Surface structure and composition of Ni–Ti alloys and their influence on the temperature-dependent segregation behavior

Atomistic modeling of segregation in Ni–Ti alloys is performed using the Bozzolo–Ferrante–Smith (BFS) method for alloys. It is found that Ti segregation to the surface decreases rapidly even for small increases in Ni concentration. A competing process is identified in the vicinity of surface defects, leading to excess Ti coverage of the exposed surface and the creation of Ti-covered pits. A simple explanation based on an atom-by-atom energy analysis is found to satisfactorily explain the observed effects.