Molecular dynamics investigation of the structural stability of body-centered cubic zirconium nanofilms

The influence of the film thickness and temperature on the phase stability of body-centered cubic (BCC) zirconium in infinite films with different crystallographic orientations has been investigated using the molecular dynamics method with a many-body interatomic interaction potential obtained within the embedded atom model. The calculations have been performed for BCC zirconium films with thicknesses ranging from 2 to 13 nm and with low Miller indices (001), (110), and (111). It has been shown that the BCC(001) zirconium nanofilms with thicknesses up to 6.1 nm, which are formed in the temperature range from 500 to 1300 K, undergo a reorientational phase transition through an intermediate metastable face-centered cubic (FCC) phase with the subsequent transformation into the hexagonal close-packed (HCP) structure (BCC(001)-FCC-BCC??(110)-HCP). When the temperature of initialization of the films is 500 K and below, the BCC-FCC transformation is observed and the FCC phase remains stable. The (110) films are characterized by a strong dependence of the temperature of the BCC-HCP phase transition on the film thickness up to values of 5.8 nm. In the (111) films, the amorphization of the initial BCC phase with the subsequent formation of the BCC phase with a twin structure is observed.