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Title: Equation of state, phase stability, and phase transformations of uranium-6 wt.% niobium under high pressure and temperature

Abstract

In-situ time-of-flight neutron diffraction experiments were conducted on the uranium-niobium alloy with 6 wt. % Nb (U–6Nb) at pressures up to 4.7 GPa and temperatures up to 1073 K. Upon static compression at room temperature, the monoclinic structure of U–6Nb (α" U–6Nb) remains stable up to the highest experimental pressure. Based on the pressure-volume measurements at room temperature, the least-squares fit using the finite-strain equation of state (EOS) yields an isothermal bulk modulus of B 0 = 127±2 GPa for the α"-phase of U–6Nb. The calculated zero-pressure bulk sound speed from this EOS is 2.706±0.022 km/s, which is in good agreement with the linear extrapolation of the previous Hugoniot data above 12 GPa for α" U–6Nb, indicating that the dynamic response under those shock-loading conditions is consistent with the stabilization of the initial monoclinic phase of U-6Nb. Upon heating at ambient and high pressures, the metastable α" U–6Nb exhibits complex transformation paths leading to the diffusional phase decomposition, which are sensitive to applied pressure, stress state, and temperature-time path. These findings provide new insight into the behavior of atypical systems such as U-Nb and suggest that the different U-Nb phases are separated by rather small energies and hence highly sensitivemore » to compositional, thermal, and mechanical perturbations.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1482941
Report Number(s):
LA-UR-18-22186
Journal ID: ISSN 0021-8979
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 123; Journal Issue: 17; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; U-Nb alloys; equation of state; phase transformation; high pressure

Citation Formats

Zhang, Jianzhong, Vogel, Sven C., Brown, Donald William, Clausen, Bjorn, and Hackenberg, Robert Errol. Equation of state, phase stability, and phase transformations of uranium-6 wt.% niobium under high pressure and temperature. United States: N. p., 2018. Web. doi:10.1063/1.5032308.
Zhang, Jianzhong, Vogel, Sven C., Brown, Donald William, Clausen, Bjorn, & Hackenberg, Robert Errol. Equation of state, phase stability, and phase transformations of uranium-6 wt.% niobium under high pressure and temperature. United States. doi:10.1063/1.5032308.
Zhang, Jianzhong, Vogel, Sven C., Brown, Donald William, Clausen, Bjorn, and Hackenberg, Robert Errol. Fri . "Equation of state, phase stability, and phase transformations of uranium-6 wt.% niobium under high pressure and temperature". United States. doi:10.1063/1.5032308.
@article{osti_1482941,
title = {Equation of state, phase stability, and phase transformations of uranium-6 wt.% niobium under high pressure and temperature},
author = {Zhang, Jianzhong and Vogel, Sven C. and Brown, Donald William and Clausen, Bjorn and Hackenberg, Robert Errol},
abstractNote = {In-situ time-of-flight neutron diffraction experiments were conducted on the uranium-niobium alloy with 6 wt. % Nb (U–6Nb) at pressures up to 4.7 GPa and temperatures up to 1073 K. Upon static compression at room temperature, the monoclinic structure of U–6Nb (α" U–6Nb) remains stable up to the highest experimental pressure. Based on the pressure-volume measurements at room temperature, the least-squares fit using the finite-strain equation of state (EOS) yields an isothermal bulk modulus of B0 = 127±2 GPa for the α"-phase of U–6Nb. The calculated zero-pressure bulk sound speed from this EOS is 2.706±0.022 km/s, which is in good agreement with the linear extrapolation of the previous Hugoniot data above 12 GPa for α" U–6Nb, indicating that the dynamic response under those shock-loading conditions is consistent with the stabilization of the initial monoclinic phase of U-6Nb. Upon heating at ambient and high pressures, the metastable α" U–6Nb exhibits complex transformation paths leading to the diffusional phase decomposition, which are sensitive to applied pressure, stress state, and temperature-time path. These findings provide new insight into the behavior of atypical systems such as U-Nb and suggest that the different U-Nb phases are separated by rather small energies and hence highly sensitive to compositional, thermal, and mechanical perturbations.},
doi = {10.1063/1.5032308},
journal = {Journal of Applied Physics},
number = 17,
volume = 123,
place = {United States},
year = {Fri May 04 00:00:00 EDT 2018},
month = {Fri May 04 00:00:00 EDT 2018}
}

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Works referenced in this record:

Finite strain isotherm and velocities for single-crystal and polycrystalline NaCl at high pressures and 300�K
journal, January 1978