Metallurgy Commons^™

Age Hardening In A Mg-9 Wt.% Al Alloy, J. Beverley Clark

Materials Science and Engineering Faculty Research & Creative Works

The precipitation process and age hardening mechanism in a Mg-9 wt.% Al alloy were studied principally by transmission electron microscopy. This alloy age hardens by the general precipitation of plates of the equilibrium Mg₁₇Al₁₂ phase on the basal plane of the magnesium solid solution matrix. No evidence for the formation of either G.P. zones or a transition lattice of the Mg₁₇Al₁₂ precipitate was obtained. Cellular precipitation occurs competitively with the general precipitation at nearly all age hardening temperatures. In the solution treated condition, basal slip and {101̄2} twins are the principal deformation modes. Precipitation …

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 …

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 Inert Gas Effect On The Rate Of Evaporation Of Zinc And Cadmium, Chu Sheng Wu

Masters Theses

"An experimental study has been made to investigate the effect of argon and helium on the rate of evaporation of zinc and cadmium under one atmosphere pressure at temperatures ranging from 500⁰C to 850⁰C. The experimental results were compared with the maximum rates calculated using the effusion formula as well as with values obtained using three different types of equations based on kinetic theory, diffusion theory, and empirical data. The rate of evaporation in this study appeared to be diffusion controlled. Equations have been derived for expressing the rate of evaporation of zinc and cadmium in both argon and helium …

A Mechanical Metallurgical Method Of Predicting The Springback Tendencies Of A Bent Metal Strip, Jerrold Myles Alyea

Masters Theses

"Attempted substitution of new solid materials and composite metal strips for those materials presently being used in many applications now being pursued vigorously in industry. A serious problem was created because the newly proposed materials do not exhibit the same springback after bending as did the previously used materials in a particular bend angle and radius situation. Elementary bend theory and mechanical metallurgical techniques have been incorporated into a method which can be used to accurately predict the .2% offset yield strength of any proposed rolled-temper solid metal strip and some composite strips when they must exhibit the same springback …

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 …

A Metallographic Study Of Solidification And Segregation In Cast Aluminum-Uranium Alloys, Bruce L. Bramfitt, Hollis P. Leighly

Materials Science and Engineering Faculty Research & Creative Works

The micromorphology and type of segregation in vacuum-cast ingots of aluminum-uranium alloys, ranging from 5 to 30 weight percent, were studied. The microstructural characteristics are similar to those of aluminum-silicon alloys of the same composition range, except that the aluminum-uranium eutectic was identified as having "chevron" and "rhombic spiral" types of morphology. © 1968.

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), …

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 …

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 …

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 …

Relationships Among The Metallurgical Condition, Hardness, And The Electrical Conductivity Of Aluminum Alloys, Richard A. Mueller

Masters Theses

"Electrical conductivity measurements (eddy current determined) combined with indentation hardness measurements are now being used throughout the aerospace industry for nondestructive evaluation of the metallurgical condition of commercial precipitation hardenable aluminum alloys. The review of literature and experiments with two aluminum alloys, 7178 and a 5% Zn-Al binary, have shown that skilled interpretation of hardness-conductivity data depends not only upon a qualitative understanding of the modern wave mechanical theories of electron conduction, but also upon some knowledge of the precipitation reaction kinetics. In particular, the effects of "quenched-in" vacancies and retrogression upon the reaction kinetics must be considered. Studies of …

A Determination Of The Rate Of Evaporation Of Zinc At Atmospheric Pressure., Yu Ming Su

Masters Theses

"Measurements of evaporation rates of zinc in three different residual gases, e.g., argon, carbon monoxide, and hydrogen at one atmosphere pressure, were made. It was found that the rate of evaporation of zinc in one atmosphere of argon was almost the same as that in carbon monoxide, while the rate in hydrogen was almost twice the rate in argon or carbon monoxide. Measurements of evaporation rate of zinc in one atmosphere of argon-oxygen mixtures were also made. The evaporation rate was considerably reduced because the formation of the oxide film retards the zinc vapor escaping from the evaporating surface"--Abstract, page …

A Comparison Of Strength Properties Of Heat Treated Aisi 1065 Steels At High Strength Levels, Robert Lowell Hollenbeck

Masters Theses

"Six AISI C 1065 steels were heat treated and tensile tested in order to evaluate their ductility at high strength levels. Heat treating and tensile testing procedures were developed for use working with these steels at tensile strengths of 300,000 psi and higher. The austenitizing procedure in the hardening operation was found to affect the strength and ductility of the high strength samples. Rapidly heating to the austenitizing temperature followed by an immediate quench produced better properties than slow heating followed by a soaking period before the quench. However, it was concluded that the carbon contents of the steels studied …

A Transmission Electron Microscopy Study Of Some High Strength Plain Carbon Steels, George Joseph Vytanovych

Masters Theses

"Methods of preparing foils of high strength, heat treated, plain carbon steels for examination in the electron microscope by the transmission technique were perfected and are described. Two processes for the initial thinning of a bulk sample were successful. A chemical process was found to be more rapid but not satisfactory for small samples. A mechanical process was slower, but was applicable to the smaller specimens. Electro-polishing the thinned material yielded acceptable foils from which photomicrographs of good quality were obtained. The microstructure of the high strength steel samples showed typical tempered martensite. No reasons for the differences in ductility …

Lattice Constants, Thermal Expansion Coefficients, Densities, And Imperfections In Gold And The Alpha-Phase Of The Gold-Indium System, Vinayak Keshavlal Patel

Masters Theses

"An investigation of structure insensitive properties (lattice parameters, thermal expansion coefficients, densities, and imperfection) of gold and the alpha-phase of the gold-indium system was made. The gold-indium alloys were prepared from high purity (99.999%) gold and indium by melting both metals inside sealed quartz glass tubes which were first evacuated and then filled with helium gas. The solidified alloys were annealed and then examined by x-ray for homogeneity. The lattice constant of 99.999% pure gold at 25⁰C was found to be 4.07894 ł 0.00005 (corrected for refraction) Å. The coefficient of thermal expansion was 13.4 x 10⁻⁶⁰C⁻¹ between 15 and …

Anodic Dissolution Of Zinc In Potassium Nitrate, Martin E. Straumanis, J. L. Reed, William Joseph James

Materials Science and Engineering Faculty Research & Creative Works

The apparent valence of pure zinc dissolving anodically in 3% KNO₃ was determined as a function of current density, temperature, and ultrasonic agitation. The apparent valence of zinc dissolving anodically at 24°C diminishes from 2.01 ± 0.01 at low current densities to 1.86 at about 50 ma and remains fairly constant up to about 80 ma cm−2. This valence is affected to some extent by the preparation, e.g., polishing of the electrode, but is independent of its structure (mono- or polycrystal). Ultrasonic vibrations do not influence the apparent valence at high current densities. In all cases a black film …

Thermal Expansion Coefficients And Lattice Parameters Between 10° And 65°C In The System Gap-Gaas, Martin E. Straumanis, J. P. Krumme, M. Rubenstein

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Synthesis And Structural Determination Of Intermetallic Compounds In The Fe-Ho System, Gerald J. Roe

Masters Theses

"The intermediate phases in the holmium-iron system were investigated by means of X-ray diffraction and metallographic examination. The intermediate phases identified by X-ray diffraction data were HoFe₂ , HoFe₃ , HoFe₅, and Ho₂Fe₁₇.

A new intermediate phase, HoFe₃, was found. HoFe₃ was indexed as hexagonal with lattice parameters of a = 5.084 Å and c = 24.45 Å, and was thought to be of the space group R3̄̄m.

HoFe₂ was formed by a peritectic reaction and its solidus was estimated to be between 1325°C and 1340°C. suggested to be a congruent melting intermetallic compound with a melting point below 1340°C. …

An Investigation Of The Induction Heating Characteristics Of Powdered Susceptors Dispersed In A Non-Conducting Medium, Robert Leon Wright

Doctoral Dissertations

"This investigation determined some of the induction heating characteristics of powdered magnetite, iron and ferrosilicon susceptor dispersed in silica sand which had been coated with thermosetting resin. The powdered susceptor particles in the mixture were heated by the field of an induction coil, consequently heating the resin coated sand and bonding the sand grains together.

It was found that the type, relative amount,and particle size of the susceptor were important variables to be considered in the induction heating characteristics. Hysteresis losses in the susceptor particles, which are a function of the coil current, frequency, and permeability, appear to be the …

The Statistical Mechanics Of Kink Interactions, Michael Brewer Mcneil

Doctoral Dissertations

"Using a potential derived from continuum elasticity, the interactions between kinks on a dislocation line are studied as special cases of the problem of a one-dimensional system of interacting particles. By the use of constant pressure ensembles, the principal kink-interaction problems of physical interest are solved. The application of these solutions to the theoretical analyses of work hardening and internal friction is explored and comparisons made to previous work in which kink interactions were neglected; it is found that, as would be expected, variations of equilibrium kink populations with external stress cannot account for the Bordoni peak, which must therefore …

A Study Of High Strength, Heat Treated Plain Carbon Steels, Ing Shing Chien

Masters Theses

"This work was undertaken as the initial step in a program of studying brittleness in carbon steel that has been heat treated to high strength levels.

The trend in modern technology is toward higher tensile strengths. In practice, only alloy steels are commonly heat treated to very high strength levels. AISI 4340 is one of the more commonly used steels when high strength is desired. It is also becoming almost standard practice to use some of the tool steels or highly alloyed maraging steels for high strength structural components.

For this study high strength in a heat treated steel is …

The Thermodynamics Of The Zno-Fe₂O₃-Fe₃O₄ System, Dennis George Dreyer

Masters Theses

"A study was made of the ZnO-Fe₂O₃-Fe₃O₄ system at 1200ºC using oxygen pressures between 0.1 and 1x10⁻⁴ atmospheres. The results of this study were used to calculate the activities of ZnO, Fe₂O₄, and Fe₃O₄ in the spinel solid solution region of this ternary system. The activities of ZnFe₂O₄ and Fe₃O₄ across the pseudo-binary system were then calculated. The activities of the components in both the ternar and pseudo-binary systems exhibited large positive deviations from Raoult's Law, being more pronounced at the higher Fe₃O₄ content. The free energy, enthalpy, and entropy of mixing of the pseudo-binary system ZnFe₂O₄-Fe₃O₄ at 1200ºC were …

A Study Of The Effect Of Magnetite Additions To Shell Molds On The Surface Quality Of Low Carbon Steel Castings, Robert C. Tooke

Masters Theses

"Shell molds containing additions of ten to fifty percent magnetite, Fe₃O₄, of various particle sizes were cured by induction heating. For comparison, regular shell molds were made using silica and zircon sand. Low carbon steel was cast into all of the molds.

Castings produced from the regular shell molds exhibited poor surfaces due to mold expansion. Magnetite additions eliminated the expansion defects from the casting surfaces.

Excellent surfaces were obtained on the low carbon steel castings with proper selection of the magnetite particle size and the percent of magnetite added. Improper combinations of size and amount …

Hydrogen Absorption And Corrosion Studies Of Zone-Refined Iron, Chang Don Kim

Doctoral Dissertations

"The lattice constants of zone-refined iron filings and iron whiskers are 2.86623 and 2.86626 Å at 25°C respectively. Their thermal expansion coefficients are both the same, 12.1 x 10⁻⁶ /°C at temperatures 10 - 65°C.

The influence of hydrogen on the lattice constant of iron was investigated and it was found that hydrogen has no effect (within the limits of errors) on the lattice constant of iron at room temperature regardless of the charging methods. However, at elevated temperatures hydrogen expands the iron lattice due to increased solubility of the gas. The lattice constant of iron in vacuum and in …

A Study Of The Photomechanical Effect In Silicon, Ronald M. Oglesbee

Masters Theses

"This paper presents the results of an experimental investigation into the photomechanical effect in silicon. The effect was found to be very similar to the electromechanical effect. In both cases the phenomena observed is the softening of a thin surface layer of the material when it is either illuminated or when a current is flowing through the material. An anisotropy was observed in both the hardness and the photomechanical effect. Increasing temperatures tended to "washout" the photomechanical effect. The surface hardness and the photomechanical effect were found to depend heavily on proper surface preparation of the samples, however little dependence …

Detection Of Stress Corrosion Cracking In U-Bend Brass Specimens By An Electro-Mechanical Method, Floyd Elwin Loftin

Masters Theses

"An apparatus was designed and built which held two u-bend specimens. When the specimens were exposed to a corrodent, losses in strength were detected as a result of stress corrosion cracking. The apparatus was used to study time to failure of cartridge brass u-bend specimens exposed to ammoniacal copper sulfate solutions which varied in pH. A minimum time to failure, 1.06 hours, was detected at pH 7.2. The maximum time to failure, for the range studied, was 28.36 hours at pH 7.7.

No useful data were obtained in the range from pH 6.6 - 6.8. thick, black surface coatings were …

The Effect Of Varying Sea Coal Fineness On Sea Coal Activity In Molding Sands, Laurence A. Cooley

Masters Theses

"An experiment was conducted in an attempt to establish a relation between sea coal activity in a facing sand and the particle size of the sea coal added to the sand. It was felt that if a sufficient difference in distribution of volatiles was detected, a correlation between particle size and activity of the sea coal within the test specimens might be established. The lack of positive evidence to support such a relationship is indicative that a variation in particle size does not promote volatile re-deposition within the range of particle sizes investigated for the particular weight per cent of …