Silicon carbide fibers are considered ideal reinforcing materials for ceramic matrix composites due to their excellent mechanical properties and high-temperature performance.Different types of fibers necessitate indiv...Silicon carbide fibers are considered ideal reinforcing materials for ceramic matrix composites due to their excellent mechanical properties and high-temperature performance.Different types of fibers necessitate individual investigation due to variations in their composition and fabrication processes.This study presents a comprehensive investigation into evolution of the mechanical properties,surface microstructure,and composition of Shicolon-Ⅱ fibers subjected to argon heat treatment at temperatures ranging from 1300℃to 1700℃.The Shicolon-Ⅱ fibers are composed of small-sized β-SiC grains,SiC_(x)O_(y) amorphous phase,and a minor amount of graphite microcrystals.Following treatment in an argon atmosphere at 1300℃,the fibers maintain a monofilament tensile strength of 3.620 GPa,corresponding to a retention of 98.32%.This strength diminishes to 2.875 GPa,equating to a retention of 78.08%,after treatment at 1500℃.The reduction in mechanical properties of the fibers can be ascribed to the decomposition of the amorphous phase and the growth of β-SiC grains.Furthermore,creep resistance is an essential factor influencing the long-term performance of composite materials.After treatment at temperatures above 1400℃,the high-temperature creep resistance of the fibers is significantly enhanced due to growth of β-SiC grains.This study offers valuable theoretical insights into high-temperature applications of second-generation fibers,contributing to an enhanced understanding of their performance under extreme conditions.展开更多
The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solutio...The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solution were used to regulate the microstructure,mechanical properties,and corrosion properties of B_(4)C/TC4 composite.Results show that with the increase in temperature from 500℃to 800°C,partial lamellarα-Ti in the as-deposited sample is gradually transformed into equiaxedα-Ti,accompanied by the disappearance of basketweave microstructure.At 1100°C,a small portion of TiC phase suffers fusion.This composite exhibits the optimal combination of strength and plasticity after annealing at 500℃for 4 h followed by furnace cooling,which is attributed to the stress release effect and the refined basketweave microstructure.However,this composite shows a decline in corrosion resistance after various heat treatments due to grain coarsening and micro-galvanic corrosion.展开更多
Cryogenic rolling impacts on microstructure and mechanical properties of spray-formed 7055(SF-7055)Al alloy were investigated.Results show that with the increase of the reduction from 20%to 80%,the grain of cryogenic ...Cryogenic rolling impacts on microstructure and mechanical properties of spray-formed 7055(SF-7055)Al alloy were investigated.Results show that with the increase of the reduction from 20%to 80%,the grain of cryogenic rolled SF-7055 Al alloy is elongated to form a fiber texture.Numerous proliferating dislocations in the microstructure accumulate into dislocation walls and cells,and eventually form subgrains.These subgrain boundaries divide the original grain,thereby reducing the grain size.Under severe deformation conditions,they even enable the formation of nanograins.Meanwhile,the Cu-rich precipitates in the matrix are also broken and refined under the action of large rolling stress.In the process of cryogenic rolling,the tensile strength and hardness of SF-7055 Al alloy gradually increase,while the plasticity decreases.Moreover,the fracture morphology of cryogenic rolled SF-7055 Al alloy gradually transforms to the ductile and quasi-cleavage hybrid fracture characteristics with increased reduction.展开更多
The microstructure of high Nb-TiAl alloys was optimized by the addition of a small amount of Ta elements to further improve their properties.A series of Ti46Al1.5Cr8Nb-xTa(x=0.2,0.4,0.6,0.8,1.0,at.%)alloys were prepar...The microstructure of high Nb-TiAl alloys was optimized by the addition of a small amount of Ta elements to further improve their properties.A series of Ti46Al1.5Cr8Nb-xTa(x=0.2,0.4,0.6,0.8,1.0,at.%)alloys were prepared by vacuum arc melting.The microstructure,mechanical properties,and related influencing mechanisms were systematically investigated.The results indicate that the solidification microstructure of the Ti46Al1.5Cr8Nb-xTa alloys comprises theγ-TiAl phase,α_(2)-Ti_(3)Al phase,and B2 phase.As the Ta content increases from 0.2 at.%to 1.0 at.%,the content ofα_(2)phase and B2 phase increases,while theγphase content decreases.Among them,the B2 phase shows the most pronounced change,being significantly refined,with its content increasing from 12.49%to 21.91%.In addition,the average size of the lamellar colony decreases from 160.65 to 94.44μm.The addition of the Ta element shifts the solidification path toward lower aluminum concentrations,leading to changes in phase content.The tantalum-induced increase in the B2 phase and enhanced supercooling at the solidification front provide the basis for lamellar colony refinement.Compressive testing at room temperature reveals that the Ti46 Al1.5 Cr8 Nb0.4 Ta alloy exhibits optimal compressive properties,achieving a compressive strength of 2,434 MPa and a compressive strain of 33.1%.The improvement of its properties is attributed to a combination of lamellar colony refinement,solid solution strengthening resulting from the incorporation of Ta element,and a reduction in the c/a of theγphase.展开更多
Developing precision forming of magnesium alloy micro-grooved heat pipes is of great significance for improving the lightweight level of aerospace thermal management systems.In this paper,the electrically-assisted ext...Developing precision forming of magnesium alloy micro-grooved heat pipes is of great significance for improving the lightweight level of aerospace thermal management systems.In this paper,the electrically-assisted extrusion of magnesium alloy heat pipes is explored,and the effects of extrusion and electrical parameters on the forming accuracy,microstructures,and mechanical properties are studied.Finite element simulation found that electrifying the extrusion ram and preheating the extrusion cylinder could effectively ensure the billet temperature,and an extrusion window(30-60 s)could be obtained.Reducing the extrusion velocity and increasing the current could both reduce the extrusion load.Within the range of the studied parameters,the micro-grooved heat pipes are relatively fully formed.It is found that increasing the extrusion velocity and electrical parameters would increase the grain size of the magnesium alloy.While the electrical parameter increases from 0 to 300 A,the grain size increases from~5.9 to~12.6μm,and the tensile strength and yield strength of the extruded profiles are also 20.7%and 16.8%lower than those without current.The tensile fracture surface shows that under the parameters of high extrusion velocity and high current,the fracture morphology changes from dimples and cleavage planes to large-area river patterns,and the fracture mode changes from the mixed ductile-brittle fracture to the brittle fracture.Under the extrusion parameters of 0.5 mm/s and 100 A,the extrusion load is reduced by 1.0-1.6 T,the cross-sectional filling rate is as high as 97.5%,and the size deviation of the micro-ribs(0.8 mm)is only±5μm.Simultaneously,under these parameters,the grain size does not significantly coarsen,and the strength and plasticity of the heat pipe increase slightly.This work provides theoretical and technical support for the development of precision forming technology of lightweight aerospace heat pipes.展开更多
Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of re...Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of recycled coral aggregate on concrete properties,this study performed a comprehensive analysis of the physical properties of recycled coral aggregate and the basic mechanical properties and microstructure of RCAC.The test results indicate that,compared to coral debris,the crushing index of recycled coral aggregate was reduced by 9.4%,while porosity decreased by 33.5%.Furthermore,RCAC retained the early strength characteristics of coral concrete,with compressive strength and flexural strength exhibiting a notable increase as the water-cement ratio decreased.Under identical conditions,the compressive strength and flexural strength of RCAC were 12.7% and 2.5% higher than coral concrete's,respectively,with porosity correspondingly reduced from 3.13% to 5.11%.This enhancement could be attributed to the new mortar filling the recycled coral aggregate.Scanning electron microscopy(SEM)analysis revealed three distinct interface transition zones within RCAC,with the‘new mortar-old mortar’interface identified as the weakest.The above findings provided a reference for the sustainable use of coral concrete in constructing offshore islands.展开更多
A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface,which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate.The resu...A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface,which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate.The results show that cold-pressing produces intense plastic deformation near the corrugated surface of the Al plate,which promotes dynamic recrystallization of the Al substrate near the interface during the subsequent hot-pressing.In addition,the initial corrugation on the surface of the Al plate also changes the local stress state near the interface during hot pressing,which has a large effect on the texture components of the substrates near the corrugated interface.The construction of the corrugated interface can greatly enhance the shear strength by 2−4 times due to the increased contact area and the strong“mechanical gearing”effect.Moreover,the mechanical properties are largely depended on the orientation relationship between corrugated direction and loading direction.展开更多
High entropy alloys(HEAs)have recently attracted significant attention due to their exceptional mechanical properties and potential applications across various fields.Friction stir welding and processing(FSW/P),as not...High entropy alloys(HEAs)have recently attracted significant attention due to their exceptional mechanical properties and potential applications across various fields.Friction stir welding and processing(FSW/P),as notable solid-state welding and processing techniques,have been proved effectiveness in enhancing microstructures and mechanical properties of HEAs.This review article summarizes the current status of FSW/P of HEAs.The welding materials and conditions used for FSW/P in HEAs are reviewed and discussed.The effects of FSW/P on the evolutions of grain structure,texture,dislocation,and secondary phase for different HEAs are highlighted.Furthermore,the influences of FSW/P on the mechanical properties of various HEAs are analyzed.Finally,potential applications,challenges,and future directions of FSW/P in HEAs are forecasted.Overall,FSW/P enable to refine grains of HEAs through dynamic recrystallization and to activate diverse deformation mechanisms of HEAs through tailoring phase structures,thereby significantly improving the strength,hardness,and ductility of both single-and dual-phase HEAs.Future progress in this field will rely on comprehensive optimization of processing parameters and alloy composition,integration of multi-scale modeling with advanced characterization for in-depth exploration of microstructural mechanisms,systematic evaluation of functional properties,and effective bridging of the gap between laboratory research and industrial application.The review aims to provide an overview of recent advancements in the FSW/P of HEAs and encourage further research in this area.展开更多
The use of high entropy alloy as a binder for tungsten heavy alloys offers potential advantages.The 95W-5CoCrFeMnNi alloys(95W-HEAs)were prepared via powder metallurgy at sintering temperatures of 1400−1550℃.The micr...The use of high entropy alloy as a binder for tungsten heavy alloys offers potential advantages.The 95W-5CoCrFeMnNi alloys(95W-HEAs)were prepared via powder metallurgy at sintering temperatures of 1400−1550℃.The microstructure analysis revealed that the tungsten phase in 95W-HEAs exhibited a nearly spherical morphology in the HEA binder matrix and the formation of a Cr−Mn oxide mixed phase was observed.The sintering temperature exerted a significant influence on the relative density,grain size,W−W contiguity,and mechanical properties of the alloys.The optimal performance was achieved when sintering at 1450℃,yielding a relative density of 96.61%,a W−W contiguity of 0.528,an average grain size of 18.97μm,a compressive strength of 2234.82 MPa,and a hardness of HV 400.6.The activation energy for the diffusion of tungsten in the liquid phase formed by HEA binder was calculated to be 354.514 kJ/mol,highlighting its role in controlling grain growth.展开更多
To investigate the aging mechanisms and elucidate the correlations between unstable microstructure and performance in biodegradable Zn alloys,the accelerated aging experiment was conducted on a high-performance wrough...To investigate the aging mechanisms and elucidate the correlations between unstable microstructure and performance in biodegradable Zn alloys,the accelerated aging experiment was conducted on a high-performance wrought Zn−0.1Mg alloy by annealing at 200℃ for varying durations.The findings reveal that the tensile strength of the alloy rapidly and significantly declines with prolonged annealing time,decreasing from 383 MPa for the as-received alloy to 102 MPa for the alloy subjected to 1440 min of annealing.The primary factors contributing to this considerable reduction in strength are static recrystallization,grain coarsening,and dislocation annihilation.Initially,the ductility of the alloy shows fluctuations,ultimately experiencing a marked decrease after extended annealing.This decline is linked to the grain growth and heightened texture intensity,while the unusual increase in ductility observed between 30 and 120 min of annealing is likely due to the formation of twins.In addition,due to rapid grain growth and an increase in precipitates and twins,the corrosion resistance of the alloy in Hank’s solution has worsened,with the corrosion rate rising from 0.037 to 0.069 mm/a following 300 min of annealing.展开更多
The densification characterization,phase constitution,precipitation evolution and mechanical performance of Al−Mg−Sc−Zr alloy processed by laser powder bed fusion(LPBF)were systematically investigated.Moreover,the evo...The densification characterization,phase constitution,precipitation evolution and mechanical performance of Al−Mg−Sc−Zr alloy processed by laser powder bed fusion(LPBF)were systematically investigated.Moreover,the evolution of phase constitution and precipitation behavior after heat treatment were characterized by using X-ray diffraction(XRD)and transmission electron microscope(TEM)analysis.The ultimate tensile strength(UTS)of as-built samples ranged from 396.8 to 414.6 MPa as the scanning speed decreased from 1600 to 1000 mm/s.After post heat treatment,the yield strength(YS)increased to(513.1±1.3)MPa,while the UTS increased from(414.6±5.1)to(539.2±1.5)MPa.The significant improvement of mechanical performance was ascribed to the formation of secondary Al3(Sc,Zr)precipitates.展开更多
The impact of Mn addition on the microstructure,mechanical properties and corrosion behavior of T6-treated Al−Si−Mg−xMn(x=0.2−1.0 wt.%)alloys in a 3.5 wt.%NaCl solution was investigated.The results showed that adding ...The impact of Mn addition on the microstructure,mechanical properties and corrosion behavior of T6-treated Al−Si−Mg−xMn(x=0.2−1.0 wt.%)alloys in a 3.5 wt.%NaCl solution was investigated.The results showed that adding 0.2 wt.%Mn to T6-treated Al−Si−Mg alloys enhanced the corrosion resistance by promoting the formation ofα-AlFeMnSi phase,characterized by smaller absolute Volta potential values compared to eutectic Si,β-AlFeSi andπ-AlFeMgSi phases.However,the addition of 0.5 wt.%Mn and 1.0 wt.%Mn to the T6-treated Al−Si−Mg alloys increased the size of theα-AlFeMnSi phase.This decreased the properties of T6-treated Al−Si−Mg alloys.Therefore,the optimum Mn content was 0.2 wt.%,providing a novel approach for synergistically enhancing mechanical properties and corrosion resistance of Al−Si−Mg alloys.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
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
Modification of 6061 aluminum alloy was conducted through composite addition of cerium-rich rare earths and Al-Ti-B.Results show that the composite addition of Al-Ti-B and Ce/La element at a specific ratio notably pro...Modification of 6061 aluminum alloy was conducted through composite addition of cerium-rich rare earths and Al-Ti-B.Results show that the composite addition of Al-Ti-B and Ce/La element at a specific ratio notably promotes the refinement of the alloy's grains.Ce and La elements are combined with Si and other elements to form rare earth phases,improving the morphology and distribution of precipitates and mitigating the adverse effects ofβ-Fe phases on the microstructure and mechanical properties of alloy.However,excessive rare earth content poses challenges;it not only leads to a decrease in Mg-Si strengthening phase by binding with Si but also promotes the formation of larger or numerous rare earth phases that may act as initiation points for cracks,thereby impeding the improvement of the structure and performance of alloy.The composite addition of cerium-rich rare earths and Al-Ti-B not only preserves the strength of the alloy but also significantly enhances the plasticity of the 6061 as-cast alloy.At a composite addition ratio of Al-Ti-B:RE=2:1,the newly developed 6061-RE aluminum alloy exhibits increased average elongation by 50%and 45%in its as-cast and homogenized states,respectively,compared to the baseline 6061 alloy,facilitating subsequent deformation processing.After solution treatment at 540℃for 1 h and aging at 180℃for 5 h,the average ultimate tensile strength and yield strength of 6061-RE alloys reach 313.2 and 283.1 MPa,increased by 12.3%and 14.5%compared with those of the original alloy,respectively,and the average elongation is improved by 41%.展开更多
Metamaterials programmed with target rate-dependent mechanical properties are efficient platforms for realizing advanced functionalities.Yet,the loading rate-dependent mechanical property programming has received limi...Metamaterials programmed with target rate-dependent mechanical properties are efficient platforms for realizing advanced functionalities.Yet,the loading rate-dependent mechanical property programming has received limited attention.Here,the“stair-building”strategy is employed in the rate domain by combining the bistability with viscoelasticity.An arbitrary target curve in the programmable space can be approximated by a“stair”built by two kinds of“bricks”.The“bricks”can be realized by a dual-bistable unit,constructed by two bistable structures in series.The dual-bistable unit can switch between two efficient stable phases without inducing changes in the global morphology.Such a unit exhibits N-shaped stress-strain curves at both efficient stable phases with different peak values,resulting in different heights of“bricks”.Moreover,the N-shaped curves have rate-dependent peak values,indicating that the heights of“bricks”change with loading rate.The“stair-building”strategy is realized by array-structured mechanical metamaterials based on dual-bistable units.Different stress-strain curves under various loading rates can be reprogrammed in the same piece of metamaterial by intentionally selecting the efficient stable phases of units.Besides,the rate effect of the metamaterial can also be tuned by reprogramming stress-strain curves under both low and high loading rates,respectively.This reprogrammable metamaterial is promising in smart vibration isolators and adaptive energy absorbers.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 functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ...The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ simulations with varied protocols to evaluate the effectiveness of different descriptors in predicting mechanical properties across both low-and high-pressure regimes.Our findings demonstrate that conventional structural and configurational descriptors fail to correlate with the mechanical response following pressure release,whereas the activation energy descriptor exhibits robust linearity with shear modulus after correcting for pressure effects.Notably,the soft mode parameter emerges as an ideal and computationally efficient alternative for capturing this mechanical behavior.These findings provide critical insights into the influence of pressure on glassy properties,integrating the distinct features of compressed glasses into a unified theoretical framework.展开更多
Cells interact with the extracellular matrix and generate traction forces,which play fundamental roles in many cytological activities,such as migration and differentiation.The quanti fication of these traction forces ...Cells interact with the extracellular matrix and generate traction forces,which play fundamental roles in many cytological activities,such as migration and differentiation.The quanti fication of these traction forces is a prerequisite for understanding the interaction and regulation between force and functions,which can be accomplished by traction force microscopy(TFM).In TFM,the forces are determined by tracking the displacement of fiducial markers through optical microscopy.The type of fiducial marker,microscopy modality,and image processing algorithms are key factors determining the final resolution of TFM.This review summarizes efforts in three aspects to enhance the performance of TFM and discusses the challenges of further development,particularly from an optical view.展开更多
基金National Natural Science Foundation of China(52172108)National Key R&D Program of China(2022YFB3707700)Strategic Priority Research Program of the Chinese Academy of Sciences(XDC0144005)。
文摘Silicon carbide fibers are considered ideal reinforcing materials for ceramic matrix composites due to their excellent mechanical properties and high-temperature performance.Different types of fibers necessitate individual investigation due to variations in their composition and fabrication processes.This study presents a comprehensive investigation into evolution of the mechanical properties,surface microstructure,and composition of Shicolon-Ⅱ fibers subjected to argon heat treatment at temperatures ranging from 1300℃to 1700℃.The Shicolon-Ⅱ fibers are composed of small-sized β-SiC grains,SiC_(x)O_(y) amorphous phase,and a minor amount of graphite microcrystals.Following treatment in an argon atmosphere at 1300℃,the fibers maintain a monofilament tensile strength of 3.620 GPa,corresponding to a retention of 98.32%.This strength diminishes to 2.875 GPa,equating to a retention of 78.08%,after treatment at 1500℃.The reduction in mechanical properties of the fibers can be ascribed to the decomposition of the amorphous phase and the growth of β-SiC grains.Furthermore,creep resistance is an essential factor influencing the long-term performance of composite materials.After treatment at temperatures above 1400℃,the high-temperature creep resistance of the fibers is significantly enhanced due to growth of β-SiC grains.This study offers valuable theoretical insights into high-temperature applications of second-generation fibers,contributing to an enhanced understanding of their performance under extreme conditions.
基金Tianjin Municipal Natural Science Foundation(23JCYBJC00040)National Natural Science Foundation of China(52175369)。
文摘The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solution were used to regulate the microstructure,mechanical properties,and corrosion properties of B_(4)C/TC4 composite.Results show that with the increase in temperature from 500℃to 800°C,partial lamellarα-Ti in the as-deposited sample is gradually transformed into equiaxedα-Ti,accompanied by the disappearance of basketweave microstructure.At 1100°C,a small portion of TiC phase suffers fusion.This composite exhibits the optimal combination of strength and plasticity after annealing at 500℃for 4 h followed by furnace cooling,which is attributed to the stress release effect and the refined basketweave microstructure.However,this composite shows a decline in corrosion resistance after various heat treatments due to grain coarsening and micro-galvanic corrosion.
基金financially and technically supported by the National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact,Beijing Institute of Technology,China(No.WDZC2024-1)。
文摘Cryogenic rolling impacts on microstructure and mechanical properties of spray-formed 7055(SF-7055)Al alloy were investigated.Results show that with the increase of the reduction from 20%to 80%,the grain of cryogenic rolled SF-7055 Al alloy is elongated to form a fiber texture.Numerous proliferating dislocations in the microstructure accumulate into dislocation walls and cells,and eventually form subgrains.These subgrain boundaries divide the original grain,thereby reducing the grain size.Under severe deformation conditions,they even enable the formation of nanograins.Meanwhile,the Cu-rich precipitates in the matrix are also broken and refined under the action of large rolling stress.In the process of cryogenic rolling,the tensile strength and hardness of SF-7055 Al alloy gradually increase,while the plasticity decreases.Moreover,the fracture morphology of cryogenic rolled SF-7055 Al alloy gradually transforms to the ductile and quasi-cleavage hybrid fracture characteristics with increased reduction.
基金the financial support by the Major Science and Technology Achievement Transformation Project in Heilongjiang Province(No.ZC2023SH0075)the National Natural Science Foundation of China(Nos.52425401,U2441255,52474377,and 52371015)+1 种基金the Young Elite Scientists Sponsorship·Program by CAST(No.2021QNRC001)the Henan Provincial Key Research and Development&Promotion Special Program(No.251111231400)。
文摘The microstructure of high Nb-TiAl alloys was optimized by the addition of a small amount of Ta elements to further improve their properties.A series of Ti46Al1.5Cr8Nb-xTa(x=0.2,0.4,0.6,0.8,1.0,at.%)alloys were prepared by vacuum arc melting.The microstructure,mechanical properties,and related influencing mechanisms were systematically investigated.The results indicate that the solidification microstructure of the Ti46Al1.5Cr8Nb-xTa alloys comprises theγ-TiAl phase,α_(2)-Ti_(3)Al phase,and B2 phase.As the Ta content increases from 0.2 at.%to 1.0 at.%,the content ofα_(2)phase and B2 phase increases,while theγphase content decreases.Among them,the B2 phase shows the most pronounced change,being significantly refined,with its content increasing from 12.49%to 21.91%.In addition,the average size of the lamellar colony decreases from 160.65 to 94.44μm.The addition of the Ta element shifts the solidification path toward lower aluminum concentrations,leading to changes in phase content.The tantalum-induced increase in the B2 phase and enhanced supercooling at the solidification front provide the basis for lamellar colony refinement.Compressive testing at room temperature reveals that the Ti46 Al1.5 Cr8 Nb0.4 Ta alloy exhibits optimal compressive properties,achieving a compressive strength of 2,434 MPa and a compressive strain of 33.1%.The improvement of its properties is attributed to a combination of lamellar colony refinement,solid solution strengthening resulting from the incorporation of Ta element,and a reduction in the c/a of theγphase.
基金supported by the National Natural Science Foundation of China(Grant Nos.U24B2056,52505361)China Postdoctoral Science Foundation(Grant No.2025M774308)。
文摘Developing precision forming of magnesium alloy micro-grooved heat pipes is of great significance for improving the lightweight level of aerospace thermal management systems.In this paper,the electrically-assisted extrusion of magnesium alloy heat pipes is explored,and the effects of extrusion and electrical parameters on the forming accuracy,microstructures,and mechanical properties are studied.Finite element simulation found that electrifying the extrusion ram and preheating the extrusion cylinder could effectively ensure the billet temperature,and an extrusion window(30-60 s)could be obtained.Reducing the extrusion velocity and increasing the current could both reduce the extrusion load.Within the range of the studied parameters,the micro-grooved heat pipes are relatively fully formed.It is found that increasing the extrusion velocity and electrical parameters would increase the grain size of the magnesium alloy.While the electrical parameter increases from 0 to 300 A,the grain size increases from~5.9 to~12.6μm,and the tensile strength and yield strength of the extruded profiles are also 20.7%and 16.8%lower than those without current.The tensile fracture surface shows that under the parameters of high extrusion velocity and high current,the fracture morphology changes from dimples and cleavage planes to large-area river patterns,and the fracture mode changes from the mixed ductile-brittle fracture to the brittle fracture.Under the extrusion parameters of 0.5 mm/s and 100 A,the extrusion load is reduced by 1.0-1.6 T,the cross-sectional filling rate is as high as 97.5%,and the size deviation of the micro-ribs(0.8 mm)is only±5μm.Simultaneously,under these parameters,the grain size does not significantly coarsen,and the strength and plasticity of the heat pipe increase slightly.This work provides theoretical and technical support for the development of precision forming technology of lightweight aerospace heat pipes.
基金Funded by Natural Science Foundation of Guangxi(No.2025GXNSFBA069565)Guangxi Science and Technology Program(No.AD25069101)Guangxi Bagui Scholars Fund。
文摘Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of recycled coral aggregate on concrete properties,this study performed a comprehensive analysis of the physical properties of recycled coral aggregate and the basic mechanical properties and microstructure of RCAC.The test results indicate that,compared to coral debris,the crushing index of recycled coral aggregate was reduced by 9.4%,while porosity decreased by 33.5%.Furthermore,RCAC retained the early strength characteristics of coral concrete,with compressive strength and flexural strength exhibiting a notable increase as the water-cement ratio decreased.Under identical conditions,the compressive strength and flexural strength of RCAC were 12.7% and 2.5% higher than coral concrete's,respectively,with porosity correspondingly reduced from 3.13% to 5.11%.This enhancement could be attributed to the new mortar filling the recycled coral aggregate.Scanning electron microscopy(SEM)analysis revealed three distinct interface transition zones within RCAC,with the‘new mortar-old mortar’interface identified as the weakest.The above findings provided a reference for the sustainable use of coral concrete in constructing offshore islands.
基金supported by Guangdong Major Project of Basic and Applied Basic Research, China (No. 2020B0301030006)Fundamental Research Funds for the Central Universities, China (No. SWU-XDJH202313)+1 种基金Chongqing Postdoctoral Science Foundation Funded Project, China (No. 2112012728014435)the Chongqing Postgraduate Research and Innovation Project, China (No. CYS23197)。
文摘A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface,which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate.The results show that cold-pressing produces intense plastic deformation near the corrugated surface of the Al plate,which promotes dynamic recrystallization of the Al substrate near the interface during the subsequent hot-pressing.In addition,the initial corrugation on the surface of the Al plate also changes the local stress state near the interface during hot pressing,which has a large effect on the texture components of the substrates near the corrugated interface.The construction of the corrugated interface can greatly enhance the shear strength by 2−4 times due to the increased contact area and the strong“mechanical gearing”effect.Moreover,the mechanical properties are largely depended on the orientation relationship between corrugated direction and loading direction.
基金supported by National Natural Science Foundation of China(Grant No.52171032)Hebei Natural Science Foundation(Grant No.E2023501002)Fundamental Research Funds for the Central Universities(Grant No.2024GFYD003)。
文摘High entropy alloys(HEAs)have recently attracted significant attention due to their exceptional mechanical properties and potential applications across various fields.Friction stir welding and processing(FSW/P),as notable solid-state welding and processing techniques,have been proved effectiveness in enhancing microstructures and mechanical properties of HEAs.This review article summarizes the current status of FSW/P of HEAs.The welding materials and conditions used for FSW/P in HEAs are reviewed and discussed.The effects of FSW/P on the evolutions of grain structure,texture,dislocation,and secondary phase for different HEAs are highlighted.Furthermore,the influences of FSW/P on the mechanical properties of various HEAs are analyzed.Finally,potential applications,challenges,and future directions of FSW/P in HEAs are forecasted.Overall,FSW/P enable to refine grains of HEAs through dynamic recrystallization and to activate diverse deformation mechanisms of HEAs through tailoring phase structures,thereby significantly improving the strength,hardness,and ductility of both single-and dual-phase HEAs.Future progress in this field will rely on comprehensive optimization of processing parameters and alloy composition,integration of multi-scale modeling with advanced characterization for in-depth exploration of microstructural mechanisms,systematic evaluation of functional properties,and effective bridging of the gap between laboratory research and industrial application.The review aims to provide an overview of recent advancements in the FSW/P of HEAs and encourage further research in this area.
基金supported by the National Natural Science Foundation of China(No.51874368)。
文摘The use of high entropy alloy as a binder for tungsten heavy alloys offers potential advantages.The 95W-5CoCrFeMnNi alloys(95W-HEAs)were prepared via powder metallurgy at sintering temperatures of 1400−1550℃.The microstructure analysis revealed that the tungsten phase in 95W-HEAs exhibited a nearly spherical morphology in the HEA binder matrix and the formation of a Cr−Mn oxide mixed phase was observed.The sintering temperature exerted a significant influence on the relative density,grain size,W−W contiguity,and mechanical properties of the alloys.The optimal performance was achieved when sintering at 1450℃,yielding a relative density of 96.61%,a W−W contiguity of 0.528,an average grain size of 18.97μm,a compressive strength of 2234.82 MPa,and a hardness of HV 400.6.The activation energy for the diffusion of tungsten in the liquid phase formed by HEA binder was calculated to be 354.514 kJ/mol,highlighting its role in controlling grain growth.
基金supported by the National Natural Science Foundation of China(No.52271101)Suzhou Science and Technology Project,China(Nos.SYG202312,SJC2023005,SZS2023023)+1 种基金Nanjing Major Science and Technology Project,China(No.202309015)the Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology,China(No.ASMA202305)。
文摘To investigate the aging mechanisms and elucidate the correlations between unstable microstructure and performance in biodegradable Zn alloys,the accelerated aging experiment was conducted on a high-performance wrought Zn−0.1Mg alloy by annealing at 200℃ for varying durations.The findings reveal that the tensile strength of the alloy rapidly and significantly declines with prolonged annealing time,decreasing from 383 MPa for the as-received alloy to 102 MPa for the alloy subjected to 1440 min of annealing.The primary factors contributing to this considerable reduction in strength are static recrystallization,grain coarsening,and dislocation annihilation.Initially,the ductility of the alloy shows fluctuations,ultimately experiencing a marked decrease after extended annealing.This decline is linked to the grain growth and heightened texture intensity,while the unusual increase in ductility observed between 30 and 120 min of annealing is likely due to the formation of twins.In addition,due to rapid grain growth and an increase in precipitates and twins,the corrosion resistance of the alloy in Hank’s solution has worsened,with the corrosion rate rising from 0.037 to 0.069 mm/a following 300 min of annealing.
基金support of the Research and Development Program in Key Areas of Guangdong Province,China(No.2019B090907001)the Science and Technology Program of Guangdong Province,China(No.2014B010129002)the National Key R&D Program of China(No.2017YFB0305800)。
文摘The densification characterization,phase constitution,precipitation evolution and mechanical performance of Al−Mg−Sc−Zr alloy processed by laser powder bed fusion(LPBF)were systematically investigated.Moreover,the evolution of phase constitution and precipitation behavior after heat treatment were characterized by using X-ray diffraction(XRD)and transmission electron microscope(TEM)analysis.The ultimate tensile strength(UTS)of as-built samples ranged from 396.8 to 414.6 MPa as the scanning speed decreased from 1600 to 1000 mm/s.After post heat treatment,the yield strength(YS)increased to(513.1±1.3)MPa,while the UTS increased from(414.6±5.1)to(539.2±1.5)MPa.The significant improvement of mechanical performance was ascribed to the formation of secondary Al3(Sc,Zr)precipitates.
基金supported by the National Key Research and Development Program of China(No.2022YFB3404202)the National Natural Science Foundation of China(No.52271103)the Jilin Scientific and Technological Development Program,China(Nos.20220301026GX,20210301041GX)。
文摘The impact of Mn addition on the microstructure,mechanical properties and corrosion behavior of T6-treated Al−Si−Mg−xMn(x=0.2−1.0 wt.%)alloys in a 3.5 wt.%NaCl solution was investigated.The results showed that adding 0.2 wt.%Mn to T6-treated Al−Si−Mg alloys enhanced the corrosion resistance by promoting the formation ofα-AlFeMnSi phase,characterized by smaller absolute Volta potential values compared to eutectic Si,β-AlFeSi andπ-AlFeMgSi phases.However,the addition of 0.5 wt.%Mn and 1.0 wt.%Mn to the T6-treated Al−Si−Mg alloys increased the size of theα-AlFeMnSi phase.This decreased the properties of T6-treated Al−Si−Mg alloys.Therefore,the optimum Mn content was 0.2 wt.%,providing a novel approach for synergistically enhancing mechanical properties and corrosion resistance of Al−Si−Mg alloys.
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Subproject of Inner Mongolia Autonomous Region Key Research and Development and Achievement Transformation Plan Project(2023YFDZ0064,2023KJHZ0020,2022YFDZ0097)Natural Science Foundation of Inner Mongolia Autonomous Region of China(2022QN05040)+1 种基金Basic Research Funds for Directly Affiliated Universities in Inner Mongolia Autonomous Region(JY20220093)Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(NJYT24008)。
文摘Modification of 6061 aluminum alloy was conducted through composite addition of cerium-rich rare earths and Al-Ti-B.Results show that the composite addition of Al-Ti-B and Ce/La element at a specific ratio notably promotes the refinement of the alloy's grains.Ce and La elements are combined with Si and other elements to form rare earth phases,improving the morphology and distribution of precipitates and mitigating the adverse effects ofβ-Fe phases on the microstructure and mechanical properties of alloy.However,excessive rare earth content poses challenges;it not only leads to a decrease in Mg-Si strengthening phase by binding with Si but also promotes the formation of larger or numerous rare earth phases that may act as initiation points for cracks,thereby impeding the improvement of the structure and performance of alloy.The composite addition of cerium-rich rare earths and Al-Ti-B not only preserves the strength of the alloy but also significantly enhances the plasticity of the 6061 as-cast alloy.At a composite addition ratio of Al-Ti-B:RE=2:1,the newly developed 6061-RE aluminum alloy exhibits increased average elongation by 50%and 45%in its as-cast and homogenized states,respectively,compared to the baseline 6061 alloy,facilitating subsequent deformation processing.After solution treatment at 540℃for 1 h and aging at 180℃for 5 h,the average ultimate tensile strength and yield strength of 6061-RE alloys reach 313.2 and 283.1 MPa,increased by 12.3%and 14.5%compared with those of the original alloy,respectively,and the average elongation is improved by 41%.
基金supported by the National Natural Science Foundation of China(Grant Nos.12225201,12372126,12002016,and 12172026)the National Key Research and Development Program of China(Grant No.2020YFB1313003)the Fundamental Research Funds for the Central Universities are gratefully acknowledged.
文摘Metamaterials programmed with target rate-dependent mechanical properties are efficient platforms for realizing advanced functionalities.Yet,the loading rate-dependent mechanical property programming has received limited attention.Here,the“stair-building”strategy is employed in the rate domain by combining the bistability with viscoelasticity.An arbitrary target curve in the programmable space can be approximated by a“stair”built by two kinds of“bricks”.The“bricks”can be realized by a dual-bistable unit,constructed by two bistable structures in series.The dual-bistable unit can switch between two efficient stable phases without inducing changes in the global morphology.Such a unit exhibits N-shaped stress-strain curves at both efficient stable phases with different peak values,resulting in different heights of“bricks”.Moreover,the N-shaped curves have rate-dependent peak values,indicating that the heights of“bricks”change with loading rate.The“stair-building”strategy is realized by array-structured mechanical metamaterials based on dual-bistable units.Different stress-strain curves under various loading rates can be reprogrammed in the same piece of metamaterial by intentionally selecting the efficient stable phases of units.Besides,the rate effect of the metamaterial can also be tuned by reprogramming stress-strain curves under both low and high loading rates,respectively.This reprogrammable metamaterial is promising in smart vibration isolators and adaptive energy absorbers.
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 the National Natural Science Foundation of China (Grant Nos.T2325004 and 52161160330)the National Natural Science Foundation of China (Grants No.12504233)+2 种基金Advanced MaterialsNational Science and Technology Major Project (Grant No.2024ZD0606900)the Talent Hub for “AI+New Materials” Basic Researchthe Key Research and Development Program of Ningbo (Grant No.2025Z088)。
文摘The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ simulations with varied protocols to evaluate the effectiveness of different descriptors in predicting mechanical properties across both low-and high-pressure regimes.Our findings demonstrate that conventional structural and configurational descriptors fail to correlate with the mechanical response following pressure release,whereas the activation energy descriptor exhibits robust linearity with shear modulus after correcting for pressure effects.Notably,the soft mode parameter emerges as an ideal and computationally efficient alternative for capturing this mechanical behavior.These findings provide critical insights into the influence of pressure on glassy properties,integrating the distinct features of compressed glasses into a unified theoretical framework.
基金supported by the Major Research Instrument Development Project of the National Natural Science Foundation of China(32527801)the National Natural Science Foundation of China(32301168)+1 种基金the Ningbo Natural Science Foundation of China(2023J351)the Yongjiang Innovative Talents Project of Ningbo City(2024A-172-G).
文摘Cells interact with the extracellular matrix and generate traction forces,which play fundamental roles in many cytological activities,such as migration and differentiation.The quanti fication of these traction forces is a prerequisite for understanding the interaction and regulation between force and functions,which can be accomplished by traction force microscopy(TFM).In TFM,the forces are determined by tracking the displacement of fiducial markers through optical microscopy.The type of fiducial marker,microscopy modality,and image processing algorithms are key factors determining the final resolution of TFM.This review summarizes efforts in three aspects to enhance the performance of TFM and discusses the challenges of further development,particularly from an optical view.
