Materials Science and Engineering Commons^™

Thermal Fatigue Testing Of Die Casting Die Steels, Kulwant Singh Sabharwal

Masters Theses

"Thermal fatigue is a form of surface failure produced by repeated thermal stresses and is the main cause of die retirement in the die casting industry. A general review of the fundamental and practical aspects of thermal fatigue as encountered in the dies, based on earlier published work, is given and preliminary experiments in an effort to set up a suitable method of testing to study this phenomenon are then described. In the present technique developed to create the thermal conditions experienced by a die steel in aluminum die casting, a small portion of one face of a cylindrical test-piece …

The Effect Of Aging On The Exfoliation Corrosion Characteristics Of 7178 Aluminum Alloy, J. James Slavick

Masters Theses

"The objective of this investigation was twofold: 1) to determine the effect of the quench-to-artificial aging delay period on the exfoliation corrosion of 7178 aluminum alloy subsequently aged at 250F for 24 hours and 2) to determine the effect of an initial aging treatment at 212F on the tensile properties and exfoliation of 7178 aluminum subsequently aged at 250F. Testing was conducted on 0.125 inch thick sheet. Quench-to-aging delay periods of 0 to 28 days, and initial artificial aging treatments at 212F for 24 and 48 hours were investigated. In addition, the effect of overaging T6 material at 320F for …

The Effect Of Small Additions Of Niobium Upon The Corrosion Rates And Electrochemical Potentials Of Iron In Hcl, Hf, And H₂So₄, Richard Lee Jones

Masters Theses

"The valence of niobium ions going into solution was determined by dissolving the metal in hot HF and measuring the volume of hydrogen evolved. The corrosion rates of Nb, NbH_x, Fe and Fe - Nb alloys were determined in various concentrations of NCl, H₂SO₄ and HF. The Fe and Fe - Nb alloy samples were made by using powder metallurgy techniques. It was found that a metal skin was produced on the surface of iron corrosion samples if the carbon content of the surface layer was lower than that of the core of the sample. The lower carbon …

Internal Friction Of Phase Separated Glasses, Scot Walter Taylor

Masters Theses

"The large internal friction peak observed in a 10Li₂O·10Na₂O·80SiO₂ glass was studied as a function of the degree of phase separation. Transmission electron microscopy was used to evaluate the type and degree of phase separation. No observable changes in the temperature position or height of the internal friction peak were observed at successive stages of phase separation. Phase separation of a mixed alkali borosilicate glass also produced no changes in the internal friction peaks. Phase separation is not considered responsible for the large internal friction peak observed in mixed alkali glasses"--Abstract, page ii.

A Continuous Method For Determination Of The Evaporation Rate Of Zinc, Paul Alan O'Neill

Masters Theses

"A method for determination of the evaporation rate of zinc using a continuous recording balance has been devised. Tests were carried out under an inert gas over the range 600°C to 750°C with a total pressure of 1 atmosphere. It was found that the rate of evaporation doubled with an increase of 50°C in this range. Scanning electron microscope photographs show the crystalline nature of the condensate and the presence of a thin oxide layer on some solidified test samples. This oxide layer reduced the rate of evaporation by retarding the zinc vapor escape from the evaporating surface"--Abstract, Page iii.

Anodic Oxidation Of Pure And D.S. (Dispersion Hardened) Lead In Sulfuric Acid Solutions, Rafael San Martin Aldazabal

Masters Theses

"The anodic oxidation of pure and dispersion hardened lead in 1 N H₂SO₄ was studied potentiostatically in the range - 0.28 to 2.0 volts (SHE). The anode surfaces were observed at various stages on a scanning electron microscope and x-ray diffraction techniques were used to determine the phases present. It was established that by oxidation up to 0.25 v only PbSO₄ is obtained. At potentials between 0.25 and 1.57 v, PbO (tetragonal) is formed beneath the lead sulfate layer. At potentials above 1.57 up to 2.0 v, a layer of ßPbO₂ forms in the outermost part of the anode underlying …

The Effect Of Thermal-Mechanical Processing Of The Exfoliation Corrosion Resistance Of An Aluminum-Zinc-Magnesium-Copper Alloy, James Lawrence Spehr

Masters Theses

"The objective of this investigation was to evaluate the effect of thermal-mechanical processing on the exfoliation corrosion resistance of an aluminum-zinc-magnesium-copper alloy. the aluminum alloy used was commercially available 7178 alloy in two thicknesses, 0.390 inch thick and 0.250 inch thick. this material was reduced 10, 25 and 40% in thickness in both the annealed and solution heat treated conditions. The material was then aged to a high strength condition, T6, or T8, in the case of the material reduced in the solution heat treated condition. The effect of the thermal-mechanical processing on the exfoliation corrosion resistance was then evaluated …

Establishment Of A Torsion Pendulum And Its Evaluation, Ashwin Kantilal Ghatalia

Masters Theses

"A torsion pendulum apparatus has been constructed. The pendulum has been evaluated by studying the Zener relaxation in α brass. Three wire specimens of commercial alloy of Cu-Zn were used and the value of log decrement has been obtained by the method of free decay of the oscillations. The known Zener peak was observed"--Abstract, page ii.

Additional Magnetic Disaccommodations In Ternary Iron Base Alloys, R. H. Graham, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

On The Influence Of Surface Roughness On The Determination Of Diffusion Constants, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Isotope Effect Of Carbon Diffusion In An Fe-Si Alloy, Manfred Wuttig, E. T. Yen

Materials Science and Engineering Faculty Research & Creative Works

The isotope effect of carbon diffusion in dilute iron silicon alloys containing 28Si and 30Si has been measured below room temperature using the Dis accommodation technique. The time dependence of the reluctivity has been analyzed in terms of two relaxation processes which are due to the reorientation of carbon interstitials in Fe-Fe and Fe-Si sites respectively. The ratio of the relaxation times of the two carbon isotopes 13C and 12C τ13/τ12 is 1.037 for the former and 1.007 for the latter process in the Fe+28Si alloy. The ratios of the relaxation times of the same carbon isotope 12C contained in …

Diffusion Of Iron And Cobalt In Nickel Single Crystals, Charles Frederick Heuer

Doctoral Dissertations

"Diffusion coefficients of iron-59 in nickel have been determined in the temperature range 815°C to 1200°C. The temperature dependence can be represented by an Arrhenius type relationship,...The effect of the isotopic mass on the diffusion coefficient of cobalt in nickel has also been investigated. The isotope effect parameter, E, was found to vary from .26 to .84 over the temperature range 970.5°C to 1200°C. Both results are consistent with the single vacancy mechanism of diffusion. No evidence of divacancy contributions to the mass transport has been found"--Abstract, Page i.

The Iron-Holmium Binary System And Related Magnetic Properties, Gerald J. Roe

Doctoral Dissertations

"The iron-holmium phase diagram was investigated to determine the alloying behavior of these two metals and to determine the magnetic properties of some of the iron-holmium alloys which formed intermediate phases. The iron-holmium binary system was determined by three experimental techniques, differential thermal analysis (DTA), x-ray diffraction, and metallography. A phase diagram with three eutectic points and four intermediate phases was constructed from the experimental data. The two phases, Ho₆Fe₂₃ and Ho₂Fe₁₇, melted congruently at 1322⁰C and 1343⁰C respectively. HoFe₂ and HoFe₃ melted incongruently at 1288⁰C and 1293⁰C respectively. Neutron diffraction investigations were made on the intermediate phases Ho₆Fe₂₃ and …

Calorimetry Of Room Temperature Deformed Copper, George Juri Filatovs

Doctoral Dissertations

"An adiabatic anisothermal differential calorimeter for the study of room temperature deformed 99.999% pure copper has been constructed. An annealed and a deformed specimen were heated at a constant rate in adiabatic surroundings and the differences in energy released between samples was obtained. The control circuits were automatic. Deformation was by elongation ranging from 12 to 40%, and the corresponding energy found was from 1.9 to 5.3 calories/gram-atom. No recovery energy was found. The results obtained generally agree with published results and, in particular, verify Gordon's isothermal annealing results. It is proposed that the criteria for the presence of recovery …

Surface Self-Diffusion On Nickel (111) By Radioactive Tracers, James Ronald Wolfe

Doctoral Dissertations

"Surface self-diffusion coefficients have been measured by a radioactive tracer method over the temperature range 614⁰ to 840⁰C on nickel (111) surfaces characterized by LEED. Previously unrecognized tracer evaporation during surface diffusion resulted in restricted spreading of the tracer at higher temperatures. A theoretical treatment of the tracer evaporation phenomenon is presented and subsequently used in the analysis of the data. The temperature dependence of the surface self-diffusion coefficient (D_s) for nickel (111) can be represented, over the experimental temperature range, by a single Arrhenius type relationship...Arguments are presented to justify an adatom surface diffusion mechanism which is …

Influence Of Continuous Precipitation Upon The Growth Kinetics Of The Cellular Reaction In An Al-Ag Alloy, H. I. Aaronson, J. B. Clark

Materials Science and Engineering Faculty Research & Creative Works

The influence of the prior formation of a continuous precipitate upon the growth kinetics of the cellular reaction has been evaluated in an Al-17.9 wt. % Ag alloy. The continuous precipitate, in the form of intragranular plates of the γ′ transition phase, was shown to have reduced the upper bound of the driving force for the cellular reaction from the silver content of the untransformed alloy to that corresponding to the coherent solvus. When this reduction (≥ 98 %) is taken into account, the growth of cells is found to be controlled by cell boundary rather than by volume diffusion …

Isotope Effect Of Interstitial Diffusion Of Carbon In A Dilute Fe-Si Alloy, Edward T. Yen

Masters Theses

"The isotope effect of carbon interstitial diffusion in a Fe-2.75at%Si alloy has been measured at -3.10°C using the disaccommodation technique. The disaccommodation has been analyzed in terms of two relaxation processes which are discussed on the basis of the reorientation mechanism of carbon interstitials at Fe-Fe sites and Fe-Si sites respectively. The ratios of the relaxation times [tau]₁₃/[tau]₁₂ are 1.0382 for the former and 1.0072 for the latter relaxation process. This result is discussed on the basis of many-body reaction rate theory"--Abstract, page ii.

Corrosion Rates And Electrokinetics Of Cobalt And Cobalt-Rich Cobalt-Iron Alloys In Sulfuric And Hydrochloric Acids, Cheng Tzong Horng

Masters Theses

"Corrosion rates for Co and Co-rich Co-Fe alloys were determined in sulfuric and hydrochloric acids under both deaerated and oxygenated conditions. For the purpose of comparison, corrosion rates of Co cut from metal sheet were also determined in the same environments as those of sintered alloys. Sintered alloys were inferior to solid Co as corrosion resistant materials. It was found that the surface was more corrosion resistant than the interior. Thus after long exposure to the corrosive acid, the samples became porous inside while the surfaces remained substantially intact. Oxygen had a pronounced effect in accelerating the corrosion of Co …

Influence Of Nobler Metal Salt Additions Upon The Dissolution Rate Of Aluminum In Hydrofluoric Acid, Barry L. Basden

Masters Theses

"The rate of dissolution of aluminum in 2N HF upon the addition of nobler metallic salts was studied. Aluminum corrodes in HF due to the acid's ability to dissolve the protective oxide present on the surface. Rates were measured by the hydrogen evolution method. Salt additions of AgN0₃, CuSO₄, HAuC₄, and PtCl₄ to aluminum dissolving in 2N HF resulted in the electroless deposition of more or less coherent metals (from the salts mentioned) on the aluminum surface. The dissolution rate initially decreased in all of the cases and was attributed to the "blanketing effect" of the deposits. Ensuing increases of …

Pressure Welding Of Continuously Cast Nodular Iron, Gerald W. Wille

Masters Theses

"The objective of this study was to determine the feasibility of using pressure welding as a joining technique for swaged nodular iron.

Test pressure welds were produced with swaged continuous cast nodular iron at temperatures between 1750⁰F and 2050⁰F with welding pressures between 15,900 psi and 51,400 psi using an induction coil to heat the weld zone.

Pressure welds of greater strength than the as-received nodular iron were produced by swaging the material before welding. The optimum welding parameters were a temperature of 2050⁰F with a welding pressure of 46,700 psi.

On the basis of these tests it is concluded …

Kinetics Of The Formation Of Strontium Zirconate, W. H. Parker

Masters Theses

"The decomposition rate of strontium carbonate (SrC0₃) was measured using a TGA apparatus. It was found to deviate slightly from zero order classical reaction. The rate of formation of strontium zirconate (SrZr0₃) from zirconium oxide (ZrO₂) and strontium oxide (SrO) in the form of the decomposition product of SrCO₃ was measured using quantitative x-ray diffraction for mineralogical analysis. It was found to most nearly follow the Zhuravlev-Lesokhin-Tempel' man rate equation. The rate of decomposition of strontium carbonate was found to be more rapid than the rate of formation of strontium zirconate such that for the most part strontium oxide is …

The Effect Of Prior Cold Work On The Pressure Welding Of Ferritic Nodular Iron, Ronald Morris Ledbetter

Masters Theses

"The purpose of this investigation was to determine the effect of prior cold work by swaging on the pressure welding of ferritic nodular iron. Test pressure welds were produced from continuously cast ferritic nodular iron in the as cast condition and with prior cold work of 20, 30, 40, and 50 per cent reductions in area. Welding pressures of 23,500 psi, 35,300 psi, and 47,100 psi were employed. All welds were made at interface temperatures of 2000°F. Welds made with the as cast material at high welding pressures possessed relatively low tensile strengths due to the creation of planes of …

Lattice Parameters, Coefficients Of Thermal Expansion, Densities, And Lattice Perfection Of The Copper-Indium Primary Solid Solutions, Lin Sheng Yu

Masters Theses

"Precise measurements of lattice parameters and densities of the alpha-phase Cu-In solid solutions were made at temperatures of 25°C. The thermal expansion coefficients between 15 and 65°C, the solid solubility of In in Cu at 650°C, and the soundness of crystal structure resulting from alloying were determined. The Cu-In alloys were prepared from high purity (99.999%) Cu and In by melting both metals inside evacuated quartz tubes. The solidified alloys were annealed and then examined by X-ray for homogeneity...The slowly solidified alpha-phase alloys gave densities lower than the theoretical (X-ray) values due to the presence of shrinkage microporosity. This density …

The Damage Assessment Of Thermally Shocked High Density, High Purity Aluminum Oxide, John H. Ainsworth

Doctoral Dissertations

"The traditional approach to thermal shock testing in brittle materials has been to determine the temperature difference required to nucleate cracks in these materials. Recent work has indicated that the degree of damage after crack nucleation should be an additional consideration. The degree of damage resulting from cooling thermal shocks has been the primary consideration of the present work. Test specimens of two geometries: long, solid rods and short, solid cylinders were quenched from selected temperatures into ice water. The degree of damage was determined through strength measurements and sonic damping analysis. Initial damage occurred at a temperature difference above …

Effect Of Micelles On Flotation Of Metal Ions, Uriel Michael Oko

Doctoral Dissertations

"A study of the anionic surfactant, sodium dodecyl sulfate (SDS), and the dependency of the adsorption of divalent metal counterions such as copper and zinc at the air-water interface on its concentration in the solution, was undertaken in order to better understand the process of ion flotation. The study is divided into two broad categories, the first of which consists of the evaluation of the extent of aggregation of the surfactant molecules into micelles, and the effect of the divalent metal counterion concentration on this aggregation and on the critical concentration at which micelles start forming (cmc). This was accomplished …

Decomposition Of Cr(Oh)₃ To Form Active Cr₂C₃, Timothy A. Clancy

Doctoral Dissertations

"This study was concerned with the sinterability of Cr₂C₃ powders produced by the calcination of a Cr(OH)₃ gel. The decomposition of the gel was investigated by thermogravimetric analysis, X-ray analysis and microscopic examination. Comparison was made between the size of crystallites as determined by X-ray line broadening and the size of aggregated particles as determined by independent means. These lineal measurements were compared to surface area measurements on the calcined powders. The degree of sinterability was judged from the density measurements on Cr₂C₃ pellets fired under air, oxygen and nitrogen atmospheres. Energies of activation of 25 and 20 kilocalories per …

Compressive Creep Of Basic Refractories, Maurice E. Green

Masters Theses

"The microstructure and mineralogical composition of direct bonded, 50 wt.% magnesia - 50 wt.% chrome ore refractory compositions containing controlled additions of silica were correlated with their compressive creep behavior in the temperature range 1450⁰ to 1550⁰C under stresses of 100 to 175 psi. Steady state creep rates were determined from the linear regression of the steady state regions of deformation on time. Apparent activation energies and deformation flow characteristics were determined from the temperature and stress dependence of the steady state creep rates. Silica contents up to 3.5 wt.% increased the amount of direct intergranular bonding which decreased the …

Interstitial Solute Trapping In Irradiated And Quenched Iron, M. (Manfred) Wuttig, J. T. Stanley, H. K. Birnbaum

Materials Science and Engineering Faculty Research & Creative Works

The interaction of interstitial carbon and nitrogen solutes with defects produced by low temperature neutron irradiation and by quenching was studied in high purity and Ferrovac E iron. Magnetic Dis accommodation techniques were applied to determine the interstitial solute content after irradiation and upon annealing. Doses of about 1017 neutrons/cm2 caused the trapping of about 20 ppm (atomic) interstitial solutes at 65 (carbon) and 40°C (nitrogen). Trapping of carbon in a Ferrovac E iron alloy occurred during a fast quench from 880°C. After trapping, the interstitial solutes reappeared in solid solution at 300 (carbon, neutron irradiation), 200 (nitrogen, neutron irradiation), …

Cutting Nbs Budget, Norbert J. Kreidl

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Current Density-Anodic Potential Curves Of Single Crystal Gaas At Low Currents In Koh, Martin E. Straumanis, J. P. Krumme, William Joseph James

Materials Science and Engineering Faculty Research & Creative Works

Single p-type, GaAs crystals of high purity, Zn doped, were used to determine whether or not the inverse octahedral {111} faces show potential differences and various rates of anodic dissolution. The Ga{111}, As{111}, {110}, and {100} faces, were polished, etched, and etch-polished with concentrated H₂SO₄ + H₂O₂, and immersed in IN KOH. The Ga{111} faces were found to be the most noble with respect to rest and anodic dissolution potentials. The potential difference between the inverse {111} faces was as large as 0.14v for the rest and 0.123v for the dissolution potentials. The …