Title

Phase Constituents and Microstructure of Interaction Layer Formed in U-Mo Alloys vs Al Diffusion Couples Annealed at 873 K (600 A degrees C)

Authors

Authors

E. Perez; D. D. Keiser;Y. H. Sohn

Comments

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Abbreviated Journal Title

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

Keywords

URANIUM-MOLYBDENUM ALLOYS; SOLID-STATE REACTIONS; NEUTRON-DIFFRACTION; EQUILIBRIUM DIAGRAM; PATTERN-FORMATION; GROWTH-KINETICS; DISPERSION; FUEL; GAMMA-PHASE; VS. AL; GD-LU; Materials Science, Multidisciplinary; Metallurgy & Metallurgical; Engineering

Abstract

U-Mo dispersion and monolithic fuels are being developed to fulfill the requirements for research reactors, under the Reduced Enrichment for Research and Test Reactors program. In dispersion fuels, particles of U-Mo alloys are embedded in the Al-alloy matrix, while in monolithic fuels, U-Mo monoliths are roll bonded to the Al-alloy matrix. In this study, interdiffusion and microstructural development in the solid-to-solid diffusion couples, namely, U-15.7 at. pct Mo (7 wt pct Mo) vs pure Al, U-21.6 at. pct Mo (10 wt pct Mo) vs pure Al, and U-25.3 at. pct Mo (12 wt pct Mo) vs pure Al, annealed at 873 K (600 A degrees C) for 24 hours, were examined in detail. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron probe microanalysis (EPMA) were employed to examine the development of a very fine multiphase interaction layer with an approximately constant average composition of 80 at. pct Al. Extensive TEM was carried out to identify the constituent phases across the interaction layer based on selected area electron diffraction and convergent beam electron diffraction (CBED). The cubic-UAl3, orthorhombic-UAl4, hexagonal-U6Mo4Al43, and cubic-UMo2Al20 phases were identified within the interaction layer that included two- and three-phase layers. Residual stress from large differences in molar volume, evidenced by vertical cracks within the interaction layer, high Al mobility, Mo supersaturation, and partitioning toward equilibrium in the interdiffusion zone were employed to describe the complex microstructure and phase constituents observed. A mechanism by compositional modification of the Al alloy is explored to mitigate the development of the U6Mo4Al43 phase, which exhibits poor irradiation behavior that includes void formation and swelling.

Journal Title

Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science

Volume

42A

Issue/Number

10

Publication Date

1-1-2011

Document Type

Article

Language

English

First Page

3071

Last Page

3083

WOS Identifier

WOS:000293969900016

ISSN

1073-5623

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