Atomistic modelling of reversible phase transformations in Ni–Ti alloys: A molecular dynamics study

Ni–Ti thin films for micro actuators is the focus of intense research. Such films have precipitates with a unique micro-structure. By molecular dynamics simulation (MDS) using embedded-atom potentials, we construct nano-sized Ni–Ti model systems including plate shape precipitates. First, the energetics of such plate precipitates is evaluated. The simulations show that there is a lower energy precipitate which is actually observed in experimental studies. Second, uniaxial-tensile loading is conducted for the MDS model which contains the precipitate. For the relaxed state, the precipitate sufficiently matches the Ni–Ti parent phases at the interfaces, whereas during the loading, mismatch as well as nucleation of martensite occurs there.