Open Access. Powered by Scholars. Published by Universities.®

Materials Science and Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Masters Theses

Discipline
Institution
Keyword
Publication Year

Articles 271 - 300 of 539

Full-Text Articles in Materials Science and Engineering

The Morphology Of The Cellular Precipitation Reaction In A Pb-3.0 Wt% Sn Alloy, Federico Sequeda Osorio Jan 1972

The Morphology Of The Cellular Precipitation Reaction In A Pb-3.0 Wt% Sn Alloy, Federico Sequeda Osorio

Masters Theses

"The complete development of the cellular precipitation structure at selected grain boundaries in a Pb-3.0 wt% Sn alloy during aging at 34°C and 23°C was investigated by light microscopy. The cellular structure in this alloy consists of lamellae of solute depleted lead solid solution and lamellae of ß tin precipitate. The cellular precipitation reaction begins by local migration of a grain boundary with concomitant grain boundary precipitation of ß tin. The grain boundary bows around the ß tin grain boundary precipitates which then begin to lengthen in the direction of boundary migration thus forming the precipitate lamellae of the cell. …

Go to article

Polynary Silicon Tellurium Glasses, Henry Edward Anthonis Jan 1972

Polynary Silicon Tellurium Glasses, Henry Edward Anthonis

Masters Theses

"The introduction of Ag into Si-As-Te glasses permits the incorporation of Se, otherwise volatile and/or degradable as a constituent in Si-containing chalcogenide glasses. Si-As-Ag-Te-Se glasses exhibit much higher softening ranges and glass transition temperatures than encountered in known chalcogenide systems. A glass Si35As15Ag10Te20Se20 had the viscosity log η =13 at about 500°C, as compared to 370°C for the base glass Si35As25Te40, the viscosity of log η = 9.8 at about 560°C, as compared to 442°C for the base glass Si35As25Te40 …

Go to article

Concentration By Sorting : Feasibility Determination By Radial Distribution Analysis, Robert M. Doerr Jan 1972

Concentration By Sorting : Feasibility Determination By Radial Distribution Analysis, Robert M. Doerr

Masters Theses

"A method was developed for determining certain factors for assessing the feasibility of sorting fragments of an inhomogeneous solid to concentrate a species. These factors are the typical size of zones in which the grade exceeds a selected value, and the recovery potentially achievable by sorting fragments of such size"--Abstract, page iii.

Go to article

Phase Transformations In The System Zro₂-Cao, Damri Sukhotanang Jan 1972

Phase Transformations In The System Zro₂-Cao, Damri Sukhotanang

Masters Theses

"Thermal expansion, thermal hysteresis, and the monoclinic tetragonal phase transformation of ZrO₂ have been studied with high temperature x-ray diffractometry. The initial transformation temperature in pure ZrO₂, on heating, is about 1150ºC. The transformation occurs over a 100ºC temperature range and thermal hysteresis occurs on heating and cooling. The mechanism of the transformation is related to preferred vibrational modes of atoms on the AO -CO plane of the monoclinic structure. Because the monoclinic BO axis is parallel with the tetragonal [110] axis, structural relationships can be seen to be a controlling factor in the transformation. Initiation of …

Go to article

Equilibria Between Moo₂ And Liquid Molybdenum Oxide, Prakash Bakhru Jan 1972

Equilibria Between Moo₂ And Liquid Molybdenum Oxide, Prakash Bakhru

Masters Theses

"The oxygen pressure over solid molybdenum dioxide in equilibrium with liquid molybdenum oxide was determined by transpiration and solid electrolytic galvanic cell methods at 950ºC and 900º, 950º and 1000ºC respectively. The results were compared to those expected from thermodynamic data on the Mo-O system. Possible reactions between MoO₂ and SiO₂ were studied at different oxygen pressures up to 1550ºC. No compound formation or solid solution between MoO₂ and SiO₂ was detected by x-ray diffraction techniques. The phase boundary between MoO₂ and liquid molybdenum oxide was checked by microscopic examination of quenched samples. Equilibration runs were carried out in silica …

Go to article

Mechanism Of Ual₃ To Ual₄ Transformation, Ling Ping Lee Jan 1972

Mechanism Of Ual₃ To Ual₄ Transformation, Ling Ping Lee

Masters Theses

"The UAl₄ compound which forms during the peritectic reaction, Liquid + UAl₃ - UAl₄ , has a long needle-like shape and a characteristic morphology of fish-tail when cut along the long axis. It has an internal core of another phase when cut perpendicular to the needle axis. Because of the interesting similarity between UAl₃ and UAl₄ crystal structures, the peculiar UAl₄ morphology could be explained. The mechanism of UAl₃ to UAl₄ transformation is identified as shear and diffusion controlled transformation"--Abstract, page ii.

Go to article

Thermal Expansion Of Nickel And Iron, And The Influence Of Nitrogen On The Lattice Parameter Of Iron At The Curie Temperature, Jinn-Wen Hwang Jan 1972

Thermal Expansion Of Nickel And Iron, And The Influence Of Nitrogen On The Lattice Parameter Of Iron At The Curie Temperature, Jinn-Wen Hwang

Masters Theses

"By precise X-ray measurements, the lattice parameter of pure nickel (Fisher Co., reagent grade) was found to be 3.52389 Å at 25ºC. At the same temperature, the lattice parameters of iron samples were found to be: 2.86621 Å, 2.86624 Å and 2.86614 Å for purities of 99.999%, 99.985% and 99.9%, respectively. By measuring high angle back reflection lines, the linear coefficients of thermal expansion of both nickel and iron were precisely determined. Both, high purity nickel and iron, exhibited anomalies in their expansion coefficients near their Curie points. This is in agreement with some of the previously reported data. Some …

Go to article

The Electric Field Strength Dependence Of Neutron-Induced Defects In Silicon P-N Junctions, Paul Edward Johnson Jan 1972

The Electric Field Strength Dependence Of Neutron-Induced Defects In Silicon P-N Junctions, Paul Edward Johnson

Masters Theses

"The effect of high electric field strengths (10⁴ to 10⁵ V/cm) present during neutron radiation on the neutron-induced defects is determined by utilizing the high electric field strength inherent in the emitter-base transistion region of an n-p-n transistor. A method is presented for the separation of neutron and gamma effects. Previous theoretical work on the ratio of base current increase to collector current decrease is applied to experimental data. The variations of the space-charge region volume damage introduction rate with neutron fluence and the average electric field strength are determined experimentally in order to obtain a measure of this effect. …

Go to article

A Study Of The System Lithia - Silica, Roy Richard Ramey Jan 1972

A Study Of The System Lithia - Silica, Roy Richard Ramey

Masters Theses

"X-ray intensity and d-spacing measurements were performed upon samples in the system Li₂O-SiO₂. Samples ranged from 0.0 to 28.0 mole percent lithia and were fired for 72 hours at temperatures from 920ºC to 1400ºC. Atomic absorption analyses were made upon the fired samples. Non-equilibrium conditions were prevalent and results are inclusive. Quartz is the stable phase in the high silica field at temperatures below 1050ºC with cristobalite stable above that. The quartz - cristobalite transformation occurs at 950ºC with the cristobalite transforming into tridymite at 1010ºC. There was wide scattering of data at 1000ºC and below. There was no correlation …

Go to article

A Tensi-Volumetric Apparatus: Theory, Calibration, And Use In An Investigation Of The Oxygen Non-Stoichiometry Of Pure Batio₃, Glenn Jon Conger Jan 1972

A Tensi-Volumetric Apparatus: Theory, Calibration, And Use In An Investigation Of The Oxygen Non-Stoichiometry Of Pure Batio₃, Glenn Jon Conger

Masters Theses

"The development of the tensi-volumetric apparatus has been traced to its current position of significance in studies relating to oxide non-stoichiometry. Components of the tensi-volumetric apparatus, especially the capacitance membrane manometer, were examined in detail as were the parameters affecting the performance of such an apparatus. Based on a careful consideration of components and performance, a tensi-volumetric apparatus has been designed, built, and its operation theoretically justified for its particular physical configuration. Results of existing studies of the oxygen non-stoichiometry of barium titanate have been used to predict its behavior during a tensi-volumetric study. Specific analytical procedures developed for use …

Go to article

A Mass Spectrometric Characterization Of Positive Ions Created In Simple Vacuum Diodes Incorporating Oxide Cathodes With Supplementary Analysis Of Background Gases, Larry A. Addington Jan 1972

A Mass Spectrometric Characterization Of Positive Ions Created In Simple Vacuum Diodes Incorporating Oxide Cathodes With Supplementary Analysis Of Background Gases, Larry A. Addington

Masters Theses

"Simple diodes were constructed utilizing oxide cathodes and nickel anodes. The cathodes were obtained by applying a mixture of barium, strontium, and calcium carbonates to a nickel filament and decomposing them to yield the oxides. The products of decomposition were analyzed by monitoring the composition of the background gases in the vacuum chamber. A portion of the flux of positive ions bombarding the cathode during diode operation was analyzed. It was possible to determine the region of origin of the ions and their potential energy at the time of formation. Positive ions of chlorine, fluorine, sodium, potassium, and rubidium were …

Go to article

An Investigation Of Stage I Fatigue Crack Growth In Fcc, Bcc, And Hcp Metals, Marion Anthony Russo Jan 1972

An Investigation Of Stage I Fatigue Crack Growth In Fcc, Bcc, And Hcp Metals, Marion Anthony Russo

Masters Theses

"The objectives of this investigation were to 1) determine if Stage I mode or fatigue crack growth could be extended beyond the 45 degree maximum shear plane in metals having a face-centered, body-centered and hexagonal close pack crystal structure; 2) identify the crystallographic planes or crack propagation in Stage I growth in each crystal structure; 3) characterize the fracture surface topography or Stage I growth in each crystal structure. The test material used for this investigation consisted of alpha brass (70% Cu, 30% Zn), Armco iron and commercially pure titanium which are representative of FCC, BCC, and HCP crystal structures …

Go to article

Mechanical Properties Of Low Carbon Martensite, Allen L. Affolter Jan 1971

Mechanical Properties Of Low Carbon Martensite, Allen L. Affolter

Masters Theses

"Steels of three different compositions were heat treated and tensile tested in order to determine their mechanical properties after heat treatment. All samples had near 0.20 per cent carbon and two manganese levels 0.90 per cent and 1.35 per cent. One group containing the higher manganese level also had small additions of columbium and vanadium. The specimens were too brittle in the as-quenched condition to be loaded to full strength. Maximum strength and ductility were found after short time tempering at low tempering temperatures -- 2 to 15 minutes at 200º to 300ºF. Higher strengths were found at the low …

Go to article

Evaluation Of A Cation Isotopic Substitution Technique In Conjunction With A High Temperature Gas Pycnometer For Determining The Stoichiometry Of Materials, Michael Clair Graves Jan 1971

Evaluation Of A Cation Isotopic Substitution Technique In Conjunction With A High Temperature Gas Pycnometer For Determining The Stoichiometry Of Materials, Michael Clair Graves

Masters Theses

"This study was concerned with the evaluation of a high temperature gas pycnometer, used in conjunction with a cation isotopic substitution technique, for determining the stoichiometry of materials. Three methods were investigated for determining the correction factors for the thermal gradient effects in the gas pycnometer. The correction factors were shown to be dependent on the temperature, the sample volume, and the height of the sample in the sample chamber. Under the conditions of these experiments, the correction factors were shown to be essentially independent of sample grain size and pycnometer atmosphere. The determination of the stoichiometry of cadmium oxide …

Go to article

The Effect Of Cathodic Protection On The Stress Corrosion Characteristics Of 300m Low Alloy Steel, John Pechonick Jan 1971

The Effect Of Cathodic Protection On The Stress Corrosion Characteristics Of 300m Low Alloy Steel, John Pechonick

Masters Theses

"The objective of this investigation was to determine if stress corrosion failure of 300M steel is accelerated by the application of cathodic protection. Testing was conducted on notch tensile specimens that were coated with vacuum cadmium, electroplated cadmium, and vacuum aluminum. All specimens were stressed and placed in an aqueous sodium chloride environment. The failure times for the specimens were monitored and graphs were drawn which characterized the stress corrosion resistance of 300M steel and the cathodic protection systems. Fractography techniques were used to study the failure surfaces to determine the type of failure mechanism. The results of this thesis …

Go to article

Phase Equilibrium And Thermodynamic Study Of Lime-Iron Oxide Solid Solutions, Shin Suk Kang Jan 1971

Phase Equilibrium And Thermodynamic Study Of Lime-Iron Oxide Solid Solutions, Shin Suk Kang

Masters Theses

"The solubility limits of iron oxide in solid lime were determined as a function of oxygen pressure at 1300º and 1400ºG in the system CaO-iron oxide. The stability region of dicalcium ferrite was determined with respect to formation of lime-iron oxide solid solution and liquid oxide. In addition, the hydration behavior in moist air of pure lime and sintered mixtures of lime and iron oxide was also observed. Pelletized samples were equilibrated under known oxygen partial pressures and quenched. Phases present in the quenched samples were identified by microscopy. The solubility limit of iron oxide in CaO is strongly dependent …

Go to article

Factors Affecting The Ductility And Microstructure Of Ti-6al-6v-2sn Titanium Alloy Weldments, Michael John Ball Jan 1971

Factors Affecting The Ductility And Microstructure Of Ti-6al-6v-2sn Titanium Alloy Weldments, Michael John Ball

Masters Theses

"The purpose of the investigation was to study the effect of material thickness, weld heat input and post weld heat treatment on the tensile properties and microstructure of Ti-6Al-6V-2Sn Titanium, and obtain a practical weld/thermal treatment cycle. The objectives were accomplished by electron beam and gas tungsten arc welding 0.060, 0.125 and 0.250 inch thick material and then heat treating at various temperatures and times. Electron beam and gas tungsten arc welding enabled an approximate 4:1 ratio of heat inputs to be utilized. Resultant welded and heat treated material was tensile tested and metallographically examined. Heat treatments involved both air …

Go to article

Evaporation And Condensation Of Zinc, Shailesh Bhanuprasad Vora Jan 1971

Evaporation And Condensation Of Zinc, Shailesh Bhanuprasad Vora

Masters Theses

"Evaporation rates of liquid zinc were determined experimentally within the temperature range of 450º C to 575º C and at argon pressures ranging from 730mm Hg to 130mm Hg. Extrapolated values of these rates are found to be consistent with the previously reported rates obtained by St. Clair and Spendlove at lower pressures. Between 100 microns and one atmosphere pressure rates of evaporation seem to vary according to an equation of the form W = APᴮ, where Pis pressure and, A and B are constants. Similar experiments were performed with brass powders in atmospheres of argon and helium at temperatures …

Go to article

Alkali Mobility And Mechanical Relaxation In Mixed-Alkali Silicate Glasses, James W. Fleming Jr. Jan 1971

Alkali Mobility And Mechanical Relaxation In Mixed-Alkali Silicate Glasses, James W. Fleming Jr.

Masters Theses

"Internal friction and sodium and potassium self-diffusion coefficients for (1-X)Na₂O · XK₂O· 3SiO₂ glasses were measured. Alkali diffusion was measured between 300 and 500ºC using radioactive isotopes and a thin-sectioning technique. Internal friction was measured from room temperature to 500ºC, 0.1 to 2000 Hz. Comparison between alkali diffusion and internal friction data for Na-K glasses with those for other mixed-alkali glasses shows that the mixed-alkali peak is related to alkali mobility. It is concluded that the mechanism for mixed-alkali internal friction is a cooperative rearrangement of dissimilar alkali ions, with the slower moving ion controlling the rate of reorientation"--Abstract, page …

Go to article

Electrolytic Reduction Of Zinc From Acidic Sulfate Solutions, Kenneth Dale Gielow Jan 1971

Electrolytic Reduction Of Zinc From Acidic Sulfate Solutions, Kenneth Dale Gielow

Masters Theses

"Cathode polarization curves were obtained for the electrodeposition of zinc from sulfate solutions with pH 2 and zinc concentrations of 10.0, 40.0, 80.0, and 100.0 gpl zinc. Both pure zinc and pure aluminum were used as cathodes with some difference in results noted. The effect of animal glue additions of 0.01, 0.10, and 0.50 gpl of solution on the cathodic polarization curves and the resulting deposit morphologies were determined. These glue additions correspond to 0.20, 2.0, and 10.0 pounds of glue per ton of zinc deposited, respectively. The slope of the Tafel region of the polarization curves was found to …

Go to article

A Study Of The Void-Strengthening Of Aluminum And Its Nature, Purushottam G. Manusmare Jan 1971

A Study Of The Void-Strengthening Of Aluminum And Its Nature, Purushottam G. Manusmare

Masters Theses

"Strengthening of aluminum by formation of the voids and the nature of resultant strengthening, viz., the temperature and the strain rate dependence of its yield strength were studied. Aluminum wires with 99.999% purity and of 3.1 mm diameter were quenched and heat treated to form voids of the approximate density 10¹³-10¹⁴ voids/cm³ and were tested for their yield strength. Voids in selected samples were observed by transmission electron microscopy using the Hitachi HU-11A microscope. The yield strength of the void strengthened samples was measured at various temperatures from 77ºK to 593ºK using two strain rates, 3.33 x 10⁻²/sec and 1.67 …

Go to article

High Temperature Compressive Creep In Mullite, Peter C. Smith Jan 1971

High Temperature Compressive Creep In Mullite, Peter C. Smith

Masters Theses

"Compressive creep measurements were made on two groups of mullites at temperatures between 1455ºC and 1520ºC. The first group consisted of commercially manufactured mullites. The second group was made up of 7 different mullite compositions spanning the alumina-silica solid solution range from 3Al₂O₃ • 2SiO₂ to 2Al₂O₃ • SiO₂ . Thermal activation energies and stress exponents were calculated for the mullites in the second group. Steady state strain rates taken at 1460ºC under loads of 100 and 110 psi varied between 1.3x10⁻⁴ in/in/hr and 15.4x10⁻⁴ in/in/hr. Activation energies were between 109 Kcal/mole and 204 Kcal/mole. Stress exponents calculated from data …

Go to article

The Pm3m-Fm3m Transformation And Phase Equilibrium In Solid Solutions Of Csc1 With Kc1, Rbc1, And Csbr, John David Weyand Jan 1971

The Pm3m-Fm3m Transformation And Phase Equilibrium In Solid Solutions Of Csc1 With Kc1, Rbc1, And Csbr, John David Weyand

Masters Theses

"Thermal expansion and the Pm3m t Fm3m transition of cesium chloride have been studied with high temperature diffractometry, differential thermal analysis, and heating and quenching techniques. The onset temperature of the transition in pure CsCl, on heating, is 471ºC. There are no observable premonitory effects below the transition temperature and no apparent structural relationships between the polymorphs is apparent. Both phases coexist over a 20º to 50ºC temperature range and equilibrium thermal hysteresis occurs on heating and cooling. Hysteresis behavior is explained by addition of strain energy parameters to the free energy function. Initiation of the Pm3m t Fm3m transformation …

Go to article

Final Sintering Of Cr₂O₃ With Minor Additions Of Mgo And Sintering Of Mgo With Minor Additions Of Cr₂O₃, Gordon E. Jungquist Jan 1971

Final Sintering Of Cr₂O₃ With Minor Additions Of Mgo And Sintering Of Mgo With Minor Additions Of Cr₂O₃, Gordon E. Jungquist

Masters Theses

"The effect of oxygen activity on the sintering of Cr₂O₃ with minor additions of MgO, and of MgO with minor additions of Cr₂O₃ at 1600ºC was investigated. A peak density (99.4% of theoretical) was obtained for high purity Cr₂O₃ by maintaining the equilibrium oxygen partial pressure needed to maintain the Cr₂O₃ phase. The addition of 0.1 wt. % MgO increased the sintered density at the same oxygen pressure to 99.8%. Further MgO additions decreased the density. The density of pure MgO was independent of the PO₂ over the range investigated. Addition of Cr₂O₃ to MgO decreased the density at …

Go to article

The Effect Of 15% Mno On The Phase Relations In The System Cao-Feo-Sio₂ At 1450ºc, Aquil Ahmad Jan 1971

The Effect Of 15% Mno On The Phase Relations In The System Cao-Feo-Sio₂ At 1450ºc, Aquil Ahmad

Masters Theses

"A study was made of the phase relations at 1450ºC in the systems CaO-FeO-SiO₂ and CaO-FeO-SiO₂ -15% MnO, in equilibrium with metallic iron. The stability region of different phases was determined by microscopic examination and electron-beam microprobe analysis of the quenched specimens. The effect of 15% MnO on the liquid saturation boundary of the system CaO-(FeO+MnO)-SiO₂ was discussed in terms of the effect of MnO on slag making reactions in the Basic Oxygen Furnace steelmaking process"--Abstract, page ii.

Go to article

Quenching Defects In Aluminum Plus Ten Atomic Per Cent Zinc, James Thomas Grider Jan 1971

Quenching Defects In Aluminum Plus Ten Atomic Per Cent Zinc, James Thomas Grider

Masters Theses

"This study was undertaken to resolve the conflict which has recently arisen as to the as-quenched microstructure in the Al-Zn system as revealed by thin film transmission electron microscopy. The composition range of most active study has been that from 5 to 15 atomic per cent Zn in superpurity AL. Consequently a composition of 10 atomic per cent Zn was chosen for this study. There are no discontinuties in the phase diagram in this composition range which would influence the above choice. It exists as a single phase solid solution at high temperatures and as a two phase alloy at …

Go to article

Phase Equilibrium And Thermodynamic Study Of The Iron-Copper-Carbon System, Krishna Parameswaran Jan 1971

Phase Equilibrium And Thermodynamic Study Of The Iron-Copper-Carbon System, Krishna Parameswaran

Masters Theses

"Gas carburization experiments were conducted at 950ºC in order to study the phase relations and to determine the activity of carbon in the iron-rich corner of the iron-copper-carbon system. The solubility of graphite in equilibrium with iron-copper alloys was determined at 950º, 1000º, and 1050ºC. The results of gas carburization and graphite solubility experiments at 950ºC were used in constructing an isothermal section of the iron-rich end of the iron-copper-carbon phase diagram, on which are superimposed carbon isoactivity lines. Graphite solubility data at 1000º and 1050ºC were used to construct similar diagrams without the isoactivity lines. The effect of carbon …

Go to article

A Study Of The Dislocation Instability And Reverse Martensitic Transformation In Fe-Ni System, Chung Lim Jan 1971

A Study Of The Dislocation Instability And Reverse Martensitic Transformation In Fe-Ni System, Chung Lim

Masters Theses

"Since the martensitic reaction is a strain transformation, the transformation of the lattice structure can be induced by an external stresses. This also means that the macroscopic total elastic constant should decrease as the temperature is lowered to Ms on cooling. For the reverse transformation an anomalous decrease of the elastic constant is to be expected as the temperature increases to As on heating. In this experiment measurements of the velocity change of an ultrasonic wave in Fe-Ni alloys were carried out for the reverse martensitic transformation. The deviation from the linear relationship of the velocity change as …

Go to article

Fracture Surface Energy Determinations Of High Density Polycrystalline Ceramics, Gene Arthur Pahlmann Jan 1970

Fracture Surface Energy Determinations Of High Density Polycrystalline Ceramics, Gene Arthur Pahlmann

Masters Theses

"Values of fracture surface energy were measured for steatite, zircon, mullite and four densities of alumina. Rods of these high density materials were cut into thin rectangular specimens which were notched and broken in three-point loading. The resulting load necessary for fracture of the specimens was used to calculate the fracture surface energy of the materials. The value for the steatite was around 20,000 ergs/cm². The values for the zircon and mullite were on the order of 13,000 ergs/cm², and the values for the aluminas ranged from 17,000 to 24,000 ergs/cm²"--Abstract, page ii.

Go to article

Imperfections In The Ag-In System (Alpha-Phase) And Lattice Parameters Of Cadmium Oxide, Prafulla Maganlal Vora Jan 1970

Imperfections In The Ag-In System (Alpha-Phase) And Lattice Parameters Of Cadmium Oxide, Prafulla Maganlal Vora

Masters Theses

"This thesis has been divided into two parts, namely, "Imperfections in the Ag-In System (Alpha-Phase)" and "Lattice Parameters of Cadmium Oxide." Imperfections in the Ag-In System (Alpha-Phase): It can be shown -- as in the case of the Cu-In α solid solutions -- that during quenching from the liquid state, strains are produced by the quenching process and, in addition, vacancies are quenched-in, in the Ag-In α-solid solutions. The number of vacancies present, measured by the decreased density of the alloys, is proportional to the indium content up to the solid-solubility limit. Upon heat treatment of the alloys, the thermal …

Go to article

First Prev Next Last