The stabilization of B.C.C. Cu in Cu/Nb nanolayered composites

1996 ◽  
Vol 54 ◽  
pp. 228-229
Author(s):  
H. Kung ◽  
A.J. Griffin ◽  
Y.C. Lu ◽  
K.E. Sickafus ◽  
T.E. Mitchell ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Layer Thickness ◽  
Volume Fraction ◽  
Ion Beam ◽  
High Strength ◽  
Cross Sectional ◽  
Metastable Structure ◽  
High Resolution Tem ◽  
Potential Improvement ◽  
Two Phases

Materials with compositionally modulated structures have gained much attention recently due to potential improvement in electrical, magnetic and mechanical properties. Specifically, Cu-Nb laminate systems have been extensively studied mainly due to the combination of high strength, and superior thermal and electrical conductivity that can be obtained and optimized for the different applications. The effect of layer thickness on the hardness, residual stress and electrical resistivity has been investigated. In general, increases in hardness and electrical resistivity have been observed with decreasing layer thickness. In addition, reduction in structural scale has caused the formation of a metastable structure which exhibits uniquely different properties. In this study, we report the formation of b.c.c. Cu in highly textured Cu/Nb nanolayers. A series of Cu/Nb nanolayered films, with alternating Cu and Nb layers, were prepared by dc magnetron sputtering onto Si {100} wafers. The nominal total thickness of each layered film was 1 μm. The layer thickness was varied between 1 nm and 500 nm with the volume fraction of the two phases kept constant at 50%. The deposition rates and film densities were determined through a combination of profilometry and ion beam analysis techniques. Cross-sectional transmission electron microscopy (XTEM) was used to examine the structure, phase and grain size distribution of the as-sputtered films. A JEOL 3000F high resolution TEM was used to characterize the microstructure.

A Method for Site Specific Characterization Using a Dedicated FIB System Combined With an Analyitical TEM

1999 ◽  
Vol 5 (S2) ◽  
pp. 914-915
Author(s):  
T. Kamino ◽  
T. Yaguchi ◽  
H. Matsumoto ◽  
H. Kobayashi ◽  
H. Koike
Keyword(s):  
Focused Ion Beam ◽  
Ion Irradiation ◽  
Ion Beam ◽  
System Stability ◽  
Specimen Preparation ◽  
Thin Specimen ◽  
Cross Sectional ◽  
Site Specific ◽  
Specimen Holder ◽  
High Resolution Tem

A method for site specific characterization of the materials using a dedicated focused ion beam(FIB) system and an analytical transmission electron microscope (TEM) was developed. Needless to say, in TEM specimen preparation using FIB system, stability of a specimen is quite important. The specimen stage employed in the developed FIB system is the one designed for high resolution TEM, and the specimen drift rate of the stage is less than lnm/min. In addition, FIB-TEM compatible specimen holder which allows milling of a specimen with the FIB system and observation of the specimen with the TEM without re-loading was developed. To obtain thin specimen from the area to be characterized correctly, confirmation of the area before final milling is needed. However, observation of cross sectional view in a FIB system is recommended because it causes damage by Ga ion irradiation. To solve this problem, we used a STEM unit as a viewer of FIB milled specimen.

Electrical Resistivity And Crystal Structure Of Nickel-Based Multilayer Thin Films

1991 ◽  
Vol 238 ◽  
Author(s):  
M. Tan ◽  
E. Haftek ◽  
A. Waknis ◽  
J. A. Barnard
Keyword(s):  
Thin Film ◽  
Crystal Structure ◽  
Electrical Resistivity ◽  
Layer Thickness ◽  
Volume Fraction ◽  
Multilayer Thin Films ◽  
Multilayer Thin Film ◽  
Spacer Layer ◽  
Interfacial Material ◽  
Very High

ABSTRACTThe electrical resistivity and crystal structure of three Ni-based periodic multilayer thin film systems (Al/Ni, Ti/Ni, and Cu/Ni) have been investigated. In each series of films the Ni layer thickness was systematically varied while the thickness of the ‘spacer’ layer (Al, Ti, or Cu) was fixed. In the Al/Ni and Ti/Ni systems films with very thin Ni layers (and consequently large volume fractions of spacer and ‘interfacial’ material) yielded very high resistivities which dropped rapidly with increasing Ni thickness. By contrast, the resistivity of Cu/Ni multilayers continuously increased with Ni layer thickness due to the decline in volume fraction of high conductivity Cu. Both the Al/Ni and Ti/Ni systems exhibit Ni(111) texture in the thicker Ni layer samples. As the Ni layer thickness decreases the Ni(111) peak loses intensity and broadens due to finer grain size and increasing disorder. Al-Ni and Ti-Ni compounds are also noted. In the Cu/Ni system, however, the sharpness of the Ni(111) peak passes through a minimum as the Ni layer thickness decreases but then increases for the thinnest Ni layer samples.

A Methodology for Synthesizing High-Performance Robots Fabricated With Optimally Tailored Composite Laminates

1987 ◽  
Vol 109 (1) ◽  
pp. 74-86 ◽  
Author(s):  
C. K. Sung ◽  
B. S. Thompson
Keyword(s):  
Composite Laminates ◽  
High Performance ◽  
Volume Fraction ◽  
Three Dimensional ◽  
High Strength ◽  
Fiber Volume ◽  
Cross Sectional ◽  
Fiber Properties ◽  
Robot Arms ◽  
The Matrix

An essential ingredient of the next generation of robotic manipulators will be high-strength lightweight arms which promise high-performance characteristics. Currently, a design methodology for optimally synthesizing these essential robotic components does not exist. Herein, an approach is developed for addressing this void in the technology-base by integrating state-of-the-art techniques in both the science of composite materials and also the science of flexible robotic systems. This approach is based on the proposition that optimal performance can be achieved by fabricating robot arms with optimal cross-sectional geometries fabricated with optimally tailored composite laminates. A methodology is developed herein which synthesizes the manufacturing specification for laminates which are specifically tailored for robotic applications in which both high-strength, high-stiffness robot arms are required which also possess high material damping. The parameters in the manufacturing specification include the fiber-volume fraction, the matrix properties, the fiber properties, the ply layups, the stacking sequence and the ply thicknesses. This capability is then integrated within a finite-element methodology for analyzing the dynamic response of flexible robots. An illustrative example demonstrates the approach by simulating the three-dimensional elastodynamic response of a robot subjected to a prescribed spatial maneuver.

The Atomic, Electronic and Defect Structure of the Dynamically Formed Cu2O/Cu Interfaces

2007 ◽  
Vol 1026 ◽  
Author(s):  
Xuetian Han ◽  
Judith C. Yang
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Island Growth ◽  
Cross Sectional ◽  
Dual Beam ◽  
Transmission Electron ◽  
Initial Stage ◽  
Cu Film ◽  
High Resolution Tem ◽  
Electron Energy Loss

AbstractTo gain fundamental insights into metal oxidation, the dynamically formed Cu/Cu2O interface was investigated by cross-sectional TEM (Transmission Electron Microscopy) methods. Copper (001) films were oxidized in oxygen within a UHV chamber to create Cu2O islands that formed epitaxially with respect to the Cu film. The cross-sectional Cu2O/Cu TEM sample was prepared by dual beam (DB) focused ion beam (FIB) instrument and the interface was probed by high-resolution TEM (HREM) and electron energy loss spectrum (EELS). It is found that Cu2O {110} layer distance significantly decreases from the interface area to the bulk Cu2O region, which is about 3∼4 unit cell thickness in Cu2O side; while the {100Cu2O layer distance increases with increasing distance from the interface region. The chemical Cu/Cu2O interface thickness has been measured with EELS analysis, which is about 2nm where the oxidation state of Cu gradually changes from Cu0 to Cu+1. This transition region indicates the area where Cu/Cu2O interface exists and suggests the existence of metastable Cu oxides. The Cu2O island growth mechanism of predominantly anion interfacial diffusion at the initial stage oxidation has been proposed.

Investigation of the Microstructure of SiC-Zn Nanocomposites by Microscopic Methods: SEM, AFM and TEM

2005 ◽  
Vol 101-102 ◽  
pp. 151-156
Author(s):  
Anna Swiderska-Sroda ◽  
J.A. Kozubowski ◽  
A. Maranda-Niedbala ◽  
Ewa Grzanka ◽  
Bogdan F. Palosz ◽  
...  
Keyword(s):  
Grain Size ◽  
Volume Fraction ◽  
Infiltration Process ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
High Resolution Tem ◽  
Surface Irregularities ◽  
Two Phases ◽  
Microscopy Techniques

SiC-Zn nanocomposites with about 20% volume fraction of metal were fabricated by infiltration process under the pressure of 2-8 GPa and at the temperature of 400_1000oC. SiC nanopowders used in the experiments formed loosely agglomerated chains of single crystal nanoparticles. The dimension of the agglomerates was in the micrometer range, the mean grain size was up to tens of nanometers. Microstructural investigations of the nanocomposites were performed at a different resolution levels using scanning, transmission electron microscopy and atomic force microscopy techniques (SEM, TEM, AFM, respectively). SEM observations indicate a presence of nano-dispersed, uniform (on the micrometer scale) mixture of two phases. TEM observations show that distribution of SiC and Zn nanocrystallites is uniform on the nanometer scale. High-resolution TEM images demonstrate an existence of thin (on the order of tens of Angstroms) Zn layers separating SiC grains. AFM images of the mechanically polished samples show a smooth surface with the roughness on the order of the SiC grain size (10-30 nm). After ion etching of some samples the AFM topographs show surface irregularities: periodically spaced hillocks 50-100 nm in height. The size of the SiC grains remains equal to that of the initial powder crystallites. The size of the Zn grains varies in the range of 20-100 nm depending on the initial SiC grain size and the composite fabrication conditions.

Morphological Stability of Ni(Al)/Ni3Al Nanolaminate Composites

1999 ◽  
Vol 581 ◽  
Author(s):  
Jason P. Fain ◽  
Rajarshi Banerjee ◽  
Daniel Josell ◽  
Peter M. Anderson ◽  
Hamish Fraser ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Layer Thickness ◽  
Crystal Orientation ◽  
Volume Fraction ◽  
Morphological Stability ◽  
Morphological Instability ◽  
Columnar Grains ◽  
Two Phases ◽  
The Stability ◽  
Coherent Interfaces

ABSTRACTThis manuscript discusses the morphological instability observed when multilayered samples with alternating layers of Γ-Ni(Al)/γ-Ni3Al are exposed to 800C for approximately 100 hours. Samples with 20nm/20nm or 120nm/120nm layer thickness and <001> or <Ill> crystal orientation to the interface normal were tested. Pinching off of layers is strongly affected by crystal orientation and layer thickness. Corresponding modeling suggests that the stability of this system is sensitive to fluctuations in the volume fraction of the two phases, the aspect ratio of columnar grains in the layers, and whether coherent or semi-coherent interfaces are present.

scholarly journals Structural Transition in Cu/Fe Multilayered Thin Films

1996 ◽  
Vol 441 ◽  
Author(s):  
Tai D. Nguyen ◽  
Alison Chaiken ◽  
Troy W. Barbee
Keyword(s):  
Layer Thickness ◽  
Ion Beam ◽  
Microstructural Development ◽  
Ion Beam Sputtering ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Beam Sputtering ◽  
Bcc Structure

AbstractMicrostructural development of Fe and Cu in Cu/Fe multilayers of layer thickness 1.5–10 nm prepared on Si, Ge, and MgO substrates by ion beam sputtering has been studied using x-ray diffraction and cross-sectional transmission electron microscopy (TEM). High-angle x-ray results show an fcc Cu structure and a distorted bcc structure in the Fe layers at 5 nm-layer-thickness and smaller, and bcc Fe (110) and fcc Cu (111) peaks in the 10 nm-layer-thickness samples. Lowangle x-ray diffraction indicates that the layers in the samples grown on MgO substrates have a more uniform and smooth layered structure than the multilayers grown on Si and Ge substrates, which results from larger grains in the MgO substrate samples for the same layer thickness. Relationships among growth, microstructure, and interfaces with layer thickness are discussed.

scholarly journals Design of Nano-Composites for Ultra-High Strengths and Radiation Damage Tolerance

2009 ◽  
Vol 1188 ◽  
Author(s):  
Amit Misra ◽  
X. Zhang ◽  
M. J. Demkowicz ◽  
R. G. Hoagland ◽  
M. Nastasi
Keyword(s):  
Radiation Damage ◽  
Layer Thickness ◽  
Volume Fraction ◽  
Damage Tolerance ◽  
Ion Irradiation ◽  
Critical Role ◽  
High Strength ◽  
Model Systems ◽  
Nano Composites ◽  
Radiation Induced

AbstractThe combination of high strength and high radiation damage tolerance in nanolaminate composites can be achieved when the individual layers in these composites are only a few nanometers thick and therefore these materials contain a large volume fraction associated with interfaces. These interfaces act both as obstacles to slip, as well as sinks for radiation-induced defects. The morphological and phase stabilities of these nano-composites under ion irradiation are explored as a function of layer thickness, temperature and interface structure. Using results on model systems such as Cu-Nb, we highlight the critical role of the atomic structure of the incoherent interfaces that exhibit multiple states with nearly degenerate energies in acting as sinks for radiation-induced point defects. Reduced radiation damage also leads to a reduction in the irradiation hardening, particularly at layer thickness of approximately 5 nm and below. The strategies for design of radiation-tolerant structural materials based on the knowledge gained from this work will be discussed.

Electrical Resistivity of Multilayers During Ion Beam Mixing

1983 ◽  
Vol 27 ◽  
Author(s):  
J. Grilhe ◽  
J.P. Riviere ◽  
J. Delafond ◽  
C. Jaouen ◽  
C. Templier
Keyword(s):  
Electrical Resistivity ◽  
Volume Fraction ◽  
Ion Beam ◽  
Conduction Model ◽  
Ion Beam Mixing ◽  
New Approach ◽  
Saturation Process ◽  
Resistivity Measurements ◽  
Metal Metal

ABSTRACTA new approach is developed, employing “in situ” electrical resistivity measurements, as a tool to study ion beam mixing of evaporated metal-metal multi or bilayers. The electrical resistivity variations measured continuously during the ion bombardment exhibit a monotonical increase and a tendency toward a saturation process allowing to detect precisely the total mixing of the film. The volume fraction of intermixed atoms can be determined within the framework of a simple conduction model. Experimental results are given in the case of Fe-Al and Al-Ag multilayers.

TEM Study of Co/Pd and Co/Au Multilayers

1993 ◽  
Vol 51 ◽  
pp. 1036-1037
Author(s):  
A.E.M. De Veirman ◽  
F.J.G. Hakkens ◽  
W.M.J. Coene ◽  
F.J.A. den Broeder
Keyword(s):  
Magnetic Anisotropy ◽  
Ion Beam ◽  
Perpendicular Magnetic Anisotropy ◽  
Optical Recording ◽  
Magnetic Multilayer ◽  
Ion Beam Sputtering ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Beam Sputtering ◽  
Substrate Temperatures

There is currently great interest in magnetic multilayer (ML) thin films (see e.g.), because they display some interesting magnetic properties. Co/Pd and Co/Au ML systems exhibit perpendicular magnetic anisotropy below certain Co layer thicknesses, which makes them candidates for applications in the field of magneto-optical recording. It has been found that the magnetic anisotropy of a particular system strongly depends on the preparation method (vapour deposition, sputtering, ion beam sputtering) as well as on the substrate, underlayer and deposition temperature. In order to get a better understanding of the correlation between microstructure and properties a thorough cross-sectional transmission electron microscopy (XTEM) study of vapour deposited Co/Pd and Co/Au (111) MLs was undertaken (for more detailed results see ref.).The Co/Pd films (with fixed Pd thickness of 2.2 nm) were deposited on mica substrates at substrate temperatures Ts of 20°C and 200°C, after prior deposition of a 100 nm Pd underlayer at 450°C.

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