Thermomechanical behavior and microstructural evolution in tantalum thin films

2004 ◽  
Vol 854 ◽  
Author(s):  
Robert Knepper ◽  
Katherine Jackson ◽  
Blake Stevens ◽  
Shefford P. Baker
Keyword(s):  
Phase Transformation ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Tensile Direction ◽  
Grain Sizes ◽  
Curvature Measurement ◽  
Backscatter Diffraction

ABSTRACTTa films were prepared in the metastable β phase using an ultra-high vacuum sputter deposition system. The stresses that arose during thermal cycles to 750°C were measured using an in situ substrate curvature measurement system, allowing oxygen content in the films to be minimized. A phase transformation from β to the stable α phase takes place in conjunction with distinct “jumps” in stress in the tensile direction during heating at approximately 400°C and 650°C. X-ray and electron backscatter diffraction (EBSD) analyses were used to determine grain sizes, along with crystal phase and orientation information. These results indicate a significant amount of grain growth accompanying the phase transformation. It is found that the measured total stress change is in reasonable agreement with that predicted by the combination of grain growth, crystal densification associated with the phase transformation, and stress relaxation.

Thermomechanical Behavior of Tantalum Thin Films: The Effects of Oxygen and the β–α Phase Transformation

2003 ◽  
Vol 795 ◽  
Author(s):  
Robert Knepper ◽  
Blake Stevens ◽  
Shefford P. Baker
Keyword(s):  
Phase Transformation ◽  
Oxygen Content ◽  
High Vacuum ◽  
Sputter Deposition ◽  
Ultra High Vacuum ◽  
Annealing Atmosphere ◽  
Α Phase ◽  
Curvature Measurement ◽  
Thermomechanical Testing

ABSTRACTβ-Ta films were prepared in an ultra-high vacuum sputter deposition system, and the stresses that arose during thermal cycles to 750° C were measured using an in situ substrate curvature measurement system. The oxygen content in the environment was controlled during both deposition and thermomechanical testing. In films with no added oxygen, phase transformation from β to α takes place in distinct “jumps.” Addition of controlled amounts of oxygen to the annealing atmosphere led to increases in compressive stress, inhibited the phase transformation, and altered the magnitudes of the “jumps” in stress. The stresses in Ta films were found to be sensitive to oxygen content as well as thermal history.

Grain Growth in Al: First Results from a Combined Study of Bulk and In-Situ Experiments Using a Columnar Structured Al Foil

2004 ◽  
Vol 467-470 ◽  
pp. 935-940 ◽  
Author(s):  
Sandra Piazolo ◽  
Vera G. Sursaeva ◽  
David J. Prior
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Boundary Energy ◽  
Complete Replacement ◽  
Von Neumann ◽  
In Situ Experiments ◽  
First Results ◽  
Backscatter Diffraction

First results from grain growth experiments in a columnar structured Al foil show several interesting features: (a) the grain size distribution remains heterogeneous even after up to 300 min. annealing and (b) the Von Neumann-Mullins relation is not always satisfied. To clarify the underlying reasons for these features, in-situ heating experiments within a Scanning Electron Microscope (SEM) were combined with detailed Electron Backscatter Diffraction (EBSD) analysis. These show that the movement of boundaries can be strongly heterogeneous. For example, the complete replacement of one grain by a neighbouring grain without significant change of the surrounding grain boundary topology is frequently seen. Experiments show that grain boundary energy and/or mobility are anisotropic both with respect to misorientation and orientation of grain boundary plane. Low energy and/or mobility boundaries are commonly low angle boundaries, twin boundaries and boundaries that form traces to a low index plane of at least one of the adjacent grains. As a consequence the Von Neumann-Mullins relation is not always satisfied.

scholarly journals Investigation of the α−γ−α Phase Transformation in Steel: High-Temperature In Situ EBSD Measurements

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
I. Lischewski ◽  
D. M. Kirch ◽  
A. Ziemons ◽  
G. Gottstein
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Electron Backscatter Diffraction ◽  
Experimental Setup ◽  
Ebsd Data ◽  
Α Phase ◽  
Electron Backscatter ◽  
First Results ◽  
Backscatter Diffraction

A newly developed laser powered heating stage for commercial SEMs in combination with automated established electron backscatter diffraction (EBSD) data acquisition is presented. This novel experimental setup can be used to achieve more information about microstructure and orientation changes during grain growth, recrystallization, recovery, and phase transformations. First results on the α−γ−α phase transformation in steel within 886∘C–900∘C are presented.

Electrodeposited Nanocrystalline Ni-Fe with Banded Structure

2012 ◽  
Vol 706-709 ◽  
pp. 1618-1623 ◽  
Author(s):  
Uta Klement ◽  
Mehrdad Shahabi-Navid ◽  
Glenn D. Hibbard
Keyword(s):  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Growth Direction ◽  
Phase Changes ◽  
Growth Behaviour ◽  
General Behaviour ◽  
Banded Structure ◽  
Ebsd Technique ◽  
Backscatter Diffraction

The microstructure of a Ni–18 wt.% Fe electrodeposits having a banded structure is described in detail. The aim is to investigate the influence of the banded structure on grain growth behaviour and texture and to elucidate if there are other mechanisms operative in the stabilization of nanocrystalline electrodeposits. Spectroscopy techniques have been used to characterize the variations in alloy/impurity concentration perpendicular to the growth direction. The influence of these chemical variations on the microstructural evolution has been monitored by in-situ annealing treatments in the TEM. Local texture of the annealed material has been determined by use of the electron backscatter diffraction (EBSD) technique. SEM and TEM investigations have shown that the banded structure is not related to phase changes and that grain growth is not affected by the banded structure, i.e. there is no preferred growth along bands. The first grown grains have <100>, <112> and <111> orientations with the growth direction and upon further grain growth a <111> fibre texture with respect to the growth direction of the electrodeposits is formed. The banded structure seems not to affect the general behaviour of nanocrystalline electrodeposits.

Effect of Annealing on Microstructural Development and Grain Orientation in Electrodeposited Ni

2010 ◽  
Vol 160 ◽  
pp. 235-240 ◽  
Author(s):  
Uta Klement ◽  
L. Hollang ◽  
S.R. Dey ◽  
M. Battabyal ◽  
O.V. Mishin ◽  
...  
Keyword(s):  
Grain Growth ◽  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Microstructural Development ◽  
Growth Behaviour ◽  
Coalescence Model ◽  
Transmission Electron ◽  
Columnar Grains ◽  
Backscatter Diffraction

Thick (up to 5 mm) Ni electrodeposits were produced by the pulsed electrodeposition (PED) technique. The PED-Ni was investigated in planar and cross-sections using high resolution scanning electron microscopy. Grain size and local texture were studied by electron backscatter diffraction. Thermal stability and grain growth behaviour were investigated using in-situ annealing in the transmission electron microscope. It is observed that columnar grains are present in the material and that the orientation of grains is not uniform. Textures and in-situ annealing behaviour are compared to previous data on nanocrystalline PED-Ni and Ni-Fe, where a subgrain coalescence model adopted from recrystallization is used to describe the occurrence of abnormal grain growth upon annealing and where twinning was found to be responsible for the texture development.

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

Hetero-Epitaxy of Group Va Metals on Sapphire

1972 ◽  
Vol 30 ◽  
pp. 492-493
Author(s):  
J. E. O'Neal ◽  
J. J. Bellina ◽  
B. B. Rath
Keyword(s):  
Thermal Contact ◽  
High Vacuum ◽  
Electron Beam Evaporation ◽  
Ultra High Vacuum ◽  
Backing Plate ◽  
Sapphire Substrates ◽  
Deposition Parameters ◽  
Polishing Damage ◽  
Reflection Electron Diffraction

Thin films of the bcc metals vanadium, niobium and tantalum were epitaxially grown on (0001) and sapphire substrates. Prior to deposition, the mechanical polishing damage on the substrates was removed by an in-situ etch. The metal films were deposited by electron-beam evaporation in ultra-high vacuum. The substrates were heated by thermal contact with an electron-bombarded backing plate. The deposition parameters are summarized in Table 1.The films were replicated and examined by electron microscopy and their crystallographic orientation and texture were determined by reflection electron diffraction. Verneuil-grown and Czochralskigrown sapphire substrates of both orientations were employed for each evaporation. The orientation of the metal deposit was not affected by either increasing the density of sub-grain boundaries by about a factor of ten or decreasing the deposition rate by a factor of two. The results on growth epitaxy are summarized in Tables 2 and 3.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

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