Title: Ion Impact Chemistry in the System Ti-O, Author: Thomas E. Parker, Location: Thode / <p>This thesis considers the characterization of the phenomenon of the induced conductivity changes in TiO2 under the influence of krypton and oxygen ion bombardment and the damage layer associated with these changes. The investigation included the examination of the irradiated and irradiated specimens (variously-single crystals and polycrystals), using electron microscopy techniques to reveal surface structural alterations; electrical conductivity measurements to assess the response to irradiation; dissolution experiments of the bombarded region to estimate the thickness and radioactive inert gas marker release to monitor the annealing stages of the damage.</p> <p> The results included the observation of lower oxide formation under ion impact and its identification as Ti2O3 and suggest a technique for producing lower oxides of transition metal oxides that have a semiconductor to metal transition of technological interest.</p> / Thesis / Master of Engineering (ME)

Title: Deformation and Recovery of Iron Polycrystals, Author: Michael H. Schankula, Location: Thode / <p>The effect of grain size on the work hardening behavior of polycrystalline iron, copper, and 70/30 alpha brass has been studied using stress relaxation techniques. The stress relaxation technique has been used to monitor the variation of internal stress during work hardening as a function of grain size in these materials. It is shown that, for certain conditions dependent on the temperature and the nature of slip, the work hardening behavior of a metal polycrystal is grain size dependent and can be expressed in terms of a modified Hall- Fetch equation with a slope dependent on the degree of plastic strain. A simple dimensional argument is developed to show that under conditions of planar slip, where the slip distance is equivalent to the grain diameter, the grain size dependent work hardening is related to the accumulation of geometrically necessary dislocations required for the compatible deformation of the polycrystal.</p> <p>Recovery experiments have been used to study the thermal stability of the work hardened structure formed at different deformation temperatures in iron polycrystals.</p> / Thesis / Doctor of Philosophy (PhD)

Title: Low Amplitude Fatigue Hardening of Copper Single Crystals, Author: Douglas M. Shinozaki, Location: Thode / <p>The detailed dislocation microstructure was determined as a function of low amplitude fatigue in the hardening regime. Copper single crystals were cycled in uniaxial, symmetric push-pull at room temperature.</p> <p>The dislocation microstructures were observed by thin film electron microscopy for various extents of hardening. An attempt was made to correlate surface slip line observations to the dislocation . microstructures. On the basis of a similarity to the dislocation distributions observed in stage two of uni-directional work hardening, a model for fatigue hardening was proposed. Hirsch's stress relief theory of stage two work hardening was used to account for the observed dislocation distributions.</p> / Thesis / Master of Science (MS)

Title: The Growth of Intermetallic Phases on Iron Galvanized in an Aluminum-Bearing Zinc Bath at 450°C, Author: Miroslav Urednicek, Location: Thode / <p>This thesis is concerned with determination of the nature and growth characteristics of the intermediate phases formed on iron galvanized in Al-bearing Zn at 450°C, Long time equilibrium experiments have been carried out to explain the nature of intermetallic phases and their equilibria in the system Fe-Zn-AI at 450°C using electron probe microanalysis and metallographic techniques.</p> <p>The growth characteristics of intermediate phases formed on iron galvanized in AL-bearing Zn at 450°C have been investigated by metallography and low angle X-ray diffraction. It has been confirmed that the inhibition layer is composed of Zn-bearing Fe2Al5 and FeAl5. While the FeAl2 phase was erratically detected, we did not detect the presence of FeAl. X-ray diffraction data for FeAl2, so far missing from the ASTM X-Ray Data File, have been recorded. A correlation of our results and that of other workers with our newly investigated and proposed ternary isotherm at 450°C using an analysis via diffusion paths on the isotherm has produced a convincing rationalization of the inhibiting effect and the catastrophic interface instabilities which develop preferentially in stagnant baths after long times and with the higher bath Fe contents.</p> / Thesis / Master of Engineering (ME)

Title: Pitting Corrosion of Nickle, Author: Mohammed Zamin, Location: Thode / <p>The pitting corrosion of nickel has been investigated using potentio-static techniques, optical and scanning electron microscopy. The effect of grain size, cold work, annealing procedure and chlorine ion concentration has been investigated and analyzed from the point of view of the pitting susceptibility and passivity of nickel. It has been shown that electrochemical data must be supplemented by metallographic observations for a complete appreciation of the pitting phenomenon.</p> / Thesis / Master of Engineering (ME)

Title: Fracture in Low Carbon Steel, Author: Donald H. Timbres, Location: Thode / <p>A model for slip induced cleavage fracture has been proposed to account for the influence of both grain size and grain boundary carbide size on the fracture behaviour of low carbon steel.</p> <p>It was shown in low carbon irons that grain boundary carbides may fracture due to inhomogeneous yielding of the ferrite matrix and provide important sources of cleavage cracks which may propagate into the ferrite matrix.</p> <p>Reducing the size of the grain boundary carbide enhances the fracture resistance of the low carbon irons but continual removal has a deleterious effect.</p> <p>The onset of intergranular fracture has been rationalized in terms of the stress concentrations at the head of a dislocation pile-up.</p> / Thesis / Doctor of Philosophy (PhD)

Title: Uniform Ductility of High Carbon Steels, Author: Masaru Yamaguchi, Location: Thode / <p>The effect of microstructure on uniform ductility was analyzed by utilizing a fact that uniform ductility is equal to the work hardening coefficient in parabolic true stress-true strain equation. A Hall-Petch relation was found for the flow stress of lamellar and spheroidized high carbon steels. The uniform ductility was formulated as a function of reciprocal flow stress and found to fit the experimental data.</p. <p>An attempt to interpret the results obtained, based on the scanning and transmission electron microscopy observations, were given.</p> / Thesis / Master of Engineering (ME)

<p>This investigation is primarily concerned with the development of a suitable high-precision sectioning technique to be employed in studies of depth distributions of energetic ions in Mo and V. It consists of two main parts.</p> <p>In the first part, uniform anodic oxide films of controlled thicknesses have been grown on poiycrystalline V, Mo, and W (the latter, primarily for comparison with earlier works on W) in acetic acid-sodium tetraborate solutions containing small quantities of water. These anodic films which show bright characteristic interference colours when formed at >10 volts, are shown to be rapidly soluble in a dilute solution of KOH whereas the underlying metal is attacked at a rate of less than ~100Å per day. The thickness of the anodic films per volt has been established using ellipsometry and conventional weight-loss measurements.</p> <p>Kinetics of anodization have been studied at constant-current and constant-voltage. An analysis of these data shows the composition of the films on Mo and W to be close to Mo0₃ and W0₃ respectively while those on V were intermediate between V₂0₄ and V₂0₅. The density of the films on Mo and the differential field strength, E_d, for films on Mo and W have also been determined.</p> <p>In the second part, a theoretical background consisting of an outline of the theory of Lindhard, Scharff and Schiøtt, has been provided; in the absence of experimental data, this theory is generally used to estimate the depth distribution of ions in amorphous targets. Experimental range profiles have been determined for 5-30 keV Kr⁸⁵ in polycrystalline Mo using the technique developed in the first part and the results obtained show a large discrepancy when compared with Lindhard theory. The extent of disagreement with theory is similar to that obtained by previous workers with targets such as Al or W.</p> <p>Evidence is presented to show that this large discrepancy may be attributted to crystal-lattice effects (i.e. channelling). For example, it is shown that the discrpency is not due to the anodizing-stripping sequence being sensitive to bombardment. Also, it is demonstrated that the Mo used had a pronounced preferred orientation such that the open directiors <100>, <211>, and <111> were normal to the surface.</p> <p>An important part of future work will be to extend techniques such as those described here to the metal Be, for Be is the lightest target material that can be conveniently worked with.</p> / Master of Science (MS)

<p>[Missing page 58]</p> / Doctor of Philosophy (PhD)

In this thesis a study is made of the damage layer (as defined by its solubility in a HF-H2o2, or concentrated HF solution) produced by ion bombardment of Si. This thesis is concerned with not only the layer but also its usefulness in the study of radiation damage itself. The layer is examined with respect to the adverse effects it has upon the anodic oxidation and stripping technique, to the dose of incident ions required to produce it (ie the threshold dose), and to its relationship to the amorphous layer which has been observed with ion bombardment of Si. Annealing of the damage has been approached from two points of view. First the temperature dependence of the threshold dose is used to obtain information about the annealing of the damage that occurs between the formation of a discrete damage zone and the formation of a layer. Secondly using gas release of the radioactive Kr85 the annealing of the fully formed amorphous damage layer is followed. The solubility of the damage layer in a HF-H2o2 solution is shown to be a very useful tool in the study of radiation damage. Firstly it provides a convenient means of obtaining the mean range of the damage distribution as a function of incident ion energy. Secondly it is used to obtain the threshold dose for the formation of the damage layer, and thirdly it is used in the gas release experiments to give more detailed information about the Kr85 motion. / Thesis / Master of Science (MS)