Grain boundary enrichment in the FePt polymorphic A1 to L10 phase transformation

A series of Fe54±1Pt46±1 thin films have been sputter-deposited and annealed at various times and temperatures to facilitate the A1 to L10 polymorphic phase transformation. The annealing times span one minute to tens of minutes over temperatures of 300–800 °C. The films were characterized by X-ray and electron diffraction and atom probe tomography. This time–temperature regime provides ‘snap-shots’ into the compositional segregation evolution at the grain boundaries during the polymorphic phase transformation. The as-deposited A1 phase showed a preferential segregation of Pt to the grain boundaries. The reduction of Pt enrichment at the boundaries was observed for all L10 ordered films.