Graduation date: 1952

Thesis (M.F.A.)--Rochester Institute of Technology, 1981. / Typescript. Includes bibliographical references (leaves 20-21).

An investigation has been made of the formation energy, and the activation energy of migration of vacancies in pure silver and its alloys with Cu, Au and Pd. In pure silver the quenched in resistivity rises with increasing quench temperature. In the alloys, however, the quenched in resistivity decreases at first, passes through a minimum and only begins to rise at fairly high quench temperatures. The decrease in the quenched in resistivity in these alloys may be attributed to the destruction of short range order existing in the well annealed specimens. This mechanism is similar to that invoked by both Damask and Korevaar in similar experiments. The annealing characteristics of these quenched specimens also confirm this view. A method, other than that used by Korevaar, for evaluating the formation energy, of a vacancy was used. The results so obtained yield values for Ef of 0.8 ev and Em ranging from .70 ev to 1.02 ev. These results seem reasonable, although it is felt they are insufficiently accurate and extensive to warrant detailed conclusions concerning the effects of specific alloying element s. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

A study has been made of the martensitic transformations occurring in β-phase silver-cadmium and silver-zinc alloys. In silver-cadmium alloys the M(s) temperature was found to change from -44°C to -137°C as the cadmium content changed from 44.2 at. % Cd to 47.0 at. % Cd. Alloys of silver-zinc did not show any martensitic transformation; even on cooling to liquid helium temperature. The thermal martensite in Ag-45 at. % Cd alloy was found to have an orthorhombic structure of the 2H type. This was confirmed by X-ray diffraction and electron microscopy. A spontaneous martensite with a face centred cubic structure was found to occur along the thin edges of perforated specimens used for electron microscopy, because of the relaxation of volume constraints during thinning. In both Ag-45 at. % Cd and Ag-41 at.% Zn alloys a <111> slip direction was found. Also it was shown that Ag-45 at. % Cd alloy was elastically anisotropic, a characteristic very common to β-phase alloys. In both Ag-Cd and Ag-Zn alloys a face centred tetragonal structure could be formed on deforming the specimens by rolling or by tensile deformation. The structure changed to close-packed on severe deformation e.g. by filing. At lower Cd and Zn contents this close-packed structure was face centred cubic, whilst at higher alloy concentrations, this structure was close-packed hexagonal. Pseudo-elasticity was found to occur by stress-induced martensitic transformation. Maximum pseudo-elasticity occurred at temperatures just above A(f) and the actual amount of pseudo-elasticity was found to be dependent on the orientation of the tensile axis. The strain memory effect was studied by deforming specimens below A(f) and then heating. At temperatures below M(f), deformation of the martensite takes place and it is suggested that there is a change in the martensite structure, involving a change from thermal martensite to stress-induced martensite. The experimentally determined habit planes for thermal, stress-induced and deformation martensites were found to agree well with the values obtained using phenomenological theory assuming a {110}<11Ī0> microscopic shear. The 'elastic' elongations accompanying the transformation could be accounted for using the theory. A mechanism suggesting the course of the transformation was developed. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

The effect of single-step and two-step aging treatments on the tensile properties of an Al-6 wt. % Ag alloy and an Al-14 wt. % Ag alloy has been investigated. Results show that the tensile properties of these alloys were approximately the same whether they were given single or two-step aging treatments. Reversion treatments applied to the fully age-hardened Al-14 % Ag alloy after 15 minutes at various temperatures between 200 and 350 °C showed two maxima in the ultimate tensile strength and the yield strength. It is believed that this result was caused by two transformation processes occurring simultaneously: i.e., (1) the coarsening and dissolution of G.P. zones and (2) the growth of the intermediate precipitate, γ'.

Thesis (Master's)--University of California, Berkeley, 1963. / "UC-25 Metals, Ceramics, and Materials" -t.p. "TID-4500 (19th Ed.)" -t.p. Includes bibliographical references (p. 58-61).

No description available.

The effects of single-step and two-step aging treatments on the tensile properties of an A1-4.5%Cu-1.4%Mg- 0.5%Ag alloy have been investigated. Results showed that a maximum ultimate tensile strength of 75 ksi can be attained by single-step aging 24 hr at 170°C. The two-step aging treatments consisting of first aging one week at 80°C followed by aging at 160° and 190°C led to lower strength properties than simple one-step aging. Reversion treatments applied to fully age-hardened alloy resulted in an almost progressive loss of strength in the 250° to 375° range.

Thesis (Ph. D.)--University of Texas at El Paso, 1999. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Fedorov, Andrei; Committee Co-Chair: Degertekin, Levent; Committee Member: Koros, William; Committee Member: Liu, Meilin; Committee Member: Mayor, J. Rhett. Part of the SMARTech Electronic Thesis and Dissertation Collection.