Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 56-57). Also available on the World Wide Web.

Copper whiskers were grown by the hydrogen reduction of the halide vapours. The substrate and the whiskers were examined for growth morphologies. Whiskers of (100), (110) and (111) orientations in the diameter range 30-400μ were tested in tension. Differences in the work hardening characteristics of (111) and (100) whiskers were discussed in terms of the different kinds of jogs formed in the two orientations. Analysis of the diameter dependence of the yield stress resulted in a 1/d relation based on the assumption of surface nucleation of dislocations. Temperature and strain rate change experiments were made on (110) whiskers. Activation distance and activation energies were used to determine a rate controlling mechanism. At low temperatures, cross slip and intersection processes were indistinguishable, while at higher temperatures, cross slip is rate controlling. From the calculated activation distance and for a given rate controlling dislocation mechanism, stacking fault energies were estimated for copper and other FCC metals. A twinning model was proposed based on the idea of failure by recombination of a Lomer-Cottrell barrier. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

At the onset of this study, the work presented in Chapter 3 of this thesis was the primary focus. The work was motivated by JF Prins where he observed the formation of diamond layers on copper followed by C+ implantation into copper. This initial result suggested that it may be possible to generate single crystal diamond layers on single crystal copper. Subsequent efforts to reproduce this result failed. A unique end station was developed where a number of parameters could be altered during the implantation process. A series of carbon ion implantations were carried out on copper and copper-nickel (FCC) single crystals in this end station. The layers were characterised using initially Auger Electron Spectroscopy (AES), Low Energy Electron Diffraction (LEED) and later Raman Spectroscopy. During the early period of this study, the surface science equipment at the then Wits-Schonland Research Institute for Nuclear Sciences, was constantly giving problems. The time constraints on waiting for funds to be made available to repair the equipment, urged me to pursue alternative research endeavours and the results of this research is presented in chapter 4 and 5. The initial work will be investigated further in the future. Details of the end station are presented and the initial results of carbon layers generated in this end station are presented. In chapter 4, a study of C+ implantation into a type IIa (FCC single crystal) diamond using the cold implantation rapid annealing (CIRA) technique is reported. The Raman spectrum was recorded as a function of annealing temperature and C+ ion dose. De- fect peaks at 1450, 1498 and 1638 cm−1 appear in the Raman spectra, which have been previously considered to be unique to MeV implantation. The maximum energy of implantation used in this study was 170 keV. The peaks were monitored as a function of annealing temperature and ion dose. The annealing behaviour of the peaks were similar to those observed in the MeV implantation experiments. It is thus concluded that the defects that give rise to these peaks are related to the point-defect interac- tions that occur within the implantation regime and not to the implantation energy. 1 Understanding the nature of the defects that arise during the implantation annealing process, allows one to manipulate the implantation-annealing cycle, so as to generate defect structures that are useful in the fabrication of an active device in a diamond substrate. This is shown in chapter 5. A p-type (type IIb, FCC crystal) diamond was implanted with either carbon or phos- phorus ions using the cold implantation rapid annealing (CIRA) process. In each case, the energies and doses were chosen such that upon annealing, the implanted layer would act as an n-type electrode. The electroluminescence (EL) emitted from these carbon and phosphorus junctions, when biased in the forward direction, was compared as functions of annealing and diode temperatures. Typical luminescence bands such as those observed in cathodoluminescence (CL), in particular blue band A (2.90 eV) and green band (2.40 eV) were observed. Two bands centred around 2.06 and 4.0 eV were also observed for both the carbon and phosphorus junctions, while a band at 4.45 eV appeared only in the phosphorus implanted junction. This was the first time that the 4.45 eV band was observed in an electroluminescent junction.

No description available.

No description available.

No description available.

No description available.

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

In order to test the apparently conflicting predictions of some current theories of strain hardening, slip line length measurements were made on a series of oriented copper single crystals, identically prestrained at 673°K, polished and incrementally strained at temperatures between 573°K and 4.2°K; slip lines formed during low temperature increments were found to be longer than those formed during strain increments at higher temperature (Garner and Alden, 1974). The result is shown to be in conflict with any theory of strain hardening in which slip lines are blocked by specific obstacle configurations, such as Lomer-Cottrell barriers, ribbons of converted pile-ups or dislocation cell walls. In contrast, the result is shown to be consistent with theories of strain hardening in which slip lines are blocked by statistical interaction between expanding glide loops and forest dislocations, on the condition that, within the framework of such a theory, the glide loops are able to expand athermally over a newly available free area of slip plane, after a thermally activated process. Two possible thermally activated processes are discussed. A unified view of slip lines properties is presented which is shown to provide a self-consistent explanation of the temperature variation of slip line length, slip band formation, the existence of multipole carpets and the variation of flow stress with temperature. The statistical aspects of this interpretation were investigated further by obtaining 77°K microstrain curves from a series of oriented copper single crystals, prestrained at temperatures between 1000°K and 77°K, to produce dislocation microstructures with differing degrees of regularity, yet with approximately the same overall density. The forest dislocation microstructures of an identically prepared series of crystals were examined using a dislocation etch on the primary slip plane. A statistical sampling technique was devised, which was used to measure local dislocation densities. In addition, new parameter is introduced, namely the ratio of the sampled standard deviation, to mean local dislocation density, which quantifies the degree of regularity of a dislocation micro-structure. All microstructures were found to have a smaller degree of regularity than a random distribution. For crystals prestrained at temperatures above 293°K, at any given fraction of the 77°K yield stress, the amount of microstrain was found to increase as the microstructures became less regular. Crystals prestrained at and below 293°K exhibited the Haasen-Kelly effect, which was attributed to restricted source operation. However, once sources begin to operate, the amount of microstrain anticipated from the degree of regularity was indeed detected. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate