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Title: First-principles study of solute diffusion mechanisms in alpha-Ti
Author: Scotti, Lucia
ISNI:       0000 0004 5994 6861
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2016
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Diffusion mechanisms govern a wide range of phenomena in condensed matter including high-temperature deformation. The good influence of slow diffusers such as Si on the creep properties of α-Ti alloys is well documented, as well as the detrimental effect of fast-diffusers such as Fe, Co and Ni. The life-performance of α-Ti alloys at high temperature is also limited by light elements (O, C and N) that promote the fragile α-case phase. The study of diffusion mechanism is experimentally not trivial, since the anisotropy hcp structure of α-Ti requiring single crystal sample. The first-principles approach together with analytical models and Kinetic Monte Carlo simulations can predict the diffusivity values giving additional information on mechanism itself. This work presents the ab initio study of vacancy-mediated diffusion of substitutional atoms as Si, Al, Ga, Ge, In and Sn, interstitial migration of light elements, and anomalous behavior of fast-diffusers. The findings show that the substitutional diffusion is affected by the bonding characteristic. The interstitial sites through which light elements dissolve and diffuse were updated, and they can explain the anisotropy behaviour of these solutes. The results confirm that the anomalous behaviour of fast-diffusers is a results of their ability to dissolve interstitially and substitutionally.
Supervisor: Not available Sponsor: University of Birmingham
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TN Mining engineering. Metallurgy