TEM Characterization of Planar Defects in A Massively Transformed TiAl Alloy

1996 ◽  
Vol 460 ◽  
Author(s):  
X. D. Zhang ◽  
J. M. K. Wiezorek ◽  
M. J. Kaufman ◽  
M. H. Loretto ◽  
H. L. Fraser
Keyword(s):  
Tial Alloy ◽  
Al Alloy ◽  
Planar Defects ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Different Types ◽  
High Resolution Tem ◽  
Diffraction Patterns ◽  
Matrix Domains

ABSTRACTThe microstructure of a massively transformed Ti-49at.%Al alloy has been studied by conventional transmission electron microscopy (CTEM) and high resolution TEM (HREM). A high density of planar defects, namely complex anti-phase domain boundaries (CAPDB) and thermal micro-twins (TMT) have been observed. CTEM images and diffraction patterns showed that two anti-phase related γ-matrix domains were generally separated by a thin layer of a 90°-domain, for which the c-axis is rotated 90° over a common cube axis with respect to those of the γ-matrix domains. HREM confirmed the presence of two crystallographically different types of 90°-do-mains being associated with the CAPDB. Furthermore, interactions between the CAPDB and TMT have been observed. Local faceting of the generally wavy, non-crystallographic CAPDB parallel to the {111}-twinning planes occurred due to interaction with the TMT. The relaxation of the CAPDB onto {111} required diffusion which is proposed to be enhanced locally in the presence of the dislocations associated with the formation of TMT during the massive transformation.

Processing of Copper by Equal Channel Angular Pressing (ECAP) – Microstructure Investigations

2015 ◽  
Vol 641 ◽  
pp. 286-293
Author(s):  
Beata Leszczyńska-Madej ◽  
Maria W. Richert ◽  
Agnieszka Hotloś ◽  
Jacek Skiba
Keyword(s):  
Equal Channel Angular Pressing ◽  
Room Temperature ◽  
Subgrain Size ◽  
Pure Copper ◽  
Shear Bands ◽  
Angular Pressing ◽  
Ecap Process ◽  
Transmission Electron ◽  
Different Types ◽  
Diffraction Patterns

The present study attempts to apply Equal-Channel Angular Pressing (ECAP) to 99.99% pure copper. ECAP process was realized at room temperature for 4, 8 and 16 passes through route BC using a die having angle of 90°. The microstructure of the samples was investigated by means both light and transmission electron microscopy. Additionally the microhardness was measured and statistical analysis of the grains and subgrains was performed. Based on Kikuchi diffraction patterns misorientation was determined. There were some different types of bands in the microstructure after deformation. The shear bands, bands and in the submicron range the microshear bands and microbands are a characteristic feature of the microstructure of copper. Also characteristic was increasing of the number of bands with increasing of deformation and mutually crossing of the bands. The intersection of a bands and microbands leads to the formation of new grains with the large misorientation angle. The measured grain/subgrain size show, that the grain size is maintained at a similar level after each stage of deformation and is equal to d = 0.25 – 0.32 μm.

Microstructral Investigations on GaN Films Grown by Laser Induced Molecular Beam Epitaxy

1999 ◽  
Vol 595 ◽  
Author(s):  
H. Zhou ◽  
F. Phillipp ◽  
M. Gross ◽  
H. Schröder
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Threading Dislocations ◽  
Planar Defects ◽  
Sapphire Substrates ◽  
Inversion Domain ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Line Defects ◽  
Inversion Domain Boundaries

AbstractMicrostructural investigations on GaN films grown on SiC and sapphire substrates by laser induced molecular beam epitaxy have been performed. Threading dislocations with Burgers vectors of 1/3<1120>, 1/3<1123> and [0001] are typical line defects, predominantly the first type of dislocations. Their densities are typically 1.5×1010 cm−2 and 4×109 cm−2 on SiC and sapphire, respectively. Additionally, planar defects characterized as inversion domain boundaries lying on {1100} planes have been observed in GaN/sapphire samples with an inversion domain density of 4×109 cm−2. The inversion domains are of Ga-polarity with respect to the N-polarity of the adjacent matrix. However, GaN layers grown on SiC show Ga-polarity. Possible reasons for the different morphologies and structures of the films grown on different substrates are discussed. Based on an analysis of displacement fringes of inversion domains, an atomic model of the IDB-II with Ga-N bonds across the boundary was deduced. High resolution transmission electron microscopy (HRTEM) observations and the corresponding simulations confirmed the IDB-II structure determined by the analysis of displacement fringes.

Growth and Characterization of Cobalt-filled Carbon Nanotubes Prepared by a Simple Catalytic Method

2003 ◽  
Vol 776 ◽  
Author(s):  
Xicheng Ma ◽  
Yuanhua Cai ◽  
Xia Li ◽  
Ning Lun ◽  
Shulin Wen
Keyword(s):  
Carbon Nanotubes ◽  
Metallic Nanoparticles ◽  
Low Cost ◽  
Catalytic Method ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
One Step

AbstractHigh-quality cobalt-filled carbon nanotubes (CNTs) were prepared in situ in the decomposition of benzene over Co/silica-gel nano-scale catalysts. Unlike the previous reports, the catalysts needn't be pre-reduced prior to the forming of Co-filled CNTs, thus the advantage of this method is that Co-filled CNTs can be produced in one step, at a relatively low cost. Transmission electron microscopy (TEM) investigation showed that the products contained abundance of CNTs and most of them were filled with metallic nanoparticles or nanorods. High-resolution TEM (HRTEM), selected area electron diffraction (SAED) patterns and energy dispersive X-ray spectroscopy (EDS) confirmed the presence of Co inside the nanotubes. The encapsulated Co was further identified always as high temperature alpha-Co phase with fcc structure, which frequently consists of twinned boundaries and stacking faults. Based on the experimental results, a possible growth mechanism of the Co-filled CNTs was proposed.

Characterization of Intermetallic Phases and Planar Defects in Mg-Y-Zn Alloys

2007 ◽  
Vol 561-565 ◽  
pp. 151-154 ◽  
Author(s):  
Yu Man Zhu ◽  
A.J. Morton ◽  
Jian Feng Nie
Keyword(s):  
Intermetallic Phases ◽  
Appreciable Amount ◽  
Planar Defects ◽  
Solution Treated ◽  
Intermetallic Particles ◽  
Transmission Electron ◽  
Characteristic Features ◽  
Mould Casting ◽  
Zn Alloys

The structure of intermetallic phases and planar defects in the as-cast and the solutiontreated microstructures of a Mg-8Y-2Zn-0.6Zr (wt%) alloy are characterized using transmission electron microscopy. The alloy was produced by permanent mould casting and solution treated at 500 °C. It is found that the intermetallic particles in the as-cast microstructure have a monoclinic structure. An appreciable amount of intermetallic particles is still retained along grain boundaries after solution treatments for up to 60 hrs. However, the structure of the retained intermetallic particles changes gradually from monoclinic to hexagonal during the solution treatments. Some planar defects are also detected in the as-cast and the solution-treated (1 hr) microstructures. These defects have characteristic features of stacking faults.

Characterization of the Ni/NiO, Interface Region in Oxidized High Purity Nickel by Transmission Electron Microscopy

1985 ◽  
Vol 48 ◽  
Author(s):  
Howard T. Sawhill ◽  
Linn W. Hobbs
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Purity ◽  
Structure Factor ◽  
Dihedral Angles ◽  
Interfacial Energies ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Interface Structures

ABSTRACTNi/NiO interface structures were investigated using TEM, and the observed structures were compared with current heterophase interface models. Relative magnitudes of Ni/NiO interfacial energies were obtained from measurements of dihedral angles at triple grain junctions between Ni and NiO grains. Extra reflections in diffraction patterns from oxide grains adjacent to the Ni/NiO interface were compared with kinematical structure factor calculations for several proposed structures.

Crystalline to Amorphous Transformation of Fe3B By 1 MeV Electron Irradiation

1981 ◽  
Vol 7 ◽  
Author(s):  
A. Mogro-Campero ◽  
E.L. Hall ◽  
J.L. Walter ◽  
A.J. Ratkowski
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Electron Irradiation ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Rapid Quenching ◽  
Al Alloy ◽  
Bright Field ◽  
Transmission Electron ◽  
Diffraction Patterns

ABSTRACTSpecimens of amorphous Fe75B25 produced by rapid quenching from the melt were annealed to complete crystallization and subjected to 1 MeV electron irradiation in a transmission electron microscope at room temperature and at 130 K. The irradiation was interrupted at various intervals in order to obtain bright field images and diffraction patterns. The Fe3B crystals did not become amorphous at room temperature, even after damage levels of several dpa, whereas at 130 K the crystalline to amorphous transformation was observed to be complete at damage levels below 1 dpa. The results are combined with those of ion irradiation work on Fe3B; qualitative agreement is found between Fe3B and previous work on the Zr3Al alloy concerning their response to displacement damage by electron and ion irradiation.

High-resolution TEM and XRD simulation of stacking disorder in 2:1 phyllosilicates

2008 ◽  
Vol 223 (01-02) ◽  
Author(s):  
Toshihiro Kogure ◽  
Jun Kameda
Keyword(s):  
High Resolution ◽  
Lateral Displacement ◽  
X Ray ◽  
Transmission Electron ◽  
Significant Difference ◽  
High Resolution Tem ◽  
Interlayer Region ◽  
Diffraction Patterns ◽  
Two Alternatives ◽  
Stacking Disorder

Stacking disorder is a common phenomenon in phyllosilicates but its nature is difficult to be deduced using conventional diffraction techniques. In contrast, recent investigations using high-resolution transmission electron microscopy (HRTEM) have elucidated the structure of stacking disorder in various phyllosilicates, by directly observing individual layers and stacking sequences. Furthermore, simulations of X-ray or electron diffraction patterns using the information from the HRTEM results can complement the limited analysis area in TEM and quantify the density of the stacking disorder.Although the bonding between adjacent layers is similar, there is a significant difference in the stacking disorder between two counterparts of dioctahedral and trioctahedral 2 : 1 phyllosilicates: pyrophyllite vs. talc and sudoite vs. trioctahedral chlorite. In pyrophyllite and sudoite, stacking disorder is caused mainly by two alternatives of the lateral displacement directions between the two tetrahedral sheets across the interlayer region. On the other hand, rotation of 2 : 1 layer is also an origin of the stacking disorder in talc and trioctahedral chlorite. This difference is explained by the corrugation of basal oxygen planes on the dioctahedral 2 : 1 layer formed by the tetrahedral tilting to enlarge

Ionic Liquid – Assisted Synthesis and Characterization of Cerium Oxide Nanocubes for Degradation of Methylene Blue

2014 ◽  
Vol 625 ◽  
pp. 164-167
Author(s):  
Mohd Aliff Irham Md. Azhar ◽  
Sujan Chowdhury ◽  
Pradip Chandra Mandal ◽  
Muhd Fahmi Daman ◽  
Sekhar Bhattacharjee ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Ionic Liquid ◽  
Cerium Oxide ◽  
Treatment Method ◽  
Acetate Anion ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Different Types ◽  
Average Size

Cerium Oxide (CeO2) nanocubes are synthesized by using hydrothermal treatment method in the presence of four different types of ionic liquid such as acetate anion, phosphate anion, and dicyanamide anion. Ceria nanocubes has been consisted with average size of 16 to 31 nm in diameter and characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), and surface analyzer and porosimetry analysis (ASAP). Ceria nanocubes have higher photocatalytical ability in the degradation of methylene blue as compared to commercial ceria nanoparticles which are confirmed through ultraviolet-visible spectroscopy (UV/Vis).

Characterization of Al2O3 in High-Strength Mo Alloy Sheets by High-Resolution Transmission Electron Microscopy

2016 ◽  
Vol 22 (1) ◽  
pp. 122-130 ◽  
Author(s):  
Yucheng Zhou ◽  
Yimin Gao ◽  
Shizhong Wei ◽  
Yajie Hu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
High Resolution ◽  
Boundary Migration ◽  
Recrystallization Temperature ◽  
Rolled Sheet ◽  
Transmission Electron ◽  
Diffraction Patterns

AbstractA novel type of alumina (Al2O3)-doped molybdenum (Mo) alloy sheet was prepared by a hydrothermal method and a subsequent powder metallurgy process. Then the characterization of α-Al2O3 was investigated using high-resolution transmission electron microscopy as the research focus. The tensile strength of the Al2O3-doped Mo sheet is 43–85% higher than that of the pure Mo sheet, a very obvious reinforcement effect. The sub-micron and nanometer-scale Al2O3 particles can increase the recrystallization temperature by hindering grain boundary migration and improve the tensile strength by effectively blocking the motion of the dislocations. The Al2O3 particles have a good bond with the Mo matrix and there exists an amorphous transition layer at the interface between Al2O3 particles and the Mo matrix in the as-rolled sheet. The sub-structure of α-Al2O3 is characterized by a number of nanograins in the $\left[ {2\bar{2}1} \right]$ direction. Lastly, a new computer-based method for indexing diffraction patterns of the hexagonal system is introduced, with 16 types of diffraction patterns of α-Al2O3 indexed.

On the Role of Characterization in the Design of Interfaces in Nanoscale Materials Technology

2004 ◽  
Vol 10 (3) ◽  
pp. 324-335 ◽  
Author(s):  
S.P. Ringer ◽  
K.R. Ratinac
Keyword(s):  
Three Dimensional ◽  
Atom Probe ◽  
Turbine Rotor ◽  
Clay Nanocomposites ◽  
Multimodal Approach ◽  
Transmission Electron ◽  
Different Types ◽  
And Control

This work reviews recent research on the design and control of interfaces in engineering nanomaterials. Four case studies are presented that demonstrate the power of a multimodal approach to the characterization of different types of interfaces. We have used a combination of conventional, high resolution, and analytical transmission electron microscopy, microbeam electron diffraction, and three-dimensional atom probe to study polymer–clay nanocomposites, turbine rotor steels used for power generation, multicomponent aluminum alloys, and nanocrystalline magnetic materials.

Sign in / Sign up

Export Citation Format

Share Document