An X-ray small-angle scattering instrument is described which is used for recording X-ray diffraction patterns or small-angle X-ray scattering curves in an angular region very close to the direct beam. The measurement of X-ray intensity is accomplished with standard geiger or scintillation counter techniques. The instrument is designed for use with a spot-focus or vertical-line X-ray source, In essence, it is a multiple-reflection double-crystal diffractometer, based on a concept developed by Bonse and Hart, employing two grooved perfect germanium crystals arranged in the parallel position. Multiple diffraction from these crystals produces a monochromated X-ray beam which can be several millimeters wide while still exhibiting extremely high angular resolution. As a result, effective sample volumes can be employed with maximum volume-to-thickness ratios. The principal features of the instrument are discussed with emphasis on the advantages of this device over those employing complex slit systems and film-re cording techniques, Data are presented to illustrate the operation, intensity, and resolution of the unit.

Residual elastic stresses have been measured in cold rolled α-brass (30% zinc) using the available x-ray diffractometer methods. Residual stress values obtained by the two exposure and sin2ψ methods of stress analysis are compared with data obtained using Wagner's extrapolation method.

For deformations up to 50% reduction in thickness, tensile surface stresses prevailed, and in most cases could be detected by these methods. Uncertainty of the value of a0, the lattice parameter of the deformed' material, presents a serious limitation to the extrapolation technique. Using the approximation a0 = a0ann, residual stresses appear lower than, and frequently of opposite sign to those given by the two exposure method. In addition, lattice parameter variations in the near surface regions of the rolled sheet were opposite to those expected from the true macrostress distributions shown to exist by the two exposure method and by strain gauge techniques. The distributions of ahkl points in the extrapolation plots were in agreement with theory for a combination of anisotropic elastic stresses and low stacking fault density.

X-ray powder diffraction (XRD) is widely used for qualitative analysis of the phases in multiphase mixtures. To extend the characterization to the level of quantitative analysis (QA) requires solution of many challenging problems such as elimination of preferred orientation (1,2,3); selection of an appropriate reference standard which closely matches the analyte phase in crystallite size, thermal history, stoichiometry etc. (4); effectively collecting the experimental intensities (5,6); and finally, performing the data reduction and analysis.

The desire to solve the last problem in a general way and to incorporate the “best” procedures developed in several laboratories into one package was one of the stimuli for developing the NBS*QUANT82 system of programs. This system is integrally coupled with the data collection system AUTO (6,7).

Recent advances in MOS integrated circuit technology have opened new, high-volume applications utilizing epitaxial silicon-on- insulating substrates. To provide good quality heteroepitaxial silicon films for the semiconductor industry, a development program has been established to improve both the crystalline quality and the fabrication techniques for the most promising current substrate, magnesium aluminum spinel.

The role of X-ray diffraction techniques in the investigation of crystal quality, substrate surface quality, and epitaxial film quality are discussed, and results interpreted as the program is traced from crystal growth to epitaxial film analysis.

An X-ray diffraction technique was used to measure residual stresses in Ti-6Al-4V and Ti-8Al-1Mo-1V sheet created by glass-bead peening, sand and aluminum oxide blasting, and a vibratory tumbling treatment. For peening and blasting, the use of larger particle sizes produced greater compressive stresses. In the case of the vibratory treatment, an increase in vibratory frequency or treatment time increased the compressive stress. Glass-bead peening caused a 10% reduction in yield strength while the other treatments had little effect on the tensile properties. Significant stress relaxation occurred in all the treated Ti-6Al-4V coupons exposed at 600° and 800°F.

This paper presents the theoretical and practical aspects of measuring residual stresses by X-ray diffraction with emphasis on the analysis of aluminum alloys. The theoretical considerations of radiation) beam geometry, and peak location will be discussed in regard to establishing optimum analysis techniques. The precision and reproducibility of this technique have been investigated so that results can be applied accurately. The approach, however, is basically a practical one, with the intent of studying residual stress systems as they affect engineering applications. Residual stress systems produced by thermal and mechanical treatments have been determined and the effect of treatment modifications and variations on the resultant stress system have been analyzed. The effect of operational variables such as time and temperature on the developed stress system are shown. From this, the merits of a particular treatment can be determined with respect to its intended application.

Analysis of solution heat-treated and quenched 2014 aluminum has shown a significant effect of the quench temperature on the resultant residual stress system. The results obtained from shot-peening this alloy are presented, as well as the effect of time and temperature on the shot-peened stress gradient.

Oxygen K-V (Kα) X-ray fluorescence spectra of MgO, Cu2O, CuO, La2CuO4, La2-xSrxCuO4, YBa2Cu3O7-x , and GdBa2Cu3O7-x are measured. The local (oxygen) and partial (2p) electron density of states (DOS) of these compounds are calculated by the cluster approximation with the discrete variational (DV) Hartree-Fock-Slater (Xα) method. The calculated O 2p DOS are compared with the measured X-ray fluorescence spectra. It is found that the measured 0 K-V X-ray fluorescence line shapes are well reproduced by the O 2p DOS calculated by a cluster including the second nearest neighbor atoms (oxygen atoms) in the solids. This indicates that the oxygen K-V X-ray emission spectra reflect the oxygen-oxygen orbital hybridization in the solid as well as the oxygen-metal orbital hybridization.

Much current solid-state research, particularly that concerning the Fermi surfaces of metals and semimetals, demands knowledge of lattice parameters at temperatures in the liquid-helium range. A helium cryostat diffraction apparatus that has been in continuous use at these temperatures will be described, and some new research results from it are presented. The results include measurements of the lattice constants for gallium and for indium, of interest because the axial ratio influences both the nuclear electric quadrupole spectrum and also the cyclotron resonance. Previous measurements have disclosed unusual expansion characteristics but have not extended below liquid-nitrogen temperature.

A second area in which the cryostat has been operating is the determination of the temperature of beginning recrystallization in high-purity metals that recrystallize at low temperatures. Experiments with zone-refined lead which has a recrystallization temperature near 160°K are reported.

Since first introduced by Claisse, twenty-five years ago, borate fusions have been used in XRF analysis of a wide variety of materials because fusion eliminates many of the problems associated with particle size and matrix effects encountered in the analysis of powders. Geological and environmental materials such as rocks, ores, sediments, slags, air-borne particulates, etc., lend themselves nicely to lithium or sodium tetraborate or lithium metaborate fusion because the inherent presence of silica in these materials stabilizes the resultant glass from crystallization.

The lattice misfits between γ and γ' phases in Ni-base superalloys (single crystal) were accurately determined for filings of specimens by using both a conventional X-ray tube focusing diffractometer(CXRFD) and a synchrotron-radiation parallel beam X-ray diffractometer (SRPXRD). All reflection peaks measured with the CXRFD were in a cluster of overlapping peaks because of the very small differences in the lattice parameters of both phases and the instrumental broadening due to X-ray optics including the spectral distribution of Xray source such as CuKα doublet. The deconvolution method was applied to remove the instrumental broadening from the peaks measured with the CXRFD. The window functions for the deconvolution method were calculated from CuKα doublet reflection of Si standard by a nonlinear least-square method.

The instrumental broadening of SRPXRD was much smaller than that of CXRFD since the monochromatic X-rays produced single peak profiles and constant profile shape over a wide 2θ range. A profile fitting with a pseudo-Voigt function was used to determine 2θ angles to 0.0005 deg. for the synchrotron powder data. The peak angle and shape reflected from γ' phases in γ-matrix and those fron electrochemically extracted γ'-phase were significantly different.

On-stream X-ray fluorescence analyzers have been available for about 20 years. They have been used with great success and they have made an effective process control possible in many concentrators. They have, however, one severe drawback. Normally the sample that ought to be measured is in slurry form and it would be difficult and expensive to prepare it into more conventional form used in ordinary laboratory practice. The main constituent of slurry is water and normally some kind of plastic film is needed to keep slurry apart from the measuring system at least when the slurry system is malfunctioning. Already these two things are sufficient to set a limit to the lightest element that can be measured with reasonable accuracy and precision. This means that minerals that contain only such low atomic number elements as e.g. Mg, Al, Si and P remain out of reach. Difficulties arise also in cases where the interesting element is not only in the solid material but also in the solution part of the slurry. In great many cases the interesting element occurs in several minerals at the same time which causes certain problems with the accuracy. Fortunately this problem does not set such a basic limitation as a too low Z does unless only one of these minerals is of interest, which may make the whole method worthless.

In the X-ray fluorescence analysis of homogeneous specimens, the correlation between the characteristic line intensity of an analyte element and the concentration of that element, is typically non-linear over wide concentration ranges, due to interelement effects between the analyte element and other elements making up the specimen matrix. Although in many cases limiting the analyte concentration range may allow the use of linear calibration curves based on type-standardisation, it is usually more desirable to work with general purpose calibration schemes which are applicable to a variety of matrix types over wide concentration ranges.

This paper briefly traces the study of the preprecipitation or cold-aging stage of the decomposition of supersaturated solutions by means of diffuse scattering of X-rays.

This part of the overall precipitation process is of considerable practical as well as theoretical interest because it is during preprecipitation that changes in many physical and mechanical properties take place without the formation of a precipitate phase.

Examples will be given to show the types of zones encountered during this stage in various age-hardening alloys. These will attempt to illustrate the contribution which the study of diffuse scattering of X-rays, guided by present-day concepts of crystal imperfections, has made toward a better understanding of the precipitation process in alloys.

During the course of catalytic experiments on bulk copper single crystals, several crystals were intentionally oxidized to form thick (6000 Å) Cu2O films on the copper substrates. These oxidized crystals were investigated by means of a high temperature chamber installed on a General Electric XRD-5 X-ray diffractometer. It was discovered subsequently that the lattice spacings of the Cu2O decreased upon heating and increased upon cooling. Bulk single crystals and polycrystals of copper were oxidized at 3 Torr of air for several hours. All of the oxidized crystals were examined with copper and chromium radiation and both showed similar results. Typical of the results was an oxidized (110) copper disc which showed a net contraction upon heating of 1% for the (110) Cu2O planes. This slightly oriented Cu2O film was distinguished because -it contracted on heating to 440°C from room temperature, then expanded from 440°-540°C, and then expanded again when cooled from 540°C to room temperature. CuO also was detected in the diffraction pattern and the CuO and copper spacings were behaving normally with the temperature changes. A polycrystal of Cu2O was'examined and that, of course, also acted normally as its temperature was varied. Borie and co-workers have reported and explained very nicely similar anomalous behavior for thinner (500 Å) (110) oriented Cu2O films grown on (110) copper substrates. They showed that the epitaxial forces would cause an oxide film grown at high temperatures to contract parallel to the metal interface and expand normal to the interface as the copper cools and contracts. The oxide would expand normal to the surface in. order to keep its unit cell volume constant.

It is felt that epitaxial forces are not causing the anomalous behavior in the present work mainly because the 6000 Å of Cu2O is too thick for epitaxy to exert a meaningful force. The oxide film on the (110) copper was slightly (110) oriented but all of the Cu2O reflections behaved similarly. An additional reason to discount epitaxy is that this Cu2O film expanded upon heating from 440°-540°C. For these thick oxide films epitaxial forces do not seem to be the controlling factor; therefore, a point defect mechanism must be the cause. Changing oxidation and diffusion rates with temperature would produce various vacancy concentrations in the oxide layer and cause the spacings to vary.

In view of the importance of obtaining optimum conditions for the X-ray fluorescence analysis of light elements, an investigation has been made of the effects of varying the X-ray tube target, the target take-off angle, the tube voltage, and the tube window thickness. The effects of these parameters have been observed by measurement of the intensity of fluorescence of two light elements using the Ray max 60 demountable tube and vacuum path spectrometer. The results obtained are compared with those given by theoretical calculations based on consideration of the relevant parameters; good qualitative agreement has been obtained. It is shown that a high primary X-ray intensity is obtained with a high target take-off angle, a low angle of incidence of the electron beam on the target, and an optimum setting of tube voltage. It is further shown that the most suitable target to use for the fluorescence analysis of light elements is markedly dependent on the thickness of the X-ray tube window.

Measurements have been made on the FeLII/LIII intensity ratio on oxide free iron surface produced by evaporating a 50 Å Ti film on iron. These results show that the reported increase in the FeLII/LIII ratio with decreasing accelerating voltages is due largely to surface oxide and not self absorption. Also, for the vacuum presently used by soft x-ray spectroscopists the oxide surface on metals contribute strongly to the soft x-ray spectra of the bulk material for accelerating voltages below 4 kV.

The production of standard x-ray diffraction patterns at NBS imposes special requirements in the data processing of powder patterns. The patterns should be complete and have an overall accuracy of better than 0.01 degree two theta. To ensure completeness all the observable peaks should be indexed. To make certain that the sample is a pure phase, weak peaks have to be identified as well.

The indexing of all the peaks implies that the cell constants must be known and there should be a good agreement between all the calculated and observed peak positions. In practice this is achieved by a least-squares refinement of the unit cell parameters. This serves as a test of the assumed unit cell and also as an interpretation of the observed peaks. Finally, an attempt is made to identify the space group. This step also requires the identification of weak peaks. The agreement of a known space group with the observed reflections further confirms the purity of the sample.

Elemental analyses of geologic materials were obtained using X-ray microfluorescence combined with simultaneous elemental digital mapping. The analytical results corroborate the information obtained by electron and optical microscopy methods. Zoned garnet and ore deposit specimens were analyzed and compared to information obtained from other analytical methods. The penetrating nature of the X-ray beam using this method provides elemental information from beneath the sample surface. The combination of this depth information with the surface information supplied by electron microscopy provides a more complete analysis of the sample than is possible with each technique alone. Minimal or no sample preparation along with the ability to examine materials in air enhances the microfluorescence and digital mapping analysis technique.

Fluorescent x-ray speorographic studies of mineral systems were begun in the Metallurgy Division of the Denver Research Institute in 1953. These studies were concerned with several techniques but the primary research emphasis was placed on a method involving conjunctive analyses by monochromatic x-ray absorptiometry and fluorescent x-ray spectrography.

Experimental data for mineral systems with wide variations in matrix compositions exhibit departures from simple calibration curves relating intensity and concentration for an element in a series of samples analyzed by simple fluorescent x-ray spectrographic procedures.

Absorptiometric measurements are made with a thin layer of the mineral sample as an absorption filter for the monochromatic x-rays emitted by the element in question. The results of these measurements provide information for improvement of the simple correlation of intensity and concentration by manipulation of the experimental data with various operations based on Beer's law of radiation absorption.

The results of work at the Denver Research Institute indicated the feasibility of the fluorescent x-ray spectrographic-absorptiometric method and the current work is an extension of the study of basic fundamentals, mechanical factors and practical applications of the technique.

Analysis of sample composition and/or thickness in a routine, process-control or monitoring environment generally requires rapid turn-around time with minimal sample handling. X-ray Fluorescence (XRF) is well-suited for these kinds of analyses and has been applied to various bulk and thin sample applications (1-7). This technique is rapid, precise, non-destructive, and requires minimal sample handling.

X-ray Fluorescence is generally considered a secondary analysis technique, that is, instrumentation must be calibrated using known standards before unknown samples may be analyzed (quantitative analysis). Continuing work on standardless approaches, particularly for Energy-Dispersive XRF (EOXRF) systems, relax this requirement for some samples but the large share of XRF analyses still require calibration with standards. A number of mathematical and non-matheraatical techniques have been devised to calibrate XRF measurements for many different sample types (1,2,8,9).