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Journal of Central South University 2022年第6期29卷 1799-1810页

作者： YANG Bao-zhen XIONG Xiang LIU Ru-tie CHEN Jie State Key Laboratory of powder metallurgy Central South UniversityChangsha 410083China

In this study,non-equiatomic Fe_(70)Co_(7.5)Cr_(7.5)Ni_(7.5)V_(7.5) medium-entropy alloys(MEAs)with different carbon contents were prepared via mechanical ball-milling,cold pressing and vacuum *** microstructural evolution,mechanical properties and wear resistance of the MEAs were ***_(70)Co_(7.5)Cr_(7.5)Ni_(7.5)V_(7.5) exhibited a bodycentered cubic(bcc)structure withσphase *** adding 4 at%and 8 at%carbon,the phase composition of the alloys was transformed to bcc+MC+σand bcc+MC+M_(23)C_(6),*** mechanical properties and wear resistance were observed to be significantly enhanced by the formation of *** the carbon content,the corresponding bending strength and hardness increased from 1520 to 3245 MPa and HRC 57.2 to HRC 61.4,***,the dominant wear mechanism changed from the adhesion wear to the abrasion *** to the evenly distributed carbides and precipitated nanocarbides,Fe_(64.4)Co_(6.9)Cr_(6.9)Ni_(6.9)V_(6.9)C_(8) revealed an extremely low specific wear rate of 1.3×10^(−6) mm_(2)/(N·m)under a load of 10 N.

关键词： medium-entropy alloys powder metallurgy carbide wear resistance

Effect of milling time on microstructure of Ti35Nb2.5Sn/10HA biocomposite fabricated by powder metallurgy and sintering

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Transactions of Nonferrous Metals Society of China 2012年第3期22卷 608-612页

作者：王晓鹏徐丽娟陈玉勇禹基道肖树龙孔凡涛刘志光哈尔滨工业大学材料科学与工程学院哈尔滨150001 哈尔滨工业大学金属精密热加工国家重点实验室哈尔滨150001 全北国立大学先进材料工程研究部

A new β-Ti based Ti35Nb2.5Sn/10 hydroxyapitite（HA） biocompatible composite was fabricated by mechanical milling and pulsed current activated sintering（PCAS）.The microstructures of Ti35Nb2.5Sn/10HA powder particles and composites sintered from the milled powders were *** indicated that α-Ti phase began to transform into β-Ti phase after the powders were mechanically milled for 8 *** mechanical milling for 12 h,α-Ti completely transformed into β-Ti phase,and the ultra fine Ti35Nb2.5Sn/10HA composite powders were *** ultra fine grain sized Ti35Nb2.5Sn/10HA sintered composites were obtained by *** hardness and relative density of the sintered composites both increased with increasing the ball milling time.

关键词： Ti35Nb2.5Sn/10HA ultrafine grain powder metallurgy milling time

Structure of Grading a Resistor-Heated System of Warm Compaction in powder metallurgy

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International Journal of Plant Engineering and Management 2005年第2期10卷 108-112页

作者： LIUHua SHAOMing CHENWei-ping ZHUQuan-li LIYuan-yuan CollegeofMechanicalEngineering SouthChinaUniversityofTechnologyGuangzhou510640P.R.China CollegeofMechanicalEngineering SouthChinaUniversityofTechnologyGuangzhou510640P.R.China／／GuangdongStandardizationInstitutionGuangzhou510220P.R.China

We present the scheme of the structure of grading a resistor-heated system ofwarm compaction in powder metallurgy. The structure has the first heater and the second heater thatare heated by electrical tubes. powder is heated in turn in the first heater and the second heater,where there is the mass fluidity of powder under gravity. The dimensions of the first heater andthe second heater were calculated from the Fourier equation of heat conduction, and the boundarycondition was constant temperature. The drawings of the first heater, the second heater and thepowder-delivering device were given. The structure of the heat equipment is simple and easy tomanufacture. Finally, an exact warm compaction press system HGWY- II was developed for the heatingsystem.

关键词： resistor heating grading heating warm compaction powder metallurgy

Achieving superior performance in powder-metallurgy near-βtitanium alloy by combining hot rolling and rapid heat treatment followed by aging

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Journal of Materials Science & Technology 2024年第4期171卷 24-36页

作者： Fucheng Qiu Tuo Cheng Yuchao Song Orest M.Ivasishin Dmytro G.Savvakin Guangyu Ma Huiyan Xu College of Materials Science and Engineering Jilin UniversityChangchun 130025China International Center of Future Science Jilin UniversityChangchun 130025China G.V.Kurdyumov Institute for Metal Physics KyivUkraine College of Biological and Agricultural Jilin UniversityChangchun 130025China

Heat treatment plays an important role in tailoring the mechanical properties of powder-metallurgy(PM)titanium ***,only limited work about the rapid heat treatment(RHT)of PM titanium alloys has been *** this work,RHT was applied to PM Ti-5Al-5Mo-5V-1Cr-1Fe alloy after hot rolling to study the evolution of its mechanical properties and the influence of residual pores on its *** hot rolling and annealing,a fine and uniformα+βstructure with few residual pores is *** RHT,the primaryαdissolves gradually and completes in theβregion,and theβgrains then grow,resulting in the continuous decrease in elongation after ***,the tensile strength first increases and then decreases with increasing RHT temperature,owing to the increase in volume fraction of secondaryαinα+βregion and theβgrain growth inβ*** contrast to the RHT of cast-and-wrought titanium,the negative influence of residual pores lowers the RHT temperature for obtaining the highest tensile strength to a temperature below theβ-transus *** the negative influence of the residual pores,retained primaryαand fineβgrains with fine secondaryαinside contribute to achieving a good strength/ductility balance(1570 MPa and 6.1%,respectively).Addi-tionally,although at higher cycles to failure,the negative influence of residual pores increases as it affects the crack initiation zone at the subsurface,the good resistance of secondaryαto fatigue crack propaga-tion still enhances the fatigue strength considerably(about 300 MPa).This work suggests a cost-effective strategy to produce titanium alloys with high performance.

关键词： Rapid heat treatment powder metallurgy Mechanical properties Near-βtitanium Residual pores

Study on the Agile Manufacturing of the powder metallurgy Enterprise Cluster

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Study on the Agile Manufacturing of the Powder Metallurgy En...

Effect of Die Wall Lubrication on Warm Compaction powder metallurgy

第七届国际粉体检测与控制学术会议

作者： Li Guofu Ge Huansen Qiu Qing Faculty of Engineering,Ningbo University,China Ningbo University56#,Zhejiang 315211,China

Agile manufacturing,aimed at responding to the market demands quickly and providing products required to customers expeditiously,has many advantages to reduce the stocks and the costs of the powder metallurgy enterprises,In addition,it can improve the market competitive ability of the *** on the analysis of the requirements and foundations of agile manufacturing in powder metallurgy enterprise cluster,we realize this agile manufacturing and im- prove the degree of product customization,by integrating and sharing manufacturing resources information in powder met- allurgy enterprise cluster,and by making full use of the superiority of the manufacturing resources of the *** the same time,this paper also suggests the agile manufacturing mode fit for the existing

关键词： powder metallurgy Enterprise cluster Manufacturing resources Agile manufacturing

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Effect of Die Wall Lubrication on Warm Compaction Powder Met...

Workability Studies in Forming of Sintered Fe-0.35Cpowder metallurgy Preform During Cold Upsetting

第十届国际制造工程与管理会议

作者： LI Yuan-yuan NGAI Tungwai Leo ZHANG Da-tong LONG Yan XIA Wei(College of Mechanical Engineering South China University ofTechnology Guangzhou 510640 China)

＜正＞Die wall lubrication was applied on warm compaction powder metallurgy in hope to reduce the concentration level of the admixed lubricant since lubricant is harmful to the mechanical property of the sintered materials. Iron-based samples were prepared by die wall lubricated warm compaction at 135 ℃and 175 ℃, using polytetrafluoroethylene （PTFE） emulsion as die wall lubricant. A compacting pressure of 700 MPa and 550 MPa were used. The admixed lubricant concentration ranging from 0 to 0. 6 wt. % was used in this study. Compared with non-die wall lubricated samples, the die wall lubricated samples have higher green densities. Results show that in addition to the decrease in ejection forces, green density of the compacts increased linearly with the decrease in admixed lubricant content. Mechanical property of the sintered compacts increase sharply when the admixed lubricant concentration reduced to 0.125 wt. % or less. Ejection force data indicated that samples with die wall lubrication show lower ejection forces when compared with samples without die wall lubrication. No scoring was observed in all experiments even for samples contain no admixed lubricant. Our results indicated that under experimental condition used in this study, no matter at which compaction pressure, compaction temperature, graphite and lubricant contents in the powder the die wall lubricated warm compaction would give the highest green density and lowest ejection force. It can be concluded that combination of die wall lubrication and warm compaction can provide P/M products with higher density and better quality. It is a feasible way to produce high performance P/M parts if suitable die wall lubrication system was applied.

关键词： warm compaction die wall lubrication powder metallurgy

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Journal of Iron and Steel Research International 2011年第12期18卷 71-78页

作者： S Narayan A Rajeshkannan School of Engineering and Physics Faculty of ScienceTechnology and EnvironmentUniversity of the South Pacific(Laucala Campus)

An experimental investigation on the workability behaviour of sintered Fe-0.35C steel preforms under cold upsetting,have been studied in order to understand the influence of aspect ratio and lubrication condition on the workability *** above mentioned powder metallurgy sintered preform with constant initial theoretical density of 84% of different aspect ratios,namely,0.4 and 0.6 respectively were prepared using a suitable die-set assembly on a 1 MN capacity hydraulic press and sintered for 90 min at 1200 ℃.Each sintered preform was cold upset under nil/no and graphite frictional constraint,*** the condition of triaxial stress densification state,axial stress,hoop stress,hydrostatic stress,effective stress and formability stress index against axial strain relationship was established and presented in this *** more,attained density was considered to establish formability stress index and various stress ratio parameters behaviour.

关键词： powder metallurgy failure analysis plastic behaviour workability

Progress in processing of porous titanium:a review

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Rare Metals 2024年第5期43卷 1932-1955页

作者： Xiao-Li Yang Xian-Feng Du Zhi-Lin Xu Zhong-Shuai Liang Li-Long Xiong Engineering Research Center of Energy Storage Materials and Devices Ministry of EducationSchool of ChemistryXi'an Jiaotong UniversityXi'an 710049China

As a novel structural and functional material,porous titanium and its alloys have been widely used in the aerospace,marine engineering and biomedical fields due to their high corrosion resistance,low density,good biocompatibility and excellent mechanical ***,in this paper,a comprehensive review of powder metallurgy(PM)(including additive manufacturing(AM)processes)for fabricating porous titanium is firstly covered in terms of their working principles,capabilities,shortcomings and ***,the influencing factors of various methods on final pore structure of porous Ti are ***,a summary of the chemical methods(CM)to obtain the porous Ti is also provided,such as dealloying method and reduction ***,the tendency and direction of preparation technology as well as application of porous titanium were prospected.

关键词： Porous titanium powder metallurgy Chemical method Pore structure Processing process

Rapid in-situ reaction synthesis of novel TiC and carbon nanotubes reinforced titanium matrix composites

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Journal of Materials Science & Technology 2017年第10期33卷 1165-1171页

作者： Xianglong Sun Yuanfei Han Sanchen Cao Peikun Qiu Weijie Lu State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University Shanghai 200240 China

In-situ TiC and remained multi-walled carbon nanotubes（MWCNTs） reinforced Ti composites were synthesized using vacuum hot-press sintering and hot rolling. The effect of weight fraction of MWCNTs on microstructural evolution and mechanical properties of the Ti composites was investigated. The results indicated that both proportion and particle size of TiC increased in proportion to MWCNTs content, which resulted in different matrix microstructure, and the grains were obviously refined after rolling deformation. The hardness tests indicated that MWCNTs addition could make the composites harden, and 18.4%improvement in hardness was obtained after hot rolling. The significant improvement in both strength and hardness could be attributed to grain refinement, solid solution strengthening of carbon and dispersion strengthening of TiC particles and remained MWCNTs. A good combination of strength and ductility were achieved in Ti–1 wt% MWCNTs composites, which were in accordance with the uniform distribution of smaller-sized TiC particles in Ti matrix.

关键词： Titanium matrix composites CNTs powder metallurgy Hot-rolling

Two-stage aging treatment to accelerate aging kinetics without impairing strength in B_4C/7A04Al composite

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Science China(Technological Sciences) 2024年第8期67卷 2485-2492页

作者： CHEN YunTao MA GuoNan ZHU ShiZe WANG Dong XIAO BoLv MA ZongYi Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Centre of Excellence for Advanced Materials Dongguan 523808China

Aging treatments are the key process to obtain satisfactory strength for 7xxxAl alloys and their composites. However, traditional single-stage(SS) aging is time-consuming to reach a peak strength condition. In this study, an efficient 120℃ + 160℃ two-stage(TS) aging treatment was proposed on a B_4C/7A04Al composite fabricated via powder metallurgy(PM) technology, which could acquire similar peak-aging strength but only took about 15% of the time compared to traditional 120℃ SS aging. The evolution of precipitation during the TS aging was investigated, as well as those of the 7A04Al alloys for comparison. In the second stage aging process, the higher aging temperature accelerated the nucleation of η′ phases inside the grains and thus increased the density of precipitates. Moreover, the short aging time limited the coarsening of precipitates and the broadening of precipitatefree zones. The above factors were beneficial for quickly obtaining satisfactory precipitation strengthening effects. The B_4C/7A04Al composite exhibited slower aging kinetics than the 7A04Al alloy in the TS aging. Mg elements consumption by the chemical reaction between B impurities introduced by B_4C particles and the Al matrix was considered to potentially retard the aging kinetics of the B_4C/7A04Al composite. Nevertheless, the precipitation sequence was not affected.

关键词： aluminum matrix composites aging treatment powder metallurgy mechanical properties precipitation