Super-fine electrohydrodynamic inkjet(SIJ)printing of perovskite nanocrystal(PNC)colloid ink exhibits significant potential in the fabrication of high-resolution color conversion microstructures arrays for fullcolor m...Super-fine electrohydrodynamic inkjet(SIJ)printing of perovskite nanocrystal(PNC)colloid ink exhibits significant potential in the fabrication of high-resolution color conversion microstructures arrays for fullcolor micro-LED displays.However,the impact of solvent on both the printing process and the morphology of SIJ-printed PNC color conversion microstructures remains underexplored.In this study,we prepared samples of CsPbBr3PNC colloid inks in various solvents and investigated the solvent's impact on SIJ printed PNC microstructures.Our findings reveal that the boiling point of the solvent is crucial to the SIJ printing process of PNC colloid inks.Only does the boiling point of the solvent fall in the optimal range,the regular positioned,micron-scaled,conical PNC microstructures can be successfully printed.Below this optimal range,the ink is unable to be ejected from the nozzle;while above this range,irregular positioned microstructures with nanoscale height and coffee-ring-like morphology are produced.Based on these observations,high-resolution color conversion PNC microstructures were effectively prepared using SIJ printing of PNC colloid ink dispersed in dimethylbenzene solvent.展开更多
This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C s...This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C significantly improved the mechanical properties, including a notable 18.2% increase in hardness(HV 332). Fretting wear tests against 316L stainless steel(SS316L) balls demonstrated a 20wt%–22wt% reduction in wear volume in the Ti6Al4V/Ti C composites compared with the monolithic alloy. Microstructural analysis revealed that Ti C reinforcement controlled the grain orientation and reduced the β-phase content, which contributed to enhanced mechanical properties. The monolithic alloy exhibited a Widmanstätten lamellar microstructure, while increasing the Ti C content modified the wear mechanisms from ploughing and adhesion(0–0.5wt%) to pitting and abrasion(1wt%–2.5wt%). At higher reinforcement levels, the formation of a robust oxide layer through tribo-oxide treatment effectively reduced the wear volume by minimizing the abrasive effects and plastic deformation. This study highlights the potential of SPS-mediated Ti C reinforcement as a transformative approach for improving the performance of Ti6Al4V alloys, paving the way for advanced medical applications.展开更多
It is one of the big bottleneck problems for graphene to be uniformly distributed in ceramic matrix composites. A two-step approach was applied to prepare Graphene Nanoplatelets/Yt tria-Stabilized Zirconia(GNPs/YSZ) c...It is one of the big bottleneck problems for graphene to be uniformly distributed in ceramic matrix composites. A two-step approach was applied to prepare Graphene Nanoplatelets/Yt tria-Stabilized Zirconia(GNPs/YSZ) composites. Initially, GNPs were combined with YSZ through nanoparticle regranulation technology to obtain uniformly dispersed powders. Subsequently, the prepared powders were sintered by Spark Plasma Sintering(SPS). Systematic investigation was carried out to examine how GNPs regulate the phase, microstructures, and nanomechanical properties of GNPs/YSZ composite ceramics with different sintering temperatures.Results show that the GNPs can inhibit the coalescence of adjacent grains in YSZ ceramics. Herein,we propose that the intensity ratio of 2D peak to G peak of GNPs in Raman spectrum serves as a key indicator to assess the nanomechanical properties of GNPs/YSZ composites. When the intensity ratio of 2D peak to G peak is 0.5–0.6, the GNPs/YSZ composites obtained in the sintering temperature range of 1 200–1 250.C exhibit excellent nanomechanical properties such as hardness,elastic modulus, wear and creep resistance.展开更多
We have described in detail the effects of nano-SiO_(2),nano-CaCO_(3),carbon nanotubes,and nano-Al_(2)O_(3) on geopolymer concrete from the perspectives of macro mechanics and microstructure.The existing research resu...We have described in detail the effects of nano-SiO_(2),nano-CaCO_(3),carbon nanotubes,and nano-Al_(2)O_(3) on geopolymer concrete from the perspectives of macro mechanics and microstructure.The existing research results show that the mechanism of nano-materials on geopolymer concrete mainly includes the filling effect,nucleation effect,and bridging effect,the appropriate amount of nano-materials can be used as fillers to reduce the porosity of geopolymer concrete,and can also react with Ca(OH)2 to produce C-S-H gel,thereby improving the mechanical properties of geopolymer concrete.The optimum content of nano-SiO_(2) is between 1.0%and 2.0%.The optimum content of nano-CaCO_(3) is between 2.0%and 3.0%.The optimum content of carbon nanotubes is between 0.1%and 0.2%.The optimum content of nano-Al_(2)O_(3) is between 1.0%and 2.0%.The main problems existing in the research and application of nanomaterial-modified geopolymer concrete are summarized,which lays a foundation for the further application of nanomaterial in geopolymer concrete.展开更多
Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on common carbon steel surface by pulse electrodeposition of nickel, tungsten, phosphorus, rare earth （nano-CeO2） and silicon carbide （nano-SiO2） particles. T...Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on common carbon steel surface by pulse electrodeposition of nickel, tungsten, phosphorus, rare earth （nano-CeO2） and silicon carbide （nano-SiO2） particles. The effects of nano-CeO2 concentrations in electrolyte on microstructures and properties of nano-composite coatings were studied. The samples were characterized with chemical compositions, elements distributions, microhardness and microstructures. The results indicated that when nano-CeO2 concentration was controlled at 10 g/L, the nano-composite coatings possessed higher microhardness and compact microstmctures with clear outline of spherical matrix metal crystallites, fine crystallite sizes and uniform distribution of elements W, P, Ce and Si within the Ni-W-P matrix metal. Increasing the nano-CeO2 particles concentrations from 4 to 10 g/L led to refinement in grain structure and improvement of microstructures, while when increased to 14 g/L, the crystallite sizes began to increase again and there were a lot of small boss with nodulation shape appearing on the nano-composite coatings surface.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
The effect of different intermediate annealing heat treatments on the surface microstructures and anodic oxide film structures of rolled Al-5.6Mg sheets was studied.The results show that when the continuous annealing ...The effect of different intermediate annealing heat treatments on the surface microstructures and anodic oxide film structures of rolled Al-5.6Mg sheets was studied.The results show that when the continuous annealing is used to control microstructures of the sheets instead of the static state annealing in the intermediate annealing process,the surface grain size of the sheets can be reduced by about 65.7%,and the size of the Mg precipitation phase(Mg_(2)Al_(3))can be reduced by about 67%.Under the combined influence of grain size,precipitation phase,and texture,the highest glossiness can be obtained,which is attributed to continuous intermediate annealing and stabilization annealing at low temperature.The uniform grain and precipitation structures is beneficial to reducing the inhomogeneous dissolution of the oxide film and to obtain the anodic oxide film with uniform thickness and high glossiness.展开更多
Metal–organic frameworks(MOFs) are of great interest as potential electrochemically active materials.However, few studies have been conducted into understanding whether control of the shape and components of MOFs can...Metal–organic frameworks(MOFs) are of great interest as potential electrochemically active materials.However, few studies have been conducted into understanding whether control of the shape and components of MOFs can optimize their electrochemical performances due to the rational realization of their shapes. Component control of MOFs remains a significant challenge. Herein, we demonstrate a solvothermal method to realize nanostructure engineering of 2D nanoflake MOFs. The hollow structures withNi/Co-and Ni-MOF(denoted as Ni/Co-MOF nanoflakes and Ni-MOF nanoflakes) were assembled for their electrochemical performance optimizations in supercapacitors and in the oxygen reduction reaction(ORR). As a result, the Ni/CoMOF nanoflakes exhibited remarkably enhanced performance with a specific capacitance of 530.4 F g^(-1)at 0.5 A g^(-1)in1 M LiO H aqueous solution, much higher than that of NiMOF(306.8 F g^(-1)) and ZIF-67(168.3 F g^(-1)), a good rate capability, and a robust cycling performance with no capacity fading after 2000 cycles. Ni/Co-MOF nanoflakes also showed improved electrocatalytic performance for the ORR compared to Ni-MOF and ZIF-67. The present work highlights the significant role of tuning 2D nanoflake ensembles of Ni/Co-MOF in accelerating electron and charge transportation for optimizing energy storage and conversion devices.展开更多
A bulk nanostructured Al-10.0Zn-2.8Mg-1.8Cu alloy was synthesized by cryomilling first and then by spark plasma sintering （SPS）, and the effect of heat treatment on the microstructures and mechanical properties of t...A bulk nanostructured Al-10.0Zn-2.8Mg-1.8Cu alloy was synthesized by cryomilling first and then by spark plasma sintering （SPS）, and the effect of heat treatment on the microstructures and mechanical properties of this alloy were studied. Most MgZn2 particles with a coarse size lie on the grain boundaries of the SPS-processed sample. After solid solution and artificial aging, fine spherical-like MgZn2 particles precipitate uniformly in the grain interiors. No obvious grain growth is found after the heat treatment. A nanoindentation study indicates that no clear change is found in the Yong＇s modulus of the nanostructured alloy after the heat treatment. However, the hardness of the nanostructured alloy increases by about 33% after the heat treatment, which is attributed to the effect of precipitation-hardening.展开更多
Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on the carbon steel surface by pulse co-deposition of nickel, tungsten, phosphorus, nano-CeO2 and nano-SiO2 particles. The influence of nano-SiO2 particles concen...Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on the carbon steel surface by pulse co-deposition of nickel, tungsten, phosphorus, nano-CeO2 and nano-SiO2 particles. The influence of nano-SiO2 particles concentrations in electrolyte on microstructures and properties of the nano-composite coatings were researched, and the characteristics were assessed by chemical compositions, element distribution, deposition rate, microhardness and microstructures. The results indicate that when nano-SiO2 particles concentrations in electrolyte are controlled at 20 g·L-1, the deposition rate with 27.07 μm·h-1 and the microhardness with 666 Hv of the nano-composite coatings are highest, element line scanning and area scanning analyses show that the average contents of elements W, P, Si and Ce in the nano-composite coatings are close, displaying that the distribution of every element within the nano-composite coatings is even. An increase in nano-SiO2 particles concentrations in electrolyte (when lower than 20 g·L-1) leads to refinement in grain structure of nano-composite coatings, but when it improved to 30 g·L-1, the crystallite sizes increase again and in the meantime there are a lot of small boss with nodulation shape appearing on the surface of nano-composite coatings.展开更多
The microstructures and crack propagating characteristic of Si 3N 4 (μ)/SiC (n, w) composite ceramic were studied with AEM. The Si 3N 4 (μ)/SiC (n, w) composite ceramic consists of β Si 3N 4, β SiC, a smal...The microstructures and crack propagating characteristic of Si 3N 4 (μ)/SiC (n, w) composite ceramic were studied with AEM. The Si 3N 4 (μ)/SiC (n, w) composite ceramic consists of β Si 3N 4, β SiC, a small amount of α Si 3N 4 and α SiC, and amorphous phase. Most of Si 3N 4 grains were equiaxed crystal and also there were some bulky columnar ones. Most of SiC particles and SiC whiskers distributed at the Si 3N 4 grain boundaries and a few of smaller SiC particles in the Si 3N 4 grains. Most of amorphous structure was in the junction of several Si 3N 4 grains and thin amorphous layer was observed only at a few of Si 3N 4 boundaries. Failured cracks propagated mainly along the boundaries of the Si 3N 4 grains and partially passed through Si 3N 4 grains. The path of crack propagating might change, branching and twisting of the cracks might occur when the expanding crack meet the SiC particle and/or SiC whisker. Effect of the microstructure on strength and toughness of the composite ceramic was briefly discussed.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
High entropy alloys(HEAs)have recently received extensive attention due to their appealing mechani-cal performance given their simple phase formation.This study utilized laser powder bed fusion(LPBF)to fabricate high-...High entropy alloys(HEAs)have recently received extensive attention due to their appealing mechani-cal performance given their simple phase formation.This study utilized laser powder bed fusion(LPBF)to fabricate high-performance HEA components.By processing respective powder blends,LPBF enabled the fabrication of stronger composites with a uniformly distributed reinforcing phase.Here,the impact of varying content of nano-scale TiC(1-3 wt%)particles for strengthening the CoCrFeMnNi HEA was ex-plored.The microstructural features and mechanical properties of the HEA composites were investigated in detail.The introduction of nano-scale TiC into the HEA matrix encouraged the development of cross-scale hierarchical microstructure and eliminated the formation of oxide inclusions.Incorporating more nano-TiC led to a higher dislocation density and more refined microstructure in the HEA composites,whereas it posed little influence on the anisotropy of the HEA matrix which typically featured a<001>texture along the building direction.With an optimized content of nano-TiC(1-2 wt%),the strength-ductility trade-offcan be overcome by exploiting multiple strengthening mechanisms encompassing grain boundary strengthening,solid solution strengthening,Orowan strengthening,and dislocation strengthen-ing.The HEA composites showed a favored strength-ductility combination with a yield strength of 748-882 MPa,ultimate tensile strength of 931-1081 MPa,and fracture elongation of 23%-29%.This study demonstrates that the introduction of nano-scale TiC is an effective way to simultaneously improve the strength and ductility of additively manufactured HEA materials.展开更多
Ni-W-P base composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by pulse co-deposition of Ni,W,P,CeO2 and SiO2 nano-particles.The influence of SiO2 concentrations in bath on...Ni-W-P base composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by pulse co-deposition of Ni,W,P,CeO2 and SiO2 nano-particles.The influence of SiO2 concentrations in bath on microstructures and properties of Ni-W-P/CeO2-SiO2 composites was studied,and the characteristics were assessed by chemical compositions,element distribution,surface morphologies,deposition rate and microhardness.The results indicate that when SiO2 concentration in bath is controlled at 20 g/L,the composites possess the fastest deposition rate,the highest microhardness,compact microstructures,smaller crystallite sizes and uniform distribution of W,P,Ce and Si within Ni-W-P matrix metal.Increasing SiO2 concentration in bath from 10 to 20 g/L leads to the refinement in grain size and the inhomogeneity of microstructures.While when SiO2 concentration is increased to 30 g/L,the crystallite sizes increase again and some bosses with nodulation shape appear on the surface of composites.展开更多
Ferroelastic rare earth tantalates(RETaO_(4))are widely researched as the next-generation thermal barrier coatings(TBCs),and RETaO_(4)powders are hugely significant for synthesizing their coatings.The current research...Ferroelastic rare earth tantalates(RETaO_(4))are widely researched as the next-generation thermal barrier coatings(TBCs),and RETaO_(4)powders are hugely significant for synthesizing their coatings.The current research used chemical co-precipitation within an automated experimental device to synthesize RETaO_(4)(RE=Nd,Sm,Gd,Ho,Er)powders.The device automatically monitored and controlled the solutions'pH,improving the chemical co-precipitation efficiency.The crystal structure and microstructure of the RETaO_(4)powders can be controlled by changing the annealing temperature,and the materials undergo an m'-m phase transition.The m'-RETaO_(4)powders exhibit nano-size grains,while m-RETaO_(4)powders evince micron-size grains,altered by the annealing temperatures.A simultaneous thermal analysis es-timates the reversive ferroelastic tetragonal-monoclinic phase transition temperatures.Overall,this research focuses on the synthesis,crystal structures,microstructures,and phase transition of the fabricated RETaO_(4)powders.展开更多
The hot compression curves and deformed microstructures were investigated under various hot deformation conditions in three states:hot isostatic pressing(HIP,A1),HIP+hot extrusion at 1100℃(A2),and HIP+hot extrusion a...The hot compression curves and deformed microstructures were investigated under various hot deformation conditions in three states:hot isostatic pressing(HIP,A1),HIP+hot extrusion at 1100℃(A2),and HIP+hot extrusion at 1150℃(A3).The results show that A2 sample,extruded at 1100℃ with uniform γ+γ′duplex microstructures,demonstrates excellent hot deformation behavior at both 1050 and 1100℃.The true stress-true strain curves of A2 sample maintain a hardening-softening equilibrium over a larger strain range,with post-deformation average grain size of 5μm.The as-HIPed A1 sample and 1150℃ extruded A3 sample exhibit a softening region in deformation curves at 1050℃,and the grain microstructures reflect an incomplete recrystallized state,i.e.combination of fine recrystallized grains and initial larger grains,characterized by a necklace-like microstructure.The predominant recrystallization mechanism for these samples is strain-induced boundary migration.At 1150℃ with a strain rate of 0.001 s^(-1),the influence of the initial microstructure on hot deformation behavior and resultant microstructure is relatively less pronounced,and postdeformation microstructures are fully recrystallized grains.Fine-grained microstructures are conducive to maximizing the hot deformation potential of alloy.By judiciously adjusting deformation regimes,a fine and uniform deformed microstructure can be obtained.展开更多
Microscale metallic structures enhanced by additive manufacturing technology have attracted extensive attention especially in microelectronics and electromechanical devices.Meniscus-confined electrodeposition(MCED)adv...Microscale metallic structures enhanced by additive manufacturing technology have attracted extensive attention especially in microelectronics and electromechanical devices.Meniscus-confined electrodeposition(MCED)advances microscale 3D metal printing,enabling simpler fabrication of superior metallic microstructures in air without complex equipment or post-processing.However,accurately predicting growth rates with current MCED techniques remain challenging,which is essential for precise structure fabrication and preventing nozzle clogging.In this work,we present a novel approach to electrochemical 3D printing that utilizes a self-adjusting,voxelated method for fabricating metallic microstructures.Diverging from conventional voxelated printing which focuses on monitoring voxel thickness for structure control,this technique adopts a holistic strategy.It ensures each voxel’s position is in alignment with the final structure by synchronizing the micropipette’s trajectory during deposition with the intended design,thus facilitating self-regulation of voxel position and reducing errors associated with environmental fluctuations in deposition parameters.The method’s ability to print micropillars with various tilt angles,high density,and helical arrays demonstrates its refined control over the deposition process.Transmission electron microscopy analysis reveals that the deposited structures,which are fabricated through layer-by-layer(voxel)printing,contain nanotwins that are widely known to enhance the material’s mechanical and electrical properties.Correspondingly,in situ scanning electron microscopy(SEM)microcompression tests confirm this enhancement,showing these structures exhibit a compressive yield strength exceeding 1 GPa.The indentation tests provided an average hardness of 3.71 GPa,which is the highest value reported in previous work using MCED.The resistivity measured by the four-point probe method was(1.95±0.01)×10^(−7)Ω·m,nearly 11 times that of bulk copper.These findings demonstrate the considerable advantage of this technique in fabricating complex metallic microstructures with enhanced mechanical properties,making it suitable for advanced applications in microsensors,microelectronics,and micro-electromechanical systems.展开更多
Microstructures of nanoporous Pd are essentially important for its physical and chemical properties.In this work,we show that the microstructures of nanoporous Pd can be tuned by adjusting compositions of the precurso...Microstructures of nanoporous Pd are essentially important for its physical and chemical properties.In this work,we show that the microstructures of nanoporous Pd can be tuned by adjusting compositions of the precursor alloys,and dealloying and heat treatment parameters.Both the ligament and pore sizes decrease with increasing the electrochemical potential upon dealloying and the concentration of noble component in the precursor alloys.Heat treatment causes coarsening of the nanoporous structure.Above a critical temperature,the nanoporous structures are subjected to significant coarsening.Below the critical temperature,surface diffusion is believed to dominate the coarsening process.Above the critical temperature,the nanoporous structure coarsens remarkably at a rather high rate,which is ascribed to a multiple-mechanism controlled process.展开更多
93W-4.9Ni-2.1Fe alloys strengthened by nanoscale ZrC particles were prepared by spark-plasma-sintering(SPS)and hot rotary swaging,separately.Results show that the addition of a small number of ZrC nanoparticles can re...93W-4.9Ni-2.1Fe alloys strengthened by nanoscale ZrC particles were prepared by spark-plasma-sintering(SPS)and hot rotary swaging,separately.Results show that the addition of a small number of ZrC nanoparticles can refine grains and increase the hardness of the WNiFe alloys,but hinder the formation of theγ-(Ni,Fe)phase during SPS.SPSed WNiFe and WNiFe-ZrC alloys are brittle at room temperature,while the swaged WNiFe and WNiFe-0.5ZrC(wt%)alloys are ductile.At 400°C,the swaged WNiFe-0.5ZrC alloy exhibits both higher tensile strength and better ductility than the swaged WNiFe.The nanoscale particles distributed in the W grains andγ-(Ni,Fe)phase provide a good pinning effect,which enhances the strength.The thermal conductivity of swaged WNiFe-0.5ZrC is only 71 W·m^(-1)·K^(-1)at room temperature,but it increases to about 100 W·m^(-1)·K^(-1)at 800°C,which is close to that of pure W(121 W·m^(-1)·K^(-1)).These results show the potential of WNiFe alloys as plasma-facing materials in fusion reactor.展开更多
基金supported by the National Natural Science Foundation of China(No.62374142)Fundamental Research Funds for the Central Universities(Nos.20720220085 and 20720240064)+2 种基金External Cooperation Program of Fujian(No.2022I0004)Major Science and Technology Project of Xiamen in China(No.3502Z20191015)Xiamen Natural Science Foundation Youth Project(No.3502Z202471002)。
文摘Super-fine electrohydrodynamic inkjet(SIJ)printing of perovskite nanocrystal(PNC)colloid ink exhibits significant potential in the fabrication of high-resolution color conversion microstructures arrays for fullcolor micro-LED displays.However,the impact of solvent on both the printing process and the morphology of SIJ-printed PNC color conversion microstructures remains underexplored.In this study,we prepared samples of CsPbBr3PNC colloid inks in various solvents and investigated the solvent's impact on SIJ printed PNC microstructures.Our findings reveal that the boiling point of the solvent is crucial to the SIJ printing process of PNC colloid inks.Only does the boiling point of the solvent fall in the optimal range,the regular positioned,micron-scaled,conical PNC microstructures can be successfully printed.Below this optimal range,the ink is unable to be ejected from the nozzle;while above this range,irregular positioned microstructures with nanoscale height and coffee-ring-like morphology are produced.Based on these observations,high-resolution color conversion PNC microstructures were effectively prepared using SIJ printing of PNC colloid ink dispersed in dimethylbenzene solvent.
文摘This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C significantly improved the mechanical properties, including a notable 18.2% increase in hardness(HV 332). Fretting wear tests against 316L stainless steel(SS316L) balls demonstrated a 20wt%–22wt% reduction in wear volume in the Ti6Al4V/Ti C composites compared with the monolithic alloy. Microstructural analysis revealed that Ti C reinforcement controlled the grain orientation and reduced the β-phase content, which contributed to enhanced mechanical properties. The monolithic alloy exhibited a Widmanstätten lamellar microstructure, while increasing the Ti C content modified the wear mechanisms from ploughing and adhesion(0–0.5wt%) to pitting and abrasion(1wt%–2.5wt%). At higher reinforcement levels, the formation of a robust oxide layer through tribo-oxide treatment effectively reduced the wear volume by minimizing the abrasive effects and plastic deformation. This study highlights the potential of SPS-mediated Ti C reinforcement as a transformative approach for improving the performance of Ti6Al4V alloys, paving the way for advanced medical applications.
基金supported from the National Natural Science Foundation of China(No.52371062)the Open Foundation from National Key Laboratory of Materials Behavior and Evaluation Technology in Space Environments,China,the National Key Research and Development Program of China(No.2020YFB2007900)the National Major Science and Technology Projects of China(No.2017-VI-0020-0093).
文摘It is one of the big bottleneck problems for graphene to be uniformly distributed in ceramic matrix composites. A two-step approach was applied to prepare Graphene Nanoplatelets/Yt tria-Stabilized Zirconia(GNPs/YSZ) composites. Initially, GNPs were combined with YSZ through nanoparticle regranulation technology to obtain uniformly dispersed powders. Subsequently, the prepared powders were sintered by Spark Plasma Sintering(SPS). Systematic investigation was carried out to examine how GNPs regulate the phase, microstructures, and nanomechanical properties of GNPs/YSZ composite ceramics with different sintering temperatures.Results show that the GNPs can inhibit the coalescence of adjacent grains in YSZ ceramics. Herein,we propose that the intensity ratio of 2D peak to G peak of GNPs in Raman spectrum serves as a key indicator to assess the nanomechanical properties of GNPs/YSZ composites. When the intensity ratio of 2D peak to G peak is 0.5–0.6, the GNPs/YSZ composites obtained in the sintering temperature range of 1 200–1 250.C exhibit excellent nanomechanical properties such as hardness,elastic modulus, wear and creep resistance.
基金Funded by the National Natural Science Foundation of China(Nos.U23A20672,52171270,51879168)the PI Project of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML20240001,GML2024009)。
文摘We have described in detail the effects of nano-SiO_(2),nano-CaCO_(3),carbon nanotubes,and nano-Al_(2)O_(3) on geopolymer concrete from the perspectives of macro mechanics and microstructure.The existing research results show that the mechanism of nano-materials on geopolymer concrete mainly includes the filling effect,nucleation effect,and bridging effect,the appropriate amount of nano-materials can be used as fillers to reduce the porosity of geopolymer concrete,and can also react with Ca(OH)2 to produce C-S-H gel,thereby improving the mechanical properties of geopolymer concrete.The optimum content of nano-SiO_(2) is between 1.0%and 2.0%.The optimum content of nano-CaCO_(3) is between 2.0%and 3.0%.The optimum content of carbon nanotubes is between 0.1%and 0.2%.The optimum content of nano-Al_(2)O_(3) is between 1.0%and 2.0%.The main problems existing in the research and application of nanomaterial-modified geopolymer concrete are summarized,which lays a foundation for the further application of nanomaterial in geopolymer concrete.
基金Applied Basic Research Plans Program of Yunnan Province(2007E187M)Scientific Research Fund (2006-02)Analysis and Measurement Research Fund (2007-22) of Kunming University of Science and Technology
文摘Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on common carbon steel surface by pulse electrodeposition of nickel, tungsten, phosphorus, rare earth （nano-CeO2） and silicon carbide （nano-SiO2） particles. The effects of nano-CeO2 concentrations in electrolyte on microstructures and properties of nano-composite coatings were studied. The samples were characterized with chemical compositions, elements distributions, microhardness and microstructures. The results indicated that when nano-CeO2 concentration was controlled at 10 g/L, the nano-composite coatings possessed higher microhardness and compact microstmctures with clear outline of spherical matrix metal crystallites, fine crystallite sizes and uniform distribution of elements W, P, Ce and Si within the Ni-W-P matrix metal. Increasing the nano-CeO2 particles concentrations from 4 to 10 g/L led to refinement in grain structure and improvement of microstructures, while when increased to 14 g/L, the crystallite sizes began to increase again and there were a lot of small boss with nodulation shape appearing on the nano-composite coatings surface.
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.
文摘The effect of different intermediate annealing heat treatments on the surface microstructures and anodic oxide film structures of rolled Al-5.6Mg sheets was studied.The results show that when the continuous annealing is used to control microstructures of the sheets instead of the static state annealing in the intermediate annealing process,the surface grain size of the sheets can be reduced by about 65.7%,and the size of the Mg precipitation phase(Mg_(2)Al_(3))can be reduced by about 67%.Under the combined influence of grain size,precipitation phase,and texture,the highest glossiness can be obtained,which is attributed to continuous intermediate annealing and stabilization annealing at low temperature.The uniform grain and precipitation structures is beneficial to reducing the inhomogeneous dissolution of the oxide film and to obtain the anodic oxide film with uniform thickness and high glossiness.
基金supported by the National Natural Science Foundation of China (Nos. 21571157, U1604123, and 51473149)Outstanding Young Talent Research Fund of Zhengzhou University (1521320001)+1 种基金the Open Project Foundation of Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) (2017–29),Nankai UniversityOpen Project Foundation of Key Laboratory of Inorganic Synthesis and Preparation of Jilin University
文摘Metal–organic frameworks(MOFs) are of great interest as potential electrochemically active materials.However, few studies have been conducted into understanding whether control of the shape and components of MOFs can optimize their electrochemical performances due to the rational realization of their shapes. Component control of MOFs remains a significant challenge. Herein, we demonstrate a solvothermal method to realize nanostructure engineering of 2D nanoflake MOFs. The hollow structures withNi/Co-and Ni-MOF(denoted as Ni/Co-MOF nanoflakes and Ni-MOF nanoflakes) were assembled for their electrochemical performance optimizations in supercapacitors and in the oxygen reduction reaction(ORR). As a result, the Ni/CoMOF nanoflakes exhibited remarkably enhanced performance with a specific capacitance of 530.4 F g^(-1)at 0.5 A g^(-1)in1 M LiO H aqueous solution, much higher than that of NiMOF(306.8 F g^(-1)) and ZIF-67(168.3 F g^(-1)), a good rate capability, and a robust cycling performance with no capacity fading after 2000 cycles. Ni/Co-MOF nanoflakes also showed improved electrocatalytic performance for the ORR compared to Ni-MOF and ZIF-67. The present work highlights the significant role of tuning 2D nanoflake ensembles of Ni/Co-MOF in accelerating electron and charge transportation for optimizing energy storage and conversion devices.
基金supported by the National High-Tech Research and Development Program of China (No.2002AA302502)
文摘A bulk nanostructured Al-10.0Zn-2.8Mg-1.8Cu alloy was synthesized by cryomilling first and then by spark plasma sintering （SPS）, and the effect of heat treatment on the microstructures and mechanical properties of this alloy were studied. Most MgZn2 particles with a coarse size lie on the grain boundaries of the SPS-processed sample. After solid solution and artificial aging, fine spherical-like MgZn2 particles precipitate uniformly in the grain interiors. No obvious grain growth is found after the heat treatment. A nanoindentation study indicates that no clear change is found in the Yong＇s modulus of the nanostructured alloy after the heat treatment. However, the hardness of the nanostructured alloy increases by about 33% after the heat treatment, which is attributed to the effect of precipitation-hardening.
基金Projects supported by Applied Basic Research Plans Programof Yunnan Province (2007E 187M)Scientific Research Fund(2006-02)Analysis and Measurement Research Fund (2007-22) of Kunming University of Science and Technology
文摘Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on the carbon steel surface by pulse co-deposition of nickel, tungsten, phosphorus, nano-CeO2 and nano-SiO2 particles. The influence of nano-SiO2 particles concentrations in electrolyte on microstructures and properties of the nano-composite coatings were researched, and the characteristics were assessed by chemical compositions, element distribution, deposition rate, microhardness and microstructures. The results indicate that when nano-SiO2 particles concentrations in electrolyte are controlled at 20 g·L-1, the deposition rate with 27.07 μm·h-1 and the microhardness with 666 Hv of the nano-composite coatings are highest, element line scanning and area scanning analyses show that the average contents of elements W, P, Si and Ce in the nano-composite coatings are close, displaying that the distribution of every element within the nano-composite coatings is even. An increase in nano-SiO2 particles concentrations in electrolyte (when lower than 20 g·L-1) leads to refinement in grain structure of nano-composite coatings, but when it improved to 30 g·L-1, the crystallite sizes increase again and in the meantime there are a lot of small boss with nodulation shape appearing on the surface of nano-composite coatings.
文摘The microstructures and crack propagating characteristic of Si 3N 4 (μ)/SiC (n, w) composite ceramic were studied with AEM. The Si 3N 4 (μ)/SiC (n, w) composite ceramic consists of β Si 3N 4, β SiC, a small amount of α Si 3N 4 and α SiC, and amorphous phase. Most of Si 3N 4 grains were equiaxed crystal and also there were some bulky columnar ones. Most of SiC particles and SiC whiskers distributed at the Si 3N 4 grain boundaries and a few of smaller SiC particles in the Si 3N 4 grains. Most of amorphous structure was in the junction of several Si 3N 4 grains and thin amorphous layer was observed only at a few of Si 3N 4 boundaries. Failured cracks propagated mainly along the boundaries of the Si 3N 4 grains and partially passed through Si 3N 4 grains. The path of crack propagating might change, branching and twisting of the cracks might occur when the expanding crack meet the SiC particle and/or SiC whisker. Effect of the microstructure on strength and toughness of the composite ceramic was briefly discussed.
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This work was financially supported by the National Natural Science Foundation of China(Nos.11972202,51905279).
文摘High entropy alloys(HEAs)have recently received extensive attention due to their appealing mechani-cal performance given their simple phase formation.This study utilized laser powder bed fusion(LPBF)to fabricate high-performance HEA components.By processing respective powder blends,LPBF enabled the fabrication of stronger composites with a uniformly distributed reinforcing phase.Here,the impact of varying content of nano-scale TiC(1-3 wt%)particles for strengthening the CoCrFeMnNi HEA was ex-plored.The microstructural features and mechanical properties of the HEA composites were investigated in detail.The introduction of nano-scale TiC into the HEA matrix encouraged the development of cross-scale hierarchical microstructure and eliminated the formation of oxide inclusions.Incorporating more nano-TiC led to a higher dislocation density and more refined microstructure in the HEA composites,whereas it posed little influence on the anisotropy of the HEA matrix which typically featured a<001>texture along the building direction.With an optimized content of nano-TiC(1-2 wt%),the strength-ductility trade-offcan be overcome by exploiting multiple strengthening mechanisms encompassing grain boundary strengthening,solid solution strengthening,Orowan strengthening,and dislocation strengthen-ing.The HEA composites showed a favored strength-ductility combination with a yield strength of 748-882 MPa,ultimate tensile strength of 931-1081 MPa,and fracture elongation of 23%-29%.This study demonstrates that the introduction of nano-scale TiC is an effective way to simultaneously improve the strength and ductility of additively manufactured HEA materials.
基金Project(20806035) supported by the National Natural Science Foundation of ChinaProject(2009CI026) supported by Back-up Personnel Foundation of Academic and Technology Leaders of Yunnan Province,China+4 种基金Project(KKZ6200927001) supported by Opening Fund of Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences Project(2007E187M) supported by Applied Basic Research Plans of Yunnan Province,ChinaProject(08C0025) supported by Scientific Research Fund of Yunnan Provincial Education Department, China Project(KKZ3200927029) supported by Training Foundation for Talents of Kunming University of Science and Technology,ChinaProject(2008-003) supported by Analysis and Measurement Research Fund of Kunming University of Science and Technology,China
文摘Ni-W-P base composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by pulse co-deposition of Ni,W,P,CeO2 and SiO2 nano-particles.The influence of SiO2 concentrations in bath on microstructures and properties of Ni-W-P/CeO2-SiO2 composites was studied,and the characteristics were assessed by chemical compositions,element distribution,surface morphologies,deposition rate and microhardness.The results indicate that when SiO2 concentration in bath is controlled at 20 g/L,the composites possess the fastest deposition rate,the highest microhardness,compact microstructures,smaller crystallite sizes and uniform distribution of W,P,Ce and Si within Ni-W-P matrix metal.Increasing SiO2 concentration in bath from 10 to 20 g/L leads to the refinement in grain size and the inhomogeneity of microstructures.While when SiO2 concentration is increased to 30 g/L,the crystallite sizes increase again and some bosses with nodulation shape appear on the surface of composites.
基金the Rare and Precious Metals Material Genetic Engineering Project of Yunnan Province(202102AB080019-1)National Key Research and Development Program of China(2022YFB3708600)the National Natural Science Foundation of China(91960103).
文摘Ferroelastic rare earth tantalates(RETaO_(4))are widely researched as the next-generation thermal barrier coatings(TBCs),and RETaO_(4)powders are hugely significant for synthesizing their coatings.The current research used chemical co-precipitation within an automated experimental device to synthesize RETaO_(4)(RE=Nd,Sm,Gd,Ho,Er)powders.The device automatically monitored and controlled the solutions'pH,improving the chemical co-precipitation efficiency.The crystal structure and microstructure of the RETaO_(4)powders can be controlled by changing the annealing temperature,and the materials undergo an m'-m phase transition.The m'-RETaO_(4)powders exhibit nano-size grains,while m-RETaO_(4)powders evince micron-size grains,altered by the annealing temperatures.A simultaneous thermal analysis es-timates the reversive ferroelastic tetragonal-monoclinic phase transition temperatures.Overall,this research focuses on the synthesis,crystal structures,microstructures,and phase transition of the fabricated RETaO_(4)powders.
基金Shenzhen Science and Technology Program(KJZD20230923113900001)Project of Industry and Information Technology Bureau of Shenzhen Municipality(201806071403422960)。
文摘The hot compression curves and deformed microstructures were investigated under various hot deformation conditions in three states:hot isostatic pressing(HIP,A1),HIP+hot extrusion at 1100℃(A2),and HIP+hot extrusion at 1150℃(A3).The results show that A2 sample,extruded at 1100℃ with uniform γ+γ′duplex microstructures,demonstrates excellent hot deformation behavior at both 1050 and 1100℃.The true stress-true strain curves of A2 sample maintain a hardening-softening equilibrium over a larger strain range,with post-deformation average grain size of 5μm.The as-HIPed A1 sample and 1150℃ extruded A3 sample exhibit a softening region in deformation curves at 1050℃,and the grain microstructures reflect an incomplete recrystallized state,i.e.combination of fine recrystallized grains and initial larger grains,characterized by a necklace-like microstructure.The predominant recrystallization mechanism for these samples is strain-induced boundary migration.At 1150℃ with a strain rate of 0.001 s^(-1),the influence of the initial microstructure on hot deformation behavior and resultant microstructure is relatively less pronounced,and postdeformation microstructures are fully recrystallized grains.Fine-grained microstructures are conducive to maximizing the hot deformation potential of alloy.By judiciously adjusting deformation regimes,a fine and uniform deformed microstructure can be obtained.
基金supported in part by National Key R&D Program of China under Grant 2023YFB4705600in part by the National Natural Science Foundation of China under Grants 61925304,62127810 and 62203138+1 种基金in part by the National Postdoctoral Program for Innovative Talents under Grant BX20200107in part by the Self-Planned Task(No.SKLRS202205C)of State Key Laboratory of Robotics and System(HIT).
文摘Microscale metallic structures enhanced by additive manufacturing technology have attracted extensive attention especially in microelectronics and electromechanical devices.Meniscus-confined electrodeposition(MCED)advances microscale 3D metal printing,enabling simpler fabrication of superior metallic microstructures in air without complex equipment or post-processing.However,accurately predicting growth rates with current MCED techniques remain challenging,which is essential for precise structure fabrication and preventing nozzle clogging.In this work,we present a novel approach to electrochemical 3D printing that utilizes a self-adjusting,voxelated method for fabricating metallic microstructures.Diverging from conventional voxelated printing which focuses on monitoring voxel thickness for structure control,this technique adopts a holistic strategy.It ensures each voxel’s position is in alignment with the final structure by synchronizing the micropipette’s trajectory during deposition with the intended design,thus facilitating self-regulation of voxel position and reducing errors associated with environmental fluctuations in deposition parameters.The method’s ability to print micropillars with various tilt angles,high density,and helical arrays demonstrates its refined control over the deposition process.Transmission electron microscopy analysis reveals that the deposited structures,which are fabricated through layer-by-layer(voxel)printing,contain nanotwins that are widely known to enhance the material’s mechanical and electrical properties.Correspondingly,in situ scanning electron microscopy(SEM)microcompression tests confirm this enhancement,showing these structures exhibit a compressive yield strength exceeding 1 GPa.The indentation tests provided an average hardness of 3.71 GPa,which is the highest value reported in previous work using MCED.The resistivity measured by the four-point probe method was(1.95±0.01)×10^(−7)Ω·m,nearly 11 times that of bulk copper.These findings demonstrate the considerable advantage of this technique in fabricating complex metallic microstructures with enhanced mechanical properties,making it suitable for advanced applications in microsensors,microelectronics,and micro-electromechanical systems.
基金supported financially by the National Natural Science Foundation of China(Nos.51771153,51371147,51790481 and 51431008)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(No.CX201825)。
文摘Microstructures of nanoporous Pd are essentially important for its physical and chemical properties.In this work,we show that the microstructures of nanoporous Pd can be tuned by adjusting compositions of the precursor alloys,and dealloying and heat treatment parameters.Both the ligament and pore sizes decrease with increasing the electrochemical potential upon dealloying and the concentration of noble component in the precursor alloys.Heat treatment causes coarsening of the nanoporous structure.Above a critical temperature,the nanoporous structures are subjected to significant coarsening.Below the critical temperature,surface diffusion is believed to dominate the coarsening process.Above the critical temperature,the nanoporous structure coarsens remarkably at a rather high rate,which is ascribed to a multiple-mechanism controlled process.
基金National Key Research and Development Program of China(2022YFE03140002,2019YFE03110200)National Natural Science Foundation of China(52273320,52173303,52325103,52171084)+2 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0470000)Anhui Provincial Natural Science Foundation(2308085J07)HFIPS Director's Fund(YZJJ202102,YZJJQY202306,YZJJKX202202)。
文摘93W-4.9Ni-2.1Fe alloys strengthened by nanoscale ZrC particles were prepared by spark-plasma-sintering(SPS)and hot rotary swaging,separately.Results show that the addition of a small number of ZrC nanoparticles can refine grains and increase the hardness of the WNiFe alloys,but hinder the formation of theγ-(Ni,Fe)phase during SPS.SPSed WNiFe and WNiFe-ZrC alloys are brittle at room temperature,while the swaged WNiFe and WNiFe-0.5ZrC(wt%)alloys are ductile.At 400°C,the swaged WNiFe-0.5ZrC alloy exhibits both higher tensile strength and better ductility than the swaged WNiFe.The nanoscale particles distributed in the W grains andγ-(Ni,Fe)phase provide a good pinning effect,which enhances the strength.The thermal conductivity of swaged WNiFe-0.5ZrC is only 71 W·m^(-1)·K^(-1)at room temperature,but it increases to about 100 W·m^(-1)·K^(-1)at 800°C,which is close to that of pure W(121 W·m^(-1)·K^(-1)).These results show the potential of WNiFe alloys as plasma-facing materials in fusion reactor.
