Nanoindentation investigation of the mechanical behaviors of nanoscale Ag/Cu multilayers

2007 ◽  
Vol 22 (12) ◽  
pp. 3423-3431 ◽  
Author(s):  
S.P. Wen ◽  
R.L. Zong ◽  
F. Zeng ◽  
Y. Gao ◽  
F. Pan
Keyword(s):  
Deformation Mechanism ◽  
Shear Bands ◽  
Grain Boundary Sliding ◽  
Indentation Creep ◽  
X Ray Diffraction ◽  
Petch Relationship ◽  
Size Dependent ◽  
Transmission Electron ◽  
20 Nm ◽  
Hardness Values

The microstructure, hardness, elastic modulus, and indentation creep of Ag/Cu multilayers prepared by magnetron sputtering were investigated by x-ray diffraction, transmission electron microscopy, and nanoindentation. The hardness values obey the Hall–Petch relationship as the periodicity decreases to 20 nm. For multilayers with periodicity smaller than 20 nm, the Hall–Petch relationship breaks down and the hardness values saturate at about 4.6 GPa; moreover, there are shear bands formed around their indents and strain bursts occurring during the load-holding process of indentation creep. These results imply that there is a transition of the deformation mechanism in the region where the periodicity is equal to 20 nm. This transition of the deformation mechanism can be ascribed to grain-size-dependent competition between the dislocations-mediated plasticity and grain-boundary sliding-mediated plasticity.

scholarly journals Fracture in Bulk Amorphous Alloys

1998 ◽  
Vol 554 ◽  
Author(s):  
J. A. Horton ◽  
J. L. Wright ◽  
J. H. Schneibel
Keyword(s):  
Crack Propagation ◽  
Crack Growth ◽  
Shear Bands ◽  
Bulk Amorphous Alloy ◽  
In Situ Tem ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Crack Tips ◽  
Temperature Fracture

AbstractThe fracture behavior of a Zr-based bulk amorphous alloy, Zr-10 Al-5 Ti-17.9 Cu-14.6Ni (at.%), was examined by transmission electron microscopy (TEM) and x-ray diffraction forany evidence of crystallization preceding crack propagation. No evidence for crystallizationwas found in shear bands in compression specimens or at the fracture surface in tensile specimens.In- situ TEM deformation experiments were performed to more closely examine actualcrack tip regions. During the in-situ deformation experiment, controlled crack growth occurredto the point where the specimen was approximately 20 μm thick at which point uncontrolledcrack growth occurred. No evidence of any crystallization was found at the crack tips or thecrack flanks. Subsequent scanning microscope examination showed that the uncontrolledcrack growth region exhibited ridges and veins that appeared to have resulted from melting. Performing the deformations, both bulk and in-situ TEM, at liquid nitrogen temperatures (LN2) resulted in an increase in the amount of controlled crack growth. The surface roughness of the bulk regions fractured at LN2 temperatures corresponded with the roughness of the crack propagation observed during the in-situ TEM experiment, suggesting that the smooth-appearing room temperature fracture surfaces may also be a result of localized melting.

Size dependent behavior of Fe3O4crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

2017 ◽  
Vol 19 (31) ◽  
pp. 20867-20880 ◽  
Author(s):  
David C. Bock ◽  
Christopher J. Pelliccione ◽  
Wei Zhang ◽  
Janis Timoshenko ◽  
K. W. Knehr ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Behavior ◽  
X Ray Absorption

Crystal and atomic structural changes of Fe3O4upon electrochemical (de)lithiation were determined.

scholarly journals Enhanced Photocatalytic Activity of Vanadium-Doped SnO2 Nanoparticles in Rhodamine B Degradation

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
H. Letifi ◽  
Y. Litaiem ◽  
D. Dridi ◽  
S. Ammar ◽  
R. Chtourou
Keyword(s):  
Photocatalytic Activity ◽  
Rhodamine B ◽  
Crystal Size ◽  
Sno2 Nanoparticles ◽  
X Ray Diffraction ◽  
Optical Studies ◽  
Vanadium Concentration ◽  
X Ray ◽  
Transmission Electron ◽  
20 Nm

In this paper, we have reported a novel photocatalytic study of vanadium-doped SnO2 nanoparticles (SnO2: V NPs) in rhodamine B degradation. These NPs have been prepared with vanadium concentrations varying from 0% to 4% via the coprecipitation method. Structural, morphological, and optical properties of the prepared nanoparticles have been investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscope (TEM), and UV-Vis and photoluminescence (PL) spectroscopy. Structural properties showed that both undoped and SnO2: V NPs exhibited the tetragonal structure, and the average crystal size has been decreased from 20 nm to 10 nm with the increasing doping level of vanadium. Optical studies showed that the absorption edge of SnO2: V NPs showed a redshift with the increasing vanadium concentration. This redshift leads to the decrease in the optical band gap from 3.25 eV to 2.55 eV. A quenching in luminescence intensity has been observed in SnO2: V NPs, as compared to the undoped sample. Rhodamine B dye (RhB) has been used to study the photocatalytic degradation of all synthesized NPs. As compared to undoped SnO2 NPs, the photocatalytic activity of SnO2: V NPs has been improved. RhB dye was considerably degraded by 95% within 150 min over on the SnO2: V NPs.

scholarly journals Synthesis, Structure, and Luminescent Properties of Europium-Doped Hydroxyapatite Nanocrystalline Powders

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Carmen Steluta Ciobanu ◽  
Simona Liliana Iconaru ◽  
Florian Massuyeau ◽  
Liliana Violeta Constantin ◽  
Adrian Costescu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Textural Properties ◽  
Average Crystallite Size ◽  
Luminescent Properties ◽  
Nanocrystalline Powders ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Vibrational Studies ◽  
20 Nm

The luminescent europium-doped hydroxyapatite (Eu:HAp, Ca10−xEux(PO4)6(OH)2) with0≤x≤0.2nanocrystalline powders was synthesized by coprecipitation. The structural, morphological, and textural properties were well characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The vibrational studies were performed by Fourier transform infrared, Raman, and photoluminescence spectroscopies. The X-ray diffraction analysis revealed that hydroxyapatite is the unique crystalline constituent of all the samples, indicating that Eu has been successfully inserted into the HAp lattice. Eu doping inhibits HAp crystallization, leading to a decrease of the average crystallite size from around 20 nm in the undoped sample to around 7 nm in the sample with the highest Eu concentration. Furthermore, the samples show the characteristic5D0→7F0transition observed at 578 nm related to Eu3+ions distributed on Ca2+sites of the apatitic structure.

Characteristics of nanophase TiAl produced by inert gas condensation

1992 ◽  
Vol 7 (11) ◽  
pp. 2962-2970 ◽  
Author(s):  
H. Chang ◽  
C.J. Altstetter ◽  
R.S. Averback
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Large Fraction ◽  
Inert Gas ◽  
Full Density ◽  
Indentation Creep ◽  
Small Component ◽  
Grain Sizes ◽  
Transmission Electron ◽  
20 Nm

Nanophase TiAl, with grain sizes in the range of 10–20 nm, was synthesized by magnetron sputtering in an inert gas atmosphere and consolidated, in situ, under vacuum. The properties of the powders and sintered compacts were studied by transmission electron microscopy, scanning electron microscopy, calorimetry, Rutherford backscattering, and x-ray diffraction. Samples compacted at 1.0 GPa at room temperature had a large fraction of amorphous phase, while samples compacted at the same pressure and 250 °C were predominantly the equilibrium γ phase. An enthalpy change of 22 kJ/g-atom was measured during a DSC scan over the temperature range 125–450 °C, which is approximately the range over which crystallization occurs. Nearly full density could be achieved by sintering at 450 °C without significant, concomitant grain growth. The Vickers microhardness of these samples at room temperature and at −30 °C revealed an inverse Hall–Petch relationship at small grain sizes, 10–30 nm, and the usual Hall–Petch behavior at larger grain sizes. A small component of indentation creep was also observed. The maximum hardness is 4 times larger than that of a cast TiAl specimen of the same composition. The Vickers hardness was also observed to decrease rapidly with temperature above 200 °C.

Nanoporous Ni and Ni-Cu Fabricated by Dealloying

2009 ◽  
Vol 1228 ◽  
Author(s):  
Masataka Hakamada ◽  
Yasumasa Chino ◽  
Mamoru Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Noble Metals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Difference ◽  
20 Nm ◽  
Good Workability ◽  
Scanning Electron

AbstractMetallic nanoporous architecture can be spontaneously attained by dealloying of a binary alloy. The nanoporous architecture can be often fabricated in noble metals such as Au and Pt. In this study, nanoporous Ni, Ni-Cu are fabricated by dealloying rolled Ni-Mn and Cu-Ni-Mn alloys, respectively. Unlike conventional Raney nickel composed of brittle Ni-Al or Cu-Al intermetallic compounds, the initial alloys had good workability probably because of their fcc crystal structures. After the electrolysis of the alloys in (NH4)2SO4 aqueous solution, nanoporous architectures of Ni and Ni-Cu with pore and ligament sizes of 10–20 nm were confirmed by scanning electron microscopy and transmission electron microscopy. X-ray diffraction analyses suggested that Ni and Cu atoms form a homogeneous solid solution in the Ni-Cu nanoporous architecture. The ligament sizes of nanoporous Ni and Ni-Cu were smaller than that of nanoporous Cu, reflecting the difference between diffusivities of Ni and Cu at solid/electrolyte interface. Ni can reduce the pore and ligament sizes of resulting nanoporous architecture when added to initial Cu-Mn alloys.

Mechanical Stress, Grain-boundary Relaxation, and Oxidation of Sputtered CuNi(Mn) Films

1999 ◽  
Vol 14 (4) ◽  
pp. 1286-1294 ◽  
Author(s):  
W. Brückner ◽  
W. Pitschke ◽  
S. Baunack ◽  
J. Thomas
Keyword(s):  
Grain Boundary ◽  
Microstructural Characterization ◽  
Excess Vacancy ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Boundary Relaxation ◽  
20 Nm ◽  
Atomic Rearrangement

This paper focuses on understanding stress development in CuNi42Mn1 thin films during annealing in Ar. In addition to stress-temperature measurements, resistance-temperature investigations and chemical and microstructural characterization by Auger electron spectroscopy, scanning and transmission electron microscopy, x-ray diffraction, and atomic force microscopy were also carried out. The films are polycrystalline with a grain size of 20 nm up to 450 °C. To explain the stress evolution above 120 °C, atomic rearrangement (excess-vacancy annihilation, grain-boundary relaxation, and shrinkage of grain-boundary voids) and oxidation were considered. Grain-boundary relaxation was found to be the dominating process up to 250–300 °C. A sharp transition from compressive to tensile stress between 300 and 380 °C is explained by the formation of a NiO surface layer due to reaction with the remaining oxygen in the Ar atmosphere. This oxidation is masking the inherent structural relaxation above 300 °C.

Mechanism of Achieving Nanocrystalline AIRu By Ball Milling

1988 ◽  
Vol 132 ◽  
Author(s):  
E. Hellstern ◽  
H. J. Fecht ◽  
C. Garland ◽  
W. L. Johnson ◽  
W. M. Keck
Keyword(s):  
Ball Milling ◽  
Crystal Size ◽  
Shear Bands ◽  
Nanocrystalline Structure ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Energy Ball ◽  
Small Grains

ABSTRACTWe investigated through X- ray diffraction and transmission electron microscopy the crystal refinement of the intermetallic compound AIRu by high- energy ball milling. The deformation process causes a decrease of crystal size to 5–7 rum and an increase of atomic level strain. This deformation is localized in shear bands with a thickness of 0.5 to 1 micron. Within these bands the crystal lattice breaks into small grains with a typical size of 8–14 rum. Further deformation leads to a final nanocrystalline structure with randomly oriented crystallite grains separated by high- angle grain boundaries.

TiO2 Nanoparticles Synthesized with Ti(SO4)2 as Precursor via the Hydrothermal Method and their Optical Absorption Properties

2017 ◽  
Vol 727 ◽  
pp. 280-283
Author(s):  
Xiao Ming Fu
Keyword(s):  
Hydrothermal Method ◽  
Ph Value ◽  
Blue Shift ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
Tem Analysis ◽  
Visible Absorption ◽  
Transmission Electron ◽  
20 Nm

Anatase TiO2 particles of about 20 nm in the diameter were successfully synthesized with Ti (SO4)2 as titanium source and stronger ammonia water as precipitant at 240°C for 48 h with pH=5 using the hydrothermal method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and ultraviolet-visible absorption spectroscopy (UV-VIS). XRD analysis showed that the phase of the samples was anatase TiO2. TEM analysis confirmed that TiO2 particles of about 50 nm in the diameter were obtained when the pH value was 0.12. With the increasement of the pH value, the size of as-prepared TiO2 particles became remarkably fine. However, with the further increase of the pH value, the size of TiO2 particles was not obvious. TiO2 particles of about 20 nm in the diameter were obtained when the pH value was 5. And UV-VIS results showed that the size of anatase TiO2 nanoparticles, which became small, was propitious to the blue shift of their absorption peak.

Grain Size Dependent Magnetic Properties of Nanocrystalline Sm [BE]Co [BD][BJ]/Cu

2001 ◽  
Vol 703 ◽  
Author(s):  
L. Bessais ◽  
C. Djéga-Mariadassou ◽  
J. Zhang ◽  
V. Lalanne ◽  
A. Percheron-Guégan
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Rietveld Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Magnetic Metal ◽  
Chemical Distribution

ABSTRACTThe evolution of both micro structural and magnetic properties of the Sm[BE]Co[BD][BJ] Cu powder, is studied as a function of soft co-milling time. The average grain size in the range 20 - 50 nm was determined by transmission electron microscopy coupled with x-ray diffraction using the Rietveld method. The particle shape and chemical distribution were investigated by elemental mapping, using wavelength dispersive x-ray analysis with electron microprobe analysis. The coercivity evolution shows that an optimum value of 6 kOe is obtained after 5 h co-milling. The microstructure analysis indicates that both materials are well mixed in nanometer scale. This technique appears as a potential route to synthesize nanocrystalline Sm[BE]Co[BD][BJ] isolated by non-magnetic metal Cu.

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