Transmission Electron Microscopy studies of the structure of martensitic interfaces in Cu-Zn: HRTEM

1990 ◽  
Vol 48 (4) ◽  
pp. 314-315
Author(s):  
F.-R. Chen ◽  
G. B. Olson
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Habit Plane ◽  
Parent Phase ◽  
High Resolution Electron Microscopy ◽  
Interfacial Structure ◽  
Second Phase ◽  
Invariant Line ◽  
Lattice Plane ◽  
Resolution Electron

The crystallography and interfacial structure of martensite in Cu-38.6%Zn has been studied by conventional TEM and reported in these proceedings. The parent phase is bcc and the martensite phase has a 9R close-packed structure with the stacking order “ABC/BCA/CAB/A” normal to the c axis. Here, the bcc-9R interfaces are studied by using high resolution electron microscopy. The coherency dislocation/step structure of enclosed second phase particles has been treated by Olson and Cohen. The most significant coherency dislocation/step in an interface is formed by the intersection of interface and the most close-packed lattice plane which is nearly parallel to the interface. The average habit plane of martensite in Cu-38.6%Zn determined from experiment and CRAB crystallographic theory is very close to (4 21 22)b which is 7.6° away from the most close-packed lattice plane (011)b. Therefore, the best crystallographic direction for high-resolution electron microscopy studies is [01]b where the habit plane and the (011)b are all edge-on. Unfortunately, in this beam direction there is only one set of lattice fringes from both parent and martensite phases which can be resolved and they provide little information about interfacial structure. As shown in Figure 1 the high resolution images are therefore taken along the [11]b lattice invariant line (anti-coherency dislocation line) direction where the interfacial boundary and the internal stacking faults of the martensite are near edge-on. Figure 1 (a) and (b) are in the same area but taken with different defocus. These images were taken using the Berkeley ARM operated at 800 kv.

HRTEM simulation of interfacial structure in amorphous multilayers

1989 ◽  
Vol 47 ◽  
pp. 466-467
Author(s):  
Margaret L. Sattler ◽  
Michael A. O'Keefe
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Cross Section ◽  
High Resolution Electron Microscopy ◽  
Interfacial Structure ◽  
Multilayer Sample ◽  
Resolution Electron ◽  
Multilayered Materials ◽  
Simulated Images

Multilayered materials have been fabricated with such high perfection that individual layers having two atoms deep are possible. Characterization of the interfaces between these multilayers is achieved by high resolution electron microscopy and Figure 1a shows the cross-section of one type of multilayer. The production of such an image with atomically smooth interfaces depends upon certain factors which are not always reliable. For example, diffusion at the interface may produce complex interlayers which are important to the properties of the multilayers but which are difficult to observe. Similarly, anomalous conditions of imaging or of fabrication may occur which produce images having similar traits as the diffusion case above, e.g., imaging on a tilted/bent multilayer sample (Figure 1b) or deposition upon an unaligned substrate (Figure 1c). It is the purpose of this study to simulate the image of the perfect multilayer interface and to compare with simulated images having these anomalies.

Atomic Structure of Interfaces: Link of Atomistic Calculations with High Resolution Electron Microscopy

1998 ◽  
Vol 4 (S2) ◽  
pp. 762-763
Author(s):  
V. Vitek
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Computer Modeling ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Interfacial Structure ◽  
Embedded Atom ◽  
Resolution Electron ◽  
Atomic Interactions ◽  
Atomistic Calculations

Since interfaces and grain boundaries affect critically many properties of materials, their atomic structure has been investigated very extensively using computer modeling. Most of these calculations have been made using semi-empirical central-force descriptions of atomic interactions, recently primarily the embedded-atom type many-body potentials. Owing to the approximate nature of such schemes, a connection with experimental observations that can validate the calculations is essential. The high resolution electron microscopy (HREM) is such experimental technique and it has, indeed, been frequently combined with calculations of interfacial structure and chemistry. In fact such a link is not only important for verification of the results of computer modeling but also crucial for meaningful interpretation of HREM observations. Hence, coupling the atomistic modeling with HREM is a synergistic procedure. It not only leads to better understanding of interfacial structures but may contribute significantly to the validation and assessment of limits of the schemes used for the description of atomic interactions.

A Microstructural Study of Reaction-Bonded Silicon Carbide

1992 ◽  
Vol 295 ◽  
Author(s):  
K. Das Chowdhury ◽  
R. W. Carpenter ◽  
W. Braue
Keyword(s):  
Electron Microscopy ◽  
Silicon Carbide ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Second Phase ◽  
Oxygen Impurity ◽  
Microstructural Study ◽  
Impurity Segregation ◽  
Resolution Electron ◽  
Second Phase Particles

AbstractInterfaces in Reaction Bonded Silicon Carbide (RBSC) have been characterized by Analytical and High Resolution Electron Microscopy. Both Si/SiC and SiC/SiC interfaces were free of any oxygen impurity segregation, but contained metallic impurity precipitates. Oxygen was detected in the second phase particles in the SiC grains. A model is presented to explain the evolution of these second phase particles in the SiC grains.

Structural Studies of Metal-Semiconductor Interfaces with High-Resolution Electron Microscopy

1982 ◽  
Vol 14 ◽  
Author(s):  
J. M. Gibson ◽  
R. T. Tung ◽  
J. M. Poate
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Dislocation Core ◽  
High Resolution Electron Microscopy ◽  
Nucleation And Growth ◽  
Interfacial Structure ◽  
Preparation Conditions ◽  
Semiconductor Interfaces ◽  
Resolution Electron ◽  
Crystal Films

ABSTRACTWe have studied interface atomic structure in epitaxial cobalt and nickel disilicides on silicon using high-resolution transmission electron microscopy. By employing UHV techniques during deposition and reaction we have grown truly single-crystalline NiSi2 and CoSi2 films on (111) Si and in the former case on (100) Si. These films are shown to be continuous to below 10Å thickness. By close control over preparation conditions, afforded by UHV, we can greatly influence the nucleation and growth of these films to the extent, for example with NiSi2 on (111)Si, of yielding continuous single-crystal films with either of two orientations as desired. Whilst in the (111) NiSi2 on Si system the interfacial structure invariably appears to well-fit a model in which metal atoms nearest to the interface are 7-fold co-ordinated, for (111) CoSi2 on Si agreement is generally better with a model involving 5-fold co-ordination of these atoms. A misfit dislocation core is also imaged. Results are discussed in the light of silicide nucleation and growth. The structure and stability of the (100) NiSi2 on Si interface is also considered.

High-Resolution Electron Microscopy of Planar Defects in Ain.

1990 ◽  
Vol 183 ◽  
Author(s):  
Stuart Mckernan ◽  
M. Grant Norton ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Model ◽  
Antiphase Boundary ◽  
High Resolution Electron Microscopy ◽  
Second Phase ◽  
Polycrystalline Aluminum ◽  
Basal Segment ◽  
Planar Fault ◽  
Resolution Electron

AbstractThe defects which occur in polycrystalline aluminum nitride are very detrimental to the beneficial physical and electrical properties. 'Dome-like' or 'D' defects, consisting of a flat basal fault joined to a curved planar fault, are examined by high-resolution electron microscopy. The basal segments are shown to contain a thin ∼5Å layer of a second phase and are associated with a stacking-fault and an antiphase boundary. A structural model is proposed for the defect which incorporates a layer of alumina at the basal segment of the 'D' defect. The formation of thisdefect is discussed.

scholarly journals Atomic Scale Structure of Twin Boundary In Y-Ba-Cu-O Superconductors

1989 ◽  
Vol 159 ◽  
Author(s):  
Yimei Zhu ◽  
M. Suenaga ◽  
Youwen Xu ◽  
M. Kawasaki
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Twin Boundary ◽  
Boundary Layers ◽  
Boundary Energy ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Lattice Plane ◽  
Twin Density ◽  
Resolution Electron

ABSTRACTHigh resolution electron microscopy of the twin boundary layers in YBa2(Cu1-xMx)3O7–8 for x=0 and 0.02 and M=Zn, Fe and Al showed that the boundary widths are ∼1 nm for the pure and the Zn substituted YBa2Cu3O7, 2.5∼3 nm for the Fe and Al substituted oxide. It was found that the lattice plane is shifted across the twin boundary by (1/3 ∼ 1/2)·2d(110) along the boundary. The broadening of the layer for the cases of Fe and Al is also thought to be associated with a reduction of the twin boundary energy, which also leads to an increased twin density.

TEM studies on twin boundary in YBa2Cu3O7 and YBa2(Cu0.98M0.02)3O7 (M = Zn, Al)

1990 ◽  
Vol 5 (7) ◽  
pp. 1380-1387 ◽  
Author(s):  
Yimei Zhu ◽  
Masaki Suenaga ◽  
Youwen Xu
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Twin Boundary ◽  
Boundary Layers ◽  
Boundary Energy ◽  
High Resolution Electron Microscopy ◽  
Lattice Plane ◽  
Al Substitution ◽  
Resolution Electron ◽  
High Resolution Images

High resolution electron microscopy of the twin boundary layers in YBa2(Cu1−xMx)3O7+δ for x = 0 and 0.02 and M = Zn and Al showed that the boundary widths are ∼1 nm for the pure and the Zn substituted YBa2Cu3O7 and ∼3 nm for the Al substituted oxide. From two beam contract studies and the high resolution images, it was concluded that the respective lattice plane across the boundary is shifted by (⅓–½)·2d(110) along the boundary. The broadening of the layer by the Al substitution is also thought to be a cause for the reduction of the twin boundary energy, leading to an increased twin density.

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