Tensile Tests of Low Density Multilayer Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
D. van Heerden ◽  
D. Josell ◽  
D. Shechtman
Keyword(s):  
Thin Films ◽  
Tensile Tests ◽  
Low Density ◽  
Multilayer Thin Films ◽  
Free Standing ◽  
Aerospace Applications ◽  
Transmission Electron ◽  
Film Hardness ◽  
Potential Use ◽  
Mechanical Studies

AbstractAlthough mechanical studies of multilayer thin films are increasingly more abundant, the majority of studies merely determine film hardness using micro- or nanoindentation techniques. Actual tensile tests are still quite rare. We have therefore conducted tensile tests of free standing aluminum-titanium multilayer thin films. This system was selected for its potential use as a low density (3.3 g/cm3) structural material with potential aerospace applications. The strongest multilayers produced, with bilayer thicknesses 7nm Ti/16 nm Al, fractured at tensile stresses (UTS) of 900 MPa - well beyond the UTS of either of the constituent materials. Specimen characterization by xray diffraction as well as transmission electron microscopy (TEM) revealed near perfect texturing and an intriguing hcp to fec transformation of the titanium layers during preparation of samples for TEM viewing.

Tensile testing low density multilayers: Aluminum/titanium

1998 ◽  
Vol 13 (10) ◽  
pp. 2902-2909 ◽  
Author(s):  
D. Josell ◽  
D. van Heerden ◽  
D. Read ◽  
J. Bonevich ◽  
D. Shechtman
Keyword(s):  
Thin Films ◽  
Yield Stress ◽  
Tensile Testing ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Low Density ◽  
Multilayer Thin Films ◽  
Bilayer Thickness ◽  
Relationship Of ◽  
The Relationship

Yield stresses, ultimate tensile strengths, and specific strengths of aluminum/titanium multilayer thin films are determined from the results of uniaxial tensile tests. The plasticity in the stress-strain curves, the nature of the fracture surfaces, and the relationship of the yield stress and the bilayer thickness are discussed. Properties are compared with those of other multilayer materials published in the literature.

Characterization of reactive phase formation in sputter-deposited Ni/Al multilayer thin films using TEM

1996 ◽  
Vol 54 ◽  
pp. 1000-1001
Author(s):  
G. Lucadamo ◽  
K. Barmak ◽  
C. Michaelsen
Keyword(s):  
Thin Films ◽  
Phase Formation ◽  
Dark Field ◽  
Nickel Layer ◽  
Multilayer Thin Films ◽  
Cross Sectional ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Sputter Deposited ◽  
Constant Heating

The subject of reactive phase formation in multilayer thin films of varying periodicity has stimulated much research over the past few years. Recent studies have sought to understand the reactions that occur during the annealing of Ni/Al multilayers. Dark field imaging from transmission electron microscopy (TEM) studies in conjunction with in situ x-ray diffraction measurements, and calorimetry experiments (isothermal and constant heating rate), have yielded new insights into the sequence of phases that occur during annealing and the evolution of their microstructure.In this paper we report on reactive phase formation in sputter-deposited lNi:3Al multilayer thin films with a periodicity A (the combined thickness of an aluminum and nickel layer) from 2.5 to 320 nm. A cross-sectional TEM micrograph of an as-deposited film with a periodicity of 10 nm is shown in figure 1. This image shows diffraction contrast from the Ni grains and occasionally from the Al grains in their respective layers.

TEM Characterization of As-Deposited and Annealed Ni/Al Multilayer Thin Film

2010 ◽  
Vol 16 (6) ◽  
pp. 662-669 ◽  
Author(s):  
S. Simões ◽  
F. Viana ◽  
A.S. Ramos ◽  
M.T. Vieira ◽  
M.F. Vieira
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Ion Beam ◽  
Microstructural Characterization ◽  
Multilayer Thin Films ◽  
Tem Analysis ◽  
Plan View ◽  
Transmission Electron

AbstractReactive multilayer thin films that undergo highly exothermic reactions are attractive choices for applications in ignition, propulsion, and joining systems. Ni/Al reactive multilayer thin films were deposited by dc magnetron sputtering with a period of 14 nm. The microstructure of the as-deposited and heat-treated Ni/Al multilayers was studied by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) in plan view and in cross section. The cross-section samples for TEM and STEM were prepared by focused ion beam lift-out technique. TEM analysis indicates that the as-deposited samples were composed of Ni and Al. High-resolution TEM images reveal the presence of NiAl in small localized regions. Microstructural characterization shows that heat treating at 450 and 700°C transforms the Ni/Al multilayered structure into equiaxed NiAl fine grains.

Mechanisms of Grain Growth in Free-Standing Nanograined Gold Thin Films

2005 ◽  
Vol 907 ◽  
Author(s):  
J. A. Gregg ◽  
K Hattar ◽  
C H Lei ◽  
I M Robertson
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Structural Changes ◽  
Dislocation Slip ◽  
Free Standing ◽  
Transmission Electron ◽  
Enhanced Properties ◽  
Gold Thin Films ◽  
Annealing Experiments

AbstractRetention of the enhanced properties reported for nanograined metallic systems requires that the nanostructure be insensitive to temperature and deformation. In situ transmission electron microscopy annealing experiments were employed to investigate the structural changes associated with the formation of micron-sized grains in nanograined evaporated gold thin films. This abnormal grain growth occurs randomly throughout the film. Twinning but not dislocation slip occurs in the growing grains until the grain size is in the hundreds of nanometer range. The twins appear to hinder growth and for grain growth to continue the twins must either be annihilated or be able to grow with the grain concurrently.

Microstructure Characterization of Si/C Multilayer Thin Films

2013 ◽  
Vol 743-744 ◽  
pp. 910-914
Author(s):  
Ting Han ◽  
Geng Rong Chang ◽  
Yun Jin Sun ◽  
Fei Ma ◽  
Ke Wei Xu
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Post Annealing ◽  
Transmission Electron ◽  
Twin Defects ◽  
Modulation Ratio

Si/C multilayer thin films were prepared by magnetron sputtering and post-annealing in N2 atmosphere at 1100 for 1h. X-ray diffraction (XRD), Raman scattering and high-resolution transmission electron microscopy (HRTEM) were applied to study the microstructures of the thin films. For the case of Si/C modulation ratio smaller than 1,interlayer diffusion is evident, which promotes the formation of α-SiC during thermal annealing. If the modulation ratio is larger than 1, the Si sublayers are partially crystallized, and the thicker the Si sublayers are, the crystallinity increases. To be excited, brick-shaped nc-Si is directly observed by HRTEM. The brick-shaped nc-Si appears to be more regular near the Si (100) substrate but with twin defects. The results are instructive in the application of solar cells.

Characterization of pulsed laser deposited MoS2 by transmission electron microscopy

1993 ◽  
Vol 8 (11) ◽  
pp. 2933-2941 ◽  
Author(s):  
S.D. Walek ◽  
M.S. Donley ◽  
J.S. Zabinski ◽  
V.J. Dyhouse
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Solid Phase ◽  
Analytical Electron Microscopy ◽  
Pulsed Laser ◽  
Cross Sectional ◽  
Aerospace Applications ◽  
Transmission Electron ◽  
Novel Method

Molybdenum disulfide is a technologically important solid phase lubricant for vacuum and aerospace applications. Pulsed laser deposition of MoS2 is a novel method for producing fully dense, stoichiometric thin films and is a promising technique for controlling the crystallographic orientation of the films. Transmission electron microscopy (TEM) of self-supporting thin films and cross-sectional TEM samples was used to study the crystallography and microstructure of pulsed laser deposited films of MoS2. Films deposited at room temperature were found to be amorphous. Films deposited at 300 °C were nanocrystalline and had the basal planes oriented predominately parallel to the substrate within the first 12–15 nm of the substrate with an abrupt upturn into a perpendicular (edge) orientation farther from the substrate. Spherically shaped particles incorporated in the films from the PLD process were found to be single crystalline, randomly oriented, and less than about 0.1 μm in diameter. A few of these particles, observed in cross section, had flattened bottoms, indicating that they were molten when they arrived at the surface of the growing film. Analytical electron microscopy (AEM) was used to study the chemistry of the films. The x-ray microanalysis results showed that the films have the stoichiometry of cleaved single crystal MoS2 standards.

Nucleation and Growth of the First Phase in Sputter-Deposited Nb/Al Multilayer Thin Films

1995 ◽  
Vol 398 ◽  
Author(s):  
K. Barmak ◽  
S. Vivekanand ◽  
F. Ma ◽  
C. Michaelsen
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Nucleation And Growth ◽  
Grain Structure ◽  
Multilayer Thin Films ◽  
Product Phase ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Sputter Deposited

ABSTRACTThe formation of the first phase in the reaction of sputter-deposited Nb/Al multilayer thin films has been studied by power-compensated and heat-flux differential scanning calorimetry, x-ray diffraction and transmission electron microscopy. The modulation periods of the films are in the range of 10-500 nm. Both types of calorimetrie measurements, performed at a constant heating rate, show the presence of two peaks (A and B) for the formation of the single product phase, NbAl3. Isothermal calorimetrie scans show that peak A is associated with a nucleation and growth type transformation. The formation of NbAl3 is thus interpreted as a two-stage process of nucleation and lateral growth to coalescence (peak A) followed by normal growth until the consumption of one or both reactants (peak B). Transmission electron microscopy investigations of samples annealed into the first stage of NbAl3 formation show the presence of this phase at the Nb/Al interface and its preferential growth along the grain boundaries of the Al layer. The latter highlights the role of reactant phase grain structure in product phase formation.

Thickness dependence of ferroelectric domains in thin ferroelectric crystals

1994 ◽  
Vol 52 ◽  
pp. 562-563
Author(s):  
F. Tsai ◽  
J. M. Cowley
Keyword(s):  
Thin Films ◽  
Bulk Material ◽  
Ferroelectric Properties ◽  
Bulk Materials ◽  
Free Standing ◽  
Ferroelectric Crystals ◽  
Transmission Electron ◽  
Ferroelectric Domains ◽  
Domain Boundaries ◽  
Long Time

Transmission electron microscopy (TEM) has been used to study the microstructures, especially the ferroelectric domains and boundaries, of ferroelectric crystals and free-standing thin films because they are closely related to the ferroelectric properties of thin films. But, for a long time observations have been made on the assumption that the properties of ferroelectric domains and domain boundaries are the same as those of the bulk crystal, even though sometimes some evidence may have been shown that ferroelectric domains in thin films could be different from those in the bulk material. In fact, weak ferroelectricity of thin films has been noticed. It was found that the ferroelectric characteristics of thin BaTiO3 ferroelectric films deposited on substrates are different from those of bulk materials. Although in their analysis interfaces and grain boundaries are involved, the mechanism of weak ferroelectricity of thin films and the microstructures which are related to the ferroelectricity of the film remains unclear.

Interfacial Reaction in Aluminum/Carbon Multilayer Thin Films

1997 ◽  
Vol 481 ◽  
Author(s):  
K. Landry ◽  
H. Sieber ◽  
M. Sui ◽  
J. H. Perepezko
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Second Step ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Modulation Wavelength

ABSTRACTThe reaction at the interface between Al and amorphous C in Al/C multilayer thin films with modulation wavelengths of about 25nm and 125nm has been investigated by differential scanning calorimetry, X-ray diffraction, transmission electron microscopy/selected area electron diffraction and high resolution transmission electron microscopy. The reaction was found to take place in two steps. The first step onsets at about 300°C, and was identified as the diffusion of C into Al. The second step starts above 400°C, at a temperature strongly dependent on the modulation wavelength of the film, and is the formation of A14C3. The carbide has been observed to nucleate and grow inside the Al layers. The multilayer structure is preserved in the samples up to at least 550°C, and Al grains start to grow at or below 300°C.

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