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Acta Metallurgica Sinica(English Letters) 2022年第3期35卷 411-424页

作者： Rong Xu ruidi li Tiechui Yuan Hongbin Zhu Ping li State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083.China CRRC Industrial Academy Co. LtdBeijing 100070China

In order to refine the microstructure and improve the performance of direct energy deposited(DED)additively manufactured Al–Mg–Sc–Zr alloy,TiC-modified Al–Mg–Sc–Zr composites were prepared by DED and the effect of TiC content on the microstructure and performance was *** the absence of TiC particle,the microstructure of Al–Mg–Sc–Zr alloy prepared by DED consisted of fine grains with average size of 8.36μm,and well-dispersed nano-Al;(Sc,Zr)particles inside the grains and Mg;Si phase along the grain *** the addition of 1 wt%TiC,the microstructure of TiC/Al–Mg–Sc–Zr prepared by DED became finer apparently compared with that without TiC;while the further increase of TiC content to 3 wt%,the microstructure of TiC/Al–Mg–Sc–Zr prepared by DED became coarser with appearance of a new kind of needle-like(Ti,Zr);Si;***,the addition of TiC decreased the porosity of Al–Mg–Sc–Zr prepared by ***,after the addition of TiC,the tensile strength increased from 283.25 MPa to 344.98–361.51 MPa,and the elongation increased from 3.61%to 9.58–14.10%.The potential mechanism of the microstructure evolution and strength improvement was *** research will provide new insights into the available metal matrix composites by laser additive manufacturing(LAM).

关键词： Laser additive manufacturing Aluminum matrix composites Mechanical property Microstructure

A Comparative Study on the Microstructure and Properties of ITO Targets and Thin Films Prepared from Two Different Powders

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Acta Metallurgica Sinica(English Letters) 2021年第5期34卷 675-693页

作者： Fangsheng Mei Tiechui Yuan ruidi li Jingwei Huang Powder Metallurgy Research Institute Central South UniversityChangsha410083China Science and Technology on High Strength Structural Materials Laboratory Central South UniversityChangsha410083China

With the rapid development of indium tin oxide(ITO)in the electronic display industry,choosing which raw powders to prepare high-quality ITO targets has always been a controversial *** the work,in order to clearly understand the effect of the raw powders on the microstructure and properties of ITO targets and thin films,tin-doped indium oxide(dITO)and In_(2)O_3-SnO_(2)mixed(mITO)powders were chosen to prepare ITO targets for depositing the films and a comparative study on their microstructure and properties was *** is found that,(1)dITO targets possess a higher solid solubility of tin in indium oxide and more uniform elemental distribution,while there are a higher density,a finer grain size and a higher mass ratio of In_(2)O_3 to SnO_(2)for the mITO targets;(2)dITO films with more coarser columnar grains and a rougher surface prefer to grow along the[100]direction in an Ar atmosphere;(3)the conductive property of ITO films only depends on the doping amount of tin and is independent of the raw powders and the preparation process of the target source;(4)dITO films possess the superior optical property and narrower optical band gap;(5)the etching property of mITO films is superior to that of dITO films due to the lower solid solubility of tin in indium oxide.

关键词： Tin-doped indium oxide In_(2)O_3-SnO_(2) mixed powder Solid solubility of tin in indium oxide Photoelectric property Etching property

Influence of rare earth oxides on microstructure and mechanical properties of nickel-based superalloys fabricated by high energy beam processing:A review

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Journal of Rare Earths 2024年第9期42卷 1629-1645,I0001页

作者： lianjie Bi Hua Yan Peilei Zhang Haichuan Shi Zhiyuan li ruidi li School of Materials Science and Engineering Shanghai University of Engineering ScienceShanghai201620China College of Agricultural Science and Engineering Hohai UniversityNanjing211100China Department of Mechanics and Maritime Science Chalmers University of TechnologyGothenburSE41296Sweden State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China

In this paper,the effects of rare earth oxides on the micro structure and mechanical properties of nickelbased superalloys prepared by high-energy beam processing technology were critically *** focus is on the optimal amount of rare earth oxides that can produce ideal *** attention was paid to their main strengthening mechanisms,including solid solution strengthening mainly in the form of solid solution dissolved in the nickel-based alloy and improving the microstructure of the alloy by grain refinement or fine grain strengthening produced by homogenizing the distribution phase.Y_(2)O_(3),La_(2)O_(3) and CeO_(2) rare earth oxides can also improve the fluidity of the alloy molten pool and reduce the segregation of alloying *** advantages can significantly improve the mechanical properties of the ***,this paper outlines the future research directions of rare earth oxides,aiming to expand their application potential.

关键词： Rare earths High energy beam Nickel-based superalloys Microstructure Mechanical properties

Microstructure and mechanical properties of Al-Si-Ni coating on Cu-Cr substrate prepared by multi-permeation and friction stir processing

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Nano Materials Science 2019年第3期1卷 224-228页

作者： Yin Wang ruidi li Tiechui Yuan State Key Laboratory of Powder Metallurgy Shenzhen Institute of Central South University Central South University

The surface of copper-chromium alloy was processed by Al-Si-Ni multi-permeation and friction stir processing,and the microstructure and mechanical properties of the surface layer were tested by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),microhardness tester and friction testing *** results show that Al,Si and Ni elements are fully permeated into the surface of copper-chromium alloy after multielement co-infiltration and friction stir *** the observation of the microstructures,we found that the reticular structure is fragmented and distributed in the stir zone *** becomes finer and grains *** micro hardness of the copper-chromium alloy increased to 129 HV,44.9%higher than that of the original *** main reasons of microhardness enhancement are solid solution strengthening,fine grains strengthening and dispersion *** friction test results show that the friction coefficient is basically stable at 0.69 and the wear mass is only 0.0017 g after 10 min of friction *** improvement of wear resistance was attributed to the increase of microhardness of the alloy surface.

关键词： Copper-chromium alloy Al-Si-Ni multi-permeation Friction stir processing Microstructure Mechanical properties

Microstructure and Mechanical Properties of Selective Laser Melted Al–2.51Mn–2.71Mg–0.55Sc–0.29Cu–0.31Zn Alloy Designed by Supersaturated Solid Solution

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Acta Metallurgica Sinica(English Letters) 2022年第3期35卷 354-368页

作者： Minbo Wang ruidi li Tiechui Yuan Haiou Yang Pengda Niu Chao Chen State Key Laboratory of Powder Metallurgy Shenzhen Research Institute of CSUCentral South UniversityChangsha 410083China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China

Selective laser melting(SLM)of aluminium alloys for lightweight application is arousing widespread interest,but the available alloy compositions are limited due to unsatisfactory mechanical *** rapid solidifi cation of SLM provides a pathway to design a novel alloy composition with extended *** strategy is demonstrated by an additively manufactured novel Al–2.51 Mn–2.71 Mg–0.55 Sc–0.29 Cu–0.31 Zn alloy with the supersaturated solid solution in the present *** microstructure of as-build sample is characterized with multi-modal grains with the fi ne equiaxed grain(FEG,~800 nm)at molten pool boundaries,coarse equiaxed grain(CEG,~2μm)and columnar dendrites(CD,~4μm)inside the molten pool,which relates to the precipitations type and *** is observable that Al 3(Sc,Zr)precipitation particles with the size of~50 nm are dispersed in the FEG zone,while the interior of CEG shows no Al3(Sc,Zr)particle which only exists at the CEG *** of FEG,CEG or CD,the slender Al6 Mn precipitation with the length of~500 nm is distributed along the grain ***,a lot of vacancies and thickness fringes are detected in the FEG zone,which confi rms the supersaturated solid solution in laser rapid solidifi *** ultimate tensile strength and yield strength of the as-printed sample are~380 MPa and~330 MPa,respectively,with elongation~14%,which increase to~440 MPa and~410 MPa with a reduction of elongation to~9%after heat treatment.

关键词： Selective laser melting Al–2.51Mn–2.71Mg–0.55Sc–0.29Cu–0.31Zn Supersaturated solid solution Microstructure Mechanical property Precipitation

Formation mechanism of inherent spatial heterogeneity of microstructure and mechanical properties of NiTi SMA prepared by laser directed energy deposition

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International Journal of Extreme Manufacturing 2023年第3期5卷 548-567页

作者： MengJie Luo ruidi li Dan Zheng JingTao Kang HuiTing Wu ShengHua Deng PengDa Niu State Key Laboratory of Powder Metallurgy Central South UniversityChangshaHunan 410083People’s Republic of China Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou 341000People’s Republic of China

Ni51Ti49 at.%bulk was additively manufactured by laser-directed energy deposition(DED)to reveal the microstructure evolution,phase distribution,and mechanical *** is found that the localized remelting,reheating,and heat accumulation during DED leads to the spatial heterogeneous distribution of columnar crystal and equiaxed crystal,a gradient distribution of Ni4Ti3 precipitates along the building direction,and preferential formation of Ni4Ti3 precipitates in the columnar *** austenite transformation finish temperature(Af)varies from-12.65℃(Z=33 mm)to 60.35℃(Z=10 mm),corresponding to tensile yield strength(σ0.2)changed from 120±30 MPa to 570±20 MPa,and functional properties changed from shape memory effect to superelasticity at room *** sample in the Z=20.4 mm height has the best plasticity of 9.6%and the best recoverable strain of 4.2%.This work provided insights and guidelines for the spatial characterization of DEDed NiTi.

关键词： shape memory alloy gradient functional materials laser directed energy deposition spatial heterogeneity additive manufacturing mechanical properties

Review on laser directed energy deposited aluminum alloys

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International Journal of Extreme Manufacturing 2024年第2期6卷 84-131页

作者： Tian-Shu liu Peng Chen Feng Qiu Hong-Yu Yang Nicholas Tan Yew Jin Youxiang Chew Di Wang ruidi li Qi-Chuan Jiang Chaolin Tan Singapore Institute of Manufacturing Technology(SIMTech) Agency for ScienceTechnology and Research(A∗STAR)5 Cleantech LoopSingapore 636732Singapore State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130025People’s Republic of China Key Laboratory of Automobile Materials Ministry of Education and Department of Materials Science and EngineeringJilin UniversityChangchun 130025People’s Republic of China School of Mechanical&Automotive Engineering South China University of TechnologyGuangzhou 510640People’s Republic of China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083People’s Republic of China

lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al *** a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and ***,LDED Al alloys are highly challenging due to their inherent poor printability(*** laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al *** porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al *** parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al *** underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are *** benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are *** review aims to provide a critical and in-depth evaluation of current progress in LDED Al *** opportunities and perspectives in LDED high-performance Al alloys are also outlined.

关键词： additive manufacturing laser directed energy deposition(LDED) aluminum alloys printability aluminum matrix composite auxiliary fields mechanical properties

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增材制造马氏体时效钢的研究进展

中国激光 2022年第14期49卷 15-28页

作者：李虎赵伟江李瑞迪刘咏中南大学粉末冶金研究院粉末冶金国家重点实验室湖南长沙410083

综述了增材制造马氏体时效钢的研究进展,包括增材制造工艺和后处理对力学性能和微观组织的影响以及异质结构马氏体时效钢和梯度结构马氏体时效钢的力学性能和组织结构特点。此外,还总结了增材制造马氏体钢的合金成分、主要作用及其设计... 详细信息

综述了增材制造马氏体时效钢的研究进展,包括增材制造工艺和后处理对力学性能和微观组织的影响以及异质结构马氏体时效钢和梯度结构马氏体时效钢的力学性能和组织结构特点。此外,还总结了增材制造马氏体钢的合金成分、主要作用及其设计思路,分析了合金成分对马氏体时效钢的力学性能和微观组织的影响,着重讨论了复合颗粒增强相在增材制造马氏体时效钢中的强化效果与强化机制。介绍了增材制造马氏体时效钢在随形冷却模具、激光熔覆修复技术和表面涂层或表面改性等领域中的应用,并对增材制造马氏体时效钢在未来的发展方向进行了展望。

关键词：激光技术增材制造激光粉末床熔合马氏体时效钢模具钢异质结构钢

Microstructures and Mechanical Properties of Al-Mg-Sc-Zr Alloy Additively Manufactured by Laser Direct Energy Deposition

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Chinese Journal of Mechanical Engineering(Additive Manufacturing Frontiers) 2022年第4期1卷 16-26页

作者： Qian Hua Wenjun Wang ruidi li Hongbin Zhu Zehuan lin Rong Xu Tiechui Yuan Kai liu State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China Shenzhen Institute of Central South University Shenzhen518057China CRRC Industrial Academy Co.Ltd. Beijing100070China School of Materials Science and Engineering Wuhan University of TechnologyWuhan430070China

An Al-Mg-Sc-Zr alloy was additively manufactured by laser direct energy deposition(DED)under different laser powers,and the microstructures and mechanical properties of the as-deposited samples were *** samples showed a fully equiaxed grain structure with grain sizes of 2–30μ*** of the blocky primary Al3(Sc,Zr)-precipitated phases(lic heat treatment during the DED forming *** to the EBSD(Electron backscatter diffraction)results,the texture index and strength of the sample were only slightly greater than 1,indicating that the material structure exhibited a certain but not obvious *** sample in the horizontal direction had better yield strength,tensile strength,and elogation properties(399.87 MPa,220.96 MPa,9.13%)than that in the building direction(385.40 MPa,219.40 MPa,8.24%),although the sample in the〈XOZ〉plane had the finest equiaxed *** ductility of the〈XOZ〉sample deteriorated as the number of pores increased.

关键词： Direct energy deposition Al-Mg-Sc-Zr alloy Microstructure Mechanical properties

Nitrogen-doping assisted local chemical heterogeneity and mechanical properties in CoCrMoW alloys manufactured via laser powder bed fusion

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Advanced Powder Materials

Advanced Powder Materials 2024年第5期3卷 46-57页

作者： Wenting Jiang ruidi li Junyang He Song Ni li Wang Zibin Chen Yi Huang Caiju li Jianhong Yi Min Song State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China College of Materials and Advanced Manufacturing Hunan University of TechnologyZhuzhou 412007China Research Institute for Advanced Manufacturing Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHong KongChina Department of Design and Engineering Faculty of Science and TechnologyBournemouth UniversityPooleDorsetBH125BBUK Materials Research Group Department of Mechanical EngineeringUniversity of SouthamptonSouthamptonSO171BJUK Faculty of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China

CoCrMoW alloys with different nitrogen(N)additions(0,0.05,0.1,and 0.2 wt%)were prepared via laser powder bed fusion(LPBF).The effects of N content on the microstructure and mechanical properties were *** results indicate that the LPBFed CoCrMoW alloy with 0.1 wt%N addition(0.1 N alloy)shows the best combination of mechanical properties with a yield strength of~983 MPa and an elongation of~19%.Both the LPBF process and the N addition impose great effects on suppressing theγtoεmartensitic transformation,resulting in a decrease in the width and amount ofεlaths/stacking ***,the N addition promotes the segregation of elements Mo,W,and Si along the cellular sub-grain boundaries(CBs),forming fine and discontinuous precipitates rich in Mo,W and Si along the CBs in the 0.1 N alloy,but dense and continuous(Mo,W)5Si_(3)precipitates along the CBs in the 0.2 N ***(Mo,W)5Si_(3)precipitates with a tetragonal structure were observed and characterized for the first time in the Co-Cr based *** negative mixing enthalpy between the non-metallic elements N,Si and the metallic elements Mo,W,Cr,and the rapid solidification induced segregation of high melting point elements such as Mo and W along CBs during LPBF process,synergistically contribute to the chemical heterogeneity in the *** pure FCC matrix,the slightly increased segregation of Mo,W,Si elements and fine precipitates along the CBs contribute to the good combination of strength and elongation of the 0.1 N ***,though pure FCC phase was present in the 0.2 N alloy,the dense and continuous(Mo,W)5Si_(3)precipitates along CBs acted as nucleation sites for cracks,deteriorating the elongation of the ***,it is possible to tune the mechanical properties of the LPBFed CoCrMoW alloy by adjusting the local chemical heterogeneity.

关键词： CoCrMoW alloy Laser powder bed fusion Nitrogen addition Mechanical properties Precipitation behaviors