Nucleation dynamics in Al solidification with Al-Ti refiners by molecular dynamics simulation

Nucleation dynamics at the beginning Al of solidification with Al-Ti refiners is investigated by molecular dynamics (MD) simulation. Planar growth via uniform adsorption of Al atoms is observed on the most of examined planes of D0(22)- and L1(2)-Ak(3)Ti crystals. On the other hands, small islands of Al crystal appear locally on (1 1 2) plane of the D0(22)-Al3Ti and island-like growth follows subsequently. It is revealed that the arrangement of Al and Ti atoms at the Al3Ti surface is dominant factor of growth behavior and growth velocity. In particular, distribution of stable sites for Al adatoms at the surface of Al3Ti determines planar or island-like growth in the beginning of Al solidification on the Al3Ti heterogeneous nucleation site particles.