Two-dimensional geometry information contained in SAED spot patterns augmented with EDS elemental data is employed in a computerized phase identification of microcrystalline particles. The initial chemistry screening of a laboratory managed database using the 'bitmap' concept is followed by a geometry search/match treating of the spot patterns as planar sections through the reciprocal lattice of a candidate phase. The identification is selective, fast, and yields to a complete automatization,

For many years Layered Synthetic Microstructures (LSM's) have been used successfully as dispersive devices. The commercial variety introduced in 1984 offered significantly greater stability and diffracted intensity characteristics over Thallium Acid Phthalate (TAP) crystals. These devices offer superior sensitivity for fluorine, sodium and magnesium in all but a few applications where resolution is very critical. Subsequently, a variety of these devices have been optimised for analysis of the lower atomic number elements.

Recently, several industrial applications have required the development of LSM's with 2d spacings optimised to enable quantitative analysis of oxygen, nitrogen, carbon and even boron. In these applications, the large incremental difference in characteristic wavelength per atomic number step limits the dynamic range of elements over which the LSM can be optimised. These considerations are discussed as they relate to routine analyses of very low atomic number elements by sequential Wavelength Dispersive Spectrometry (WDS).

Newly developed fabrication techniques are used to produce curved LSM's for use with the focusing optics of simultaneous WDS. Application of these curved devices for the analysis of Mg in steel, Na in slags and F in glass will be discussed.

Finally, an application which requires the analysis of thin films on semiconductor devices will be described. In this method, characteristic K-spectra and L-spectra of low and high atomic number elements, respectively, are selected for optimum sensitivity to the surface composition.

When the accuracy of a lattice parameter determination is carried beyond about 0.01 % it becomes of special importance to consider the equivalence of λ and θ in solving the Bragg equation for d. A reference angle on the observed diffractometer profile must be identified with the corresponding wavelength, of the incident X-ray spectral distribution. Exact identity is not possible because the diffractometer profiles are broadened, distorted asymmetrically, and displaced from their correct positions by amounts dependent on the shape of the incident spectral lines, the angular separation of the Kα1,2 doublet lines, and the specimen, instrumental, and geometrical aberrations innerent in the experimental method. The aberration functions vary with the experimental conditions and are Bragg-angle-dependent, thereby introducing systematic errors which are not eliminated by extrapolation procedures.

Most of the published diffractometer measurements of lattice parameters have used as the reflection angle, 28, of the diffractometer profile the peak P(2θ) or the midpoint of chords at various heights above background M1/2(2θ), M2/3(2θ), etc., of the Kα1 line. The relationship between these various angular measures of the line profile is not constant; P(2θ) may be equai to, greater than, or less than M1/2(2θ), depending on the asymmetry of the line profile. The X-ray wavelengths currently used in diffractometry refer to the peak P(λ) of the spectral distribution. The use of P(λ) with different angular measures of the diffractometer profiles results in a range of d's from which different values of the lattice parameters are calculated. The selection of arbitrary methods of defining 2θ does not take into account the significant aspects of the diffraction process, nor does it facilitate the correction of the data for systematic errors inherent in the experimental measurements.

Some of the characteristics of X-ray generation by proton bombardment are described. With work still in progress, it has been proven that this method is particularly suitable for soft X-rays >10 Å. Excitation efficiencies equal or excel electron excitation efficiencies, while the resulting spectrum consists of a single characteristic radiation line, but with complete absence of bremsstrahlung. Experimental results, the design of an instrument, and some applications are discussed.

An array of molecules that is anisotropic in the extreme has been discovered in certain thermal-energy storage materials and is reported here: neopentylglycol (NPG) and NPG-rich solid solutions with pentaglycerine (PG) have a crystal structure, stable at room temperature, that consists of bimolecular chains of molecules that are all unidirectionally aligned throughout a crystal. There are hydrogen bonds between every molecule in one chain and its neighbors in that chain, but none between molecules of one chain and any molecules of the neighboring parallel chains. Thus there are strong intermolecular bonds along each chain and only weaker bonds between the chains. The structure has been determined by using modern single crystal techniques with 529 independent reflections from a crystal of NPG (C5H12O2). The structure is monoclinic with space group P21/c - C2h5. This anisotropic structure transforms to a cubic structure at higher temperatures.

Kramers described the cross section of electron interaction with target atoms of atomic number Z by

where Eo is the kinetic energy of impinging electrons, and E o S) the energy of x-ray photons of the continuum, Smith et al modified this equation, introducing an exponent x, so that

We applied the cross-section σS, E to the evaluation of experimental results. The evaluation of the measured spectral responses of the x-ray signals nE was performed by

where f(deff) describes the absorption of x-rays of energy E in the target, RE accounts for backscattering of electrons, DE quantifies the efficiency of x-ray detection within the solid angle Ω.

Using an X-ray diffractonieter cryostat, the lattice constants of the isotopes 20Ne and 22Ne as well as the naturally occurring mixture have been measured throughout most of the temperature range in which they exist as solids (0 to approximately 24°K), The heavier isotope has the smaller lattice constant, the values obtained at 4.2°K being: 20Ne—4.4624 Å, 22Ne—4.4540 Å, and 11Ne—4.4622 Å. The absolute error in these values is believed to be no greater than 0.001 A. The volume expansion coefficient, which does not appear to differ significantly in the three cases, increases to a value of 6.3 × 10−3/°K at 24°K.

In the current work an attempt was made to apply the fundamental parameter method to the analysis of boron, oxygen, fluorine and heavier components of silica glasses. Experimental results are presented and compared with calculations based on theoretical work. The specimens consist of sets of certified standards which were obtained from Breitlahder company, Germany.

Furthermore, it is shown that the match between the certified compositions and fundamental parameter computations is affected by the quality of available fundamental parameters for the ultralight elements as well as by the underlying mathematical models. Especially in quantitative analysis of these elements, a large variety of secondary enhancement effects must be taken into account. Two major mechanisms have been considered in the presented computations: excitation by fluorescence photons emitted from aiJ available excited atoms, and excitation by photoelectrons ejected after the primary ionization event. Their magnitude exceeds that of the conventional energy region by far and thus uncertainities in the corrective algorithms have a large effect,

Occupational exposure to lead is common in many industrial applications and hence it is of considerable medical interest to control the body-burden of lead in living man. More than 90 % of the lead in the body is concentrated in bone and hence in vivo measurements of the lead in the skeleton should give the most satisfactory way for estimating the body-burden. The routine method used today for checking on lead contamination is that of measurements on blood samples. However, since the concentration of lead in the blood is a sensitive function of the actual exposure conditions, this method provides only a poor indication of the total body-burden and the integrated lead exposure.

The method presented In 1976 for measuring stresses in polymeric materials including fiber-reinforced composites (1,2) yielded directly only one or two of the principal stresses and (elastic) strains in the embedded crystalline particles. The method is now extended so as to yield determinations of all three principal stresses σ1, σ2, σ3 and strains, ε1, ε2, ε3, The method applies to both residual and applied stresses and strains.

High angle diffractometry such as is used in ordinary X-ray stress determinations in metal objects is used, with suitable particles being embedded in a homogeneous plastic or reinforced composite before curing.

X-ray residual stress measurements have been made with a commercial portable X-ray diffraction apparatus that uses parallel beam optics and that was specifically designed for residual stress measurements. This machine differs from X-ray diffraction units using the usual parafocusing geometry in several respects, most notably reduced sample placement errors and larger sample sizes that can be accommodated. Two special modes of operation are available and will be discussed. These are the ability to use the side inclining method for stress analysis and the ability to use an oscillating ψ motion, the latter mode being useful for examining large grain size materials.

The angular dependent factors which affect the intensities of X-ray diffraction line profiles, as observed on a Standard X-ray diffractometer, are well established. They are the Lorentz factor, the polarization factor, the atomic scattering factor, and the temperature factor. For residual stress analysis, in which measurements are made at non-zero omega (psi) angles, an absorption factor must be added to this list. It is usual, however, in residual stress analysis, to omit two of these factors: the atomic scattering factor and the temperature factor. The omission of these two factors appreciably alters the change in the combined correction factor with change of diffraction angle. The proper angular dependent corrections are in the opposite sense to those customarily employed. The effect of the additional factors on measurements of residual stress are discussed.

Several factors have long been known to affect the intensity measurements of X-ray powder diffraction. The characterization of these effects has been impeded by difficulties in their isolation and the statistical nature of the data in which they manifest themselves. The most celebrated, and most detrimental, of the these effects is that of preferred orientation. This error can be eliminated with the spherical agglomeration of the sample (1). The spray drying process offers this result and is considered to have the broadest range of applicability to materials encountered by the powder diffractionist.

This is an introductory review of the physics and applications of low energy x-rays and electrons in the 10-1000 ev region. The basic interactions of these radiations within matter are discussed and typical de-excitation spectra, fluorescent x-ray and photoAuger electron, are presented. Specific examples of spectrographic methods and instruments for the low energy region are described as “based upon the use of long-spaced, Langmuir-Blodgett type of multilayers for ultrasoft x-ray analysis and the use of the hemispherical electrostatic analyzer for photo-Auger electron spectroscopy. Some examples of spectrographic signal, signal/background, and resolution are presented for applications to light element fluorescence, valence emission band, and photo-Auger electron analysis. The special aspects of the low energy x-ray analysis of high temperature plasmas and of x-ray astronomical sources in general are described.

Two proposed methods are described for obtaining the depth profiles (τ-profiles) of strains and stresses as a function of the 1/e penetration depth τ, using GIXD in the asymmetric geometry, without the need for layer removal. In the first, the ψ-method: ψ is varied, for a given reflection, while holding τ constant, by varying the wavelength λ and adjusting the incident angle α so as to maintain τ constant. This allows dϕ,ψ vs Sin2ψ plots to be obtained at constant τ. In the second, the ϕ-integral method: interplanar spacings dϕ,ψ are measured for ϕ values from 0 to 2π, at constant ψ and τ by holding α fixed. Two ψ values, i.e. two wavelengths, are needed to obtain the whole strain tensor, but if the sample is quasi-isotropic and the stress state is biaxial, only one wavelength is needed. A direct method is also described for obtaining the profiles as a function of depth z (z-profiles) from the corresponding τ-profiles using inverse Laplace transforms. Application of the method to the residual strain vs τ data of Doerner and Brennan for an Al film on Si is presented.

X-ray fractography is a new method utilizing the X-ray diffraction technique to observe the fracture surface for the analysis of the micro-mechanisms and mechanics of fracture.

In the present paper, X-ray fractography is applied to fracture surfaces of high strength aluminum alloy (JIS 7075-T6). The fracture toughness tests were conducted by using compact tension (CT) specimens with blunt notches and fatigue pre-cracks. The distribution of the residual stress near fracture surfaces was measured by the X-ray diffraction method. The effect of the notch radius on the fracture toughness value was discussed.

Traditionally, aluminum has been the most important raw metal material for the aerospace industry. Since the major part of aluminum production is consumed for aircraft, military, space, and other programs, sponsored or regulated by the U. S. Government, quality of various Al alloys is under governmental control. The representatives of the governmental agency are placed at each aluminum plant in order to assure a high quality of production on-site. A fast and reliable analytical method is essential to control the production process and to keep chemical composition of the alloys inside specified ranges.

Neutron diffraction has proved to be a useful tool for measuring residual and applied stresses in materials. Aspects of experimental design and methods for the mapping of complete triaxial stress tensors in a large component are discussed in the context of a comprehensive set of stress measurements made within the interior of the circumferential weld on a 0.91 m diameter cylinder. The cylinder is a subscale model of the casings for the Advanced Solid Rocket Motor being designed for the space shuttle. The subscale model was fabricated in order to characterize the residual stresses created in the welding process and to determine the effect of post weld heat treatment on the residual stresses. Control of the residual stresses in this application is necessary to eliminate possible problems with stress corrosion cracking in a salt water environment. Some illustrative results are also presented.

The results reviewed in this article were obtained by means of the ESCA technique at the Institute of Physics, University of Uppsala, Uppsala, Sweden and at the Department of Physics, Vanderbilt University, Nashville, Tennessee, USA.

The ESCA technique is basically the study of induced emission of photo and Auger electrons from a sample irradiated with x-rays. If the incident radiation is monochromatic (e.g. an x-ray emission line) the spectrum of these electrons gives precise information about the energy states of the electrons in the sample. To extract this information, high resolution electron spectroscopy is necessary. Instruments for such spectroscopy have therefore been extensively developed during the last decade.

Certain machining processes (e.g. turning, grinding, …) lead to a splitting up and an opening out of the curve of 2θ ϕ ψ = f (sin2ψ). In order to determine the complete stress tensor, it is necessary in this case to use the Dölle-Cohen method but this requires the knowledge of the diffraction angle 2θo for the unstressed material. Such a material, however, is extremely difficult to obtain in practice and the method usually employed uses annealed powder for this measurement. In our study, we show that it is nevertheless possible to determine the angle 2θo on a specimen for which the curve of 2θ ϕ ψ = f (sin2ψ) does not open out. Applying the Dölle-Cohen method to turning of a medium carbon steel, we have been able to bring to the fore: (i) the presence of an opening out of the curve 2θ ϕ ψ = f (sin2ψ), for measurements made in the direction of lay, which is attributed to a shear stress σ23, and (ii) shear stress σ12 which causes a rotation of the stress distribution diagram σϕ = f(ϕ) in the plane of the specimen.