Table of Contents
Journal of Metallurgy
Volume 2011 (2011), Article ID 954170, 8 pages
http://dx.doi.org/10.1155/2011/954170
Research Article

Cohesive Relations for Surface Atoms in the Iron-Technetium Binary System

Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87544, USA

Received 6 June 2011; Accepted 8 August 2011

Academic Editor: Livio Battezzati

Copyright © 2011 Christopher D. Taylor. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Iron-technetium alloys are of relevance to the development of waste forms for disposition of radioactive technetium-99 obtained from spent nuclear fuel. Corrosion of candidate waste forms is a function of the local cohesive energy (Eloc) of surface atoms. A theoretical model for calculating Eloc is developed. Density functional theory was used to construct a modified embedded atom (MEAM) potential for iron-technetium. Materials properties determined for the iron-technetium system were in good agreement with the literature. To explore the relationship between local structure and corrosion, MEAM simulations were performed on representative iron-technetium alloys and intermetallics. Technetium-rich phases have lower Eloc, suggesting that these phases will be more noble than iron-rich ones. Quantitative estimates of Eloc based on numbers of nearest neighbors alone can lead to errors up to 0.5 eV. Consequently, atomistic corrosion simulations for alloy systems should utilize physics-based models that consider not only neighbor counts, but also local compositions and atomic arrangements.