Superior Quality Rails: Structure-Phase States and Defect Substructure

2014 ◽  
Vol 1013 ◽  
pp. 127-132 ◽  
Author(s):  
Victor Gromov ◽  
Alexei Yuriev ◽  
Yurii F. Ivanov ◽  
Konstantin Morozov ◽  
Sergey Konovalov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase State ◽  
Layer By Layer ◽  
Quantitative Parameters ◽  
Defect Substructure ◽  
Transmission Electron ◽  
Layer Analysis ◽  
Structure Phase

Using transmission electron microscopy methods the layer by layer analysis of the bulk hardened superior quality rails is carried out and the quantitative parameters of structure, phase state and defect substructure gradients are established. It is shown that the interface boundaries globular cementite particles-matrix are the possible places of microcracks initiation.

Formation of Fine Structure of Differentially Hardened Rails

2014 ◽  
Vol 682 ◽  
pp. 41-45
Author(s):  
V.E. Gromov ◽  
Yu.F. Ivanov ◽  
K.V. Morozov ◽  
K.V. Alsaraeva
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Substructure ◽  
Diffusion Mechanism ◽  
Compressed Air ◽  
Layer By Layer ◽  
Transmission Electron ◽  
Layer Analysis ◽  
Structure Phase ◽  
Lamellar Pearlite

Differential hardening of rails by compressed air at different regimes is accompanied by formation of morphologically different structure, being formed according to the diffusion mechanism of γ ↔ α transformation and consisting of grains of lamellar pearlite, free ferrite and grains of ferrite-carbide mixture.By methods of transmission electron microscopy the layer by layer analysis of differentially hardened rails has been carried out, the quantitative parameters of the structure, phase composition and dislocation substructure have been established and their comparison has been made for different regimes of hardening. It has been found that the structure-phase states being formed have gradient character, defined by the hardening regime, direction of study from the tread contact surface and by depth of location of layer under study.

Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition

1990 ◽  
Vol 48 (4) ◽  
pp. 686-687
Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
High Energy ◽  
Nucleation Mechanism ◽  
Layer By Layer ◽  
Extended Defect ◽  
Island Formation ◽  
Si Substrates ◽  
Transmission Electron

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.

Growth of TiN/AlN Superlattice by Pulsed Laser Deposition

2002 ◽  
Vol 750 ◽  
Author(s):  
H. Wang ◽  
A. Gupta ◽  
Ashutosh Tiwari ◽  
X. Zhang ◽  
J. Narayan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Pulsed Laser Deposition ◽  
High Speed ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Internal Stresses ◽  
Layer By Layer ◽  
Special Configuration ◽  
Transmission Electron

ABSTRACTTiN-AlN binary-components have attracted a lot of interests in coatings of high speed cutting tools, due to their higher oxidation resistance, higher hardness, lower internal stresses and better adhesion. Especially, nanometer-scale multilayer structures of AlN/TiN show superior structural and mechanical properties due to their tremendous interface area and become one of the promising candidates for superhard coatings. Here we present a novel method to grow highly aligned TiN/AlN superlattice by pulsed laser deposition. In this method TiN and AlN targets are arranged in a special configuration that they can be ablated in sequence, giving alternate layer by layer growth of TiN(1nm)/AlN(4nm). X-ray diffraction and transmission electron microscopy (TEM) analysis showed the structure to be cubic for both TiN and AlN in the nanoscale multilayers. Microstructure and uniformity for the superlattice structure were studied by TEM and Scanning transmission electron microscopy with Z-contrast (STEM). Nanoindentation results indicated a higher hardness for this new structure than pure AlN and rule-of-mixtures value. Four point probe electrical resistivity measurements showed overall insulating behavior.

Cross-sectional Transmission Electron Microscopy of (AlAs)15(InAs)1 Superlattices

1990 ◽  
Vol 48 (4) ◽  
pp. 678-679
Author(s):  
C. Ballesteros ◽  
J. Piqueras ◽  
M. Vázquez ◽  
J.P. Silveira ◽  
L. González ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Layer ◽  
Growth Conditions ◽  
Layer By Layer ◽  
High Quality ◽  
Cross Sectional ◽  
Strained Layer ◽  
Transmission Electron ◽  
Strained Layer Superlattices

Multibeam and bright field transmission electron microscopy are used to determine the structure of (InAs)1/(AlAs)15 superlattices. The interest of InAs/AlAs system arises from the large gap difference. The main problem in the obtention of strained layer superlattices (SLS), with a large lattice mismach, 7% is that of controlling the growth process to obtain high quality layers with sharp interfaces.A modification of the conventional MBE technique, Atomic Layer Molecular Beam Epitaxy (ALMBE) seems to be very appropiate for the growth of such strained layer structures. In particular, high quality layers of materials that demand different growth conditions by MBE, like InAs and AlAs can be obtained at a common low substrate temperature (350-400°) by ALMBE due to the ability to force 2D or layer by layer nucleation and growth. Present superlattices are part of a series with structure (AlAs)15/(InAs)n (n = 1, 2, 3 and 5 ml) whose study by HREM is under way in order to determine critical thickness limits.

High resolution transmission electron microscopy study of interface structures and growth defects in epitaxial Bi2Sr2Can−1CunO4+2n + δ films on SrTiO3 and LaAlO3

1996 ◽  
Vol 11 (10) ◽  
pp. 2416-2428 ◽  
Author(s):  
N. D. Zakharov ◽  
D. Hesse ◽  
J. Auge ◽  
H. G. Roskos ◽  
H. Kurz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Layer By Layer ◽  
Composite Target ◽  
Substrate Interface ◽  
Dc Sputtering ◽  
Transmission Electron ◽  
Interfacial Dislocations ◽  
Film Substrate

The defect structure of epitaxial, c-oriented Bi2Sr2Can−1CunO4+2n+δ (BSCCO) thin films grown by dc-sputtering and layer-by-layer MBE on SrTiO3 and LaAlO3 single crystal substrates was investigated by high-resolution transmission electron microscopy (HRTEM). Particular emphasis was put on the structure of the film/substrate interface. The films grown by dc-sputtering show a rather perfect structure involving a regular stacking of the unit cells. In spite of this regularity, there are many defects, such as twins, chemical stacking faults, and precipitates, as well as interfacial dislocations accommodating the film/substrate lattice misfit. The MBE-grown films contain twins and interfacial dislocations, but most prominent are precipitates of various size and rather high number density. Composition and structure of the precipitates were analyzed. Interfacial dislocations were found to be located in the films at a distance of up to 3 nm from the film/substrate interface. The experiments showed that the quality of the film/substrate interface in MBE-grown films is considerably higher with respect to smoothness, sharpness, and regularity, if the layer-by-layer MBE process starts with a Sr–O layer instead of a Bi–O layer. This observation is in correspondence to the observed interface structure of the dc-sputtered films, where the first film layer was a Sr–O layer, not a Bi–O layer, in spite of the films being sputtered from a composite target. A structure model of the Bi2Sr2Can−1CunO4+2n+δ/(100)SrTiO3 interface is proposed. The prolonged MBE process was shown to imply a chemical interaction between the SrTiO3 substrate and the growing film, resulting in the formation of Sr-rich phases in the near-interface substrate regions.

scholarly journals Transmission electron microscopy analysis of the interfaces of TiAlN/Mo multilayers

2008 ◽  
Vol 14 (S3) ◽  
pp. 1-4 ◽  
Author(s):  
C.J. Tavares ◽  
L. Rebouta ◽  
J.P. Rivière ◽  
M.F. Denanot
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cross Sections ◽  
Structural Disorder ◽  
Layer Growth ◽  
Layer By Layer ◽  
Transmission Electron Microscopy Analysis ◽  
Transmission Electron ◽  
Electron Microscopy Analysis ◽  
Chemical Modulation

This paper focus on the analysis of the interfaces of nanocomposite TiAlN/Mo multilayers by high-resolution transmission electron microscopy (HRTEM). These thin films were deposited by reactive magnetron sputtering, with modulation periods below 7 nm. The structural disorder at the interfaces was probed by the analysis of the X-ray diffraction data, and afterwards correlated with the TEM observations on the cross-sections of the TiAlN/Mo multilayers. For specific deposition conditions, these structures can be prepared with relatively planar interfaces, revealing layer-by-layer growth. For modulation periods below 3 nm the intermixing acts a major role in the degradation of the multilayer chemical modulation.

scholarly journals Scanning Transmission Electron Microscopy (STEM) Tomography of Layer-by-Layer PAH/PSS-Au Nanocomposite Structures

2011 ◽  
Vol 17 (S2) ◽  
pp. 1012-1013 ◽  
Author(s):  
N Bassim ◽  
A Herzing ◽  
W Dressick ◽  
K Wahl ◽  
D Petrovykh ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Layer By Layer ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Nanocomposite Structures ◽  
Stem Tomography

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

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