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Articles 1711 - 1740 of 2244

Full-Text Articles in Materials Science and Engineering

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 …

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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 …

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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.

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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 …

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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. …

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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 …

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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 …

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Low Temperature Lattice Parameters And Expansion Coefficients Of Ai2au And Lif Gruneisen Constants Of Lif, Martin E. Straumanis, Jayant S. Shah Jan 1972

Low Temperature Lattice Parameters And Expansion Coefficients Of Ai2au And Lif Gruneisen Constants Of Lif, Martin E. Straumanis, Jayant S. Shah

Materials Science and Engineering Faculty Research & Creative Works

There is no difference in the thermal expansion behavior of an intermetallic compound (Al2Au) and of an ionic (LiF), except in the magnitude of the expansion coefficients, which for both compounds upon cooling below 40°K approach zero. The lattice parameters of the two compounds mentioned decrease uniformly and without anomalies with lowering the temperature, approaching a constant value below 40°K. The a–T relationship between 40 and 180° is given in form of equations. A pump working on the Joule‐Thomson principle was used for cooling. The GRÜNEISEN parameter, γ, of LiF between 40 and 180°K is a constant, contrary to theoretical …

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Irradiation Enhanced Decomposition Of A Nickel-Carbon Solid Solution, B. L. Shriver, Manfred Wuttig Jan 1972

Irradiation Enhanced Decomposition Of A Nickel-Carbon Solid Solution, B. L. Shriver, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

This investigation was performed to determine the effects of room temperature neutron irradiation on the distribution of carbon in a nickel-0.3 wt.% carbon alloy. The experiment consisted of comparing the amount of carbon in solid solution and the internal stresses of both unirradiated and irradiated (1013 fn-cm-2 < ΦF < 1018 fn-cm-2) samples following isochronal anneals between 100 and 1200°C by using the magnetic Dis accommodation technique. The results indicate that the amount of carbon remaining in solid solution decreases with increasing neutron dose. At temperatures below 200°C this is due to the trapping of carbon by mobile irradiation-produced defects. Between 200 and 600°C the formation of metastable carbides is enhanced by the presence of irradiation-produced defects. No differences are observed in irradiated and unirradiated samples above 600°C. © 1972.

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Polynary Telluride Glasses Containing Silver, H. E. Anthonis, N. J. Kreidl Jan 1972

Polynary Telluride Glasses Containing Silver, H. E. Anthonis, N. J. Kreidl

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Thermal Expansion Behavior Of Silicon At Low Temperatures, Jayant S. Shah, Martin E. Straumanis Jan 1972

Thermal Expansion Behavior Of Silicon At Low Temperatures, Jayant S. Shah, Martin E. Straumanis

Materials Science and Engineering Faculty Research & Creative Works

Lattice parameters, thermal expansion coefficients and Grüneisen parameters of silicon are determined by an X-Ray diffraction method in the temperature range of 180-40 K without the use of liquid gases. Thermal expansion of silicon becomes negative below 120 K which is discussed in terms of its lattice vibrations and crystal structure. © 1972.

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Nonstoichiometry In Batio3, G. J. Conger, Harlan U. Anderson Jan 1972

Nonstoichiometry In Batio3, G. J. Conger, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Dissolution Potentials And Activation Energies Of Insb Single Crystals, Martin E. Straumanis, Lih Da Hu Jan 1972

Dissolution Potentials And Activation Energies Of Insb Single Crystals, Martin E. Straumanis, Lih Da Hu

Materials Science and Engineering Faculty Research & Creative Works

The rest (or corrosion) and dissolution potentials of InSb single crystals in HC1 were determined. There is no potential difference (within error limits) between the inverse {111} faces in pure HC1. A difference of up to 44 mV and more develops as soon as the InSb electrode is anodically dissolved. The potential becomes less noble in the sequence In{111}, {100}, {110}, Sb{111}. The Tafel relationship is observed over three decades of current density. With additions of FeCl3, FeCl2, K3Fe(CN)6, K4Fe(CN)6, H2C4H4O6 to 2N HC1, the anodic potentials of both inverse {111} faces are shifted to more active values; the e'H …

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Comment On The Nature Of The Disaccommodation In Hcp Co-C Alloys, J. Keiser, Manfred Wuttig Jan 1972

Comment On The Nature Of The Disaccommodation In Hcp Co-C Alloys, J. Keiser, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Activation Volumes Of Carbon Diffusion In Fcc Iron-Nickel Alloys, J. Keiser, Manfred Wuttig Jan 1972

Activation Volumes Of Carbon Diffusion In Fcc Iron-Nickel Alloys, J. Keiser, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

The Dis accommodation technique was used to determine the activation volume of carbon diffusion, ΔV, in six fcc iron-nickel alloys. Measurements were made at temperatures ranging from 68 to 90 °C and pressures up to 6 kbar on samples having a nickel content between 31 and 63 at.%. A maximum activation volume of 3.9 cm3/mole was found at 34 at.% nickel. The compositional dependence of ΔV is satisfactorily reproduced by a magnetic-energy continuum model in which it is assumed that the activation free energy of diffusion is essentially ferromagnetic in origin. © 1972 The American Physical Society.

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Pbo Transformation Induced By Water, Charles A. Sorrell Jan 1972

Pbo Transformation Induced By Water, Charles A. Sorrell

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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The Morphology Of Cellular Precipitation In Aluminum Rich Aluminum-Silver Alloys, Santiago Ibarra Jr. Jan 1972

The Morphology Of Cellular Precipitation In Aluminum Rich Aluminum-Silver Alloys, Santiago Ibarra Jr.

Doctoral Dissertations

"The morphology of cellular precipitation in Al-29.8wt%Ag alloy has been investigated in bulk specimens by transmission electron microscopy and in solution treated specimens by means of hot stage microscopy. Both cellular and general precipitation were observed to occur simultaneously in quench-aged and isothermally aged alloys. By studying the early stages of precipitation in the hot stage, the mechanism for the growth of cells in Al-Ag alloys was developed. According to this mechanism, the grain boundary allotriomorphs begin to form, the boundary then interacts with the allotriomorphs by bowing, and then either trailing precipitation forms on the allotriomorphs or new lamellae …

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A Study Of The Solid Regions In The System Zr-Te, Frances Dolores Jenkins Jan 1972

A Study Of The Solid Regions In The System Zr-Te, Frances Dolores Jenkins

Doctoral Dissertations

"Relative intensity measurements of X-ray powder diffraction lines were made of compositions in the region ZrTe₀.₅ to ZrTe₂.₀, fired between 600º and 817ºC in evacuated sealed tubes. The experimental relative intensities of samples between ZrTe and ZrTe₂ were compared with values calculated for several theoretical models with different Zr vacancy ordering schemes and Te vacancy concentrations. The most probable structural model for compositions in the range ZrTe to ZrTe₁.₅ is one in which the number of Zr vacancies located at z = 0 ranges from 0% to 30%, with the concentration of Te vacancies ranging from 0 to 35%. A …

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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 …

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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 …

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Thermal Expansion Of Tungsten At Low Temperatures, Jayant S. Shah, Martin E. Straumanis Dec 1971

Thermal Expansion Of Tungsten At Low Temperatures, Jayant S. Shah, Martin E. Straumanis

Materials Science and Engineering Faculty Research & Creative Works

Lattice parameters, thermal expansion coefficients, and Grüneisen parameters of tungsten are determined by an x-ray method in the temperature range of 180-40 K without the use of liquid gases. Lattice parameters are expressed as a function of temperature. Thermal-expansion coefficients decrease with temperature and show no anomaly in contrast to a hypothesis proposed by Featherston and Neighbours. Grüneisen parameters γ are decreasing with temperature in accordance with the theoretical predictions. © 1971 The American Institute of Physics.

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Thermal Lattice Expansion Of Various Types Of Solids, Jayantkumar Shantilal Shah Jan 1971

Thermal Lattice Expansion Of Various Types Of Solids, Jayantkumar Shantilal Shah

Doctoral Dissertations

"Thermal lattice expansion studies of various types of solids were carried out in this investigation and were corelated to their crystallographic and various other properties. The advantages and limitations of various methods of studying thermal expansion are discussed in detail. A new design for a versatile low temperature camera to study expansion by an X-ray method is proposed. The thermal lattice expansion of silicon was negative below 119ºK. This behavior is discussed in terms of crystal structure and interatomic bonding. Diamond exhibits no anomalous thermal expansion. Lattice parameter data for many metals at low temperatures are reported for the first …

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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 …

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Structure And Properties Of Silver Borate Glasses, Edward Nashed Boulos Jan 1971

Structure And Properties Of Silver Borate Glasses, Edward Nashed Boulos

Doctoral Dissertations

"Clear glasses form in the system Ag₂O-B₂O₃ up to about 35 mol.% (65 wt.%) Ag₂O. Infrared absorption, thermal expansion and density data indicated an analogy to the Na₂O-B₂O₃ system. Pentaborate-triborate group pairs appear to be formed upon the addition of Ag₂O to B₂O₃ up to 20 mol.% Ag₂O and diborate groups from 20 to 33 mol.% Ag₂O. This interpretation is supported by the comparison of the infrared absorption spectra of quenched and crystallized glasses. One crystallization product ,Ag₂O.4B₂O₃, has been identified previously. A new compound starts to appear at 28 mol.% Ag₂O. Silver is generally present as a network modifier …

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X-Ray And Neutron Diffraction Study Of The Holmium-Iron System, Michael Fred Simmons Jan 1971

X-Ray And Neutron Diffraction Study Of The Holmium-Iron System, Michael Fred Simmons

Doctoral Dissertations

"Neutron diffraction and x-ray powder studies have been made of holmium-iron intermetallic compounds. The magnetic moments of Ho and Fe are in good agreement with measured spontaneous magnetization assuming a ferrimagnetic model with the Ho moments antiparallel to the Fe moments. The magnetic moments of the Fe atoms are found to be localized and thus independent of the rare earth content in the alloys. In contrast to HoCo₃, (00ℓ) type magnetic peaks in the neutron diffraction patterns are still prevalent at room temperature and gradually decrease as the Curie temperature is approached. This fact indicates that the easy direction of …

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Liquid Viscosity Measurement Using A Buret: An Instructional Technique, Charles A. Sorrell Jan 1971

Liquid Viscosity Measurement Using A Buret: An Instructional Technique, Charles A. Sorrell

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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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 …

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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 …

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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 …

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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 …

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