The number of products that have to be inspected in pre-service and/or in service is increasing. Not only inspection for flaws are required increasingly, using the ordinary non-destructive testing, but also inspection of material characteristics, such as material strength evaluation and/or damage detection. For such inspection, X-ray diffraction has great possibilities as one of the most promising techniques, because it is (a) noncontact, (b) very sensitive to changes in parameters of the crystalline structure, and (c) suitable for surface observation.

In this paper, three topics are introduced which will be useful in the field of material strength evaluation and damage detection using X-ray diffraction.

Austempered ductile cast iron (ADI) lias microstructures that consist of martensite and of retained austenite. ADI has very toughness compared with cast iron heat-treated differently. The retained austenite near fracture surfaces transforms to martensite when fracture occurs.

In the present study, X-ray fraetography is applied to fatigue fracture surfaces of ADI. The fatigue tests were carried out on compact tension (CT) specimens. The volume fraction of retained austenite was measured quantitatively and the line broadening of X-ray diffraction profiles was measured on and beneath fatigue fracture surfaces. The depth of the plastic zone left on fracture surfaces was evaluated from line broadening. The results are discussed on the basis of fracture mechanics.

X-ray diffraction observation of metal fractures provides fracture analysis with useful information on the mechanisms and mechanical conditions of fracturing. This method is called “X-ray fractography” and has been developed especially in Japan as a new engineering tool for fracture analysis.

The residual stress measurement of quenched and tempered steels is of practical importance because the quenching can sometimes induce the high residual stress which affects the strength of materials. The stress constants of carbon steels quenched and tempered at various temperatures were measured in order to determine the residual stress of steels by x-ray diffraction. The stress constant increased slowly with increasing tempering temperatures below 500°C; it increased rapidly with tempering temperatures above about 500°C, This rapid increase in the stress constant is closely related to the change in microstructure of the steels in tempering; above the tempering temperature of around 500°C, the tempered martensite recrystallized and transformed to ferritic iron and fine cementite particles dispersed in the matrix; these coalesced and grew to be speroidized cementites and finally laminar cementite plates.

The electroplating of Cr has been an important industrial process for cutting tools, press machines and molds for casting. In spite of these, quite a few problems remain unsolved regarding the basic property. It is important to know the mechanical characteristics of Cr electroplated layers.

In the present paper, the first part deals with the measurement of mechanical Young's modulus of Cr electroplated layers. The X-ray method was successfully applied to measure the X-ray Young's modulus and the residual stress on the Cr electroplated surface layer.

For determination of stress in a localized area, we combined a modified single exposure technique and the imaging plate, which is an x-ray digital area detector. With the, single exposure method, stress value is obtained from lattice strains in two directions with a single incident x-ray beam directed at an oblique angle. However, since diffraction data around a whole Debye-Scherrer ring was used in this study, a stress value can be accurately determined in comparison with the single exposure method. We observed the DS ring by use of the imaging plate with requiring only a short exposure time. Lattice strains in many directions on a DS ring were measured by an image analyzer connected to a computer; we verified the effectiveness of this method.

Elastic modulus EI of crystalline regions of various high polymers in the direction parallel to the chain axis were measured using an X-ray diffraction method. The crystal deformation can be detected directly by the diffraction peak shift as a function of applied constant stress. The stress in the crystalline regions is assumed to be equal to that applied to the specimen. The validity of this assumption has been proven experimentally for polyethylene, poly(p-phenylene terephthalamide) and so on. The EI values were discussed in relation to molecular conformation and deformation mechanism of the chains.

The dependence of a peak diffraction angle on the positioning of the diffracted-beam Soller-slit pack was observed and studied by discussing the determining factors. In particular, the misalignment angle between the Soller pack and the counter axis is recognized as a key factor and experiments were performed for giving a quantitative basis to this statement. An important consequence of the results of these experiments and related profile analysis is the suggestion of designing parallel-beam diffractometers with the possibility of checking and changing the position of the diffracted-beam Soller-slit packs in order to optimize the performance of the instrument.

The analysis of linear dϕψ vs sin2ψ x-ray diffraction data in isotropic single phase materials was investigated for the evaluation of x-ray elastic constants. This study developed an experimental model for estimating x-ray elastic constants based on the analysis of biaxial residual stress states, A ball bearing steel and a 1018 steel weldment were evaluated.

In a second study, the measurement of residual stress gradients was evaluated for those depth ranges mat can not be evaluated with a single radiation. This requires various planes and radiation energies to obtain the simultaneous conditions of high diffraction angle and large x-ray penetration depth. The evaluation of the overlapped stress gradient region is illustrated in terms of x-ray energy and diffraction angle for the ease of iron. This analysis is specifically developed for the purpose of stress gradient measurement using synchrotron radiation.

HFIT is a program for the analysis of diffraction diagrams containing overlapping peak clusters. Profile functions have been implemented to analyze synchrotron diffraction data. It is written un Turbo C++ for PC operations. The analysis is done by operator interaction. The analysis is done on sections of the diffractogram containing a maximum of 2048 data points or 100 diffraction maxima. Special care is taken for smoothing the data and for the subtraction of background.

On the basis of the “column-like” powder model of Warren and Averbach, a profile fitting procedure was devised to obtain microstructural disorder parameters. The interference function

where d is the interplanar distance, λ the wavelength, θ the diffraction angle and N the number of cells within a column, was used to model experimental profiles taking into account the column-like crystallite size and r.m.s. strain distributions. The procedure can be applied both to single peak and to two or more peaks of multiple order of reflection. The method was tested on several samples, also having a bimodal size distribution, and the results compared with those obtained by the well-established Warren-Averbach analysis.

Nanocrystalline powders of Fe and W were prepared by mechanical working in a highenergy Spex 8000 mixer/mill. The diffraction patterns were recorded with Co Kα radiation and the line profiles were subjected to a Fourier analysis. The size 〈D〉 of the coherently diffracting domains (x-ray particle size) and the root-mean square strains 〈ε2L〉1/2 were determined with the Warren-Averbach method. In addition, the integral breadths were evaluated and corrected for instrumental broadening assuming Cauchy line profiles. In order to separate particle size and strains, the corrected breadths β(s) = βcosθ/λ were plotted as a function of s = 2sinθ/λ, i.e., β(s) =(1/D) + 2ε s, where D = 〈D2/〈D〉 and ε is a strain averaged over the domain size D.

X-ray fluorescence analysis indicated that the W powders contained an iron and chromium contamination due to the abrasion of the stainless steel balls reaching a value of 24 at% Fe+Cr after 20h of milling. Since W is elastically isotropic, all available (hkl) reflections can be used in the Warren-Averbach and line breaddi analyses. After 20 h of milling, the W powder exhibited a particle size 〈D〉 = 35 Å and a strain 〈ε2〉1/2 = 0.52% at L = 30 Å. The integral breadths yielded the particle size D1 = 70 Å and the strain ε = 0.38%. in the case of Fe powder, also milled for 20 h, the (110) - (220) pair of reflections was used to calculate the particle size and strains. The Fourier analysis yielded the values 〈D〉 = 105 Å and 〈ε2〉1/2 = 0.59% at L = 30 Å. The corresponding integral breadth values are D1 = 280 Å and ε1 = 0.7%. The sum of the particle size Fourier coefficients is equal to the integral breadth particle size D1 = 125 Å, which is very close to value 〈D〉 = 105 Å indicating that the particle or domain sizes have a very narrow size distribution.

X-ray diffraction (XRD) line-broadening analysis has been used to determine dislocation densities in zirconium alloys with hexagonal closepacked (hep) crystal structures and a complex distribution of dislocations reflecting the plastic, anisotropy of the material. The validity of the technique has been assessed by comparison with direct measurements of dislocation densities in deformed polycrystalline and neutron-irradiated single crystal material using transmission electron microscopy (TEM). The results show that-there is good agreement between the XRD and TEM for measurements on the deformed material whereas there is a large discrepancy for measurements on the irradiated single crystal; the XRD measurements significantly underestimating the TEM observations.

Ferroelectric polycrystalline thin films are being pursued as materials for use in the next generation of radiation hardened nonvolatile semiconductor memories, optical switches and optical computers. Of particular interest are PZT films with a composition near the morphotropic phase boundary. In order to fully understand the the difference in electrical properties as a function of processing parameters it is necessary to fully characterize phase composition and crystallographic properties of these films. Since some films are produced by either spinning or dipping successive layers to obtain the desired thickness it was necessary to compare the properties of each layer.

X-ray diffraction techniques employing parallel beam optics with grazing incidence angle geometry were used to characterize the films. Experimental procedures using sealed tube xray diffraction systems to determine differences in crystallite size and microstrain as a function of depth into the films are a rather unique application of this technique. Discerning the contribution to line broadening due to phase changes, grazing incident angle geometry, crystallite size and microstrain are key to the success of this technique.

This paper discusses the experimental techniques employed and will demonstrate how we were able to successfully determine microstrain as a function of depth into the film. We use transmission electron microscopy (TEM) to aid in the characterization of the films. A brief description of the processing procedures used to produce the films is also provided.

In this study electrolytic copper powder and atomised high purity iron powders of various size, fractions were consolidated to comparable densities by two very different processes (quasistatic pressing and dynamic, or shook wave, compaction). The resulting pairs of compacts had densities of approximately 0.96 of the theoretical density. These specimens were analysed by X-ray diffraction in order to determine the effect of particle size on the response to compaction.

The diffractometer instrumental profiles convoluted by Alexander from aberration profiles calculated using the methods developed Easterbrook, Pike and Wilson include two profiles which are not amenable to exact analytical solution. These two profiles are generated by the axial divergence and flat specimen aberrations. Using ray tracing techniques the exact profiles of these two aberrations have been computed for the Philips PW1050 and Scintag DA5 diffractometers. sample profiles at 2θ = 28°, 90° and 152° have been convoluted with the third asymmetric profile, that due to specimen transparency, and plots of the resultant profiles are shown. Shifts of the centroids and the peaks of the profiles from the true Bragg angle have also been computed and plotted over the range 2θ = 0°-180°.

Metallic filaments with sub-micrometer diameters have recently been fabricated using novel materials fabrication techniques at NRL. The specimens are enshrouded in a glass sheath and all efforts to obtain structural information from these samples with conventional x-ray sources have been negative. By using synchrotron radiation on a wiggler beam line, x-ray diffraction data have been obtained from samples with diameters of 0.22, 0.09, 0.07, and 0.04 μm. The two thicker samples were found to be single crystals with a structure consistent with that of normal Bi. Single crystal diffraction peaks obtained from the 0.07 μm sample are incompatible with the Bi-1 or any other known structure of Bi. We have provisionally identified this as Bi-X.

Real time observations of the YBa2Cu3O7-δ (123) melting process by high temperature XRD and optical microscopy reveal a reaction sequence which does not correspond well with the literature. CO2 gas, present in the air, reacts with 123 to produce the Y2CU2O5 phase. This reaction begins well below 800°C and persists up to 970°C when BaCuO2 begins to form. The previously unreported BaCuO2 reaction occurs in either air or oxygen and this phase grows at the expense of the 123 until both rapidly disappear at 1050°C with the appearance of Y2B2CuO5 (211), Formation of Y2O3 from the 211 melt occurs more slowly, beginning at 1150°C. Dynamic 00ℓ orientation has been observed at 950°C upon cooling from the melt. The orientationa) growth is believed to be a surface tension dependent, liquid assisted sintering reaction.

X-ray powder diffraction together with several other analytical techniques have been used to characterize the phase formation and the melt compositions associated with the invariant reactions in the system BaO-½Y2O3-CuOx. In this report, the characterization results of the ternary eutectic reaction of the system, the melting of the high Tc compound Ba2YCU3O6+x, and the melting of the 'green phase' BaY2CuO5 are described. The minimum malting eutectic temperature of the system has been determined to be ≈ 925°C, which corresponds to the reaction of Ba2YCu3O6+x + CuO + BaCuO2 → Liquid. The melting of Ba2YCu3O6+x takes place at around 1015°C to yield BaY2CuO5 + Liquid. The green phase melts around 1270°C to yield BaY2O4, Y2O3 and liquid. All these melts were found to contain only a small amount of Y. Reduction of the copper was found to accompany melting.

Aryloxyphenoxy propionates are a widely manufactured class of highly active grass-selective herbicides for use in various crops. Examples include VERDICT (1a), FUSILADE (1b), WHIP (1c), and ASSURE (1d). Figure 1 shows the general structure of aryloxyphenoxy propionates. All of these compounds contain a chiral center and each enantiomer of the optical pair exhibits significantly different herbicidal activity. The optically active isomers can be prepared by reacting the corresponding substituted phenoxyphenol with the S-(-)methyl lactate sulfonate ester (2). However, the optical yield from this type of reaction is usually less than 85%. Optical purification can be achieved by control of the crystallization.