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Articles 1771 - 1800 of 2628

Full-Text Articles in Metallurgy

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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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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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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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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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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The Effect Of Impurities And Additives On The Electrowinning Of Zinc, Haruhisa Fukubayashi Jan 1972

The Effect Of Impurities And Additives On The Electrowinning Of Zinc, Haruhisa Fukubayashi

Doctoral Dissertations

"The effect of various impurities, commonly found in zinc electro-winning solutions, on the surface morphology of deposited zinc was investigated. Individual additions of the impurities Al, Ag, Cd, Co, Cr, Cu, Ge, Mn, Ni, Sb, Sn, Ti, PbO₂ , PbSO₄, and HCl were studied. In a few cases additives of animal glue, gum arabic, and Na₂SiO₃, were used individually or in combination, to determine their effect on the surface structure of the deposited zinc. Comparisons were then made with deposits from a pure electrolyte consisting of H₂SO₄ and Zn⁺², 200 and 65 g/l, respectively. The zinc was deposited on a …

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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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Grain Boundary Diffusion In Ionic Crystals, Kulwant Singh Sabharwal Jan 1972

Grain Boundary Diffusion In Ionic Crystals, Kulwant Singh Sabharwal

Doctoral Dissertations

"The diffusion of ¹³¹I in single crystals and along the tilt grain boundaries of pure and calcium chloride doped (142±5 ppm) bicrystals of sodium chloride, grown by Czochralski technique, was investigated using a microtome sectioning technique. Results on bulk diffusion in pure NaCl agree well with the results of earlier investigators and are represented by the D=(504 cm²/sec)exp (-2.27 ev/kT). Enhanced diffusion of ¹³¹I is observed along the grain boundaries and the presence of the dopant lowers the grain boundary diffusivity over the entire temperature range of 430ºC - 570ºC studied in the present investigation. Thermal activation and electrical polarization …

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Effects Of Cr-Plating And Environment On The Cracking Of Low Alloy Steels At High Temperatures, Robert C. Tooke Jan 1972

Effects Of Cr-Plating And Environment On The Cracking Of Low Alloy Steels At High Temperatures, Robert C. Tooke

Doctoral Dissertations

"The cracking of low alloy Cr-Mo-V steels under cyclic stress at 1000-1100°C. was studied using a specially designed test apparatus. The results obtained from specimens plated with hard chromium are compared to those of unplated specimens. Tests conducted in gas mixtures of carbon monoxide and carbon dioxide showed that a high CO/CO2 ratio retards cracking in both plated and unplated specimens. Both external and internal oxidation are used to explain these results. Inherent microcracks in the hard chromium plating promoted cracking in all CO/CO2 environments. It was also found that these steels are severely embrittled in the presence …

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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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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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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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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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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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On The Interaction Of Aluminium And Iron Calcium Borate Glasses And Its Effect On The Properties Of Their Composites, Sherif K. Arif May 1971

On The Interaction Of Aluminium And Iron Calcium Borate Glasses And Its Effect On The Properties Of Their Composites, Sherif K. Arif

Archived Theses and Dissertations

No abstract provided.

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The Anodic Dissolution Reaction Of Insb: Etch Patterns, Electron Number, Anodic Disintegration, And Film Formation, Martin E. Straumanis, Lih Da Hu Jan 1971

The Anodic Dissolution Reaction Of Insb: Etch Patterns, Electron Number, Anodic Disintegration, And Film Formation, Martin E. Straumanis, Lih Da Hu

Materials Science and Engineering Faculty Research & Creative Works

The etching behavior of the inverse {111} planes of undoped, semiconducting, n-type, InSb single crystals was explored. Depending upon the etchant, including anodic dissolution, various etch patterns were obtained on the inverse planes. In general, the etch pits on the In{111} plane were round, and the face was shiny, whereas the face of the inverse plane was dark and rough. The rates of dissolution in the electrolytes used were very low, especially in absence of oxidizers. The components dissolve as In3+ and Sb3 +. At current densities above 40 or 60 mA cm-2 (on Sb{111} or In{111}), growth of a …

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A Magnetic Aftereffect In Dilute H.C.P. Co-C Alloys, J. R. Keiser, Manfred Wuttig Jan 1971

A Magnetic Aftereffect In Dilute H.C.P. Co-C Alloys, J. R. Keiser, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

A magnetic Dis accommodation in dilute h.c.p. Co-C alloys has been observed around 90°C. The thermally activated process giving rise to the Dis accommodation is characterized by an activation energy of 26 kcal mole-1 and an attack frequency on the order of 10+13 sec-1. An application of the selection rules shows that the Dis accommodation cannot be caused by the redistribution of tetrahedral or octahedral interstitials or any nearest neighbor interstitial pairs as long as the defects interact linearly with the internal magnetic field. © 1971.

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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 …

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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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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 …

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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 …

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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 …

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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 …

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Anodic Dissolution Of Beryllium In Anhydrous Media, William Joseph James, Martin E. Straumanis Jan 1971

Anodic Dissolution Of Beryllium In Anhydrous Media, William Joseph James, Martin E. Straumanis

Chemistry Faculty Research & Creative Works

No abstract provided.

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Stored Energy Of Room Temperature Deformed Copper, G. J. Filatovs, Hollis P. Leighly Jan 1971

Stored Energy Of Room Temperature Deformed Copper, G. J. Filatovs, Hollis P. Leighly

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Activation Volumes Of Interstitial Diffusion In Ferromagnetic Metals And Alloys, Manfred Wuttig, J. Keiser Jan 1971

Activation Volumes Of Interstitial Diffusion In Ferromagnetic Metals And Alloys, Manfred Wuttig, J. Keiser

Materials Science and Engineering Faculty Research & Creative Works

The Dis accommodation technique was used to determine the activation volumes of carbon diffusion ΔV of a Fe-1.4 wt% Si alloy, of hcp cobalt, and of nickel at the temperatures of -21, 75, and 110°C, respectively. The obtained values of ΔV are +0.3 ± 0.3 and -0.6 ± 0.9 cm3 mole-1 for the two relaxations observed in hcp cobalt, and 1.2 ± 0.1 cm3 mole-1 for nickel. These results are discussed in terms of a continuum model that interprets the activation energy of diffusion as a sum of the strain and exchange energies. It is found that in ferromagnetic solids …

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On The Activation Entropy Of Interstitial Diffusion In B.C.C. Iron, Manfred Wuttig Jan 1971

On The Activation Entropy Of Interstitial Diffusion In B.C.C. Iron, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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An Age Hardening Study Of Magnesium-Thorium-Manganese Alloys, Kuldip Singh Chopra Jan 1971

An Age Hardening Study Of Magnesium-Thorium-Manganese Alloys, Kuldip Singh Chopra

Doctoral Dissertations

"The age hardening processes in Mg-3.5 wt.% Th-1.0 wt.% Mn and Mg-1.0 wt.% Th-1.0 wt.% Mn alloys have been studied by light and electron microscopy, and by electron and X-ray diffraction. At aging temperatures of 300ºC and below, G.P. zone formation rapidly hardens these alloys followed by the precipitation of disc shaped plates during averaging. During aging above 300ºC, no G.P. zones form and the disc shaped precipitate grows to very large sizes. The combined results of X-ray and electron diffraction indicate that the disc shaped precipitate has a Mg₃Cd (DO₁₉) type structure. The basal plane of the Mg₃Th discs …

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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 …

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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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