Al-Cu-Fe quasicrystalline coatings and composites studied by mechanical spectroscopy

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Raman microscopy is applied to a gel-spun UHMWPE-fibre (Dyneema SK60) to determine the distribution of axial molecular stresses and their change with time (in creep and during stress relaxation). A more detailed method is proposed to quantify the observed characteristic changes in local stress distribution. The increase in highly overstressed bonds (5 8 GPa) is ascribed to the straining of tie-molecules during creep. Their pull-out, crystal plasticity and grain-boundary slip determine stress relaxation. A r

We present the design, fabrication and test of high-Q factor radiofrequency planar microcoils for nuclear magnetic resonance (NMR) spectroscopy in small volume samples. The coils are fabricated on glass wafers using high-aspect ratio SU-8 photoepoxy and copper electroplating. On-wafer electrical characterization shows quality factors up to 40 at 800 MHz. A 500 μm diameter microcoil with a measured quality factor of 24 at 300 MHz is mounted on a printed circuit board and electrically contacted using aluminum

The 10CrMoNbV Manet II cast has been selected as the reference ferritic-martensitic steel in the framework of the European Fusion Technology Programme. Charpy impact tests have been carried out in the ductile to brittle transition temperature range of this steel, such that a dynamic quasi-equilibrium has been achieved in the process zones of investigated specimens before brittle failure. This type of testing enables the evaluation of dynamic Weibull moduli and, consequently, dynamic Weibull master curves. T

The differences and similarities of behaviour between fee and bcc metals after irradiation have been investigated. For this purpose, fee Cu, Pd and 304 stainless steel and bcc Fe, Mo and Mo-5% Re were irradiated with either neutrons or 590 MeV protons at temperatures below recovery stage V. It is shown that a dense population of defect clusters (up to 10(22)-10(24) m(-3)) develops, the type of cluster formed depending apparently on the stacking fault energy. In the case of stacking fault tetrahedra formed i

Nickel-aluminium intermetallics constitute interesting systems for the study of irradiation-induced phase transformations (order → disorder, amorphization) and production of defects. Irradiation of ordered intermetallics may induce disorder or amorphization depending on the projectile characteristics, irradiation conditions and chemical and physical properties of the target. The behavior of the various intermetallic compounds of the nickel-aluminium system with respect to electron and ion irradiation has be

Electrode stability, interdiffusion, phase purity and deviation from stoichiometry at the PZT-electrode interface are key issues in PZT thin film integration. This article highlights the use of transmission electron imaging combined with energy dispersive spectroscopy (EDS) for the investigation of these phenomena. The accuracy of the EDS analysis is discussed. It will be shown that using a standard PZT sample and controlled conditions, reliable analysis can be performed. Diffusion mechanisms have been stud

The spectroscopy of Hg2 mols. in Ne matrixes was studied using absorption, excitation and emission spectroscopy. Emission spectra show fluorescence from the lowest A0g+ and the B1g states, sepd. by .apprx.1500 cm-1, to the ground state X0+g. Their excitation spectra show clearly the absorption bands of the D1u and F0u+ states. The relaxation processes leading to the B and A emission bands are discussed. At higher excitation laser power, emission from the G0u+ state to the ground state is also obsd. Also, se

Tensile properties have been investigated on the low activation F82H ferritic/martensitic steels for both unirradiated and irradiated material. The irradiations have been carried out with protons of medium energy (590 MeV) at the PIREX facility and doses from 0.2 up to 1.75 dpa have been reached for temperature ranging between 310 and 673 K. The irradiation induced hardening has been systematically measured at room temperature for the different irradiation conditions (dose and irradiation temperature). The

The compression of visual information in the framework of multimedia applications is discussed. To this end, major approaches to compress still as well as moving pictures are reviewed. The most important objective in any compression algorithm is that of compression efficiency. High-compression coding of still pictures can be split into three categories: waveform, second-generation, and fractal coding techniques. Each coding approach introduces a different artifact at the target bit rates. The primary object

We have evaluated the structure of high-reflectivity InP/InGaAsP distributed Bragg reflectors grown by chemical-beam epitaxy at a growth rate of 3 mu m/h. Transmission electron microscopy combined with electron energy loss spectroscopy indicate lateral fluctuations in the GaInAsP alloy composition, clearly visible in the 490-510 degrees C growth temperature range, but less perceptible between 460 and 480 degrees C. In the higher temperature range, the modulation in composition shows a higher frequency along

We report a first-principle study of the E(1) defect in alpha-quartz and of the analogous E'(gamma) defect in amorphous SiO2. Our calculation supports the attribution of both these defects to a positively charged oxygen vacancy. The ground-state configuration of these defects is characterized by a large local relaxation of the atomic network, which leads to a localization of the unpaired electron on a Si dangling bond. Using the calculated electronic spin densities, we fully characterize the hyperfine inter

Two tensile-strained GaxIn1-xP / InP (001) heterostructures (with x = 6.5% and x = 11.2%) have been studied by TEM and cathodoluminescence. In both structures stacking faults and twins, located in the epilayer, have been found preferably along the [(1) over bar 10] direction whereas perfect misfit dislocations have been observed at the interface in the [110] and [(1) over bar 10] directions. The two types of structures differ about the nature of the misfit dislocations and about the thickness of the twins a

Al-Cu-Fe quasicrystalline coatings and composites studied by mechanical spectroscopy

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Structure and deformation mechanisms in UHMWPE-fibres

High-Q factor RF planar microcoils for micro-scale NMR spectroscopy

Geometry dependent ductile to brittle transition of 10CrMoNbV ferritic-martensitic steel Manet II in terms of critical crack sizes

The microstructure and associated tensile properties of irradiated fcc and bcc metals

The order-disorder transformation and microstructure evolution in nickel-aluminium intermetallics after heavy-ion irradiation

Stoichiometry and interdiffusion in PZT thin films studied by transmission electron microscopy

Spectroscopy and energy relaxation processes of Hg2 and Hg in solid Ne

Evolution of the mechanical properties of the F82H ferritic/martensitic steel after 590 MeV proton irradiation

Visual Data Compression for Multimedia Applications

Evaluation of InP/InGaAsP distributed Bragg reflectors grown by chemical-beam epitaxy

Structure and hyperfine parameters of E'(1) centers in a-quartz and in vitreous SiO2

Cathodoluminescence and TEM investigations of stress relaxation mechanisms in GaxIn1-xP/InP heterostructures