The use of CaF2 (Dy) thermoluminescent dosimeters to diagnose the X-radiation from 1.06 μ laser-produced plasmas is described. The TLD's have been used in various cassettes to measure total X-ray yield and the X-ray continuum out to ∼100 kev. Described are experiments pertaining to maintenance and recovery of TLD soft X-ray response, their linearity, insensitivity to 1.06 μ laser light, and energy calibration. Also, described are the TLD attenuation experiments in the “soft” and “hard” components of the laser plasma X-ray spectrum.

One of the areas of X-ray powder diffraction receiving considerable attention in recent years is quantitative analysis. This analysis depends on an accurate measurement of integrated diffraction line intensities. In order to study the accuracy of these measurements we have calculated integrated intensities from single crystal data for single substance powders and compared them to experimental data obtained in our laboratory.

A requirement exists in the aeronautical industry for measuring temperature non-invasively in critical components, such as the turbine disc in an operating engine. Neutron diffraction, unique among nuclear techniques, offers the possibility of measuring both temperature and strain within an operating engine by virtue of the high penetration of neutrons through industrial materials. Static diffraction experiments on Waspaloy and Ti6A14V showed, by comparison with thermocouples, that both the diffraction peak position and the peak intensity can measure the tempeiaturc to within ±6 K aL 800 K. Measurements on a rotating Waspaloy disc, heated from its rim, showed that temperature gradients could be determined accurately by lattice parameter measurements. The large grain size in Waspaloy prevented accurate peak intensity measurements in this dynamic test. Finally, the structures within a small Pratt & Whitney engine in its equatorial plane were mapped by mounting the engine on an X-Y translator on the diffractometer and moving it through a grid of positions. Possible future directions in the field will be discussed.

The sources of raw materials used in the manufacture of Portland cement include pure to argillaceous limestones, shale and clay, plus minor quantities of sand, iron ore, fly ash, coal ash and suitable industrial wastes. To ensure a high quality product, rapid - precise - reproducible and practical analytical techniques are required. Quantitative XRF analysis techniques meet those demands.

For this comparative technique, the instrument used is a wavelength dispersive sequential spectrometer. The advantages and the drawbacks of the technique are discussed, along with the procedure of the specimen fused bead preparation. The importance of calibration standards and unknown samples being prepared in an identical manner, and being presented to the instrument under similar conditions, is stressed. International and synthetic standards, concentration ranges for the five major elements, mathematically generated coefficients to correct absorption and enhancement effects, and a summary of the standard error of estimates are examined and discussed.

The accuracy of the method is verified by the analysis of known standard reference materials such as obsidian rock, coal fly ash, argillaceous limestone and blastfurnace slag. The values are compared with the known certified values.

One of the most difficult tasks in applied and residual stress measurement of polycrystalline materials using x-ray diffraction is dealing with preferred orientation and large grain size.

A common solution to large grain size problems has been to choose a larger aperture, but in certain cases this is undesirable and/or impossible. When preferred orientation has been identified as the problem, the common approach has been to choose another diffraction plane or oscillate the x-ray diffraction head during data collection. Remedies such as these can distort the peak breadth and are often not sufficient to totally negate the grain size and preferred orientation effects.

A technique described as the “step scan with virtual window” has been developed jointly at MTL (formerly Canmet) and Proto Mfg. Ltd. to deal specifically with the aforementioned effects of grain size and preferred orientation.

This paper highlights some of the problems that arise in stress analysis of materials exhibiting preferred orientation and large grain size. Subsequently a comparison of the results obtained using standard diffraction technique, oscillation and the “step scan with virtual window” is made.

Trace elements in oil may be determined by adsorption of the oil sample onto maguesium oxide followed by thermal degradation of the organic material. The resulting powder is easily pressed into a pellet suitable for X-ray spectrometric analysis. The lower limit of detection depends upon the trace impurities in the MgO and is a few parts per million for most elements determined.

X-ray fractography is a new method utilizing the X-ray diffraction technique to observe the fracture surface for the analysis of the micromechanisms and mechanics of fracture. The X-ray residual stress has been confirmed to be a particularly useful parameter when studying the fracture surfaces of high strength steels. The method has been applied to the fracture surface of fracture toughness and fatigue specimens.

The salts of hydrazine or methyl derivatives of hydrazine were prepared by neutralization of the base with inorganic acids, for instance, HBF4, HClO4, H SO4, and HCl. Upon recrystallization of the product from a suitable solvent, X-ray diffraction patterns were obtained. Hydrazine tetrafluoborate H2N-NH2·HBF4 was found to crystallize in the monoclinic system. Cell dimensions and possible space groups were determined. The corresponding perchlorate salt crystallizes in two forms, one of which is isomorphous with hydrazine tetrafluoborate. The second form seems to be stabilized by small amounts of water.

The tetrafluoborate salt was prepared from the 1,1-dimethyl hydrazine. It was found to crystallize in the tetragonal system with a primitive unit cell. The perchlorate salt of this base is isomorphous with the fluoborate but with a slightly larger unit cell. Both materials undergo plastic-like deformation. The general appearance and mechanical properties are similar to those of a hydrocarbon wax. The 1,1-dimethyl hydrazine sulfate and the 1,1-dimethyl hydrazine hydrochloride have a lower symmetry than the HBF4 salt and do not show the wax-like properties of the latter. Based on the study of these chemically related compounds an explanation is offered for the properties of 1,1-dimethyl hydrazine tetrafluoborate in terms of crystalline structure.

Characteristic soft x-ray emission lines created as a result of low energy (10-100keV) positive ion excitation of a target material has been applied to the study of thin films of oxygen that form naturally on metal surfaces. The specific metals investigated were aluminum and nickel aa well as a number of their corresponding alloys.

Low energy positive ions are well suited as projectiles for the study of thin films in that they have low penetrating powers, yet produce high x-ray yields for K-, L-, and M-shell elemental x-ray lines. Perhaps the most important feature is the fact that no background bremsstrahlung continuum x-radiation is generated in the slowing processes of the ions. Exploiting the advantages of these facts, a special high sensitivity detection technique has been developed for the soft x-ray analysis of the constituents that make up a particular thin surface film.

The physical basis for thickness and atomic density measurements of thin surface films by positive ion excitation are discussed. Calibration data are presented for thin films of known thickness and composition establishing the sensitivity of the method for the measurement of the elemental atomic densities of thin films down to a few monolayers or approximately 10 Å in thickness. Finally, the results of the analysis of oxide surface films of aluminum, nickel and some of their alloys are presented and discussed.

The objective of this continuing program is to gain an understanding of the mechanisms and principles governing the formation of oxide surface films on metals with the basic goal of producing new alloying techniques for metal passification in a saline environment.

For phase analysis of small amounts of material in an x-ray powder diffractometer the sample is often spread on a sample mounting plate or support plate. Different types of plates on which thin samples can be mounted are:

• - silver membrane filters

• - metal or other polycrystalline plates

• - polymer membrane filters, for example PVC, polycarbonate, cellulose nitrate

• - glass slides

• - single crystals; cut so that no diffraction lines occur.

Filters are often used to collect environmental dust; these samples can be analysed “as received,” Glass slides are inexpensive, flat, and readily available. Polycrystalline filters and plates have the disadvantage of possible line overlap with lines of the sample material (refer to figure 1), Glass plates or polymer filters have the high and curved background due to amorphous scatter as shown in figure 2.

The operation of a new polycrystalline phase identification method using the IBM Series/1 minicomputer is described. Data of the unknown can be entered by automatic transfer of previous runs, stored data sets and manually. Full screen menu selections are provided to facilitate operations and correct entries. Typical S/M time for a multi-phase inorganic mixture containing 43 reflections using a 0.3° window averaged 11 sec per 100 standards and with simple chemical prescreening less than 4 sec including program initialization and calculations of comprehensive figures of merit. Interactive options provide graphics terminal comparison of the unknown pattern with selected standards which appear as diffractometer patterns, subtraction of identified standards from the unknown and others. Utility programs permit storing data sets for later analysis, user created files and a program to display any file standard as a diffractometer pattern.

In any petroleum product, a high sulphur content is considered undesirable. Sulphur in diesel fuels is claimed to aggravate problems of wear and deposit. With residual oils used in some metallurgical operations, the sulphur combustion products can have an adverse effect on the metal. In combustion equipment, the oxides of sulphur together with water vapour can lead to undesirable acid condensatlon on cool metal surfaces.

The more general problem is air pollution. Local and national legislation present the oil industry with a continuing demand for fuels of lower and lower sulphur content. Best use must therefore be made of crude oils of inherently low sulphur content. Desulphurising processes are comnonly used for distillates and are available for residual products. Such processes however tend to add significantly to produetion costs.

Zn-Ni-alloy electroplated steels are used for the parts of automob iles because of their high corrosion resistance. in the x-ray stress measurement of this material, some unique experimental results were observed: (i) The sin2Φ diagrams were severely curved, and (ii) the influence of the wave length of x-ray radiations upon the shape of the d-sin2Φ diagram was very slight. As no strong texture or the gradients of composition were observed in this material, the above experimental results suggested the existence of steep stress gradients in the direction of depth, and a theoretical problem on the difference in the effective penetration depth of x-rays and the weighted mean of the lattice strain between thin films and ordinary thick materials.

Uniformity of particle size is most critical iti both X-ray spectrographic and diffraction samples. This is especially true when there are both hard and soft materials in the sample. The soft material reduces to a smaller particle size and therefore presents a great density and area to the X-ray beam. Accurate quantitative determinations are most difficult under these clrcum s tances. This paper decribes a means of grinding to a more uniform particle size and presents graphic data on the effects of particle-size variation.

A technique is described for the study of the early stages of precipitation hardening in single-crystalline and poly crystalline copperberyllium alloys. Since no trace of the equilibrium precipitate responsible for hardening can be detected by ordinary X-ray or metallographic techniques prior to the onset of overaging, the described method is based on the changes produced in the matrix as the result of the formation of aggregates along preferred lattice planes. Such formations produce accommodation strains in the matrix lattice which, can be detected as a change in the intensity and angular range of matrix reflection.

An interpretation of the age hardening sequence in a copper - beryllium, alloy after isothermal annealing is presented in terms of fundamental transformations.

The characteristic 17.441 keV Mo-Kα tube line yields an exceedingly strong reflection at a Bragg angle of 6.0710 on Highly Oriented Pyrolytic Graphite (IIOPG). Using doubly bent toroidally shaped crystals we were able to concentrate the characteristic radiation from a Mo anode fine focus tube onto a small focal spot area of about 1 mm. FWHM diameter, as was observed by an X-Ray sensitive CCD. The radiation of the Mo anode fine focus tube is emitted at a take-off angle of 60 into a total solid angle with an aperture of 120. About 90 percent of this primary radiation solid angle can be used for the desired Bragg reflection on the designed toroidal crystal surface. This feature ensures the high beam intensity needed for special excitation problems.

Although no revolutionary advance has been achieved in the last two decades, X-ray diffraction is not to be considered as a quiescent field of physics. Actually many improvements, in theory as well as in experiment, slight by themselves but very numerous, have considerably increased the efficiency of techniques such as the determination of crystal structures, the analysis of crystalline phases, and the applications of X-rays to various problems of the physics of solids. Only the two last points will be dealt with here:

1. 1. Crystalline phase analysis. The development of a satisfactory atlas of powder patterns has been too slow, and the data are not yet complete and precise enough to permit a rational utilization of the modern diffractometers. A very interesting new approach is the systematic indexing of the powder patterns which would be possible with computers. In the near future, anyone should be able to analyze a powder at any temperature as an easy routine experiment.

2. 2. The study of lattice defects. X-ray techniques are now in competition with electron microscopy, the development of which has been very successful in recent years. Now we have a better understanding of the possibilities of both techniques. X-rays give better results to determine the statistics of an extended disorder even if it is slight (e.g., degrees of order in a solid solution), and the microscope is more powerful for the detection of large but rare defects (e.g., dislocations).

At the present time there is considerable interest in the use of adhesive bonded joints for structural applications. The design of such joints is based mostly on finite element calculations and failure tests rather than on strain or stress measurements. To our knowledge no measurements have been made of stresses at or near the adhesive/adherend interface (where many bond failures occur) because of difficulties with accessibility. The purpose of this work was therefore to try to make such measurements using X-ray diffraction.

The approach taken was to gain access to the bond by making one of the adherends in a single lap joint to be relatively transparent to X-rays and the cither relatively opaque. Incident X-rays then penetrated the first adherend and the adhesive and were diffracted from gains in the second adherend adjacent to the adhesive/adherend interface. Stresses resulting from curing of the adhesive were determined first, after which a load was applied and the stresses redetermined.

The statistical fluctuations of photon counts arediscussedas a factor limiting the precision of the analytical result. Assuming a Poisson distribution, the theoretical standard deviation of the result can be calculated. While this prediction does not consider causes of variation other than the count statistics, it is useful in developing methods and checking instrument reliability. Practical examples using experimental results are given.

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.