Thesis (Ph. D.)--University of Washington, 1988. / Vita. Bibliography: leaves [94]-101.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xxxi, 307 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Hamish L. Fraser, Dept. of Materials Science and Engineering. Includes bibliographical references (p. 302-316).

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 219-230).

Thesis (M. S.)--Ohio State University, 2008. / Title from first page of PDF file. Non-Latin script record Includes bibliographical references (p. 86-90).

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xxiii, 229 p.; also includes graphics (some col.) Includes bibliographical references (p. 224-229). Available online via OhioLINK's ETD Center

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xxii, 220 p. : ill. (some col.). Advisor: Hamish L. Fraser, Materials Science and Engineering. Includes bibliographical references (p. 217-220).

The decreasing solid solubility limit at the titanium-rich end of the titanium-copper constitutional diagram suggests the possibility that titanium-rich alloys may be age-hardenable. However, results obtained by previous investigators, using lump samples, show that after quenching from 790°C the age-hardening of an alloy containing 1,7 percent copper is very light while a 0.8 percent copper alloy decreases in hardness, during heat treatment at 400°C. It was believed possible that powder samples of alloys might show different results from the lump samples used by previous investigators. Consequently, a 1.90 percent copper alloy was made by the technique of levitation melting, checked for homogeneity, and filings of 48-65 Tyler screen size were cut from it for aging experiments. Hardness readings do show a hardness peak at aging temperatures of 400°C, 450°C, and 500°C and thus indicate that the titanium-copper alloy is susceptible to age-hardening treatments. Interest in the Mn₆₀A1xZn₂₀_ₓC₂₀ and Mn₆₀GaₓZn₂₀-ₓC₂₀ systems results from pregious studies of Mn-A1-C, Mn-Zn-C, and Mn-Ga-C systems; in particular the alloys near compositions Mn₆₀A1₂₀C₂₀, Mn₆₀Zn₂₀C₂₀ and Mn₆₀Ga₂₀C₂₀. The saturation magnetization (σ) versus temperature (T) curve for alloys near the compositions Mn₆₀A1₂₀C₂₀ and Mn₆₀Ga₂₀C₂₀ shows normal ferromagnetic behaviour from 0°K to the Curie points of the alloys. Alloys near the composition Mn₆₀Zn₂₀C₂₀, on the other hand, have abnormal behaviour as they experience a maximum in the σ-T curve in the neighbourhood of -40°C. Reasons for investigating the Mn₆₀A1Zn₂₀-xC₂₀ andMN₆₀GaₓZn₂₀-ₓC₂₀ systems were: 1. to provide further data regarding the presence of abnormal behaviour in Mn₆₀Zn₂₀C₂₀ and of normal behaviour in Mn₆₀A1₂₀C₂₀ and Mn₆₀Ga₂₀C₂₀. (i.e. alloys near these compositions). 2. to suggest how the valency of the cube-corner atom affects the normal ferromagnetic moment of these alloys. However, investigation of these systems has lead to even more complicated phenomena, and the above two items remain, to a large extent, unsolved. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

Manufacturing titanium alloys with simultaneous improvement in strength and ductility poses a challenge which exceeds that of purely cubic metals. Various thermal and thermomechanical strategies have been proposed to regulate the geometrical arrangement of alpha + beta phases and texture of the alpha phase in an effort to impart the microstructure with concurrent strengthening and toughening. This study explores two potential methods of achieving mechanical enhancement. The first involves the substitution of molybdenum for a portion of vanadium in Ti-64 (alpha + beta, 6.0 Al, 4.0 V weight %, balance Ti), thereby creating a new alloy, termed Ti-639 (alpha + beta, 6.5 Al, 1.7 Mo, 1.7 V, 0.3C, 0.19O, 0.3 Si weight %, balance Ti). Electron backscatter diffraction(EBSD)and transmission electron microscopy are used to study the preservation of the as-received microstructure of TIMETAL 639, owing to the low diffusivity of molybdenum. EBSD texture analysis of solution heat treated TIMETAL 639 shows a marked effect of beta phase on the recrystallization of new globular alpha grains within preexistent colonies, leading to the generation of a distinct depleted bimodal microstructure. Quasi-static compression mechanical testing indicates a measurable increase in mechanical response of the depleted bimodal microstructure,about 90MPa higheryield, with a 6% higher strain at failure, when compared to identically heat treated Ti-64 samples. This alloy design strategy enhances the performance of alpha + beta titanium alloys while foregoing additional prolonged aging heat treatments associated with Ti-64.The second method involves a processing strategy to impart near-net shape structureswith ultraine grain microstructures without resorting to severe mechanical deformation. The proposed strategy relies on utilizing a cyclic rapid heat treatment (CRHT) process to generate refined martensitic microstructures in aerospace grade Ti-64. Analysis of resultant microstructures using EBSDreveals trends in microstructure refinement during successive CRHT iterations. For the given heat treatment parameters, three CRHT cycles yielded an optimum microstructure refinement, by effectively harnessing discontinuous dynamic recrystallization,while diminishing the occurrence of dynamic recovery and continuous dynamic recrystallization.

Dwell time low cycle fatigue (DLCF), low cycle fatigue (LCF), and creep tests were performed at ambient temperature on Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti-6242Si). Test specimens were solution annealed at various temperatures below the beta transus to control the volume fraction of primary alpha. The influence of the changes in primary alpha phase on low cycle dwell time fatigue life were determined and compared to the conventional low cycle fatigue properties of the alloy. A dwell period significantly decreased the number of cycles to failure, but by a decreasing factor with decreasing stress. The increased primary alpha phase present associated with lower solution anneal temperatures significantly increased susceptibility to low cycle dwell time fatigue. It is believed that dwell fatigue sensitivity may be associated with cyclic, ambient temperature, time-dependent plasticity (creep). / Graduation date: 1999

Thesis (M.S.)--University of Akron, Dept. of Mechanical Engineering, 2008. / "August, 2008." Title from electronic thesis title page (viewed 01/13/2010) Advisor, T. S. Srivatsan; Faculty Readers, C. Menzemer, Anil Patnaik, Amit Prakash; Department Chair, Celal Batur; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.