Microstructure Origin for Thermal Fatigue of TiNi Films

2001 ◽  
Vol 672 ◽  
Author(s):  
Shulin Wen ◽  
Jibao He
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thermal Fatigue ◽  
Microstructure Change ◽  
Fatigue Specimen ◽  
Niti Sma ◽  
Transmission Electron ◽  
Alloy Material ◽  
Before And After ◽  
20 Nm

ABSTRACTIn order to improve the performance and prolong the life of shape memory alloy material (SMA), it is very important to trace and study the microstructure change on the fatigue of SMA. The microstructure features between the samples before and after thermal fatigue (about 100,000 thermal cycles) of the NiTi-SMA films were examined and compared with each other by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). It was found that there is no difference of microstructures between the two kinds of samples except some precipitates appeared in the fatigue specimen. These precipitates which may be identified as TiNi3 phase with a grain size of 10-20 nm may impede transformation from martensite to austenite which works as mechanism of SMA during thermal fatigue. Therefore, these precipitates result in the serious decay on SMA performance and further fracture of the SMA material.

Mechanisms of misfit strain relaxation in epitaxially grown BLT (Bi4-xLaxTi3O12, x = 0.75) thin films

2003 ◽  
Vol 779 ◽  
Author(s):  
Hyung Seok Kim ◽  
Sang Ho Oh ◽  
Ju Hyung Suh ◽  
Chan Gyung Park
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Strain Relaxation ◽  
Lattice Misfit ◽  
Misfit Strain ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
20 Nm

AbstractMechanisms of misfit strain relaxation in epitaxially grown Bi4-xLaxTi3O12 (BLT) thin films deposited on SrTiO3 (STO) and LaAlO3 (LAO) substrates have been investigated by means of transmission electron microscopy (TEM). The misfit strain of 20 nm thick BLT films grown on STO substrate was relaxed by forming misfit dislocations at the interface. However, cracks were observed in 100 nm thick BLT films grown on the same STO. It was confirmed that cracks were formed because of high misfit strain accumulated with increasing the thickness of BLT, that was not sufficiently relaxed by misfit dislocations. In the case of the BLT film grown on LAO substrate, the magnitude of lattice misfit between BLT and LAO was very small (~1/10) in comparison with the case of the BLT grown on STO. The relatively small misfit strain formed in layered structure of the BLT films on LAO, therefore, was easily relaxed by distorting the film, rather than forming misfit dislocations or cracks, resulting in misorientation regions in the BLT film.

scholarly journals Endothelium-derived hyperpolarizing factor in preeclampsia: heterogeneous contribution, mechanisms, and morphological prerequisites

2008 ◽  
Vol 294 (2) ◽  
pp. R510-R519 ◽  
Author(s):  
Leanid Luksha ◽  
Henry Nisell ◽  
Natallia Luksha ◽  
Marius Kublickas ◽  
Kjell Hultenby ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Subcutaneous Fat ◽  
Normal Pregnancy ◽  
Transmission Electron ◽  
Main Pathway ◽  
Before And After ◽  
Group 2 ◽  
Cytochrome P 450 ◽  
Group 1

We hypothesized that in preeclampsia (PE), contribution of endothelium-derived hyperpolarizing factor (EDHF) and the mechanism/s of its action differ from that in normal pregnancy (NP). We aimed to assess endothelial function and morphology in arteries from NP and PE with particular focus on EDHF. Arteries (≈200 μm) were dissected from subcutaneous fat biopsies obtained from women undergoing cesarean section. With the use of wire myography, responses to the endothelium-dependent agonist bradykinin (BK) were determined before and after inhibition of pathways relevant to EDHF activity. The overall responses to BK in arteries from PE ( n = 13) and NP ( n = 17) were similar. However, in PE, EDHF-mediated relaxation was reduced ( P < 0.05). All women within the PE group were divided into two subgroups: with more ( group 1) or less ( group 2) than 50% reduction of EDHF-typed responses after 18-α-glycyrrhetinic acid (an inhibitor of myoendothelial gap junctions, MEGJs). The division showed that 1) MEGJs are principally involved when the EDHF contribution is reduced; and 2) when the EDHF contribution is similar to that in NP, the H2O2 and/or cytochrome P-450 epoxygenase products of arachidonic acid (AA), along with MEGJs, confer EDHF-mediated relaxation. In contrast, MEGJs were the main pathway for EDHF in NP. The abundant presence of MEGJs in arteries from NP but deficiency of them in PE was observed using transmission electron microscopy. We conclude that PE is associated with heterogeneous contribution of EDHF, and the mechanism behind EDHF-typed responses is mediated either by MEGJs alone or in combination with H2O2 or cytochrome P-450 epoxygenase metabolites of AA.

Self-Healing and Self-Organized Gold Nanoparticle Films at a Water/Organic Solvent Interface

2006 ◽  
Vol 6 (1) ◽  
pp. 130-134 ◽  
Author(s):  
Olivier Balmes ◽  
Jan-Olov Bovin ◽  
Jan-Olle Malm
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Organic Solvent ◽  
Continuous Production ◽  
Self Healing ◽  
Self Organized ◽  
Transmission Electron ◽  
20 Nm

Gold nanoparticles (5 nm and 20 nm) have been synthesized and stabilized with mercaptoundecanol. These particles, although insoluble in water or common organic solvents, spread as a thin film at the liquid–liquid interface between a water phase and an organic phase. Films of these gold nanoparticles have been observed both by conventional transmission electron microscopy of deposited samples and by cryo-transmission electron microscopy of plunge-frozen samples. The film can be monolayered and extend over centimeter-sized areas. The particle films spontaneously re-assemble and self-organize at the interface when disrupted. This self-healing capacity of the film should make it possible to build a device for continuous production and deposition of the film.

scholarly journals Effect of He-appm/DPA ratio on the damage microstructure of tungsten

MRS Advances ◽  
2016 ◽  
Vol 1 (42) ◽  
pp. 2893-2899 ◽  
Author(s):  
R.W. Harrison ◽  
H. Amari ◽  
G. Greaves ◽  
J.A. Hinks ◽  
S.E. Donnelly
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
Dislocation Loops ◽  
Vacancy Clusters ◽  
Transmission Electron ◽  
Damage Structure ◽  
Ordered Array ◽  
20 Nm

AbstractIn-situ ion irradiation and transmission electron microscopy has been used to examine the effects of the He appm to DPA ratio, temperature and dose on the damage structure of tungsten (W). Irradiations were performed with 15 or 60 keV He+ ions, achieving He-appm/displacements per atom (DPA) ratios of ∼40,000 and ∼2000, respectively, at temperatures between 500 and 1000°C to a dose of ∼3 DPA. A high number of small dislocation loops with sizes around 5–20 nm and a He bubble lattice were observed for both He-appm/DPA ratios at 500°C with a bubble size ∼1.5 nm. Using the g.b=0 criterion the loops were characterised as b = ±1/2<111> type. At 750°C bubbles do not form an ordered array and are larger in size compared to the irradiations at 500°C, with a diameter of ∼3 nm. Fewer dislocation loops were observed at this temperature and were also characterised to be b = ±1/2<111> type. At 1000°C, no dislocation loops were observed and bubbles grew as a function of fluence attributed to vacancy mobility being higher and vacancy clusters becoming mobile.

Synthesis of Icosahedral Boron Arsenide Nanowires for Betavoltaic Applications

2012 ◽  
Vol 1439 ◽  
pp. 69-75 ◽  
Author(s):  
Clint D. Frye ◽  
J.H. Edgar ◽  
Yi Zhang ◽  
Kevin Cooper ◽  
Luke O. Nyakiti ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Nickel Powder ◽  
Wide Band ◽  
High Energy ◽  
Nickel Film ◽  
Transmission Electron ◽  
Platinum Particles ◽  
Boron Arsenide ◽  
20 Nm

ABSTRACTWith a wide band gap of greater than 3.0 eV and the ability to self-heal from radiation damage, icosahedral boron arsenide (B12As2) is an apt candidate for use in next-generation betavoltaics. By capturing and converting high energy electrons from radioisotopes into usable electricity, “nuclear batteries” made from B12As2 could potentially power devices for decades. Compared to bulk crystals or epitaxial films, B12As2 nanowires may have lower defect densities or may even be defect-free, leading to better electrical properties and device performance. In our study, B12As2 nanowires were synthesized via vapor-liquid-solid (VLS) growth using platinum powder and nickel powder on silicon carbide and 20 nm thick nickel film on silicon substrates from 700 °C to 1200 °C. Platinum yielded the highest quality nanowires from 900 °C to 950 °C, resulting in platinum particles densely covered with wires formed by straight segments connected by sharp angular kinks. At these growth temperatures, diameters ranged from less than 30 nm to about 300 nm as determined by scanning electron microscopy and transmission electron microscopy. Growth temperatures of 850 °C or less produced curled wires 200-1000 nm in diameter. Transmission electron microscopy and selected area electron diffraction revealed excellent crystallinity in wires grown above 850 °C, while wires grown at or below 850 °C were partially amorphous. Wires grown from the 20 nm nickel film displayed similar morphologies at temperatures up to 850 °C; from 900 °C to 950 °C, straight, isolated wires were grown with diameters of 200-400 nm. Nickel powder only produced wires larger than 1 μm in diameter. The comparative quality and growth of B12As2nanowires will be discussed.

Synthesis of ZnO2 Nanocrystals Produced by Hydrothermal Process

2009 ◽  
Vol 1242 ◽  
Author(s):  
R. Esparza ◽  
A. Aguilar ◽  
A. Escobedo-Morales ◽  
C. Patiño-Carachure ◽  
U. Pal ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Peroxide ◽  
Transmission Electron Microscopy ◽  
Hydrothermal Process ◽  
High Resolution Electron Microscopy ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Zinc Peroxide ◽  
20 Nm

ABSTRACTZinc peroxide (ZnO2) nanocrystals were directly produced by hydrothermal process. The nanocrystals were synthesized using zinc acetate as precursor and hydrogen peroxide as oxidant agent. The ZnO2 powders were characterized by X-ray powder diffraction and transmission electron microscopy. The results of transmission electron microscopy indicated that the ZnO2powders consisted of nanocrystals with diameters below to 20 nm and a faceted morphology. High resolution electron microscopy observations have been used in order to the structural characterization. ZnO2 nanocrystals exhibit a well-crystallized structure.

Characterization of pulsed laser deposited PbO/MoS2 by transmission electron microscopy

1994 ◽  
Vol 9 (1) ◽  
pp. 236-245 ◽  
Author(s):  
S.D. Walck ◽  
M.S. Donley ◽  
J.S. Zabinski ◽  
V.J. Dyhouse
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sodium Chloride ◽  
Room Temperature ◽  
Film Growth ◽  
Composite Films ◽  
Pulsed Laser ◽  
Two Phase ◽  
Transmission Electron ◽  
20 Nm

Films of PbO/MoS2, grown by pulsed laser deposition, exhibit a significant improvement in tribological performance compared to MoS2 films grown by the same process. The microstructure and crystallography of PbO/MoS2 composite films were investigated using transmission electron microscopy (TEM) to identify the features responsible for this tribological improvement. Self-supporting samples were prepared from pulsed laser deposited, PbO/MoS2 thin films grown on single crystal sodium chloride substrates. Films deposited at room temperature exhibited a two-phase microstructure with one of the phases being amorphous. X-ray microanalysis results showed that the crystalline phase had significantly higher concentration ratios of Mo/Pb, Mo/S, and Pb/S than did the amorphous phase. Films grown at 300 °C were polycrystalline, with a grain size of about 20 nm, and had a NaCl type structure which was isomorphous to PbS. The grains had rectangular shape, and exhibited preferred orientation with the sodium chloride substrate. The concentration of S for these films was approximately 80% of the S concentration for films grown at room temperature. Both the high temperature and room temperature films had S concentrations which were higher than expected from the MoS2 in the target; this was attributed to gettering of the S in the vacuum chamber by Pb. The electron diffraction results, together with previously published results, suggest that the crystal structure of the phases in these films is not responsible for the improvement in tribological properties. However, the microstructural components formed during film growth do determine the wear-induced chemical reaction pathways.

Sub-Micrometer Spatially Resolved Measurements of Mechanical Properties and Correlation to Microstructure and Composition

2000 ◽  
Vol 649 ◽  
Author(s):  
M. Kunert ◽  
B. Baretzky ◽  
S. P. Baker ◽  
E. J. Mittemeijer
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Measurement Techniques ◽  
Spatially Resolved ◽  
Transmission Electron ◽  
20 Nm ◽  
Almost Continuous

ABSTRACTThe variations of hardness, composition, and microstructure within a carbon implanted region – about 350 nm thick – of a Ti-6Al-4V alloy were measured using nanoindentation, Auger electron spectroscopy and transmission electron microscopy, respectively. Correlations among hardness, composition, and microstructure were made with a spatial resolution of about ±20 nm. The variation in hardness within the implanted regions was quantitatively explained as due to the formation of an almost continuous TiC layer and precipitate hardening. The problems that may arise in measuring and correlating spatial variations in such a complex material on this scale are outlined and a successful method to solve them is proposed. The need for highly spatially resolved measurement techniques is emphasized.

Uranium Fixation During Uranium Migration Under an Oxidizing Condition

1994 ◽  
Vol 353 ◽  
Author(s):  
Takashi Murakami ◽  
Katsuyuki Tsuzuki ◽  
Tsutomu Sato ◽  
Hiroshi Isobe ◽  
Toshihiko Ohnuki
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Rock Specimen ◽  
Uranium Mineral ◽  
Ore Deposit ◽  
Iron Minerals ◽  
Transmission Electron ◽  
Uranium Migration ◽  
20 Nm

AbstractA rock specimen, collected downstream of the Koongarra uranium ore deposit, Australia, was examined mainly by high resolution transmission electron microscopy in order to understand the uranium fixation mechanism. Uranium was found to exist as saleeite (Mg(UO2)2(PO4)2.10H2O) microcrystals of 1 – 20 nm scattered between iron minerals (mainly goethite and hematite) of 2 – 50 nm. The microtextural relationship between saléeite and the iron minerals revealed that the iron minerals function as catalyst for the formation of saléeite. The intermediate metamict microstructures of the saléeite microcrystals are consistent with the estimated formation age of saléeite, 1 to 3 × 106 years. Uranium has been, thus, fixed as saléeite downstream as well as in the secondary ore deposit. Saléeite in the secondary ore deposit showed completely periodic to fully metamict microstructures, suggesting that saléeite, a major uranium mineral in the secondary ore deposit, probably began to form a few million years ago and continued to form for the next million years.

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