Nucleation behavior and solid-liquid interfacial energy of polytetrahedral phases

According to classical nucleation theory the nucleation- and phase-selection behavior of undercooled meltallic melts is strongly dependent on the solid-liquid interfacial energy. A structural approach to the modelling of the interfacial energy for simple melt-crystal interfaces (fcc, hcp, bcc) was developed a number of years ago [1-4]. This approach is extended to polytetrahedral phases using numerical simulation. Results of these calculations are presented for different polytetrahedral structures: the tetragonal sigma -phase in Ni-V, the monoclinic phase lambda -Al13Fe4, the orthorhombic phase mu -Al5Fe2 and the icosahedral quasicrystalline I-phase in Al-Pd-Mn. The numerically estimated values for the solid-liquid interfacial energy are compared with results from experiments on the undercooling- and phase-selection behavior.