Characterization of U-Mo Foils for AFIP-7

Ermi, Ruby M.; Schemer-Kohrn, Alan L.; Overman, Nicole; Henager, Charles H.; Burkes, Douglas E.; Senor, David J.

doi:10.2172/1069212

Cited by 9 publications

(9 citation statements)

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“…Upon polishing, the samples were carbon coated for scanning electron microscopy (SEM) analysis. The detailed technique used to prepare the samples for characterization can be found in a previous report [12]. Microstructural characterization was performed using an optical microscope as well as using a JEOL JSM-7600F SEM equipped with an Oxford Instruments X-Max 80 energy dispersive spectroscopy (EDS) detector.…”

Section: Microstructural Characterization and Phase Analysismentioning

confidence: 99%

Thermomechanical process optimization of U-10wt% Mo – Part 2: The effect of homogenization on the mechanical properties and microstructure

Joshi

Nyberg

Lavender

et al. 2015

Journal of Nuclear Materials

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Please cite this article as: ABSTRACTIn the first part of this series, it was determined that the as-cast U-10Mo had a dendritic microstructure with chemical inhomogeneity and underwent eutectoid transformation during hot compression testing. In the present (second) part of the work, the as-cast samples were heat treated at several temperatures and times to homogenize the Mo content. Like the previous ascast material, the "homogenized" materials were then tested under compression between 500 and 800°C. The as-cast samples and those treated at 800°C for 24 hours had grain sizes of 25-30 µm, whereas those treated at 1000°C for 16 hours had grain sizes around 250 µm before testing.Upon compression testing, it was determined that the heat treatment had effects on the mechanical properties and the precipitation of the lamellar phase at sub-eutectoid temperatures.

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Section: Microstructural Characterization and Phase Analysismentioning

confidence: 99%

Thermomechanical process optimization of U-10wt% Mo – Part 2: The effect of homogenization on the mechanical properties and microstructure

Joshi

Nyberg

Lavender

et al. 2015

Journal of Nuclear Materials

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“…After polishing, the samples were carbon coated for scanning electron microscopy (SEM) analysis. The detailed technique used to prepare the samples for characterization can be found in Edwards et al (2012). Microstructural characterization was performed using an optical microscope as well as using a JEOL JSM-7600F scanning electron microscope equipped with an Oxford Instruments X-Max 80 energy-dispersive x-ray spectroscopy (EDS) detector.…”

Section: Characterization Of Microstructurementioning

confidence: 99%

Influence of Homogenization on the Mechanical Properties and Microstructure of the U-10Mo Alloy

Nyberg

Joshi

Lavender

et al. 2014

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In Phase 1 of this study, the mechanical properties of as-cast, depleted uranium alloyed with 10 weight percent molybdenum alloy (U-10Mo) samples were evaluated by high temperature compression testing. Compression testing was conducted at three strain rates over a temperature range of 400 to 800°C. The results indicated that with increasing test temperature, the material flow stress decreases and the material becomes more sensitive to strain rate. In addition, above the eutectoid transformation temperature (~ 550°C), the drop in material flow stress is prominent and shows a strain-softening behavior, especially at lower strain rates. In the second part of this research, we studied the effect that homogenization heat treatment had on the high temperature mechanical properties and microstructure of the cast U-10Mo alloy. Various homogenization times and temperatures were studied ranging between 800 and 1000°C for 4 to 48 hours. Based on the microstructural response in this homogenization study, a heat treatment cycle of 800°C for 24 hours and another at 1000°C for 16 hours were selected as the times at temperature to achieve a fully homogenized sample. Samples from these conditions were then compression tested at a variety of temperatures ranging from 500 to 800°C. The microstructure of these samples were compared to the as-cast samples and to a baseline sample homogenized at 1000°C for 16 hours. The results indicate that below the eutectoid temperature (~ 550°C) all three samples showed strain hardening and followed similar trends. Above the eutectoid temperature, the yield strength of the material decreased linearly. For the as-cast sample and the sample homogenized at 800°C for 24 hours, the n-values were negative, whereas for the samples homogenized at 1000°C for 16 hours the material exhibited a perfectly plastic behavior. The as-cast sample, heat treated at 800°C for 24 hours, showed significant lamellar structure transformation that seems to have precipitated along the grain boundaries in the molybdenum-lean regions. In similar samples, homogenized at 800°C for 24 hours and tested at 650°C, the backscattered-electron scanning electron microscopy images revealed a composite structure of lamellar phase and nano-scale molybdenum-rich and-lean phases along the grain boundaries. These phases may have been responsible for the lowering of the flow stress in the material observed in the Phase 1 work. For comparison, the samples homogenized at 1000°C for 16 hours showed no such transformations.

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“…This sample is transverse to the rolling direction, where more pronounced chemical bands would be less likely to be observed. However, significant chemical banding in the transverse direction has been observed previously on similar rolled U-10Mo foils [14]. Furthermore, grain boundaries appear much lighter in contrast to central regions of grains, likely the result of Mo segregation during the alloying process.…”

Section: Optical Metallographymentioning

confidence: 51%

“…Likewise, the interface between the Zr and the U-Mo alloy reveals two prominent features as a result of the hot co-rolling and HIP bonding fabrication process. According to the literature [4][5][6]14], these features are likely a uniform UZr 2 phase and globular Mo 2 Zr precipitates. Previous studies have indicated that these intermetallics range from 1.75 µm to 2.84 µm in thickness [4], with the volume fraction of Mo 2 Zr precipitates increasing with decreased annealing temperature [5].…”

Section: Optical Metallographymentioning

confidence: 93%

Development and Validation of Capabilities to Measure Thermal Properties of Layered Monolithic U–Mo Alloy Plate-Type Fuel

et al. 2014

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The uranium-molybdenum (U-Mo) alloy in a monolithic form has been proposed as one fuel design capable of converting some of the world's highest power research reactors from the use of high enriched uranium to low enriched uranium. One aspect of the fuel development and qualification process is to demonstrate appropriate understanding of the thermal-conductivity behavior of the fuel system as a function of temperature and expected irradiation conditions. The purpose of this paper is to verify functionality of equipment installed in hot cells for eventual measurements on irradiated uranium-molybdenum (U-Mo) monolithic fuel specimens, refine procedures to operate the equipment, and validate models to extract the desired thermal properties. The results presented here demonstrate the adequacy of the equipment, procedures, and models that have been developed for this purpose based on measurements conducted on surrogate depleted uranium-molybdenum (DU-Mo) alloy samples containing a Zr diffusion barrier and clad in aluminum alloy 6061 (AA6061). The results are in excellent agreement with thermal property data reported in the literature for similar U-Mo alloys as a function of temperature.

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Characterization of U-Mo Foils for AFIP-7

Abstract: This document was printed on recycled paper.

Cited by 9 publications

References 0 publications

Thermomechanical process optimization of U-10wt% Mo – Part 2: The effect of homogenization on the mechanical properties and microstructure

Thermomechanical process optimization of U-10wt% Mo – Part 2: The effect of homogenization on the mechanical properties and microstructure

Influence of Homogenization on the Mechanical Properties and Microstructure of the U-10Mo Alloy

Development and Validation of Capabilities to Measure Thermal Properties of Layered Monolithic U–Mo Alloy Plate-Type Fuel

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