Microstructure evolution and grain size distribution in nanocrystalline FeNbBCu from synchrotron XRD and TEM analysis

► The grain size distribution of the nanocrystalline alloy was obtained by different methodologies. ► The microstructural evolution has been obtained in-situ from synchrotron XRD. ► The experimental XRD are modeled by Debye equation leading to good agreement. ► A model describing the nucleation and growth of the nanocrystals is presented.