A numerical description of nitrogen diffusion in titanium at elevated temperatures
department or school: Applied Science, Faculty of
department or school: Materials Engineering, Department of
data provider: DSpace
degree campus: UBCV
creator: Hawker, Daniel
issued: 2021-08-09T22:19:18Z
issued: 2021
related degree: Master of Applied Science - MASc
degree grantor: University of British Columbia
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 predic…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/79232
note: A NUMERICAL DESCRIPTION OF NITROGEN DIFFUSION IN TITANIUM AT ELEVATED TEMPERATURES by Daniel Hawker B.A., Dublin University, 2018 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Materials Engineering) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) July 2021 © Daniel Hawker, 2021 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the thesis entitled: A numerical description of nitrogen transport in titanium at elevated temperatures submitted by Daniel Hawker in partial fulfillment of the requirements for the degree of Master of Applied Science in Materials Engineering Examining Committee: Steven Cockcroft, Materials Engineering, UBC Supervisor David Dixon, Materials Engineering, UBC Supervisory Committee Member Daan Maijer, Materials Engineering, UBC Supervisory Committee Member iii 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 × …
has type: Thesis/Dissertation
date issued: 2021-11
is shown at: 10.14288/1.0401265
language: eng
degree discipline: Materials Engineering
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Cockcroft, Steve L.
type: Text
identifier URI: http://hdl.handle.net/2429/79232