Thesis (Ph. D.)--Lehigh University, 1999. / Includes vita. Bibliography: leaves 144-149.

The thermodynamic properties of the components in the Cu-Ni-S ternary system have been measured by means of the H₂S/H₂ ratio in a gas phase equilibrated with the molten matte at 1200°C. The measured sulphur potentials were integrated to establish the activities in the Cu₂S-Ni₃S₂ pseudobinary and the isoactivity lines over the ternary system. The resultant activity pattern suggests the presence of a pseudocomponent at approximately the composition 0.02 N Ni, 0.63 NCu, and 0.35 NS . The influence exerted by the pseudocomponent causes the activity of Cu₂S to be nearly constant in the miscibility gap. In this same region the activity of Ni₃S₂ is restricted to low values. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

No description available.

No description available.

The internal oxidation behaviour of Ni-base and Fe-base alloys containing approximately 5 at% Al and both with and without low concentration Cr additions in flowing low-oxygen atmospheres at 1273 K was studied. There were two groups of Febase alloys; ferritic alloys that were Fe-Al-Cr and others that also contained approximately 9.3 at% Ni in order to make them austenitic. Ni?base alloys were oxidised in oxygen partial pressures of either 4.6 ?? 10-11 atm or 9.8 ?? 10-13 atm and Febase alloys were oxidised in an oxygen partial pressure of 1.2 ?? 10-16 atm The aim of this investigation was to examine the effect of internal oxidation on Fe- and Ni-base alloys containing Al or Al with Cr. The morphology of the precipitates formed and rates of reaction were of interest. Oxidation of the ferritic Fe-base alloys produced internal oxidation only at lower solute concentrations. In these alloys steady state diffusion-controlled precipitation was prevented from occurring due to the formation of an oxide barrier at the reaction front, and cracking off of the internal oxidation zone. In all of the austenitic alloys (Ni-base and y-Fe-base) internal oxidation was observed after all exposures. In y-Fe-base alloys and in Ni-base alloys oxidised at the higher oxygen partial pressure (4.6 ?? 10-11 atm) precipitation zones were found to widen according to parabolic kinetics, indicating diffusion control. In Ni-base alloys oxidised at 9.8 ?? 10-13 atm, precipitation zones were observed to widen according to parabolic kinetics up to 40.9 hours. However, the rate slowed for longer reaction times due to coalescence of precipitates at the reaction front. The rate of internal oxidation decreased with increasing Cr, and thus total solute, concentration. The parabolic rate constants measured for internal oxidation were higher than predicted by Wagner's theory of internal oxidation, which is consistent with observations in previous studies. Kinetics were accelerated by the presence of elongated precipitates, aligned approximately normal to the alloy surface. Chromium alloy additions led to precipitate coarsening, and at lower oxygen partial pressures, to loss of elongated morphology. The precipitates formed were found to be a mixture of M2O3 and AM2O4, where M represents either Al or Cr, and A represents either Fe or Ni. Both oxide forms were detected at all depths within the internal oxidation zone. However, Cr-containing oxides were limited to the part of the internal oxidation zone closer to the alloy surface, while Al-containing oxides were present at all depths. This is consistent with thermodynamic predictions.

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Jan. 21, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Chemical and Materials Engineering, University of Alberta. Includes bibliographical references.

Thesis (M.S. in M.S.E.)--School of Materials Science and Engineering, Georgia Institute of Technology, 2004. Directed by W. Steven Johnson. / Includes bibliographical references (leaves 141-148).

No description available.

The internal oxidation behaviour of Ni-base and Fe-base alloys containing approximately 5 at% Al and both with and without low concentration Cr additions in flowing low-oxygen atmospheres at 1273 K was studied. There were two groups of Febase alloys; ferritic alloys that were Fe-Al-Cr and others that also contained approximately 9.3 at% Ni in order to make them austenitic. Ni?base alloys were oxidised in oxygen partial pressures of either 4.6 ?? 10-11 atm or 9.8 ?? 10-13 atm and Febase alloys were oxidised in an oxygen partial pressure of 1.2 ?? 10-16 atm The aim of this investigation was to examine the effect of internal oxidation on Fe- and Ni-base alloys containing Al or Al with Cr. The morphology of the precipitates formed and rates of reaction were of interest. Oxidation of the ferritic Fe-base alloys produced internal oxidation only at lower solute concentrations. In these alloys steady state diffusion-controlled precipitation was prevented from occurring due to the formation of an oxide barrier at the reaction front, and cracking off of the internal oxidation zone. In all of the austenitic alloys (Ni-base and y-Fe-base) internal oxidation was observed after all exposures. In y-Fe-base alloys and in Ni-base alloys oxidised at the higher oxygen partial pressure (4.6 ?? 10-11 atm) precipitation zones were found to widen according to parabolic kinetics, indicating diffusion control. In Ni-base alloys oxidised at 9.8 ?? 10-13 atm, precipitation zones were observed to widen according to parabolic kinetics up to 40.9 hours. However, the rate slowed for longer reaction times due to coalescence of precipitates at the reaction front. The rate of internal oxidation decreased with increasing Cr, and thus total solute, concentration. The parabolic rate constants measured for internal oxidation were higher than predicted by Wagner's theory of internal oxidation, which is consistent with observations in previous studies. Kinetics were accelerated by the presence of elongated precipitates, aligned approximately normal to the alloy surface. Chromium alloy additions led to precipitate coarsening, and at lower oxygen partial pressures, to loss of elongated morphology. The precipitates formed were found to be a mixture of M2O3 and AM2O4, where M represents either Al or Cr, and A represents either Fe or Ni. Both oxide forms were detected at all depths within the internal oxidation zone. However, Cr-containing oxides were limited to the part of the internal oxidation zone closer to the alloy surface, while Al-containing oxides were present at all depths. This is consistent with thermodynamic predictions.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves 120-121).