scholarly journals A study on the effect of nano-precipitates on fracture behavior of nano-structured Al-2wt%Cu alloy fabricated by accumulative roll bonding (ARB) process

2016 ◽  
Vol 52 (1) ◽  
pp. 93-98 ◽  
Author(s):  
B. Azad ◽  
E. Borhani
Keyword(s):  
Electron Microscope ◽  
Accumulative Roll Bonding ◽  
Average Particle Size ◽  
Void Coalescence ◽  
Average Particle ◽  
Roll Bonding ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Mean Grain Size ◽  
Average Size

An Al-2wt%Cu alloy was subjected to accumulative roll bonding (ARB) process up to a strain of 4.8. The two kinds of different microstructures, i.e, solution treated (ST) one and 190?C pre-aged for 30 min (Aged), were prepared as the starting structures for the ARB process. The microstructures were studied by transmission electron microscope (TEM) and electron backscattering diffraction (EBSD). The results showed that the fine precipitates having the average particle size of 16 nm were formed after aging process. On the other hand, the mean grain size of the ST-ARB and the Aged-ARB specimens reached to 650 nm and 420 nm, respectively. Study of the fracture surfaces were carried out by scanning electron microscope (SEM). The results indicated that at 0-cycle ARB, the specimens show dimples indicating the micro-void coalescence (MVC) mechanism of ductile fracture. The average size of dimples was larger in the ST-ARB specimen compared to the Aged-ARB specimen. The fracture mode was transgranular cleavage fracture in the Aged-specimen. At 3- cycle and 6-cycle ARB, also the specimens showed cleavage facets and river lines, that the river lines or the stress lines are steps between cleavage or parallel planes, which are always converged in the direction of local crack propagation.

Preparation of Cr2O3 Nanoparticles via Hydrothermal Reduction of CH3OH

2012 ◽  
Vol 463-464 ◽  
pp. 760-763
Author(s):  
Zhen Zhao Pei ◽  
Hong Bin Xu ◽  
Yi Zhang
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Average Particle Size ◽  
Average Particle ◽  
Calcination Temperatures ◽  
Cr2o3 Nanoparticles ◽  
Average Size ◽  
Hydrothermal Reduction ◽  
Scanning Electron

Nanoparticles of Cr2O3 were successfully obtained via hydrothermal reduction of CH3OH. The oxidant and chromium source was CrO3. The process needs no stirrer or surfactant and the CrO3 concentration was 0.83mol/L. The obtained products were loosely agglomerated Cr2O3 nanoparticles with the average size of 29 to 79 nm. Influences of reactant ratios and calcination temperatures on the specific surface area and average particle size were discussed. And the morphology of nanoparticles was investigated by use of field-emission scanning electron microscope.

Preparation of an Amphiphilic Magnetic Copolymer Microspheres

2014 ◽  
Vol 881-883 ◽  
pp. 846-849
Author(s):  
Zai Man Liu ◽  
Yun Liu ◽  
Peng Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Average Particle Size ◽  
Water Soluble ◽  
Magnetic Microspheres ◽  
Average Particle ◽  
Water Medium ◽  
Vibrating Sample Magnetometer ◽  
Transmission Electron ◽  
Average Size

The magnetic polymer microspheres were synthesized by copolymerization of styrene with a water-soluble polyurethane macromonomer in the presence of Fe3O4in ethanol/water medium. The structure of copolymer was determined by FTIR spectroscopy. The morphology and the average size of magnetic microspheres were characterized by transmission electron microscopy. The magnetic properties were recorded with a vibrating sample magnetometer. The results show that the magnetic microspheres had an average particle size of 500nm. The magnetic microspheres have super paramagnetic, enhanced hydrophilicity and the characteristics of simple and rapid magnetic separation. The magnetic susceptibility was 3.898×10-5emu/(Oe·g) and the saturation magnetization was 41.122 emu/g.

scholarly journals Study of Optical Constants of ZnO Dispersed PC/PMMA Blend Nanocomposites

2016 ◽  
Vol 3 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Shalini Agarwal ◽  
Y. K. Saraswat ◽  
Vibhav K. Saraswat
Keyword(s):  
Refractive Index ◽  
Band Gap ◽  
Optical Constants ◽  
Average Particle Size ◽  
Research Work ◽  
Average Particle ◽  
Chemical Route ◽  
Transmission Electron ◽  
Average Size ◽  
Blend Nanocomposites

Present research work deals with the optical study of Zinc Oxide (ZnO) dispersed Polycarbonate/Polymethylmethacrylate (PC/PMMA) blend nanocomposites. ZnO nanoparticles have been prepared by simple chemical route and their average size has been confirmed by Transmission Electron Microscopy (TEM). The average particle size of the nanoparticles has been found to be ~11 nm. Formation of PC/PMMA blend nanocomposites has been confirmed by means of X-ray Diffraction (XRD). Absorption spectra, recorded using UV-Visible spectrophotometer, have been used to determine optical constants such as band gap, extinction coefficient, refractive index and real & imaginary part of dielectric constant. It has been found that band gap decreases as ZnO wt% increases in the blend nanocomposites. Lowest band gap has been found for PC25%/PMMA75% with ZnO 3 wt% blend nanocomposite. Increase in refractive index has also been found with increasing ZnO content. These types of blend nanocomposites have applications in UV-shielding and wave guide technologies.

SYNTHESIS, CHARACTERIZATION, AND OPTICAL PROPERTIES OF Y-DOPED ZnO NANOPARTICLES

NANO ◽  
2009 ◽  
Vol 04 (04) ◽  
pp. 225-232 ◽  
Author(s):  
TALAAT M. HAMMAD ◽  
JAMIL K. SALEM ◽  
ROGER G. HARRISON
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Zno Nanoparticles ◽  
Average Particle Size ◽  
Precipitation Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Doped Zno ◽  
Size And Morphology

Zinc oxide ( ZnO ) and yttrium-doped ZnO nanoparticles with particle size in the nanometer range have been successfully synthesized by the alkali precipitation method. The nanoparticle size and morphology have been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). The average particle size of Y-doped ZnO nanoparticles is about 17–29 nm. The absorption and photoluminescence (PL) spectra of the undoped and doped ZnO nanoparticles were also investigated. The optical band gap of ZnO nanoparticles can be tuned from 3.27 to 3.40 eV with increasing yittrium doping levels from 0 to 5%. The nanoparticles gave two emission peaks, one at around 376 nm and the other at 500 nm.

Influence of Stacking Fault Energy on the Grain Size of FCC Metals Fabricated by Accumulative Roll Bonding Process

2014 ◽  
Vol 1064 ◽  
pp. 131-137
Author(s):  
Roohollah Jamaati ◽  
Mohammad Reza Toroghinejad
Keyword(s):  
Grain Size ◽  
Accumulative Roll Bonding ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Roll Bonding ◽  
Transmission Electron ◽  
Mean Grain Size ◽  
Mean Size ◽  
The Mean ◽  
Evolution Of Microstructure

In this study, the effect of stacking fault energy on the grain size of aluminum, copper, and brass fabricated via accumulative roll bonding (ARB) process was investigated. Evolution of microstructure of the samples was investigated by transmission electron microscopy (TEM). It was found that occurrence of the recrystallization (both continuous and discontinuous) in the copper and brass led to the formation of nanograins with mean size of 80, and 40 nm, respectively; while, the mean grain size of aluminum was 250 nm. Differences in microstructural evolution during processing of aluminum, copper, and brass was related to their stacking fault energies (SFEs). When the SFE decreased, grain refinement occurred more easily and the measured grain size was smaller.

Deviations from Ideal Decagonal Symmetry in Electron Diffraction Patterns of the “Decagonal” Phase in the Al-Co-Cu Alloy System

1991 ◽  
Vol 49 ◽  
pp. 914-915
Author(s):  
Atul S. Ramani ◽  
Earle R. Ryba ◽  
Paul R. Howell
Keyword(s):  
Electron Microscope ◽  
Alloy System ◽  
Nominal Composition ◽  
Dimensional Lattice ◽  
3 Dimensional ◽  
Decagonal Phase ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Lattice Periodicity ◽  
Diffraction Patterns

The “decagonal” phase in the Al-Co-Cu system of nominal composition Al65CO15Cu20 first discovered by He et al. is especially suitable as a topic of investigation since it has been claimed that it is thermodynamically stable and is reported to be periodic in the dimension perpendicular to the plane of quasiperiodic 10-fold symmetry. It can thus be expected that it is an important link between fully periodic and fully quasiperiodic phases. In the present paper, we report important findings of our transmission electron microscope (TEM) study that concern deviations from ideal decagonal symmetry of selected area diffraction patterns (SADPs) obtained from several “decagonal” phase crystals and also observation of a lattice of main reflections on the 10-fold and 2-fold SADPs that implies complete 3-dimensional lattice periodicity and the fundamentally incommensurate nature of the “decagonal” phase. We also present diffraction evidence for a new transition phase that can be classified as being one-dimensionally quasiperiodic if the lattice of main reflections is ignored.

Microstructure Characterization of Ag Nanoparticles Prepared by Hydrothermal Method

2012 ◽  
Vol 476-478 ◽  
pp. 1138-1141
Author(s):  
Zhi Qiang Wei ◽  
Qiang Wei ◽  
Li Gang Liu ◽  
Hua Yang ◽  
Xiao Juan Wu
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Hydrothermal Method ◽  
Ag Nanoparticles ◽  
Average Particle Size ◽  
Average Particle ◽  
Face Centered Cubic ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Face Centered

Ag nanoparticles were successfully synthesized by hydrothermal method under the polyol system combined with traces of sodium chloride, Silver nitrate(AgNO3) and polyvinylpyrrolidone (PVP) acted as the silver source and dispersant respectively. The samples by this process were characterized via X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption equation, transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED) to determine the chemical composition, particle size, crystal structure and morphology. The experiment results indicate that the crystal structure of the samples is face centered cubic (FCC) structure as same as the bulk materials, The specific surface area is 24 m2/g, the particle size distribution ranging from10 to 50 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results.

Synthesis and Characterization of Water-Soluble Monolayer-Protected Gold Nanoparticles

2011 ◽  
Vol 415-417 ◽  
pp. 617-620 ◽  
Author(s):  
Yan Su ◽  
Ying Yun Lin ◽  
Yu Li Fu ◽  
Fan Qian ◽  
Xiu Pei Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Gold Nanoparticles ◽  
Average Particle Size ◽  
Water Soluble ◽  
Synthesis And Characterization ◽  
Average Particle ◽  
Transmission Electron

Water-soluble gold nanoparticles (AuNPs) were prepared using 2-mercapto-4-methyl-5- thiazoleacetic acid (MMTA) as a stabilizing agent and sodium borohydride (NaBH4) as a reducing agent. The AuNPs product was analyzed by transmission electron microscopy (TEM), UV-vis absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR). The TEM image shows that the particles were well-dispersed and their average particle size is about 5 nm. The UV-vis absorption and FTIR spectra confirm that the MMTA-AuNPs was stabilized by the carboxylate ions present on the surface of the AuNPs.

scholarly journals Preparation of Polyetherimide Nanoparticles by a Droplet Evaporation-Assisted Thermally Induced Phase-Separation Method

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1548
Author(s):  
Peng Zhu ◽  
Huapeng Zhang ◽  
Hongwei Lu
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Phase Separation ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Droplet Evaporation ◽  
Average Particle ◽  
Thermally Induced Phase Separation ◽  
Thermally Induced ◽  
Pei Nanoparticles

The droplet evaporation effect on the preparation of polyetherimide (PEI) nanoparticles by thermally induced phase separation (TIPS) was studied. PEI nanoparticles were prepared in two routes. In route I, the droplet evaporation process was carried out after TIPS. In route II, the droplet evaporation and TIPS processes were carried out simultaneously. The surface tension and shape parameters of samples were measured via a drop shape analyzer. The Z-average particle diameter of PEI nanoparticles in the PEI/dimethyl sulfoxide solution (DMSO) suspension at different time points was tested by dynamic light scattering, the data from which was used to determine the TIPS time of the PEI/DMSO solution. The natural properties of the products from both routes were studied by optical microscope, scanning electron microscope and transmission electron microscope. The results show that PEI nanoparticles prepared from route II are much smaller and more uniform than that prepared from route I. Circulation flows in the droplet evaporation were indirectly proved to suppress the growth of particles. At 30 °C, PEI solid nanoparticles with 193 nm average particle size, good uniformity, good separation and good roundness were obtained. Route I is less sensitive to temperature than route II. Samples in route I were still the accumulations of micro and nanoparticles until 40 °C instead of 30 °C in route II, although the particle size distribution was not uniform. In addition, a film structure would appear instead of particles when the evaporation temperature exceeds a certain value in both routes. This work will contribute to the preparation of polymer nanoparticles with small and uniform particle size by TIPS process from preformed polymers.

Study on the synthesis of antibacterial plastic by using silver nanoparticles doped in zeolite framework

2021 ◽  
Vol 6 (1) ◽  
pp. 32-36
Author(s):  
Anh Quoc Le ◽  
Van Phu Dang ◽  
Ngoc Duy Nguyen ◽  
Kim Lan Nguyen Thi ◽  
Kim Lang Vo Thi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Silver Nanoparticles ◽  
Average Particle Size ◽  
Bactericidal Effect ◽  
Ethanol Solution ◽  
Average Particle ◽  
Γ Irradiation ◽  
Zeolite Framework ◽  
Ion Exchange Reaction ◽  
Transmission Electron

Silver nanoparticles (AgNPs) doped in the zeolite framework (AgNPs/Z) were successfully synthesized by γ-irradiation in ethanol solution of silver ion-zeolite (Ag+/Z) prepared by ion exchange reaction between silver nitrate (AgNO3) and zeolite 4A. The effects of the Ag+ concentration and irradiation dose on the formation of AgNPs/Z were also investigated. AgNPs/Z with the silver content of about 10,000 ppm and the average particle size of AgNPs of about 27 nm was characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM). Firstly, AgNPs/Z was added into PP resins for creation of PP-AgNPs/Z masterbatch (Ag content of ~10.000 ppm) and then PP-AgNPs/Z plastics were preapared by mixing masterbatch with PP resins. The antibacterial activity of the PP-AgNPs/Z plastics was investigated against Gram-negative bacteria Escherichia coli (E. coli). The results showed that PP-AgNPs/Z plastic contained 100 ppm of Ag possessed a high antibacterial property, namely the bactericidal effect was more than 96 % on the platic surface. In conclusion, possessing many advantages such as: vigorously antibacterial effect and good dispersion in plastic matrix, AgNPs/Z is promising to be applied as bactericidal agent for plastic industry.

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