Fracture accidents of engineering structures and machines in operation sometimes result from defects. One of the purposes of fracture analysis are to determine the causes of failure, and to use the information to prevent similar failure accidents. It is important to obtain quantitative analysis from the fracture surface. X-ray diffraction technique as well as Electron Fraotography has been widely used for fracture analysis of engineering structures and machines.

We report the implementation of two new methods of accurate comparison of lattice parameters against a silicon standard using a high resolution X-ray diffractometer. The double axis method uses a specimen rotation stage which set the limit of reproducibility (at 3 sigma) to 3 parts in 105. An application of the technique is illustrated in measurements of the zinc concentration in Cd1-xZnx Te to an accuracy of 0.1%. The triple axis technique uses beam conditioner and analyser crystals to define the incident and diffracted wave vectors. In measurement of the lattice parameters of InAs, we found a precision of 1 part in 105 and traceable accuracy of a several parts in 105.

In this paper, the application of recently developed x-ray diffraction techniques to the characterization of thin epitaxial films will be discussed. The double-crystal diffractometer, with high resolution in the non-dispersive arrangement, enables the materials scientist to study epitaxial systems having a very small mismatch with high precision. A key part of the characterization of an epitaxial film is the determination of the strain tensor by measuring lattice spacing! in various directions The determination of strain and composition profiles in ion-implanted films, epitaxial layers and superlattices by rocking-curve analysis will also be reviewed. Grazingincidence diffraction, an emerging new technique, can be used to obtain structural details parallel to the interface on films with thicknesses ranging down to a few atomic layers. The synchroton has now become increasingly available as a powerful source of x radiation which will facilitate the application of conventional and grazing-incidence diffraction to ultra-thin films.

Intrinsic stresses as a function of σ, the 1/e penetration depth were measured for a smooth, 1μm thick, fine grained, cylindrical post magnetron sputtered molybdenum film deposited on a vycor glass substrate in the dynamic deposition mode. Using grazing incidence diffraction and the Mo (321) reflection, lattice spacing profiles were determined for τ values from 200-4400 Å. The in-plane intrinsic stresses parallel and perpendicular to the post axis were determined employing the ϕ-integral method and assuming elastic isotropy. The results were related to the surface structure and composition profiles via atomic force microscopy (AFM) and auger electron spectroscopy (AES) respectively.

Various industries throughout the world require Standard methods for trade of products and referee analysis. Over the past 20-30 years, a number of wet-chemical Standard methods have been developed and are in use. Due to the large number of elements required for analysis in most products, XRF methods have become attractive as techniques to handle many elements simultaneously with a simple single sample preparation. Despite XRF being in daily use in many industries as an ‘in-house’ method, there are relatively few National or International Standard XRF methods.

Small-angle X-ray scattering measurements were made on samples of CaO—MgO—SiO2 as CaO-MgO-SiO2 glass in which met astable amorphous phase separation had been induced by heat treatment. Glass rods drawn from a melt of composition 30.5% CaO, 8.0% MgO, 61.5% SiO2 (by weight) at 1400°C were heat treated for 1, 2, 10, and 15hr at 825°C. X-ray scattering intensities of heat-treated and non-heat-treated samples were measured using an apparatus based on Kratky collimation geometry and equipped with a pulse height analyzer. Particle sizes were calculated from the radii of gyration which were determined from plots of log intensity vs, θ2, according to the method of Guinier. The data show a growth with time of the dispersed spheres from 350 to 1880 Å in diameter and correspond to the growth rate for diffusion-controlled growth of a sphere. Electron micrographs of identical samples prepared concurrently are presented. Inhomogeneity sizes obtained by the two methods are in very good agreement. Results obtained using the Kratky system in conjunction with a pulse height analyzer are compared with those obtained when a slit collimation system and balanced filter monochronmtization were used to study the same sample.

The residual stress left on the fracture surface is one of the important parameters in X-ray fractographic study. It has been used to analyze fracture mechanisms in fracture toughness and fatigue tests especially of high strength steels.

In this paper, X-ray fractography was applied to brittle fracture of alumina (Al2O3) and zirconia (ZΓO2) ceramics.

Equipment is described whereby comparative measurements were made on the relative absorption of air.helium, and vacuum for the softer radiations which are of interest in furthering the range of sensitivities of the X-ray spectrograph. Data on magnesium, aluminum, and silicon and shorter wavelengths are presented.

The X-ray diffraction method was used to measure the triaxial state of residual stresses in each phase in the following four kinds of composites; ZrO2/Al2O3 composite, WC-Co alloy, SiC/Al-alloy composite, and TiC/SiC coating. The residual macrostress and microstress were determined from the phase stresses by using the rule of mixture. The effects of heat treatment and surface finishing on the residual stress were studied. The measured value of the thermal residual stress was compared with the theoretical prediction based on the mismatch of the coefficient of thermal expansion.

External X-ray total reflection occurs when collimated X-ray beams impinge on a smooth, flat surface of matter at a small glancing angle, typically a few mrad. With respect to the X-ray fluorescence technique, total reflection experiments have allowed the trace determination of solution samples using an X-ray mirror as a sample support. The grazing incidence X-ray fluorescence technique (GIF) is also suitable for near-surface element analysis of the material, because the penetration depth of X-rays is 10-1000 Å around the critical angle.

The error introduced by sample scattering in EDXRF analysis is evaluated by Monte Carlo simulation. This is accomplished by deriving a Monte Carlo model capable of simulating single Compton and Rayleigh scatters from the exciting photon source and from fluorescent X rays in homogeneous samples. The model also includes primary, secondary, and tertiary fluorescence events. (1) Results are given for Ni-Fe-Cr ternary samples for various exciting energies with and without scattering and indicate that errors as large as 2% can be attributed to this effect.

The residual stress left on the fracture surface is one of the important parameters in X-ray fractography and has been used to analyze fracture mechanisms in fracture toughness and fatigue tests especially of high strength steels.

In the present paper, the distribution of residual stress beneath the fracture surface made by stress corrosion cracking was measured by the X-ray diffraction method. Stress corrosion cracking tests were conducted by using compact tension specimens of 200°C tempered AISI steel in 3.5% NaCl solution environment under various electrode potentials. The effect of electrode potential on the growth kinetics of stress corrosion cracking is discussed on the basis of residual stress distribution.

Techniques for the computer-assisted evaluation of crystallographic data have been developed to improve the data compilations of the NBS Crystal Data Center and the JCPDS—International Centre for Diffraction Data. The resulting computer program, NBS*ATDS80, can be used for the analysis of unit-cell and powder data by the general scientific community as well. NBS*AIDS80 is written in FORTRAN to permit implementation on a wide variety of computers, and input may be from cards or from a terminal. The research and analysis components that will be of use to the individual scientist include the following:

• 1) Calculation of the Crystal Data cell, determinative ratios, and space group for the comparison and reporting of unit cell parameters in a standard setting and for the identification of unknowns.

• 2) Determination of the reduced cell, reduced form number, and the unit cell with the highest metric symmetry.

• 3) Calculation of the molecular weight from the formula using the most recent atomic weights, and comparison of the density calculated by the program with the measured density.

• 4) Generation of d-spacings and indices for any input cell and crystal system.

• 5) Comparison of input powder data with calculated d-spacings, indexing of lines based on known unit cell parameters, and calculation of figures of merit.

Computed tomography (CT), commonly known as CAT scanning (computerized axial tomography), is a technology that produces an image of the internaI structure of a cross sectional slice through an object via the reconstruction of a matrix of X-ray attenuation coefficients. This non-destructive method is fast (50 ms to 7 min per image depending on the technological generation of the instrument) and requires minimal sample preparation. Images are generated from digital computations, and instruments essentially have a linear response. This allows quantitative estimations of density variations, dimensions and areas directly from console displays.

The growing need for multielement analytical capability is currently being emphasized by the ever broadening governmental regulations on metallic pollutants in water sources. These new regulations cover more elements and are more restrictive in the type and amounts allowable in waste water and natural sources. For example, the California Public Health Law of 1970 states that 0.01 ppm arsenic, 1.0 ppm barium, 0.01 cadmium, 0.05 ppm manganese and 5.0 ppm zinc are the limiting concentrations of these elements in drinking water. Monitoring programs, both for compliance-enforcement and general survey work, have become a greater burden on both governmental agencies and private inductries. While trace analysis in solutions presents certain difficulties to the analytical chemist, regardless of the technique used, the results of this study indicate that x-ray analysis provides a more useful analytical tool for routine work and offers multielement capability with minimal sample preparation.

The determination of the orientation of a single crystal by Laue X-ray photographs is dependent on the identification of the indices of the spots. At the present time, the determination of indices is done by various methods, none of which is entirely systematical. A method for establishing the indices of the spots which avoids a trial-and-error approach is described here. The method is graphical, uses a specially compiled table of erystallographic angles and is not dependent on the complexity of the structure of the crystal or its symmetry. An example of the cubic system is included. With more complex crystal structures the method becomes very laborious and the help of computer methods is suggested.

X-ray stress analyses were performed on seven (7) nickel-plated camshafts from helicopter transmissions. The purpose of this investigation was to determine if this residual stress technique was useful in determining the state of stress in load-bearing plated surfaces of critical reworked aircraft components. Specifically, it was desired to characterize six different stages of nickel plating processing. These were: as-plated, plated and baked, machined, machined and baked, ground, and ground and baked. Three different radiation wavelengths with different penetrations were used In this investigation. CrKα , CoKα , and CuKα, radiations were each used on all of the camshafts. These wavelengths were selected to determine if there were stress gradients in the plated layers. This paper presents and discusses the results of these studies.

There are three factors which may influence the method by which a piece of evidence is analyzed in a forensic laboratory. The first stems from the definition of the word forensic. It means ”… pertaining to, connected with, or used in the courts of law…” The major areas of forensic analysis are criminal, regulatory, and civil. The purpose of an analysis may be to aid in the prosecution or defense of criminal charges, to determine if a product meets its statutory requirements, to satisfy a consumer complaint, or to determine liability. For these reasons the legal aspects of an analysis may often put constraints upon the analyst. These may require special handling or documentation procedures.

In the measurement of residual stresses in hardened carbon steels by X-ray diffraction the principal difficulty encountered is determining the precise location of the broad diffraction lines. Christenson and RowlandM have proposed a workable technique, but it entails a complicated correction calculation. A simplified correction procedure, based on theoretical considerations, will be described which shortens the time required to obtain accurate data and cuts the time required for calculation to a fraction of that required for the previous method.

It can be shown that the asymmetry of the broad diffraction lines in the back reflection region is largely due to 6 dependent intensity factors. Thus, the proposed correction procedure uses a multiplicative correction to peak intensity which includes all significant geometrical and absorption factors. The line position is then determined accurately as the axis of a parabola fitted to the corrected data. Since the data is taken in the vicinity of the peak, the time required to obtain accurate data is reduced and furthermore it is possible to determine residual stresses in as-quenched steel even though the structure is tetragonal.

Examples of the type of stresses measured and the correlation between this new method and that of Christenson and Rowland will be presented.

The advent of computer automation and profile fitting techniques in powder diffraction., along with a general solution to the problem of preferred orientation, has opened a series of new horizons for this method. The new levels of accuracy attainable have brought us to the threshold of routine reliable qualitative phase identification, high precision quantitative analysis and the ability to perform crystal structure analysis on some of the most important technological materials. It has been primarily the question of accuracy which has held up these developments until now.