Metallurgy Commons^™

An Equilibrium Study Of The System Bi-S-H₂, Don Hie Lee

Masters Theses

"An experimental study has been conducted to determine the equilibrium behavior of the system Bi-S-H₂. The system was studied by equilibrating H₂-H₂S gas mixtures with Bi(l)- Bi₂S₃(s) two-phase mixtures at temperatures of 500°, 600°, 700° and 750°C in a circulating type equilibrium apparatus. The equilibrium gas mixtures were analyzed by a Fisher Gas Partitioner with a reproducibility of approximately 0.06 %.

A linear free energy equation has been derived from the results with an average deviation of ± 1 Kcal. This deviation is well within the accepted experimental accuracy for …

Determination Of The Standard Free Energy Of Formation Of Zr₃S₂, Peter E. Otten

Masters Theses

"The Knudsen effusion method was used to find the equilibrium magnesium pressure for the reaction

3 Zr (s) + 2 MgS (s) = 'Zr₃S₂' (s) + 2 Mg (v)

By using known standard free energy data for the formation of magnesium sulfide and by using the equilibrium magnesium pressure, the standard free energy of formation of Zr₃S₂ was calculated and could be expressed by the equation

Δ F° = -139,800 + 49.13 T cal/mole

in the temperature range 900 to 1100°C.

It was also found that Zr₃S₂ was the zirconium …

A Thermodynamic Study Of The Molybdenum-Sulfur System At 1100⁰C, Seth C. Schaefer

Masters Theses

"A static method was used to determine equilibrium sulfur pressure for molybdenum-sulfur mixtures at 1100°C.

The results obtained were:
(1) The molybdenum disulfide phase was stable in a sulfur pressure range of 1.023 x 10^-5 to 6.026 x 10^-1 atmospheres. A range of non-stoichiometry from MoS_2.00 to MoS_2.22 was determined under these conditions.
(2) The upper limit of sulfur content of molybdenum sesquisulfide (Mo₂S₃) is nearly stoichiometric.
(3) The extent of solid solution of sulfur in molybdenum is approximately 1.5 atomic % (0.5 wt %).
(4) Molybdenum sesqu-isulfide (Mo₂S_{3 …}

A Study Of The Solubility Of Gold In Aluminum And The Extent Of The Al₂Au Phase., Kuldip Singh Chopra

Masters Theses

"The lattice constant of pure aluminum (99.998%) at 25° C 0 was determined to be 4.04953 A and the limit of solubility of gold in aluminum at 58O° c was found to be about o.4 weight percent gold. The minimum of the lattice constant was observed at O.75 weight percent gold. No change in the lattice constant with time was found.

The Al₂Au phase has a range from 77.66 to 78.94 weight percent gold with the theoretical composition of Al₂Au nearly in the middle of the phase. The thermal coefficient of expansion, the density and the …

An Electrolytic Polishing And Recrystallization Study Of Zinc And Zinc Alloys., Roy Ashley Smith

Masters Theses

"A Unitron hot stage and polarized light were used to enable direct observation of recrystallization in high purity (99.99 per cent) zinc and high zinc content alloys. Electrolytic polishing was investigated in an attempt to prepare unetched surfaces which would show good structural contrast under polarized light and thus permit structural changes occurring during recrystallization to be observed.

Kinetic data obtained from a sequence of photographs during each recrystallization trial showed typical sigmoidal isothermal reaction curves characteristic of a nucleation and growth process. It was determined that rates of nucleation and grain growth are a maximum over the same time …

A Study Of The Relative Electric Resistance Of Commercial Steels And Pure Iron, William Eugene Wistehuff

Masters Theses

"The change in relative electric resistance of five commercial steels, Armco Ingot Iron and Pure Iron were studied over the temperature range of 800°C to 1100°C in an attempt to correlate the phenomena of hot or red shortness with a change in the Electric resistance .

The results from the above resistance measurements were compared with mechanical tests of the same steels to show that at the point at which the iron sulfide liquid forms there is a definite change in the slope of the electric resistance vs temperature curve.

Also studied was a discontinuity in the electric resistance vs …

A Dilatometric Study Of The Martensite Transformation And Maraging Behavior Of A Ni- Co- Mo Steel, Neal Matthias Griesenauer

Masters Theses

"An experimental investigation or the austenite to martensite transformation and the maraging behavior taking place in a nickel-cobalt-molybdenum steel was conducted for this project.

The austenite to martensite transformation was followed by the dilatometric method, being done on a Leitz Optical Dilatometer. An apparatus was constructed for the dilatometer in order to record dimensional changes at low temperatures, thus broadening the possible applications for the instrument.

The maraging behavior was investigated by means of metallographic analysis and hardness determinations"--Abstract, page i.

A New Method Of Making Stainless Steel Powder By Electrochemical Disintegration, Mohammed Maher Saad

Masters Theses

"This paper describes a new method of making austenitic stainless steel (18/8) powder by electrochemical disintegration. The method used an external direct current applied to a heat-treated stainless steel anode, and a platinum cathode in an electrolyte of an aqueous solution of 20% HNO₃ and 1% H₂SO₄ by weight respectively.

Special attention has been paid to the size distribution of sieve and sub-sieve sizes, and the following ranges were found: approximately one-half lies between the limits of 200 and 325 mesh, and one third is finer than 325 mesh, with the remainder about +200 mesh, average …

Electrodeposition Of Antimony From Sulfide Melts, Mahendra N. Rana

Masters Theses

"A study of the current-potential relationships, and the electrodeposition of antimony metal was conducted for fused mixtures of Sb₂S₃-Na₂S, Sb₂S₃-Sb and Sb₂S₃-NaCl-KCl in the temperature range of 700° - 900°C. An attempt was made to determine the mutual solubility of molten antimony and Sb₂S₃-Na₂S melts. The microstructure of deposited metal was studied metallographically. Analysis of phases present in the matte mixture (Sb₂S₃-Na₂S) was made by x-ray diffraction patterns.

All investigations were carried out in …

A Study Of The Recrystallization And Polygonization Of High Purity Aluminum, Robert Leon Wright

Masters Theses

"Laue back reflection patterns were used along with visual examination in evaluating the characteristics of the annealed structure of high purity (99.99%) aluminum single crystals which had been deformed by elongation. It was found that the glide strain and annealing temperature are primary factors to be considered with respect to the structural changes occurring during annealing.

It was determined that the glide strain must be above a certain critical value to cause recrystallization; below the critical value polygonization will predominate in the annealed structure regardless of the annealing temperature.

The single crystals used in the investigation were grown by the …

A Study Of Segregation In Cast Aluminum-Uranium Alloys, B. L. Bramfitt

Masters Theses

"This investigation involves a photomicrographic study of the segregation resulting from the eutectic solidification characteristics of aluminum-uranium alloys, ranging from 5 to 30 weight percent uranium. The segregation can occur in either of two manners; the first, due to the gravitational forces acting upon the growing particles which nucleate in the melt and the second, due to the mode and rate of heat transfer through the material. It was found that segregation occurred only as the result of the latter factor due to the small volume of the ingot and the rapid rate of heat transfer. The segregation was measured …

A Determination Of Vapor Pressure Of Barium In The Thermal Production Of Barium Metal, Thomas A. Theobald

Masters Theses

The Knudsen effusion method was used to find the equilibrium reaction pressure of barium for the following reactions:
4BaO + 2Al - 3Ba + BaO·Al₂O₃ (l)
4BaO + Si - 2Ba + 2BaO·SiO₂ (2).
The resulting barium pressure for reaction (l) ranged from 0.27 mm. Hg to 1.77 mm. Hg in a temperature range of 940°C to 1086°C. The barium pressures for reaction (2) varied from 0.38 mm. Hg to 1.94 mm. Hg in a temperature range of 1000°C to 1086°C. The free energies of formation of BaO·Al₂O₃ and 2BaO·SiO₂ at 1087°C …

A Survey Of The Influence Of Selected Sulfides On The Thermal Decomposition Rate Of Zinc Sulfate, L. G. Twidwell

Masters Theses

"The influence which ZnS, CdS, Cu₂S, PbS, and FeS has on the thermal decomposition rate of ZnSO₄ was studied by measuring the SO₂ gas evolved per unit of time for various ZnSO₄-MeS mixtures at 600°C, and analyzing the solid phases by means of X-ray diffraction patterns.

The SO₂ gas evolved upon heating the pellets was analyzed as a function of time by absorbing the gas in a solution of distilled water, H₂O₂, and NaOH, and measuring the time required for the SO₂ to neutralize the NaOH. The gas …

A Study Of The Chemical Kinetics, Activation Energy And Difference Effect On Beryllium Dissolving In Mineral Acids, Daniel Santhamurthi Gnanamuthu

Masters Theses

"The rate of dissolution of polycrystalline beryllium was studied in hydrofluoric, hydrochloric and sulfuric acids. Two samples of beryllium containing different amounts of beryllium oxide were used. The experiments were performed at temperatures ranging from 20 to 50°C, and at various acid concentrations. The kinetics of these heterogeneous processes conformed to a reaction order of approximately one in all the cases. Since the conditions of the surface were complex during dissolution, these might complicate the reaction. This might be due to the oxide layer, which is present as impurity.

The difference effect was determined at various acid concentrations at 25°C …

A Study Of Several Commercial Steels In The Red Short Range, Jorge Alberto Espana

Masters Theses

"The red short phenomenon present in steel, was studied by means of torsion tests at temperatures between 800 and 1200⁰C. Cold drawn bars of different compositions of steels were tested, and the number of turns to failure and maximum twisting torque were plotted versus temperature.

All the steels tested, exhibited to have a certain degree of red shortness. By comparing the curves and the respective chemical analyses, the detrimental effect of sulphur and lead and the beneficial effect of manganese, was established.

Microscopic examinations revealed the intergranular nature of the cracks in the red short range. Sulphur and oxide distribution …

The Effect Of The Rolling Load On The Micro-Structure Of Low Carbon Sheet Steel, Jerry Lee Cadden

Masters Theses

"A Stanat 315, two high-four high, combination rolling mill is used to cold roll annealed, low carbon steel strips. A method of measuring the rolling load was presented. The method consisted of constructing a load cell using SR-4 strain gages attached to a steel column. The load cell was placed under the hold down screw of the rolling mill and a known load was applied. The stresses from this load were transferred to the mill housing where another SR-4 strain gage was located. The strain in the mill housing was recorded at the corresponding applied load. During rolling, the strain …

A Weight Loss Technique For The Determination Of Phase Boundaries, Robert Lee Benner

Masters Theses

"An apparatus has been designed and constructed that would continuously record the weight loss of a sample in a flowing inert atmosphere, at a constant temperature.

A technique has been developed to determine the phase boundaries of a binary phase diagram.

Alloys of the magnesium-nickel, cadmium-antimony, copper-cadmium, copper-zinc, and magnesium-zirconium systems were subjected to investigation to verify the operation and resolve a number of limitations of the equipment.

These investigations disclosed that the apparatus gave the best results with alloys having vapor pressures in the range between 1 and 35 millimeters of mercury"--Abstract, page 2.

An Investigation Of The Deformation Textures Of Cobalt, Roy Carl Wilcox

Doctoral Dissertations

"Deformation textures of various cobalt structures as a result of cold rolling together with some annealing textures were studied. The textures of cobalt were determined using a modification of the Schulz-Decker Geiger counter technique. Pole figures of the (1011), (0001) and (1010) planes were constructed. Also, a study of the microhardness of cobalt was made.

Microhardness tests were performed on various cobalt structures, in both the cold rolled and unworked conditions. The microhardness was found to vary with the source of the cobalt, the crystal orientation, and the amount of deformation and twinning. Deformation lines about the hardness impressions diffused …

Isothermal Decomposition Of Austenite (In 1.4% Tungsten Steel) At Subcritical Temperatures, Samir Moustafa Riad

Masters Theses

"An experimental investigation was conducted in order to study the relationship between temperature, time and the decomposition of austenite in Tungsten steel of a given composition - and to plot the T-T-T Diagram for this steel.

The steel was prepared, homogenized and cut into identical specimens for further heat treatment and metallographic inspection. Precautions were taken to prevent these specimens from decarburizing during any heat treatment.

This experimental work may be divided into three main parts:-

I. Determination of the critical temperature range; i.e. the range of temperature Ae₁ and Ae₃ above which austenite is stable and below …

Electron Microscope Study Of The Systems Cadmium-Cadmium Chloride And Lead-Lead Chloride, Dennis O'Neill

Masters Theses

"The nature of the dispersed phase in the cadmium-cadmium chloride and lead-lead, chloride systems were investigated with the electron microscope.

Preliminary experiments on preparing and examining the dispersed phase showed that it was most feasible to study the material by electron-microscopic examination of replicas made from the surfaces of the fractured materials. Melting apparatus and methods were chosen so that samples of the melts could be easily quenched to different temperatures and so that the samples could be easily fractured with a minimum of surface contamination. Of the conventional replicating techniques tried, that of carbon replicas pre-shadowed with chromium was …

A Study Of The Difference Effects On Alpha Solid Solutions Of Oxygen In Titanium Dissolving In Hydrofluoric Acid, Kuo-Chin Chuang

Masters Theses

"Alpha solid solutions of oxygen in titanium dissolving in hydrofluoric acid exhibited a positive difference effect with k values of 5.7, being independent of the concentration of HF, within the compositional range studied 0 to 5 w/o oxygen. This indicates that various TiO_x alloys are polarizable to the same extent by the same strength of anodic current in hydrofluoric acid.

The difference effect observed on TiO_x alloys dissolving in HF-HCl revealed that the effect is dependent on the oxygen content of the solid solution as well as on the concentration of HCl. The presence of HCl results in …

A Resistivity Study Of Hot Short Ferrous Alloys, Harold Alfred Koelling

Masters Theses

"Resistivity measurements were performed at elevated temperatures on four special ferrous alloys and one commercial iron. The alloys were pure iron, iron with .023 per cent sulfur, iron with .33 copper, iron with .32 copper and .024 sulfur. Other elements were held to the minimum amounts possible in order to determine the actual effects of sulfur and copper. The commercial alloy was Armco Iron.

Measurements of resistivity versus temperature were taken at slow heating rates to determine if the iron sulphide liquid film formed in the grain boundaries of red-short steels had any effect on the electrical resistivity"--Abstract, page 7.

A Preferred Orientation Study Of Sheet Formed By Rolling Copper, Nickel, Titanium And Tungsten Metal Powders, Martin Franklin Marchbanks

Masters Theses

"Pole figure scans of strip rolled from copper, nickel, titanium, and tungsten metal powders were made on samples taken across the width of the strip, and with various amounts of surface material removed, to determine if any preferred orientation existed. No preferred orientation was found in any of the samples examined.

The method used was a modification of the Schultz technique, using the Norelco Pole Figure Fixture, whose geometry and operation is described, in conjunction with the Norelco diffractometer.

Defocusing resulting during the run of a pole figure is discussed and a method for reducing this defocusing is described.

The …

The Effects Of Sulphur And Copper On Hot-Workability Of Pure Iron, Hung-Chi Chao

Masters Theses

"The independent effects of sulphur, copper and their combinations on the hot-workability of pure iron free from other elements was studied, with special emphasis on the red-short phenomenon. Electrolytic pure iron with the addition of 0.023 cent sulphur, 0.33 per cent copper and 0.024 per cent sulphur plus 0.032 per cent copper along with a heat of only electrolytic pure iron was melted under vacuum, and cast under helium pressure. The specimens machined from the forged bars were tested at various temperatures by the hot twist-test and by the constant energy single blow drop forging test to evaluate the hot-workability …

A Dissolution Rate Study Of Beryllium In Hydrofluoric Acid, Donald Lee Mathis

Masters Theses

"Beryllium was shown to react stoichiometrically with HF, HCl, and H₂SO₄ acids in accordance with a plus two valence. These reactions were investigated by the hydrogen evolution method.

Dissolution rates were determined in five concentrations, 0.01, 0.05, 0.10, 0.50, and 0,75 N, of HF acid at 10, 20, 30, 40 and 50°C, This was accomplished by the hydrogen evolution method and the results were based on the tested stoichiometry. Beryllium has a high dissolution rate in HF acid, which approximates the following under similar conditions: 10 times Al, 4 times Ti, and 1.5 times Zr. A kinetic …

High Temperature Oxidation Of Nickel, Virgil R. Friebel

Masters Theses

"Using a sensitive volumetric technique, a study was made of the kinetics of oxidation of nickel at 1200° C. and 1300° C. Three purities of nickel were used for the investigation which was limited to the initial three hours of reaction.

The rate of oxidation of nickel followed the parabolic rate law after an initial period of deviation which lasted up to 40 minutes. No direct correlation was found between the oxide thickness and the end of the period of deviation from the parabolic rate law.

The purity of the nickel was found to have a marked effect on the …

The Constitution Of Magnesium-Rich Magnesium-Zirconium Alloys, Kenneth Allen Fowler

Masters Theses

"The magnesium-zirconium system has been studied to 0.8 per cent zirconium which represents the limit of solubility of zirconium in liquid magnesium at 950°C. Alloys have been prepared by two methods of alloy additions, and the results compared. Microstructural studies have been made of the alloys in the cast, extruded, and heat-treated conditions. The limit of solid solubility has been determined on the basis of resistivity and temperature coefficient of resistivity measurements, as well as by metallographic examination, with good agreement. A secondary structure resulting from precipitation of a second phase within cored regions of the alloy has been studied …

The Effect Of The Rare Earth Elements On The Hot Workability Of Ingot Iron, L. A. Neumeier

Masters Theses

"The effect of mischmetal and rare earth oxides on the hot workability of ingot iron in the hot-short region was studied. Thirteen heats were melted in air in a basic-lined induction furnace. All heats were thoroughly deoxidized with aluminum prior to the rare earth additions. Mischmetal was added in amounts of 0.1, 0.3 and 0.5 per cent. Rare earth oxides were added in amounts of 0.1 and 0.2 per cent. Temperatures were maintained at approximately 2900°F and holding intervals between mischmetal additions and pouring at two minutes. Bars were hot rolled and swaged for hot twisting in the hot-short region. …

Segregation Method As Possible Process To Beneficiate Oxidized Lead Ores, Jose Molfino Tomasio

Masters Theses

"In this investigation it has been demonstrated that the Segregation Process has merit for treating oxidized lead ores.

The process comprises heating the crushed ore with salt and coal at about 750° C. to produce metallic lead attached to the carbon particles, which then is recovered by conventional flotation methods.

The quantities of sodium chloride and coal required for the best segregation of lead obtained in this work was 1.0 percent of coal and 1.0 percent of salt by weight.

Good segregation was obtained by using salt and coal as fine as 65 or 48 mesh. Segregation varied with the …

Imperfections In A Silicon Crystal Studied By The X-Ray And Density Method, Pierre Borgeaud

Masters Theses

"The study of imperfections in several crystals of silicon was conducted by the x-ray and density method"--Abstract, page 2.