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Laser powder bed fusion of biodegradable Zn-4 Cu alloy:Processing,microstructure and properties
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作者 WANG Han-dan ZHAO Yang +3 位作者 DONG An-ping HE Lin SHUAI Ci-jun GAO Cheng-de 《Journal of Central South University》 2026年第1期66-77,共12页
Zn's natural degradability and biocompatibility make it a promising candidate for implants,however,its mechanical properties remain insufficient for bone applications.In this study,the performance of Zn was enhanc... Zn's natural degradability and biocompatibility make it a promising candidate for implants,however,its mechanical properties remain insufficient for bone applications.In this study,the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion(LPBF).Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed.Under optimized conditions of 100 W and 100 mm/s,high density(99.58%)Zn-Cu alloys with improved hardness(68.2 HV)and yield strength(160 MPa)were achieved.These improvements are attributed to solid solution strengthening,segregation strengthening,and grain refinement.The Zn-Cu alloys also demonstrated favorable degradation behavior,with a rate of 0.16 mm/year.This degradation is primarily driven by micro-galvanic corrosion between the CuZn 5 phase and Zn matrix,along with refined grains and increased grain boundary density.This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF. 展开更多
关键词 laser powder bed fusion(LPBF) Zn-Cu alloys microstructure mechanical properties BIODEGRADATION
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Microstructures and mechanical properties of friction stir welded and processed high entropy alloys
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作者 Kang Chen Jian Miao +2 位作者 Huijie Zhang Qi Cheng Yingling Wang 《Defence Technology(防务技术)》 2026年第1期80-108,共29页
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
关键词 High entropy alloys Friction stir welding/processing microstructure Mechanical property
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Microstructure and wear property of laser cladded WC particles reinforced CoCrFeNiMo composite coatings on Cr 12 MoV steel 被引量:2
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作者 LIU Xing-yi YANG Xiao +6 位作者 CHEN Zu-bin GUO Chun-huan LI Hai-xin YANG Zhen-lin DONG Tao JIANG Feng-chun QIAO Zhu-hui 《Journal of Central South University》 2025年第1期49-70,共22页
WC particles reinforced CoCrFeNiMo high-entropy alloy(HEA)composite coatings were prepared on Cr12MoV steel successfully by laser cladding technology to improve the wear resistance of substrates.Effect of WC content o... WC particles reinforced CoCrFeNiMo high-entropy alloy(HEA)composite coatings were prepared on Cr12MoV steel successfully by laser cladding technology to improve the wear resistance of substrates.Effect of WC content on microstructure and wear property of the composite coatings was studied in detail.Large numbers of carbides with four main types:primary carbide crystals,eutectic structures,massive crystals growing along the periphery of the remaining WC particles and incompletely fused WC particles,were found to exist in the WC/CoCrFeNiMo composite coatings.With increasing WC content,the microhardness of coatings is gradually improved while the average friction coefficients follow the opposite trend due to solid solution strengthening and second phase strengthening effect.The maximum microhardness and minimum friction coefficient are HV_(0.2)689.7 and 0.72,respectively,for the composite coating with 30 wt.%WC,the wear resistance of the substrate is improved significantly,the wear mechanisms are spalling wear and abrasive wear due to their high microhardness. 展开更多
关键词 laser cladding CoCrFeNiMo coating WC particles microstructure wear resistance
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Improved microstructure and mechanical properties of A517Q steel fabricated via laser directed energy deposition assisted by ultrasonic vibration combined with tempering treatment 被引量:1
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作者 LI Jian-liang REN He +6 位作者 WANG Qi-chen CHEN Zu-bin JIANG Guo-rui SUN Wen-yao SU Ye-tong GUO Chun-huan JIANG Feng-chun 《Journal of Central South University》 2025年第3期760-775,共16页
In this work,ultrasonic energy field assistance combined with tempering treatment is proposed to improve the microstructure and mechanical properties of A517Q alloy steel fabricated by laser directed energy deposition... In this work,ultrasonic energy field assistance combined with tempering treatment is proposed to improve the microstructure and mechanical properties of A517Q alloy steel fabricated by laser directed energy deposition(LDED).The effects of ultrasonic vibration(UV)and tempering treatment on microstructure evolution,microhardness distribution and mechanical properties of deposition layer were studied in detail.The microstructure of UV assisted LDED sample after tempering is mainly composed of tempered sorbite(TS).Due to the improvement of microstructure inhomogeneity and grains refinement,UV assisted LDED sample with tempering treatment obtains excellent mechanical properties.The ultimate tensile strength(UTS),yield strength(YS)and elongation after breaking(EL)reach 765 MPa,657 MPa and 19.5%,the increase ratios of UTS and YS are 14.5%and 33.8%while maintaining plasticity compared to original LDED sample,respectively.It is obvious that ultrasonic vibration combined with tempering is a potential and effective method to obtain uniform microstructure and excellent mechanical properties in metal laser directed energy deposition field. 展开更多
关键词 laser directed energy deposition ultrasonic vibration TEMPERING microstructure mechanical property A517Q steel
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Progress in the Application of Cellular Automata to the Evolution of Solidified Microstructure
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作者 WEI Pengfei CHEN Yunbo +5 位作者 WEI Shizhong MAO Feng WANG Xiaodong CHEN Chong WANG Jinnan WANG Zidong 《材料导报》 北大核心 2025年第12期196-213,共18页
The performance of a material is directly affected by its microstructural development during the solidification phase. Discrete cellular automaton (CA) models are widelyused in materials science to simulate and predic... The performance of a material is directly affected by its microstructural development during the solidification phase. Discrete cellular automaton (CA) models are widelyused in materials science to simulate and predict microstructural growth. This review comprehensively explains the developments and applications of CA in solidification structure simulation, including the theoretical underpinnings, computational procedures, software development, and recent advances. Summarizes the potential and limitations of cellular automata in understanding microstructure evolution during solidification, explores the evolution of microstructures during solidification, and adds to our existing knowledge of cellular automaton theory. Finally, the research trend in simulating the evolution of the solidification microstructure using cellular automaton theory is explored. 展开更多
关键词 cellular automata dendritic growth SIMULATION microstructure evolution SOLIDIFICATION
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Microstructure modulation strategies from pitch molecules to derived carbon materials for electrochemical energy storage
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作者 MENG Chao ZHANG Yan +4 位作者 WANG Ning ZHENG Xue-qing KONG De-yu HU Han WU Ming-bo 《新型炭材料(中英文)》 北大核心 2025年第4期837-859,共23页
Pitch is a complex mixture of polycyclic aromatic hydrocarbons and their non-metal derivatives that has a high carbon content.Using pitch as a precursor for carbon materials in alkali metal ion(Li^(+)/Na^(+)/K^(+))bat... Pitch is a complex mixture of polycyclic aromatic hydrocarbons and their non-metal derivatives that has a high carbon content.Using pitch as a precursor for carbon materials in alkali metal ion(Li^(+)/Na^(+)/K^(+))batteries has become of great interest.However,its direct pyrolysis often leads to microstructures with a high orientation and small interlayer spacing due to uncontrolled liquid-phase carbonization,resulting in subpar electrochemical performance.It is therefore important to control the microstructures of pitch-derived carbon materials in order to improve their electrochemical properties.We evaluate the latest progress in the development of these materials using various microstructural engineering approaches,highlighting their use in metal-ion batteries and supercapacitors.The advantages and limitations of pitch molecules and their carbon derivatives are outlined,together with strategies for their modification in order to improve their properties for specific applications.Future research possibilities for structure optimization,scalable production,and waste pitch recycling are also considered. 展开更多
关键词 Pitch precursor Carbon materials microstructure Modification strategies Electrochemical energy storage
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Effect of tantalum doping on the microstructure and photoelectrical properties of transparent conductive zinc oxide films
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作者 Kai Yi Hongxu Jiang +3 位作者 Yanbo Cai Guangwei Wang Fei Liu Deliang Wang 《中国科学技术大学学报》 北大核心 2025年第4期49-57,48,I0002,共11页
ZnO thin films with varying Ta concentrations were fabricated through magnetron sputtering.The crystallinity and surface morphology of the ZnO films are significantly influenced by the incorporation of Ta,as evidenced... ZnO thin films with varying Ta concentrations were fabricated through magnetron sputtering.The crystallinity and surface morphology of the ZnO films are significantly influenced by the incorporation of Ta,as evidenced by the X-ray diffraction and scanning electron microscopy results.The lattice constants,as determined by X-ray diffraction,contradict the disparity in Ta and Zn ion radii,which is attributed to the impact of interstitial defects.This inconsistency introduces variations in carrier concentration in this experiment compared with prior studies.Subsequent exploration of the luminescent characteristics and emission mechanism of defect levels in Ta-doped ZnO films was conducted through photoluminescence.Furthermore,the factors influencing the bandgap are discussed. 展开更多
关键词 tantalum-doped zinc oxide RF magnetron sputtering microstructure PHOTOLUMINESCENCE
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Effects of Er on microstructure and corrosion resistance of degradable Mg-Al-Zn-Mn magnesium alloy
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作者 MA Wei MA Zheng-qing CHEN Bai-hua 《Journal of Central South University》 2025年第7期2404-2415,共12页
Magnesium alloys as medical implant materials necessitate a lower and adjustable corrosion rate for clinical applications.The microstructure and corrosion behavior of AZ31Mn-xEr(x=0.1,0.5,1.2)alloys were systematicall... Magnesium alloys as medical implant materials necessitate a lower and adjustable corrosion rate for clinical applications.The microstructure and corrosion behavior of AZ31Mn-xEr(x=0.1,0.5,1.2)alloys were systematically investigated using optical microscopy(OM),scanning electron microscopy(SEM),and X-ray photoelectron spectroscopy(XPS),combined with Tafel polarization and electrochemical impedance spectroscopy(EIS)analyses.The findings showed that the alloying element Er refined the grain structure during solidification by increasing the nucleation rate and forming a secondary phase of Al_(3)Er with Al.The Er and Mg in the matrix co-oxidize to form a dense MgO/Er_(2)O_(3)composite oxide,preventing the formation of loose magnesium hydroxide/basic magnesium carbonate.The trace alloying element Mn interacts with impurities Fe in the magnesium matrix to form an AlFeMn second phase,reducing micro-galvanic corrosion driving force.Electrochemical testing in a 3.5%NaCl solution demonstrated a marked reduction in corrosion rate from 10.46 mm/a(AZ 31 Mn alloy)to 0.44 mm/a(AZ31Mn-1.2Er alloy).This research offers a reference for searching for corrosion-resistant magnesium alloy and degradable medical magnesium alloy materials. 展开更多
关键词 magnesium alloy corrosion microstructure Tafel curve AC impedance X-ray photoelectron spectroscopy
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Microstructure and mechanical properties of welds of AZ31B magnesium alloy produced by different gas tungsten arc welding variants
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作者 S.Srinivasan R.Ravi Bharath +1 位作者 A.Atrens P.Bala Srinivasan 《Defence Technology(防务技术)》 2025年第2期98-110,共13页
This work aimed to(i)understand conventional and pulse gas tungsten arc welding(GTAW)of AZ31B,and(ii)explore high frequency welding(100 Hz-1500 Hz).GTA welding with alternating current(AC)and direct current electrode ... This work aimed to(i)understand conventional and pulse gas tungsten arc welding(GTAW)of AZ31B,and(ii)explore high frequency welding(100 Hz-1500 Hz).GTA welding with alternating current(AC)and direct current electrode positive(DCEP)polarities yielded crack-free partial penetration welds for6 mm thick AZ31B alloy sheet.Welding under direct current electrode negative(DCEN)polarity with identical parameters as that for AC and DCEP resulted in full penetration welds that had microcracks.Defect-free full-penetration welds could be accomplished with pulse GTA welding using DCEN polarity at a pulse frequency of 1 Hz with a pulse duration ratio of 1:1.The resultant DCEN P 1:1 weld metal had a microstructure finer than the conventional DCEN weld.Welds produced with pulse duration ratios of 1:2and 1:4 lacked penetration but had a much finer microstructures because of the lower heat input.The arc constriction by the high frequency pulsing in the Activ Arc■-High frequency(AA-HF)mode welding was responsible for deeper penetration.Welds produced under DCEN pulsing and AA-HF conditions had hardness higher than conventional DCEN,DCEP and AC GTA welds,attributed to the finer microstructure.AA-HF GTA welding produced defect free deeper penetration welds with good microstructural features/mechanical properties and also gave an advantage of 50%enhanced productivity when welded at1500 Hz. 展开更多
关键词 AZ31B alloy Pulse GTAW High frequency microstructure Mechanical properties PRODUCTIVITY
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Microstructure and mechanical properties of aged Mg-Gd-Y-Zr-Ag alloy sheets processed by different rolling routes
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作者 ZHU Yu-ting CHEN Han +5 位作者 CHEN Zhi-yong HAN Yu-xiang JIANG Shu-nong GAO Yong-hao WAN Ying-chun LIU Chu-ming 《Journal of Central South University》 2025年第8期2809-2822,共14页
Microstructure and mechanical properties of aged Mg-10Gd-2Y-0.4Zr-0.4Ag alloy sheets prepared by different rolling routes were investigated.The results showed that the cross rolling aged(CRA)sheet possesses larger gra... Microstructure and mechanical properties of aged Mg-10Gd-2Y-0.4Zr-0.4Ag alloy sheets prepared by different rolling routes were investigated.The results showed that the cross rolling aged(CRA)sheet possesses larger grain size than unidirectional rolling aged(URA)sheet due to the occurrence of dynamic recovery during rolling which reduces the dislocation density and delays dynamic recrystallization(DRX).The URA sheet has basal texture and RD favored texture while CRA sheet has multiple-peak texture.Both sheets precipitate β'phase and CRA sheet exhibits a stronger aging response.The CRA sheet has higher yield strength and tensile strength than URA sheet,with reduced yield strength anisotropy but increased tensile strength anisotropy.Taking into account different strengthening mechanisms,although the finer grain size of URA sheet enhances grain boundary strengthening,CRA sheet is more responsive to aging,leading to superior aging-precipitated phase strengthening and consequently higher yield strength. 展开更多
关键词 Mg-Gd-Y-Zr-Ag alloy rolling routes aging precipitation microstructure strengthening mechanism
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Microstructure and electrochemical behavior of Al-8Si-3Fe-xIn coating alloy in a low chlorine environment
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作者 SHEN Ying ZHANG Jing +4 位作者 KOLAWOLE Sharafadeen Kunle LIU Ya ZHU Xiang-ying CHEN Jun-xiu SU Xu-ping 《Journal of Central South University》 2025年第4期1252-1271,共20页
In the process of protecting ferrous materials,aluminum coating usually forms a dense oxide film on the surface of the iron-based alloy.However,the capacity of the sacrificial anode is rather insufficient.In order to ... In the process of protecting ferrous materials,aluminum coating usually forms a dense oxide film on the surface of the iron-based alloy.However,the capacity of the sacrificial anode is rather insufficient.In order to solve this problem,the microstructure and electrochemical corrosion properties of Al-8Si-3Fe-xIn alloy under low chlorine conditions were studied.The results show that indium(In)dissolves to form In^(3+)and In^(+)reverse plating on the surface of the bare substrate to form a passivation film defect.When the In content is high,the segregated In forms an activation point in the form of a cathode phase.In activatesτ_(6)phase to form a micro-couple,which improves the non-uniform corrosion.The In-containing corrosion products at the phase boundary hinder the diffusion of Cl−.With an increase of In content,the self-corrosion potential(Ecorr)of the alloy shifts negatively,and the self-corrosion current density(Jcorr)decreases from 6.477μA/cm^(2)to 1.352μA/cm^(2),and then increases gradually.However,when the In content is 0.1%,the Ecorr of the alloy changes from−0.824 V to−0.932 V,and the Jcorr decreases from 6.477μA/cm^(2)to 4.699μA/cm^(2),suggesting that the use of sacrificial anode will give the best effect. 展开更多
关键词 aluminum coating microstructure electrochemical corrosion properties sacrificial anode hot-dip galvanizing
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Microstructure and mechanical properties of additively manufactu
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作者 MA Pan YANG Hong +5 位作者 ZHANG Zhi-yu XIE Xiao-chang YANG Ping KONDA-GOKULDOSS Prashanth ZHANG Han JIA Yan-dong 《Journal of Central South University》 2025年第4期1167-1178,共12页
High-entropy alloy composites(HEACs)have attracted significant attention due to their exceptional mechanical properties and chemical stability.By adjusting the content of reinforcing particles in the high-entropy allo... High-entropy alloy composites(HEACs)have attracted significant attention due to their exceptional mechanical properties and chemical stability.By adjusting the content of reinforcing particles in the high-entropy alloy and by employing advanced additive manufacturing techniques,high-performance HEACs can be fabricated.However,there is still considerable room for improvement in their performance.In this study,CoCrFeMnNi HEA powders were used as the matrix,and NiCoFeAlTi high-entropy intermetallic powders were used as the high-entropy reinforcement(HER).CoCrFeMnNi/NiCoFeAlTi HEACs were fabricated using selective laser melting technology.The study results indicate that after aging,the microstructure of HEACs with HER exhibits Al-and Ti-rich nano-oxide precipitates with an orthorhombic CMCM type structure system.After aging at 873 K for 2 h,HEACs with HER achieved excellent overall mechanical properties,with an ultimate tensile strength of 731 MPa.This is attributed to the combined and synergistic effects of precipitation strengthening,dislocation strengthening,and the high lattice distortion caused by high intragranular defects,which provide a multi-scale strengthening and hardening mechanism for the plastic deformation of HEACs with HER.This study demonstrates that aging plays a crucial role in controlling the precipitate phases in complex multi-element alloys. 展开更多
关键词 additive manufacturing selective laser melting high-entropy alloy composite high-entropy intermetallic powders aging treatment microstructure mechanical properties
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Effect of pre-heat treatment and subsequent ECAP-CU on microstructure and corrosion behavior of 7075 Al alloy fasteners
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作者 ZHANG Jun-jie HE Tao +4 位作者 DU Xiang-yang ALEXER Vereschaka SONG Miao CHEN Xi-lin LI Jian 《Journal of Central South University》 2025年第7期2383-2403,共21页
It is of great significance to study the corrosion process of aluminum(Al)alloys fasteners in order to mitigate corrosion for their widespread applications.In this paper,a method for enhancing the corrosion resistance... It is of great significance to study the corrosion process of aluminum(Al)alloys fasteners in order to mitigate corrosion for their widespread applications.In this paper,a method for enhancing the corrosion resistance of Al alloy fasteners is proposed.7075 Al alloy parts with a fine-grained microstructure were prepared by pre-heat treatment(PHT),combined subsequent equal channel angular pressing(ECAP)and cold upsetting(CU).The corrosion behavior of the specimens was investigated by intergranular corrosion and electrochemical test.Microstructure investigations were carried out by field emission scanning electron microscopy,energy dispersive spectrometer and transmission electron microscopy.The relationship between microstructural evolution and corrosion resistance changes was also explored.The results show that both PHT and ECAP-CU significantly improved the corrosion resistance of the samples and modified the corrosion process.The open circuit potential,corrosion current density and corrosion rate of the alloy on electrochemical test were(-0.812±8.854)×10^(-5) V(vs.SCE),(6.379±0.025)×10^(-6) A/cm^(2) and 0.066 mm/year,respectively,and the intergranular corrosion depth was(557±8)μm.The main factor controlling the corrosion behavior was the microstructure evolution.After PHT,the disappearance of the dendritic structure and the dissolution of the nonequilibrium second phase eliminated the potential difference between the phases,reducing the free energy in the as cast state.When ECAP-CU was used after PHT,the grain refinement was accompanied by a high density of grain boundaries and dislocations,which led to the formation of a denser passivation film on the alloy surface,improving the corrosion resistance in an aggressive environment. 展开更多
关键词 aluminum alloy fasteners heat treatment equal channel angular pressing cold upsetting microstructure corrosion resistance
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Erratum to:Evolution of microstructure and mechanical properties in multi-layer 316 L-TiC composite fabricated by selective laser melting additive manufacturing
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作者 Sasan YAZDANI Suleyman TEKELI +2 位作者 Hossein RABIEIFAR Ufuk TAŞCI Elina AKBARZADEH 《Journal of Central South University》 2025年第2期691-691,共1页
Because of an unfortunate mistake during the production of this article,the Acknowledgements have been omitted.The Acknowledgements are added as follows:Sasan YAZDANI would like to thank the Scientific and Technologic... Because of an unfortunate mistake during the production of this article,the Acknowledgements have been omitted.The Acknowledgements are added as follows:Sasan YAZDANI would like to thank the Scientific and Technological Research Council of Turkey(TÜB˙ITAK)for receiving financial support for this work through the 2221 Fellowship Program for Visiting Scientists and Scientists on Sabbatical Leave(Grant ID:E 21514107-115.02-228864).Sasan YAZDANI also expresses his gratitude to Sahand University of Technology for granting him sabbatical leave to facilitate the completion of this research. 展开更多
关键词 additive manufacturing microstructure mechanical properties fellowship program multi layer L TIC composite selective laser melting
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Microstructure evolution and mechanical properties of 2195 Al-Li alloy with different heat-treatment states via friction stir additive manufacturing
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作者 GAO Yong-hui JIANG Tao +5 位作者 DAI Guo-qing LI Jun GUO Yan-hua SUN Zhong-gang LIU Chun-hui ZHAN Li-hua 《Journal of Central South University》 2025年第11期4159-4179,共21页
Friction stir additive manufacturing(FSAM)is an innovative additive manufacturing(AM)method.The various heat treatment conditions of aluminum-lithium alloys using this method have not been widely discussed.In this stu... Friction stir additive manufacturing(FSAM)is an innovative additive manufacturing(AM)method.The various heat treatment conditions of aluminum-lithium alloys using this method have not been widely discussed.In this study,the microstructure evolution and mechanical properties of FSAM 2195 aluminum-lithium alloy in different heat treatment conditions(T3 and T8)were investigated.The results demonstrated that the heat treatment state of 2195 Al-Li alloys was minimally influenced by FSAM as the FSAM temperature exceeded the solid solution temperature.After conducting a single-pass FSAM experiment,a notable grain refinement was observed in the nugget zone(NZ)region compared to the base material(BM).The average grain size of the 2195-T3 alloy decreased from 6.1 to 2.9µm,while the proportion of high-angle grain boundaries increased from 16.5%to 43.9%.Similarly,the average grain size of the 2195-T8 alloy decreased from 8.9 to 2.8µm,with an increase in high-angle grain boundary from 37.6%to 59.2%.The tensile strength of the 2195-T3 Al-Li alloy reached 466 and 478 MPa in the NZ of single-pass and lap experiments,respectively.In comparison,the tensile strength of the 2195-T8 Al-Li alloy in the NZ could reach 452 and 481 MPa in single-pass and lap experiments,respectively.These results demonstrate the significant improvements in microstructure and mechanical properties were achieved through the FSAM process. 展开更多
关键词 2195 Al-Li alloys friction stir additive manufacturing microstructure evolution MICROHARDNESS
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Improvement of microstructure and microhardness of AZ31 Mg alloy sheet by cross-forging-bending repeated deformation with sharply increasing temperature
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作者 LU Li-wei LIANG Xing-jie +6 位作者 LI Min-hao WEI Yu-hui XI Yu-ze MA Min JING Lei WANG Li-fei DONG Jun 《Journal of Central South University》 2025年第11期4210-4227,共18页
In this study,AZ31 Mg alloy sheets were processed by a severe plastic deformation(SPD)technique called forging-bending repeated deformation(FBRD).The effect on the microstructure and microhardness of AZ31 Mg alloy thr... In this study,AZ31 Mg alloy sheets were processed by a severe plastic deformation(SPD)technique called forging-bending repeated deformation(FBRD).The effect on the microstructure and microhardness of AZ31 Mg alloy through FBRD was investigated with increasing temperature treatment and a 90°cross route.The results reveal that the effective strain increases with the number of passes.The flow uniformity is effectively enhanced due to alterations in shear deformation direction.After four passes of deformation,the average grain size is refined by 79.3%compared to the initial specimen.The grain refinement mechanism predominantly originates from the synergistic effects of discontinuous dynamic recrystallization(DDRX),continuous dynamic recrystallization(CDRX),and twinning-induced recrystallization(TDRX).The formation of{1012}extension twins(ET)significantly contributes to coarse grain subdivision and plastic deformation coordinated.Furthermore,pyramidal<c+a>slip activation effectively enhances the plasticity of Mg alloys.By post four-pass processing,the alloy exhibits a microhardness of 81.9HV,primarily governed by fine grain strengthening and dislocation strengthening mechanisms. 展开更多
关键词 AZ31 Mg alloy sheet forging-bending repeated deformation microstructure MICROHARDNESS
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Microstructure and wear property of SiC_(P)/AlSi10Mg composites prepared by laser powder bed fusion
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作者 GONG Zi-yi YE Nan +4 位作者 WU Zi-chun MAO Jie TANG Jian-cheng ZHUO Hai-ou XU Cheng-ru 《Journal of Central South University》 2025年第11期4143-4158,共16页
Additive manufacturing(AM)of SiC_(P)/Al composites has shown significant potential for expanding the application of aluminum matrix composites(AMCs)due to their outstanding mechanical properties and wear performance.H... Additive manufacturing(AM)of SiC_(P)/Al composites has shown significant potential for expanding the application of aluminum matrix composites(AMCs)due to their outstanding mechanical properties and wear performance.However,conventional mechanically mixed powders for AM are limited due to the possible powder agglomeration and poor fluidity.In this study,the spherical SiC_(P)/AlSi10Mg composite powders prepared by spray granulation were employed to fabricate SiC_(P)-reinforced AlSi10Mg composites using laser powder bed fusion(LPBF).The impacts of laser power on microstructure evolution and wear properties of composites were systematically investigated.The results indicated that an in-situ reaction between the aluminum matrix and SiC_(P)during the LpBF process,resulted in the formation of particle-like and strip-like strengthening phase Al_(4)SiC_(4).By adjusting the laser power(from 270 W to 350 W)to change the ratio of SiC_(P)to Al_(4)SiC_(4),micro-defects could be effectively limited,and wear performance could be improved.Consequently,with an optimized ratio of SiC_(P)to Al_(4)SiC_(4),the composite exhibited a mixed strengthening mechanism caused by the SiC_(P)and Al_(4)SiC_(4)reinforcing phases.At a laser power of 310 W,the sample exhibited minimal porosity with a microhardness value reaching 265.38HV,while maintaining relatively low average friction coefficient and wear rate.In addition,compared with other studies,the hardness obtained was superior to that of the AlSi10Mg and other reported SiC_(P)/AlSi10Mg composites with similar volume fractions using the mixed powders. 展开更多
关键词 SiC_(P)/AlSi10Mg composite powder laser powder bed fusion microstructure wear property
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Effect of pre-rolling temperature on microstructures, tensile properties and fracture behaviors of Al-5.9Zn-1.9Mg alloy during thermomechanical treatment
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作者 CHENG Jun-hua GUO Xiao-fang +3 位作者 LIU Chang SHAO Hong-bang LIU Yu HUANG Yuan-chun 《Journal of Central South University》 2025年第9期3237-3254,共18页
The microstructures,mechanical properties,and fracture behaviors of an Al-5.9Zn-1.9Mg alloy subjected to thermomechanical treatment across different pre-rolling temperatures have been exhaustively investigated in pres... The microstructures,mechanical properties,and fracture behaviors of an Al-5.9Zn-1.9Mg alloy subjected to thermomechanical treatment across different pre-rolling temperatures have been exhaustively investigated in present work.The pre-deformation temperature exerts a modest influence on grain morphology,while it profoundly impacts the dislocation configurations and precipitation behaviors.Elevating the rolling temperature from ambient to 170℃results in a reduction in dislocation density within grains accompanied by a notable enhancement in their distributional uniformity.While advancing the temperature to 320℃prompts the premature formation of precipitates during deformation,which diminishes the precipitation during the subsequent ageing.Tensile results reveal that the thermomechanical treatment incorporating pre-rolling at 170℃confers a substantial strengthening effect on the alloy on the basis of both grain boundary strengthening and dislocation strengthening stemmed from pre-deformation along with the precipitation strengthening generated by ageing.Furthermore,the microstructure exhibits a relatively scarce presence of inhomogeneous features such as dislocation pile-ups and micro shear bands,contributing favorably to enhance the ductility of the alloy that presents the mixture of cleavage fracture and dimple-induced failure. 展开更多
关键词 Al-Zn-Mg alloy thermomechanical treatment deformation temperature microstructureS tensile properties
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Effect of sodium sulfate on strength and microstructure of alkali-activated fly ash based geopolymer 被引量:29
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作者 LV Qing-feng WANG Zi-shuai +2 位作者 GU Liu-yang CHEN Yi SHAN Xiao-kang 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第6期1691-1702,共12页
The main objective of this paper focuses on the changes that occur in the strength and microstructural properties of sodium silicate activated fly ash based geopolymer due to varying the sulfate salt and water content... The main objective of this paper focuses on the changes that occur in the strength and microstructural properties of sodium silicate activated fly ash based geopolymer due to varying the sulfate salt and water content.A series of tests including X-ray diffraction,Fourier transform infrared spectroscopy,scanning electron microscopy,physical adsorption and unconfined compressive strength were used to investigate this effect.The results indicate that the higher water content has an adverse effect on the alkali activation and microstructural properties of geopolymer,so the optimum mass ratio of sodium sulfate in alkali-activated geopolymer under different water-to-binder ratios shows a“peak shifting”phenomenon,i.e.,the higher the water-to-binder ratio,the higher the optimum mass ratio.Lower presence of sodium sulfate has no significant effect on the alkali-activated geopolymer systems;higher addition of sodium sulfate,however,could cause the symmetrical stretching vibration of Si—O and the symmetrical stretching vibration of Si—O—Si and Al—O—Si,and promote the formation of N-A-S-H gels.Furthermore,the cement effect of the gel and sodium sulfate aggregate could improve the integrity of pore structure obviously.The maximum strength of geopolymer curing at ambient temperature was 52 MPa.This study obtains the rule that the strength properties of alkali-activated geopolymers vary with the water-to-binder ratio and sodium sulfate content.The feasibility of geopolymer co-activated by sodium sulfate and sodium silicate was investigated,and reference for engineering application of alkali-activated geopolymer in salt-bearing areas was provided. 展开更多
关键词 GEOPOLYMER microstructure fly ash sodium sulfate water-to-binder ratio
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Effects of Electron Beam Local Postweld Heat Treatment on Microstructure and Properties of 30CrMnSiNi2A Steel Welded Joints 被引量:14
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作者 CHEN Fu-rong 1, HUO Li-xing 1, ZHANG Yu-feng 1, ZHANG Li 1, LIU Fang-jun 2, CHEN Gang 2 (1. College of Materials Science and Engineering, Tianjin University, Tianjin 300072, China 2. Aviation Techniques Institute of Beijing, Beijing 100024, China) 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期47-48,共2页
To improve the microstructure and properties of the electron beam welded joints, the vacuum or furnace whole post weld heat treatment (FWPWHT) usually should be done on it. The electron beam local post weld heat treat... To improve the microstructure and properties of the electron beam welded joints, the vacuum or furnace whole post weld heat treatment (FWPWHT) usually should be done on it. The electron beam local post weld heat treatment (EBLPWHT) is a rather new heat treatment procedure that provides the advantages of high precision, flexibility and efficiency, energy saving and higher productivity. In this paper, the microstructure, mechanical properties, fracture toughness and fatigue properties of electron beam welded joints of 30CrMnSiNi2A steel in as-welded (AW) and EBLPWHT conditions have been investigated respectively. The results show that the microstructures of different zones of joints in as-welded condition are changed by EBLPWHT procedure, in which the welds from coarse needle martensite into lath-shaped martensite; the main structures of heat affected zones (HAZ) from lath-shaped martensite into lower bainite. The properties of welded joints can be improved by the EBLPWHT in some extent, especially the fracture toughness of the welds and the fatigue crack resistance of welded joints can be sufficiently improved. However, more appropriate heat treatment parameters of the EBLPWHT have to be studied in order to increase the mechanical properties of base metal near by the HAZ. 展开更多
关键词 electron beam welding electron beam local heat treatment microstructure fracture toughness fatigue properties
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