Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. Includes bibliographical references.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 139-148).

<p> The macroscopic mechanical behaviour of alloys is intimately related to their structure at the atomic level. The influence of small (<0.1μ) ordered coherent particles (𝛄') on the mechanical properties of Ni-Al alloys has been studied. The maximum strength of polycrystals occurs at 0.45 volume fraction 𝛄' and grain boundary embrittlement occurs at higher volume fractions. It was shown that long range order in the particles affects strength by increasing the anti-phase boundary energy. In monocrystals the deformation behaviour is strongly influenced by the amount of particles present. </p> <p> By growing very large particles of 𝛄' (~1.0μ) dislocation-particle interactions have been studied. Stacking faults have been observed in the particles whose bounding dislocation Burgers vectors were determined. By suitable heat treatment still larger 𝛄' particles (~10µ) were formed which had incoherent interfaces. The dislocation networks at the interfaces were analysed. </p> / Thesis / Doctor of Philosophy (PhD)

No description available.

published_or_final_version / abstract / Mechanical Engineering / Master / Master of Philosophy

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 86-89). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 86-89). Also available on the Internet.

Thesis (Ph. D.)--Lehigh University, 2003. / Includes vita. Includes bibliographical references (leaves 198-205).

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: Patrick S. Nicholson. Includes bibliographical references (leaves 162-181). Also available online.

The lack of ductility of the B2 NiAl alloy stands in the way of promising applications. In an effort to understand the dislocation behavior, computer simulation of the planar faults involved in the core spreadings of <100> and <111> dislocations was carried out. Seven γ-surfaces were computed for different crystallographic planes ({110}, {112}, {123}, {210}, {100}, {111} and {122}). Stable APB's are observed in the {110} and {112} planes but they are deviated from the exact 1/2a<111> position. No other stable planar fault was observed. The dislocation core spreadings are explained by the energy balance among the directions of lowest restoring forces observed in the γ-surfaces. The complete <111> screw dislocation was stable in the simulation. According to the stable APB's, two dissociation reactions of the <111> screw dislocation in the {110} and {112} planes are proposed. The simulation of metastable superpartials shows that the dissociation in the {112} planes is very close to a stable dissociation. / Master of Science