The Library
Employing density functional theory to model the thermodynamic behaviour and diffusion of nitrogen in the iron-nitrogen-vacancy system
Tools
Karimi, Aurash (2021) Employing density functional theory to model the thermodynamic behaviour and diffusion of nitrogen in the iron-nitrogen-vacancy system. PhD thesis, University of Warwick.
|
PDF
WRAP_Theses_Karimi_2021.pdf - Submitted Version - Requires a PDF viewer. Download (8Mb) | Preview |
Official URL: http://webcat.warwick.ac.uk/record=b3763706
Abstract
This project adopts density functional theory (DFT) in a multiscale modelling approach to study thermodynamics and diffusion in the iron-nitrogen-vacancy system. This allows for more robust models of nitriding, which is a common heat treatment process used in the global steel industry. Current models for nitriding tend to depend heavily on empirical data, and while this is satisfactory for many purposes, it does not allow for effective modelling when the empirical data is not available or difficult to obtain experimentally. DFT calculations, although they require consider computational effort, are ideal for such scenarios. Through DFT, the formation of nitrogen-vacancy complexes are investigated in conditions that represent the nitriding process, both at thermodynamic equilibrium and metastable states where vacancies are in excess. The latter of which was found to be more reflective of real manufacturing conditions, under which the iron crystal structure is not uniform and defect-free. Further, this work quantifies the diffusion behaviour of nitrogen in vacancy-rich conditions. This has far-reaching implications, as precise models for diffusion are required to design the treatment so that a quality result is achieved. For instance, there should not be sharp changes in nitrogen content throughout the metal, or it loses a significant amount of load bearing ability.
Item Type: | Thesis (PhD) | ||||
---|---|---|---|---|---|
Subjects: | Q Science > QC Physics Q Science > QD Chemistry T Technology > TA Engineering (General). Civil engineering (General) T Technology > TN Mining engineering. Metallurgy T Technology > TS Manufactures |
||||
Library of Congress Subject Headings (LCSH): | Density functionals, Thermodynamics, Thermodynamic equilibrium, Solid state chemistry, Point defects, Phase transformations (Statistical physics) | ||||
Official Date: | January 2021 | ||||
Dates: |
|
||||
Institution: | University of Warwick | ||||
Theses Department: | Warwick Manufacturing Group | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Auinger, Michael | ||||
Format of File: | |||||
Extent: | xiii, 112 leaves : illustrations | ||||
Language: | eng |
Request changes or add full text files to a record
Repository staff actions (login required)
View Item |
Downloads
Downloads per month over past year