Local chemical ordering within the incubation period as a trigger for nanocrystallization of a highly supercooled Ti-based liquid

Abstract

In the present work we study nanocrystallization of the Ti50Ni23Cu22Sn5 alloy within the supercooled liquid region by using a state-of-the-art experimental technique with elemental mapping at near-atomic resolution especially focusing on the incubation period which is still poorly understood from both the theoretical and experimental viewpoint. Molecular dynamics (MD) simulation results performed for the Ti55Ni45 liquid acting as a simplified model system of the (Ti,Sn)55(Ni,Cu)45 alloy illustrate the process of nucleation and provide some additional suggestions. The experiment and MD results indicate formation of nanometer-range chemical rearrangements which are supposed to reduce the energy barrier in the complex energy landscape finally leading to a high density of homogeneously nucleating crystallites after the completion of a macroscopically observed incubation period.