Title

Interdiffusion, Intrinsic Diffusion, Atomic Mobility, and Vacancy Wind Effect in gamma(bcc) Uranium-Molybdenum Alloy

Authors

Authors

K. Huang; D. D. Keiser;Y. H. Sohn

Comments

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Abbreviated Journal Title

Metall. Mater. Trans. A-Phys. Metall. Mater. Sci.

Keywords

MO DISPERSION FUEL; EN PHASE-GAMMA; U-MO; DES COEFFICIENTS; HIGH-DENSITY; ETUDE; LAUTODIFFUSION; AL; MATRIX; Materials Science, Multidisciplinary; Metallurgy & Metallurgical; Engineering

Abstract

U-Mo alloys are being developed as low enrichment uranium fuels under the Reduced Enrichment for Research and Test Reactor (RERTR) Program. In order to understand the fundamental diffusion behavior of this system, solid-to-solid pure U vs Mo diffusion couples were assembled and annealed at 923 K, 973 K, 1073 K, 1173 K, and 1273 K (650 A degrees C, 700 A degrees C, 800 A degrees C, 900 A degrees C, and 1000 A degrees C) for various times. The interdiffusion microstructures and concentration profiles were examined via scanning electron microscopy and electron probe microanalysis, respectively. As the Mo concentration increased from 2 to 26 at. pct, the interdiffusion coefficient decreased, while the activation energy increased. A Kirkendall marker plane was clearly identified in each diffusion couple and utilized to determine intrinsic diffusion coefficients. Uranium intrinsically diffused 5-10 times faster than Mo. Molar excess Gibbs free energy of U-Mo alloy was applied to calculate the thermodynamic factor using ideal, regular, and subregular solution models. Based on the intrinsic diffusion coefficients and thermodynamic factors, Manning's formalism was used to calculate the tracer diffusion coefficients, atomic mobilities, and vacancy wind parameters of U and Mo at the marker composition. The tracer diffusion coefficients and atomic mobilities of U were about five times larger than those of Mo, and the vacancy wind effect increased the intrinsic flux of U by approximately 30 pct.

Journal Title

Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science

Volume

44A

Issue/Number

2

Publication Date

1-1-2013

Document Type

Article

Language

English

First Page

738

Last Page

746

WOS Identifier

WOS:000313718800016

ISSN

1073-5623

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