Phase field modelling of nickel oxidation

Johnson, Michael (2022). Phase field modelling of nickel oxidation. University of Birmingham. Ph.D.

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Abstract

Reactions occur in metallurgy, developing a methodology for including these reactions into a simple diffusion scheme has been undertaken within this work with an aim to simulate the reactions occurring during oxide growth. The diffusion scheme developed by Larsson [1] was used as the foundation of the scheme. Initially, the growth of Fe3C in bcc phase was simulated; the produced precipitate growth matched that of DICTRA.
This technique was modified to simulate the growth of (Fe, Cr)3C in a bcc phase. Further work was conducted to determine the interface reactions between the metal, oxide and gas phases. This simulation was used to model the growth of nickel oxide; these simulations produced kp results that agreed with Haugsrud [2]. Simulations provided a range of values for unknowns within the model; the rate of oxygen converting from the gas phase and the rate at which metallic nickel becomes ionic. These were determined to be 10 and 100s-1 and 1 × 10−4 and 1 × 10−5 times metal diffusion in the bulk phase respectively. The equations describing the motion of metal and gas ions within an oxide were modified and written in a phase-field consistent manner. The currently available phase-field models are not designed in a manner that is appropriate for the inclusion of the numerical schemes for the interface reactions; therefore a modified set of phase-field equations are proposed. Phase-field simulations studied the growth of nickel oxide; these simulations require further work to develop the curvature influence between the oxide and gas-phase. The lack of a suitable interfacial curvature limits the simulations ability to grow an oxide into the gas phase

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):