Structural evolutionary process and interrelation for FeSiBNbCuMo nanocrystalline alloy

Abstract

The precipitation phase transformation, nanostructure and magnetic domain evolution of Fe76Si13B8Nb1.5Cu1Mo0.5 alloy on annealing process has been investigated systematically by the DSC, XRD, TEM, HAADF-STEM, APT and MOKE. It was found that ribbons in the amorphous state exhibit typical stress domains with wide arc domains and fingerprint-like domains, and Cu clusters that act as heterogeneous nucleation sites of α-Fe(Si) grains prior precipitate well before the onset of primary crystallization. With the annealing temperature increasing, α-Fe(Si) and Fe3B phases precipitated successively, which first led to the broadening of magnetic domains and the decrease of the number of domain walls, and then the emergence of new wall pinning sites. Accordingly, the Cu cluster - nanograin - magnetic domain correlation model based on the experimental results was established, from which could intuitively reflect the evolution of atoms, clusters, grains and magnetic domains of the alloy. Moreover, an associated variation mechanism of the soft magnetic properties with the microstructure and magnetic domain was also obtained, which could provide a good guide for future performance optimization and application of Fe-based nanocrystalline alloys.