Machined parts made of fine ceramics are usually finished by grinding (Yajima et al.,1990, Mishima et al.,1987). The residual stress introduced by grinding will influence the fracture strength and the function of ceramics, and needs further consideration. Over the past few years, a considerable number of studies have evaluated ground ceramics by means of the X-ray method. However, it is well known that X-ray stress measuring data, 2 θ φ φ-sin2 φ curves of the surface layer of the unidirectionally machined ceramics are showing non-linear behavior (Kishimoto et al.,1987) . In this case, the sin2 φ method is inadequate for the evaluation of the stress (Sasaki et al.,1989).

Residual stress is inevitably introduced into composites because of the mismatch of the coefficient of thermal expansion, and it is different for each phase. The x-ray method can detect separately the stress in each phase, so will yield useful information for analyzing the toughening mechanisms of composites.

Austempered ductile cast iron (ADI) has composite microstructures, which are martensite/retained austenite structures. ADI has very large toughness compared to other ductile cast irons. After fracture, the retained austenite near the fracture surface will be transformed to martensite. In the present study, X-ray fractography is applied to fatigue fracture surface of ADI. The fatigue tests were carried out on compact tension (CT) specimens. The volume fraction of retained austenite was quantitatively measured on and beneath fatigue fracture surfaces. The plastic strain on the fracture surface was estimated from measuring the line broadening of X-ray diffraction profiles. The depth of the plastic zone left on fracture surface was evaluated from the distributions of the volume fraction of retained austenite. The results are discussed on the basis of fracture mechanics.

Titanium aluminide base allays are new materials of interest with exellent potential for high temperature structural applications. Several studies on the fracture toughness of these alloys have been reported and the beneficial effect of lamellar microstructure consisting of Ti3Al(α2) and TiAl(γ) has been detected. While these studies indicate such an enhancement of the fracture toughness is caused by micro-crack toughening, SEM observation alone is insufficient to clarify the fracture mechanism.

A project was undertaken to compare the Williamson-Hall and Fourier teclrniques for analyzing particle-size and micro-strain induced x-ray line profile broadening. The four alumina powders analyzed in the study were the candidates from which SRM 676, a quantitative analysis Standard Reference Material, was chosen. SRM 660 (LaB6) was used to determine the instrument profile function, IPF. However, difficulty was encountered in fitting an appropriate mathematical model to the IPF data; this prevented the application of Fourier analysis methods and restricted the number of profiles that could be analyzed with the Williamson-Hall method. The size/stain data compared favorably with other microstructural data collected on these specimens.

X-ray line broadening is caused by variations in lattice strain and small particle size. When hydrogen is introduced into the steel by the electrolytica! method, structural changes are observed. X-ray line broadening is a suitable measurement in such cases. The Warren and Averbach Fourier analysis is a good method for line broadening studies. In this method, strain and particle size effects can be separated because broadening due to particle size is independent of order of the diffraction peaks, while broadening due to strain is not.

Different diffraction patterns were compared one to the other in order to evaluate the contribution of different effects: Thus, in order to arrive at observing true differences between the patterns, “Diffraction Instrumental Monitoring” was adopted to assess reproducibility, stability, as well as differences in the instrumentation set up. To this end aberrations affecting peaks centroid position and variance were taken into account, Moreover the variation of variance of single peaks was analysed to achieve information on microcrystalline properties of real crystalline lattices.

Two-dimensional detectors utilized in x-ray diffraction studies are described. Film, image intensifier/CCD camera, two-dimensional position-sensitive area, and photostimulable storage phosphor detectors are compared. The storage phosphor detector was found to be well suited for analysis of oriented semicrystalline polyester films. Quantitation of polymer orientation was determined using the Hermans orientation distribution function.

Position-sensitive detectors (PSD's) are commonly available for X-ray diffraction, where they are used in the angle dispersive mode at fixed wavelength λ. They are sensitive to the scattering angle 2Θ. The resolution of such instruments is determined by the physical properties of the detector, and, of course, the distance from the sample. Using continuous radiation solid state detectors (Ge, Ge(Li), Si(Li)) are sensitive to energy (equivalent to λ) at fixed scattering angle 2Θo, They are being used for X-rays, especially with synchrotron radiation. Because X-rays travel with the speed of light, those two techniques cannot be combined. Thermal neutrons, on the other hand, are comparatively slowly traveling particles (2200 m/s at 300 K) and consequently time-of-flight (TOF) instruments with choppers at continuous neutron beams are known for a long time; they are being used as well for diff-actomet! y as for inelastic scattering.

A X-ray diffraction system using an Imaging Plate(IP) has been developed for time resolved X-ray measurements. The system consists of a new drum scanning type IP reader which includes a multiple time resolved X-ray exposure mechanism and a simple high temperature sample holder. Both are controlled from a personal computer. The new IP reader also supports 50μm/pixel reading for high resolution type IP (Blue IP), and has a spatial resolution better than 75μm.

The variability of adhesion promoter (primer) film thickness has been identified at Ford Motor Company as an important factor in maintaining the quality of paint on exterior plastic body parts. XRF offers unique advantages for non-destructive film monitoring. Monitoring of large parts for process control requires a non-contact approach using a small mobile probe. Previous attempts to implement a practical XRF gauging probe have been hampered by the choice of available x-ray detection technologies; proportional counters cannot resolve the layer's fluorescent lines properly and suffer from instability, while Si(Li) or Ge detectors need cooling to low temperatures, which makes their usage impractical for mobile probe.

The recent commercial availability of state-of-the-art Mercuric Iodide (HgI2) x-ray detectors led to the development of a lightweight XRF probe that contains an x-ray tube and a HgI2 detector. Thickness measurements of primer films on plastic substrates were characterized, and 15 sec. acquisition yielded precision of 0.225 and 0.525 pm for film thicknesses of 5 and 20 µm respectively. Ti was added to the substrate and Cr to the film as tagging elements. A ratiometric technique, taking into account absorption of the Ti signal in the film, yields excellent linearity and compensates for instrumental errors such as sampleto- probe distance variation and x-ray source fluctuations.

A new x-ray spectrometer has been constructed which incorporates a novel large area, low capacitance Si(Li) detector and a low noise JFET (junction field effect transistor) preamplifier. The spectrometer operates at high count Tates without the conventional compromise in energy resolution. For example, at an amplifier peaking time of 1 p.sec and a throughput count rate of 145,000 counts sec-1, the energy resolution at 5.9 keV is 220 eV FWHM. Commercially available spectrometers utilizing conventional geometry Si(Li) detectors with areas equivalent to the new detector have resolutions on the order of 540 eV under the same conditions. Conventional x-ray spectrometers offering high energy resolution must employ detectors with areas one-tenth the size of the new LBL detector (20 mm2 compared with 200 mm2). However, even with the use of the smaller area detectors, the energy resolution of a commercial system is typically limited to approximately 300 eV (again, at 1 μsec and 5.9 keV) due to the noise of the commercially available JFET's. The new large area detector is useful in high count rate applications, but is also useful in the detection of weak photon signals, in which it is desirable to subtend as large an angle of the available photon flux as possible, while still maintaining excellent energy resolution. X-ray fluorescence data from die new spectrometer is shown in comparison to a commercially available system in the analysis of a dilute muhi-element material, and also in conjunction with high count rate synchrotron EXAFS applications.

An ultra-high vacuum chamber designed for in situ grazing incidence small angle x-ray scattering (GISAXS) surface analysis is described. Unique features of this equipment are the precision rotary feedthrough for angular alignment of the sample, the sample heating design, the Be window arrangement, and the compatibility of this chamber with both a rotating anode and a synchrotron beamline. This chamber was used as part of a GISAXS camera utilizing a 18 kW Rigaku rotating anode, pin-hole collimation, and a position sensitive detector. The resolution of this camera was 0.007 A-1 with a 1.4 mm wide beamstop and CuKα

Modern synchrotron sources, and recent developments in experimental techniques, are allowing significant: progress to be made at present in the quality of crystal-structure infonnation at high pressure. Though there are exciting prospects for single-crystal work, especially using Laue techniques, most of the recent advances have been made in powder diffraction. In any case, high-pressure diffraction studies often require powder techniques because single crystals fail to survive the large density changes that accompany many pressure-induced phase transitions. In this paper, we focus on angle-dispersive (AD) powder diffraction on synchrotron sources.

The days of Debye-Scherrer film as a recording medium for X-ray powder patterns are all but gone with the development of precise, high sensitivity diffractometer systems. However, film does present some advantages over diffractometry (digital positioning and recording) for certain applications, A scanning densitometer system is described which totally automates the analysis of Debye-Scherrer film. It is much more precise and more capable than the simple line readers available in the past and can reduce the analysis time of complicated patterns from hours to minutes.

X-ray diffraction at temperatures above 2500K gives rise to a wide variety of problems. Not only is there the sample to be heated but also the attachment must be cooled properly, the sample's temperature to be measured and last but not least the sample evaporation to be considered, which sets a limit to the maximum temperature to be reached. There are still other factors limiting the specimen temperature, e.g. an emissivity of the specimen higher than that of the heating strip, a good electicai conductivity or a good thermal conductivity of the specimen material. All these influences were investigated in [1].

X-ray diffraction analyses were applied to various pure nickel substrates while exposing them to oxygen at temperatures up to 800 °C. Coefficients of thermal expansion (CTE) were calculated from lattice parameters for both the nickel and the growing surface oxides. Behaviors more complex than the case for single phase bulk solids were observed due, in part, to oxidationinduced strains. The CTE values for such dynamic composite systems are not the same as those for the bulk solids. Thus, for example, the CTE values were found to be dependent on substrate metal thickness. In addition, discontinuities in the CTE's of both nickel and NiO occurred at or near their respective second order phase change temperatures.

A low temperature attachment based on a miniature open-cycle Joule-Thomson refrigerator has been developed for x-ray diffractometry measurements over the temperature range from 65 - 400 K, By use of a special mounting plate, the device can be substituted for the heater assembly of a high temperature attachment and thereby utilize the available vacuum chamber and x-ray transparent beryllium window. The device is demonstrated by investigating the polymorphic phase transformations that occur in barium titanate.

The ODF calculation is, to a large extent, responsible for the increased interest in texture analysis. Accurate pole figures and ODF plots can be routinely obtained in the laboratory from x-ray units equipped with precision controlling devices. For studies of the plastic flow behavior of polycrystalline aggregates, it is important to present the texture results in a manner readily usable for these analyses. For samples having a simple concentrated texture, the presentation of the data in terms of conventional pole figures and ODF plots is usually adequate. Additional work however is frequently needed when the analysis is involved with a more complex texture. A method is described for constructing the quantitative inverse pole figure using the available ODF data. Attention is focused on the construction of inverse pole figures for FCC and BCC metals. Examples are given of the plastic flow analyses for copper and tantalum which were produced by different cold-forming processes to yield a multitude of texture elements. The modification and rearrangement of the computer program necessary to accomplish this task will be discussed.

The Rietveld method entails the calculation of a powder diffraction pattern from crystallographic, microstructural and equipment characteristics. These characteristics are related to the form of the pattern through a series of model functions. The difference between an observed and calculated pattern is then minimized by sequentially refining the physical parameters contained within the mode) functions to obtain an accurate and precise description of the specimen. A powder diffraction pattern from a specimen exhibiting cry stallo graphic texture, or preferred orientation, will display intensity values which differ systematically from those calculated for a specimen of random orientation. This systematic discrepancy can be addressed by incorporating into the Rietveld refinement a model function for sample texture. A successful model for texture will accurately assess the phase abundance and degree of texture from both oriented and randomized specimens. In this study we use the March-Dollase model function to characterize texture development in sintered alumina with respect to processing variables and sintering time.