Modeling rapid liquid/solid and solid/liquid phase transformations in Al alloys

A recently developed thermodynamic model for describing the 'contact conditions' (concentrations at an interface of the two adjacent phases) is implemented in a kinetic model for liquid/solid phase transformations. The resulting integrated model describes the concentration profiles in the liquid and solid phase during the phase transformation over a large range of solidification front velocities. Examples are shown for steady state solidification in aluminum alloys. The results are in good agreement with experimental data from the literature and the well known continuous growth model by Aziz. In addition to earlier models, transient states can be described. An example is shown for a solidification front that is momentarily disturbed, i.e. set off-equilibrium. One of the results is the time for local re-equilibration at the interface which is of the order of 20 ps for solidification. First results for describing melting are also shown and discussed.