High-Temperature Mechanical and Dynamical Properties of γ-(U,Zr) Alloys

Abstract

High-temperature body-centered cubic (BCC) (Formula presented.) -U is effectively stablized by (Formula presented.) -(U,Zr) alloys that also make it feasible to use it as a nuclear fuel. However, relatively little research has focused on (Formula presented.) -(U,Zr) alloys due to their instability at room temperature. The effect of Zr composition on its mechanical properties is not clear yet. Herein, we perform molecular dynamics simulations to investigate the mechanical and dynamical stabilities of (Formula presented.) -(U,Zr) alloys under high temperatures, and we calculate the corresponding lattice constants, various elastic moduli, Vickers hardness, Debye temperature, and dynamical structure factor. The results showed that (Formula presented.) -U, (Formula presented.) -Zr, and (Formula presented.) -(U,Zr) are all mechanically and dynamically stable at 1200 K, which is in good agreement with the previously reported high-temperature phase diagram of U-Zr alloys. We found that the alloying treatment on (Formula presented.) -U with Zr can effectively improve its mechanical strength and melting points, such as Vickers hardness and Debye temperature, making it more suitable for nuclear reactors. Furthermore, the Zr concentrations in (Formula presented.) -(U,Zr) alloys have an excellent effect on these properties. In addition, the dynamical structure factor reveals that (Formula presented.) -U shows different structural features after alloying with Zr. The present simulation data and insights could be significant for understanding the structures and properties of UZr alloy under high temperatures.