Search/match of XRD patterns of pure phases can prove useful for verifying the internal consistency of search algorithms. An additional benefit is to check whether there are other materials giving similar powder patterns. If displacements and/or distortions are applied to the input patterns, such trials become a convenient way to estimate the program's tolerance to 2θ errors.

This study has been performed on a set of 70 diffraction patterns from pure phases prepared by the International Centre for Diffraction Data (ICDD) for another purpose. Three search runs were performed on the background corrected full patterns, each time with the default parameters, and on the complete database (59,990 potential candidates): the first run without applying an offset, secondly with +0.20° 2θ offset and thirdly with -0.20°.

The results show that a +/- 0.20° error is still acceptable for non-ambiguous identification of pure phases.

A dedicated on-stream X-ray diffraction (XRD) system for the analysis of rock phosphate-bearing slurries was configured to the requirements of industry for process control. The slurry-handling system includes a multiplexer, header tank, de-aerator, sample splitters and two windowless sample presenters. The x-ray system is comprises a line-focus molybdenum anode X-ray tube, two pyrolytic graphite primary-beam monochromators, two vertical fixed-geometry goniometers, and a simultaneous four scintillation-detector system. The X-ray beam is transmitted through the slurry curtains so that the forward diffracted X-ray intensities of apatite (francolite) and quartz are measured simultaneously. Data obtained by the on-stream XRD analyses of apatite and quartz in rock phosphate from the Florida area in the USA are presented. Lower limits of detection in the order of 0.1 per cent can be achieved for both the apatite and quartz in slurries containing 30 per cent solids. The solids content is a variable that must be known if feeds, tailings, and concentrates are to be measured using a universal algorithm. It can be calculated from the total mineral content of the slurry or from density measurements.

Reference intensity ratios (RIRs) with zincite (ZnO) as the internal standard have been measured and calculated for key phases in coal combustion solid residuals. Detailed comparisons of measured and calculated corundum RIRs (converted from zincite RIRs), and literature I/Ic values led to the conclusion that for best results, laboratory measured values must be used. Using measured zincite RIRs and standard mixtures of important crystalline phases, a protocol for routine semi-quantitative analysis has been developed. The need to grind under ethanol to minimize decomposition of hydrated phases was demonstrated. An unusual procedure employing mixed peak and integrated intensities in the RIR of one key phase, ettringite (Ca6Al2(SO4)3(OH)12-26H2O), has been adopted for this protocol.

Scattering technigues have been employed since the beginnings of polymer science to provide information on the spatial arrangements of macromolecules. The first measurements were made in the 1920s and were concerned primarily with the determination of crystal structures via the Bragg law

nλ = 2dsinθ.

The physical properties of polymer blends consisting of one or more crystallizable components are affected by the microstructure of these materials. In particular, the degree of crystallinity can be influenced by processing parameters, and the crystallinity, as well as the phase distribution, may vary as a function of depth through an injection molded part. Conventional x-ray diffraction techniques can provide information regarding both phase composition and degree of crystallinity, but, because of the relative transparency of these materials to wavelengths generally available in the laboratory, these techniques provide information representative of only the bulk. By employing parallel beam optics at varying grazing incidence angles, the x-ray sampling depth can be varied without loss of resolution, This technique can be used to vary the effective analysis depth from the top several hundred angstroms for low grazing incidence to centimeters for transmission diffraction patterns, Grazing incidence techniques have found initial application in the characterization of thin metallic and ceramic films. This paper demonstrates the feasibility of using parallel beam optics to depth profile low atomic number materials. The specific application of this technique to the characterization of injection molded polymers, including a blend of bisphenol-A polycarbonate (PC) and polybutylene terephthalate (PBT), will be presented.

The effect of dimethyl-5-sodiosulfoisophthalate, SIP, on poly(ethylene terephthalate), PET, crystallization has been studied using in situ high-temperature x-ray diffraction, HTXRD. At low levels of SIP modification, PET-like crystallinity was observed. At high SIP levels, clustering of polyester ionomers was observed and crystallization was significantly suppressed. The HTXRD data along with differential scanning calorimetry, DSC, and small angle x-ray scattering, SAXS, indicate that the change from bulk crystallization to bulk ionomer formation occurred when 8-12 mol% of the diester linkages contained SIP.

The Fuji Imaging Plate (IP) is a 2-Dimensional X-ray detector on which a latent X-ray image is stored as a distribution of color centers in a photo-stimulable phosphor(BaFBr:Eu) screen. It has excellent characteristics such as a wide dynamic range of five or more digits and an order of magnitude higher sensitivity than X-ray film. Thus it has been actively used in the field of X-ray single crystal structure analysis.

For polymer studies, 2-D information is useful to analyse a sample's orientation or periodic structure, and some system such as 2-D position sensitive detector (PSD) are widely used. But in spite of the superior performance of the IP which will give significant advantages in various measurements, few applications have been reported in this field, because most conventional IP based systems are specialized for the single crystal structure analysis,

Therefore we developed the R-AXIS II D (Rigaku Automated X-ray Imaging System II D), an IP reader for general X-ray diffractometry which has a removable IP in order for exposure with external X-ray optics, and software which converts 2-D data to conventional 2theta-intensity or beta-intensity data for analysis of crystallinity or orientation. In this paper, we report the performance of R-AXIS II D and its applications to polymer studies and thin film analyses.

For the generation of high temperatures in X-ray and neutron diffraction experiments various techniques such as resistance heating, radiation heating, induction heating and gas flame heating have been applied (Aldebert, 1984). Mirror heaters usually employ some kind of focussing geometry to concentrate the radiation emanating from the heating element onto the sample: Two large parabolic mirrors focussing heat radiation from a carbon arc were used by Stecura (1968) to reach sample temperatures up to 1700°C. Hubert et al. (1974) used radiation from a short arc xenon lamp focussed by two parabolical mirrors to reach sample temperatures of 3200°C.

A prototype of a new high temperature chamber has been developed at our institute. Like most of such chambers it has an evacuated housing which is watercooled, and in its center a tungsten heating strip is mounted on watercooled clamps (fig.1). A special way of clamping compensates for thermal expansion automatically and thus keeps the specimen in an aligned position. The specimen is mounted directly onto the heating strip's surface. Specimens are prepared using fine powders mixed with distilled water and acetone to give a thin slurry. This mixture is put onto the heating strip and carefully dried with a heatgun. This way of preparing a specimen makes it cling to the heating strip quite well even at temperatures above 3000K and therefore provides good thermal contact.

A high temperature in situ X-Tay diffraction (HTXRD) instrument was devised for residual stress (RS) and X-ray elastic constant (XECs) investigations. The aim was to gain a better understanding of the stresses developed during high temperature oxidation, which is essential for the lifetime improvement of refractory alloys. The investigators use sin2ψ method to survey the stress evolution during oxidation in both the scale and the substrate, and differential method to determine the XECs that relate the measured/measurable deformation to the stress state of the materials studied. The stresses on the Ni/NiO system are measured in situ. The XECs are determined on XC75 steel samples. This paper presents the theories of stresses and XECs determined by HTXRD and briefly discusses the experimental results.

Type 310S stainless steel was exposed in air at 900°C and simultaneously examined periodically by X-ray diffraction in an attempt to determine the structural evolution of the compounds formed on its surface. The adherent oxide product was found to be a two-layered scale composed of an inner sesquioxide and an outer spinel layer. Both of these compounds exhibited systematic changes in their unit cell sizes as a function of increasing exposure time at constant temperature. The spinel showed an increase in its lattice parameter while the sesquioxide and stainless steel substrate both had decreases in their parameters proportional to the square root of exposure time. In each of the three phases, the rate of change was constant up to approximately four hours after which the parameters approached a limiting value. Evidence also exists for the presence of at least localized stresses in the scales.

Commercial resistance heating and thermocouple materials specified for use in air at temperatures up to 1200°C were examined as possible alternatives to Pt-Rh for use as heater strips in high temperature x-ray diffractometer furnaces. Tests in air at 1150°C, showed that Chromel oxidized excessively, Nichrome oxidized moderately, while Kanthal was very slightly oxidized. Nichrome and Kanthal strips were sufficiently ductile to fabricate into strip heaters. The thickness of the Kanthal strip had to be reduced to 0.020 mm to match its resistance to the power and temperature control software of the high temperature diffractometer. Heater strips made from Nichrome proved effective, in terms of resistance to grain growth and surface degradation by adhesive liquid phases, at temperatures up to 1000°C, while Kanthal was effective up to 1150°C. The relatively low costs of these materials also make them viable as disposable heaters for use with chemically reactive or strongly adherent materials.

Humidity sensitive mineral phases change their structure when humidity varies resulting in X-ray pattern changes in intensity, position, and shape of lines. These structural changes in hydrous minerals are induced by dehydration and rehydration, which can lead to phase transformations or to steady depletion which may result in a total structure collapse. By means of X-ray diffraction with a special attachment, such reactions can be followed. The controlled relative humidity is provided in situ, in a closed cell, by a flow of moistened helium gas which is flushed through the cell during the XRD analysis. Humidity diffractometry allows studies of reaction rates of dehydration-rehydration reactions and their reversibilities, as well as effects of additives and impurities on these reactions. Potential applications in basic research and in industry are demonstrated using montmorilionite, ettringites, sodium carbonates and calcium sulfates.

Deformation in polycrystalline materials is highly inhomogeneous on a micro scale. This inhomogeneity arises from the anisotropy of the constituent grains, coupled with local configurational parameters such as texture, gram size or proximity to a free surface. In a recent paper, we had outlined a new method that extended the traditional x-ray stress analysis to yield quantitative measures of such inhomogeneous deformation. In this paper, this method is used to study the partitioning of inhomogeneous deformation between the phases of 60-40 brass tensile specimens subjected to applied loads.

There has been a great interest in metal matrix composites during the last 10-15 years. The reason is their potential to achieve a high strength and good dimensional stability in a large temperature range and to obtain a good stiffness. The interest has particularly been focused on light metals reinforced with a continuous or discontinuous ceramic phase. The reinforcement and the matrix have very different properties such as thermal expansion and elastic modulus, which of course is the point in using this type of reinforcement. These differences between matrix and reinforcement gives rise to residual stresses after temperature changes or after plastic deformation.

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.

Metal matrix composites develop residual strains after consolidation due to the thermal expansion mismatch between the reinforcement fiber and the matrix. X-ray and neutron diffraction measured values for the longitudinal residual stress in the matrix of three titanium MMCs are reported. For thick composites (> 6 plies) the surface stress measured by x-ray diffraction matches that determined by neutron diffraction and therefore represents the stress in the bulk region consisting of the fibers and matrix. For thin sheet composites, the surface values are lower than in the interior and increase as the outer rows of fibers are approached. While a rationale for this behavior has yet to be developed, accounting for composite thickness is important when using x-ray measured values to validate analytic and finite element calculations of the residual stress state.

We studied particle-reinforced 6061-aluminum-alloy composites with particle volume fractions ranging from 0 to 0.25. The mullite particles are approximately spherical and contain embedded α-alumina phase. We obtained lattice parameters of all three phases in the composites and starting materials by using Rietveld refinement of x-ray diffraction patterns. In all three phases stresses are tensile and approximately of the same magnitude, contradicting a requirement for mechanical equilibrium. Stresses increase with both increasing particle size and volume fraction. Measurements of extracted-from-composites particles showed no evidence of a possible chemical reaction at the matrix-particle interface. The matrix is [111] and [100] textured, but measurements of elastic constants reveal only small anisotropy. Thus, explanation of the mechanical-equilibrium violation remains uncertain.

Neutron powder diffraction techniques have been used to characterize the pseudo-macro (PM) residual stresses in ZrO2(CeO2)/Al2O3 ceramic composites as a function of ZrO2(CeO2) volume fraction and fabrication procedures. The diffraction data were analyzed using the Rietveld structure refinement technique. From the refinement, we found that the CeO2 stabilized tetragonal ZrO2 particles were in tension and the Al2O3 matrix was in compression. Different sintering time had little impact on the PM stresses. On the other hand, the magnitude of the PM stresses in both ZrO2 and Al2O3 decreased linearly with the increase of their volume fractions.

The authors tried a new measuring method for stresses in small areas of ceramics. This method is characterized by the following.

1. 1) Applicable to small areas.

2. 2) High sensitivity.

3. 3) Stress calculations by measuring the average Debye ring radius in view of spotty diffraction rings.

4. 4) The use of an imaging processor for (3).

5. 5) The use of an imaging plate (IP) for reducing the exposure time.

We worked out a computer simulation about errors of the values measured by our method. The result showed a good approximation. With a test piece applied with a certain load, the difference between stresses measured by our method and those by a strain gauge was about 12 percent. We applied this method to the measurement of residual stresses which took place near the silicon nitride (Si3N4)/304 stainless steel brazing point interface. In the case of using an X-ray beam of 100 μm diameter, the exposure time was 90min with a high sensitive X-ray film and 3min with the imaging plate. In the case of an X-ray beam of 40 μm diameter, it was 120 to 190 min with the imaging plate.