Effect of intra- and intergranular hydride precipitation on phonon thermal transport behavior of zirconium: A molecular dynamics study

Hydride precipitation significantly influences the thermal properties of zirconium (Zr)-based components. In this study, non-equilibrium molecular dynamics simulations in conjunction with the Müller-Plathe algorithm were conducted to investigate the effects of hydride precipitates on thermal transport behaviour in Zr. The investigation addresses both intragranular and intergranular hydride precipitation, utilizing single-crystal and bicrystal Zr configurations, respectively. The phonon transport properties were characterized by temperature and kinetic energy profiles, Kapitza resistance, interfacial thermal conductance, partial density of states, and phonon participation ratio (PPR). The simulation results conclude that hydride precipitation acts as a phonon scattering center, impeding heat transport due to the mismatch in vibrational modes at the Zr-hydride interface. These effects were more pronounced at the high-energy grain boundary and with an increasing concentration of hydrogen in the hydride phases. Among the different hydride phases (γ, δ, and ε), the ε-hydride demonstrated the highest vibrational localization mode, as evidenced by its lower PPR values. The present study provides atomistic insights into phonon transport in Zr with hydride precipitation, which has important implications for improving thermal management in zirconium-based systems.