Molecular dynamics simulations of martensitic fcc-to-hcp phase transformations in strained ultrathin metallic films

We report results of molecular dynamics simulations that reveal fcc -> hcp martensitic transformations in biaxially strained ultrathin films of face-centered cubic metals. We find that martensites nucleate at the surface and grow into the bulk of the film due to dislocation glide; in this process, the magnitudes of the relative atomic slip displacements are identical to those proposed for Bain transformations. Mechanical stability analysis shows that the onset of the phase transformation is consistent with the onset of a shearing instability of the thin film.