The present work was performed on natural monocrystals from Mexico. All crystals presented well-formed natural faces of indices (01.2), (01.4), (11.3), and (00.1). They were reduced to magnetite in a thermobalance by heating at 1200°C under a pressure of 10−3 torr. The techniques used in the present work were Laue reflection diagrams and pole figures. The magnetite formed on the hematite showed preferential orientations of three different types. The mutual orientations of the two oxides all present a common zone axis for the lattices formed by the oxygen ions.

The technique analysing the cause and mechanism of fracture from the information obtained by X-ray irradiation on the fractured surface is called “X-ray fractography.” As a basic study of X-ray fractography the residual stress on the fatigue fractured surface and some parameters of the fracture mechanics were investigated.

In recent years, a number of experimental X-ray diffraction techniques have been developed by which a topographical display of the microscopical defects in a crystal can be obtained. This brief review of the most useful of these techniques is intended to summarize the elements of the various methods and to compare their respective features and limitations. Contrary to microradiographic methods, in which image contrast is due entirely to variations in X-ray absorption from point to point in the specimen, X-ray diffraction topography is concerned with point-topoint variations in the directions or the intensities of X-rays that have been diffracted by crystals. From these variations the defect structure of the crystal may be examined. Methods that mainly measure local variations in the direction of the diffracted beam are useful for the detection of gross misorientations such as subgrains or grains (methods of Gui nier and Tennevin, Schulz, Weissmann). Intensity mapping methods are chiefly concerned with individual defects such as dislocations, stacking faults, etc. In both groups there are experimental arrangements with both Laue-case (transmission) and Bragg-case (back reflection) geometry.

Critical to “Trace Analysis” measurement are the concepts of detection and quantification. Detection means positively identifying a chemical component. The term Minimum Detection Limit (MDL), used here, follows that of Currie, and is the smallest concentration that yields a net count, above system background, which will be detected with a 95% probability (with only a 5% probability of false detection).

During the past year the NORELCO Autrometer has been modified with respect to several details. Operation with the helium path and flow counter is now possible for work with the soft elements. Rotation in and out of the loading position is automatic so that all that an operator is required to do is to load the specimen holder. The sample or standard in the reading position can be rotated in its own plane for elimination of diffraction effects and other sample preparation problems. Other modifications in the electronics have increased the reliability and ease of maintenance in the production models, A description will be given of this latest unit and data will be presented on the results obtained both with respect to precision and analytical determinations.

Interest in the reference intensity ratio CRIR) method continues as a result of the potential capabilities of the technique for rapid multi-component quantitative analysis. The theoretical basis for the RIR technique is now well established (Chung, 1974; Hubbard et al., 1976; Davis, 1980, 1981; Davis and Johnson, 1982), Major areas for which the method can still be greatly improved include the methods used for sample preparation, the measurement of accurate intensities, and the use of an internally consistent set of reference intensity constants (designated RIR, or ki). In the methodology developed at the Institute of Atmospheric Sciences (IAS), South Dakota School of Mines and Technology, sample preparation centers about the suspension of the pulverized sample into an aerosol and collection onto filter media. Because of this step, intensities must be corrected from their raw values to intensities representative of “infinite thickness“ and volumetrically constant conditions of normal sample diffraction. The measurement and correction of intensities and sample preparation methodology is the subject matter of the present paper.

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.

A detector arrangement has been developed which will give nearly 100% efficiency over the entire range of wavelengths normally used in X-ray spectroscopy, including radiation from Mg Kα. A description of this counter is given and data obtained on pulse height distribution and pulse amplitudes will be discussed. Results obtained with typical specimens will be shown.

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.

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.

Microwave dielectric ceramics with high quality have received attention due to the rapid progress in microwave telecommunication and satellite broadcasting. The desirable properties in microwave dielectric resonators are a high dielectric constant (εr), low dielectric loss (tanδ) (i.e. high Q (Q =1/tanδ)), and low temperature coefficient of the resonant frequency(τf). Properties of dielectric ceramics in the TiO2-rich region of the BaO-Nd2O3-TiO2 ternary system (Fig. 1) were reported to have excellent dielectric constants, low dielectric losses and low temperature coefficients of capacitance by Kolar et al. (1978).

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.

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,

X-ray micro fluorescence imaging refers to the use of an x-ray beam as a probe to excite XRF in a specimen and produce a spatially resolved image of the element distribution. The advantages of high sensitivity and low background, together with the nondestructive nature of the measurement, have lead to applications of x-ray microfluorescence analysis in biology, geology, materials science, as well as in the area of nondestructive evaluation. Previous reports have described the development of an x-ray microprobe which uses a conventional source of x-rays to produce a 10-μm beam. This paper describes improvements to the microprobe which have increased the beam power and the solid angle of detection. The data collection and display software have also been enhanced.

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.

Despite the advances of the electron mtcrodiflraction technique, the determination of unit cells of microcrystalline compounds still depends in many cases on the interpretation of the X-ray powder pattern. The feasibility of this interpretation depends strongly un the precision of the data, the present-day level of which is far from its physical limit. It could be improved by application of monochromators in diflractometry. Some possible methods are discussed. With regard to interpretation, a survey of existing methods is given (Lipson, Ito, de Wolff, Szoldos). Some of these techniques are suitable for computers, at least in the initial phase of the procedure. This is illustrated by application of a zone-finding program for the complete solution of a given pattern. Finally, the influence of impurities and other disturbing factors is discussed.

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.

Machine parts made of ceramics are usually finished by grinding. Residual stresses as well as defects introduced by grinding will influence the fracture strength and the function of ceramics parts. Although several investigations used the X-ray diffraction method to measure the grinding residual stresses, their grinding conditions were rather limited.

In the present study, sintered alumina ceramics of 99% purity were ground with a resinoid diamond wheel (#140 grain size number) under various grinding conditions. The effects of depth of cut and stock removal on the residual stress was measured with the X-ray method.

With a new irradiation chamber a comparison of three excitation modes under same conditions and with the same material has been done. The results of this comparison are presented in the following manner: - Barltla scattering (graphite) versus Bragg reflection (HOPS) - Bragg reflection (Mo) versus secondary target fluorescence (Mo) - secondary target fluorescence (Sn) versus Barkla scattering (graphite) Excitation spectra and detection sensitivities of a NBS standard will be discussed for the different modes. The Barkla scattering was found to be the best excitation mode for a wide elemental range.

This paper describes a set of interactive computer programs written in FORTRAN IV and implemented on a POP 11/34 equipped with RLO-2 ten Mbyte discs and an RSX-11M operating system to assist in x-ray diffraction phase analysis. The packing of the data base will be described along with the various interactive programs that access it. The search/match package is designed more as a set of aids for the diffractionist rather than as a single totally automated search/match program, the procedure adapted by many of the xray diffraction (XRD) equipment manufacturers. The approach taken allows the analyst to direct the analysis procedure by utilizing different search/match programs or specifying various options within a given program.