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
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
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
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
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
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
In order to improve the tribological properties of titanium alloys,the in-situ TiN coatings were prepared by electrospark deposition（ESD） on the surface of TC11 titanium alloy.The effects of nitrogen flux on the mic...In order to improve the tribological properties of titanium alloys,the in-situ TiN coatings were prepared by electrospark deposition（ESD） on the surface of TC11 titanium alloy.The effects of nitrogen flux on the microstructure and tribological properties of TiN coatings were investigated.The results show that the coating is relative thin when the nitrogen flux is small and mainly consists of Ti2N,α-Ti,Ti O and TiN phases,and the metastable phase of Ti2N is developed due to the rapid solidification of ESD.While in excessive nitrogen flux condition,many micro-cracks and holes might be generated in the coating.In moderate nitrogen flux,the coating is mainly composed of TiN phase,and is dense and uniform（50-55 μm）.The average hardness is HV0.2 1165.2,which is 3.4 times that of the TC11 substrate.The TiN coatings prepared in moderate nitrogen flux perform the best wear resistance.The wear loss of the coating is 0.4 mg,which is 2/9 that of the TC11 substrate.The main wear mechanisms of the coatings are micro-cutting wear accompanied by multi-plastic deformation wear.展开更多
Cyclic thermal exposure tests of infrared heating to 800 ℃ in 120 s followed by compressed air cooling to 150 ℃ in 60 s were performed for the laser deposited Ti60A （Ti5.54Al3.38Sn3.34Zr0.37Mo0.46Si） alloy. The ef...Cyclic thermal exposure tests of infrared heating to 800 ℃ in 120 s followed by compressed air cooling to 150 ℃ in 60 s were performed for the laser deposited Ti60A （Ti5.54Al3.38Sn3.34Zr0.37Mo0.46Si） alloy. The effects of thermal exposure cycles on length ofβphase, area fraction ofαphase and microhardness of alloy were examined by OM, SEM and EDS. The results indicate that thermal exposure cycles have significant effects on length ofβphase, area fraction ofαphase and microhardness of the alloy. The original fine basket-weaveβand 78.5%αtransform to transient wedge-likeβ, finally leaving granularβand 97.6%coarsenedαwith the increased thermal exposure cycles. The formation mechanism of coarsenedαand broken-upβmicrostructure is discussed. The alloy after 750 thermal exposure cycles has the maximum microhardness, 33.3%higher than that of the as-deposited alloy.展开更多
A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibri...A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibrium shape was deposited on Cu substrates by hot-filament chemical vapor deposition（HF-CVD）,and the sp2 carbon content was less than 5.56%.The nucleation and growth of diamond film were investigated by micro-Raman spectroscopy,scanning electron microscopy,and X-ray diffraction.The results show that the nucleation density of diamond on the Ni-modified Cu substrates is 10 times higher than that on blank Cu substrates.The enhancement mechanism of the nucleation kinetics by Ni modification layer results from two effects：namely,the nanometer rough Ni-modified surface shows an improved absorption of nanodiamond particles that act as starting points for the diamond nucleation during HF-CVD process;the strong catalytic effect of the Ni-modified surface causes the formation of graphite layer that acts as an intermediate to facilitate diamond nucleation quickly.展开更多
The effects of carbon content (0.078-0.100 wt.%) on the microstructure and properties of 1000 MPa grade deposited metal produced by gas metal arc welding have been investigated. Experimental results show that the micr...The effects of carbon content (0.078-0.100 wt.%) on the microstructure and properties of 1000 MPa grade deposited metal produced by gas metal arc welding have been investigated. Experimental results show that the microstructure of the deposited metal was mainly composed of martensite, bainite and retained austenite. With increasing carbon content, the proportion of martensite increased, and the amount of bainite was reduced. High carbon content is beneficial to strength, but harmful to impact toughness, and thus, carbon reductions lead to the increase in impact toughness. When the carbon content was 0.100 wt.%, the lowest Charpy absorbed energy of 47 J at — 40℃ for the deposited metal was achieved, the highest yield strength of 1038 MPa was attained, and the yield-to-tensile ratio was more than 0.88, while the highest Charpy absorbed energy of 55.7 J at — 40℃ and the lowest yield strength of 915 MPa were obtained when the deposited metal contains 0.078 wt.% C, and the yield-to-tensile ratio was less than 0.85. It is concluded that bainite fraction and fine effective grain size were the dominant factors to achieve good comprehensive mechanical properties (the required strength and an acceptable toughness) of deposited metals with various carbon contents.展开更多
Alloy element and microstructure are key factors that dominate mechanical and corrosion resistant properties of weathering steel. The effect of Mo on microstructure, mechanical properties and corrosion resistant prope...Alloy element and microstructure are key factors that dominate mechanical and corrosion resistant properties of weathering steel. The effect of Mo on microstructure, mechanical properties and corrosion resistant property of depos ited metal was investigated. Experimental results show that with the increase of Mo content in deposited metals, the phase transformation temperature decreases, and the ferrite zone in CCT diagram moves rightward, resulting in en larged bainite zone and reduced ferrite and pearlite zone. The addition of 0.24 mass% Mo in deposited metal results in the increase of tensile strength, more M-A constituent and less high angle grain which reduce the low temperature toughness. It is found that Mo can raise the weathering resistance of deposited metal in industrial atmosphere. Analy sis indicates that Mo may enrich in the inner rust layer, produce MoO3, enhance the formation of compact rust film and impede the anode dissolution reaction. Granular bainite in deposited metals displays better corrosion resistance than acicular ferrite during the initial corrosion stage, but its long-term influence on the corrosion resistance is limited.展开更多
We report a case of sigmoid colonic carcinoma associated with deposited ova of Schistosoma japonicum. A 57-year old woman presented with a 10-mo history of left lower quadrant abdominal pain and a 2-mo history of bloo...We report a case of sigmoid colonic carcinoma associated with deposited ova of Schistosoma japonicum. A 57-year old woman presented with a 10-mo history of left lower quadrant abdominal pain and a 2-mo history of bloody stools. She had a significant past medical history of asymptomatic schistosomiasis japonica and constipation. A colonoscopy showed an exophytic fragile neoplasm with an ulcerating surface in the sigmoid colon. During the radical operative procedure, we noted the partially encircling tumor was located in the distal sigmoid colon, and extended into the serosa. Succedent pathological analysis demonstrated the diagnosis of sigmoid colonic ulcerative tubular adenocarcinoma, and showed deposited ova of Schistosoma japonicum in both tumor lesions and mesenteric lymph nodes. Three days after surgery the patient returned to the normal bowel function with one defecation per day. These findings reveal that deposited schistosome ova play a possible role in the carcinogenesis of colorectal cancer.展开更多
Organosilicone thin films have been deposited by plasma polymerization(pp)in a plasma enhanced chemical vapor deposition(PECVD)system using hexamethyldisilazane(HMDSN:C_(6)H_(19)Si_(2)N)as a monomer precursor,at diffe...Organosilicone thin films have been deposited by plasma polymerization(pp)in a plasma enhanced chemical vapor deposition(PECVD)system using hexamethyldisilazane(HMDSN:C_(6)H_(19)Si_(2)N)as a monomer precursor,at different biases of the stainless-steel substrate holder.The substrate bias affected film thickness,surface morphology,chemical composition and photoluminescence(PL)emission.For a negatively biased substrate,it is found that the film thickness is the minimum,while the porosity and PL emission are the maximum.For a positively biased substrate,the thickness and the ratio of Si/N are the maximum which correspond to a blue shift of the PL emission in comparison with the case of non-biased grounded substrate.In addition,the characterization of the plasma using a single cylindrical Langmuir probe has been performed to obtain information about both the electron density and the positive ion energy,where it can be concluded that the ion energy plays a major role in determining film thickness.展开更多
Effect of mechanical stress on magnetic properties of an exchange-biased ferromagnetic/antiferromagnetic bilayer deposited on a flexible substrate is investigated. The hysteresis loops with different magnitudes and or...Effect of mechanical stress on magnetic properties of an exchange-biased ferromagnetic/antiferromagnetic bilayer deposited on a flexible substrate is investigated. The hysteresis loops with different magnitudes and orientations of the stress can be classified into three types. The corresponding physical conditions for each type of the loop are deduced based on the principle of minimal energy. The equation of the critical stress is derived, which can judge whether the loops show hysteresis or not. Numerical calculations suggest that except for the magnitude of the mechanical stress, the relative orientation of the stress is also an important factor to tune the exchange bias effect.展开更多
In order to study deposited sediment settlement and consolidation mechanisms, sediment settlement experiments were conducted using a settlement column. Based on the experimental results, sediment settlement stage defi...In order to study deposited sediment settlement and consolidation mechanisms, sediment settlement experiments were conducted using a settlement column. Based on the experimental results, sediment settlement stage definition, excessive pore pressure （EPP） dissipation, and consolidation constitutive equations are discussed. Three stages, including the free settlement, hindered settlement, and self-weight consolidation settlement stages, are defined. The results of this study show that sediment settlement is mainly affected by the initial sediment concentration and initial settlement height, and the interface settlement rate is linearly attenuated with time on bilogarithmic scales during the hindered settlement and self-weight consolidation settlement stages. Moreover, the deposited sediment layer in the self-weight consolidation settlement stage experiences large strains, and the settlement amount in this stage is about 32% to 59% of the initial height of deposited sediment. EPP is nonlinearly distributed in the settlement direction, and consolidation settlement is faster than EPP dissipation in the self-weight consolidation settlement stage. Consolidation constitutive equations for the hydraulic conductivity and effective stress, applicable to large-strain consolidation calculation, were also determined and fitted in the power function form.展开更多
La-doped and undoped xBiIn03-（1 - x）PbTi03 （BI-PT） thin films are deposited on （101）SrRuO3/（lOO）Pt/（lO0） MgO substrates by the rf-magnetron sputtering method. The structures of the films are characterized by...La-doped and undoped xBiIn03-（1 - x）PbTi03 （BI-PT） thin films are deposited on （101）SrRuO3/（lOO）Pt/（lO0） MgO substrates by the rf-magnetron sputtering method. The structures of the films are characterized by XRD and SEM, and the results indicate that the thin films are grown with mainly （100） oriented and columnar structures. The ferroelectricity and piezoelectricity of the BI-PT films are also measured, and the measured results illustrate that both performances are effectively improved by the La-doping with suitable concentrations. These results will open up wide potential applications of the films in electronic devices.展开更多
In order to reduce sulphur （ S ） and phosphorus （ P ） impurities in deposited metal, a small amount of rare earth （RE） lanthanum （ La） and yttrium （Y） were added into the coating ofE4303 electrode, a low car...In order to reduce sulphur （ S ） and phosphorus （ P ） impurities in deposited metal, a small amount of rare earth （RE） lanthanum （ La） and yttrium （Y） were added into the coating ofE4303 electrode, a low carbon steel electrode. The microstructures of deposited metal were analyzed with metalloscope, and then the content of S and P was examined by energy dispenive X-ray spectrometer （ EDXS ）, and by wavelength dispersive X-ray fluorescence （XRF） spectrometer for further examination. The results show that the proper addition of La and Y can be beneficial to the desulfurization and dephosphorization of the deposited metal. Certainly, difference in the addition amount of La and Y could lead to various desulfurization and dephosphorization efficiency, in which the former is more obvious than the latter. With the proper amount of La attd Y, there is finer microstructure in deposited metal, and mechanical properties are improved as well. The S content in deposited metal with added La and Y decreases by 44. 44 wt. % , while the P content 6. 67 wt. %, compared with that in deposited metal without La and II.展开更多
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 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 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 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.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.
文摘In order to improve the tribological properties of titanium alloys,the in-situ TiN coatings were prepared by electrospark deposition（ESD） on the surface of TC11 titanium alloy.The effects of nitrogen flux on the microstructure and tribological properties of TiN coatings were investigated.The results show that the coating is relative thin when the nitrogen flux is small and mainly consists of Ti2N,α-Ti,Ti O and TiN phases,and the metastable phase of Ti2N is developed due to the rapid solidification of ESD.While in excessive nitrogen flux condition,many micro-cracks and holes might be generated in the coating.In moderate nitrogen flux,the coating is mainly composed of TiN phase,and is dense and uniform（50-55 μm）.The average hardness is HV0.2 1165.2,which is 3.4 times that of the TC11 substrate.The TiN coatings prepared in moderate nitrogen flux perform the best wear resistance.The wear loss of the coating is 0.4 mg,which is 2/9 that of the TC11 substrate.The main wear mechanisms of the coatings are micro-cutting wear accompanied by multi-plastic deformation wear.
基金Project(2010CB731705)supported by the National Basic Research Program of China
文摘Cyclic thermal exposure tests of infrared heating to 800 ℃ in 120 s followed by compressed air cooling to 150 ℃ in 60 s were performed for the laser deposited Ti60A （Ti5.54Al3.38Sn3.34Zr0.37Mo0.46Si） alloy. The effects of thermal exposure cycles on length ofβphase, area fraction ofαphase and microhardness of alloy were examined by OM, SEM and EDS. The results indicate that thermal exposure cycles have significant effects on length ofβphase, area fraction ofαphase and microhardness of the alloy. The original fine basket-weaveβand 78.5%αtransform to transient wedge-likeβ, finally leaving granularβand 97.6%coarsenedαwith the increased thermal exposure cycles. The formation mechanism of coarsenedαand broken-upβmicrostructure is discussed. The alloy after 750 thermal exposure cycles has the maximum microhardness, 33.3%higher than that of the as-deposited alloy.
基金Project(20110933K) supported by the State Key Laboratory of Powder Metallurgy,ChinaProject(2012QNZT002) supported by the Freedom Explore Program of Central South University,ChinaProject(CSUZC2012024) supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University,China
文摘A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibrium shape was deposited on Cu substrates by hot-filament chemical vapor deposition（HF-CVD）,and the sp2 carbon content was less than 5.56%.The nucleation and growth of diamond film were investigated by micro-Raman spectroscopy,scanning electron microscopy,and X-ray diffraction.The results show that the nucleation density of diamond on the Ni-modified Cu substrates is 10 times higher than that on blank Cu substrates.The enhancement mechanism of the nucleation kinetics by Ni modification layer results from two effects：namely,the nanometer rough Ni-modified surface shows an improved absorption of nanodiamond particles that act as starting points for the diamond nucleation during HF-CVD process;the strong catalytic effect of the Ni-modified surface causes the formation of graphite layer that acts as an intermediate to facilitate diamond nucleation quickly.
文摘The effects of carbon content (0.078-0.100 wt.%) on the microstructure and properties of 1000 MPa grade deposited metal produced by gas metal arc welding have been investigated. Experimental results show that the microstructure of the deposited metal was mainly composed of martensite, bainite and retained austenite. With increasing carbon content, the proportion of martensite increased, and the amount of bainite was reduced. High carbon content is beneficial to strength, but harmful to impact toughness, and thus, carbon reductions lead to the increase in impact toughness. When the carbon content was 0.100 wt.%, the lowest Charpy absorbed energy of 47 J at — 40℃ for the deposited metal was achieved, the highest yield strength of 1038 MPa was attained, and the yield-to-tensile ratio was more than 0.88, while the highest Charpy absorbed energy of 55.7 J at — 40℃ and the lowest yield strength of 915 MPa were obtained when the deposited metal contains 0.078 wt.% C, and the yield-to-tensile ratio was less than 0.85. It is concluded that bainite fraction and fine effective grain size were the dominant factors to achieve good comprehensive mechanical properties (the required strength and an acceptable toughness) of deposited metals with various carbon contents.
基金Item Sponsored by International Science and Technology Cooperation Program of China(2015DFA51460)
文摘Alloy element and microstructure are key factors that dominate mechanical and corrosion resistant properties of weathering steel. The effect of Mo on microstructure, mechanical properties and corrosion resistant property of depos ited metal was investigated. Experimental results show that with the increase of Mo content in deposited metals, the phase transformation temperature decreases, and the ferrite zone in CCT diagram moves rightward, resulting in en larged bainite zone and reduced ferrite and pearlite zone. The addition of 0.24 mass% Mo in deposited metal results in the increase of tensile strength, more M-A constituent and less high angle grain which reduce the low temperature toughness. It is found that Mo can raise the weathering resistance of deposited metal in industrial atmosphere. Analy sis indicates that Mo may enrich in the inner rust layer, produce MoO3, enhance the formation of compact rust film and impede the anode dissolution reaction. Granular bainite in deposited metals displays better corrosion resistance than acicular ferrite during the initial corrosion stage, but its long-term influence on the corrosion resistance is limited.
文摘We report a case of sigmoid colonic carcinoma associated with deposited ova of Schistosoma japonicum. A 57-year old woman presented with a 10-mo history of left lower quadrant abdominal pain and a 2-mo history of bloody stools. She had a significant past medical history of asymptomatic schistosomiasis japonica and constipation. A colonoscopy showed an exophytic fragile neoplasm with an ulcerating surface in the sigmoid colon. During the radical operative procedure, we noted the partially encircling tumor was located in the distal sigmoid colon, and extended into the serosa. Succedent pathological analysis demonstrated the diagnosis of sigmoid colonic ulcerative tubular adenocarcinoma, and showed deposited ova of Schistosoma japonicum in both tumor lesions and mesenteric lymph nodes. Three days after surgery the patient returned to the normal bowel function with one defecation per day. These findings reveal that deposited schistosome ova play a possible role in the carcinogenesis of colorectal cancer.
文摘Organosilicone thin films have been deposited by plasma polymerization(pp)in a plasma enhanced chemical vapor deposition(PECVD)system using hexamethyldisilazane(HMDSN:C_(6)H_(19)Si_(2)N)as a monomer precursor,at different biases of the stainless-steel substrate holder.The substrate bias affected film thickness,surface morphology,chemical composition and photoluminescence(PL)emission.For a negatively biased substrate,it is found that the film thickness is the minimum,while the porosity and PL emission are the maximum.For a positively biased substrate,the thickness and the ratio of Si/N are the maximum which correspond to a blue shift of the PL emission in comparison with the case of non-biased grounded substrate.In addition,the characterization of the plasma using a single cylindrical Langmuir probe has been performed to obtain information about both the electron density and the positive ion energy,where it can be concluded that the ion energy plays a major role in determining film thickness.
基金Supported by the Youth Science Foundation of Shanxi Province under Grant No 2013021010-3the National Natural Science Foundation of China under Grant Nos 61434002 and 11404202
文摘Effect of mechanical stress on magnetic properties of an exchange-biased ferromagnetic/antiferromagnetic bilayer deposited on a flexible substrate is investigated. The hysteresis loops with different magnitudes and orientations of the stress can be classified into three types. The corresponding physical conditions for each type of the loop are deduced based on the principle of minimal energy. The equation of the critical stress is derived, which can judge whether the loops show hysteresis or not. Numerical calculations suggest that except for the magnitude of the mechanical stress, the relative orientation of the stress is also an important factor to tune the exchange bias effect.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.2009B13514)the Doctoral Fund of the Ministry of Education of China(Grant No.20100094110002)
文摘In order to study deposited sediment settlement and consolidation mechanisms, sediment settlement experiments were conducted using a settlement column. Based on the experimental results, sediment settlement stage definition, excessive pore pressure （EPP） dissipation, and consolidation constitutive equations are discussed. Three stages, including the free settlement, hindered settlement, and self-weight consolidation settlement stages, are defined. The results of this study show that sediment settlement is mainly affected by the initial sediment concentration and initial settlement height, and the interface settlement rate is linearly attenuated with time on bilogarithmic scales during the hindered settlement and self-weight consolidation settlement stages. Moreover, the deposited sediment layer in the self-weight consolidation settlement stage experiences large strains, and the settlement amount in this stage is about 32% to 59% of the initial height of deposited sediment. EPP is nonlinearly distributed in the settlement direction, and consolidation settlement is faster than EPP dissipation in the self-weight consolidation settlement stage. Consolidation constitutive equations for the hydraulic conductivity and effective stress, applicable to large-strain consolidation calculation, were also determined and fitted in the power function form.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11174142 and 11304160he National Basic Research Program of China under Grant No 2012CB921504the Special Fund for Public Interest of China under Grant No201510068
文摘La-doped and undoped xBiIn03-（1 - x）PbTi03 （BI-PT） thin films are deposited on （101）SrRuO3/（lOO）Pt/（lO0） MgO substrates by the rf-magnetron sputtering method. The structures of the films are characterized by XRD and SEM, and the results indicate that the thin films are grown with mainly （100） oriented and columnar structures. The ferroelectricity and piezoelectricity of the BI-PT films are also measured, and the measured results illustrate that both performances are effectively improved by the La-doping with suitable concentrations. These results will open up wide potential applications of the films in electronic devices.
基金This project is supported by National Natural Science Foundation of China （ Grant No. 51305178） Xuzhou City Science and Technology Plan Projects （Grant No. XC12A013）.
文摘In order to reduce sulphur （ S ） and phosphorus （ P ） impurities in deposited metal, a small amount of rare earth （RE） lanthanum （ La） and yttrium （Y） were added into the coating ofE4303 electrode, a low carbon steel electrode. The microstructures of deposited metal were analyzed with metalloscope, and then the content of S and P was examined by energy dispenive X-ray spectrometer （ EDXS ）, and by wavelength dispersive X-ray fluorescence （XRF） spectrometer for further examination. The results show that the proper addition of La and Y can be beneficial to the desulfurization and dephosphorization of the deposited metal. Certainly, difference in the addition amount of La and Y could lead to various desulfurization and dephosphorization efficiency, in which the former is more obvious than the latter. With the proper amount of La attd Y, there is finer microstructure in deposited metal, and mechanical properties are improved as well. The S content in deposited metal with added La and Y decreases by 44. 44 wt. % , while the P content 6. 67 wt. %, compared with that in deposited metal without La and II.
