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Agnew, Sean

Publications and source records attributed to Agnew, Sean.

4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Assessing the influence of microstructure on uranium hydride size distributions via small angle neutron scattering

Here, the effect of microstructure on the internal hydriding behavior of both cast (1 mm grain size) and rolled (25 μm grain size) uranium containing hydrogen concentrations between 0 and 1.8 wppm were evaluated via small angle neutron scattering (SANS). Increasing hydrogen content up to 1.8 wppm in the cast uranium only weakly affected the average uranium hydride (UH 3 ) precipitate size, calculated from the SANS data. Conversely, the UH 3 phase fraction was found to strongly depend on the hydrogen content in the same cast samples. A substantially reduced UH 3 particle size distribution was observed in the rolled uranium relative to cast uranium containing the same nominal hydrogen content. It is hypothesized that the suppression of UH 3 formation in the rolled uranium is driven by increased hydrogen trapping at grain boundaries, and theoretical calculations that account for trap density, potency, and hydrogen diffusion kinetics support this hypothesis.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Time resolved in-situ small angle X-ray scattering clarifies the competition between continuous and discontinuous precipitation in U-6wt%Nb

In-situ high energy x-ray scattering experiments enable high temporal resolution investigations of precipitation kinetics; Continuous and discontinuous precipitation are competitive near the TTT nose (~525°C); The incubation time for discontinuous precipitation increases significantly at temperatures below the TTT nose; Additional evidence for the divergent interlamellar spacing was observed at 434°C and 466°C

36 MATERIALS SCIENCE↗