Microstructure and interfaces in TiB2/Ti-46Al-3Cr Alloy Composites

1995 ◽  
Vol 410 ◽  
Author(s):  
Weimin Si ◽  
Michael Dudley ◽  
Pengxing Li ◽  
Renjie Wu
Keyword(s):  
Electron Microscopy ◽  
Titanium Aluminide ◽  
Analytical Electron Microscopy ◽  
Lattice Misfit ◽  
High Resolution Electron Microscopy ◽  
Amorphous Layer ◽  
Two Phase ◽  
Titanium Aluminide Alloy ◽  
Resolution Electron ◽  
Crystallographic Orientation Relationship

ABSTRACTA ternary titanium aluminide alloy, Ti-46Al-3Cr (at%), was discontinuously reinforced with 5 vol% titanium diboride (TiB2), by an in-situ synthesis technique, resulting in a two phase γ(TiAl) (mainly) and α2(Ti3Al) matrix with randomly dispersed TiB2 particle. Interfaces of TiB2-TiAl were investigated by Analytical Electron Microscopy (AEM) and High Resolution Electron Microscopy (HREM). No consistent crystallographic orientation relationship was observed between TiB2 particle and TiAl matrix, and there was no evidence of alloying elements (such as Cr) segregation or interphase formation at the TiB2-TiAl interface. HREM results indicated that no semi-coherent interface between TiB2 and TiAl has been observed. There existed a thin amorphous layer (0.5 to 1.3 nm) at the TiB2-TiAl interface, which may accommodate the large lattice misfit across the interface and enhance the interfacial bonding.

Interface structures in polycrystalline ceramic materials

1986 ◽  
Vol 44 ◽  
pp. 468-471
Author(s):  
K. J. Morrissey
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Physical And Mechanical Properties ◽  
High Resolution Electron Microscopy ◽  
Ceramic Materials ◽  
Polycrystalline Materials ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Interface Structures

Grain boundaries and interfaces play an important role in determining both physical and mechanical properties of polycrystalline materials. To understand how the structure of interfaces can be controlled to optimize properties, it is necessary to understand and be able to predict their crystal chemistry. Transmission electron microscopy (TEM), analytical electron microscopy (AEM,), and high resolution electron microscopy (HREM) are essential tools for the characterization of the different types of interfaces which exist in ceramic systems. The purpose of this paper is to illustrate some specific areas in which understanding interface structure is important. Interfaces in sintered bodies, materials produced through phase transformation and electronic packaging are discussed.

Structure, Composition and Stability of Heterophase Boundaries

1997 ◽  
Vol 3 (S2) ◽  
pp. 673-674
Author(s):  
M. Rühle ◽  
T. Wagner ◽  
S. Bernath ◽  
J. Plitzko ◽  
C. Scheu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Elevated Temperatures ◽  
Analytical Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Advanced Materials ◽  
Bulk Crystals ◽  
Transmission Electron ◽  
Resolution Electron ◽  
The Stability

Heterophase boundaries play an important role in advanced materials since those materials often comprise different components. The properties of the materials depend strongly on the properties of the interface between the components. Thus, it is important to investigate the stability of the microstructure with respect to annealing at elevated temperatures. In this paper results will be presented on the structure and composition of the interfaces between Cu and (α -Al2O3. The interfaces were processed either by growing a thin Cu overlayer on α- Al2O3 in a molecular beam epitaxy (MBE) system or by diffusion bonding bulk crystals of the two constituents in an UHV chamber. To improve the adhesion of Cu to α -Al2O3 ultrathin Ti interlayers were deposited between Cu and α - Al2O3.Interfaces were characterized by different transmission electron microscopy (TEM) techniques. Quantitative high-resolution electron microscopy (QHRTEM) allows the determination of the structure (coordinates of atoms) while analytical electron microscopy (AEM) allows the determination of the composition with high spatial resolution.

The effect of doping Ag on the microstructure of La2/3Sr1/3MnO3 films

2002 ◽  
Vol 17 (10) ◽  
pp. 2712-2719 ◽  
Author(s):  
Q. Zhan ◽  
R. Yu ◽  
L. L. He ◽  
D. X. Li ◽  
J. Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Grain Boundaries ◽  
Doping Level ◽  
Analytical Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Plan View ◽  
Ag Doping ◽  
Low Field ◽  
Resolution Electron ◽  
Magnetic Spin

The microstructure of Ag-doped La2/3Sr1/3MnO3 (LSMO) thin films deposited on (001) LaAlO3 single-crystal substrates was systematically investigated in cross section and plan view by high-resolution electron microscopy and analytical electron microscopy. The results showed that the films deposited at 750 °C were perfectly epitaxial with or without Ag-doping. No Ag in the doped film was detected. On the other hand, the LSMO films deposited at 400 °C were less perfect. With increasing Ag-doping level, the shape of LSMO grains became irregular, and the grain size increased gradually. Large polycrystalline clusters consisting of LSMO, AgO, and Ag grains formed in the doped films, and the amount and size of them increased with increasing Ag-doping level. Ag existed at the LSMO grain boundaries in its elemental state. A growth process for the LSMO-Ag system is discussed based on the experimental results. The enhancement of the magnetic spin disorders at the grain boundaries and interfaces caused by doping Ag could result in an improvement of low-field magnetoresistance.

High resolution electron microscopy observation of interfacial structures in NiAl-matrix in situ composites reinforced by TiC particulates

1997 ◽  
Vol 12 (7) ◽  
pp. 1790-1795 ◽  
Author(s):  
L. G. Yu ◽  
J. Y. Dai ◽  
Z. P. Xing ◽  
D. X. Li ◽  
J. T. Guo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Amorphous Layer ◽  
Interfacial Layers ◽  
Resolution Electron ◽  
Interfacial Structures ◽  
Tic Particulates ◽  
Nial Matrix

The structures of interfaces in NiAl-matrix in situ composites reinforced by TiC particulates were studied by means of high-resolution electron microscopy (HREM). No consistent orientation relationship between TiC particles and the NiAl matrix was found. In most cases, TiC particles bonded well to the NiAl matrix free from any interfacial phases. However, in some cases, an interfacial amorphous layer with a thickness of about 3 nm was found. The annealed NiAl–TiC composite showed a good chemical compatibility between the TiC particles and the NiAl matrix, though, some interfacial layers between TiC and NiAl, which were determined to be C-deficient TiC, were found. NiAl precipitates were observed in the TiC particles of the annealed specimens.

Cubic silicon nitride embedded in amorphous silicon dioxide

2001 ◽  
Vol 16 (8) ◽  
pp. 2179-2181
Author(s):  
Ming Zhang ◽  
Hongliang He ◽  
F. F. Xu ◽  
T. Sekine ◽  
T. Kobayashi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Silicon Nitride ◽  
High Resolution ◽  
Analytical Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Cubic Symmetry ◽  
Resolution Electron ◽  
Microscopy Image ◽  
Wave Compression ◽  
Small Crystallite

A cubic silicon nitride embedded in amorphous SiO2 compound has been characterized by means of high-resolution analytical electron microscopy. The specimen was prepared from β–Si3N4 powders at a high pressure and temperature by shock wave compression. The typical high-resolution electron microscopy image from one small crystallite together with its diffractodiagram pattern indicated that the Si3N4 crystallites had a cubic symmetry. The electron energy loss spectrum from the small crystallite is very different from those of outside amorphous SiO2 phase and raw β–Si3N4 particles, and there are more N elements that were detected in this small crystallite than those in standard Si3N4.

Characterization of Cross-Sections of Tibacacuo Thin Films on Ceramic Substrates by Analytical and High Resolution Electron Microscopy

1989 ◽  
Vol 169 ◽  
Author(s):  
J. Mayer ◽  
M. Lanham ◽  
T.W. James ◽  
A.G. Evans ◽  
M. RÜHle
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Cross Sections ◽  
High Resolution Electron Microscopy ◽  
Amorphous Layer ◽  
Superconducting Film ◽  
Ceramic Substrates ◽  
Resolution Electron ◽  
Lattice Images

AbstractCross-sectioned TEM specimens of thin TIBaCaCuO superconducting films on MgO and LaAlO3 substrates have been obtained using special ceramic holders. The superconductor/substrate interface as well as grain boundaries and defects in the superconductor have been characterized by means of analytical and high-resolution electron microscopy. EDX analysis and lattice images confirm that interdiffusion and the formation of an amorphous layer takes place at the interface between the LaA1O3 substrate and the superconducting film, while no indication for such reactions has been found in the case of the MgO substrates. The presence of intergrowth and defects in the superconducting film have been demonstrated by high-resolution electron microscopy. The chemical nature of such defects has been determined by a quantitative evaluation of high-resolution micrographs.

High Resolution Electron Microscopy Studies On The Microstructure Of β-Si3N4w/Al Interfaces In A β-Si3N4w/6061Al Composite

1991 ◽  
Vol 238 ◽  
Author(s):  
X. G. Ning ◽  
J. Pan ◽  
K. Y. Hu ◽  
H. Q. Ye
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Amorphous Layer ◽  
Matrix Interface ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Heating Treatment ◽  
Relationship Of ◽  
Specific Orientation

ABSTRACTThe whisker/matrix interfaces in a β-Si3N4w/60 61Al composite were structurally characterized by high resolution transmission electron microscopy (HRTEM). It was shown that there was a nearly amorphous layer (2–3 nm thickness) at a whisker/matrix interface. The magnesium segregation at the whisker/Al interface was revealed by electron dispersive analysis of x-ray (EDAX). MgO and MgAl2O4 nanocrystal particles were formed at the whisker/matrix interface due to the Mg segregation there during the manufacturing of the composite. The Mg2Si particles preferred to precipitate at the whisker/Al interface when the composite was processed with T6 heating treatment. There were specific orientation relationship of the MgAl2O4 or Mg2Si particles with the β-Si3N4 whiskers.

Structures of a Stacking Fault and a Rotational Domain Boundary in CVD α-Silicon Nitride

1995 ◽  
Vol 1 (6) ◽  
pp. 263-266
Author(s):  
D.S. Zhou ◽  
T.E. Mitchell
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Domain Boundary ◽  
Analytical Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Stacking Fault ◽  
Translational Displacement ◽  
Resolution Electron ◽  
The Difference ◽  
Simulated Images

A 1/2[0001](0001) stacking fault and a planar 60° rotational domain boundary on the (0001) plane in as-grown CVD α-Si3N4 crystals have been characterized by high-resolution electron microscopy and image simulation. As reported previously, two types of coherent boundaries have been observed in this material, namely, stacking faults and rotational domain boundaries. The former involves only a translational displacement, while the latter separates two grains by a 60° rotation in addition to a translation. Inasmuch as the difference resulting from the rotational component can hardly be detected by high-resolution electron microscopy, care must be taken to analyze them first by analytical electron microscopy. In this paper, these two types of boundaries are studied and structural models are constructed that give simulated images in satisfactory agreement with observed images.

Structural and Phase Transformations in Thin Film Ti-Aluminides and Ti/Al Multilayers

1996 ◽  
Vol 434 ◽  
Author(s):  
R. Banerjee ◽  
S. Swaminathan ◽  
R. Wheeler ◽  
H. L. Fraser
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Layer Thickness ◽  
High Resolution Electron Microscopy ◽  
Silicon Substrates ◽  
Two Phase ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Sputter Deposited

AbstractMultilayered Ti/Al thin films (with nominally equal layer thickness of Ti and Al) have been sputter deposited on oxidized silicon substrates at room temperature. Transmission electron microscopy (TEM) and high resolution electron microscopy have been used to characterize the structure of these multilayers as a function of the layer thickness. Ti changed from an hcp to an fcc and back to an hcp structure on reduction of the layer thickness. Al too changed from an fcc to an hcp structure at a layer thickness of 2.5 nm. The observed structural transitions have been explained on the basis of the Redfield-Zangwill model. Subsequently Ti-aluminide thin films were deposited using a γ-TiAl target. These films were found to be amorphous in the as-deposited condition with crystallites of α-Ti(Al) embedded in the amorphous matrix. On annealing under a protective Ar atmosphere at a temperature of 550 °C, the Ti-aluminide film crystallized into a nanocrystalline two phase microstructure consisting of γ-TiAl and α2-Ti3Al. The crystallization of the aluminide film has been investigated in detail by in-situ annealing experiments on a hot stage in the TEM. The results of this investigation have been discussed in this paper.

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