Nanostructured Materials最新文献_第3页

Deformation-induced nonequilibrium grain-boundary phase in submicrocrystalline iron 亚微晶铁中变形诱导的非平衡晶界相

Nanostructured Materials Pub Date : 1999-11-01 Epub Date: 2000-05-19 DOI: 10.1016/S0965-9773(99)00383-9

V.A. Shabashov , V.V. Ovchinnikov , R.R. Mulyukov , R.Z. Valiev , N.P. Filippova

{"title":"Deformation-induced nonequilibrium grain-boundary phase in submicrocrystalline iron","authors":"V.A. Shabashov , V.V. Ovchinnikov , R.R. Mulyukov , R.Z. Valiev , N.P. Filippova","doi":"10.1016/S0965-9773(99)00383-9","DOIUrl":"https://doi.org/10.1016/S0965-9773(99)00383-9","url":null,"abstract":"<div>The shapes of Mössbauer spectra of coarse-grained annealed armco iron and submicrocrystalline (SMC) iron with a grain size of 0.22 μm were compared. The SMC was made from the armco iron by pressure shear and subsequent annealing at 420 °C. We intended to separate an additional subspectrum, which appears as a result of the grain refinement. That subspectrum was attributed to grain-boundary atoms or the “grain-boundary phase” (GBP). The volume fraction of that phase was determined. On the average, the GBP interatomic spacing was suggested to be 1% larger than that of the grain phase (GP) and the presence of considerable compressive stresses in the GBP were deduced. A possible reason for the satellite subspectrum appearing after the grain refinement was that it was attributed to a sudden change in the fundamental characteristics of the solid at a certain critical value of the lattice parameter, which varies continuously in going from the geometrical boundary to the grain center.</div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":"11 8","pages":"Pages 1017-1029"},"PeriodicalIF":0.0,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00383-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91746233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 13

Processing, microstructure and mechanical properties of 25 vol% YAG-Al2O3 nanocomposites 25 vol% YAG-Al2O3纳米复合材料的制备、显微组织和力学性能

Nanostructured Materials Pub Date : 1999-11-01 Epub Date: 2000-05-19 DOI: 10.1016/S0965-9773(99)00396-7

W.Q Li , L Gao

{"title":"Processing, microstructure and mechanical properties of 25 vol% YAG-Al2O3 nanocomposites","authors":"W.Q Li , L Gao","doi":"10.1016/S0965-9773(99)00396-7","DOIUrl":"https://doi.org/10.1016/S0965-9773(99)00396-7","url":null,"abstract":"<div>A co-precipitation method was investigated to manufacture 25 vol% YAG-Al2O3 nanocomposites with excellent strength characteristics at room temperature. The as-prepared powders were sintered by hot-pressing in N2 to nearly full density with heating rate of 10°Cmin−1 to 1400°C for 1h and at 30MPa pressure. The microstructure was characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and transmission electron microscope (TEM). Microstructural results of hot-pressed composites reveal that the intergranular YAG grains of micrometer size (≈800nm) were dispersed at the grain boundaries of a dense Al2O3 matrix, and most fine grain YAG grains of nanometric size (≈100nm) were entrapped within the Al2O3 grains in the composite. The room temperature fracture strength and fracture toughness of the hot-pressed composites were 611MPa and 4.53MPa·m−1/2, respectively. These strength and fracture toughness values are higher than those reported in other studies for YAG-Al2O3 system. It is proposed that the improvement of mechanical property of hot-pressed nanocomposites is due to the reduction of the grain size of the matrix and the improved strength of the grain boundaries in 25 vol% YAG-Al2O3 nanocomposite.</div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":"11 8","pages":"Pages 1073-1080"},"PeriodicalIF":0.0,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00396-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91746240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 58

Synthesis of monodisperse Au, Pt, Pd, Ru and Ir nanoparticles in ethylene glycol 单分散Au, Pt, Pd, Ru和Ir纳米颗粒在乙二醇中的合成

Nanostructured Materials Pub Date : 1999-11-01 Epub Date: 2000-05-19 DOI: 10.1016/S0965-9773(99)00419-5

F Bonet , V Delmas , S Grugeon , R Herrera Urbina , P-Y Silvert , K Tekaia-Elhsissen

引用次数: 315

Structural stability of titania thin films 二氧化钛薄膜的结构稳定性

Nanostructured Materials Pub Date : 1999-11-01 Epub Date: 2000-05-19 DOI: 10.1016/S0965-9773(99)00413-4

P.I Gouma , P.K Dutta , M.J Mills

引用次数: 61

Comparison of grain size distributions obtained by XRD and TEM in milled FCC powders 用XRD和TEM比较了FCC粉的粒度分布

Nanostructured Materials Pub Date : 1999-11-01 Epub Date: 2000-05-19 DOI: 10.1016/S0965-9773(99)00410-9

J. Guerrero-Paz , D. Jaramillo-Vigueras

{"title":"Comparison of grain size distributions obtained by XRD and TEM in milled FCC powders","authors":"J. Guerrero-Paz , D. Jaramillo-Vigueras","doi":"10.1016/S0965-9773(99)00410-9","DOIUrl":"https://doi.org/10.1016/S0965-9773(99)00410-9","url":null,"abstract":"<div>Measurements of grain size in powders of the Cu-15at%Al, Cu-20at%Ni, Cu and Ni systems, milled for different times were conducted. X-ray diffraction (XRD) (Warren-Averbach method) and transmission electron microscopy were used for that purpose. From both techniques, distributions of grain diameter (length) were obtained, which permitted to compare both results. Such results were interpreted by considering previous studies of particle size evolution and microstructural evolution. A better comprehension of phenomena that occur in the mechanical alloying, as the grain refinement and the solid solution formation, is attained.The grain size results obtained by the two techniques were coincident for the Cu-15at%Al system. This system did not present adherence of the powders to the milling media. In the case of the Cu-20at%Ni, Cu and Ni systems, that presented adherence, the results were coincident solely in the powder milled for 864 ks. This is explained due to the microstructural homogenization, reached until that time.The grain size as a function of the milling time of the two classes of FCC systems, being referred to the adherence phenomenon, presented opposed trends. For example, for the Cu-at15at%Al system, the 70% of the population of grains had a grain size smaller than 7.5, 12 and 20 nm for the milling times of 180, 360 and 864 ks respectively. In the case of the Cu-20at%Ni, Cu and Ni systems, the 70% of the population of grains had a grain size smaller than 35, 22 and 16 nm for the milling times of 180, 360 and 864 ks respectively. These contrary trends reflect different mechanisms of grain size refinement.A maximum value of grain size of 20 nm required to form the solid solution in the Cu-at15%Al and Cu-20%atNi systems was found.</div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":"11 8","pages":"Pages 1195-1204"},"PeriodicalIF":0.0,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00410-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91746581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 19

The effect of Ni on the cryogenic attritor milling of Metglas Fe78B13Si9 Ni对meglas Fe78B13Si9低温磨耗器铣削的影响

Nanostructured Materials Pub Date : 1999-11-01 DOI: 10.1016/S0965-9773(00)00428-1

Baoquan Huang, H. Jiang, R. Perez, S. Nutt, E. Lavernia

引用次数: 4

Synthesis of powders and films using a new laser ablation technique 用激光烧蚀新技术合成粉末和薄膜

Nanostructured Materials Pub Date : 1999-11-01 DOI: 10.1016/S0965-9773(99)00406-7

R. Houriet, R. Vacassy, H. Hofmann

引用次数: 17

Surfaces of doped nanophase cerium oxide catalysts 掺杂纳米相氧化铈催化剂的表面

Nanostructured Materials Pub Date : 1999-11-01 Epub Date: 2000-05-19 DOI: 10.1016/S0965-9773(00)00431-1

A.E.C Palmqvist , M Wirde , U Gelius , M Muhammed

{"title":"Surfaces of doped nanophase cerium oxide catalysts","authors":"A.E.C Palmqvist , M Wirde , U Gelius , M Muhammed","doi":"10.1016/S0965-9773(00)00431-1","DOIUrl":"https://doi.org/10.1016/S0965-9773(00)00431-1","url":null,"abstract":"<div>Solid solutions of nanophase cerium oxides have been prepared and the relationship between their bulk crystal structure and surface characteristics has been studied at room temperature with X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Dopants with a valence lower than +4, such as Ca2+, Nd3+, and Pb2+, introduce structural defects (oxygen vacancies) in the cerium oxide lattice, which has been found to affect the redox catalytic activity of the materials. The introduction of oxygen vacancies leads to the appearance of an O1s core level peak with a shift of 2.0–2.5 eV to higher binding energies as compared to the core level peak of the lattice oxygen in CeO2. The intensity of this high binding energy O1s peak varies with the expected concentration of oxygen vacancies in the surface, the type of dopant cation and its concentration in the solid solution. It was found that carbonate and hydroxide species are responsible for the appearance of this O1s peak, presumably as a result of capping of oxygen vacancies at the surface. The implications of these surface groups on the catalytic activity of the materials are discussed.</div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":"11 8","pages":"Pages 995-1007"},"PeriodicalIF":0.0,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(00)00431-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91746231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 86

Preparation of nanoscale α-Al2O3 powder by the polyacrylamide gel method 聚丙烯酰胺凝胶法制备纳米级α-Al2O3粉体

Nanostructured Materials Pub Date : 1999-11-01 Epub Date: 2000-05-19 DOI: 10.1016/S0965-9773(99)00417-1

H Wang , L Gao , Weiqun li , Qiang li

引用次数: 40

Cluster size effect observed for gold nanoparticles synthesized by sol-gel technique as studied by X-ray photoelectron spectroscopy 用x射线光电子能谱研究溶胶-凝胶法制备金纳米颗粒的团簇尺寸效应

Nanostructured Materials Pub Date : 1999-11-01 Epub Date: 2000-05-19 DOI: 10.1016/S0965-9773(99)00409-2

S Shukla , S Seal

引用次数: 80