid.The results showed that W,Nb,and Ta tended to partition into the granitic melt and,in the late period of crystallization of P-rich magma,they formed independent minerals.展开更多
Liquid-liquid immiscibility has crucial influences on geological processes,such as magma degassing and formation of ore deposits.Sulfate,as an important component,associates with many kinds of deposits.Two types of im...Liquid-liquid immiscibility has crucial influences on geological processes,such as magma degassing and formation of ore deposits.Sulfate,as an important component,associates with many kinds of deposits.Two types of immiscibility,including(i)fluid-melt immiscibility between an aqueous solution and a sulfate melt,and(ii)fluid-fluid immiscibility between two aqueous fluids with different sulfate concentrations,have been identified for sulfate-water systems.In this study,we investigated the immiscibility behaviors of a sulfate-and quartz-saturated Na_(2)SO_(4)-SiO_(2)-H_(2)O system at elevated temperature,to explore the phase relationships involving both types of immiscibility.The fluid-melt immiscibility appeared first when the Na_(2)SO_(4)-SiO_(2)-H_(2)O sample was heated to~270℃,and then fluid-fluid immiscibility emerged while the sample was further heated to~450℃.At this stage,the coexistence of one water-saturated sulfate melt and two aqueous fluids with distinct sulfate concentrations was observed.The three immiscible phases remain stable over a wide pressure-temperature range,and the appearance temperature of the fluid-fluid immiscibility increases with the increased pressure.Considering that sulfate components occur extensively in carbonatite-related deposits,the fluid-fluid immiscibility can result in significant sulfate fractionation and provides implications for understanding the formation of carbonatite-related rare earth deposits.展开更多
Abundant fluid-melt inc1usions are found in the aegirine-augite-barite pegmatite andcarbonatite veins in the Mianning REE deposit, Sichuan. They were trapped in early stage flu-orite and quartz from a salt-melt system...Abundant fluid-melt inc1usions are found in the aegirine-augite-barite pegmatite andcarbonatite veins in the Mianning REE deposit, Sichuan. They were trapped in early stage flu-orite and quartz from a salt-melt system at temperatures higher than 500℃. Meanwhile, fluidinclusions are also present in large amounts in bastnaesite. Homogenized between 150 and270℃, these inclusions are thought to be representative of the physiccrchemical conditions ofREE minera1ization. These results show that the Mianning REE deposit is of tyPical hy-drothermal origin developed from a salt-melt system.展开更多
Experiments on partial melting of mantle lherzolite have been realized at 0.6 and 1.0 GPa and the chemical compositional variations of melts during different melting stages have been first discussed. The results show ...Experiments on partial melting of mantle lherzolite have been realized at 0.6 and 1.0 GPa and the chemical compositional variations of melts during different melting stages have been first discussed. The results show that the trends of variations in SiO2, CaO, Al2O3, Na2O and TiO2 are different at different melting stages. The melts produced at lower pressure are richer in SiO2 than those at higher pressure. The mantle-derived silica-rich fluids (silicate melts) are polygenetic, but the basic and intermediate-acid silicate melts in mantle peridotite xenoliths from the same host rocks, which have equivalent contents of volatile and alkali components and different contents of other components, should result from in-situ (low-degree) partial melting of mantle peridotite under different conditions (e.g. at different depths, with introduction of C-O-H fluids or in the presence of metasomatic minerals). The intermediate-acid melts may be the result of partial melting (at lower pressure) Opx + Sp + K-Na-rich fluid ±(Am-phi) ± (Phlog) = OI + melt. But the intermediate-acid magmas cannot be produced from the partial melting of normal mantle peridotite unless the crustal materials are introduced to some extent.展开更多
Experiments on the partitioning of Cu between different granitic silicate melts and the respective coexisting aqueous fluids have been performed under conditions of 850 ℃, 100 MPa and oxygen fugacity （fO2） buffered...Experiments on the partitioning of Cu between different granitic silicate melts and the respective coexisting aqueous fluids have been performed under conditions of 850 ℃, 100 MPa and oxygen fugacity （fO2） buffered at approaching Ni-NiO （NNO）. Partition coefficients of Cu （Dcu = Cfluid/Cmelt） were varied with different alumina/alkali mole ratios [Al2O3/（Na2O ＋ K2O）, abbreviated as Al/ Alk], Na/K mole ratios, and SiO2 mole contents. The DCu increased from 1.28 ± 0.01 to 22.18 ±0.22 with the increase of Al/Alk mole ratios （ranging from 0.64 to 1.20） and Na/K mole ratios （ranging from 0.58 to 2.56）. The experimental results also showed that Dcu was positively correlated with the HCl concentration of the starting fluid. The Dcu was independent of the SiO2 mole content in the range of SiO2 content considered. No Dcu value was less than 1 in our experiments at 850 ℃ and 100 MPa, indicating that Cu preferred to enter the fluid phase rather than the coexisting melt phase under most conditions in the melt-fluid system, and thus a significant amount of Cu could be transported in the fluid phase in the magmatichydrothermal environment. The results indicated that Cu favored partitioning into the aqueous fluid rather than the melt phase if there was a high Na/K ratio, Na-rich, peraluminous granitic melt coexisting with the high Cl^- fluid.展开更多
Supercritical fluid and granitic melt are commonly generated as pressure decreases during exhumation of deeply subducted continental crust from mantle depths,promoting crust–mantle interaction,changing the rheology o...Supercritical fluid and granitic melt are commonly generated as pressure decreases during exhumation of deeply subducted continental crust from mantle depths,promoting crust–mantle interaction,changing the rheology of material along much of the subduction channel and,in a feedback loop,facilitating ongoing exhumation.However.展开更多
The objective of this article is to present the dynamics of an Upper Convected Maxwell (UCM) fluid flow with heat and mass transfer over a melting surface. The influence of melting heat transfer, thermal and solutal s...The objective of this article is to present the dynamics of an Upper Convected Maxwell (UCM) fluid flow with heat and mass transfer over a melting surface. The influence of melting heat transfer, thermal and solutal stratification are properly accounted for by modifying the classical boundary conditions of temperature and concentration respectively. It is assumed that the ratio of inertia forces to viscous forces is high enough for boundary layer approximation to be valid. The corresponding influence of exponential space dependent internal heat source on viscosity and thermal conductivity of UCM is properly considered. The dynamic viscosity and thermal conductivity of UCM are temperature dependent. Classical temperature dependent viscosity and thermal conductivity models were modified to suit the case of both melting heat transfer and thermal stratification. The governing non-linear partial differential equations describing the problem are reduced to a system of nonlinear ordinary differential equations using similarity transformations and completed the solution numerically using the Runge-Kutta method along with shooting technique. For accurate and correct analysis of the effect of variable viscosity on fluid flow in which (Tw or Tm) T∞ , the mathematical models of variable viscosity and thermal conductivity must be modified.展开更多
This article addresses melting heat transfer in magnetohydrodynamics(MHD)nanofluid flows by a rotating disk. The analysis is performed in Cu-water and Ag-water nanofluids. Thermal radiation, viscous dissipation, and c...This article addresses melting heat transfer in magnetohydrodynamics(MHD)nanofluid flows by a rotating disk. The analysis is performed in Cu-water and Ag-water nanofluids. Thermal radiation, viscous dissipation, and chemical reactions impacts are added in the nanofluid model. Appropriate transformations lead to the nondimensionalized boundary layer equations. Series solutions for the resulting equations are computed.The role of pertinent parameters on the velocity, temperature, and concentration is analyzed in the outputs. It is revealed that the larger melting parameter enhances the velocity profile while the temperature profile decreases. The surface drag force and heat transfer rate are computed under the influence of pertinent parameters. Furthermore, the homogeneous reaction parameter serves to decrease the surface concentration.展开更多
The metallurgical structure and composition of ingots which depend critically on the fluid motion within the molten pool during the vacuum arc remelting(VAR)process have important effect on the subsequent mechanical p...The metallurgical structure and composition of ingots which depend critically on the fluid motion within the molten pool during the vacuum arc remelting(VAR)process have important effect on the subsequent mechanical processes like forging,rolling and welding.In order to determine the fluid motion of molten pool,a 2D finite element model is established using ANSYS10.0 software,combined with the turbulent fluid flow and heat transfer.The fluid motion caused by thermo buoyancy forces is investigated at different VAR processes in the present study.The results indicate that the fluid flows symmetrically along the axis of the molten pool and clockwisely along the circle at the right pool’s profile.It is also shown that the maximum velocity increases with increasing melting rate and a direct proportional relationship exists.展开更多
Understanding the flow characteristics of amorphous metal melts is important for casting and molding processes.Fluidity of Zr-based amorphous metal melts was determined by using a self-designed apparatus.Phase analysi...Understanding the flow characteristics of amorphous metal melts is important for casting and molding processes.Fluidity of Zr-based amorphous metal melts was determined by using a self-designed apparatus.Phase analysis demonstrated that the fluidity test samples were fuUy amorphous structure.The onset crystallization temperature significantly moved toward high temperature with the increases of casting temperature,which improved the glass-forming ability and thermal stability of Zr-based amorphous metal.Fluidity test results demonstrated that the fluidity length increased monotonically with the increases of temperature,pressure,and runner diameter.By identifying the types and quantities of the defect in castings,it could conclude that smooth filling processes occurred under appropriate conditions.Experimental results indicated that the flow behavior of the Zr-based amorphous metal melts strongly depended on the casting temperature and equivalent thickness.Constitutive equation based on Newton's law of heat exchange and Rayleigh rule was established to'evaluate the fluidity of Zr-based amorphous metal melts.Theoretical calculations and experimental tests were basically coincided with each other.The determined optimal casting temperatures and equivalent thicknesses were adopted to successfully fabricate a series of fully shaped castings through gravity casting.展开更多
Based on the Eulerian-Lagrangian approach,a mathematical model was established to describe the gas-liquid flow behavior in the Ruhrstahl-Heraeus(RH)degasser.The momentum source and the turbulent kinetic energy source ...Based on the Eulerian-Lagrangian approach,a mathematical model was established to describe the gas-liquid flow behavior in the Ruhrstahl-Heraeus(RH)degasser.The momentum source and the turbulent kinetic energy source due to the motion of gas bubbles were considered for the liquid flow.The effect of the expansion of gas bubbles on the liquid velocity,recirculation rate,and mixing time was quantitatively evaluated.After the fluid flow reached the steady state,the melting and mixing processes of aluminum alloys in the RH degasser were also investigated.The results indicate that the expansion of gas bubbles has a significant infuence on the recirculation rate and the mixing time in the RH process.Increasing the superheat of liquid steel and decreasing the initial diameter of alloy particles are beneficial to promote the melting and mixing of alloy particles.Due to the existence of solidified steel shells,the maximum diameter of the alloy particle is about 1.5 times its initial diameter.展开更多
The cellular structured titanium alloys have attracted significant attention for implants because of their lower Young’s modulus,which is comparable to human bone and has the capability of providing space for bone ti...The cellular structured titanium alloys have attracted significant attention for implants because of their lower Young’s modulus,which is comparable to human bone and has the capability of providing space for bone tissue in-growth.However,there is a gap in the knowledge in regard to the relationship between the pore characteristics and the electrochemical performance of open-cellular structured titanium alloys.In this study,we elucidate the influence of pore characteristics on the electrochemical performance of open-cellular structured Ti-6Al-4V alloys produced by electron beam melting(EBM).Intriguingly,the passive film formed on cellular structured Ti-6Al-4V alloy with a larger pore size was more stable and protective,and the corrosion performance was superior compared to the samples with a smaller pore size in phosphate buffered saline(PBS),mainly because of relatively smaller exposed surface area and unlimited flow of electrolyte.However,in acidic PBS containing fluoride ions,the pore characteristics did not play an important role in the corrosion resistance.It was considered that the protective film breaks down such that the corrosion performance of cellular structured alloys was comparable to each other in this harsh environment.展开更多
Rare element mineralized granites of me Yanshan period in Southern China are characterized by high contents of SiO2,Na2o,K2O,and F and are enriched in Nb,Ta,REE,W,Sn,Be and Li .Opinions differed over whether they are ...Rare element mineralized granites of me Yanshan period in Southern China are characterized by high contents of SiO2,Na2o,K2O,and F and are enriched in Nb,Ta,REE,W,Sn,Be and Li .Opinions differed over whether they are of metasomatk or magmatic origin .In this paper ,we present results of a study on melt and fluid inclusions in topaz-albite feldspar granite from Limo Nb-Ta-W-Sn granite and 414 Ta-Li albhe granite .Our data, which come from 15 mineralized granites, provide strong support magmatic origin .Mett inclusions are recognized in both topaz and quartz, and are associated with primary gas-rich incluaons.Crystallites of a Nb (Ta) -bearing mineral and cassiterite are also commonly present as inclusions in the topaz .Multiphase (mett+fluid) inclusions are observed in some quartz from granites and granite-related pegmatite .Mett inclusions start to mett at a temperature of approximately 540 ℃ in topaz and 650 ℃ in quartz .Final homogenization temperature is 700-900 ℃ in quartz ,700-800℃ in topaz and 440-550 ℃ for primary gas-rich inclusions coexisting with mett inclusions in topaz .The fluid inclusion data show that there was a continuous evobtion of the fluid from Nb-Ta granites and pegmatites to W-Sh hydrothermal vein. The coexistence of mett .vapour-rich fluid inclusions, and rare element crystaffites in topaz and quartz indicates that these minerals crystallized from a vapour-saturated mett enriched in Na.K,F and rare elements (Li,Be,Nb,Ta) .The evidence from fluid inclusion study shows that the possible genesis of the rare dement mineralization inLi-F granites of Yanshan period in Southern China results from magmatic differentiation .展开更多
The three-dimensional physical model of the randomly packed powder material irradiated by the laser beam was established,taking into account the transformation of the material phase,the melt spreading and the interact...The three-dimensional physical model of the randomly packed powder material irradiated by the laser beam was established,taking into account the transformation of the material phase,the melt spreading and the interaction of the free surface of the molten pool and the recoiling pressure caused by the material evaporation during the selective laser melting.Influence of the processing parameters on the thermal behavior,the material evaporation,the surface morphology and the densification behavior in the connection region of the molten pool and the substrate was studied.It was shown that the powder material underwent the transformation from the partial melting state to the complete melting state and finally to the overheating state with the applied laser energy density increasing from 167 J/mm^(3) to 417 J/mm^(3).Therefore,the solidified track ranged from the discontinuous tracks with the rough surface to the continuous tracks with residual porosities,then to the continuous and dense tracks and terminally to the fluctuated tracks with the increase in the laser energy density.Meanwhile,the laser energy effect depth was maintained the positive relationship with the laser energy density.The vortex velocity obtained in the free surface of the molten pool towards to the rear region in the opposite laser scan direction promoted the melt convection to the edge region of the molten pool as the laser energy density was higher than 277 J/mm^(3),demonstrating the efficient energy dissipation from the center of the irradiation region to the whole part of the molten pool and the attendant production of the sufficient melt volume.Therefore,the efficient spreading of the molten pool and the metallurgical bonding ability of the melt with the substrate was obtained at the optimized laser energy density of 277 J/mm^(3).However,the severe material evaporation would take place as the melt was overheated,resulting in the formation of the residual pores and poor surface quality.展开更多
基金funded by the National Natural Science Foundation of China(No.42130309)China Geological Survey(Nos.DD20160030,DD20190050)。
文摘A cluster of serpentinite bodies has been recognized tectonically emplaced within the greenschist-amphibolite-facies metamorphic terrane in Hong'an,western Dabie orogen,central China.Two types of serpentinites are identified on the basis of integrated petrographic,mineralogical and geochemical study.The first type,represented by Yinshanzhai serpentinite complex(Group 1)comprises heterogeneous lithology as a massive serpentinite matrix“intruded”by antigoriteenriched serpentinite lenses.They are both pseudomorphic textured with different mineral assemblages indicating an increasing temperature-pressure condition.Serpentinite matrix(Group 1a)is chemically characterized by high MgO/SiO_(2)and low Al_(2)O_(3)/SiO_(2),Ti and Ca contents,suggesting a depleted mantle wedge origin.The coexistence of compositionally-heterogeneous chromite with highCr^(#)(0.78-0.96)and intermediate-Cr^(#)(0.59-0.70)pristine cores indicates extensive mantle melting.Meanwhile,extremely high Fo olivine relicts(96-97)with considerably higher MnO and lower NiO contents than mantle olivine indicate that they are metamorphic products from serpentine decomposition.Accordingly,we propose that Yinshanzhai serpentinite complex experienced two distinct episodes of hydration.The serpentinite lenses(Group 1b)show higher SiO_(2)and lower MgO concentrations.Nevertheless,the trace elements of groups 1a and 1b are consistent:U-shaped REE patterns,positive Eu anomalies and enrichment of LILE(i.e.,Cs,U)are all identified as forearc properties.They are affected by reducing slab-derived fluids in forearc mantle,with f_(O2)of 1 to 2 logarithmic units below f_(O2)of fayalite-magnetite-quartz buffer(FMQ-2~FMQ-1).The second type is antigorite-serpentinites(Group2)represented by Ximaoshan and Wangchunwan blocks.They are non-pseudomorphic,with no primary framework silicate surviving.Fertile compositions(i.e.,higher Al_(2)O_(3)and Al_(2)O_(3)/SiO_(2),nearly flat REE patterns)and conjoint enrichment of LILE with HFSE suggest melt/rock interaction.Negative Ce,Eu anomalies,and enriched U relative to alkaline elements demonstrate interactions with more oxidized seawater or seafloor fluids(FMQ~FMQ-1).Remarkable Sr negative anomalies may be attributed to Sr release during lizardite/antigorite transition in subduction zone,indicating interaction with low-Sr slab fluids.We propose that Group 2 serpentinites originate either from mantle wedge or abyssal peridotites,refertilized by mantle melts,then hydrated in seafloor or shallow forearc and entrapped into subduction channel.Combined with geochronology and tectonic constraints of associated eclogites in Hong'an terrane,the two types of serpentinites may correlate with subduction of different oceanic basins during the late Paleozoic and/or Proterozoic eras.It raises possibility of defining an ophiolitic setting in Hong'an Orogen for which further evidence is required.
基金National Natural Science Foundation of China(51504138,51674118,52271177)Hunan Provincial Natural Science Foundation of China(2023JJ50181)Supported by State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(P2024-022)。
文摘To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.
文摘For the first time, fluid-melt inclusions are found in fluorite of the Huanggangliang skarn iron-tin deposit (HSID). The fluorite was formed in the main stage of mineralization, named the hydro-skarnization stage. The inclusions contain various components such as Fe, Mg and Cr from deep sources. The melts of primary inclusions are mainly Ca- and F-rich and those of secondary inclusions tend to become Si-rich. During this evolution process, the melts and iron daughter minerals decreased and even vanished. These facts reveal that the evolution of the primary mineralizing fluids and the differentiation of the fluids and melts are the main factors leading to the deposition of Fe, Sn and other elements. This discovery confirms the magmatic genesis of the HSID and has filled in the gaps in the research of magmatogenic skarn deposits and furnished new methods for such research. Furthermore, it has enlarged the scope of the research on fluid inclusions.
基金supported by the Deanship of Scientific Research(DSR),King Abdulaziz University,Jeddah,Saudi Arabia
文摘Melting heat transfer in the boundary layer flow of a couple stress fluid over a stretching surface is investigated. The developed differential equations are solved for homotopic solutions. It is observed that the velocity and the boundary layer thickness are decreasing functions of the couple stress fluid parameter. However, the temperature and surface heat transfer increase when the values of the couple stress fluid parameter increase. The velocity and temperature fields increase with an increase in the melting process of the stretching sheet.
文摘The effect of melting heat transfer on the two dimensional boundary layer flow of a micropolar fluid near a stagnation point embedded in a porous medium in the presence of internal heat generation/absorption is investigated. The governing non-linear partial differential equations describing the problem are reduced to a system of non-linear ordinary differential equations using similarity transformations solved numerically using the Chebyshev spectral method. Numerical results for velocity, angular velocity and temperature profiles are shown graphically and discussed for different values of the inverse Darcy number, the heat generation/absorption parameter, and the melting parameter. The effects of the pertinent parameters on the local skin-friction coefficient, the wall couple stress, and the local Nusselt number are tabulated and discussed. The results show that the inverse Darcy number has the effect of enhancing both velocity and temperature and suppressing angular velocity. It is also found that the local skin-friction coefficient decreases, while the local Nusselt number increases as the melting parameter increases.
基金supported by the National NaturalScience Foundation of China(Grant 4913390).
文摘This paper presents a direct study of the fluids and melts in the upper mantle by examining the fluid inclusions, melt inclusions and glasses trapped in the mantle lherzolite xenoliths entrained by Cenozoic alkali basalts (basanite, olivine-nephelinite and alkali-olivine basalt) from eastern China. The study indicates that the volatile components, which are dissolved in high-pressure solid mineral phases of mantle peridotite at depths, may be exsolved under decompressive conditions of mantle plume upwelling to produce the initial free fluid phases in the upper mantle. The free fluid phases migrating in the upper mantle may result in lowering of the mantle solidus (and liquidus), thereby initiating partial melting of the upper mantle, and in the meantime, producing metasomatic effects on the latter.
基金supported by the Chinese National Natural Science Foundation(Project No.40273030)the Chinese Academy of Sciences through an innovation project (Project No.KZCX3-SW-124)
文摘The partition coefficients of W,Nb,and Ta between the P-rich peraluminous granitic melt and the coexisting aqueous fluid were determined at 800-850 °C and 0.5-1.5 kbar.The experimental results showed that the partition coefficients D_w,D_(Nb) and D_(Ta)(D_i^(v/m) = C_i^V/C_i^m,where C_i^V and C_i^m denote the concentrations of an element,i,in the aqueous fluid and the melt,respectively) were less than 0.1.All partition coefficients were affected by pressure,but there was no evidence for the complexation of P2O5 with these elements in the granitic melt or aqueous fluid,except for with W in the fluid.The results showed that W,Nb,and Ta tended to partition into the granitic melt and,in the late period of crystallization of P-rich magma,they formed independent minerals.
基金funded by the National Natural Science Foundation of China(Grant nos.41930427,41872078,and 41502069)the Young Elite Scientists Sponsorship Program by CAST(Grant no.YESS20180143)the Fundamental Research Funds for the Central Universities(Grant nos.FRF-TP-18-017A3 and FRF-IDRY-19-001)。
文摘Liquid-liquid immiscibility has crucial influences on geological processes,such as magma degassing and formation of ore deposits.Sulfate,as an important component,associates with many kinds of deposits.Two types of immiscibility,including(i)fluid-melt immiscibility between an aqueous solution and a sulfate melt,and(ii)fluid-fluid immiscibility between two aqueous fluids with different sulfate concentrations,have been identified for sulfate-water systems.In this study,we investigated the immiscibility behaviors of a sulfate-and quartz-saturated Na_(2)SO_(4)-SiO_(2)-H_(2)O system at elevated temperature,to explore the phase relationships involving both types of immiscibility.The fluid-melt immiscibility appeared first when the Na_(2)SO_(4)-SiO_(2)-H_(2)O sample was heated to~270℃,and then fluid-fluid immiscibility emerged while the sample was further heated to~450℃.At this stage,the coexistence of one water-saturated sulfate melt and two aqueous fluids with distinct sulfate concentrations was observed.The three immiscible phases remain stable over a wide pressure-temperature range,and the appearance temperature of the fluid-fluid immiscibility increases with the increased pressure.Considering that sulfate components occur extensively in carbonatite-related deposits,the fluid-fluid immiscibility can result in significant sulfate fractionation and provides implications for understanding the formation of carbonatite-related rare earth deposits.
文摘Abundant fluid-melt inc1usions are found in the aegirine-augite-barite pegmatite andcarbonatite veins in the Mianning REE deposit, Sichuan. They were trapped in early stage flu-orite and quartz from a salt-melt system at temperatures higher than 500℃. Meanwhile, fluidinclusions are also present in large amounts in bastnaesite. Homogenized between 150 and270℃, these inclusions are thought to be representative of the physiccrchemical conditions ofREE minera1ization. These results show that the Mianning REE deposit is of tyPical hy-drothermal origin developed from a salt-melt system.
文摘Experiments on partial melting of mantle lherzolite have been realized at 0.6 and 1.0 GPa and the chemical compositional variations of melts during different melting stages have been first discussed. The results show that the trends of variations in SiO2, CaO, Al2O3, Na2O and TiO2 are different at different melting stages. The melts produced at lower pressure are richer in SiO2 than those at higher pressure. The mantle-derived silica-rich fluids (silicate melts) are polygenetic, but the basic and intermediate-acid silicate melts in mantle peridotite xenoliths from the same host rocks, which have equivalent contents of volatile and alkali components and different contents of other components, should result from in-situ (low-degree) partial melting of mantle peridotite under different conditions (e.g. at different depths, with introduction of C-O-H fluids or in the presence of metasomatic minerals). The intermediate-acid melts may be the result of partial melting (at lower pressure) Opx + Sp + K-Na-rich fluid ±(Am-phi) ± (Phlog) = OI + melt. But the intermediate-acid magmas cannot be produced from the partial melting of normal mantle peridotite unless the crustal materials are introduced to some extent.
文摘Experiments on the partitioning of Cu between different granitic silicate melts and the respective coexisting aqueous fluids have been performed under conditions of 850 ℃, 100 MPa and oxygen fugacity （fO2） buffered at approaching Ni-NiO （NNO）. Partition coefficients of Cu （Dcu = Cfluid/Cmelt） were varied with different alumina/alkali mole ratios [Al2O3/（Na2O ＋ K2O）, abbreviated as Al/ Alk], Na/K mole ratios, and SiO2 mole contents. The DCu increased from 1.28 ± 0.01 to 22.18 ±0.22 with the increase of Al/Alk mole ratios （ranging from 0.64 to 1.20） and Na/K mole ratios （ranging from 0.58 to 2.56）. The experimental results also showed that Dcu was positively correlated with the HCl concentration of the starting fluid. The Dcu was independent of the SiO2 mole content in the range of SiO2 content considered. No Dcu value was less than 1 in our experiments at 850 ℃ and 100 MPa, indicating that Cu preferred to enter the fluid phase rather than the coexisting melt phase under most conditions in the melt-fluid system, and thus a significant amount of Cu could be transported in the fluid phase in the magmatichydrothermal environment. The results indicated that Cu favored partitioning into the aqueous fluid rather than the melt phase if there was a high Na/K ratio, Na-rich, peraluminous granitic melt coexisting with the high Cl^- fluid.
基金supported by the National Natural Science Foundation of China(42072228,41572182,41272225)the project from Chinese Ministry of Education(BP071922)
文摘Supercritical fluid and granitic melt are commonly generated as pressure decreases during exhumation of deeply subducted continental crust from mantle depths,promoting crust–mantle interaction,changing the rheology of material along much of the subduction channel and,in a feedback loop,facilitating ongoing exhumation.However.
文摘The objective of this article is to present the dynamics of an Upper Convected Maxwell (UCM) fluid flow with heat and mass transfer over a melting surface. The influence of melting heat transfer, thermal and solutal stratification are properly accounted for by modifying the classical boundary conditions of temperature and concentration respectively. It is assumed that the ratio of inertia forces to viscous forces is high enough for boundary layer approximation to be valid. The corresponding influence of exponential space dependent internal heat source on viscosity and thermal conductivity of UCM is properly considered. The dynamic viscosity and thermal conductivity of UCM are temperature dependent. Classical temperature dependent viscosity and thermal conductivity models were modified to suit the case of both melting heat transfer and thermal stratification. The governing non-linear partial differential equations describing the problem are reduced to a system of nonlinear ordinary differential equations using similarity transformations and completed the solution numerically using the Runge-Kutta method along with shooting technique. For accurate and correct analysis of the effect of variable viscosity on fluid flow in which (Tw or Tm) T∞ , the mathematical models of variable viscosity and thermal conductivity must be modified.
文摘This article addresses melting heat transfer in magnetohydrodynamics(MHD)nanofluid flows by a rotating disk. The analysis is performed in Cu-water and Ag-water nanofluids. Thermal radiation, viscous dissipation, and chemical reactions impacts are added in the nanofluid model. Appropriate transformations lead to the nondimensionalized boundary layer equations. Series solutions for the resulting equations are computed.The role of pertinent parameters on the velocity, temperature, and concentration is analyzed in the outputs. It is revealed that the larger melting parameter enhances the velocity profile while the temperature profile decreases. The surface drag force and heat transfer rate are computed under the influence of pertinent parameters. Furthermore, the homogeneous reaction parameter serves to decrease the surface concentration.
基金the National Basic Research Program (973) of China(No.2007CB613802)
文摘The metallurgical structure and composition of ingots which depend critically on the fluid motion within the molten pool during the vacuum arc remelting(VAR)process have important effect on the subsequent mechanical processes like forging,rolling and welding.In order to determine the fluid motion of molten pool,a 2D finite element model is established using ANSYS10.0 software,combined with the turbulent fluid flow and heat transfer.The fluid motion caused by thermo buoyancy forces is investigated at different VAR processes in the present study.The results indicate that the fluid flows symmetrically along the axis of the molten pool and clockwisely along the circle at the right pool’s profile.It is also shown that the maximum velocity increases with increasing melting rate and a direct proportional relationship exists.
基金National Natural Science Foundation of China(Nos.51671166,51827801 and 51434008)Youth Fund of the Education Department in Hebei Province (QN2018305).
文摘Understanding the flow characteristics of amorphous metal melts is important for casting and molding processes.Fluidity of Zr-based amorphous metal melts was determined by using a self-designed apparatus.Phase analysis demonstrated that the fluidity test samples were fuUy amorphous structure.The onset crystallization temperature significantly moved toward high temperature with the increases of casting temperature,which improved the glass-forming ability and thermal stability of Zr-based amorphous metal.Fluidity test results demonstrated that the fluidity length increased monotonically with the increases of temperature,pressure,and runner diameter.By identifying the types and quantities of the defect in castings,it could conclude that smooth filling processes occurred under appropriate conditions.Experimental results indicated that the flow behavior of the Zr-based amorphous metal melts strongly depended on the casting temperature and equivalent thickness.Constitutive equation based on Newton's law of heat exchange and Rayleigh rule was established to'evaluate the fluidity of Zr-based amorphous metal melts.Theoretical calculations and experimental tests were basically coincided with each other.The determined optimal casting temperatures and equivalent thicknesses were adopted to successfully fabricate a series of fully shaped castings through gravity casting.
基金support from the Open Fund of Anhui Province Key Laboratory of Metallurgical Engineering&Resources Recycling(Anhui University of Technol-ogy)(SKF21-05)the Open Fund of State Key Laboratory of New technology of Iron and Steel Metallurgy(KF21-03)the National Natural Science Foundation of China(Grant Nos.51704005 and 51804003).
文摘Based on the Eulerian-Lagrangian approach,a mathematical model was established to describe the gas-liquid flow behavior in the Ruhrstahl-Heraeus(RH)degasser.The momentum source and the turbulent kinetic energy source due to the motion of gas bubbles were considered for the liquid flow.The effect of the expansion of gas bubbles on the liquid velocity,recirculation rate,and mixing time was quantitatively evaluated.After the fluid flow reached the steady state,the melting and mixing processes of aluminum alloys in the RH degasser were also investigated.The results indicate that the expansion of gas bubbles has a significant infuence on the recirculation rate and the mixing time in the RH process.Increasing the superheat of liquid steel and decreasing the initial diameter of alloy particles are beneficial to promote the melting and mixing of alloy particles.Due to the existence of solidified steel shells,the maximum diameter of the alloy particle is about 1.5 times its initial diameter.
基金partial support from the National Key Research and Development Program of China(Nos.2017YFC1104902,2016YFC1100502 and 2018YFC1105503)the National Natural Science Foundation of China(Nos.51871220 and 51631007)+3 种基金the Key Research Program of Frontier Sciences,CAS(No.QYZDJ-SSW-JSC031-02)the Natural Science Foundation of Liaoning Province of China(No.2019-MS-327 and 2020-KF-14-01)the State Key Laboratory of Light Alloy Casting Technology for Highend Equipment(No.LACT-007)the Shenyang Talents Program(No.RC200230)。
文摘The cellular structured titanium alloys have attracted significant attention for implants because of their lower Young’s modulus,which is comparable to human bone and has the capability of providing space for bone tissue in-growth.However,there is a gap in the knowledge in regard to the relationship between the pore characteristics and the electrochemical performance of open-cellular structured titanium alloys.In this study,we elucidate the influence of pore characteristics on the electrochemical performance of open-cellular structured Ti-6Al-4V alloys produced by electron beam melting(EBM).Intriguingly,the passive film formed on cellular structured Ti-6Al-4V alloy with a larger pore size was more stable and protective,and the corrosion performance was superior compared to the samples with a smaller pore size in phosphate buffered saline(PBS),mainly because of relatively smaller exposed surface area and unlimited flow of electrolyte.However,in acidic PBS containing fluoride ions,the pore characteristics did not play an important role in the corrosion resistance.It was considered that the protective film breaks down such that the corrosion performance of cellular structured alloys was comparable to each other in this harsh environment.
文摘Rare element mineralized granites of me Yanshan period in Southern China are characterized by high contents of SiO2,Na2o,K2O,and F and are enriched in Nb,Ta,REE,W,Sn,Be and Li .Opinions differed over whether they are of metasomatk or magmatic origin .In this paper ,we present results of a study on melt and fluid inclusions in topaz-albite feldspar granite from Limo Nb-Ta-W-Sn granite and 414 Ta-Li albhe granite .Our data, which come from 15 mineralized granites, provide strong support magmatic origin .Mett inclusions are recognized in both topaz and quartz, and are associated with primary gas-rich incluaons.Crystallites of a Nb (Ta) -bearing mineral and cassiterite are also commonly present as inclusions in the topaz .Multiphase (mett+fluid) inclusions are observed in some quartz from granites and granite-related pegmatite .Mett inclusions start to mett at a temperature of approximately 540 ℃ in topaz and 650 ℃ in quartz .Final homogenization temperature is 700-900 ℃ in quartz ,700-800℃ in topaz and 440-550 ℃ for primary gas-rich inclusions coexisting with mett inclusions in topaz .The fluid inclusion data show that there was a continuous evobtion of the fluid from Nb-Ta granites and pegmatites to W-Sh hydrothermal vein. The coexistence of mett .vapour-rich fluid inclusions, and rare element crystaffites in topaz and quartz indicates that these minerals crystallized from a vapour-saturated mett enriched in Na.K,F and rare elements (Li,Be,Nb,Ta) .The evidence from fluid inclusion study shows that the possible genesis of the rare dement mineralization inLi-F granites of Yanshan period in Southern China results from magmatic differentiation .
基金We are grateful for the financial support from the National Key Research and Development Program“Additive Manufacturing and Laser Manufacturing”(Nos.2016YFB1100101,2018YFB1106302)the National Natural Science Foundation of China(Nos.51790175,51735005)+3 种基金the Fundamental Research Funds for the Central Universities(No.NC2020004),the financial support from the Innovation Fund of National Engineering and Research Center for Commercial Aircraft Manufacturing(No.COMAC-SFGS-2016-33238)National Natural Science Foundation of China for Creative Research Groups(Grant No.51921003)The 15th Batch of“Six Talents Peaks”Innovative Talents Team Program“Laser Precise Additive Manufacturing of Structure-Performance Integrated Lightweight Alloy Components”(No.TD-GDZB-001)(Jiangsu Provincial Department of Human Resources and Social Security of China)2017 Excellent Scientific and Technological Innovation Teams of Universities in Jiangsu“Laser Additive Manufacturing Technologies for Metallic Components”(Jiangsu Provincial Department of Education of China).
文摘The three-dimensional physical model of the randomly packed powder material irradiated by the laser beam was established,taking into account the transformation of the material phase,the melt spreading and the interaction of the free surface of the molten pool and the recoiling pressure caused by the material evaporation during the selective laser melting.Influence of the processing parameters on the thermal behavior,the material evaporation,the surface morphology and the densification behavior in the connection region of the molten pool and the substrate was studied.It was shown that the powder material underwent the transformation from the partial melting state to the complete melting state and finally to the overheating state with the applied laser energy density increasing from 167 J/mm^(3) to 417 J/mm^(3).Therefore,the solidified track ranged from the discontinuous tracks with the rough surface to the continuous tracks with residual porosities,then to the continuous and dense tracks and terminally to the fluctuated tracks with the increase in the laser energy density.Meanwhile,the laser energy effect depth was maintained the positive relationship with the laser energy density.The vortex velocity obtained in the free surface of the molten pool towards to the rear region in the opposite laser scan direction promoted the melt convection to the edge region of the molten pool as the laser energy density was higher than 277 J/mm^(3),demonstrating the efficient energy dissipation from the center of the irradiation region to the whole part of the molten pool and the attendant production of the sufficient melt volume.Therefore,the efficient spreading of the molten pool and the metallurgical bonding ability of the melt with the substrate was obtained at the optimized laser energy density of 277 J/mm^(3).However,the severe material evaporation would take place as the melt was overheated,resulting in the formation of the residual pores and poor surface quality.
