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https://hdl.handle.net/2142/68650
Description
Title
Oxygen Diffusion in Vanadium-Based Alloys
Author(s)
De Avillez, Roberto Ribeiro
Issue Date
1981
Department of Study
Metallurgy and Mining Engineering
Discipline
Metallurgical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Metallurgy
Language
eng
Abstract
The experimental study of transport and equilibrium properties of oxygen in vanadium-based alloys was made by EMF measurements on solid electrolytic cells over the temperature range of 873-1423(DEGREES)K. The oxygen diffusion in vanadium was not significantly modified by small additions of Ti, Cr, Ni, Nb and Ta. The increase in the activation energy for oxygen diffusion in the V-based alloys containing Cr, Ni, Nb and Ta probably reflects the effect of these substitutional solutes on the activity coefficient of oxygen. The oxygen activity was increased by the addition of 1 at% of Cr, Ni and Nb, and decreased by the addition of Ti and Ta. However, the effects in the alloys containing Nb and Ta are very small.
Approximate values for the first order elastic interaction energy between a substitutional solute and oxygen interstitial were computed and compared with the oxygen binding energies to substitutional solutes in niobium. These comparisons together with the present results for the vanadium system suggest that the main contribution to the interactions between substitutional-interstitial solutes arises from chemical effects.
The EMF technique was shown capable of monitoring the kinetics of a precipitation process. The oxygen precipitation in vanadium alloys containing Ti, Zr and Hf certainly suggests attractive interactions between oxygen and these solutes.
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