- Library Home /
- Search Collections /
- Open Collections /
- Browse Collections /
- UBC Theses and Dissertations /
- A numerical description of nitrogen diffusion in titanium...
Open Collections
UBC Theses and Dissertations
UBC Theses and Dissertations
A numerical description of nitrogen diffusion in titanium at elevated temperatures Hawker, Daniel
Abstract
As part of a program to understand the dissolution of nitrogen-rich titanium solids in liquid titanium, a numerical study of nitrogen diffusion in titanium at elevated temperatures has been carried out. A Landau transformation was applied to the equations governing nitrogen diffusion which were used as the basis for the numerical models developed in this study. To begin a numerical model describing the nitriding of commercially pure titanium was developed. The numerical model was used initially to simulate nitrogen diffusion in a planar geometry and the predicted nitrogen concentration profiles and displacement of Ti-N phase boundaries showed good agreement with analytically derived solutions. The numerical model was then used to simulate nitrogen transport in commercially pure titanium cylinders. The model results were shown to be sensitive to the diffusion coefficients of Ti-N phases present in the system. Based on a sensitivity analysis, diffusion coefficients at 1650 °C of 4.3×10⁻¹¹ m²·s⁻¹, 1.6×10⁻¹¹ m²·s⁻¹ and 1.7×10⁻¹² m²·s⁻¹ for β-Ti, α-Ti and TiN phases, respectively, were back calculated using the model. The model predictions, using the new diffusion coefficients, showed good agreement with previously published data in terms of both the nitrogen concentration profiles and displacements of Ti-N phase boundaries under the conditions examined in the study. The comparison indicates the model framework is capable of accurately approximating the diffusion of nitrogen in titanium at elevated temperatures. In work that followed, the model framework was used to develop an improved numerical model for describing the dissolution of Ti-N particles in liquid titanium. The results of the improved methodology have been compared to a second finite-difference based model formulated using the conventional approach for interface motion. The improved approach accurately accounts for conservation of nitrogen associated with interface motion and hence has the potential to predict particle dissolution times more accurately in commercial melt refining operations.
Item Metadata
Title |
A numerical description of nitrogen diffusion in titanium at elevated temperatures
|
Creator | |
Supervisor | |
Publisher |
University of British Columbia
|
Date Issued |
2021
|
Description |
As part of a program to understand the dissolution of nitrogen-rich titanium solids in liquid titanium, a numerical study of nitrogen diffusion in titanium at elevated temperatures has been carried out. A Landau transformation was applied to the equations governing nitrogen diffusion which were used as the basis for the numerical models developed in this study.
To begin a numerical model describing the nitriding of commercially pure titanium was developed. The numerical model was used initially to simulate nitrogen diffusion in a planar geometry and the predicted nitrogen concentration profiles and displacement of Ti-N phase boundaries showed good agreement with analytically derived solutions. The numerical model was then used to simulate nitrogen transport in commercially pure titanium cylinders. The model results were shown to be sensitive to the diffusion coefficients of Ti-N phases present in the system. Based on a sensitivity analysis, diffusion coefficients at 1650 °C of 4.3×10⁻¹¹ m²·s⁻¹, 1.6×10⁻¹¹ m²·s⁻¹ and 1.7×10⁻¹² m²·s⁻¹ for β-Ti, α-Ti and TiN phases, respectively, were back calculated using the model. The model predictions, using the new diffusion coefficients, showed good agreement with previously published data in terms of both the nitrogen concentration profiles and displacements of Ti-N phase boundaries under the conditions examined in the study. The comparison indicates the model framework is capable of accurately approximating the diffusion of nitrogen in titanium at elevated temperatures.
In work that followed, the model framework was used to develop an improved numerical model for describing the dissolution of Ti-N particles in liquid titanium. The results of the improved methodology have been compared to a second finite-difference based model formulated using the conventional approach for interface motion. The improved approach accurately accounts for conservation of nitrogen associated with interface motion and hence has the potential to predict particle dissolution times more accurately in commercial melt refining operations.
|
Genre | |
Type | |
Language |
eng
|
Date Available |
2021-08-09
|
Provider |
Vancouver : University of British Columbia Library
|
Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
|
DOI |
10.14288/1.0401265
|
URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
|
Graduation Date |
2021-11
|
Campus | |
Scholarly Level |
Graduate
|
Rights URI | |
Aggregated Source Repository |
DSpace
|
Item Media
Item Citations and Data
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International