Degree Type

Dissertation

Date of Award

1980

Degree Name

Doctor of Philosophy

Department

Materials Science and Engineering

Abstract

The decay of periodic profile on the surfaces of single crystalline vanadium specimen is orientation dependent. Faceting occurs on both (100) and (110) surfaces. Periodic profile becomes sinusoidal on the (111) surface and the sinusoidal profile becomes distorted on a surface 9(DEGREES) away from the (111) plane. The surface self-diffusion coefficient of vanadium was determined by using Mullins' theory of sinusoidal profile decay on the (111) surface. The results are;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI);and;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI);The anisotropy indicates that the effect of ledges cannot be neglected. The experimental activation energy is lower than that calculated from the pairwise interaction model and the heat of sublimation. This difference is attributed to the fact that the model does not account for both the lattice relaxation and the electron redistribution at the surface. In general, the surface self-diffusion coefficients of bcc refractory metals can be expressed as;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI);This expression predicts the diffusion coefficients to within a factor of two or three.

DOI

https://doi.org/10.31274/rtd-180813-3586

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Jick Ming Yu

Language

en

Proquest ID

AAI8019678

File Format

application/pdf

File Size

105 pages

Included in

Metallurgy Commons

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