LAUSR

Abstract Core-shell structured magnetic composites containing a FeSiAl core and oxides shell were prepared by HNO3 oxidation. Microstructure evolution and phase composition of the insulation coatings correlated to magnetic properties have been revealed during high-temperature annealing. Results indicate that spherical nanoparticles composed of iron oxides may form on the coating surface after annealing at 700 °C followed by growing into larger wirelike particles by raising annealing temperature to 800 °C. The nucleation mechanism of the nanoparticles was presented according to the LaMer model and the growth regimes can be attributed to aggregative growth by mutual fusion. Largely enhanced magnetic properties (μe = 167.3, Pcv = 205.6 mW/cm3) have been achieved annealed at 750 °C.