Porosity effect on the thermal and mechanical properties of U-50Zr alloy: A molecular dynamics study

Abstract

The U-50Zr alloy is a promising candidate for helical cruciform fuel application, for the superior performance in neutronics and heat transfer properties. Under in-pile conditions, the formation and aggregation of fission gas products would introduce porosity effect, and further degrade the mechanical-thermal physical properties. However, no porosity model has been established for U-50Zr alloy. In this work, the Young's modulus and lattice conductivity for U-50Zr were predicted via molecular dynamics (MD) simulations with modified embedded atom method potential. The effective Young's modulus was obtained by multi-dimensional elongation tests and Voigt averaging scheme, and the phonon conductivity was computed with reverse non-equilibrium molecular dynamics method. The electron conductivity was estimated by Wiedemann-Franz Law with published resistivity data. To fulfill porosity effect modeling, void generation technique was utilized into the MD models, and effective medium theory was incorporated into the approximations of electron conductivity. Good agreements with experimental data were achieved to verify the research methodology. The semi-empirical models on porosity effects for U-50Zr were established, which could provide preliminary predictions of Young's modulus and thermal conductivity.