The impact of anisotropic thermal expansion on the isothermal annealing of polycrystalline α -uranium

Journal Article · 31 January 2022 · Computational Materials Science

DOI: https://doi.org/10.1016/j.commatsci.2022.111217 · OSTI ID:1889727

Jokisaari, Andrea M.  ^[1]; Mahbuba, Khadija  ^[2]; Wang, Yuhao  ^[3]; Beeler, Benjamin  ^[2]

---

1. Idaho National Lab. (INL), Idaho Falls, ID (United States)
2. North Carolina State University, Raleigh, NC (United States)
3. University of Michigan, Ann Arbor, MI (United States)

Although grain growth impacts microstructural evolution in a wide variety of materials systems, the effect of anisotropic thermal expansion on grain boundary mobility and texture evolution has not been widely studied. Anisotropic thermal expansion occurs in multiple non-cubic metals, and the thermomechanical processing behavior of these materials can be better understood with further study into the impact of thermal expansion on grain boundary mobility and texture evolution. In this work, we develop a mesoscale phase field model of grain growth that includes the effect of anisotropic thermal expansion, which is applied to study polycrystalline α-uranium, a highly anisotropic metal. Three-dimensional simulations on polycrystalline a-uranium with and without thermal expansion eigenstrains are performed to study the grain boundary mobility and texture evolution as a function of temperature. A strain-free temperature of 933 K is selected, and the system is studied at within the range of 873 – 933 K at intervals of ten degrees, resulting in increasing thermal eigenstrain with decreasing temperature. We also estimate a grain boundary mobility prefactor and activation energy based on existing experimental data of isothermal annealing of α-uranium. The grain boundary mobility is found to display significant deviation from Arrhenius behavior with the inclusion of thermal expansion eigenstrain as the amount of thermal eigenstrain (and thus elastic strain energy within the system) increases. This result explains an experimentally observed grain boundary mobility deviation from Arrhenius behavior. Furthermore, the texture evolution is affected, such that the grain orientations become less random with increasing thermal eigenstrain, which could explain experimentally observed texture behavior. These results indicate that the effect of thermal expansion should be considered when predicting the thermomechanical processing behavior of α-uranium and other materials with anisotropic thermal expansion.

• Research Organization: Idaho National Laboratory (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE); USDOE Laboratory Directed Research and Development (LDRD) Program
• Grant/Contract Number: AC07-05ID14517
• OSTI ID: 1889727
• Report Number(s): INL/JOU-21-64894-Rev000
• Journal Information: Computational Materials Science, Journal Name: Computational Materials Science Journal Issue: - Vol. 205; ISSN 0927-0256
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English