In this study,multilayer lamination welding was employed to prepare graphene/copper(Gr/Cu)composite billets from graphene-coated copper foils,followed by multi-pass cold drawing to produce Φ1 mm Gr/Cu composite wires...In this study,multilayer lamination welding was employed to prepare graphene/copper(Gr/Cu)composite billets from graphene-coated copper foils,followed by multi-pass cold drawing to produce Φ1 mm Gr/Cu composite wires.Microstructure and property analyses in both the cold-drawn and annealed states show that the incorporation of graphene significantly improves the ductility and electrical conductivity of the copper wire.After annealing at 350℃ for 30 minutes,the composite wire demonstrates a tensile strength of 270 MPa and an electrical conductivity of 102.74%IACS,both superior to those of pure copper wire under identical conditions.At 150℃,the electrical conductivity of the annealed composite wire reaches 72.60%IACS,notably higher than the 68.19%IACS of pure copper.The results suggest that graphene is uniformly distributed within the composite wire,with minimal impact on conductivity,while effectively refining the copper grain structure to enhance ductility.Moreover,graphene suppresses copper lattice vibrations at elevated temperatures,reducing the rate of conductivity degradation.展开更多
1.Introduction The strength of metallic materials can be ameliorated by introducing boundaries,precipitates,or defects as obstacles to dislocation movement[1].However,high strength is generally obtained at the sacrifi...1.Introduction The strength of metallic materials can be ameliorated by introducing boundaries,precipitates,or defects as obstacles to dislocation movement[1].However,high strength is generally obtained at the sacrifice of plastic deformation capability[2].Lately,many strategies have been proposed to improve the comprehensive properties of materials,among which manipulating stacking fault energy(SFE)is effective[3–5].展开更多
The adsorption of phosphate was conducted by the complex of chitosan/polyacrylamide/ferric(CS/PAM/Fe(Ⅲ))prepared.The SEM images and XPS spectra confirmed the successful adsorption of phosphate.The adsorption process ...The adsorption of phosphate was conducted by the complex of chitosan/polyacrylamide/ferric(CS/PAM/Fe(Ⅲ))prepared.The SEM images and XPS spectra confirmed the successful adsorption of phosphate.The adsorption process was studied by varying the influencing aspects like pH,co-existing ions,contact time,and initial phosphate concentration.The experimental results indicate that the adsorptive capacity decreases with the increase of pH.However,it is commendable that there is still a adsorption capacity of more than 5 mg/g when the pH is 8-11.The adsorption kinetics can be accurately described by the pseudo-second-order model and is controlled by both chemisorption and surface diffusion.The adsorption process is a single layer adsorption.This paper proposed that the adsorption mechanism of CS/PAM/Fe(Ⅲ)complex is the joint action of electrostatic attraction and ligand exchange.展开更多
Purpose: The purpose of the current study is to investigate the within-pitcher differences in time series angular velocities of the pelvis, trunk, shoulder, and elbow for high and low velocity fastballs in college bas...Purpose: The purpose of the current study is to investigate the within-pitcher differences in time series angular velocities of the pelvis, trunk, shoulder, and elbow for high and low velocity fastballs in college baseball pitchers.Methods: In-game data were retrospectively analyzed from 82 NCAA Division 1 pitchers([1.89 ± 0.06] m, [92.8± 9.5] kg). Kinematic data were collected using an in-game markerless motion capture system. Time series data of pelvis, trunk, shoulder, and elbow angular velocities for each pitcher’s fastest and slowest fastball were extracted for the pitch cycle(foot contact to ball release) and used for analysis. Within-subject time series comparisons were conducted using statistical parametric mapping(SPM) paired samples t-tests(α = 0.012 5).Results: Each of the tested segments were significantly faster in the fastest fastball trial compared to the slowest fastball trial. The duration of significance in reference to the pitch cycle, test statistic, and p-value, for each segment are as follows: Pelvis: 0%–4%, t = 3.54, p = 0.012;Trunk: 30%–67%, t = 5.62, p < 0.001;Shoulder External Rotation: 3%–50%, t =-6.03, p < 0.001;Shoulder Internal Rotation: 96%–100%, t = 4.11, p = 0.008;Elbow: 75%–86%, t = 4.13, p < 0.001.Discussion: Within-subjects differences exist in time series angular velocities when comparing the fastest and slowest fastball. These time series differences provide additional information to distinguish fastball velocity beyond what discrete metrics can provide. Pitchers should look to rotate each segment faster, and optimize the sequencing of these movements, to increase pitch velocity.展开更多
Cu-6%Fe（mass fraction） microcomposites containing（0-0.30）% rare earth elements were prepared by cold drawing and intermediate heat treatments.Microstructure was observed, and mechanical properties and electrical c...Cu-6%Fe（mass fraction） microcomposites containing（0-0.30）% rare earth elements were prepared by cold drawing and intermediate heat treatments.Microstructure was observed, and mechanical properties and electrical conductivity were measured for alloys at various drawing strain levels.Adding rare earth elements could reduce the size of primary Fe and Cu dendrites of Cu-6%Fe.Ultimate tensile strength increased but electrical conductivity decreased with the increase of drawing strain.Rare earth additions in Cu-6%Fe slightly increased the strength at low strain and effectively improved the conductivity at high strain.Both strain hardening rate and conductivity loss of Cu-6%Fe containing rare earths were reduced at lower strain than Cu-6%Fe.展开更多
A pilot wire drawing machine as well as wire end-pointing roller was developed. Using these machines, a wire drawing test for four different coating materials and two different lubricants was performed as the reductio...A pilot wire drawing machine as well as wire end-pointing roller was developed. Using these machines, a wire drawing test for four different coating materials and two different lubricants was performed as the reduction ratio increased from 10% to 30%. Materials used for a substrate in this study are plain carbon steel （AIS11045） and ultra low carbon bainite steel. To compute the friction coefficient between the coating layer of wire and the surface of die lbr a specific lubricant, a series of finite element analyses were carried out. SEM observations were also conducted to investigate the surface defects of wire deformed. Results show that the behavior of drawing force varies with the lubricant-type at the initial stage of drawing. The powder-typed lubricant with a large particle causes the retardation of lull lubrication on the entire contact surface and the local delamination of coating layer on the wire surface. As the flow stress of a substrate increases, the delamination becomes severe.展开更多
Cu-Ag filamentary microcomposites with different Ag contents were prepared by cold drawing and intermediate heat treatments. The microstructure characterization and filamentary distribution were observed for two-phase...Cu-Ag filamentary microcomposites with different Ag contents were prepared by cold drawing and intermediate heat treatments. The microstructure characterization and filamentary distribution were observed for two-phase alloys under different conditions. The effect of heavy drawing strain on the microstructure evolution of Cu-Ag alloys was investigated. The results show that the microstructure components consist of Cu dendrites, eutectic colonies and secondary Ag precipitates in the alloys containing 6%-24% （mass fraction） Ag. With the increase in Ag content, the eutectic colonies in the microstructure increase and gradually change into a continuous net-like distribution. The Cu dendrites, eutectic colonies and secondary Ag precipitates are elongated in an axial direction and developed into the composite filamentary structure during cold drawing deformation. The eutectic colonies tend to evolve into filamentary bundles. The filamentary diameters decrease with the increase in drawing strain degree for the two-phase alloys, in particular for the alloys with low Ag content. The reduction in filamentary diameters becomes slow once the drawing strain has exceeded a certain level.展开更多
Bacteria-associated infection and poor osseointegration are two main reasons for orthopedic implant failure.Ti-Cu alloy exhibited excellent antibacterial property,but still presented unsatisfied osteogenic activities....Bacteria-associated infection and poor osseointegration are two main reasons for orthopedic implant failure.Ti-Cu alloy exhibited excellent antibacterial property,but still presented unsatisfied osteogenic activities.Therefore,Ti-Cu alloy was surface modified by an alkali-heat treatment in this paper to improve the osteogenic ability without reduction in antibacterial ability.A TiO_(2)/CuO/Cu_(2)O composite coating with nanostructure was deposited on Ti-Cu alloy.The coating showed increased roughness and great hydrophilicity.Antibacterial tests indicated that the modified Ti-Cu alloy exhibited stronger antibacterial ability against Staphylococcus aureus(S.aureus)than Ti-Cu alloy.Meanwhile,cell experiments demonstrated that the composite coating promoted initial adhesion and spreading of MC3T3-E1 cells,enhanced alkaline phosphatase(ALP)activities as well as extracellular matrix(ECM)mineralization,and significantly upregulated osteogenesis-related gene expressions.It was suggested that the nano-structured TiO_(2)/CuO/Cu_(2)O coating on Ti-Cu alloy might provide a potential strategy for orthopedic implant failure.展开更多
An FE model was developed to study thermal behavior during the rod and wire hot continuous rolling process. The FE code MSC. Marc was used in the simulation using implicit static arithmetic. The whole rolling process ...An FE model was developed to study thermal behavior during the rod and wire hot continuous rolling process. The FE code MSC. Marc was used in the simulation using implicit static arithmetic. The whole rolling process of 30 passes was separated and simulated with several continuous 3D elastic-plastic FE models. A rigid pushing body and a data transfer technique were introduced into this model. The on-line experiments were conducted on 304 stainless steel and GCr15 steel hot continuous rolling process to prove the results of simulation by implicit static FEM. The results show that the temperature results of finite element simulations are in good agreement with experiments, which indicate that the FE model developed in this study is effective and efficient.展开更多
Central region coarse grains and centerline segregation are common defects in aluminum ingots fabricated by direct chill(DC)casting.A double cooling field was introduced into the DC casting process to reduce these def...Central region coarse grains and centerline segregation are common defects in aluminum ingots fabricated by direct chill(DC)casting.A double cooling field was introduced into the DC casting process to reduce these defects,whereby the external cooling was supplied by the mold and water jets,and intercooling was achieved by inserting a rod of the same alloy into the molten pool along the central axis of the ingot.Rather than forming a good metallurgical interface during solid-liquid compound casting,in the present work,the purpose of inserting the rod is to enforce internal cooling and consequently decrease the sump depth.Moreover,the insertion provides more nucleation sites with the unmoltenα-Al particles.The structure and the macrosegregation of 2024 Al alloy ingots prepared by DC casting with and without the inserts were investigated.Results show that when the inserting position is 50 mm above the upper edge of the graphite ring,significant grain refinement in the central region of the ingot and a reduced centerline segregation are achieved.展开更多
To move the performance of lithium-ion batteries into the next stage,the modification of the structure of cells is the only choice except for the development of materials exhibiting higher performance.In this review p...To move the performance of lithium-ion batteries into the next stage,the modification of the structure of cells is the only choice except for the development of materials exhibiting higher performance.In this review paper,the employment of through-holing structures of anodes and cathodes prepared with a picosecond pulsed laser has been proposed.The laser system and the structure for improving the battery performance were introduced.The performance of laminated cells constructed with through-holed anodes and cathodes was reviewed from the viewpoints of the improvement of high-rate performance and energy density,removal of unbalanced capacities on both sides of the current collector,even greater high-rate performance by hybridizing cathode materials and removal of irreversible capacity.In conclusion,the points that should be examined and the problem for the through-holed structure to be in practical use are summarized.展开更多
This paper presents an energy-efficient control strategy for electric vehicles(EVs)driven by in-wheel-motors(IWMs)based on discrete adaptive sliding mode control(DASMC).The nonlinear vehicle model,tire model and IWM m...This paper presents an energy-efficient control strategy for electric vehicles(EVs)driven by in-wheel-motors(IWMs)based on discrete adaptive sliding mode control(DASMC).The nonlinear vehicle model,tire model and IWM model are established at first to represent the operation mechanism of the whole system.Based on the modeling,two virtual control variables are used to represent the longitudinal and yaw control efforts to coordinate the vehicle motion control.Then DASMC method is applied to calculate the required total driving torque and yaw moment,which can improve the tracking performance as well as the system robustness.According to the vehicle nonlinear model,the additional yaw moment can be expressed as a function of longitudinal and lateral tire forces.For further control scheme development,a tire force estimator using an unscented Kalman filter is designed to estimate real-time tire forces.On these bases,energy efficient torque allocation method is developed to distribute the total driving torque and differential torque to each IWM,considering the motor energy consumption,the tire slip energy consumption,and the brake energy~?recovery.Simulation results of the proposed control strategy using the co-platform of Matlab/Simulink and CarSim way.展开更多
This article aims to explore the age hardening responses of both as-extruded and as-aged Mg-2.5 Sn-1.5 Ca-x Al alloys(x=2.0,4.0 and 9.0 wt%,termed TXA322,TXA324 and TXA329,respectively)through microstructural and mech...This article aims to explore the age hardening responses of both as-extruded and as-aged Mg-2.5 Sn-1.5 Ca-x Al alloys(x=2.0,4.0 and 9.0 wt%,termed TXA322,TXA324 and TXA329,respectively)through microstructural and mechanical characterization.Results indicate that grain size of as-extruded TXA322,TXA324 and TXA329 alloys were^16μm,~10μm and^12μm,respectively.A number of<a>and<c+a>dislocations were observed in all the as-extruded samples.Guinier–Preston(GP)zones were evidently identified in TXA322 alloy,while only a small number of Mg17 Al12 phases existed in both TXA324 and TXA329 alloys.An aging treatment facilitated the precipitation of a high number density of GP zones within the matrix of TXA322 alloy.In contrast,no obvious nano-precipitates were in as-aged TXA324 alloy.Numerous nano-Mg17 Al12 phases were formed through a following aging treatment in TXA329 alloy.In terms of mechanical properties,it is apparent that an increment in ultimate tensile strength of^46 MPa and^40 MPa was yielded in peak-aged TXA322 and TXA329 alloys,while no obvious variations in UTS were present in peak-aged TXA324 alloy,in comparison with the as-extruded counterparts.展开更多
Microstructure inhomogeneity and negative segregation have long been challenges for large-size alloy ingots,directly affecting the downstream processing and final performance of products.Here,we used2024 aluminum allo...Microstructure inhomogeneity and negative segregation have long been challenges for large-size alloy ingots,directly affecting the downstream processing and final performance of products.Here,we used2024 aluminum alloy as a model alloy to propose a technique,named double-cooling field casting,i.e.,one 2024 Al alloy rod(Φ20 mm)at room temperature was introduced into the melt along the central axis of the hot-top with the protection of a thermal-insulation tube during the direct chill(DC)casting process of aΦ300 mm 2024 Al alloy ingot.The results show that the introduction of the same alloy solid insert has a remarkable influence on refining grains in the center region of the ingot,reducing negative centerline segregation and decreasing the depth of the center part of the sump.With the application of the 2024 Al insert,the mean size of equiaxed grains at the center part of the ingot decreased from1204±132μm to 721±69μm.The relative deviation of the Cu and Mg main solutes reduced from-0.062 and-0.054 to-0.03 and-0.024,respectively,and the sump depth decreased from 280 mm to242 mm.Moreover,the shape of the solidification front was changed from‘V’-shaped to‘W’-shaped.The ingot quality was thus improved,mainly arising from the dissolution of the cold 2024 Al insert at a proper position of the hot-top counteracting some latent heat of solidification of the ingot,dissipating the heat of the central part of the hot-top by conducting the 2024 Al insert to the outside,and providing extra-nuclei from the unmoltenα-Al particles of the insert.展开更多
The interface between metal nanoparticles(NPs)and support plays a vital role in catalysis because both electron and atom exchanges occur across the metal-support interface.However,the rational design of interfacial st...The interface between metal nanoparticles(NPs)and support plays a vital role in catalysis because both electron and atom exchanges occur across the metal-support interface.However,the rational design of interfacial structure facilitating the charge transfer between the neighboring parts remains a challenge.Herein,a guided nucleation strategy based on redox reaction between noble metal precursor and supportsurface is introduced to construct epitaxial interfaces between Pt NPs and CeO2 support.The Pt/CeO2 catalyst exhibits near room temperature catalytic activity for CO oxidation that is benefited from the well-defined interface structure facilitating charge transfer from CeO2 support to Pt NPs.Meanwhile,this general approach based on support-surface-induced-nucleation was successfully extended to synthesize Pd and Cu nanocatalysts on CeO2,demonstrating its universal and feasible characteristics.This work is an important step towards developing highly active supported metal catalysts by engineering their interfaces.展开更多
A Cu-10wt%Fe composite was prepared through hot-pressed sintering,and the material was subsequently solution treated.The hot-pressed sintered and solution treated materials were rolled and aged.The precipitation behav...A Cu-10wt%Fe composite was prepared through hot-pressed sintering,and the material was subsequently solution treated.The hot-pressed sintered and solution treated materials were rolled and aged.The precipitation behavior and performance changes were systematically studied by using scanning electron microscopy and transmission electron microscopy.In contrast to the hot-pressed sintered specimen,the solution treatment significantly affects the thermal stability and properties of the Cu-10wt%Fe composite.The Cu-10wt%Fe composite was prepared after solid solution,cold rolling and aging at 773 K for 1 h,and it obtained excellent tensile strength of 494 MPa,uniform elongation of 16.3%,electrical conductivity of 51.1%IACS and softening temperature of 838 K.Mechanisms for the distinct difference in thermal stability and properties between hot-pressed sintered and solution treated specimens were analyzed.These findings provide a theoretical basis for designing high-performance Cu-based in-situ composites by post treatment.展开更多
Nano structured Cu-/Al-laminated composites were processed by accumulative roll-bonding(ARB)technique for four cycles.Microstructural evolutions inside the Cu and Al layers and the interfacial reactions were revealed ...Nano structured Cu-/Al-laminated composites were processed by accumulative roll-bonding(ARB)technique for four cycles.Microstructural evolutions inside the Cu and Al layers and the interfacial reactions were revealed after annealing at different temperatures.Recovery and recrystallization occurred in the Cu and Al layers at low annealing temperatures,and three kinds of intermetallic compounds formed near the interfaces.The mechanical properties of these composites after annealing were investigated by tensile tests,and the variation of strength-ductility synergy was comprehensively discussed by considering the roles of constituent and the intermetallic compounds.展开更多
Antibacterial Ti-5Cu alloy is a promising substitute material for Ti-made cardiovascular implants,so its surface engineering is crucial to expediting clinical implementation.Given the antibacterial and cardiovas-cular...Antibacterial Ti-5Cu alloy is a promising substitute material for Ti-made cardiovascular implants,so its surface engineering is crucial to expediting clinical implementation.Given the antibacterial and cardiovas-cular biological benefits of Cu^(2+)and titanium-nitride-oxide(TiN x O y)coatings,a Cu_(2)O/CuO-TiN x O y coating with upregulated Cu^(2+)release was successfully deposited on Ti-5Cu alloy for the first time using oxygen and nitrogen plasma-based surface modification.The superhydrophilic and nanostructured Cu_(2)O/CuO-TiN x O y coating had a dense structure and was well bonded to the substrate,resulting in enhanced cor-rosion resistance,while CuO/Cu_(2)O in the coating released Cu^(2+)faster than Ti_(2)Cu phase in the matrix.More gratifying,the coating demonstrated perfect antibacterial properties(R>99.9%against S.aureus),owing primarily to direct contact sterilization of Cu_(2)O/CuO.The most encouraging phenomenon was that the coating dramatically accelerated HUVEC adhesion(1.4 times),proliferation(RGR:106%-116%),and particularly migration(RMR:158%-247%)compared with the control Ti.The coating extract also signifi-cantly stimulated in vitro angiogenesis capacity.The rapid endothelialization for Cu_(2)O/CuO-TiN x O y coating was attributed to the surface nanostructure and Cu^(2+)/NO_(2)−release,which upregulated the angiogenesis-related gene expression of HIF-1α,VEGF,and eNOS to increase VEGF secretion and NO production.All of the findings indicated that the Cu_(2)O/CuO-TiN x O y coating could enhance the corrosion resistance,an-tibacterial properties,and endothelialization potential of Ti-Cu alloy,displaying great clinical potential in cardiovascular applications.展开更多
Ti-Cu alloys have strong antibacterial proper-ties,high strength and excellent corrosion resistance,which might be used in orthopedic and dental implants.In this paper,the tribocorrosion behaviors of Ti-Cu alloy with ...Ti-Cu alloys have strong antibacterial proper-ties,high strength and excellent corrosion resistance,which might be used in orthopedic and dental implants.In this paper,the tribocorrosion behaviors of Ti-Cu alloy with different Cu contents were investigated in four simulated biological environments compared with cp-Ti.The results showed that Ti-Cu sintered alloy exhibited higher corro-sion resistance,lower coefficient friction and wear loss than cp-Ti in all tested solutions due to the formation of fine and homogeneously distributed Ti_(2)Cu phase,espe-cially in solution with lower F ion and pH.High Cu content and extrusion process improved the corrosion resistance and the wear resistance because of high Ti_(2)Cu phase fraction and fine grain size.However,aggressive solution,such as the solution with lower F ion and pH,accelerated wear in comparison with other solutions for cp-Ti and Ti-Cu sintered alloys.Scanning electron microscope(SEM)surface morphology demonstrated that the wear mecha-nism of cp-Ti during tribocorrosion process was mainly abrasive wear and adhesive wear while that of Ti-Cu alloy was abrasive wear.In summary,Ti-Cu sintered alloys showed much better tribocorrosion property than cp-Ti,which shows great potential application in condition for wear and corrosion resistance.展开更多
The so-called bimodal microstructure of Ti-6 Al-4 V alloy,composed of primaryαgrains(α_(p))and transformed β areas(β_(trans)),can be regarded as a"dual-phase"structure to some extent,the mechanical prope...The so-called bimodal microstructure of Ti-6 Al-4 V alloy,composed of primaryαgrains(α_(p))and transformed β areas(β_(trans)),can be regarded as a"dual-phase"structure to some extent,the mechanical properties of which are closely related to the sizes,volume fractions,distributions as well as nanohardness of the two constituents.In this study,the volume fractions of primaryαgrains(vol.%(α_(p)))were systematically modified in three series of bimodal microstructures with fixed primaryαgrain sizes(0.8μm,2.4μm and 5.0μm),by changing the intercritical annealing temperature(T_(int)).By evaluating the tensile properties at room temperature,it was found that with increasing T_(int)(decreasing vol.%(α_(p))),the yield strength of bimodal microstructures monotonically increased,while the uniform elongation firstly increased with T_(int)until 910°C and then drastically decreased afterwards,thereby dividing the T_(int)into two regions,namely region I(830-910°C)and region II(910-970℃).The detailed deformation behaviors within the two regions were studied and compared,from the perspectives of strain distribution analysis,slip system analysis as well as dislocation analysis.For bimodal microstructures in region I,due to the much lower nano-hardness ofβ_(trans)thanα_(p),there was a clear strain partitioning between the two constituents as well as a strain gradient from theα_(p)/β_(trans)interface to the grain interior ofα_(p).This activated a large number of geometrically necessary dislocations(GNDs)near the interface,mostly with components,which contributed greatly to the extraordinary work-hardening abilities of bimodal microstructures in region I.With increasing T_(int),theα_(p)/β_(trans)interface length density gradually increased and so was the density of GNDs with components,which explained the continuous increase of uniform elongation with T_(int)in this region.For bimodal microstructures in region II,where the nano-hardness ofβ_(trans)andα_(p)were comparable,neither a clear strain-partitioning tendency nor a strain gradient across theα_(p)/β_(trans)interface was observed.Consequently,only statistically stored dislocations(SSDs)with component were activated insideα_(p).The absence of dislocations together with a decreased volume fraction ofα_(p)resulted into a dramatic loss of uniform elongation for bimodal microstructures in region II.展开更多
基金Funded by Hunan Provincial Natural Science Foundation(No.2023JJ40074)Hunan Provincial Education Department Excellent Youth Project(No.21B0757)Hunan Provincial Engineering Technology Center(No.2022TP2036)。
文摘In this study,multilayer lamination welding was employed to prepare graphene/copper(Gr/Cu)composite billets from graphene-coated copper foils,followed by multi-pass cold drawing to produce Φ1 mm Gr/Cu composite wires.Microstructure and property analyses in both the cold-drawn and annealed states show that the incorporation of graphene significantly improves the ductility and electrical conductivity of the copper wire.After annealing at 350℃ for 30 minutes,the composite wire demonstrates a tensile strength of 270 MPa and an electrical conductivity of 102.74%IACS,both superior to those of pure copper wire under identical conditions.At 150℃,the electrical conductivity of the annealed composite wire reaches 72.60%IACS,notably higher than the 68.19%IACS of pure copper.The results suggest that graphene is uniformly distributed within the composite wire,with minimal impact on conductivity,while effectively refining the copper grain structure to enhance ductility.Moreover,graphene suppresses copper lattice vibrations at elevated temperatures,reducing the rate of conductivity degradation.
基金financially supported by the National Natural Science Foundation of China(NSFC)under grant No.52371100.
文摘1.Introduction The strength of metallic materials can be ameliorated by introducing boundaries,precipitates,or defects as obstacles to dislocation movement[1].However,high strength is generally obtained at the sacrifice of plastic deformation capability[2].Lately,many strategies have been proposed to improve the comprehensive properties of materials,among which manipulating stacking fault energy(SFE)is effective[3–5].
基金Funded by the Provincial Natural Science Foundation for Universities of AnhuiChina(No.KJ2021A0624)+1 种基金the Director's Fund of Anhui Province Advanced Building Materials International Research Center(No.JZCL2207ZR)the Anhui Jianzhu University Talent Introduction and Doctoral Start-up Fund(No.2023QDZ23)。
文摘The adsorption of phosphate was conducted by the complex of chitosan/polyacrylamide/ferric(CS/PAM/Fe(Ⅲ))prepared.The SEM images and XPS spectra confirmed the successful adsorption of phosphate.The adsorption process was studied by varying the influencing aspects like pH,co-existing ions,contact time,and initial phosphate concentration.The experimental results indicate that the adsorptive capacity decreases with the increase of pH.However,it is commendable that there is still a adsorption capacity of more than 5 mg/g when the pH is 8-11.The adsorption kinetics can be accurately described by the pseudo-second-order model and is controlled by both chemisorption and surface diffusion.The adsorption process is a single layer adsorption.This paper proposed that the adsorption mechanism of CS/PAM/Fe(Ⅲ)complex is the joint action of electrostatic attraction and ligand exchange.
文摘Purpose: The purpose of the current study is to investigate the within-pitcher differences in time series angular velocities of the pelvis, trunk, shoulder, and elbow for high and low velocity fastballs in college baseball pitchers.Methods: In-game data were retrospectively analyzed from 82 NCAA Division 1 pitchers([1.89 ± 0.06] m, [92.8± 9.5] kg). Kinematic data were collected using an in-game markerless motion capture system. Time series data of pelvis, trunk, shoulder, and elbow angular velocities for each pitcher’s fastest and slowest fastball were extracted for the pitch cycle(foot contact to ball release) and used for analysis. Within-subject time series comparisons were conducted using statistical parametric mapping(SPM) paired samples t-tests(α = 0.012 5).Results: Each of the tested segments were significantly faster in the fastest fastball trial compared to the slowest fastball trial. The duration of significance in reference to the pitch cycle, test statistic, and p-value, for each segment are as follows: Pelvis: 0%–4%, t = 3.54, p = 0.012;Trunk: 30%–67%, t = 5.62, p < 0.001;Shoulder External Rotation: 3%–50%, t =-6.03, p < 0.001;Shoulder Internal Rotation: 96%–100%, t = 4.11, p = 0.008;Elbow: 75%–86%, t = 4.13, p < 0.001.Discussion: Within-subjects differences exist in time series angular velocities when comparing the fastest and slowest fastball. These time series differences provide additional information to distinguish fastball velocity beyond what discrete metrics can provide. Pitchers should look to rotate each segment faster, and optimize the sequencing of these movements, to increase pitch velocity.
基金supported by the National Natural Science Foundation of China (50671092)
文摘Cu-6%Fe（mass fraction） microcomposites containing（0-0.30）% rare earth elements were prepared by cold drawing and intermediate heat treatments.Microstructure was observed, and mechanical properties and electrical conductivity were measured for alloys at various drawing strain levels.Adding rare earth elements could reduce the size of primary Fe and Cu dendrites of Cu-6%Fe.Ultimate tensile strength increased but electrical conductivity decreased with the increase of drawing strain.Rare earth additions in Cu-6%Fe slightly increased the strength at low strain and effectively improved the conductivity at high strain.Both strain hardening rate and conductivity loss of Cu-6%Fe containing rare earths were reduced at lower strain than Cu-6%Fe.
基金supported by research funds from Dong-A University, Korea
文摘A pilot wire drawing machine as well as wire end-pointing roller was developed. Using these machines, a wire drawing test for four different coating materials and two different lubricants was performed as the reduction ratio increased from 10% to 30%. Materials used for a substrate in this study are plain carbon steel （AIS11045） and ultra low carbon bainite steel. To compute the friction coefficient between the coating layer of wire and the surface of die lbr a specific lubricant, a series of finite element analyses were carried out. SEM observations were also conducted to investigate the surface defects of wire deformed. Results show that the behavior of drawing force varies with the lubricant-type at the initial stage of drawing. The powder-typed lubricant with a large particle causes the retardation of lull lubrication on the entire contact surface and the local delamination of coating layer on the wire surface. As the flow stress of a substrate increases, the delamination becomes severe.
基金Project (No. 50671092) supported by the National Natural Science Foundation of China
文摘Cu-Ag filamentary microcomposites with different Ag contents were prepared by cold drawing and intermediate heat treatments. The microstructure characterization and filamentary distribution were observed for two-phase alloys under different conditions. The effect of heavy drawing strain on the microstructure evolution of Cu-Ag alloys was investigated. The results show that the microstructure components consist of Cu dendrites, eutectic colonies and secondary Ag precipitates in the alloys containing 6%-24% （mass fraction） Ag. With the increase in Ag content, the eutectic colonies in the microstructure increase and gradually change into a continuous net-like distribution. The Cu dendrites, eutectic colonies and secondary Ag precipitates are elongated in an axial direction and developed into the composite filamentary structure during cold drawing deformation. The eutectic colonies tend to evolve into filamentary bundles. The filamentary diameters decrease with the increase in drawing strain degree for the two-phase alloys, in particular for the alloys with low Ag content. The reduction in filamentary diameters becomes slow once the drawing strain has exceeded a certain level.
基金financial support from the National Natural Science Foundation of China(No.31971253)。
文摘Bacteria-associated infection and poor osseointegration are two main reasons for orthopedic implant failure.Ti-Cu alloy exhibited excellent antibacterial property,but still presented unsatisfied osteogenic activities.Therefore,Ti-Cu alloy was surface modified by an alkali-heat treatment in this paper to improve the osteogenic ability without reduction in antibacterial ability.A TiO_(2)/CuO/Cu_(2)O composite coating with nanostructure was deposited on Ti-Cu alloy.The coating showed increased roughness and great hydrophilicity.Antibacterial tests indicated that the modified Ti-Cu alloy exhibited stronger antibacterial ability against Staphylococcus aureus(S.aureus)than Ti-Cu alloy.Meanwhile,cell experiments demonstrated that the composite coating promoted initial adhesion and spreading of MC3T3-E1 cells,enhanced alkaline phosphatase(ALP)activities as well as extracellular matrix(ECM)mineralization,and significantly upregulated osteogenesis-related gene expressions.It was suggested that the nano-structured TiO_(2)/CuO/Cu_(2)O coating on Ti-Cu alloy might provide a potential strategy for orthopedic implant failure.
基金Item Sponsored by Youth Science Technology Elitist Foundation of Dalian Local Government (2001-122)
文摘An FE model was developed to study thermal behavior during the rod and wire hot continuous rolling process. The FE code MSC. Marc was used in the simulation using implicit static arithmetic. The whole rolling process of 30 passes was separated and simulated with several continuous 3D elastic-plastic FE models. A rigid pushing body and a data transfer technique were introduced into this model. The on-line experiments were conducted on 304 stainless steel and GCr15 steel hot continuous rolling process to prove the results of simulation by implicit static FEM. The results show that the temperature results of finite element simulations are in good agreement with experiments, which indicate that the FE model developed in this study is effective and efficient.
基金financially supported by the Natural Science Foundation of Liaoning Province(Nos.2019-ZD-0002,2019KF-0503)the Fundamental Research Funds for the Central Universities(Nos.N2002025,N2109006)the National Natural Science Foundation of China(No.51674078)。
文摘Central region coarse grains and centerline segregation are common defects in aluminum ingots fabricated by direct chill(DC)casting.A double cooling field was introduced into the DC casting process to reduce these defects,whereby the external cooling was supplied by the mold and water jets,and intercooling was achieved by inserting a rod of the same alloy into the molten pool along the central axis of the ingot.Rather than forming a good metallurgical interface during solid-liquid compound casting,in the present work,the purpose of inserting the rod is to enforce internal cooling and consequently decrease the sump depth.Moreover,the insertion provides more nucleation sites with the unmoltenα-Al particles.The structure and the macrosegregation of 2024 Al alloy ingots prepared by DC casting with and without the inserts were investigated.Results show that when the inserting position is 50 mm above the upper edge of the graphite ring,significant grain refinement in the central region of the ingot and a reduced centerline segregation are achieved.
文摘To move the performance of lithium-ion batteries into the next stage,the modification of the structure of cells is the only choice except for the development of materials exhibiting higher performance.In this review paper,the employment of through-holing structures of anodes and cathodes prepared with a picosecond pulsed laser has been proposed.The laser system and the structure for improving the battery performance were introduced.The performance of laminated cells constructed with through-holed anodes and cathodes was reviewed from the viewpoints of the improvement of high-rate performance and energy density,removal of unbalanced capacities on both sides of the current collector,even greater high-rate performance by hybridizing cathode materials and removal of irreversible capacity.In conclusion,the points that should be examined and the problem for the through-holed structure to be in practical use are summarized.
基金Supported by Jiangsu Provincial Key R&D Plan (Grant No.BE2022053)Youth Fund of Jiangsu Provincial Natural Science Foundation (Grant No.BK20200423)National Natural Science Foundation of China (Grant No.5210120245)。
文摘This paper presents an energy-efficient control strategy for electric vehicles(EVs)driven by in-wheel-motors(IWMs)based on discrete adaptive sliding mode control(DASMC).The nonlinear vehicle model,tire model and IWM model are established at first to represent the operation mechanism of the whole system.Based on the modeling,two virtual control variables are used to represent the longitudinal and yaw control efforts to coordinate the vehicle motion control.Then DASMC method is applied to calculate the required total driving torque and yaw moment,which can improve the tracking performance as well as the system robustness.According to the vehicle nonlinear model,the additional yaw moment can be expressed as a function of longitudinal and lateral tire forces.For further control scheme development,a tire force estimator using an unscented Kalman filter is designed to estimate real-time tire forces.On these bases,energy efficient torque allocation method is developed to distribute the total driving torque and differential torque to each IWM,considering the motor energy consumption,the tire slip energy consumption,and the brake energy~?recovery.Simulation results of the proposed control strategy using the co-platform of Matlab/Simulink and CarSim way.
基金supported financially by the National Key Research and Development Program of China(Nos.2016YFB0301105 and 2016YFB0701200)the National Natural Science Foundation of China(Nos.51701211,51971053 and U1610253)+1 种基金the Fundamental Research Funds for the Central Universities(No.N170204011)the Fund of the state Key Laboratory of Solidification Processing in NPU(No.SKLSP201920).
文摘This article aims to explore the age hardening responses of both as-extruded and as-aged Mg-2.5 Sn-1.5 Ca-x Al alloys(x=2.0,4.0 and 9.0 wt%,termed TXA322,TXA324 and TXA329,respectively)through microstructural and mechanical characterization.Results indicate that grain size of as-extruded TXA322,TXA324 and TXA329 alloys were^16μm,~10μm and^12μm,respectively.A number of<a>and<c+a>dislocations were observed in all the as-extruded samples.Guinier–Preston(GP)zones were evidently identified in TXA322 alloy,while only a small number of Mg17 Al12 phases existed in both TXA324 and TXA329 alloys.An aging treatment facilitated the precipitation of a high number density of GP zones within the matrix of TXA322 alloy.In contrast,no obvious nano-precipitates were in as-aged TXA324 alloy.Numerous nano-Mg17 Al12 phases were formed through a following aging treatment in TXA329 alloy.In terms of mechanical properties,it is apparent that an increment in ultimate tensile strength of^46 MPa and^40 MPa was yielded in peak-aged TXA322 and TXA329 alloys,while no obvious variations in UTS were present in peak-aged TXA324 alloy,in comparison with the as-extruded counterparts.
基金financially supported by the Fundamental Research Funds for the Central Universities(Nos.N2002025,N2109006 and N2109007)the Project of Promoting Talents in Liaoning Province(No.XLYC1808038)。
文摘Microstructure inhomogeneity and negative segregation have long been challenges for large-size alloy ingots,directly affecting the downstream processing and final performance of products.Here,we used2024 aluminum alloy as a model alloy to propose a technique,named double-cooling field casting,i.e.,one 2024 Al alloy rod(Φ20 mm)at room temperature was introduced into the melt along the central axis of the hot-top with the protection of a thermal-insulation tube during the direct chill(DC)casting process of aΦ300 mm 2024 Al alloy ingot.The results show that the introduction of the same alloy solid insert has a remarkable influence on refining grains in the center region of the ingot,reducing negative centerline segregation and decreasing the depth of the center part of the sump.With the application of the 2024 Al insert,the mean size of equiaxed grains at the center part of the ingot decreased from1204±132μm to 721±69μm.The relative deviation of the Cu and Mg main solutes reduced from-0.062 and-0.054 to-0.03 and-0.024,respectively,and the sump depth decreased from 280 mm to242 mm.Moreover,the shape of the solidification front was changed from‘V’-shaped to‘W’-shaped.The ingot quality was thus improved,mainly arising from the dissolution of the cold 2024 Al insert at a proper position of the hot-top counteracting some latent heat of solidification of the ingot,dissipating the heat of the central part of the hot-top by conducting the 2024 Al insert to the outside,and providing extra-nuclei from the unmoltenα-Al particles of the insert.
基金supported by the National Natural Science Foundation of China(Nos.51771047,51525101,U1602275,51601119)the Fundamental Research Funds for the Central Universities(N180204014)+1 种基金the Key Lab for ATM of Northeastern University(China)the Natural Science Foundation of Shenzhen University(No.2019006).
文摘The interface between metal nanoparticles(NPs)and support plays a vital role in catalysis because both electron and atom exchanges occur across the metal-support interface.However,the rational design of interfacial structure facilitating the charge transfer between the neighboring parts remains a challenge.Herein,a guided nucleation strategy based on redox reaction between noble metal precursor and supportsurface is introduced to construct epitaxial interfaces between Pt NPs and CeO2 support.The Pt/CeO2 catalyst exhibits near room temperature catalytic activity for CO oxidation that is benefited from the well-defined interface structure facilitating charge transfer from CeO2 support to Pt NPs.Meanwhile,this general approach based on support-surface-induced-nucleation was successfully extended to synthesize Pd and Cu nanocatalysts on CeO2,demonstrating its universal and feasible characteristics.This work is an important step towards developing highly active supported metal catalysts by engineering their interfaces.
基金This work was supported by the National Natural Science Foundation of China(Grant No.52101181).
文摘A Cu-10wt%Fe composite was prepared through hot-pressed sintering,and the material was subsequently solution treated.The hot-pressed sintered and solution treated materials were rolled and aged.The precipitation behavior and performance changes were systematically studied by using scanning electron microscopy and transmission electron microscopy.In contrast to the hot-pressed sintered specimen,the solution treatment significantly affects the thermal stability and properties of the Cu-10wt%Fe composite.The Cu-10wt%Fe composite was prepared after solid solution,cold rolling and aging at 773 K for 1 h,and it obtained excellent tensile strength of 494 MPa,uniform elongation of 16.3%,electrical conductivity of 51.1%IACS and softening temperature of 838 K.Mechanisms for the distinct difference in thermal stability and properties between hot-pressed sintered and solution treated specimens were analyzed.These findings provide a theoretical basis for designing high-performance Cu-based in-situ composites by post treatment.
基金financially supported by the Fundamental Research Funds for the Central Universities under grant No.N180204015the National Natural Science Foundation of China(NSFC)under Grant No.51331007。
文摘Nano structured Cu-/Al-laminated composites were processed by accumulative roll-bonding(ARB)technique for four cycles.Microstructural evolutions inside the Cu and Al layers and the interfacial reactions were revealed after annealing at different temperatures.Recovery and recrystallization occurred in the Cu and Al layers at low annealing temperatures,and three kinds of intermetallic compounds formed near the interfaces.The mechanical properties of these composites after annealing were investigated by tensile tests,and the variation of strength-ductility synergy was comprehensively discussed by considering the roles of constituent and the intermetallic compounds.
基金supported by the National Key R&D Program of China(No.2022YFB3804400)and(No.2022YFE0122800)Research Program(No.62602010113)+1 种基金Na-tional Natural Science Foundation of China(No.31971253/C1002)Beijing Municipal Health Commission(Nos.BMHC-2021-6,BMHC-2019-9,PXM 2020_026275_000002).
文摘Antibacterial Ti-5Cu alloy is a promising substitute material for Ti-made cardiovascular implants,so its surface engineering is crucial to expediting clinical implementation.Given the antibacterial and cardiovas-cular biological benefits of Cu^(2+)and titanium-nitride-oxide(TiN x O y)coatings,a Cu_(2)O/CuO-TiN x O y coating with upregulated Cu^(2+)release was successfully deposited on Ti-5Cu alloy for the first time using oxygen and nitrogen plasma-based surface modification.The superhydrophilic and nanostructured Cu_(2)O/CuO-TiN x O y coating had a dense structure and was well bonded to the substrate,resulting in enhanced cor-rosion resistance,while CuO/Cu_(2)O in the coating released Cu^(2+)faster than Ti_(2)Cu phase in the matrix.More gratifying,the coating demonstrated perfect antibacterial properties(R>99.9%against S.aureus),owing primarily to direct contact sterilization of Cu_(2)O/CuO.The most encouraging phenomenon was that the coating dramatically accelerated HUVEC adhesion(1.4 times),proliferation(RGR:106%-116%),and particularly migration(RMR:158%-247%)compared with the control Ti.The coating extract also signifi-cantly stimulated in vitro angiogenesis capacity.The rapid endothelialization for Cu_(2)O/CuO-TiN x O y coating was attributed to the surface nanostructure and Cu^(2+)/NO_(2)−release,which upregulated the angiogenesis-related gene expression of HIF-1α,VEGF,and eNOS to increase VEGF secretion and NO production.All of the findings indicated that the Cu_(2)O/CuO-TiN x O y coating could enhance the corrosion resistance,an-tibacterial properties,and endothelialization potential of Ti-Cu alloy,displaying great clinical potential in cardiovascular applications.
基金financially supported by the National Natural Science Foundation (No.31971253)Heilongjiang Provincial Basic Scientific Research Business Fund for Universities (No.2018-KYYWF-0931)
文摘Ti-Cu alloys have strong antibacterial proper-ties,high strength and excellent corrosion resistance,which might be used in orthopedic and dental implants.In this paper,the tribocorrosion behaviors of Ti-Cu alloy with different Cu contents were investigated in four simulated biological environments compared with cp-Ti.The results showed that Ti-Cu sintered alloy exhibited higher corro-sion resistance,lower coefficient friction and wear loss than cp-Ti in all tested solutions due to the formation of fine and homogeneously distributed Ti_(2)Cu phase,espe-cially in solution with lower F ion and pH.High Cu content and extrusion process improved the corrosion resistance and the wear resistance because of high Ti_(2)Cu phase fraction and fine grain size.However,aggressive solution,such as the solution with lower F ion and pH,accelerated wear in comparison with other solutions for cp-Ti and Ti-Cu sintered alloys.Scanning electron microscope(SEM)surface morphology demonstrated that the wear mecha-nism of cp-Ti during tribocorrosion process was mainly abrasive wear and adhesive wear while that of Ti-Cu alloy was abrasive wear.In summary,Ti-Cu sintered alloys showed much better tribocorrosion property than cp-Ti,which shows great potential application in condition for wear and corrosion resistance.
基金financial support from Cross-ministerial Strategic Innovation Promotion Program(SIP)supported by the Cabinet Office of Japanese government and the Elements Strategy Initiative for Structural Materials(ESISM)in Kyoto University supported by the Ministry of Education,Culture,Sports,Science and Technology(MEXT),Japansupport by the Fundamental Research Funds for the Central Universities under grant No.N180204015。
文摘The so-called bimodal microstructure of Ti-6 Al-4 V alloy,composed of primaryαgrains(α_(p))and transformed β areas(β_(trans)),can be regarded as a"dual-phase"structure to some extent,the mechanical properties of which are closely related to the sizes,volume fractions,distributions as well as nanohardness of the two constituents.In this study,the volume fractions of primaryαgrains(vol.%(α_(p)))were systematically modified in three series of bimodal microstructures with fixed primaryαgrain sizes(0.8μm,2.4μm and 5.0μm),by changing the intercritical annealing temperature(T_(int)).By evaluating the tensile properties at room temperature,it was found that with increasing T_(int)(decreasing vol.%(α_(p))),the yield strength of bimodal microstructures monotonically increased,while the uniform elongation firstly increased with T_(int)until 910°C and then drastically decreased afterwards,thereby dividing the T_(int)into two regions,namely region I(830-910°C)and region II(910-970℃).The detailed deformation behaviors within the two regions were studied and compared,from the perspectives of strain distribution analysis,slip system analysis as well as dislocation analysis.For bimodal microstructures in region I,due to the much lower nano-hardness ofβ_(trans)thanα_(p),there was a clear strain partitioning between the two constituents as well as a strain gradient from theα_(p)/β_(trans)interface to the grain interior ofα_(p).This activated a large number of geometrically necessary dislocations(GNDs)near the interface,mostly with components,which contributed greatly to the extraordinary work-hardening abilities of bimodal microstructures in region I.With increasing T_(int),theα_(p)/β_(trans)interface length density gradually increased and so was the density of GNDs with components,which explained the continuous increase of uniform elongation with T_(int)in this region.For bimodal microstructures in region II,where the nano-hardness ofβ_(trans)andα_(p)were comparable,neither a clear strain-partitioning tendency nor a strain gradient across theα_(p)/β_(trans)interface was observed.Consequently,only statistically stored dislocations(SSDs)with component were activated insideα_(p).The absence of dislocations together with a decreased volume fraction ofα_(p)resulted into a dramatic loss of uniform elongation for bimodal microstructures in region II.
