Growth Kinetics of Intermetallic Phases in U-Mo vs. Al Alloy Diffusion Couples Annealed at 550°C

Perez, E.; Hotaling, Nathan; Ewh, Ashley; Keiser, Dennis D.; Sohn, Yong Ho

doi:10.4028/www.scientific.net/ddf.266.149

Cited by 16 publications

(17 citation statements)

References 8 publications

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“…During reactor operation, diffusion occurs producing intermetallic compounds with physical and thermal properties that cause adverse effects on the performance of the materials. [6,8] The reaction layer between the U-Mo and the Al matrix experiences significant volumetric expansion that causes fracturing. [9] Moreover, these compounds have lower thermal conductivities than desired, which results in heat buildup in the fuel particles that in turn accelerates the interdiffusion processes between the U-Mo and the Al alloys.…”

Section: Introductionmentioning

confidence: 99%

“…[9] Moreover, these compounds have lower thermal conductivities than desired, which results in heat buildup in the fuel particles that in turn accelerates the interdiffusion processes between the U-Mo and the Al alloys. [8,10] The growth and properties of the intermetallic compound layers that develop in the U-Mo/Al system must be controlled in order to improve the functionality and service life of the fuels.…”

Section: Introductionmentioning

confidence: 99%

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Microstructural Characterization of U-Nb-Zr, U-Mo-Nb, and U-Mo-Ti Alloys via Electron Microscopy

Ewh

Perez

Keiser

et al. 2010

J. Phase Equilib. Diffus.

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Ternary uranium molybdenum alloys are being examined for use as dispersion and monolithic nuclear fuels in research and test reactors. In this study, three such ternary alloys, with compositions U-10Nb-4Zr, U-8Mo-3Nb, and U-7Mo-3Ti in wt.%, were examined using scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM) with high angle annular dark field (HAADF) imaging via scanning transmission electron microscopy (STEM). These alloys were homogenized at 950°C for 96 h and were expected to be single-phase bcc-c-U. However, upon examination, it was determined that despite homogenization, each of the alloys contained a small volume fraction precipitate phase. Through SEM and XRD, it was confirmed that the matrix retained the bcc-c-U phase. TEM specimens were prepared using site-specific focused ion beam (FIB) in situ lift out (INLO) technique to include at least one precipitate from each alloy. By electron diffraction, the precipitate phases for the U-10Nb-4Zr, U-8Mo-3Nb, and U-7Mo-3Ti alloys were identified as bcc-(Nb,Zr), bcc-(Mo,Nb), and bcc-(Mo,Ti) solid solutions, respectively. The composition and phase information collected in this study was then used to construct ternary isotherms for each of these alloys at 950°C.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microstructural Characterization of U-Nb-Zr, U-Mo-Nb, and U-Mo-Ti Alloys via Electron Microscopy

Ewh

Perez

Keiser

et al. 2010

J. Phase Equilib. Diffus.

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“…Keiser et al, [22] Palancher et al, [25] and Perez et al [23,28] reported concentration profiles of sufficient thickness to permit analysis, by energy dispersive spectroscopy (EDS) and EPMA, of the interaction layer. Concentration profiles of U, Mo, and Al show negligible gradients with near constant concentrations, particularly for Al throughout the interdiffusion zone thickness.…”

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confidence: 98%

“…Perez et al [23] annealed a series of diffusion couples of U-Mo vs pure Al (99.999 pct) at 823 K (550°C), and determined the (U,Mo)Al 4 as the average composition of the interdiffusion zone based on electron probe microanalysis (EPMA). Mirandou et al, [24] Palancher et al, [25] and Mazaudier et al [26] observed, in addition to the (U,Mo)Al 3 and (U,Mo)Al 4 phases, the U 6 Mo 4 Al 43 and UMo 2 Al 20 ternary intermetallic phases, along with the cfi(a+d) decomposition of the U-Mo alloy.…”

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confidence: 99%

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

Perez

Keiser

Sohn

2011

Metall Mater Trans A

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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°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-UAl 3 , orthorhombic-UAl 4 , hexagonal-U 6 Mo 4 Al 43 , and cubicUMo 2 Al 20 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 U 6 Mo 4 Al 43 phase, which exhibits poor irradiation behavior that includes void formation and swelling.

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“…Diffusional interactions in the U-Mo-Al system have been extensively studied through diffusion-couple experiments [1][2][3][4][5][6][7][8], alloy casting and characterization [9,10], and characterization of U-Mo dispersions in Al matrix and monolithic plate assemblies encased in Al alloy [4,5,[11][12][13][14][15][16][17][18]. The studies have been carried out to support the Reduced Enrichment for Research and Test Reactors (RERTR) program [13] for the development of low-enriched U-Mo fuels encased in Al [13,[19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Results of U-xMo (x=7, 10, 12 wt.%) Alloy versus Al-6061 Cladding Diffusion Couple Experiments Performed at 500, 550 and 600 Degrees C

Perez¹,

Keiser²,

Sohn³

2013

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The Reduced Enrichment for Research and Test Reactors (RERTR) program has been developing low-enrichment fuel systems encased in Al-6061 for use in research and test reactors. U-Mo alloys in contact with Al and Al alloys can undergo diffusional interactions that can result in the development of interdiffusion zones with complex fine-grained microstructures composed of multiple phases. A monolithic fuel currently being developed by the RERTR program has local regions where the U-Mo fuel plate is in contact with the Al-6061 cladding and, as a result, the program finds information about interdiffusion zone development at high temperatures of interest. In this study, the microstructural development of diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo, and U-12wt.%Mo vs. Al-6061 (or 6061 aluminum) cladding, annealed at 500, 550, 600°C for 1, 5, 20, 24, or 132 hours, was analyzed by backscatter electron microscopy and x-ray energy dispersive spectroscopy on a scanning electron microscope. Concentration profiles were determined by standardized wavelength dispersive spectroscopy and standardless x-ray energy dispersive spectroscopy. The results of this work shows that the presence of surface layers at the U-Mo/Al-6061 interface can dramatically impact the overall interdiffusion behavior in terms of rate of interaction and uniformity of the developed interdiffusion zones. It further reveals that relatively uniform interaction layers with higher Si concentrations can develop in U-Mo/Al-6061 couples annealed at shorter times and that longer times at temperature result in the development of more non-uniform interaction layers with more areas that are enriched in Al. At longer annealing times and relatively high temperatures, UMo/Al-6061 couples can exhibit more interaction compared to U-Mo/pure Al couples. The minor alloying constituents in Al-6061 cladding can result in the development of many complex phases in the interaction layer of U-Mo/Al-6061 cladding couples, and some phases in the interdiffusion zones of U-Mo/Al-6061 cladding couples are likely similar to those observed for U-Mo/pure Al couples.

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Growth Kinetics of Intermetallic Phases in U-Mo vs. Al Alloy Diffusion Couples Annealed at 550°C

Cited by 16 publications

References 8 publications

Microstructural Characterization of U-Nb-Zr, U-Mo-Nb, and U-Mo-Ti Alloys via Electron Microscopy

Microstructural Characterization of U-Nb-Zr, U-Mo-Nb, and U-Mo-Ti Alloys via Electron Microscopy

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

Results of U-xMo (x=7, 10, 12 wt.%) Alloy versus Al-6061 Cladding Diffusion Couple Experiments Performed at 500, 550 and 600 Degrees C

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