In situ monitoring of disorder-order A1-L10 FePt phase transformation in nanocomposite FePt-based alloys

The FePt disorder-order phase transformation in FePt-based systems with B and Nb added to the composition has been in situ monitored using energy dispersive X-ray diffraction of the synchrotron radiation. The technique allows to observe in real time the onset of the transition and the full profile refinement of the obtained XRD patterns facilitate the separation of overlapping A1 cubic and L10 tetragonal FePt and to calculate the integral relative fraction of both phases at each step of temperature from 490 °C up to 750 °C. It is shown that the resulting phase structure and L10 abundance depends on the initial as-cast state and stoichiometry.