Atomistic study of structure and stability of thin Ni films on Fe surfaces

The adhesion and residual strain of Ni thin-film coatings on g-Fe and a-Fe substrates are investigated by ab initio calculations using density functional theory (DFT) in the local density approximation (LDA), and by an empirical FinnisSinclair type interatomic potential utilizing angle dependent terms. The results from the DFT and empirical potentials agree for strained coherent interfaces. The phase stability and structural transitions are studied for incoherent interfaces via molecular dynamics and static relaxation methods. It is found that the transition in thin Ni films from bcc to fcc structure occurs for three or four monolayers and is accompanied by a reorientation of the Ni film with respect to the Fe substrate.