CALPHAD TYPE MODELLING OF PHASE DIAGRAMS OF NANOMATERIALS

CALPHAD approach is a very useful technique for calculation of phase diagrams of bulk materials based on thermodynamic databases containing Gibbs energy pure elements, mixtures and compounds as a function of composition, temperature and pressure. In order to extend the use of CALPHAD approach to small metallic particles on sub-micron and nano scale, due to the surface effect, the Gibbs energy should be expressed with an additional parameter: the particle size. The ab-initio calculations are used to model theoretically the surface effects by means of surface energy and surface tension calculations. The Ni-Sn system was used as an example in the theoretical modelling of Ni-Sn phase diagram for nanosystems by means of combination of CALPHAD and ab-initio calculations.