Problems of Structure Evolution in Polycrystalline Films. Correlation between Grain Morphology and Texture Formation Mechanisms

1994 ◽  
Vol 145 (2) ◽  
pp. 275-281 ◽  
Author(s):  
M. Adamik ◽  
P. B. Barna ◽  
I. Tomov ◽  
D. Biro
Keyword(s):  
Grain Morphology ◽  
Structure Evolution ◽  
Formation Mechanisms ◽  
Texture Formation ◽  
Polycrystalline Films

Microstructural Characterization of Ti-6Al-4V Subjected to Fretting

2004 ◽  
Author(s):  
Dana R. Swalla ◽  
Richard W. Neu ◽  
David L. McDowell
Keyword(s):  
Oxygen Diffusion ◽  
Crack Formation ◽  
Electron Backscatter Diffraction ◽  
Grain Morphology ◽  
Microstructural Characterization ◽  
Contact Problems ◽  
Fretting Wear ◽  
Formation Mechanisms ◽  
Distribution Composition

This study is focused on characterization of microstructural changes linked to deformation and crack formation mechanisms in duplex Ti-6Al-4V specimens used in displacement controlled fretting only experiments. In particular, the effect of slip displacement amplitude and number of fretting cycles on the evolution of grain morphology, grain orientation, misorientation distribution, composition, and microhardness is investigated using electron backscatter diffraction (EBSD), energy dispersive X-ray analysis (EDX) and nanoindentation. A strong basal microtexture and significant oxygen diffusion were observed in the Ti-6Al-4V specimen that exhibited the most significant cracking. A critical slip amplitude threshold may exist for which a combination of mechanisms such as plastic deformation, grain reorientation, and oxygen diffusion occur during fretting that make conditions ideal for crack formation. The results provide insights for development and validation of computational crystal plasticity models with application to fretting and sliding contact problems. New fretting damage assessment measures have also been identified and have application for components that suffer from fretting wear and/or fatigue related failures.

Microstructural Characterization of Ti-6Al-4V Subjected to Fretting

2004 ◽  
Vol 126 (4) ◽  
pp. 809-816 ◽  
Author(s):  
Dana R. Swalla ◽  
Richard W. Neu ◽  
David L. McDowell
Keyword(s):  
Oxygen Diffusion ◽  
Crack Formation ◽  
Electron Backscatter Diffraction ◽  
Grain Morphology ◽  
Microstructural Characterization ◽  
Contact Problems ◽  
Fretting Wear ◽  
Formation Mechanisms ◽  
Distribution Composition

This study is focused on characterization of microstructural changes linked to deformation and crack formation mechanisms in duplex Ti-6Al-4V specimens used in displacement controlled fretting-only experiments. In particular, the effect of slip displacement amplitude and number of fretting cycles on the evolution of grain morphology, grain orientation, misorientation distribution, composition, and microhardness is investigated using electron backscatter diffraction (EBSD), energy dispersive X-ray analysis (EDX), and nanoindentation. A strong basal microtexture and significant oxygen diffusion were observed in the Ti-6Al-4V specimen that exhibited the most significant cracking. A critical slip amplitude threshold may exist for which a combination of mechanisms, such as plastic deformation, grain reorientation, and oxygen diffusion, occur during fretting that make conditions ideal for crack formation. The results provide insights for development and validation of computational crystal plasticity models with application to fretting and sliding contact problems. New fretting damage-assessment measures have also been identified and have application for components that suffer from fretting wear and/or fatigue related failures.

Microstructural Observations of LPCVD Double Layer Polysilicon Thin Film Tensile Specimens

1997 ◽  
Vol 472 ◽  
Author(s):  
M. Legros ◽  
M. Kumar ◽  
S. Jayaraman ◽  
K. J. Hemker ◽  
W. N. Sharpe
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Double Layer ◽  
Polycrystalline Silicon ◽  
Mechanical Performance ◽  
Testing Machine ◽  
Grain Morphology ◽  
Polycrystalline Films ◽  
Tensile Testing Machine ◽  
Plan View

ABSTRACTThe vast majority of micro electro-mechanical systems fabricated today depend on polycrystalline silicon thin films for structural support. Studies involving the mechanical performance of these thin films have progressed to the point where the elastic properties and tensile strength of the films can routinely be measured using a specially designed microsample tensile testing machine. However, a fundamental understanding to predict the mechanical behavior of the polycrystalline silicon films requires that these experimental measurements be complemented with detailed observations of the underlying thin film microstructure. This paper describes some of the plan view and cross-section transmission electron microscope observations that have been performed on different deposition runs of double layer polycrystalline films obtained from the Microelectronics Center of North Carolina. The emphasis has been placed on determining the flatness and dimensions of the polycrystalline films, grain morphology and distribution, texture, and dislocation substructure and microtwinning in the undeformed films.

The dislocation structure of a 10° [110] tilt boundary in silicon

1983 ◽  
Vol 41 ◽  
pp. 114-115
Author(s):  
B. Cunningham ◽  
D.G. Ast
Keyword(s):  
Dislocation Structure ◽  
Tilt Angle ◽  
Imaging Technique ◽  
Diamond Lattice ◽  
Tilt Boundary ◽  
Formation Mechanisms ◽  
Diffraction Contrast ◽  
Lattice Fringe ◽  
Tilt Boundaries ◽  
Chemically Vapor Deposited

There have Been a number of studies of low-angle, θ < 4°, [10] tilt boundaries in the diamond lattice. Dislocations with Burgers vectors a/2<110>, a/2<112>, a<111> and a<001> have been reported in melt-grown bicrystals of germanium, and dislocations with Burgers vectors a<001> and a/2<112> have been reported in hot-pressed bicrystals of silicon. Most of the dislocations were found to be dissociated, the dissociation widths being dependent on the tilt angle. Possible dissociation schemes and formation mechanisms for the a<001> and a<111> dislocations from the interaction of lattice dislocations have recently been given.The present study reports on the dislocation structure of a 10° [10] tilt boundary in chemically vapor deposited silicon. The dislocations in the boundary were spaced about 1-3nm apart, making them difficult to resolve by conventional diffraction contrast techniques. The dislocation structure was therefore studied by the lattice-fringe imaging technique.

Formation Mechanisms for Multiply Twinned Particles During Nucleation in the Au/MICA System

1975 ◽  
Vol 33 ◽  
pp. 84-85
Author(s):  
Eal H. Lee ◽  
Helmut Poppa
Keyword(s):  
Deposition Time ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Formation Mechanisms ◽  
Heat Treated ◽  
Cluster Density ◽  
Diffraction Patterns ◽  
Crystal Particle ◽  
Multiply Twinned Particles

The formation of thin films of gold on mica has been studied in ultra-high vacuum (5xl0-10 torr) . The mica substrates were heat-treated for 24 hours at 375°C, cleaved, and annealed for 15 minutes at the deposition temperature of 300°C prior to deposition. An impingement flux of 3x1013 atoms cm-2 sec-1 was used. These conditions were found to give high number densities of multiple twin particles and are based on a systematic series of nucleation experiments described elsewhere. Individual deposits of varying deposition time were made and examined by bright and dark field TEM after "cleavage preparation" of highly transparent specimens. In the early stages of growth, the films generally consist of small particles which are either single crystals or multiply twinned; a strong preference for multiply twinned particles was found whenever the particle number densities were high. Fig. 1 shows the stable cluster density ns and the variation with deposition time of multiple twin particle and single crystal particle densities, respectively. Corresponding micrographs and diffraction patterns are shown in Fig. 2.

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