检索结果-南通市图书馆

Effects of welding speed on the multiscale residual stresses in frictionstir welded metal matrix composites

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第5期35卷 824-832页

作者： X.X.Zhang L.H.Wu H.ANDra W.M.Gan M.Hofmann D.Wang D.R.Ni B.L.Xiao Z.Y.Ma Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Fraunhofer Institute for Industrial Mathematics Fraunhofer-Platz 1 Kaiserslautern 67663 Germany German Engineering Materials Science Centre Helmholtz-Zentrum Geesthacht D-21502 Geesthacht Germany Heinz Maier-Leibnitz Zentrum (MLZ) Technische Universitat Munchen D-85747 Garching Germany

The effects of welding speed on the macroscopic and microscopic residual stresses(RSes) in friction stir welded 17 vol.% SiCp/2009 Al-T4 composite plates were studied via neutron diffraction and an improved decoupled hierarchical multiscale modeling methods. Measurements showed that the macroscopic and total RSes had the largest variations in the longitudinal direction(LD). Increasing the welding speed led to higher values of measured LD macroscopic and total RSes in the matrix. The welding speed also significantly influenced the distributions and magnitudes of the microscopic RSes. The RSes were predicted via an improved hierarchical multiscale model, which includes a constant coefficient of friction based thermal model. The RSes in the composite plates before friction stir welding(FSW) were computed and then set as the initial states of the FSW process during modeling. This improved decoupled multiscale model provided improved predictions of the temperature and RSes compared with our previous model.

关键词： metal-matrix composites (MMCs) Friction stir welding Residual/internal stress Neutron diffraction Finite element analysis (FEA) Multiscale simulation

A study of interparticulate strain in a hot-extruded SiC_p/2014 Al composite

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,metallurgy and Materials 2019年第4期26卷 523-529页

作者： Ying Hu Qiu-bao Ou-yang Lei Yao Sheng Chen Lan-ting Zhang School of Materials Science and Engineering Shanghai Jiao Tong University Support Department of Research Institute (R&D Center) Baoshan Iron & Steel Co.Ltd. State Key Laboratory of metal matrix Composites Shanghai Jiao Tong University Materials Genome Initiative Center Shanghai Jiao Tong University

We report a correlative study of strain distribution and grain structure in the Al matrix of a hot-extruded SiC particulate-reinforced Al composite(SiC_p/2014 Al). Finite element method(FEM) simulation and microstructure characterization indicate that the grain structure of the Al matrix is affected by the interparticulate strain distribution in the matrix during the process. Both electron-backscattered diffraction(EBSD) and selected-area electron diffraction(SAED) indicated localized misorientation in the Al matrix after hot extrusion. Scanning transmission electron microscopy(STEM) revealed fine and recrystallized grains adjacent to the Si C particulate and elongated grains between the particulates. This result is explained in terms of recrystallization under an interparticulate strain distribution during the hot extrusion process.

关键词： metal-matrix composites strain distribution recrystallization grain structure

Microstructure and mechanical properties of Ti-6Al-4V-5% hydroxyapatite composite fabricated using electron beam powder bed fusion

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第2期35卷 309-321页

作者： César A.Terrazas Lawrence E.Murr Diego Bermudez Edel Arrieta David A.Roberson Ryan B.Wicker W.M.Keck Center for 3D Innovation The University of Texas at El PasoEl PasoTX 79968USA Department of Mechanical Engineering The University of Texas at El PasoTX 79968USA Department of metallurgical Materials and Biomedical EngineeringThe University of Texas at El PasoTX 79968USA

A novel, Ti-6 Al-4 V(Ti64)/Hydroxyapatite(HA at 5% by weight concentration) metal/ceramic composite has been fabricated using electron beam powder bed fusion(EPBF) additive manufacturing(AM): specifically, the commercial electron beam melting(EBM?) process. In addition to solid Ti64 and Ti64/5% HA samples, four different unit cell(model) open-cellular mesh structures for the Ti64/5% HA composite were fabricated having densities ranging from 0.68 to 1.12 g/cm^3, and corresponding Young's moduli ranging from 2.9 to 8.0 GPa, and compressive strengths ranging from ~3 to 11 MPa. The solid Ti64/5%HA composite exhibited an optimal tensile strength of 123 MPa, and elongation of 5.5% in contrast to a maximum compressive strength of 875 MPa. Both the solid composite and mesh samples deformed primarily by brittle deformation, with the mesh samples exhibiting erratic, brittle crushing. Solid, EPBF-fabricated Ti64 samples had a Vickers microindentation hardness of 4.1 GPa while the Ti64/5%HA solid composite exhibited a Vickers microindentation hardness of 6.8 GPa. The lowest density Ti64/5%HA composite mesh strut sections had a Vickers microindentation hardness of 7.1 GPa. Optical metallography(OM) and scanning electron microscopy(SEM) analysis showed the HA dispersoids to be highly segregated along domain or grain boundaries, but homogeneously distributed along alpha(hcp) platelet boundaries within these domains in the Ti64 matrix for both the solid and mesh composites. The alpha platelet width varied from ~5 μm in the EPBF-fabricated Ti64 to ~1.1 m for the Ti64/5%HA mesh strut. The precursor HA powder diameter averaged 5 μm, in contrast to the dispersed HA particle diameters in the Ti64/5%HA composite which averaged 0.5 m. This work highlights the use of EPBF AM as a novel process for fabrication of a true composite structure, consisting of a Ti64 matrix and interspersed and exposed HA domains, which to the authors' knowledge has not been reported before. The results also illu

关键词： Hydroxyapatite (HA) metal-matrix ceramic composites Open-cellular (mesh) structures Electron-beam powder bed fusion (EPBF) Additive manufacturing (AM) Mechanical properties Microstructure characterization

The improved mechanical properties of Al matrix composites reinforced with oriented β-Si3N4 whisker

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第7期35卷 1345-1353页

作者： Chenxu Zhang Yu-Ping Zeng Dongxu Yao Jinwei Yin Kaihui Zuo Yongfeng Xia Hanqin Liang State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China University of Chinese Academy of Sciences Beijing 100049China

The β-Si3N4 whiskers (β-Si3N4w) reinforced A1 matrix com posites were first fabricated by hot pressing, then treated through hot extrusion. The microstructure characterization dem onstrated the preferred orientations of both β-Si3N4w and A1 grains in the as-extruded composites. It indicated th at β-Si3N4w were aligned along the extrusion direction and A1 grains exhibited a distinct ai texture. The interface betw een β-Si3N4w and A1 was in a good bonding status without voids and reaction products. Effects of extrusion process on the mechanical properties of com posites were also investigated. The results indicated the extrusion process had a prom inent strengthening effect on the mechanical properties of composites. The maxim umyield strength and ultim ate tensile strength of com posites reached up to 170 and 289 MPa, respectively, accompanied by a 12.3% elongation at fracture w hen the w hisker fraction was 15 vol.%. This im provem ent was collectively attributed to the densification of composites, the strong interface, and the preferred orientation inside composites. The yield strength of the composites reinforced with 5 vol.%β-Si3N4w corresponded well w ith the theoretical value from different strengthening mechanisms.

关键词： metal-matrix composites (MMC) β-Si3N4 whiskers Preferred orientation Interface Mechanical properties Extrusion

High-Speed Friction Stir Welding of T6-Treated B4Cp/6061Al Composite

在线全文

学校读者我要写书评

暂无评论

Acta metallurgica Sinica(English Letters) 2020年第1期33卷 67-74页

作者： Y.Z.Li Y.N.Zan Q.Z.Wang B.L.Xiao Z.Y.Ma Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China University of Science and Technology of China Shenyang 110016China

T6-treated 20 wt% B4 Cp/6061 Al sheets were joined under welding speeds of 400–1200 mm/min by friction stir welding(FSW) with a threaded cermet pin. The macro-defect-free FSW joints could be achieved at high welding speeds up to 1200 mm/min, but larger plunge depth was required at the welding speeds of 800 and 1200 mm/min to eliminate the tunnel defect. In the nugget zone(NZ) of the joints, the B4 C particles were broken up and uniformly redistributed. The NZ exhibited lower hardness than the base metal(BM), and the hardness value almost did not change with increasing welding speed, attributable to the dissolution of precipitates. Compared with the BM, the joints showed lower tensile strength. As the welding speed increased from 400 to 800 mm/min, the joint efficiencies were nearly the same and up to ~ 73%. When the welding speed increased up to 1200 mm/min, the tensile strength significantly decreased, due to the occurrence of kissing bond defect at the bottom of the NZ. With increasing welding speed, the fracture location of the joints transferred gradually from the heat-affected zone to the NZ due to the kissing bond defects.

关键词： metal-matrix composites Microstructures Mechanical properties Friction stir welding High-speed welding

Improvement of mechanical properties of Sn-58Bi alloy with multi-walled carbon nanotubes

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2012年第S3期22卷 692-696页

作者： HE Peng Lü Xiao-chun LIN Tie-song LI Hai-xin AN Jing MA Xin FENG Ji-cai ZHANG Yan LI Qi QIAN Yi-yu State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Department of Materials Science and Engineering Shenzhen Graduate SchoolHarbin Institute of Technology Yik Shing Tat Industrial Company Limited CNano Technology (Beijing) Limited

Carbon nanotubes (CNTs) reinforced Sn-58Bi composites were successfully fabricated through ball-milling method and low temperature melting *** influence of multi-walled carbon nanotubes (MWCNTs) on the mechanical strength and ductility of Sn-58Bi lead-free alloy was *** mechanical test results show that the bending strength of Sn-58Bi-0.03CNTs (mass fraction,%) composite is increased by 10.5% than that of the Sn-58Bi alloy,which can be attributed to the reduction of Sn-rich segregation and the grain *** toughness of Sn-58Bi-0.03CNTs composite is increased by 48.9% than that of the matrix *** is indicated that the influence of CNTs on the strength of Sn-58Bi-xCNTs composite is *** addition,the fracture mechanism of CNTs reinforced Sn Bi composite was *** corresponding fracture surface comparison between the Sn-58Bi-0.03CNTs composite and the monolithic Sn-58Bi alloy was made to identify the influence of CNTs on the fracture behavior and the reinforcing effect of CNTs.

关键词： carbon nanotubes metal-matrix composites mechanical properties fracture mechanism

Microstructure and wear characteristics of ATZ ceramic particle reinforced gray iron matrix surface composites

在线全文

学校读者我要写书评

暂无评论

China Foundry 2018年第3期15卷 167-172页

作者： Xue Ma Liang-feng Li Fan Zhang Zu-hua Zhang Hao Wang En-ze Wang School of Materials Science and Engineering Southwest University of Science and Technology Chengdu Aerospace Superalloy Technology Co. Ltd Centre for Future Materials University of Southern Queensland

The alumina toughened zirconia(ATZ) ceramic particle reinforced gray iron matrix surface composite was successfully manufactured by pressureless infi ltration. The porous preform played a key role in the infi ltrating progress. The microstructure was observed by scanning electron microscopy(SEM); the phase constitutions was analyzed by X-ray diffraction(XRD); and the hardness and wear resistance of selected specimens were tested by hardness testing machine and abrasion testing machine, respectively. The addition of high carbon ferrochromium powders leads to the formation of white iron during solidifi cation. The wear volume loss rates of ATZ ceramic particle reinforced gray iron matrix surface composite decreases fi rst, and then tends to be stable. The wear resistance of the composite is 2.7 times higher than that of gray iron matrix. The reason is a combination of the surface hardness increase of gray iron matrix and ATZ ceramic particles and alloy carbides protecting effect on gray iron matrix.

关键词： metal-matrix surface composites pressureless infiltrating particle-reinforcement surface alloying wear testing

Optimized Distribution and Morphology of Carbon Nanofibers for a Field Emitter Grown by Nickel and Chromium Cosputtering

在线全文

学校读者我要写书评

暂无评论

Materials Sciences and Applications 2013年第4期4卷 225-230页

作者： Norihiro Shimoi Shun-Ichiro Tanaka Graduate School of Environmental Studies Tohoku University of Aoba Sendai Japan Institute of Multidisciplinary Research for Advanced Materials Tohoku University Katahira Sendai Japan

To obtain a high field emission (FE) current with a low driving voltage, it is important to control and optimize carbon nanofiber (CNF) array patterns for FE. While there have been various means for controlling CNF array patterns reported over the past few decades, array patterning using lithography is the method typically used to control CNF morphology. Because lithography uses many masks and is costly, it is necessary to establish a simpler process. In this study, the grain size and distribution of catalysts with phase separation were controlled. A system which controls the morphology of small bundles of CNFs was constructed with the distance between the bundles kept constant in order to obtain a higher FE current. The Ni catalyst layer for forming the CNF morphology was separated by noncatalytic Cr grains formed by cosputtering. As a result, it was possible to control the Ni content, the grain size and synthesis density of CNFs in the alloy with a varying number of nickel pellets placed on the chromium target. This method is an epochmaking CNF patterning technique very different from lithography.

关键词： Alloys Carbon Fibres metal-matrix Composites X-Ray Diffraction Chemical Vapour Deposition (CVD)

Evaluation of Characteristics of Interfacial Phases Produced in Al/Ni<sub>3</sub>Al Composite during Manufacturing

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Materials Sciences and Applications 2011年第9期2卷 1340-1348页

作者： Seyed Abdolkarim Sajjadi Maryam Abbasi Mazyar Azadbeh 不详

metal matrix composites (MMCs) are currently being investigated because of their superior properties. The properties are mainly attributed to the efficiency of the load transfer from the matrix to the reinforcements through the matrix-reinforcement interface. The aim of this study is to investigate the effect of manufacturing parameters on the microstructure and morphology of the interface and the aluminide phases formed at the matrix-reinforcement interfaces. The parameters are: milling time to fabricate Ni3Al, method of mixing of Ni3Al and Al powders, compaction pressure and sintering temperature. The composite studied in this research was Al/5 Vol% Ni3Al made from two different types of Ni3Al powders. The results showed that compacting and sintering at higher levels lead to the transformation of Ni3Al particles to thin layers of Al3Ni. It was also shown that the prolonged milling time to produceNi3Alreinforcements and the prolonged ball milling procedure for mixing the powders, both, promote the diffusion process at reinforcement/matrix interface.

关键词： metal-matrix Composites (MMCs) Interface X-Ray Diffraction (XRD) Powder Processing