Theoretical modeling of incongruent phase transitions in uranium dioxide taking into account evaporation into vacuum
Numerical simulation of the dynamics of incongruent phase transitions in uranium dioxide with the account of evaporation into vacuum was carried out. A mathematical model used is based on the description of heat and mass transfer within the condensed phase in the continuum approximation and on the assumption of local thermodynamic equilibrium everywhere including the interfaces between different phases. The mutual influence of the effects of phase transitions’ incongruence on the evaporation surface and in the condensed phase is taken into account. The calculating results show that in condensed phase near the evaporation surface the region with complex phase structures may exist. In particular the onset of melting may occur in the inner material region even under conditions of its surface heating.
Keywords: Numerical simulation, incongruent phase transitions, evaporation into vacuum, laser heating, continuum model of heat and mass transfer, local thermodynamic equilibrium, uranium dioxide.