A multistage solution treatment process was applied for nickel-based single crystal superalloys,complemented by various aging durations and cooling rates.The microstructure was characterized by scanning electron micro...A multistage solution treatment process was applied for nickel-based single crystal superalloys,complemented by various aging durations and cooling rates.The microstructure was characterized by scanning electron microscopy(SEM)to observe the γ'phase.Additionally,phase field simulations were conducted to model the growth ofγ'precipitates during aging and analyze their morphological evolution.The experimental results demonstrated that the multistage solution treatment effectively eliminated eutectic phases and carbides.Moreover,samples aged for 10 min exhibited larger and more rectangularγ'precipitates compared with those aged for 5 min.Notably,secondary γ'precipitates were observed in samples subjected to water cooling.Two indices for quantifying rectangularization were proposed and successfully applied.Based on the simulation results,lattice mismatch induced coherency stresses and elevated stress triaxiality along the <111> direction contributed to the rectangularization of theγ'phase.展开更多
Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the o...Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.展开更多
In secondary Al-Si based alloys,microalloying with Mn and Cr can modify harmful platelet-type Alx Fey Siz intermetallic phases to less detrimentalα-Alx(Fe,Mn,Cr)_(y)Siz phase(script or polygonal morphologies).However...In secondary Al-Si based alloys,microalloying with Mn and Cr can modify harmful platelet-type Alx Fey Siz intermetallic phases to less detrimentalα-Alx(Fe,Mn,Cr)_(y)Siz phase(script or polygonal morphologies).However,theα-Alx(Fe,Mn,Cr)_(y)Siz phase morphology,phase composition and the addition of Fecorrecting elements can be influenced by solidification conditions.Therefore,this research is aimed to highlight the morphological evolution and mechanisms ofα-Alx(Fe,Mn,Cr)_(y)Si_(z)phase in a Cr added Al-9%Si-1%Fe-0.2%Cr(all weight percentage thereafter,unless otherwise stated)alloy with varying Mn concentrations(0.25%,0.5%,and 0.8%).Microstructure evolution of Fe intermetallic phases is investi-gated under different casting conditions using a wedge-shaped die,Cu-chill block and melt quenching experiments.Thermodynamic simulations have been performed using CALculation of PHAse Diagrams(CALPHAD)method and compared with the experimental results for phase composition and formation temperatures ofα-Alx(Fe,Mn,Cr)_(y)Siz phase.The results indicated that for 0.25Mn-0.2Cr addition to Al-9Si-1Fe alloy,compact morphology containing polygonal phases are formed in Cu-chill casting,while the wedge castings predominantly show a mixed structure with platelets and script type morphologies.Tensile tests revealed a higher elongation value of 6.6%for mixed structure with platelet and script phases,which is decreased to 4.2%for polygonal phases in Al-9Si-1Fe-0.2Cr-0.25Mn alloy.This study highlights the importance of solidification conditions on morphologies of Fe-intermetallic phases and the mechanical properties by comparing selected literature relevant to high pressure die-casting process.展开更多
This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechani...This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechanical properties of Al-Mg-Mn-Fe-Cu alloys.The findings reveal that the microstructures of the alloys consisted of an Al matrix,Al_(6)(FeMn),and Al_(2)CuMg phase particles.The addition of Fe significantly increased the yield strength(YS),and ultimate tensile strength(UTS)of the alloys,while reducing elongation.The transformation of the 3D morphology of the Al_(6)(FeMn)phase from separated and fine particles with Chinese-script morphology to interconnected rod-like structure as Fe content increased from 0.1%to 0.8%.This strengthening effect was attributed to the slip lines being blocked at the vicinity of the inter-connected Fe-rich phase,leading to grain rotation and dislocation density increment around the Fe-rich phase,ultimately improving the strength of the alloys.However,the Fe-rich phases and Al_(2)CuMg phases were found to be prone to cracking under tensile stress,resulting in decreased elongation of the alloys.This study provides a potential application in the design and manufacturing of new non-heat-treatable Al alloys for the automotive industry.展开更多
A series of optically active copolymers with various feed ratios have been synthesized through helix-sense-selective copolymerization catalyzed by[Rh(norbornadiene)Cl]2-triethylamine.This process involves two proline-...A series of optically active copolymers with various feed ratios have been synthesized through helix-sense-selective copolymerization catalyzed by[Rh(norbornadiene)Cl]2-triethylamine.This process involves two proline-derived acetylene monomers,(S)-N-(4-chlorophenyl)carbamoyl-2-ethynyl pyrrolidine(MCl)and(S)-N-(tert-butoxycarbonyl)-2-ethynyl pyrrolidine,followed by acidic deprotection and neutralization.These copolymers adopt helical conformations with a preferred handedness,as demonstrated by nuclear magnetic resonance spectroscopy and a series of spectroscopic analyses.The chiroptical activity intensity of copolymer has been found to increase with MCl content.Consequently,the enantioseparation capabilities of copolymers containing 95 mol%,90 mol%,and 85 mol%MCl units have been assessed as chiral stationary phases in high-performance liquid chromatography because of their good chiroptical activities.These chiral stationary phases effectively enantioseparate racemic alcohols,sulfoxides,amides,and metal complexes.Notably,the copolymer with 90 mol%MCl shows superior chiral recognition ability,especially for 1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethanol(α=1.19)and 4-methylbenzenesulfinamide(α=1.47).Insights from molecular dynamic simulation and autodock analysis indicate that hydrogen bonding andπ-πstacking interactions between the chiral stationary phases and enantiomers play a key role for successful chiral separation.Our contribution not only demonstrates the importance of hydrogen bonding donor and copolymer chiroptical activity of chiral stationary phases for chiral resolution,but will also provide valuable insights for the future development of novel stationary phases.展开更多
Microstructural characterization,mass loss tests,hydrogen evolution tests,electrochemical measurements,and corrosion morphology observations were conducted to investigate the effect of the secondary phases on the corr...Microstructural characterization,mass loss tests,hydrogen evolution tests,electrochemical measurements,and corrosion morphology observations were conducted to investigate the effect of the secondary phases on the corrosion behavior of the as-cast Mg−7Sn−1Zn−1Y(TZW711)alloy after solution treatment(T4)and aging treatment(T6).The results show that the T4-TZW711 alloy possesses the highest corrosion resistance in the early corrosion stage.This is because the dissolution of Mg2Sn reduces the cathodic current density and increases the charge transfer resistance(Rct).When the corrosion time is prolonged,the undissolved and clustered MgSnY phase will peel off from the T4-TZW711 alloy surface,thereby increasing the corrosion rate of the alloy.After aging treatment,the undissolved MgSnY phase is dispersed,which results in a lower localized corrosion sensitivity of T6-TZW711 alloy than that of the T4-TZW711 alloy,suggesting that the T6 treatment can enhance the corrosion resistance of Mg−7Sn−1Zn−1Y alloys.展开更多
Objective:To evaluate the effectiveness of surgical combination with traditional Chinese medicine dialectical therapy in three phases for the treatment of intertrochanteric fracture of the femur(IFF).Methods:84 patien...Objective:To evaluate the effectiveness of surgical combination with traditional Chinese medicine dialectical therapy in three phases for the treatment of intertrochanteric fracture of the femur(IFF).Methods:84 patients with IFF admitted to the hospital from December 2022 to December 2024 were selected and randomly divided into two groups using a random number table.The combined group received surgery and traditional Chinese medicine dialectical therapy in three phases,while the control group received surgery alone.The total effective rate,fracture healing time,hip function score,and lower extremity function score were compared between the two groups.Results:The total effective rate was higher in the combined group than in the control group(P<0.05).After treatment,the fracture healing time was shorter in the combined group than in the control group,and the hip function and lower extremity function scores were higher in the combined group than in the control group(P<0.05).Conclusion:Surgical combination with traditional Chinese medicine dialectical therapy in three phases can shorten the fracture healing time of IFF patients and restore their hip and lower extremity function,demonstrating significant efficacy.展开更多
Flood disasters can have a serious impact on people's production and lives, and can cause hugelosses in lives and property security. Based on multi-source remote sensing data, this study establisheddecision tree c...Flood disasters can have a serious impact on people's production and lives, and can cause hugelosses in lives and property security. Based on multi-source remote sensing data, this study establisheddecision tree classification rules through multi-source and multi-temporal feature fusion, classified groundobjects before the disaster and extracted flood information in the disaster area based on optical imagesduring the disaster, so as to achieve rapid acquisition of the disaster situation of each disaster bearing object.In the case of Qianliang Lake, which suffered from flooding in 2020, the results show that decision treeclassification algorithms based on multi-temporal features can effectively integrate multi-temporal and multispectralinformation to overcome the shortcomings of single-temporal image classification and achieveground-truth object classification.展开更多
Landslide susceptibility map(LSM)is a crucial tool for managing landslide hazards and identifying potential landslide areas.However,current LSMs rely primarily on static landslide-related factors with little variation...Landslide susceptibility map(LSM)is a crucial tool for managing landslide hazards and identifying potential landslide areas.However,current LSMs rely primarily on static landslide-related factors with little variation over several decades,thereby overlooking the movement of slopes and failing to capture landslide dynamics.The long-term ground deformation map(GDM)derived from multi-temporal interferometric synthetic aperture radar(MT-InSAR)can effectively address the shortcomings.Fengjie County is an important area for geohazard management in the Three Gorges Reservoir Area(TGRA),China.Landslides in this area,however,cause significant socio-economic loss due to geological,tectonic,climatic,and anthropological factors.This research aims to integrate random forest(RF)with MT-InSAR to generate a landslide dynamic susceptibility map(LDSM)for Fengjie County,enhancing the reliability of landslide risk management.First,the RF model was employed to generate a static LSM,whereas MT-InSAR was utilized to obtain the GDM of the study area from January 2020 to June 2023.The static LSM and the GDM were subsequently integrated using a dynamic weight matrix to derive the LDSM.Our analysis covered a temporal framework spanning three years,focusing on spatiotemporal changes in landslide susceptibility levels and the influence of climate factors.Compared with the static LSM,the LDSM can promptly identify moving landslide areas,reduce high landslide susceptibility areas,and achieve greater accuracy.Moreover,the spatiotemporal changes in landslide susceptibility are regulated by the total annual rainfall,with wet years being more conducive to landslides than dry years.The proposed LDSM offers useful insights for the dynamic prevention and refined management of landslide hazards in the TGRA,significantly enhancing the resilience in this region.展开更多
The precipitation of secondary Laves phases and its effect on notch sensitivity are systematically studied in Thermo-Span alloy. The results show that the precipitation peak temperature of secondary Laves phases is 9...The precipitation of secondary Laves phases and its effect on notch sensitivity are systematically studied in Thermo-Span alloy. The results show that the precipitation peak temperature of secondary Laves phases is 925 ℃. Below 925 ℃, the volume fraction of secondary Laves phases increases with the rise of the temperature, and its morphology changes from granular to thin-film;above 925 ℃, the volume fraction of secondary Laves phases shows an opposite trend to temperature, and its morphology changes from thin-film to granular. A detailed explanation through linear density (ρ) is provided that the influence of secondary Laves phases at the grain boundaries (GBs) on notch sensitivity depends on the coupling competition effect of their size, quantity, and morphology. Notably, the granular Laves phases are more beneficial to improving the notch sensitivity of the alloy compared with thin-film Laves phases. Granular secondary Laves phases can promote the formation of γ′ phases depletion zone to improve the ability of GBs to accommodate high strain localization, and effectively inhibit the crack initiation and propagation.展开更多
In the energy industry landscape,thermal power generation stands as a critical energy supply method,and the safety of its construction and operation is paramount.Currently,all stages of the life cycle of construction ...In the energy industry landscape,thermal power generation stands as a critical energy supply method,and the safety of its construction and operation is paramount.Currently,all stages of the life cycle of construction projects have garnered widespread attention.Among these,the infrastructure construction and operation phases of thermal power generation enterprises pose numerous issues worthy of in-depth study in terms of safety production management.This article starts by examining safety production management during these two phases,analyzing characteristics such as management models,legal bases,and responsible entities.It explores the reasons behind these characteristics and elaborates on key management priorities,providing a comprehensive and insightful reference for safety production management in thermal power generation enterprises.展开更多
1.Introduction Compared with the widely used vapor-compression refrigeration,solid-state cooling based on phase transition offers higher ef-ficiency,environmental friendliness,and smaller volume[1,2].The phase transit...1.Introduction Compared with the widely used vapor-compression refrigeration,solid-state cooling based on phase transition offers higher ef-ficiency,environmental friendliness,and smaller volume[1,2].The phase transition of solid refrigerants can be triggered by external fields,i.e.,magnetic fields[3-5],electric fields[6,7].展开更多
In-situ tensile tests were conducted on a chemically corroded third-generation single-crystal superalloy DD9 at 980 and 1100℃.The phase transformation in the surface areas during the tensile process was analyzed usin...In-situ tensile tests were conducted on a chemically corroded third-generation single-crystal superalloy DD9 at 980 and 1100℃.The phase transformation in the surface areas during the tensile process was analyzed using field emission scanning electron microscope,energy dispersive X-ray spectroscope,electron probe X-ray microanalysis,and transmission electron microscope.The phase transformation mechanism on the surface and the influence mechanism were studied through observation and dynamic calculation.During tensile tests at elevated temperatures,chemical corrosion promotes the precipitation of topologically close-packed(tcp)μphase andσphase on the alloy surface.Both the precipitation amount and size of these two phases on the surface at 1100℃are greater than those at 980℃.The precipitation of tcp phase on the alloy surface results in the formation of an influence layer on the surface area,and the distribution characteristics of alloying elements are significantly different from those of the substrate.The depth of the influence layer at 1100℃is greater than that at 980℃.The precipitation of tcp phase prompts the phase transition fromγphase toγ′phase around the tcp phase.展开更多
We theoretically investigate a one-dimensional Su–Schrieffer–Heeger(SSH)model with spin–orbit coupling(SOC)and sublattice-dependent gain and loss.As the gain and loss increase,the system transitions from a parity-t...We theoretically investigate a one-dimensional Su–Schrieffer–Heeger(SSH)model with spin–orbit coupling(SOC)and sublattice-dependent gain and loss.As the gain and loss increase,the system transitions from a parity-time(PT)symmetric phase to a parity-time and anti-parity-time(PT&APT)symmetry-breaking phase,and finally to an anti-paritytime(APT)symmetric phase.Notably,when the intracell and intercell hopping,intracell and intercell SOC parameters are all equal to half the gain–loss parameter,the model exhibits a doubly degenerate exceptional point(EP).When the SOC is equal for intracell and intercell interactions,a stronger hopping mechanism within cells compared to that between cells results in an increase in SOC that transitions the Zak phase from zero to a non-quantized value,eventually arriving at one.In contrast,a reduction in the strength of intracell hopping leads the Zak phase to transition from two to a non-quantized value,eventually arriving at one.If the intracell and intercell SOC are not aligned,altering these couplings leads to a shift in the Zak phase from two to a non-quantized level,then to one,re-entering the non-quantized region,and eventually arriving at zero.We suggest a practical experimental setup for our model that can be implemented using electrical circuits.展开更多
The addition of Ce significantly enhances cleanliness of steel and modifies precipitation phases.However,there are differences in the effects of different alloy systems,especially its role in M54 steel is insufficient...The addition of Ce significantly enhances cleanliness of steel and modifies precipitation phases.However,there are differences in the effects of different alloy systems,especially its role in M54 steel is insufficiently understood.This study investigates the evolution of inclusions and precipitation phases in M54 steel ingots with varying Ce additions.Results indicate that the addition of Ce reduces the content of impurity elements(O and S)and transforms Mg and Al inclusions into Ce inclusions,which is due to the stronger affinity between Ce and impurity elements such as O and S.Ce inclusions serve as nucleation sites for dendrites,reducing secondary dendrite arm spacing.In addition,these inclusions and Cecontaining precipitated phase also act as nucleation sites for carbide precipitates,effectively refining their distribution by reducing growth spaces and increasing nucleation density.Notably,as Ce content increases from 0 to 0.01 wt%,the precipitation phase content decreases significantly but rises slightly with further increases in Ce content due to the formation of additional Ce-containing precipitates.By quantitatively comparing the dendrite arm spacing,cleanliness,content and size of precipitated phase,it is determined that the optimum addition amount of Ce for M54 steel is about 0.01 wt%.展开更多
Based on α→α2+γ phase transition and crystallographic orientation relationship,as well as the the-ory of grain-preferred growth under high magnetic fields,this study proposes a novel method to adjust the alignment...Based on α→α2+γ phase transition and crystallographic orientation relationship,as well as the the-ory of grain-preferred growth under high magnetic fields,this study proposes a novel method to adjust the alignment ofα2/γlamellae for TiAl alloys through two-step treatment.The first step involved the pretreatment at 1350℃(αsingle-phase region),followed by high magnetic field heat treatment at the same temperature.Results show that the fraction of α2/γ lamellar orientation with an angle<30°re-specting the magnetic field direction increases significantly to 72.74%for pretreated Ti-42.91Al-0.69Fe alloy after holding for 30 min at 1350℃ with the 10 T magnetic field,compared with the reference sample.The preferred distribution of α2/γ lamellae is attributed to the magnetic driving force generated atαgrain boundaries,which predominantly dominates the preferential growth behavior ofαgrains by influencing the grain boundary migration during the short isothermal time under the 10 T magnetic field.After holding for 5 h at 1350℃,the average grain size of Ti-42.91Al-0.69Fe alloy increases,and the grain boundaries become flatter.Consequently,the curvature driving force generated at theαgrain boundaries is mostly lower than the magnetic driving force.The direction of grain boundary migration is thus pri-marily determined by the direction of magnetic driving forces during the holding time at 1350℃ under the 10 T magnetic field.Specifically,the grain boundaries ofαgrain move towards adjacentαgrains and are swallowed up to grow as the<0001>orientation ofαgrains is normal to the magnetic field direction.Due to the unique habitus plane ofγandαphases,the α2/γ lamellar orientation is approximately par-allel to the magnetic field direction in the subsequent cooling progress.These results indicate that high magnetic field heat treatment atαsingle-phase region can adjust the alignment of α2/γ lamellae.展开更多
For chromatographic separation,the reasonable modulation of stationary phases is the key factor to achieve high separation performance.We proposed that developing MOF stationary phases through precisely modulating the...For chromatographic separation,the reasonable modulation of stationary phases is the key factor to achieve high separation performance.We proposed that developing MOF stationary phases through precisely modulating the thermodynamic interactions between MOFs and analytes is conducive to improving the separation resolution.MIL-125,MIL-125-NH_(2),MIL-143-BTB,and MIL-143-TATB were developed as stationary phases with the careful modulation of organic ligands.MIL-125-NH_(2)and MIL-143-TATB coated columns exhibited much better separation performance than their counterparts,MIL-125 and MIL-143-BTB,respectively.The investigation of the separation mechanism indicated that thermodynamic interaction,rather than kinetic diffusion,was responsible for the separation improvement.MIL-125-NH_(2)and MIL-143-TATB provided stronger and distinguishable interactions with targets than corresponding MIL-125 and MIL-143-BTB,respectively,resulting in enhanced separation performance.This work demonstrates a guide to improving the separation performance of MOF stationary phases by increasing the thermodynamic interactions between MOFs and analytes.展开更多
A mathematical model coupling flow,solidification,strain-stress,and interface failure was developed.Following identification of crack source type through thermal tensile experiment and validation by strain-stress comp...A mathematical model coupling flow,solidification,strain-stress,and interface failure was developed.Following identification of crack source type through thermal tensile experiment and validation by strain-stress comparison,the model was used to investigate slab cracking tendency near precipitated phases,considering various locations,sizes and shapes of them.The results show that the jet from submerged entry nozzle creates a“double roll”flow pattern during continuous casting,resulting in more uniform temperature distributions at slab corner and wide surface center compared with narrow surface center.Consequently,precipitated phases,particularly those located on the narrow surface,readily induce stress concentration and thus increase cracking tendency.A smaller precipitated phase size can reduce the stress concentration zone,while a more spherical shape can distribute surrounding stress along its surface and lower the internal stress within it,thereby decreasing the risk of slab cracking during continuous casting.The optimal precipitated phase exhibits a spherical or ellipsoidal shape with a major axis of less than 5µm,minimizing its potential to initiate cracks.展开更多
基金supported by the Stable Support Project and the Major National Science and Technology Project,China(Nos.2017-Ⅶ-0008-0101,2017-Ⅵ-0003-0073)。
文摘A multistage solution treatment process was applied for nickel-based single crystal superalloys,complemented by various aging durations and cooling rates.The microstructure was characterized by scanning electron microscopy(SEM)to observe the γ'phase.Additionally,phase field simulations were conducted to model the growth ofγ'precipitates during aging and analyze their morphological evolution.The experimental results demonstrated that the multistage solution treatment effectively eliminated eutectic phases and carbides.Moreover,samples aged for 10 min exhibited larger and more rectangularγ'precipitates compared with those aged for 5 min.Notably,secondary γ'precipitates were observed in samples subjected to water cooling.Two indices for quantifying rectangularization were proposed and successfully applied.Based on the simulation results,lattice mismatch induced coherency stresses and elevated stress triaxiality along the <111> direction contributed to the rectangularization of theγ'phase.
基金supported by the National Natural Science Foundation of China(No.22276219)the foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)+1 种基金the major program Natural Science Foundation of Hunan Province of China(No.2021JC0001)the Fundamental Research Funds for the Central Universities of Central South University(No.2024ZZTS0063).
文摘Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.
基金supported by the U.S.Department of Energy’s Office of Energy Efficiency and Renewable Energy(EERE)under the Advanced Manufacturing Office Award Number DE-EE0007897。
文摘In secondary Al-Si based alloys,microalloying with Mn and Cr can modify harmful platelet-type Alx Fey Siz intermetallic phases to less detrimentalα-Alx(Fe,Mn,Cr)_(y)Siz phase(script or polygonal morphologies).However,theα-Alx(Fe,Mn,Cr)_(y)Siz phase morphology,phase composition and the addition of Fecorrecting elements can be influenced by solidification conditions.Therefore,this research is aimed to highlight the morphological evolution and mechanisms ofα-Alx(Fe,Mn,Cr)_(y)Si_(z)phase in a Cr added Al-9%Si-1%Fe-0.2%Cr(all weight percentage thereafter,unless otherwise stated)alloy with varying Mn concentrations(0.25%,0.5%,and 0.8%).Microstructure evolution of Fe intermetallic phases is investi-gated under different casting conditions using a wedge-shaped die,Cu-chill block and melt quenching experiments.Thermodynamic simulations have been performed using CALculation of PHAse Diagrams(CALPHAD)method and compared with the experimental results for phase composition and formation temperatures ofα-Alx(Fe,Mn,Cr)_(y)Siz phase.The results indicated that for 0.25Mn-0.2Cr addition to Al-9Si-1Fe alloy,compact morphology containing polygonal phases are formed in Cu-chill casting,while the wedge castings predominantly show a mixed structure with platelets and script type morphologies.Tensile tests revealed a higher elongation value of 6.6%for mixed structure with platelet and script phases,which is decreased to 4.2%for polygonal phases in Al-9Si-1Fe-0.2Cr-0.25Mn alloy.This study highlights the importance of solidification conditions on morphologies of Fe-intermetallic phases and the mechanical properties by comparing selected literature relevant to high pressure die-casting process.
基金support from the Natural Science Foundation of China(Nos.52104373,52074131,and 51974092)the Basic and Applied Basic Foundation of Guangdong Province(No.2020B1515120065)。
文摘This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechanical properties of Al-Mg-Mn-Fe-Cu alloys.The findings reveal that the microstructures of the alloys consisted of an Al matrix,Al_(6)(FeMn),and Al_(2)CuMg phase particles.The addition of Fe significantly increased the yield strength(YS),and ultimate tensile strength(UTS)of the alloys,while reducing elongation.The transformation of the 3D morphology of the Al_(6)(FeMn)phase from separated and fine particles with Chinese-script morphology to interconnected rod-like structure as Fe content increased from 0.1%to 0.8%.This strengthening effect was attributed to the slip lines being blocked at the vicinity of the inter-connected Fe-rich phase,leading to grain rotation and dislocation density increment around the Fe-rich phase,ultimately improving the strength of the alloys.However,the Fe-rich phases and Al_(2)CuMg phases were found to be prone to cracking under tensile stress,resulting in decreased elongation of the alloys.This study provides a potential application in the design and manufacturing of new non-heat-treatable Al alloys for the automotive industry.
基金supported by the National Natural Science Foundation of China(Nos.52273002 and 52333008)the funding of Boya Postdoctoral Fellowship at Peking University,BMS Junior Fellow Program and the National Funding Program for Postdoctoral Researchers(No.GZC20230031).
文摘A series of optically active copolymers with various feed ratios have been synthesized through helix-sense-selective copolymerization catalyzed by[Rh(norbornadiene)Cl]2-triethylamine.This process involves two proline-derived acetylene monomers,(S)-N-(4-chlorophenyl)carbamoyl-2-ethynyl pyrrolidine(MCl)and(S)-N-(tert-butoxycarbonyl)-2-ethynyl pyrrolidine,followed by acidic deprotection and neutralization.These copolymers adopt helical conformations with a preferred handedness,as demonstrated by nuclear magnetic resonance spectroscopy and a series of spectroscopic analyses.The chiroptical activity intensity of copolymer has been found to increase with MCl content.Consequently,the enantioseparation capabilities of copolymers containing 95 mol%,90 mol%,and 85 mol%MCl units have been assessed as chiral stationary phases in high-performance liquid chromatography because of their good chiroptical activities.These chiral stationary phases effectively enantioseparate racemic alcohols,sulfoxides,amides,and metal complexes.Notably,the copolymer with 90 mol%MCl shows superior chiral recognition ability,especially for 1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethanol(α=1.19)and 4-methylbenzenesulfinamide(α=1.47).Insights from molecular dynamic simulation and autodock analysis indicate that hydrogen bonding andπ-πstacking interactions between the chiral stationary phases and enantiomers play a key role for successful chiral separation.Our contribution not only demonstrates the importance of hydrogen bonding donor and copolymer chiroptical activity of chiral stationary phases for chiral resolution,but will also provide valuable insights for the future development of novel stationary phases.
基金National Natural Science Foundation of China(Nos.52301041,52022017,52065009,52371005)Special Fund for Special Posts of Guizhou University,China(No.[2023]26)+1 种基金Science and Technology Planning Project of Guizhou Province,China(No.ZK2021269)Fundamental Research Funds for the Central Universities,China(No.DUT23YG104)。
文摘Microstructural characterization,mass loss tests,hydrogen evolution tests,electrochemical measurements,and corrosion morphology observations were conducted to investigate the effect of the secondary phases on the corrosion behavior of the as-cast Mg−7Sn−1Zn−1Y(TZW711)alloy after solution treatment(T4)and aging treatment(T6).The results show that the T4-TZW711 alloy possesses the highest corrosion resistance in the early corrosion stage.This is because the dissolution of Mg2Sn reduces the cathodic current density and increases the charge transfer resistance(Rct).When the corrosion time is prolonged,the undissolved and clustered MgSnY phase will peel off from the T4-TZW711 alloy surface,thereby increasing the corrosion rate of the alloy.After aging treatment,the undissolved MgSnY phase is dispersed,which results in a lower localized corrosion sensitivity of T6-TZW711 alloy than that of the T4-TZW711 alloy,suggesting that the T6 treatment can enhance the corrosion resistance of Mg−7Sn−1Zn−1Y alloys.
文摘Objective:To evaluate the effectiveness of surgical combination with traditional Chinese medicine dialectical therapy in three phases for the treatment of intertrochanteric fracture of the femur(IFF).Methods:84 patients with IFF admitted to the hospital from December 2022 to December 2024 were selected and randomly divided into two groups using a random number table.The combined group received surgery and traditional Chinese medicine dialectical therapy in three phases,while the control group received surgery alone.The total effective rate,fracture healing time,hip function score,and lower extremity function score were compared between the two groups.Results:The total effective rate was higher in the combined group than in the control group(P<0.05).After treatment,the fracture healing time was shorter in the combined group than in the control group,and the hip function and lower extremity function scores were higher in the combined group than in the control group(P<0.05).Conclusion:Surgical combination with traditional Chinese medicine dialectical therapy in three phases can shorten the fracture healing time of IFF patients and restore their hip and lower extremity function,demonstrating significant efficacy.
文摘Flood disasters can have a serious impact on people's production and lives, and can cause hugelosses in lives and property security. Based on multi-source remote sensing data, this study establisheddecision tree classification rules through multi-source and multi-temporal feature fusion, classified groundobjects before the disaster and extracted flood information in the disaster area based on optical imagesduring the disaster, so as to achieve rapid acquisition of the disaster situation of each disaster bearing object.In the case of Qianliang Lake, which suffered from flooding in 2020, the results show that decision treeclassification algorithms based on multi-temporal features can effectively integrate multi-temporal and multispectralinformation to overcome the shortcomings of single-temporal image classification and achieveground-truth object classification.
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.42225702)the Maria Skłodowska-Curie Action(MSCA)-UPGRADE(mUltiscale IoT equipPed lonG linear infRastructure resilience built and sustAinable DevelopmEnt)project-HORIZON-MSCA-2022-SE-01(Grant No.101131146)。
文摘Landslide susceptibility map(LSM)is a crucial tool for managing landslide hazards and identifying potential landslide areas.However,current LSMs rely primarily on static landslide-related factors with little variation over several decades,thereby overlooking the movement of slopes and failing to capture landslide dynamics.The long-term ground deformation map(GDM)derived from multi-temporal interferometric synthetic aperture radar(MT-InSAR)can effectively address the shortcomings.Fengjie County is an important area for geohazard management in the Three Gorges Reservoir Area(TGRA),China.Landslides in this area,however,cause significant socio-economic loss due to geological,tectonic,climatic,and anthropological factors.This research aims to integrate random forest(RF)with MT-InSAR to generate a landslide dynamic susceptibility map(LDSM)for Fengjie County,enhancing the reliability of landslide risk management.First,the RF model was employed to generate a static LSM,whereas MT-InSAR was utilized to obtain the GDM of the study area from January 2020 to June 2023.The static LSM and the GDM were subsequently integrated using a dynamic weight matrix to derive the LDSM.Our analysis covered a temporal framework spanning three years,focusing on spatiotemporal changes in landslide susceptibility levels and the influence of climate factors.Compared with the static LSM,the LDSM can promptly identify moving landslide areas,reduce high landslide susceptibility areas,and achieve greater accuracy.Moreover,the spatiotemporal changes in landslide susceptibility are regulated by the total annual rainfall,with wet years being more conducive to landslides than dry years.The proposed LDSM offers useful insights for the dynamic prevention and refined management of landslide hazards in the TGRA,significantly enhancing the resilience in this region.
文摘The precipitation of secondary Laves phases and its effect on notch sensitivity are systematically studied in Thermo-Span alloy. The results show that the precipitation peak temperature of secondary Laves phases is 925 ℃. Below 925 ℃, the volume fraction of secondary Laves phases increases with the rise of the temperature, and its morphology changes from granular to thin-film;above 925 ℃, the volume fraction of secondary Laves phases shows an opposite trend to temperature, and its morphology changes from thin-film to granular. A detailed explanation through linear density (ρ) is provided that the influence of secondary Laves phases at the grain boundaries (GBs) on notch sensitivity depends on the coupling competition effect of their size, quantity, and morphology. Notably, the granular Laves phases are more beneficial to improving the notch sensitivity of the alloy compared with thin-film Laves phases. Granular secondary Laves phases can promote the formation of γ′ phases depletion zone to improve the ability of GBs to accommodate high strain localization, and effectively inhibit the crack initiation and propagation.
文摘In the energy industry landscape,thermal power generation stands as a critical energy supply method,and the safety of its construction and operation is paramount.Currently,all stages of the life cycle of construction projects have garnered widespread attention.Among these,the infrastructure construction and operation phases of thermal power generation enterprises pose numerous issues worthy of in-depth study in terms of safety production management.This article starts by examining safety production management during these two phases,analyzing characteristics such as management models,legal bases,and responsible entities.It explores the reasons behind these characteristics and elaborates on key management priorities,providing a comprehensive and insightful reference for safety production management in thermal power generation enterprises.
基金supported by the National Natural Science Foundation of China(Nos.52371106,52371025,52171154,51871076,52071118,and 52301223)Interdisciplinary Research Foundation of HIT(No.IR2021201)+4 种基金the Natural Science Foundation of Ningbo City(No.2023J346)supported by Zhejiang Provincial Natural Science Foundation of China(No.LQ24E010004)supported by the National Science Foundation(NSF)-Earth Sciences(No.EAR-1634415)the Department of Energy(DOE)-GeoSciences(No.DE-FG02-94ER14466)supported by DOE-BES(No.DE-AC02-06CH11357).
文摘1.Introduction Compared with the widely used vapor-compression refrigeration,solid-state cooling based on phase transition offers higher ef-ficiency,environmental friendliness,and smaller volume[1,2].The phase transition of solid refrigerants can be triggered by external fields,i.e.,magnetic fields[3-5],electric fields[6,7].
文摘In-situ tensile tests were conducted on a chemically corroded third-generation single-crystal superalloy DD9 at 980 and 1100℃.The phase transformation in the surface areas during the tensile process was analyzed using field emission scanning electron microscope,energy dispersive X-ray spectroscope,electron probe X-ray microanalysis,and transmission electron microscope.The phase transformation mechanism on the surface and the influence mechanism were studied through observation and dynamic calculation.During tensile tests at elevated temperatures,chemical corrosion promotes the precipitation of topologically close-packed(tcp)μphase andσphase on the alloy surface.Both the precipitation amount and size of these two phases on the surface at 1100℃are greater than those at 980℃.The precipitation of tcp phase on the alloy surface results in the formation of an influence layer on the surface area,and the distribution characteristics of alloying elements are significantly different from those of the substrate.The depth of the influence layer at 1100℃is greater than that at 980℃.The precipitation of tcp phase prompts the phase transition fromγphase toγ′phase around the tcp phase.
基金Project supported by the Natural Science Foundation of Chongqing,China(Grant No.CSTB2024NSCQ-MSX0736)Science and Technology Innovation Key R&D Program of Chongqing(Grant No.CSTB2024TIAD-STX0035)the Research Foundation of Institute for Advanced Sciences of CQUPT(Grant No.E011A2022328)。
文摘We theoretically investigate a one-dimensional Su–Schrieffer–Heeger(SSH)model with spin–orbit coupling(SOC)and sublattice-dependent gain and loss.As the gain and loss increase,the system transitions from a parity-time(PT)symmetric phase to a parity-time and anti-parity-time(PT&APT)symmetry-breaking phase,and finally to an anti-paritytime(APT)symmetric phase.Notably,when the intracell and intercell hopping,intracell and intercell SOC parameters are all equal to half the gain–loss parameter,the model exhibits a doubly degenerate exceptional point(EP).When the SOC is equal for intracell and intercell interactions,a stronger hopping mechanism within cells compared to that between cells results in an increase in SOC that transitions the Zak phase from zero to a non-quantized value,eventually arriving at one.In contrast,a reduction in the strength of intracell hopping leads the Zak phase to transition from two to a non-quantized value,eventually arriving at one.If the intracell and intercell SOC are not aligned,altering these couplings leads to a shift in the Zak phase from two to a non-quantized level,then to one,re-entering the non-quantized region,and eventually arriving at zero.We suggest a practical experimental setup for our model that can be implemented using electrical circuits.
基金Project supported by the National Natural Science Foundation of China(52374330,52325406)。
文摘The addition of Ce significantly enhances cleanliness of steel and modifies precipitation phases.However,there are differences in the effects of different alloy systems,especially its role in M54 steel is insufficiently understood.This study investigates the evolution of inclusions and precipitation phases in M54 steel ingots with varying Ce additions.Results indicate that the addition of Ce reduces the content of impurity elements(O and S)and transforms Mg and Al inclusions into Ce inclusions,which is due to the stronger affinity between Ce and impurity elements such as O and S.Ce inclusions serve as nucleation sites for dendrites,reducing secondary dendrite arm spacing.In addition,these inclusions and Cecontaining precipitated phase also act as nucleation sites for carbide precipitates,effectively refining their distribution by reducing growth spaces and increasing nucleation density.Notably,as Ce content increases from 0 to 0.01 wt%,the precipitation phase content decreases significantly but rises slightly with further increases in Ce content due to the formation of additional Ce-containing precipitates.By quantitatively comparing the dendrite arm spacing,cleanliness,content and size of precipitated phase,it is determined that the optimum addition amount of Ce for M54 steel is about 0.01 wt%.
基金financially supported by the National Science and Technology Major Project of China(No.J2019-Ⅳ-0011-0125)ND Basic Research Funds of China(No.G2022WD)Shaanxi Province Innovation Capability Support Program(No.2023-CX-TD-47).
文摘Based on α→α2+γ phase transition and crystallographic orientation relationship,as well as the the-ory of grain-preferred growth under high magnetic fields,this study proposes a novel method to adjust the alignment ofα2/γlamellae for TiAl alloys through two-step treatment.The first step involved the pretreatment at 1350℃(αsingle-phase region),followed by high magnetic field heat treatment at the same temperature.Results show that the fraction of α2/γ lamellar orientation with an angle<30°re-specting the magnetic field direction increases significantly to 72.74%for pretreated Ti-42.91Al-0.69Fe alloy after holding for 30 min at 1350℃ with the 10 T magnetic field,compared with the reference sample.The preferred distribution of α2/γ lamellae is attributed to the magnetic driving force generated atαgrain boundaries,which predominantly dominates the preferential growth behavior ofαgrains by influencing the grain boundary migration during the short isothermal time under the 10 T magnetic field.After holding for 5 h at 1350℃,the average grain size of Ti-42.91Al-0.69Fe alloy increases,and the grain boundaries become flatter.Consequently,the curvature driving force generated at theαgrain boundaries is mostly lower than the magnetic driving force.The direction of grain boundary migration is thus pri-marily determined by the direction of magnetic driving forces during the holding time at 1350℃ under the 10 T magnetic field.Specifically,the grain boundaries ofαgrain move towards adjacentαgrains and are swallowed up to grow as the<0001>orientation ofαgrains is normal to the magnetic field direction.Due to the unique habitus plane ofγandαphases,the α2/γ lamellar orientation is approximately par-allel to the magnetic field direction in the subsequent cooling progress.These results indicate that high magnetic field heat treatment atαsingle-phase region can adjust the alignment of α2/γ lamellae.
基金supported by the National Natural Science Foundation of China(Nos.22174067,22204078,22374077,and 22474059)the Natural Science Foundation of Jiangsu Province of China(No.BK20220370)+2 种基金Jiangsu Provincial Department of Education(No.22KJB150009)Jiangsu Association for Science and Technology(No.TJ-2023-076)the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘For chromatographic separation,the reasonable modulation of stationary phases is the key factor to achieve high separation performance.We proposed that developing MOF stationary phases through precisely modulating the thermodynamic interactions between MOFs and analytes is conducive to improving the separation resolution.MIL-125,MIL-125-NH_(2),MIL-143-BTB,and MIL-143-TATB were developed as stationary phases with the careful modulation of organic ligands.MIL-125-NH_(2)and MIL-143-TATB coated columns exhibited much better separation performance than their counterparts,MIL-125 and MIL-143-BTB,respectively.The investigation of the separation mechanism indicated that thermodynamic interaction,rather than kinetic diffusion,was responsible for the separation improvement.MIL-125-NH_(2)and MIL-143-TATB provided stronger and distinguishable interactions with targets than corresponding MIL-125 and MIL-143-BTB,respectively,resulting in enhanced separation performance.This work demonstrates a guide to improving the separation performance of MOF stationary phases by increasing the thermodynamic interactions between MOFs and analytes.
基金supported by National Natural Science Foundation of China(Nos.52325406 and 52374330)Fundamental Research Funds for the Central Universities(No.N2225046).
文摘A mathematical model coupling flow,solidification,strain-stress,and interface failure was developed.Following identification of crack source type through thermal tensile experiment and validation by strain-stress comparison,the model was used to investigate slab cracking tendency near precipitated phases,considering various locations,sizes and shapes of them.The results show that the jet from submerged entry nozzle creates a“double roll”flow pattern during continuous casting,resulting in more uniform temperature distributions at slab corner and wide surface center compared with narrow surface center.Consequently,precipitated phases,particularly those located on the narrow surface,readily induce stress concentration and thus increase cracking tendency.A smaller precipitated phase size can reduce the stress concentration zone,while a more spherical shape can distribute surrounding stress along its surface and lower the internal stress within it,thereby decreasing the risk of slab cracking during continuous casting.The optimal precipitated phase exhibits a spherical or ellipsoidal shape with a major axis of less than 5µm,minimizing its potential to initiate cracks.
