Investigations on mechanical, thermodynamic and surface properties of U-Si alloys

The investigation of U-Si alloys as advanced technology fuels or accident tolerance fuels (ATFs) has gained momentum due to their higher uranium density and exceptional thermal conductivity. Density functional theory (DFT) calculations were used to examine the mechanical, thermodynamic and surface properties of U-Si alloys. Voigt-Reuss-Hill model was used to evaluate the mechanical properties such as Young's modulus, shear modulus, bulk modulus and so on. The results suggest that U3Si2 possesses an inherent brittleness, as opposed to the remaining U-Si alloys which demonstrate reliable ductility. In comparison to the hardness of other U-Si alloys (40-80 GPa), U3Si2 exhibits a significantly lower hardness (similar to 10 GPa). The results of anisotropy show that U3Si2 exhibits a lower anisotropy compared to USi2 (I41/amd) and U3Si (Pm-3m). Also, based on these mechanical properties, the sound velocity and Debye temperature are determined. Additionally, the study calculates the internal energy, Helmholtz free energy, entropy and heat capacity as a function of temperature, which is beneficial for fuel design and other applications. The surface energies and work function are investigated comprehensively for 161 surface slab models and used to obtain other surface properties, including equilibrium morphology, dominant surface orientations, area-weighted surface energy and area-weighted work function.

Automated summary

The mechanical, thermodynamic, and surface properties of U-Si alloys were investigated using density functional theory calculations. The results showed that U3Si2 exhibited brittleness, while the remaining U-Si alloys demonstrated reliable ductility. The study also calculated the sound velocity, Debye temperature, and surface properties of the alloys.