Compression Deformation Structures of Single Crystal TiAl

1988 ◽  
Vol 133 ◽  
Author(s):  
B. Y. Huang ◽  
B. F. Oliver ◽  
W. C. Oliver
Keyword(s):  
Electron Microscopy ◽  
Plastic Deformation ◽  
Deformation Behavior ◽  
Growth Direction ◽  
Mirror Plane ◽  
Low Density ◽  
Deformation Structures ◽  
Compression Deformation ◽  
Transmission Electron ◽  
Unit Triangle

ABSTRACTThe compression deformation behavior of single crystalline TiAl was examined by transmission electron microscopy (T.E.M.). The relatively pure Ti–56 a/o Al crystal was containerless processed in ultrapure hydrogen. The crystal growth direction is 18° off (011) and 60° off [111] in the [011]– [111]-[010] unit triangle. At low stresses, a/2 [110] type dislocations were observed. a/2 [110] dislocations appeared at slightly higher stresses. Additional plastic deformation initiates twinning. Twinning plays an important role at higher stresses. Diffraction results indicate that most of the twins have the (111) mirror plane.A small amount of (111) twins were also observed. Superdislocations of the a<011> type were not observed to contribute to the plastic deformation in this crystal. The results indicate that plastic deformation by twinning follows the low density of ordinary dislocations.

Investigations on Microstructure Evolution and Deformation Behavior of Aged and Ultrafine Grained Al-Zn-Mg Alloy Subjected to Severe Plastic Deformation

2010 ◽  
Vol 667-669 ◽  
pp. 253-258
Author(s):  
Wei Ping Hu ◽  
Si Yuan Zhang ◽  
Xiao Yu He ◽  
Zhen Yang Liu ◽  
Rolf Berghammer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
Microstructure Evolution ◽  
Deformation Behavior ◽  
Deformation Mechanisms ◽  
Mg Alloy ◽  
Ultrafine Grained

An aged Al-5Zn-1.6Mg alloy with fine η' precipitates was grain refined to ~100 nm grain size by severe plastic deformation (SPD). Microstructure evolution during SPD and mechanical behaviour after SPD of the alloy were characterized by electron microscopy and tensile, compression as well as nanoindentation tests. The influence of η' precipitates on microstructure and mechanical properties of ultrafine grained Al-Zn-Mg alloy is discussed with respect to their effect on dislocation configurations and deformation mechanisms during processing of the alloy.

Control of Morphology and Growth Direction of Gallium Nitride Nanostructures

2003 ◽  
Vol 789 ◽  
Author(s):  
Seung Yong Bae ◽  
Hee Won Seo ◽  
Jeunghee Park
Keyword(s):  
Electron Microscopy ◽  
Gallium Nitride ◽  
Large Scale ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Chemical Vapor Deposition Method ◽  
X Ray Diffraction ◽  
Oxide Mixture ◽  
Temperature Range ◽  
Transmission Electron

ABSTRACTVarious shaped single-crystalline gallium nitride (GaN) nanostructures were produced by chemical vapor deposition method in the temperature range of 900–1200 °C. Scanning electron microscopy, transmission electron microscopy, electron diffraction, x-ray diffraction, electron energy loss spectroscopy, Raman spectroscopy, and photoluminescence were used to investigate the structural and optical properties of the GaN nanostructures. We controlled the GaN nanostructures by the catalyst and temperature. The cylindrical and triangular shaped nanowires were synthesized using iron and gold nanoparticles as catalysts, respectively, in the temperature range of 900 – 1000 °C. We synthesized the nanobelts, nanosaws, and porous nanowires using gallium source/ boron oxide mixture. When the temperature of source was 1100 °C, the nanobelts having a triangle tip were grown. At the temperature higher up to 1200 °C the nanosaws and porous nanowires were formed with a large scale. The cylindrical nanowires have random growth direction, while the triangular nanowires have uniform growth direction [010]. The growth direction of the nanobelts is perpendicular to the [010]. Interestingly, the nanosaws and porous nanowires exhibit the same growth direction [011]. The shift of Raman, XRD, and PL bands from those of bulk was correlated with the strains of the GaN nanostructures.

Microstructures and Growth Characteristics of Self-Assembled InAs/GaAs Quantum Dots Investigated by Transmission Electron Microscopy

2007 ◽  
Vol 26-28 ◽  
pp. 1207-1210
Author(s):  
Hyung Seok Kim ◽  
Ju Hyung Suh ◽  
Chan Gyung Park ◽  
Sang Jun Lee ◽  
Sam Kyu Noh ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Chemical Potential ◽  
Early Stage ◽  
Compressive Strain ◽  
Potential Gradient ◽  
Growth Direction ◽  
Transmission Electron ◽  
Self Assembled

The microstructure and strain characteristics of self-assembled InAs/GaAs quantum dots (QDs) were studied by using transmission electron microscopy. Compressive strain was induced to uncapped QDs from GaAs substrate and the misfit strain largely increased after the deposition of GaAs cap layer. Tensile strain outside QD was extended along the vertical growth direction; up to 15 nm above the wetting layer. Vertically nonaligned and aligned stacked QDs were grown by adjusting the thickness of GaAs spacer layers. The QDs with a lens-shaped morphology were formed in the early stage of growth, and their apex was flattened by the out-diffusion of In atoms upon GaAs capping. However, aligned QDs maintained their lens-shaped structure with round apex after capping. It is believed that their apex did not flatten because the chemical potential gradient of In was relatively low due to the adjacent InAs QD layers.

Growth of epitaxial ZnO films on Si(111)

2002 ◽  
Vol 722 ◽  
Author(s):  
Chunming Jin ◽  
Ashutosh Tiwari ◽  
A. Kvit ◽  
J. Narayan
Keyword(s):  
Electron Microscopy ◽  
Transparent Conducting Oxide ◽  
Deposition Process ◽  
Growth Direction ◽  
Zno Films ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
X Ray ◽  
Transmission Electron ◽  
Aln Buffer

AbstractEpitaxial ZnO films have been grown on Si(111) substrates by employing a AlN buffer layer during a pulsed laser-deposition process. The epitaxial structure of AlN on Si(111) substrate provides a template for ZnO growth. The resultant films are evaluated by transmission electron microscopy, x-ray diffraction, and electrical measurements. The results of x-ray diffraction and electron microscopy on these films clearly show the epitaxial growth of ZnO films with an orientational relationship of ZnO[0001]||Aln[0001]||Si[111] along the growth direction and ZnO[2 11 0]||AlN[2 11 0]||Si[0 11] along the in-plane direction. High electrical conductivity (103 S/m at 300 K) and a linear I-V characteristics make these epitaxial films ideal for microelectronic, optoelectronic, and transparent conducting oxide applications.

Plasticity and Microstructure of Irradiated Pd

1998 ◽  
Vol 540 ◽  
Author(s):  
N. Baluc ◽  
Y. Dai ◽  
M. Victoria
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Ambient Temperature ◽  
Tensile Deformation ◽  
Microscopic Level ◽  
Macroscopic Scale ◽  
Slip Bands ◽  
Transmission Electron ◽  
Mev Protons

AbstractSingle crystalline specimens of pure Pd have been irradiated at ambient temperature with 590 MeV protons to doses ranging between 10−4 and 10−1 dpa. Tensile deformation experiments revealed that irradiation induces hardening and embrittlement, while scanning (SEM) and transmission electron microscopy (TEM) observations showed that plastic deformation of specimens irradiated to a dose ≥ 10−2 dpa is strongly localized and yields the creation of slip bands at the macroscopic scale and of defect-free channels at the microscopic level.

SiC NWs Grown on Silicon Substrate Using Fe as Catalyst

2014 ◽  
Vol 806 ◽  
pp. 39-42
Author(s):  
Paola Lagonegro ◽  
Matteo Bosi ◽  
Giovanni Attolini ◽  
Marco Negri ◽  
Sathish Chander Dhanabalan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Growth Temperature ◽  
Silicon Substrate ◽  
Growth Direction ◽  
Carrier Gas ◽  
Sic Nanowires ◽  
Transmission Electron

We report on the synthesis of SiC nanowires (NWs) using iron as catalyst. The NWs were grown on silicon substrate by vapour-liquid-solid (VLS) mechanism with propane and silane as precursors, both 3% diluted in hydrogen, and hydrogen as carrier gas. The growth temperature was 1250°C, to reach the eutectic values of the Si-Fe alloy and to permit the VLS mechanism. The as-grown SiC nanowires were characterized by scanning and transmission electron microscopy. The nanowires are from 30 to 100 nm in diameter and several μm in length, with <111> growth direction.

scholarly journals Rodlike YMn2O5 Powders Derived from Hydrothermal Process Using Oxygen as Oxidant

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 805
Author(s):  
Jun Shi ◽  
Jing Wang ◽  
Huifen He ◽  
Yang Lu ◽  
Zhongxiang Shi
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Process ◽  
Growth Direction ◽  
Hydrothermal Time ◽  
Hydrothermal Temperature ◽  
Remarkable Effect ◽  
Structure And Morphology ◽  
Transmission Electron ◽  
Stirring Time ◽  
Main Factors

A facile approach is proposed herein to fabricate YMn2O5 powders with the hydrothermal method with oxygen as an oxidant. The structure and morphology of the as-synthesized YMn2O5 powders were characterized by XRD, SEM, and high-resolution transmission electron microscopy (HRTEM). The results manifested that the main factors that affected the formation of the rod-like YMn2O5 structures were the stirring time, hydrothermal temperature, and hydrothermal time. The oxidation time in the air had a remarkable effect on the final product by oxidizing Mn2+ ions to Mn3+ ions and Mn4+ ions. The obtained YMn2O5 powder was single crystalline and possessed a nanorod morphology, where the growth direction was along the c axis. The possible formation mechanism involved a dissolution–crystallization mechanism. Under the 397 nm excitation, the Mn4+ ions exhibited an intense orange emission at 596 nm. The energy bandgap of YMn2O5 powders was 1.18 eV.

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