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Articles 421 - 450 of 743

Full-Text Articles in Metallurgy

Cathodic Behavior Of Co, Co-Fe Alloys And Some Other Metals In Acids In A Cathodic Protection Arrangement, Ram Bajaj Jan 1970

Cathodic Behavior Of Co, Co-Fe Alloys And Some Other Metals In Acids In A Cathodic Protection Arrangement, Ram Bajaj

Masters Theses

"During cathodic protection of a corroding metal, electrons are forced into the metal by a sacrificial anode, a battery or a rectifier. These electrons, which constitute the suppressing or external current, are discharged (by H⁺ of the corrosive liquid) on the local cathode of the corroding metal decreasing the emf of the local cells, and, thus, reducing the cell current or the rate of corrosion of the metal. This process was studied in detail by finding out the relationship existing between the cell and suppressing currents. The study was made using two circuits: the cell circuit (representing the local current) …


Exact Solution For A Model Of Dislocation Pipe Diffusion, J. Mimkes, Manfred Wuttig Jan 1970

Exact Solution For A Model Of Dislocation Pipe Diffusion, J. Mimkes, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

The dislocations are treated as an ideal array of parallel pipes of radius and diffusivity Dp embedded in the bulk material of the diffusivity Db. The exact solution of this problem of diffusion along semi-infinite edge dislocations is presented for cubic, tetragonal, and hexagonal crystals. The solution makes it possible to evaluate the dislocation pipe radius a and the ratio of diffusivities from one experiment. It is applied to experimental data for self-diffusion in tellurium available in the literature. The results of the calculations are a dislocation pipe radius a=(1.5 0.5)x10-4 cm and an activation energy for the pipe diffusion …


Electrode Reactions In Zinc Electrolysis, Ernest R. Cole Jan 1970

Electrode Reactions In Zinc Electrolysis, Ernest R. Cole

Doctoral Dissertations

"The effects of temperatures from 0°C to 50°C and current densities from 10 asf to 200 asf on the current efficiency in the electrolysis of pure zinc sulfate solutions (65 gpl Zn⁺⁺ - 200 gpl H₂SO₄) were determined. Pure platinum and platinum coated titanium anodes were used with an aluminum cathode. Platinum anodes were not inert at certain combinations of temperature and current density, and platinum acted as a low overvoltage impurity causing resolution of the cathode deposit. Orientation of the zinc deposits was found to vary with temperature and to have a distinct relationship to current efficiency. Preconditioning of …


The Oxidation Kinetics Of Liquid Lead And Lead Alloys, Thomas Edward Weyand Jan 1970

The Oxidation Kinetics Of Liquid Lead And Lead Alloys, Thomas Edward Weyand

Doctoral Dissertations

"Liquid lead and lead-silver alloys were investigated to determine the rates and products of oxidation in pure oxygen at temperatures of 350 to 600°C. The kinetic data were determined using a Cahn electro-balance. Liquid lead was found to follow a cubic rate of oxidation between 350 and 400°C. A parabolic rate was found at temperatures above 400°C. 0.496% silver and 2.258% silver alloys followed a cubic rate of oxidation from 350 to 550°C and tended to approach a parabolic rate of oxidation above this temperature. Silver additions were found to increase the rate of oxidation as compared to the pure …


Voids In Neutron Irradiated Aluminum, Nicholas H. Packan Jan 1970

Voids In Neutron Irradiated Aluminum, Nicholas H. Packan

Doctoral Dissertations

"Void formation in high purity aluminum resulting from irradiation to fluences between 1.5 x 10¹⁹ and 1.6 x 10²² neutrons/cm² (E > 0 .1 MeV) at a temperature of 55 ± 5ºC was studied, primarily by means of transmission electron microscopy. In particular the effects of neutron fluence and flux were examined, as well as the possible influences of both preexisting and transmutation-produced impurities. A very low concentration of voids (about 10¹²/cm³) resulted from irradiation to 1.5 x 10¹⁹ neutrons/cm²; they averaged about 150 Å in diameter. Void concentrations and sizes increased with fluence, reaching values of 6 x 10¹⁴ voids/cm³ …


The Deformation Mechanisms In Sublimed Magnesium Under Cyclic Loading, Babu Narian Thakur Jan 1970

The Deformation Mechanisms In Sublimed Magnesium Under Cyclic Loading, Babu Narian Thakur

Doctoral Dissertations

"A detailed study of the deformation processes in sublimed magnesium under reverse bending fatigue in air at room temperature has been undertaken utilizing the light, scanning and transmission electron microscopy. The Principal deformation modes are the basal slip and {10Ī2} twinning. The proportion of twinning increases markedly with the increasing stress level and the number of cycles. The evidence for cross slip is seen on the basal slip bands. The extrusions are seen not only along the basal slip lines but also along the {10Ī2} twin boundaries. In the later stages of fatigue, the extrusions chip off producing a notch …


Cation Grain-Boundary Diffusion In Sodium Chloride, K. R. Riggs, Manfred Wuttig Dec 1969

Cation Grain-Boundary Diffusion In Sodium Chloride, K. R. Riggs, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.


Thermal-Fatigue Of Type 304 Stainless Steel, Gajinder Bir Singh Arora Jan 1969

Thermal-Fatigue Of Type 304 Stainless Steel, Gajinder Bir Singh Arora

Masters Theses

"Thermal fatigue resistance of unrestrained samples of type 304 stainless steel has been investigated under different test conditions. The following studies are reported: (a) effects of heating and cooling rates on the initiation of cracks, (b) effects of upper and lower cycle temperatures on the initiation of cracks, (c) effect of water quenching and (d) the manner in which cracks initiated and propagated. It is shown that under cyclic conditions involving maximum temperatures up to 1000°C, the thermal fatigue life of the material decreases rapidly with rise in the maximum temperature of the cycle. The increase in the lower cycle …


Diffusion Of Iron And Cobalt In Nickel Single Crystals, Charles Frederick Heuer Jan 1969

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

Doctoral Dissertations

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


Isotope Effect Of Carbon Diffusion In An Fe-Si Alloy, Manfred Wuttig, E. T. Yen Jan 1969

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

Materials Science and Engineering Faculty Research & Creative Works

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


The Effect Of Thermal-Mechanical Processing Of The Exfoliation Corrosion Resistance Of An Aluminum-Zinc-Magnesium-Copper Alloy, James Lawrence Spehr Jan 1969

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

Masters Theses

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


Effect Of Hydrostatic Pressure On Anelastic Stress Relaxation In A Mixed-Alkali Silicate Glass, Young-Gil (Gilbert Y.) Kim Jan 1969

Effect Of Hydrostatic Pressure On Anelastic Stress Relaxation In A Mixed-Alkali Silicate Glass, Young-Gil (Gilbert Y.) Kim

Masters Theses

"The effect of hydrostatic pressure on the anelastic stress relaxation of a mixed-alkali silicate glass (0.05 Na₂O, 0.95 K₂O, 3 SiO₂) was studied at 75°C between ambient pressure and 6 kbar. The activation volume of diffusion was found to be - 4.2 cm³/mole. It is proposed that a reequilibration of the defect population at pressure gives rise to the negative activation volume of diffusion"--Abstract, page ii.


Anodic Oxidation Of Pure And D.S. (Dispersion Hardened) Lead In Sulfuric Acid Solutions, Rafael San Martin Aldazabal Jan 1969

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

Masters Theses

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


Precipitation Hardening Of A Mg - 3.5 Wt. % Th - 1. Wt. % Mn Alloy, Adolf Chun-Chiung Huang Jan 1969

Precipitation Hardening Of A Mg - 3.5 Wt. % Th - 1. Wt. % Mn Alloy, Adolf Chun-Chiung Huang

Masters Theses

"The precipitation process in a Mg - 3.5 wt. % Th - 1. wt. % Mn alloy during aging at 260⁰, 350⁰ and 400⁰C was determined principally by transmission electron microscopy. At 350⁰ and 400⁰C, general precipitation of the equilibrium Mg₄Th phase moderately hardens the alloy. No transition lattice of this phase was seen. The Mg₄Th precipitate forms initially as disc shaped plates parallel either to the prism or basal plane of the matrix...During prolonged aging at 400⁰C the plates lengthen into long laths on either of the above planes in the close packed direction...At 260⁰C an unidentified G. P. …


Establishment Of A Torsion Pendulum And Its Evaluation, Ashwin Kantilal Ghatalia Jan 1969

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

Masters Theses

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


Thermal Fatigue Testing Of Die Casting Die Steels, Kulwant Singh Sabharwal Jan 1969

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

Masters Theses

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


The Effect Of Aging On The Exfoliation Corrosion Characteristics Of 7178 Aluminum Alloy, J. James Slavick Jan 1969

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

Masters Theses

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


The Effect Of Small Additions Of Niobium Upon The Corrosion Rates And Electrochemical Potentials Of Iron In Hcl, Hf, And H₂So₄, Richard Lee Jones Jan 1969

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

Masters Theses

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


A Continuous Method For Determination Of The Evaporation Rate Of Zinc, Paul Alan O'Neill Jan 1969

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

Masters Theses

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


The Electrodeposition Of Zinc; Changes In Current Efficiency And Surface Structure Resulting From Various Addition Agents, Haruhisa Fukubayashi Jan 1969

The Electrodeposition Of Zinc; Changes In Current Efficiency And Surface Structure Resulting From Various Addition Agents, Haruhisa Fukubayashi

Masters Theses

"An examination of the surface structure of zinc electrodeposited from an acid-sulfate solution was made by scanning electron microscopy techniques. The current efficiencies were also determined, to a lesser extent, in order to correlate the results with the surface structures. Commercial and pure zinc oxide were used to prepare the neutral zinc sulfate solutions. The starting solutions were in a range of acid and zinc concentrations commonly used in commercial practice. Changes in morphology resulting from addition agents such as animal glue, gum arabic, and sodium silicate are compared"--Abstract, page ii.


Additional Magnetic Disaccommodations In Ternary Iron Base Alloys, R. H. Graham, Manfred Wuttig Jan 1969

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

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.


On The Influence Of Surface Roughness On The Determination Of Diffusion Constants, Manfred Wuttig Jan 1969

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

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.


Phase Equilibria And Thermodynamic Studies In The System Ca0-Fe0-Fe₂0₃₋Si0₂, Muharrem Timucin Jan 1969

Phase Equilibria And Thermodynamic Studies In The System Ca0-Fe0-Fe₂0₃₋Si0₂, Muharrem Timucin

Doctoral Dissertations

"A study of phase relations and thermodynamic properties of phases in the system CaO-FeO-Fe₂O₃-SiO₂ was conducted at 1450°C and 1550°C. The region of stability of the different phases was determined by microscopic examination of the specimens. The thermodynamic properties of liquid were determined by analyses of quenched samples equilibrated at oxygen pressures from about 10⁻¹¹ to 1 atm. Isothermal phase diagrams were constructed from data for 0, 5, 10, 20, and 30 weight percent silica sections of the CaO-FeO-Fe₂O₃-SiO₂ system, and the effect of temperature and increased silica additions on the oxygen solubility of the liquid oxides was measured. Multicomponent …


X-Ray Determination Of Lattice Parameters And Thermal Expansion Coefficients Of Aluminum, Silver And Molybdenum At Cryogenic Temperatures, Claude Lowell Woodard Jan 1969

X-Ray Determination Of Lattice Parameters And Thermal Expansion Coefficients Of Aluminum, Silver And Molybdenum At Cryogenic Temperatures, Claude Lowell Woodard

Doctoral Dissertations

"A multiple exposure back reflection diffraction camera was designed to mount on the vacuum jacket of a pressurized helium gas "Cryomite". With this design it is possible to obtain six diffraction exposures on a single film at any temperature in the range of 180 to 25°K. temperatures within this range are reached in short intervals and exposure periods are less than 30 minutes in a 2.875 inch (73.03 mm) diameter camera. Some of the advantages of this design are; direct measurements, multiple exposures on a single film, short exposures, direct compensation of film length changes due to evacuation or processing …


Grain Boundary Self-Diffusion In Sodium Chloride, Kenneth Ray Riggs Jan 1969

Grain Boundary Self-Diffusion In Sodium Chloride, Kenneth Ray Riggs

Doctoral Dissertations

"The diffusion of ²²sodium and ³⁶chlorine along tilt and twist grain boundaries in pure and calcium chloride doped sodium chloride bicrystals was investigated. No enhanced diffusion of ²²sodium along the grain boundaries was observed. Between 400°C and 500°C the chlorine grain boundary diffusion parameter, D'Δ, is described by D'Δ = (D'Δ)₀exp (-Qb/kT), where (D'Δ)₀ is approximately 10⁻⁷ cm³/sec and Qb is 1.15 ± .30 eV. The grain boundary angle, the grain boundary character (tilt or twist), and the calcium chloride concentration appear to have no pronounced effect upon the observed chlorine grain boundary diffusion. The ionic movement …


Calorimetry Of Room Temperature Deformed Copper, George Juri Filatovs Jan 1969

Calorimetry Of Room Temperature Deformed Copper, George Juri Filatovs

Doctoral Dissertations

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


The Iron-Holmium Binary System And Related Magnetic Properties, Gerald J. Roe Jan 1969

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

Doctoral Dissertations

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


Isotope Effect Of Interstitial Diffusion Of Carbon In A Dilute Fe-Si Alloy, Edward T. Yen Jan 1968

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

Masters Theses

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


Zener Disaccommodation In Dilute F.C.C. Co-Ti Alloys, H. B. Aaron, M. (Manfred) Wuttig, H. K. Birnbaum Jan 1968

Zener Disaccommodation In Dilute F.C.C. Co-Ti Alloys, H. B. Aaron, M. (Manfred) Wuttig, H. K. Birnbaum

Materials Science and Engineering Faculty Research & Creative Works

The magnetic Dis accommodation, i.e., the time dependence of the low field magnetic permeability, was investigated in cobalt base alloys containing 0-5.1 at.% (0-4.2 wt.%) titanium in the temperature range 400-700°C. A strong temperature dependence of the Dis accommodation observed in the range 430-530°C could be accounted for predominantly by a single first order relaxation process. Analyzing the data in terms of (a) a single exponential relaxation, (b) a lognormal distribution of relaxation times, and (c) a sum of exponential relaxations, it was shown that the relaxation strength varies as the square of the titanium concentration and that the relaxation …


Influence Of Continuous Precipitation Upon The Growth Kinetics Of The Cellular Reaction In An Al-Ag Alloy, H. I. Aaronson, J. B. Clark Jan 1968

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

Materials Science and Engineering Faculty Research & Creative Works

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