Results of an experimental X-ray study on 96 synthetic glasses show that the 2θ positions of glass diffraction maxima have an inverse relation to SiO2 concentration in silicate glasses. This relationship is the basis of a new technique for semiquantitative determinations of SiOa in silicate materials by X-ray diffraction methods. Samples to be examined are fused and the resulting glass scanned from 12 to 40° 2θ using CiiKa radiation. The mean 2θ position of the diffraction maximum is a measure of the SiOs content of the glass. Calibration curves for both weight and molecular percent SiO2 vs. 2θ are presented in this report. The technique requires only small, unweighed amounts of sample for analysis ; it is simple, rapid, and utilizes standard diffraction equipment without modification. Its accuracy, at present, allows SiOa determinations to within ±1 to 4% of the actual concentration.

An extensive investigation of chemical composition, particle size, and surface area of copper-chromium oxide catalysts has been made. The two phases present in the activated material are copper oxide (CuO) and copper-chromium spinel (CuCr2O4). The crystallite size of the CuO phase (determined by X-ray diffraction line broadening) can be correlated with the catalytic activity measured on a CO-CO2 oxidation reaction. The catalytic activity of the oxide catalyst can be expressed as a function of the X-ray fluorescence intensity of the Cu Kα line even on changing the absolute copper concentration up to 3%. An attempt is made to explain this phenomenon by the heterogeneity effect caused by the difference in the linear absorption factors for the Cu Kα radiation in the system CuO-CuCr2O4.

Wires of 18 different metals were exploded in nitrogen by the discharge of a 20-μF capacitor bank charged to 10 kV. The resulting aerosols were collected under nitrogren on membrane e filters, which were mounted on glass slides and used directly in the sample holder of a recording X-ray diffractometer. The X-ray data were analyzed to determine the composition and approximate crystallite size of the particulates produced by the wire explosions in nitrogen and subsequent exposure to air.

Nitrides are found as reaction products from the explosion in nitrogen of aluminum, iron, indium, tantalum, thorium, uranium, tungsten, and zirconium. No nitrides were detected in the samples from cadmium, copper, magnesium, molybdenum, lead, and tin explosions, although such nitrides are known to exist; and the aerosols produced in nitrogen by the explosion of silver, gold, molybdenum, platinum, and tin consist almost entirely of metal particles. Oxides are attributed to contamination of the nitrogen or exposure of the samples to air.

Most of the crystallites observed are less than 1000 Å as determined from X-ray line broadening find confirmed in some instances by electron microscopy. For the UN2 and ThO2, crystallite sizes of the order of 130 Å and 50 Å, respectively, are observed. In samples comprised of a mixture of phases, the constituents usually have different mean crystallite sizes. The crystallite size is not affected dramatically by the ambient nitrogen pressure or voltage used.

Rat tail tendons were fixed in 4% formaldehyde at 250 g tension, soaked in nearly saturated solution of the amides involved, and dried while still under tension. X-ray diffraction patterns, taken with rotation around the collagen fiber axis, showed well-defined layer lines of the amide and usually substantial expansion of the collagen equatorial spacing.

The layer lines on collagen, in two cases on abnormal or polymorphic axes, are clustered around the number 4.86 ± 0.33 Å, or a figure twice this, implying the presence of a repeating hydro gen-bond accepting group such as the carbonyl group at this interval. The prominent collagen layer line at 9.4 Å is approximately double this interval.

This paper describes a technique of measuring the volume percent retained austenite in steel using ordinary filtered X-radiation and an X-ray diffractometer. As compared with conventional rate-meter recordings or microphotometer traces of diffraction peaks, the subject technique extends the range of austenite determinations from the usual 7 % down to 1 %. It markedly improves over the entire range of measurement.

Essentially, the technique consists of step scanning the profile of each selected martensite and austenite diffraction line and recording the corresponding intensity within a known probable error. The step-scanning, fixed-count, and counting-rate, recording operations are performed automatically by a counting-rate computer. The integrated intensity of each diffraction line is obtained by summation of intensity increments above background in accordance with the “trapezoidal rule.” For hardened steel, the best peak-to-background ratio is secured using filtered Cr Ka radiation with the vanadium filter located in the diffracted beam. The volume percent retained austenite is determined by direct comparison of the integrated intensity of an austenite line with the integrated intensity of a marten site line and from the relationships between intensity and concentration for the martensitic and austenitic phases.

An application of the subject technique was its use in determining the retained austenite behavior of carburized 9310 steel. The volume percent austenite retained on the surfaces of as-quenched specimens was determined as a function of carburizing potential. The amount of retained austenite subsequently transformed by various combinations of tempering, refrigerating, and retempering treatments was successively ascertained. The amount of retained austenite determined using the subject technique compared closely with the amount of retained austenite measured by metallographic examination. However, the reproducibility of results was better for the X-ray method as compared to metallographie examination. The nondestructive nature of the X-ray method permitted successive measurements on the same surface following repeated thermal treatments.

A versatile double-crystal X-ray spectrometer has been developed for the precise measurement of X-ray diffraction line widths to tenths of seconds. The device can be employed in either the parallel or antiparallel arrangement for rocking curve studies and can also be used in anomalous X-ray transmission experiments with nearly perfect crystals.

A detailed description of the instrument is given as well as some results concerning the Darwin theory of X-ray diffraction line widths and Borrmann effects.

To achieve increased case and precision of alignment, and to allow for convenient alteration between normal usage with filtered radiation and crystalmonochromated radiation, the G. E. goniometer has been mounted on milling machine beds allowing for x-y translation and 360° rotation; in addition the tube mount was repositioned. The usefulness of this apparatus has been demonstrated by accurately aligning the goniometer for usage with filtered radiation, with a new alignment procedure. As a demonstration of the accuracy and precision of alignment, the lattice parameter of silicon was determined from a powder sample. A least-squares analysis of the data gave a0 = 5.43046 Å with a standard deviation of ±0.00005 Å, in excellent agreement with the value of 5.43054 ± 0.00017 Å determined in a recent International Union of Crystallography test in many laboratories.

A monochromator housing has been built for use with all types of direct-beam monochromators and all radiations. This apparatus attaches to the new tube mount and was used to determine the optimum procedure for preparing the doubly bent LiF monochromator crystals designed by Warren to minimize the volume sampled in the reciprocal space of a single crystal. According to a suggestion made by Chipman, a doubly bent monochromator for use with poly crystalline specimens has been formed and its geometry and applications are presented. This monochromator gives about one-half as much intensity as that obtainable using filtered radiation and similar operating conditions ; this type of monochromator is therefore a powerful tool for use with powder specimens. A transmission diffracted-beam monochromator has also been constructed which attaches in a simple manner under the counter tube housing. Under similar operating conditions with a LiF monochromator, this yields intensities only one-tenth of those obtained using filtered radiation.

Several special-purpose attachments have been designed and built for the Siemens horizontal diffractometer. Design details and experimental results are shown for the following equipment: (1) Low-temperature mount for poly crystalline materials—examples are shown illustrating identification of organic liquids crystallized at low temperatures, and results are presented on coefficient of thermal expansion of alloys in the binary system copper—platinum from −185 to 25°C. (2) Low-temperature mount for single-crystal studies—this design allows recording of higher-level layer lines by use of a domed beryllium window. Illustrations are shown for organic single crystals and for organic liquids crystallized in the lowtemperature mount. (3) Focusing attachment—this attachment uses a curved specimen mounted on the focusing circle (Seeman-Bohlin mounting). Comparisons of dispersion are made and examples such as the (400) reflection from molybdenum are shown using both curved and flat specimens. (4) Full-circle goniometer—this device has been used primarily for determining distribution of intensity in amorphous and semicrystalline polymers, but is applicable to study of single crystals. Examples of both of these applications are discussed.

A single-crystal orienter for the Philips -wide-range goniometer is described. The orienter has a large (3.562 in.) carriage radius for convenient access. The carriage rides on twin V-ways ground accurate to ±0.0002 in. Carriage settings arid spindje settings can be made to 1′. The spindle mounts a standard goniometer head and translates to center the head arcs. An accessory collimator, beam trap, and scatter tube are described.

A new approach to X-ray absorption analysis is presented in this paper. The equation log (I2/I1) = KWA + KB is used, from which the weight fraction WA of a given element can be calculated in various solvents when only a calibration curve from one solvent and the absorption of the new solvent at two wavelengths (λ1 and λ2) are known.

This treatment uses the absorption at two wavelengths, one on each side of an absorption edge of the element under study. The desired wavelengths can be conveniently obtained from the Kα and Kβ radiation of an element with an atomic number just higher than the element under study. An easy way to accomplish this is to use the desired target element as the sample in an X-ray spectrometer. The Kα and Kβ radiations are then resolved with an appropriate analyzing crystal, and the absorption measurements are made consecutively.

The advantages of this approach are twofold. First, it is only necessary to do a full calibration curve in one solvent; calibration in other solvents can be calculated with only a knowledge of the absorption of that pure solvent at the wavelengths used, which can. either be determined experimentally or calculated. Secondly, the required experimental data can be collected very conveniently in an X-ray spectrometer.

The use of target current measurements in the electron microprobe for quantitative analysis of binary samples has been proposed by several authors. However, the equations proposed for calculations as well as instrumental conditions differ considerably. The present paper relates the target current measurements made with the Applied Research Laboratories microprobe to the backscatter coefficients determined independently. Equations for analyzing binary samples as well as applications to line scans and concentration mapping are given.

In interpreting X-ray intensity data from electron probe microanalyzers, the simplest approximation that can be made is that the X-ray intensity is a linear function of concentration. This linear relationship has been found to hold only in very limited cases. Where this simple relationship does not hold, it is generally assumed that increased concentration of an element is reflected in increased intensity of its characteristic X-ray lines. This assumption, which is always valid for binary samples, has been extremely useful, particularly for the interpretation of X-ray scanning pictures. However, in analyses based solely on observed X-ray intensities, large deviations from the linear relationship can make semiquantitative results misleading.

For multielement systems, the deviations from linearity result in ranges of concentration for each element within which increased concentration of the element does not result in an increase of its characteristic X-ray intensity. The magnitude of these deviations, and. hence the ranges of concentration, is related to the X-ray absorption and secondary fluorescence in the sample, which are in turn dependent on instrumental parameters such as X-ray take-off angle. Such inversions in the normal intensity-concentration relationship can result in gross misinterpretation of X-ray scanning pictures on even a qualitative basis. The various factors that lead to deviations from linearity are evaluated, and methods are given for correctly interpreting X-ray intensity data on a qualitative and semiquantitative basis.

Optical and electron metaliographic, X-ray diffraction, and electron microbeam probe studies of the interdiffusion of Cb-1 Zr alloy with type 316 stainless steel are reported. Extruded Cb-1 Zr alloy-type 316 stainless steel diffusion couples were heat treated at temperatures of 732, 871, 982, and 1093°C for time periods of US, 400, 900, 1400 hr. In no case was appreciable diffusion observed in specimens heat treated at 732°C for time periods chosen. Diffusion zones based on the systems iron-columbium and columbium-nickel-iron were observed in varying degrees in all other specimens. An activation energy for the rate-control ling process in the growth of the diffusion layers is reported. The growth rates of the observed zones were found to be retarded when these data were compared with data reported by other investigators for the interdiffusion of unalloyed columbiiim-type 316 stainless steel diffusion couples. Postulations arc made to explain this retarded growth rate and also to explain the growth of a nickel enriched columbium-iron-nickel-chromium intermetallic zone adjacent to the columbium.

The reliability and speed at which an analysis can be completed, using methods of the electron probe microanalyzer, depends to a large extent on the stability of the electron beam. The incident electron energy and total incident current must be maintained within prescribed limits to ensure accurate and reproducible X-ray data. The incident electron probe diameter must also stay within prescribed limits for maximum resolution over the analysis time. The performance of the electron optics is discussed in relation to high-voltage supply, current regulators, and filament supply. Methods for probe current stabilization using aperture sensing are discussed.

While conventional X-ray signal readout systems can be used in connection with the electron probe analyzer, new readout techniques can be applied with advantage, particularly for scanning procedures. Several novel techniques involving photographic recordings of oscilloscope tracings will be described. These techniques are applicable to area scanning (enhanced concentration method, concentration mapping with use of X-ray signals, and target current concentration mapping procedures) as well as line scanning. Combinations of area-scanning images with line-scan registration ate used for representing line-scan results.

By using operational amplifiers as signal adders, wavelength scans can be efficiently registered on a Polaroid photogram, with baseline indication and wavelength markers, in a single exposure. Another wavelength scanning technique registers the pulse height of the lines observed during the scanning operation, so that the order of reflection of the lines can be established. The use of an x-y recorder also offers advantages in the registration of line scans. Techniques for registration of multiple scans and for concentration mapping with the x-y recorder will be described.

Methods of quantitative electron probe analysis using empirical working curves have achieved only partial success because of variations in instrument design, analysis conditions, and homogeneity of standards. These problems have been solved for X-ray fluorescence analysis, but many of the more successful empirical methods cannot be used in electron probe analysis; instead, a more theoretical approach is indicated. In electron probe analysis quantitative results can be achieved with only pure elements as standards provided (1) the analysis conditions are carefully selected, (2) the observed intensities can be corrected to obtain the primary intensity actually produced in the specimen, and (3) the relationship of the primary intensity and concentration can be calculated. While present methods of making some of the corrections required improvement and a “universal” theory for relating the primary X-ray intensities to the concentrations still does not exist, the success achieved with this approach indicates that it should be used to the fullest extent before resorting to calibration curves. Moreover, as information is accumulated, the number of cases requiring the use of calibration curves should diminish, so that eventually it may be possible to perform quantitative analysis in any system with only pure elements as standards,

Recent studies have indicated only limited agreement between theoretically calculated X-ray absorption, fluorescence, and electron penetration correction factors and calibration curves obtained from alloy standards in binary systems. For some practical metallurgical problems, including diffusion gradient studies, intermediate phase identifications, etc., where analytical precision is required, alloy standards must be employed.

Most metallurgical investigations, however, are concerned with alloys containing a variety of elements. The use of theoretical calculations in these analyses is severely limited. At present, the precision of analyzed chemistries in such systems is somewhat poorer than the precision of the measured X-ray intensity values. Methods for applying combinations of theoretically calculated corrections, extrapolations from nominal alloy chemistries, etc. have been employed which yield reasonable analytical precisions but at best are first-order approximations. Approximate calculations for use in determining the chemistries of fine precipitates or inclusions where matrix excitation is unavoidable are also discussed.

The application of electron probe analysis to complex mineral systems has pointed out the great need for suitable standards. It is often difficult to obtain highly accurate analytical results on these complex systems using pure end members because of the large number of correction factors involved, particularly since some of these factors are not well known.

The requirements for electron probe standards are rather stringent. They must be well analyzed chemically, and be homogeneous on the micron level so that the small volume sampled by the probe is representative of bulk analysis. Unfortunately minerals suitable for standards are difficult to obtain. Minerals may appear to be single phases, but a careful microscopic examination will disclose that there are in fact two or more phases closely intergrown, so that the probe is not actually sampling a single phase. There are instances where the knowledge of homogeneity of the standards can only be obtained by an analytical tool like the electron probe. It is for reasons such as these that caution must be used in the selection of mineral standards. Because of the increasing use of the probe for mineral studies it has become desirable to establish a clearing house for well established standards and a comprehensive exchange program.

A compact, high-intensity pulsed soft X-ray system has been used to study the response characteristics of a plastic scintillation phosphor (NE-102). In particular, the decay characteristics of this phosphor plated on one surface with a thin (<1000 Å) layer of aluminum were investigated. Although, absolute calibration of the X-ray source had not been performed, estimates of X-ray scintillation efficiency were obtained, using two separate methods, which were in agreement to within a factor of two.

The primary purpose of this cursory program was to establish the validity of transferring calibration data from plated to unplated NE-102 scintillators employed in a photometric recording system. The results of the ensuing investigation indicated the equivalence of the two, but revealed several interesting and unsuspected phenomena. These were (1) an apparent scintillation light reflectance component of zero from the plated aluminum “mirror” surface, (2) a change in pulse waveform from electron beam input to scintillation light output, and (3) a 90-nsec delay between electron beam and photomultiplier signals. The methods employed in obtaining and verifying these data are subject to errors from uncertainty in the characteristics of several components employed in the experimental setup. These uncertainties and other measurement errors caused independent estimates of the external scintillation light efficiency to range from 0.1 to 0.2 %.

Other potential applications of a pulsed soft X-ray system to measurement problems in industry and research include dynamic studies in the fields of X-ray crystallography, instrumental methods of materials analysis, and radiography of low-density subjects.