Piezo-electric nano-positioning stages are being widely used in applications in which precision and accuracy in the order of nano, and high scanning speeds are paramount. This paper presents a Finite Element Analysis ...Piezo-electric nano-positioning stages are being widely used in applications in which precision and accuracy in the order of nano, and high scanning speeds are paramount. This paper presents a Finite Element Analysis (FEA) of the parallel piezo-flexural nano-positioning (PPNP) stages to investigate motion interference between their different axes. Cross-coupling is one of the significant contributors to undesirable runouts in the precision positioning of PPNP actuators. Using ABAQUS/CAE 2018 software, a 3D model of a PPNP stage was developed. The model consists of a central elastic body connected to a fixed frame through four flexural hinges. A cylindrical stack of multiple piezoelectric disks is placed between the moving central body and the fixed frame. Extensive simulations were carried out for three different friction coefficients in the piezoelectric disks’ contact surfaces, different frame materials, and different geometrical configurations of the stage and the hinges. As a result, it was observed that the primary root cause of the mechanical cross-coupling effect could be realized in the combination of the slip and rotation of the piezoelectric disks due to their frictional behavior with the stage moving in the tangential direction, concurrent with changes in the geometry of the stage.展开更多
The advancement of flexible memristors has significantly promoted the development of wearable electronic for emerging neuromorphic computing applications.Inspired by in-memory computing architecture of human brain,fle...The advancement of flexible memristors has significantly promoted the development of wearable electronic for emerging neuromorphic computing applications.Inspired by in-memory computing architecture of human brain,flexible memristors exhibit great application potential in emulating artificial synapses for highefficiency and low power consumption neuromorphic computing.This paper provides comprehensive overview of flexible memristors from perspectives of development history,material system,device structure,mechanical deformation method,device performance analysis,stress simulation during deformation,and neuromorphic computing applications.The recent advances in flexible electronics are summarized,including single device,device array and integration.The challenges and future perspectives of flexible memristor for neuromorphic computing are discussed deeply,paving the way for constructing wearable smart electronics and applications in large-scale neuromorphic computing and high-order intelligent robotics.展开更多
(NbZrHfTi)C high-entropy ceramics,as an emerging class of ultra-high-temperature materials,have garnered significant interest due to their unique multi-principal-element crystal structure and exceptional hightemperatu...(NbZrHfTi)C high-entropy ceramics,as an emerging class of ultra-high-temperature materials,have garnered significant interest due to their unique multi-principal-element crystal structure and exceptional hightemperature properties.This study systematically investigates the mechanical properties of(NbZrHfTi)C high-entropy ceramics by employing first-principles density functional theory,combined with the Debye-Grüneisen model,to explore the variations in their thermophysical properties with temperature(0–2000 K)and pressure(0–30 GPa).Thermodynamically,the calculated mixing enthalpy and Gibbs free energy confirm the feasibility of forming a stable single-phase solid solution in(NbZrHfTi)C.The calculated results of the elastic stiffness constant indicate that the material meets the mechanical stability criteria of the cubic crystal system,further confirming the structural stability.Through evaluation of key mechanical parameters—bulk modulus,shear modulus,Young’s modulus,and Poisson’s ratio—we provide comprehensive insight into the macro-mechanical behaviour of the material and its correlation with the underlying microstructure.Notably,compared to traditional binary carbides and their average properties,(NbZrHfTi)C exhibits higher Vickers hardness(Approximately 28.5 GPa)and fracture toughness(Approximately 3.4 MPa⋅m^(1/2)),which can be primarily attributed to the lattice distortion and solid-solution strengthening mechanism.The study also utilizes the quasi-harmonic approximation method to predict the material’s thermophysical properties,including Debye temperature(initial value around 563 K),thermal expansion coefficient(approximately 8.9×10^(−6) K−1 at 2000 K),and other key parameters such as heat capacity at constant volume.The results show that within the studied pressure and temperature ranges,(NbZrHfTi)C consistently maintains a stable phase structure and good thermomechanical properties.The thermal expansion coefficient increasing with temperature,while heat capacity approaches the Dulong-Petit limit at elevated temperatures.These findings underscore the potential of(NbZrHfTi)C applications in ultra-high temperature thermal protection systems,cutting tool coatings,and nuclear structural materials.展开更多
Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper,and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were investigated.In ad...Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper,and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were investigated.In addition,the joint formation mechanism was discussed,and the correlation between joint microstructure and mechanical performance was established.Results show that adding appropriate amount of In into the filler can significantly reduce the filler melting point and enhance the wettability of filler on diamond.When the brazing temperature is 750°C and the soaking time is 10 min,a uniformly dense braze seam with excellent metallurgical bonding can be obtained,and its average joint shear strength reaches 322 MPa.The lower brazing temperature can mitigate the risk of diamond graphitization and also reduce the residual stresses during joining.展开更多
Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusi...Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.展开更多
The microstructures and mechanical properties of Al-8.3Zn-3.3Cu-2.2Mg alloys prepared via hot extrusion and liquid forging methods were investigated.Results show that based on DEFORM simulation analysis,the optimal ho...The microstructures and mechanical properties of Al-8.3Zn-3.3Cu-2.2Mg alloys prepared via hot extrusion and liquid forging methods were investigated.Results show that based on DEFORM simulation analysis,the optimal hot extrusion parameters are determined as ingot initial temperature of 380°C and extrusion speed of 3 mm/s.The hot-extruded aluminum alloy after T6 heat treatment presents superior mechanical properties with yield strength of 519.6 MPa,ultimate tensile strength of 582.1 MPa,and elongation of 11.0%.Compared with the properties of gravity-cast and liquid-forged alloys,the yield strength of hot-extruded alloy increases by 30.8%and 4.9%,and the ultimate tensile strength improves by 43.5%and 10.2%,respectively.The significant improvement in tensile strength of the hot-extruded alloys is attributed to the elimination of casting defects and the refinement of matrix grain and eutectic phases.In addition,the hot-extruded alloy demonstrates superior plasticity compared with the liquid-forged alloy.This is because severe plastic deformation occurs during hot extrusion,which effectively breaks and disperses the eutectic phases,facilitating the dissolution and precipitation of the second phases and inhibiting the microcrack initiation.展开更多
Refractory high/medium-entropy alloys(RH/MEAs)are known for their outstanding performance at el-evated temperatures;however,they usually exhibit poor room-temperature plasticity,which can be at-tributed to the non-uni...Refractory high/medium-entropy alloys(RH/MEAs)are known for their outstanding performance at el-evated temperatures;however,they usually exhibit poor room-temperature plasticity,which can be at-tributed to the non-uniform deformation that occurs at room temperature.Once cracks nucleate,they will rapidly propagate into vertical splitting cracks.Here,we introduce multiple phases including FCC and HCP phases into the NbMoTa RMEA via appropriate addition of carbon.The results show that multiple-phase synergy effectively suppresses non-uniform deformation,thereby delaying the onset of vertical splitting cracks.An optimal combination of compressive strength-plasticity is achieved by the(NbMoTa)_(92.5)C_(7.5) alloy.The significant improvement in room-temperature mechanical properties can be attributed to its hierarchical microstructure:in the mesoscale,the BCC matrix is divided by eutectic structures;while at the microscale,the BCC matrix is further refined by abundant lath-like FCC precipitates.The FCC precip-itates contain high-density stacking faults,acting as a dislocation source under compressive loading.The HCP phase in the eutectic microstructures,in turn,acts as a strong barrier to dislocation movement and simultaneously increases the dislocation storage capacity.These findings open a new route to tailor the microstructure and mechanical properties of RH/MEAs.展开更多
The morphology and dimension of W phases play an important role in determining mechanical properties of Mg-RE-Zn(where RE denotes rare earth elements)alloys.In this study,theγ′platelet and W particle occurred in the...The morphology and dimension of W phases play an important role in determining mechanical properties of Mg-RE-Zn(where RE denotes rare earth elements)alloys.In this study,theγ′platelet and W particle occurred in the aged Mg-2Dy-0.5Zn(at.%)alloys were investigated by aberration-corrected scanning transmission electron microscopy.A novel formation mechanism of W phase was proposed,and its effects on the morphology and dimension of W particle,as well as mechanical properties of Mg-2Dy-0.5Zn alloys,were also discussed particularly.Different from other Mg-RE-Zn alloys,the nucleation and growth of W particle in Mg-Dy-Zn alloys mainly depend on the precipitatedγ′platelet.Primarily,a mass of Dy and Zn solute atoms concentrated nearγ′platelet or between two adjacentγ′platelets can meet the composition requirement of W particle nucleation.Next,the smaller interfacial mismatch between W andγ′facilitates the nucleation and growth of W particle.Thirdly,the growth of W particle can be achieved by consuming the surroundingγ′platelets.The nucleation and growth mechanisms make W particles exhibit rectangular or leaf-like and remain at the nanoscale.The coexistence ofγ′platelets and nanoscale W particles,and some better interfacial relationships between phases,lead to a high strength-ductility synergy of alloy.The findings may provide some fundamental guidelines for the microstructure design and optimization of new-type Mg-based alloys.展开更多
Irregular bone scaffolds fabricated using the Voronoi tessellation method resemble the morphology and properties of human cancellous bones.This has become a prominent topic in bone tissue engineering research in recen...Irregular bone scaffolds fabricated using the Voronoi tessellation method resemble the morphology and properties of human cancellous bones.This has become a prominent topic in bone tissue engineering research in recent years.However,studies on the radial-gradient design of irregular bionic scaffolds are limited.Therefore,this study aims to develop a radial-gradient structure similar to that of natural long bones,enhancing the development of bionic bone scaffolds.A novel gradient method was adopted to maintain constant porosity,control the seed site-specific distribution within the irregular porous structure,and vary the strut diameter to generate radial gradients.The irregular scaffolds were compared with four conventional scaffolds(cube,pillar BCC,vintiles,and diamond)in terms of permeability,stress concentration characteristics,and mechanical properties.The results indicate that the radial-gradient irregular porous structure boasts the widest permeability range and superior stress distribution compared to conventional scaffolds.With an elastic modulus ranging from 4.20 GPa to 22.96 GPa and a yield strength between 68.37 MPa and 149.40 MPa,it meets bone implant performance requirements and demonstrates significant application potential.展开更多
In cold regions,slope rocks are inevitably impacted by freeze-thaw,dry-wet cycles and their alternating actions,leading to strength weakening and pore degradation.In this study,the mechanical and microstructural prope...In cold regions,slope rocks are inevitably impacted by freeze-thaw,dry-wet cycles and their alternating actions,leading to strength weakening and pore degradation.In this study,the mechanical and microstructural properties of schist subjected to four conditions were investigated:freeze-thaw cycles in air(FTA),freeze-thaw cycles in water(FTW),dry-wet cycles(DW),and dry-wet-freeze-thaw cycles(DWFT).Uniaxial compressive strength(UCS),water absorption,ultrasonication,low-field nuclear magnetic resonance,and scanning electron microscopy analyses were conducted.The integrity attenuation characteristics of the longitudinal wave velocity,UCS,and elastic modulus were analyzed.The results showed that liquid water emerged as a critical factor in reducing the brittleness of schist.The attenuation function model accurately described the peak stress and static elastic modulus of schist in various media(R2>0.97).Different media affected the schist deterioration and half-life,with the FTW-immersed samples having a half-life of 28 cycles.Furthermore,the longitudinal wave velocity decreased as the number of cycles increased,with the FTW showing the most significant reduction and having the shortest half-life of 208 cycles.Moreover,the damage variables of compressive strength and elastic modulus increased with the number of cycles.After 40 cycles,the schist exposed to FTW exhibited the highest damage variables and saturated water content.展开更多
The performances of magnesium alloys remain insufficient to further enhance the application potential of ultralight magnesium alloys.In this work,a Mg-8Li-3Y-2Zn alloy was prepared through vacuum melting and subsequent...The performances of magnesium alloys remain insufficient to further enhance the application potential of ultralight magnesium alloys.In this work,a Mg-8Li-3Y-2Zn alloy was prepared through vacuum melting and subsequent heat treatment at 300,450,and 500°C.The material properties of the resulting samples were assessed through microstructural observation,tensile testing,electrical conductivity measurements,and electromagnetic shielding effectiveness(EMI-SE)testing.The influence of the Mg-8Li-3Y-2Zn alloy microstructure on its mechanical and electromagnetic shielding properties in different states was investigated.It was found that the as-cast alloy containsα-Mg,β-Li,Mg_(3)Zn_(3)Y_(2),and Mg_(12)ZnY phases.Following heat treatment at 500℃(HT500),the blockα-Mg phase transformedfine needle-shapes,its tensile strength increased to 263.7 MPa,and its elongation reached 45.3%.The mechanical properties of the alloy were significantly improved by the synergistic effects imparted by the needle-shapedα-Mg phase,solid solution strengthening,and precipitation strengthening.The addition of Y and Zn improved the EMI-SE of Mg-8Li-1Zn alloy,wherein the HT500 sample exhibits the highest SE,maintaining a value of 106.7–76.9 dB in the frequency range of 30–4500 MHz;this performance has rarely been reported for electromagnetically shielded alloys.This effect was mainly attributed to the multiple reflections of electromagnetic waves caused by the severe impedance mismatch of the abundant phase boundaries,which were in turn provided by the dual-phase(α/β)and secondary phases.Furthermore,the presence of nano-precipitation was also believed to enhance the absorption of electromagnetic waves.展开更多
A chromium(II)-catalyzed reduction cross coupling reaction was reported.This reaction utilizes inexpensive and readily available chromium dichloride as a catalyst and 4,4'-di-tert-butyl-bipyridine as a ligand to a...A chromium(II)-catalyzed reduction cross coupling reaction was reported.This reaction utilizes inexpensive and readily available chromium dichloride as a catalyst and 4,4'-di-tert-butyl-bipyridine as a ligand to achieve reduction cross coupling between trifluoromethyl olefins and alkyl bromides under mild conditions,effectively synthesizing difluoroalkene derivatives.This reaction exhibits good substrate universality and is compatible with multiple important functional groups,providing a concise synthetic pathway for constructing conjugated difluoroalkenes containing allyl difluoromethylene structural units.Preliminary mechanistic experiments indicate that alkyl bromides first undergo a reduction process to generate corresponding alkyl radicals,followed by addition to trifluoromethyl olefins.After binding with Cr(II),they undergo aβ-fluorine elimination process to generate difluoroalkenes.展开更多
High-entropy materials possess high hardness and strong wear resistance,yet the key bottleneck for their practical applications is the poor corrosion resistance in harsh environments.In this work,the high-entropy nitr...High-entropy materials possess high hardness and strong wear resistance,yet the key bottleneck for their practical applications is the poor corrosion resistance in harsh environments.In this work,the high-entropy nitride(HEN)coatings of(MoNbTaTiZr)1-x Nx(x=0-0.47)were fabricated using a hybrid di-rect current magnetron sputtering technique.The research focus was dedicated to the effect of nitrogen content on the microstructure,mechanical and electrochemical properties.The results showed that the as-deposited coatings exhibited a typical body-centered cubic(BCC)structure without nitrogen,while the amorphous matrix with face-centered cubic(FCC)nanocrystalline grain was observed at x=0.17.Further increasing x in the range of 0.35-0.47 caused the appearance of polycrystalline FCC phase in structure.Compared with the MoNbTaTiZr metallic coating,the coating containing nitrogen favored the high hard-ness around 13.7-32.4 GPa,accompanied by excellent tolerance both against elastic and plastic deforma-tion.Furthermore,such N-containing coatings yielded a low corrosion current density of about 10−8-10−7 A/cm^(2) and high electrochemical impedance of 10^(6)Ωcm^(2) in 3.5 wt.%NaCl solution,indicating the supe-rior corrosion resistance.The reason for the enhanced electrochemical behavior could be ascribed to the spontaneous formation of protective passive layers over the coating surface,which consisted of the domi-nated multi-elemental oxides in chemical stability.Particularly,noted that the(MoNbTaTiZr)_(0.83) N0.17 coat-ing displayed the highest hardness of 32.4±2.6 GPa and H/E ratio at 0.09,together with remarkable cor-rosion resistance,proposing the strongest capability for harsh-environmental applications required both good anti-wear and anti-corrosion performance.展开更多
The characterization techniques were employed like transmission electron microscope,X-ray diffraction and microstructural characterization to investigate microstructural evolution and impact of precipitate-phase preci...The characterization techniques were employed like transmission electron microscope,X-ray diffraction and microstructural characterization to investigate microstructural evolution and impact of precipitate-phase precipitation on strength and toughness of a self-developed 32Si_(2)CrNi_(2)MoVNb steel during the quenching and tempering process.Research outputs indicated that the steel microstructure under the quenching state could be composed of martensite with a high dislocation density,a small amount of residual austenite,and many dispersed spherical MC carbides.In details,after tempering at 200℃,fine needle-shapedε-carbides would precipitate,which may improve yield strength and toughness of the steel.However,as compared to that after tempering at 200℃,the average length of needle-shapedε-carbides was found to increase to 144.1±4 from 134.1±3 nm after tempering at 340℃.As a result,the yield strength may increase to 1505±40 MPa,and the impact absorption energy(V-notch)may also decrease.Moreover,after tempering at 450℃,thoseε-carbides in the steel may transform into coarse rod-shaped cementite,and dislocation recoveries at such high tempering temperature may lead to decrease of strength and toughness of the steel.Finally,the following properties could be obtained:a yield strength of 1440±35 MPa,an ultimate tensile strength of 1864±50 MPa and an impact absorption energy of 45.9±4 J,by means of rational composition design and microstructural control.展开更多
Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation,microstructure,and mechanical properties of the joints.Results show that under different welding parameters,with ...Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation,microstructure,and mechanical properties of the joints.Results show that under different welding parameters,with the decrease in welding heat input,the weld surface is smoother.The Ti/Al joint interface is flat without obvious Ti and Al mixed structure,and the hook structure is not formed under optimal parameters.Due to the enhanced breaking effect of the stirring head,the hook structural defects and intermetallic compounds are more likely to form at the Ti/Al interface at high rotational speed of 1000 r/min,thereby deteriorating the mechanical properties of joints.Decreasing the heat input is beneficial to hardness enhancement of the aluminum alloy in the weld nugget zone.Under the optimal parameters of rotation speed of 800 r/min and welding speed of 120 mm/min,the maximum tensile shear strength of joint is 289 N/mm.展开更多
Cells,tissues,and organs are constantly subjected to the action of mechanical forces from the extracellular environment-and the nervous system is no exception.Cell-intrinsic properties such as membrane lipid compositi...Cells,tissues,and organs are constantly subjected to the action of mechanical forces from the extracellular environment-and the nervous system is no exception.Cell-intrinsic properties such as membrane lipid composition,abundance of mechanosensors,and cytoskeletal dynamics make cells more or less likely to sense these forces.Intrinsic and extrinsic cues are integrated by cells and this combined information determines the rate and dynamics of membrane protrusion growth or retraction(Yamada and Sixt,2019).Cell protrusions are extensions of the plasma membrane that play crucial roles in diverse contexts such as cell migration and neuronal synapse formation.In the nervous system,neurons are highly dynamic cells that can change the size and number of their pre-and postsynaptic elements(called synaptic boutons and dendritic spines,respectively),in response to changes in the levels of synaptic activity through a process called plasticity.Synaptic plasticity is a hallmark of the nervous system and is present throughout our lives,being required for functions like memory formation or the learning of new motor skills(Minegishi et al.,2023;Pillai and Franze,2024).展开更多
Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-c...Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-coupling reactions are among the most straightforward and effective methods for synthesizing chiral carbonyl compounds, including esters, amides, and ketones. The advances in asymmetric carbonylative cross-coupling reactions using various O-, N-, C-, and S-containing nucleophiles or electrophiles over the past decade are summarized.展开更多
The occurrence of top-down(TD)cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service.A coupled simulation model integrating the finite difference method(FDM)and di...The occurrence of top-down(TD)cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service.A coupled simulation model integrating the finite difference method(FDM)and discrete element method(DEM)was employed to investigate the mechanical behavior of asphalt pavement containing a pre-existing TD crack.The mesoscopic parameters of the model were calibrated based on the mixture modulus and the static mechanical response on the MLS66 test road.Finally,an analysis was performed to assess how variations in TD crack depth and longitudinal length affect the distribution patterns of transverse tensile stress,vertical shear stress,and vertical compressive stress.The results indicate that the vertical propagation of TD crack significantly increases both the tensile stress value and range on the middle surface,while the longitudinal development of TD crack has minimal impact.This phenomenon may result in more severe fatigue failure on the middle surface.With the vertical and longitudinal development of TD crack,the vertical shear stress and compressive stress show obvious"two-stage"characteristics.When the crack's vertical length reaches 40 mm,there is a sharp increase in stress on the upper surface.As the crack continues to propagate vertically,the growth of stress on the upper surface becomes negligible,while the stress in the middle and lower layers increased significantly.Conversely,for longitudinal development of TD crack,any changes in stress are insignificant when their length is less than 180 mm;however,as they continue to develop longitudinally beyond this threshold,there is a sharp increase in stress levels.These findings hold great significance for understanding pavement structure deterioration and maintenance behavior associated with TD crack.展开更多
Hot isostatic pressing (HIP) temperature has a significant impact on the service performance of powder metallurgy titanium alloys. In this study, a high-temperature titanium alloy, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si, was prep...Hot isostatic pressing (HIP) temperature has a significant impact on the service performance of powder metallurgy titanium alloys. In this study, a high-temperature titanium alloy, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si, was prepared under different HIP temperatures (880–1000℃), and the microstructural evolution and mechanical properties were systematically investigated. The results demonstrated that the HIPed alloys were predominantly composed of more than 80 vol.% α phase and a small amount of β phase, and their phase compositions were basically unaffected by the HIP temperatures. Under the typical single-temperature-maintained HIP (STM-HIP) regime, the microstructure of alloy significantly coarsened as the HIP temperature increased, and the alloy strength exhibited an obvious linear negative correlation with the HIP temperature. On the basis of Hall–Petch relation, the prediction model of grain size was established, and the mathematical equation between HIP temperature and grain size (d=M(T_(HIP-N)^(-2))) was deduced. Furthermore, a possible evolution mechanism of microstructure was proposed, which could be divided into the decomposition of initial α′ martensite for as-received powder, formation of the globular α grains in prior particle boundaries (PPBs) region, and precipitation of the platelet α grains in non-PPBs region. For these alloys prepared by the dual-temperature-maintained HIP (DTM-HIP) regime, although their tensile properties were comparable to that of alloy prepared by STM-HIP regime with same high-temperature holding stage, higher proportion of globular α grains occurred due to more recrystallization nucleation during the low-temperature holding stage, which probably provided a solution for improving the dynamic service performance of HIPed alloys.展开更多
Scar formation resulting from burns or severe trauma can significantly compromise the structural integrity of skin and lead to permanent loss of skin appendages,ultimately impairing its normal physiological function.A...Scar formation resulting from burns or severe trauma can significantly compromise the structural integrity of skin and lead to permanent loss of skin appendages,ultimately impairing its normal physiological function.Accumulating evidence underscores the potential of targeted modulation of mechanical cues to enhance skin regeneration,promoting scarless repair by influencing the extracellular microenvironment and driving the phenotypic transitions.The field of skin repair and skin appendage regeneration has witnessed remarkable advancements in the utilization of biomaterials with distinct physical properties.However,a comprehensive understanding of the underlying mechanisms remains somewhat elusive,limiting the broader application of these innovations.In this review,we present two promising biomaterial-based mechanical approaches aimed at bolstering the regenerative capacity of compromised skin.The first approach involves leveraging biomaterials with specific biophysical properties to create an optimal scarless environment that supports cellular activities essential for regeneration.The second approach centers on harnessing mechanical forces exerted by biomaterials to enhance cellular plasticity,facilitating efficient cellular reprogramming and,consequently,promoting the regeneration of skin appendages.In summary,the manipulation of mechanical cues using biomaterial-based strategies holds significant promise as a supplementary approach for achieving scarless wound healing,coupled with the restoration of multiple skin appendage functions.展开更多
文摘Piezo-electric nano-positioning stages are being widely used in applications in which precision and accuracy in the order of nano, and high scanning speeds are paramount. This paper presents a Finite Element Analysis (FEA) of the parallel piezo-flexural nano-positioning (PPNP) stages to investigate motion interference between their different axes. Cross-coupling is one of the significant contributors to undesirable runouts in the precision positioning of PPNP actuators. Using ABAQUS/CAE 2018 software, a 3D model of a PPNP stage was developed. The model consists of a central elastic body connected to a fixed frame through four flexural hinges. A cylindrical stack of multiple piezoelectric disks is placed between the moving central body and the fixed frame. Extensive simulations were carried out for three different friction coefficients in the piezoelectric disks’ contact surfaces, different frame materials, and different geometrical configurations of the stage and the hinges. As a result, it was observed that the primary root cause of the mechanical cross-coupling effect could be realized in the combination of the slip and rotation of the piezoelectric disks due to their frictional behavior with the stage moving in the tangential direction, concurrent with changes in the geometry of the stage.
基金supported by the NSFC(12474071)Natural Science Foundation of Shandong Province(ZR2024YQ051)+5 种基金Open Research Fund of State Key Laboratory of Materials for Integrated Circuits(SKLJC-K2024-12)the Shanghai Sailing Program(23YF1402200,23YF1402400)Natural Science Foundation of Jiangsu Province(BK20240424)Taishan Scholar Foundation of Shandong Province(tsqn202408006)Young Talent of Lifting engineering for Science and Technology in Shandong,China(SDAST2024QTB002)the Qilu Young Scholar Program of Shandong University.
文摘The advancement of flexible memristors has significantly promoted the development of wearable electronic for emerging neuromorphic computing applications.Inspired by in-memory computing architecture of human brain,flexible memristors exhibit great application potential in emulating artificial synapses for highefficiency and low power consumption neuromorphic computing.This paper provides comprehensive overview of flexible memristors from perspectives of development history,material system,device structure,mechanical deformation method,device performance analysis,stress simulation during deformation,and neuromorphic computing applications.The recent advances in flexible electronics are summarized,including single device,device array and integration.The challenges and future perspectives of flexible memristor for neuromorphic computing are discussed deeply,paving the way for constructing wearable smart electronics and applications in large-scale neuromorphic computing and high-order intelligent robotics.
基金supported by the National Natural Science Foundation of China(Nos.92166105 and 52005053)High-Tech Industry Science and Technology Innovation Leading Program of Hunan Province(No.2020GK2085)the Science and Technology Innovation Program of Hunan Province(No.2021RC3096).
文摘(NbZrHfTi)C high-entropy ceramics,as an emerging class of ultra-high-temperature materials,have garnered significant interest due to their unique multi-principal-element crystal structure and exceptional hightemperature properties.This study systematically investigates the mechanical properties of(NbZrHfTi)C high-entropy ceramics by employing first-principles density functional theory,combined with the Debye-Grüneisen model,to explore the variations in their thermophysical properties with temperature(0–2000 K)and pressure(0–30 GPa).Thermodynamically,the calculated mixing enthalpy and Gibbs free energy confirm the feasibility of forming a stable single-phase solid solution in(NbZrHfTi)C.The calculated results of the elastic stiffness constant indicate that the material meets the mechanical stability criteria of the cubic crystal system,further confirming the structural stability.Through evaluation of key mechanical parameters—bulk modulus,shear modulus,Young’s modulus,and Poisson’s ratio—we provide comprehensive insight into the macro-mechanical behaviour of the material and its correlation with the underlying microstructure.Notably,compared to traditional binary carbides and their average properties,(NbZrHfTi)C exhibits higher Vickers hardness(Approximately 28.5 GPa)and fracture toughness(Approximately 3.4 MPa⋅m^(1/2)),which can be primarily attributed to the lattice distortion and solid-solution strengthening mechanism.The study also utilizes the quasi-harmonic approximation method to predict the material’s thermophysical properties,including Debye temperature(initial value around 563 K),thermal expansion coefficient(approximately 8.9×10^(−6) K−1 at 2000 K),and other key parameters such as heat capacity at constant volume.The results show that within the studied pressure and temperature ranges,(NbZrHfTi)C consistently maintains a stable phase structure and good thermomechanical properties.The thermal expansion coefficient increasing with temperature,while heat capacity approaches the Dulong-Petit limit at elevated temperatures.These findings underscore the potential of(NbZrHfTi)C applications in ultra-high temperature thermal protection systems,cutting tool coatings,and nuclear structural materials.
基金National MCF Energy R&D Program(2019YFE03100400)。
文摘Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper,and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were investigated.In addition,the joint formation mechanism was discussed,and the correlation between joint microstructure and mechanical performance was established.Results show that adding appropriate amount of In into the filler can significantly reduce the filler melting point and enhance the wettability of filler on diamond.When the brazing temperature is 750°C and the soaking time is 10 min,a uniformly dense braze seam with excellent metallurgical bonding can be obtained,and its average joint shear strength reaches 322 MPa.The lower brazing temperature can mitigate the risk of diamond graphitization and also reduce the residual stresses during joining.
基金supported by the National Science and Technology Major Project,China(No.2019-VI-0004-0118)the National Natural Science Foundation of China(No.51771152)the National Key R&D Program of China(No.2018YFB1106800)。
文摘Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.
基金Natural Science Foundation of Shandong Province of China(ZR2023QE193)。
文摘The microstructures and mechanical properties of Al-8.3Zn-3.3Cu-2.2Mg alloys prepared via hot extrusion and liquid forging methods were investigated.Results show that based on DEFORM simulation analysis,the optimal hot extrusion parameters are determined as ingot initial temperature of 380°C and extrusion speed of 3 mm/s.The hot-extruded aluminum alloy after T6 heat treatment presents superior mechanical properties with yield strength of 519.6 MPa,ultimate tensile strength of 582.1 MPa,and elongation of 11.0%.Compared with the properties of gravity-cast and liquid-forged alloys,the yield strength of hot-extruded alloy increases by 30.8%and 4.9%,and the ultimate tensile strength improves by 43.5%and 10.2%,respectively.The significant improvement in tensile strength of the hot-extruded alloys is attributed to the elimination of casting defects and the refinement of matrix grain and eutectic phases.In addition,the hot-extruded alloy demonstrates superior plasticity compared with the liquid-forged alloy.This is because severe plastic deformation occurs during hot extrusion,which effectively breaks and disperses the eutectic phases,facilitating the dissolution and precipitation of the second phases and inhibiting the microcrack initiation.
基金financial support from the Na-tional Natural Science Foundation of China(No.52231006)National Key Research and Development Program of China(No.2017YFB0702003)the National Natural Science Foundation of China(No.51871217).
文摘Refractory high/medium-entropy alloys(RH/MEAs)are known for their outstanding performance at el-evated temperatures;however,they usually exhibit poor room-temperature plasticity,which can be at-tributed to the non-uniform deformation that occurs at room temperature.Once cracks nucleate,they will rapidly propagate into vertical splitting cracks.Here,we introduce multiple phases including FCC and HCP phases into the NbMoTa RMEA via appropriate addition of carbon.The results show that multiple-phase synergy effectively suppresses non-uniform deformation,thereby delaying the onset of vertical splitting cracks.An optimal combination of compressive strength-plasticity is achieved by the(NbMoTa)_(92.5)C_(7.5) alloy.The significant improvement in room-temperature mechanical properties can be attributed to its hierarchical microstructure:in the mesoscale,the BCC matrix is divided by eutectic structures;while at the microscale,the BCC matrix is further refined by abundant lath-like FCC precipitates.The FCC precip-itates contain high-density stacking faults,acting as a dislocation source under compressive loading.The HCP phase in the eutectic microstructures,in turn,acts as a strong barrier to dislocation movement and simultaneously increases the dislocation storage capacity.These findings open a new route to tailor the microstructure and mechanical properties of RH/MEAs.
基金supported by Natural Science Foundation of Liaoning Province of China under Grant No.2020-MS-085。
文摘The morphology and dimension of W phases play an important role in determining mechanical properties of Mg-RE-Zn(where RE denotes rare earth elements)alloys.In this study,theγ′platelet and W particle occurred in the aged Mg-2Dy-0.5Zn(at.%)alloys were investigated by aberration-corrected scanning transmission electron microscopy.A novel formation mechanism of W phase was proposed,and its effects on the morphology and dimension of W particle,as well as mechanical properties of Mg-2Dy-0.5Zn alloys,were also discussed particularly.Different from other Mg-RE-Zn alloys,the nucleation and growth of W particle in Mg-Dy-Zn alloys mainly depend on the precipitatedγ′platelet.Primarily,a mass of Dy and Zn solute atoms concentrated nearγ′platelet or between two adjacentγ′platelets can meet the composition requirement of W particle nucleation.Next,the smaller interfacial mismatch between W andγ′facilitates the nucleation and growth of W particle.Thirdly,the growth of W particle can be achieved by consuming the surroundingγ′platelets.The nucleation and growth mechanisms make W particles exhibit rectangular or leaf-like and remain at the nanoscale.The coexistence ofγ′platelets and nanoscale W particles,and some better interfacial relationships between phases,lead to a high strength-ductility synergy of alloy.The findings may provide some fundamental guidelines for the microstructure design and optimization of new-type Mg-based alloys.
基金the National Natural Science Foundation of China(No.52165026)。
文摘Irregular bone scaffolds fabricated using the Voronoi tessellation method resemble the morphology and properties of human cancellous bones.This has become a prominent topic in bone tissue engineering research in recent years.However,studies on the radial-gradient design of irregular bionic scaffolds are limited.Therefore,this study aims to develop a radial-gradient structure similar to that of natural long bones,enhancing the development of bionic bone scaffolds.A novel gradient method was adopted to maintain constant porosity,control the seed site-specific distribution within the irregular porous structure,and vary the strut diameter to generate radial gradients.The irregular scaffolds were compared with four conventional scaffolds(cube,pillar BCC,vintiles,and diamond)in terms of permeability,stress concentration characteristics,and mechanical properties.The results indicate that the radial-gradient irregular porous structure boasts the widest permeability range and superior stress distribution compared to conventional scaffolds.With an elastic modulus ranging from 4.20 GPa to 22.96 GPa and a yield strength between 68.37 MPa and 149.40 MPa,it meets bone implant performance requirements and demonstrates significant application potential.
基金supported by the National Natural Science Foundation of China(Nos.42171108 and 42101136)Sichuan Science and Technology Program(Nos.2024NSFSC2007 and2025YFHZ0273)Natural Science Starting Project of SWPU(No.2024QHZ029)。
文摘In cold regions,slope rocks are inevitably impacted by freeze-thaw,dry-wet cycles and their alternating actions,leading to strength weakening and pore degradation.In this study,the mechanical and microstructural properties of schist subjected to four conditions were investigated:freeze-thaw cycles in air(FTA),freeze-thaw cycles in water(FTW),dry-wet cycles(DW),and dry-wet-freeze-thaw cycles(DWFT).Uniaxial compressive strength(UCS),water absorption,ultrasonication,low-field nuclear magnetic resonance,and scanning electron microscopy analyses were conducted.The integrity attenuation characteristics of the longitudinal wave velocity,UCS,and elastic modulus were analyzed.The results showed that liquid water emerged as a critical factor in reducing the brittleness of schist.The attenuation function model accurately described the peak stress and static elastic modulus of schist in various media(R2>0.97).Different media affected the schist deterioration and half-life,with the FTW-immersed samples having a half-life of 28 cycles.Furthermore,the longitudinal wave velocity decreased as the number of cycles increased,with the FTW showing the most significant reduction and having the shortest half-life of 208 cycles.Moreover,the damage variables of compressive strength and elastic modulus increased with the number of cycles.After 40 cycles,the schist exposed to FTW exhibited the highest damage variables and saturated water content.
基金supported by the National Natural Sci-ence Foundation of China[No.51564032]Yunnan Provin-cial Department of Education Science Research Fund Project[KKPH202132005]the Analysis and Testing Founda-tion of Kunming University of Science and Technology[2022M20212130086].
文摘The performances of magnesium alloys remain insufficient to further enhance the application potential of ultralight magnesium alloys.In this work,a Mg-8Li-3Y-2Zn alloy was prepared through vacuum melting and subsequent heat treatment at 300,450,and 500°C.The material properties of the resulting samples were assessed through microstructural observation,tensile testing,electrical conductivity measurements,and electromagnetic shielding effectiveness(EMI-SE)testing.The influence of the Mg-8Li-3Y-2Zn alloy microstructure on its mechanical and electromagnetic shielding properties in different states was investigated.It was found that the as-cast alloy containsα-Mg,β-Li,Mg_(3)Zn_(3)Y_(2),and Mg_(12)ZnY phases.Following heat treatment at 500℃(HT500),the blockα-Mg phase transformedfine needle-shapes,its tensile strength increased to 263.7 MPa,and its elongation reached 45.3%.The mechanical properties of the alloy were significantly improved by the synergistic effects imparted by the needle-shapedα-Mg phase,solid solution strengthening,and precipitation strengthening.The addition of Y and Zn improved the EMI-SE of Mg-8Li-1Zn alloy,wherein the HT500 sample exhibits the highest SE,maintaining a value of 106.7–76.9 dB in the frequency range of 30–4500 MHz;this performance has rarely been reported for electromagnetically shielded alloys.This effect was mainly attributed to the multiple reflections of electromagnetic waves caused by the severe impedance mismatch of the abundant phase boundaries,which were in turn provided by the dual-phase(α/β)and secondary phases.Furthermore,the presence of nano-precipitation was also believed to enhance the absorption of electromagnetic waves.
文摘A chromium(II)-catalyzed reduction cross coupling reaction was reported.This reaction utilizes inexpensive and readily available chromium dichloride as a catalyst and 4,4'-di-tert-butyl-bipyridine as a ligand to achieve reduction cross coupling between trifluoromethyl olefins and alkyl bromides under mild conditions,effectively synthesizing difluoroalkene derivatives.This reaction exhibits good substrate universality and is compatible with multiple important functional groups,providing a concise synthetic pathway for constructing conjugated difluoroalkenes containing allyl difluoromethylene structural units.Preliminary mechanistic experiments indicate that alkyl bromides first undergo a reduction process to generate corresponding alkyl radicals,followed by addition to trifluoromethyl olefins.After binding with Cr(II),they undergo aβ-fluorine elimination process to generate difluoroalkenes.
基金supported by the National Science Fund for Distinguished Young Scholars of China(No.52025014)Zhejiang Provincial Natural Science Foundation of China(Nos.LZJWY23E090001 and LD24E010003)the Natural Science Foundation of Ningbo(No.2022J305).
文摘High-entropy materials possess high hardness and strong wear resistance,yet the key bottleneck for their practical applications is the poor corrosion resistance in harsh environments.In this work,the high-entropy nitride(HEN)coatings of(MoNbTaTiZr)1-x Nx(x=0-0.47)were fabricated using a hybrid di-rect current magnetron sputtering technique.The research focus was dedicated to the effect of nitrogen content on the microstructure,mechanical and electrochemical properties.The results showed that the as-deposited coatings exhibited a typical body-centered cubic(BCC)structure without nitrogen,while the amorphous matrix with face-centered cubic(FCC)nanocrystalline grain was observed at x=0.17.Further increasing x in the range of 0.35-0.47 caused the appearance of polycrystalline FCC phase in structure.Compared with the MoNbTaTiZr metallic coating,the coating containing nitrogen favored the high hard-ness around 13.7-32.4 GPa,accompanied by excellent tolerance both against elastic and plastic deforma-tion.Furthermore,such N-containing coatings yielded a low corrosion current density of about 10−8-10−7 A/cm^(2) and high electrochemical impedance of 10^(6)Ωcm^(2) in 3.5 wt.%NaCl solution,indicating the supe-rior corrosion resistance.The reason for the enhanced electrochemical behavior could be ascribed to the spontaneous formation of protective passive layers over the coating surface,which consisted of the domi-nated multi-elemental oxides in chemical stability.Particularly,noted that the(MoNbTaTiZr)_(0.83) N0.17 coat-ing displayed the highest hardness of 32.4±2.6 GPa and H/E ratio at 0.09,together with remarkable cor-rosion resistance,proposing the strongest capability for harsh-environmental applications required both good anti-wear and anti-corrosion performance.
基金the National Natural Science Foundation of China(Key Program)(52031004).
文摘The characterization techniques were employed like transmission electron microscope,X-ray diffraction and microstructural characterization to investigate microstructural evolution and impact of precipitate-phase precipitation on strength and toughness of a self-developed 32Si_(2)CrNi_(2)MoVNb steel during the quenching and tempering process.Research outputs indicated that the steel microstructure under the quenching state could be composed of martensite with a high dislocation density,a small amount of residual austenite,and many dispersed spherical MC carbides.In details,after tempering at 200℃,fine needle-shapedε-carbides would precipitate,which may improve yield strength and toughness of the steel.However,as compared to that after tempering at 200℃,the average length of needle-shapedε-carbides was found to increase to 144.1±4 from 134.1±3 nm after tempering at 340℃.As a result,the yield strength may increase to 1505±40 MPa,and the impact absorption energy(V-notch)may also decrease.Moreover,after tempering at 450℃,thoseε-carbides in the steel may transform into coarse rod-shaped cementite,and dislocation recoveries at such high tempering temperature may lead to decrease of strength and toughness of the steel.Finally,the following properties could be obtained:a yield strength of 1440±35 MPa,an ultimate tensile strength of 1864±50 MPa and an impact absorption energy of 45.9±4 J,by means of rational composition design and microstructural control.
基金National Natural Science Foundation of China(52275349)Key Research and Development Program of Shandong Province(2021ZLGX01)。
文摘Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation,microstructure,and mechanical properties of the joints.Results show that under different welding parameters,with the decrease in welding heat input,the weld surface is smoother.The Ti/Al joint interface is flat without obvious Ti and Al mixed structure,and the hook structure is not formed under optimal parameters.Due to the enhanced breaking effect of the stirring head,the hook structural defects and intermetallic compounds are more likely to form at the Ti/Al interface at high rotational speed of 1000 r/min,thereby deteriorating the mechanical properties of joints.Decreasing the heat input is beneficial to hardness enhancement of the aluminum alloy in the weld nugget zone.Under the optimal parameters of rotation speed of 800 r/min and welding speed of 120 mm/min,the maximum tensile shear strength of joint is 289 N/mm.
基金supported by PTDC-01778/2022-NeuroDev3D,iNOVA4Health(UIDB/04462/2020 and UIDP/04462/2020)LS4FUTURE(LA/P/0087/2020)。
文摘Cells,tissues,and organs are constantly subjected to the action of mechanical forces from the extracellular environment-and the nervous system is no exception.Cell-intrinsic properties such as membrane lipid composition,abundance of mechanosensors,and cytoskeletal dynamics make cells more or less likely to sense these forces.Intrinsic and extrinsic cues are integrated by cells and this combined information determines the rate and dynamics of membrane protrusion growth or retraction(Yamada and Sixt,2019).Cell protrusions are extensions of the plasma membrane that play crucial roles in diverse contexts such as cell migration and neuronal synapse formation.In the nervous system,neurons are highly dynamic cells that can change the size and number of their pre-and postsynaptic elements(called synaptic boutons and dendritic spines,respectively),in response to changes in the levels of synaptic activity through a process called plasticity.Synaptic plasticity is a hallmark of the nervous system and is present throughout our lives,being required for functions like memory formation or the learning of new motor skills(Minegishi et al.,2023;Pillai and Franze,2024).
文摘Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-coupling reactions are among the most straightforward and effective methods for synthesizing chiral carbonyl compounds, including esters, amides, and ketones. The advances in asymmetric carbonylative cross-coupling reactions using various O-, N-, C-, and S-containing nucleophiles or electrophiles over the past decade are summarized.
基金supported by National Key R&D Program of China(Grant No.2021YFB2601200)Open Fund of National Engineering Research Center of Highway Maintenance Technology(Changsha University of Science&Technology)(No.kfj230207).
文摘The occurrence of top-down(TD)cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service.A coupled simulation model integrating the finite difference method(FDM)and discrete element method(DEM)was employed to investigate the mechanical behavior of asphalt pavement containing a pre-existing TD crack.The mesoscopic parameters of the model were calibrated based on the mixture modulus and the static mechanical response on the MLS66 test road.Finally,an analysis was performed to assess how variations in TD crack depth and longitudinal length affect the distribution patterns of transverse tensile stress,vertical shear stress,and vertical compressive stress.The results indicate that the vertical propagation of TD crack significantly increases both the tensile stress value and range on the middle surface,while the longitudinal development of TD crack has minimal impact.This phenomenon may result in more severe fatigue failure on the middle surface.With the vertical and longitudinal development of TD crack,the vertical shear stress and compressive stress show obvious"two-stage"characteristics.When the crack's vertical length reaches 40 mm,there is a sharp increase in stress on the upper surface.As the crack continues to propagate vertically,the growth of stress on the upper surface becomes negligible,while the stress in the middle and lower layers increased significantly.Conversely,for longitudinal development of TD crack,any changes in stress are insignificant when their length is less than 180 mm;however,as they continue to develop longitudinally beyond this threshold,there is a sharp increase in stress levels.These findings hold great significance for understanding pavement structure deterioration and maintenance behavior associated with TD crack.
基金support from CAS Project for Young Scientists in Basic Research(YSBR-025)and the Technology Innovation(RCJJ-145-24-39)R.P.Guo acknowledges the financial support from the National Natural Science Foundation of China(No.52401104)+1 种基金the Fundamental Research Program of Shanxi Province(No.202203021221072)the China Postdoctoral Science Foundation(No.2024M753298).
文摘Hot isostatic pressing (HIP) temperature has a significant impact on the service performance of powder metallurgy titanium alloys. In this study, a high-temperature titanium alloy, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si, was prepared under different HIP temperatures (880–1000℃), and the microstructural evolution and mechanical properties were systematically investigated. The results demonstrated that the HIPed alloys were predominantly composed of more than 80 vol.% α phase and a small amount of β phase, and their phase compositions were basically unaffected by the HIP temperatures. Under the typical single-temperature-maintained HIP (STM-HIP) regime, the microstructure of alloy significantly coarsened as the HIP temperature increased, and the alloy strength exhibited an obvious linear negative correlation with the HIP temperature. On the basis of Hall–Petch relation, the prediction model of grain size was established, and the mathematical equation between HIP temperature and grain size (d=M(T_(HIP-N)^(-2))) was deduced. Furthermore, a possible evolution mechanism of microstructure was proposed, which could be divided into the decomposition of initial α′ martensite for as-received powder, formation of the globular α grains in prior particle boundaries (PPBs) region, and precipitation of the platelet α grains in non-PPBs region. For these alloys prepared by the dual-temperature-maintained HIP (DTM-HIP) regime, although their tensile properties were comparable to that of alloy prepared by STM-HIP regime with same high-temperature holding stage, higher proportion of globular α grains occurred due to more recrystallization nucleation during the low-temperature holding stage, which probably provided a solution for improving the dynamic service performance of HIPed alloys.
基金supported in part by the National Nature Science Foundation of China(92268206,81830064)the CAMS Innovation Fund for Medical Sciences(CIFMS,2019-I2M-5-059)+4 种基金the Military Medical Research Projects(145AKJ260015000X,2022-JCJQ-ZB-09600)the Military Key Basic Research of Foundational Strengthening Program(2020-JCJQ-ZD-256-021)the Science Foundation of National Defense Science and Technology for Excellent Young(2022-JCJQ-ZQ-017)the Military Medical Research and Development Projects(AWS17J005,2019-126)the Specific Research Fund of The Innovation Platform for Academicians of Hainan Province(YSPTZX202317).
文摘Scar formation resulting from burns or severe trauma can significantly compromise the structural integrity of skin and lead to permanent loss of skin appendages,ultimately impairing its normal physiological function.Accumulating evidence underscores the potential of targeted modulation of mechanical cues to enhance skin regeneration,promoting scarless repair by influencing the extracellular microenvironment and driving the phenotypic transitions.The field of skin repair and skin appendage regeneration has witnessed remarkable advancements in the utilization of biomaterials with distinct physical properties.However,a comprehensive understanding of the underlying mechanisms remains somewhat elusive,limiting the broader application of these innovations.In this review,we present two promising biomaterial-based mechanical approaches aimed at bolstering the regenerative capacity of compromised skin.The first approach involves leveraging biomaterials with specific biophysical properties to create an optimal scarless environment that supports cellular activities essential for regeneration.The second approach centers on harnessing mechanical forces exerted by biomaterials to enhance cellular plasticity,facilitating efficient cellular reprogramming and,consequently,promoting the regeneration of skin appendages.In summary,the manipulation of mechanical cues using biomaterial-based strategies holds significant promise as a supplementary approach for achieving scarless wound healing,coupled with the restoration of multiple skin appendage functions.
