Articular cartilage maintains joint homeostasis by adapting to mechanical loading,but both insufficient and excessive loading can impair cartilage integrity.Whether mechanical activity should be restricted in early os...Articular cartilage maintains joint homeostasis by adapting to mechanical loading,but both insufficient and excessive loading can impair cartilage integrity.Whether mechanical activity should be restricted in early osteoarthritis(OA),particularly among exercise enthusiasts,remains controversial.Here,we established in vitro and in vivo models of prolonged moderate mechanical loading(7.5%strain,1 Hz)and analyzed human cartilage from weight-bearing and non-weight-bearing regions using RNA sequencing.Prolonged exposure(≥12 h)significantly increased chondrocyte apoptosis(2.3-fold),reduced expression of the chondrogenic transcription factor SOX9 and the matrix markers COL2A1,and elevated nerve growth factor(NGF)expression(1.8-fold),accompanied by enrichment of neural sensitization and inflammatory pathways.Immunofluorescence staining revealed NGF accumulation in mechanically stressed cartilage.Unlike high-intensity stress,which led to immediate apoptosis,moderate loading induced a delayed pro-apoptotic response after 12 h.These findings indicate that prolonged moderate mechanical loading may promote chondrocyte apoptosis through an NGFmediated inflammatory microenvironment and provide mechanistic evidence suggesting that patients with early OA may benefit from limiting high-impact or prolonged moderate-intensity exercise sessions to prevent cartilage damage and guide rehabilitation.展开更多
The effects of channel segregation on the macro-and micro-scale chemical composition,microstructure,hardness,and tensile deformation behavior of Ti45Nb wires were investigated.The results show that wires with severe c...The effects of channel segregation on the macro-and micro-scale chemical composition,microstructure,hardness,and tensile deformation behavior of Ti45Nb wires were investigated.The results show that wires with severe channel segregation exhibit a macroscopic chemical composition identical to those without segregation,and 3D X-ray imaging result also reveals no abnormalities.After annealing,both types of wires exhibit an equiaxed single-phase microstructure with comparable grain sizes,suggesting that channel segregation has negligible influence on the macroscopic composition and grain size.Metallographic examination reveals that channel segregation manifests as spot-like features in the transverse section and band-like structures in the longitudinal section.EDS analysis identifies these regions as Ti-enriched segregations,with a Ti content higher than that of the surrounding matrix by approximately 4.42wt%.Compared to segregation-free wires,those containing extensive channel segregation demonstrate a 15.5%increase in ultimate tensile strength and a 12.3%increase in yield strength,but suffer a reduction in elongation and reduction of area by 19.8%and 18.9%,respectively.Furthermore,the mechanical properties of wires with segregation show significant fluctuations.Fractographic analysis reveals a larger fracture surface area in segregated wires.Severe dislocation pile-ups occur at the interfaces of these segregated regions,initiating microcrack nucleation.This promotes rapid crack propagation of the Ti45Nb wire,leading to a significant decrease in plasticity and reduction of area.展开更多
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 effect of warm rolling temperature(500-900℃)on the microstructure and mechanical properties was investigated for a Ni-W-Co-Ta alloy to achieve excellent strength-plasticity synergy.The results showed that the all...The effect of warm rolling temperature(500-900℃)on the microstructure and mechanical properties was investigated for a Ni-W-Co-Ta alloy to achieve excellent strength-plasticity synergy.The results showed that the alloy exhibited high-density dislocations and deformation bands when rolled below 750℃.The nano-Ni4W phase precipitated when rolled at 700-900℃,with the higher deformation temperature,the amount and size of precipitates increased.At 900℃,dissolution of the precipitated Ni4W and dynamic recrystallization of the matrix occurred.Consequently,the strength and hardness firstly decreased,then increased,and decreased again as the deformation temperature increased.An excellent strength-plasticity synergy was achieved through the combined effects of precipitation strengthening and deformation twins strengthening of Ni4W:with a tensile strength of 2010 MPa,a yield strength of 1839 MPa,a microhardness of HV 587,and an elongation of 13.2%when the alloy was warm-rolled at 750℃.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
To investigate the effects of extrusion temperature on the microstructure and mechanical properties of WE43 magnesium alloy,extrusion experiments were conducted under 330,380,430,and 450℃,and the extrusion ratio was ...To investigate the effects of extrusion temperature on the microstructure and mechanical properties of WE43 magnesium alloy,extrusion experiments were conducted under 330,380,430,and 450℃,and the extrusion ratio was 16.The experimental results indicate that,at a low temperature of 330℃,the alloy precipitates a large amount of second phases rich in Zr elements.Moreover,the texture strength and kernel average misorientation value are the highest,with values of 27.77 and 0.71,respectively.The increase in extrusion temperature leads to a gradual decrease in texture strength and kernel average misorientation value.The strength of the alloy is the highest at an extrusion temperature of 330℃.Its tensile yield stress is 254.7 MPa and ultimate tensile strength is 302.7 MPa,respectively.As the extrusion temperature increases,the strength of the alloy gradually decreases.At an extrusion temperature of 450℃,the tensile yield stress is 181.3 MPa and ultimate tensile strength is 265.7 MPa,respectively.The elongation first increases and then decreases,with an elongation of 20.9%at an extrusion temperature of 330℃.At an extrusion temperature of 430℃,the elongation reaches its maximum value,which is 23.6%.At an extrusion temperature of 450℃,the elongation reaches its lowest value,which is 16.4%.展开更多
The influences of silicon addition to commercially pure magnesium(CP Mg)and cooling rate during solidification on the as-cast microstructure and shear mechanical properties of Mg-Si alloys were systematically investig...The influences of silicon addition to commercially pure magnesium(CP Mg)and cooling rate during solidification on the as-cast microstructure and shear mechanical properties of Mg-Si alloys were systematically investigated.For this purpose,the Mg-0.6Si,Mg-1.34Si,and Mg-3Si(wt%)alloys were considered as hypoeutectic,eutectic,and hypereutectic alloys,respectively.By decreasing the geometrical modulus of the solidifying section(increasing cooling rate),remarkable grain refinement,refining the dendrite arm spacing(DAS),and modification of Mg_(2)Si particles were achieved.Moreover,the grain size was refined via Si addition in the hypoeutectic range,while coarsening of grain size at high Si concentrations was observed.The results of shear punch testing and hardness measurements demonstrated that the ultimate shear strength(USS)and hardness increased by increasing the cooling rate during solidification.Moreover,Si addition generally improved hardness,while the highest USS level was achieved for the eutectic alloy due to the fine grain size and strengthening effect of the eutectic constituent.However,regarding the hypereutectic Mg-3Si alloy that exhibited high hardness,the shear properties were inferior due to the detrimental effect of the primary Mg_(2)Si particles.Finally,the results were discussed with consideration of the relationship between strength and hardness,for which the critical effect of Si was clarified.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
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
Al-Si-Cu-Mg alloy demonstrates a significant age-hardening effect,with its mechanical properties tunable by optimizing the aging parameters.To enhance this effect,the as-cast Al-8.5Si-2Cu-0.9Mg alloy was subjected to ...Al-Si-Cu-Mg alloy demonstrates a significant age-hardening effect,with its mechanical properties tunable by optimizing the aging parameters.To enhance this effect,the as-cast Al-8.5Si-2Cu-0.9Mg alloy was subjected to either single-stage aging at temperatures of 150℃,175℃,200℃,and 225℃for 0.5 h to 20 h;or double-stage aging:involving a first-stage aging treatment at 120℃for 1 h,3 h,5 h,or 7 h,followed by a second-stage aging treatment at 175℃ for 0.5 h to 20 h.The microstructure and mechanical properties were evaluated for samples aged at 175℃/7 h,175℃/10 h,120℃/5 h+175℃/5 h,and 120℃/5 h+175℃/8 h.XRD analysis reveals that the as-cast Al-8.5Si-2Cu-0.9Mg alloy consists of theα-Al,Si,θ-Al_(2)Cu,and Q-Al_(5)Cu_(2)Mg_8Si_6phases.The aging kinetics exhibit a double-peak behavior in both single-stage and double-stage aging processes.Under single-stage aging at 175℃/x h and double-stage aging(120℃/5 h+175℃/x h),the precipitates'size at the first peak is smaller than that at the second peak.Compared with single-stage aging(175℃/7 h),double-stage aging(120℃/5 h+175℃/5 h)produces a finer precipitate in the alloy.Theoretical calculations indicate that the number density and nucleation rate of both the Al_(5)Cu_(2)Mg_8Si_6 and Al_(2)Cu phases are higher during the double-stage aging(120℃/5 h+175℃/5 h)than those during the single-stage aging(175℃/7 h).Additionally,tensile tests at both room temperature and 250℃demonstrate that double-stage aging(120℃/5 h+175℃/5 h)significantly improves the mechanical properties of the alloy compared to single-stage aging(175℃/7 h),suggesting that double-stage aging is more effective for enhancing mechanical properties for this alloy.展开更多
The influence of oscillation amplitude on molten pool thermal history,weld morphology characteristics,microstructural evolution,and mechanical properties during laser oscillating welding of QP980 steel was systematica...The influence of oscillation amplitude on molten pool thermal history,weld morphology characteristics,microstructural evolution,and mechanical properties during laser oscillating welding of QP980 steel was systematically investigated.Results show that laser beam oscillation significantly regulates molten pool thermomechanical behavior through optimized spatial energy distribution,thereby enabling microstructural reconstruction and joint performance enhancement.As the oscillation amplitude increases from 0 to 0.8 mm,the molten pool duration extends to 1.7 times the original value,while peak temperature and average cooling rate decrease by 19%and 39%,respectively.This thermal regulation promotes weld surface width expansion from 0.72 to 1.07 mm.The welding mode undergoes a progressive transition from keyhole mode→transitional mode→conduction mode.This transformation effectively suppresses porosity defects,substantially reducing porosity from 1.8%to 0.15%.Microstructural analysis indicates that oscillation modifies the maximum temperature gradient direction within the molten pool,facilitating preferential growth of coarse columnar grains along the welding centerline to establish load-transfer-favorable crystallographic orientations.The synergistic effects of these factors substantially improve joint mechanical properties:lap joint shear load increases by 81.5%(7.6→13.8 kN),and fracture elongation is enhanced by 135%(0.98→2.3 mm).The operational principles of laser oscillation parameters on the welding quality of QP980 steel were elucidated,providing theoretical foundations for joining process optimization.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
Osteoarthritis(OA),the most common chronic joint disease,leads to remarkable morbidity and disability.The development of preclinical models that accurately recapitulate the bio-chemo-mechanical microenvironment of ost...Osteoarthritis(OA),the most common chronic joint disease,leads to remarkable morbidity and disability.The development of preclinical models that accurately recapitulate the bio-chemo-mechanical microenvironment of osteoarthritic joints is crucial for elucidating OA pathogenesis and facilitating drug development.In this study,we present a microfluidics-based cartilage-on-a-chip model that integrates tunable mechanical stimulation and inter-tissue/cell communication,mimicking the key physiological characteristics of articular cartilage for organ-level OA research.By applying controllable mechanical compression,we established a model that captures healthy and injury hallmarks of the cartilage and directly observed the mechanotransduction responses in chondrocytes.We further demonstrated that mechanically damaged cartilage induces synovial abnormalities and immune dysregulation and explored the potential of our chip as a platform for screening therapeutic targets.This cartilage-on-a-chip offers an in vitro system with a close-to-in vivo microenvironment for investigating complex bio-chemo-mechanical interactions,paving the way for advanced studies on OA pathogenesis and drug screening.展开更多
Inconel 625 alloy components were fabricated using hot wire laser metal deposition(HW-LMD)through process optimization,achieving a wire deposition rate of 1.72 kg/h.The microstructure and mechanical properties of the ...Inconel 625 alloy components were fabricated using hot wire laser metal deposition(HW-LMD)through process optimization,achieving a wire deposition rate of 1.72 kg/h.The microstructure and mechanical properties of the HW-LMD Inconel 625 alloys were systematically investigated.The results revealed that the microstructure of the HWLMD Inconel 625 alloys consisted of columnar dendrites,characterized by an average grain size of 12.5μm and a strong{100}〈001〉texture.The main phase identified wasγ-Ni,with the precipitation of Laves phase,measuring less than 1μm,observed in the inter-columnar dendritic regions.The average microhardness of the HW-LMD Inconel 625 alloys was HV1.0258.The yield strength and ultimate tensile strength were 493.5 and 837.4 MPa,respectively,with elongation exceeding 50%.Impact absorbing energies at 25 and-78℃were 223.08 and 200.24 J,respectively.Both the tensile and impact fracture surfaces exhibited dimples,indicating a ductile fracture mechanism during the deformation process.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
W-CoFeNi WHAs(tungsten heavy alloys)were fabricated by powder metallurgy with sintering temperatures ranging from 1480 to 1560℃.The influence of sintering temperatures on microstructure evolutions and mechanical prop...W-CoFeNi WHAs(tungsten heavy alloys)were fabricated by powder metallurgy with sintering temperatures ranging from 1480 to 1560℃.The influence of sintering temperatures on microstructure evolutions and mechanical properties of W-CoFeNi WHAs was investigated.The experimental results show that near-spherical W grains are distributed in CoFeNi ternary multi-principal-elements alloy(MPEA)with the formation of W-richμphase in all W-CoFeNi WHAs.The volume fractions ofμphase and average W grain size increase with sintering temperatures changing from 1480 to 1560℃.The activation energy for W grain growth is significantly higher than that of traditional W-Ni-Fe and W-Ni-Co WHAs,which indicates grain coarsening behavior in CoFeNi MPEA became more difficult compared to the conventional binder alloys.W-CoFeNi sintered at 1480℃exhibits the highest yield strength of 698 MPa among all WHAs due to finer W grain size.The compressive strength and fracture strain of W-CoFeNi reduce when sintering temperatures rise from 1480 to 1560℃.展开更多
Twinning-induced plasticity(TWIP)steel was processed using electrically assisted friction stir welding(EFSW).The microstructure,mechanical properties,and deformation behavior of the welded joints were systematically i...Twinning-induced plasticity(TWIP)steel was processed using electrically assisted friction stir welding(EFSW).The microstructure,mechanical properties,and deformation behavior of the welded joints were systematically investigated.The results show that the average grain size was refined from 3.67μm in the base material(BM)to 1.39μm in the stir zone(SZ),while it increased to 4.19μm in the heat-affected zone(HAZ).The fraction of twin boundaries(TBs)decreased from 20.7%in the BM to 6.9%in the SZ and increased to24.5%in the HAZ.The ultimate tensile strength,yield strength,and elongation of the BM were 1021 MPa,505 MPa,and 65.8%,respectively.In comparison,the EFSW joint exhibited values of 1055 MPa,561 MPa,and 60.8%,corresponding to 103.3%,111.1%,and 92.4%of those of the BM,respectively.During tensile testing,plastic deformation was primarily concentrated in the BM,although both the SZ and HAZ also exhibited notable plastic deformation.Fracture ultimately occurred in the BM.展开更多
基金supported by the Zhejiang Medical and Health Innovation Talent Support Project(Grant No.2021RC128 to S.S.)Zhejiang Medicine and Health Science and Technology Project(2025KY1540 to J.J.L.)+3 种基金Zhejiang Province Health Science and Technology Project(2024KY409 and 2021KY1086 to J.Y.L.)Huzhou Science and Technology Planning Project(2020GY10 to W.L.,2022GZ65 to J.Y.L.)Huzhou Basic and Clinical Translation of Orthopedics Key Laboratory(Grant No.HZGKSYS01Y to S.S.)South Taihu Lake Outstanding Young Health Talents Cultivation Program(Grant No.rsk2023001 to S.S.).
文摘Articular cartilage maintains joint homeostasis by adapting to mechanical loading,but both insufficient and excessive loading can impair cartilage integrity.Whether mechanical activity should be restricted in early osteoarthritis(OA),particularly among exercise enthusiasts,remains controversial.Here,we established in vitro and in vivo models of prolonged moderate mechanical loading(7.5%strain,1 Hz)and analyzed human cartilage from weight-bearing and non-weight-bearing regions using RNA sequencing.Prolonged exposure(≥12 h)significantly increased chondrocyte apoptosis(2.3-fold),reduced expression of the chondrogenic transcription factor SOX9 and the matrix markers COL2A1,and elevated nerve growth factor(NGF)expression(1.8-fold),accompanied by enrichment of neural sensitization and inflammatory pathways.Immunofluorescence staining revealed NGF accumulation in mechanically stressed cartilage.Unlike high-intensity stress,which led to immediate apoptosis,moderate loading induced a delayed pro-apoptotic response after 12 h.These findings indicate that prolonged moderate mechanical loading may promote chondrocyte apoptosis through an NGFmediated inflammatory microenvironment and provide mechanistic evidence suggesting that patients with early OA may benefit from limiting high-impact or prolonged moderate-intensity exercise sessions to prevent cartilage damage and guide rehabilitation.
基金National Natural Science Foundation of China(U24A2038)。
文摘The effects of channel segregation on the macro-and micro-scale chemical composition,microstructure,hardness,and tensile deformation behavior of Ti45Nb wires were investigated.The results show that wires with severe channel segregation exhibit a macroscopic chemical composition identical to those without segregation,and 3D X-ray imaging result also reveals no abnormalities.After annealing,both types of wires exhibit an equiaxed single-phase microstructure with comparable grain sizes,suggesting that channel segregation has negligible influence on the macroscopic composition and grain size.Metallographic examination reveals that channel segregation manifests as spot-like features in the transverse section and band-like structures in the longitudinal section.EDS analysis identifies these regions as Ti-enriched segregations,with a Ti content higher than that of the surrounding matrix by approximately 4.42wt%.Compared to segregation-free wires,those containing extensive channel segregation demonstrate a 15.5%increase in ultimate tensile strength and a 12.3%increase in yield strength,but suffer a reduction in elongation and reduction of area by 19.8%and 18.9%,respectively.Furthermore,the mechanical properties of wires with segregation show significant fluctuations.Fractographic analysis reveals a larger fracture surface area in segregated wires.Severe dislocation pile-ups occur at the interfaces of these segregated regions,initiating microcrack nucleation.This promotes rapid crack propagation of the Ti45Nb wire,leading to a significant decrease in plasticity and reduction of area.
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supported by the National Key Research and Development Program of China(No.2022YFB3705200)the National Natural Science Foundation of China(Nos.U1804146,51905153,52111530068)the Major Science and Technology Project of Henan Province,China(No.221100230200)。
文摘The effect of warm rolling temperature(500-900℃)on the microstructure and mechanical properties was investigated for a Ni-W-Co-Ta alloy to achieve excellent strength-plasticity synergy.The results showed that the alloy exhibited high-density dislocations and deformation bands when rolled below 750℃.The nano-Ni4W phase precipitated when rolled at 700-900℃,with the higher deformation temperature,the amount and size of precipitates increased.At 900℃,dissolution of the precipitated Ni4W and dynamic recrystallization of the matrix occurred.Consequently,the strength and hardness firstly decreased,then increased,and decreased again as the deformation temperature increased.An excellent strength-plasticity synergy was achieved through the combined effects of precipitation strengthening and deformation twins strengthening of Ni4W:with a tensile strength of 2010 MPa,a yield strength of 1839 MPa,a microhardness of HV 587,and an elongation of 13.2%when the alloy was warm-rolled at 750℃.
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Funded by the Fundamental Research Program of Shanxi Province(No.202203021211191)。
文摘To investigate the effects of extrusion temperature on the microstructure and mechanical properties of WE43 magnesium alloy,extrusion experiments were conducted under 330,380,430,and 450℃,and the extrusion ratio was 16.The experimental results indicate that,at a low temperature of 330℃,the alloy precipitates a large amount of second phases rich in Zr elements.Moreover,the texture strength and kernel average misorientation value are the highest,with values of 27.77 and 0.71,respectively.The increase in extrusion temperature leads to a gradual decrease in texture strength and kernel average misorientation value.The strength of the alloy is the highest at an extrusion temperature of 330℃.Its tensile yield stress is 254.7 MPa and ultimate tensile strength is 302.7 MPa,respectively.As the extrusion temperature increases,the strength of the alloy gradually decreases.At an extrusion temperature of 450℃,the tensile yield stress is 181.3 MPa and ultimate tensile strength is 265.7 MPa,respectively.The elongation first increases and then decreases,with an elongation of 20.9%at an extrusion temperature of 330℃.At an extrusion temperature of 430℃,the elongation reaches its maximum value,which is 23.6%.At an extrusion temperature of 450℃,the elongation reaches its lowest value,which is 16.4%.
文摘The influences of silicon addition to commercially pure magnesium(CP Mg)and cooling rate during solidification on the as-cast microstructure and shear mechanical properties of Mg-Si alloys were systematically investigated.For this purpose,the Mg-0.6Si,Mg-1.34Si,and Mg-3Si(wt%)alloys were considered as hypoeutectic,eutectic,and hypereutectic alloys,respectively.By decreasing the geometrical modulus of the solidifying section(increasing cooling rate),remarkable grain refinement,refining the dendrite arm spacing(DAS),and modification of Mg_(2)Si particles were achieved.Moreover,the grain size was refined via Si addition in the hypoeutectic range,while coarsening of grain size at high Si concentrations was observed.The results of shear punch testing and hardness measurements demonstrated that the ultimate shear strength(USS)and hardness increased by increasing the cooling rate during solidification.Moreover,Si addition generally improved hardness,while the highest USS level was achieved for the eutectic alloy due to the fine grain size and strengthening effect of the eutectic constituent.However,regarding the hypereutectic Mg-3Si alloy that exhibited high hardness,the shear properties were inferior due to the detrimental effect of the primary Mg_(2)Si particles.Finally,the results were discussed with consideration of the relationship between strength and hardness,for which the critical effect of Si was clarified.
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supported by the Key R&D Projects in Heilongjiang Province(GA23A901)。
文摘Al-Si-Cu-Mg alloy demonstrates a significant age-hardening effect,with its mechanical properties tunable by optimizing the aging parameters.To enhance this effect,the as-cast Al-8.5Si-2Cu-0.9Mg alloy was subjected to either single-stage aging at temperatures of 150℃,175℃,200℃,and 225℃for 0.5 h to 20 h;or double-stage aging:involving a first-stage aging treatment at 120℃for 1 h,3 h,5 h,or 7 h,followed by a second-stage aging treatment at 175℃ for 0.5 h to 20 h.The microstructure and mechanical properties were evaluated for samples aged at 175℃/7 h,175℃/10 h,120℃/5 h+175℃/5 h,and 120℃/5 h+175℃/8 h.XRD analysis reveals that the as-cast Al-8.5Si-2Cu-0.9Mg alloy consists of theα-Al,Si,θ-Al_(2)Cu,and Q-Al_(5)Cu_(2)Mg_8Si_6phases.The aging kinetics exhibit a double-peak behavior in both single-stage and double-stage aging processes.Under single-stage aging at 175℃/x h and double-stage aging(120℃/5 h+175℃/x h),the precipitates'size at the first peak is smaller than that at the second peak.Compared with single-stage aging(175℃/7 h),double-stage aging(120℃/5 h+175℃/5 h)produces a finer precipitate in the alloy.Theoretical calculations indicate that the number density and nucleation rate of both the Al_(5)Cu_(2)Mg_8Si_6 and Al_(2)Cu phases are higher during the double-stage aging(120℃/5 h+175℃/5 h)than those during the single-stage aging(175℃/7 h).Additionally,tensile tests at both room temperature and 250℃demonstrate that double-stage aging(120℃/5 h+175℃/5 h)significantly improves the mechanical properties of the alloy compared to single-stage aging(175℃/7 h),suggesting that double-stage aging is more effective for enhancing mechanical properties for this alloy.
基金supported by the National Natural Science Foundation of China(Grant Nos.51805084 and 52474401)Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2023B1515120086 and 2025A1515012873).
文摘The influence of oscillation amplitude on molten pool thermal history,weld morphology characteristics,microstructural evolution,and mechanical properties during laser oscillating welding of QP980 steel was systematically investigated.Results show that laser beam oscillation significantly regulates molten pool thermomechanical behavior through optimized spatial energy distribution,thereby enabling microstructural reconstruction and joint performance enhancement.As the oscillation amplitude increases from 0 to 0.8 mm,the molten pool duration extends to 1.7 times the original value,while peak temperature and average cooling rate decrease by 19%and 39%,respectively.This thermal regulation promotes weld surface width expansion from 0.72 to 1.07 mm.The welding mode undergoes a progressive transition from keyhole mode→transitional mode→conduction mode.This transformation effectively suppresses porosity defects,substantially reducing porosity from 1.8%to 0.15%.Microstructural analysis indicates that oscillation modifies the maximum temperature gradient direction within the molten pool,facilitating preferential growth of coarse columnar grains along the welding centerline to establish load-transfer-favorable crystallographic orientations.The synergistic effects of these factors substantially improve joint mechanical properties:lap joint shear load increases by 81.5%(7.6→13.8 kN),and fracture elongation is enhanced by 135%(0.98→2.3 mm).The operational principles of laser oscillation parameters on the welding quality of QP980 steel were elucidated,providing theoretical foundations for joining process optimization.
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 the National Natural Science Foundation of China(Nos.12072010 and 11674019)the Fundamental Research Funds for the Central Universities(No.YWF22-K-101)the National Key Research and Development Program of China(No.2022YFB3804300).
文摘Osteoarthritis(OA),the most common chronic joint disease,leads to remarkable morbidity and disability.The development of preclinical models that accurately recapitulate the bio-chemo-mechanical microenvironment of osteoarthritic joints is crucial for elucidating OA pathogenesis and facilitating drug development.In this study,we present a microfluidics-based cartilage-on-a-chip model that integrates tunable mechanical stimulation and inter-tissue/cell communication,mimicking the key physiological characteristics of articular cartilage for organ-level OA research.By applying controllable mechanical compression,we established a model that captures healthy and injury hallmarks of the cartilage and directly observed the mechanotransduction responses in chondrocytes.We further demonstrated that mechanically damaged cartilage induces synovial abnormalities and immune dysregulation and explored the potential of our chip as a platform for screening therapeutic targets.This cartilage-on-a-chip offers an in vitro system with a close-to-in vivo microenvironment for investigating complex bio-chemo-mechanical interactions,paving the way for advanced studies on OA pathogenesis and drug screening.
基金supported by the Special Project of Gansu Province,China(Nos.23ZDGA010,22ZD6GA008)the Central Guiding Fund for Local Science and Technology Development Project,China(Nos.24ZYQA054,23ZYQA308)the Key Project of Research and Innovation in Universities,China(No.2024CXPT-06)。
文摘Inconel 625 alloy components were fabricated using hot wire laser metal deposition(HW-LMD)through process optimization,achieving a wire deposition rate of 1.72 kg/h.The microstructure and mechanical properties of the HW-LMD Inconel 625 alloys were systematically investigated.The results revealed that the microstructure of the HWLMD Inconel 625 alloys consisted of columnar dendrites,characterized by an average grain size of 12.5μm and a strong{100}〈001〉texture.The main phase identified wasγ-Ni,with the precipitation of Laves phase,measuring less than 1μm,observed in the inter-columnar dendritic regions.The average microhardness of the HW-LMD Inconel 625 alloys was HV1.0258.The yield strength and ultimate tensile strength were 493.5 and 837.4 MPa,respectively,with elongation exceeding 50%.Impact absorbing energies at 25 and-78℃were 223.08 and 200.24 J,respectively.Both the tensile and impact fracture surfaces exhibited dimples,indicating a ductile fracture mechanism during the deformation process.
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Funded by the National Natural Science Foundation of China(Nos.52404378 and 52371019)the Basic Scientific Research Project of Liaoning Provincial Education Department(No.JYTQN2023009)the Dalian Science&Technology Innovation Foundation Project(No.2024JJ11PT003)。
文摘W-CoFeNi WHAs(tungsten heavy alloys)were fabricated by powder metallurgy with sintering temperatures ranging from 1480 to 1560℃.The influence of sintering temperatures on microstructure evolutions and mechanical properties of W-CoFeNi WHAs was investigated.The experimental results show that near-spherical W grains are distributed in CoFeNi ternary multi-principal-elements alloy(MPEA)with the formation of W-richμphase in all W-CoFeNi WHAs.The volume fractions ofμphase and average W grain size increase with sintering temperatures changing from 1480 to 1560℃.The activation energy for W grain growth is significantly higher than that of traditional W-Ni-Fe and W-Ni-Co WHAs,which indicates grain coarsening behavior in CoFeNi MPEA became more difficult compared to the conventional binder alloys.W-CoFeNi sintered at 1480℃exhibits the highest yield strength of 698 MPa among all WHAs due to finer W grain size.The compressive strength and fracture strain of W-CoFeNi reduce when sintering temperatures rise from 1480 to 1560℃.
基金financially supported by the National Natural Science Foundation of China(Nos.52034005,52227807,52104383,and 52222410)the Shaanxi Province National Science Fund for Distinguished Young Scholars,China(No.2022JC-24)+1 种基金the Key Research and Development Program of Shaanxi Province,China(No.2022JBGS2-01)the Central Guidance on Local Science and TechnologyDevelopment Fund of Shaanxi Province,China(No.2024ZY-JCYJ-04-09).
文摘Twinning-induced plasticity(TWIP)steel was processed using electrically assisted friction stir welding(EFSW).The microstructure,mechanical properties,and deformation behavior of the welded joints were systematically investigated.The results show that the average grain size was refined from 3.67μm in the base material(BM)to 1.39μm in the stir zone(SZ),while it increased to 4.19μm in the heat-affected zone(HAZ).The fraction of twin boundaries(TBs)decreased from 20.7%in the BM to 6.9%in the SZ and increased to24.5%in the HAZ.The ultimate tensile strength,yield strength,and elongation of the BM were 1021 MPa,505 MPa,and 65.8%,respectively.In comparison,the EFSW joint exhibited values of 1055 MPa,561 MPa,and 60.8%,corresponding to 103.3%,111.1%,and 92.4%of those of the BM,respectively.During tensile testing,plastic deformation was primarily concentrated in the BM,although both the SZ and HAZ also exhibited notable plastic deformation.Fracture ultimately occurred in the BM.
