Microstructure,magnetic and micromechanical properties of Fe-Cu-Nb-Si-B melt-spun ribbons

Fe_78.3Cu_0.6Nb_2.6Si_9.5B₉ melt-spun ribbons of 6-8 mm in width and 30-40 μ_m in thickness were produced by using a single roller melt spinning technique machine. The melt-spun ribbons have the direct current (DC) magnetic properties of saturation flux B_s=1.06 T, remanence B_r=0.39 T, coercivity H_c=3.53 A·m^-1 and maximum permeability μ_m=2.43 mH·m^-1 and the alternating current magnetic properties of core loss P_{0.5 T/1 kHz}=22.2 W·kg^-1, P_{0.2 T/100 kHz}=864 W·kg^-1 and corresponding efficient magnetic permeability μ_e=833 and 1225. Field emission high resolution scanning electron microscopy results indicate that the melt-spun ribbons prepared at different technical parameters show different crystallization degrees and fracture morphology characteristics. The fracture surface morphology of the amorphous-nanocrystallized ribbons is composed of a mirror zone, a mist zone, a hackle zone, and a river-pattern zone, while the crystallized ribbons exhibit intergranular embrittlement. The microhardness and elastic modulus of the amorphous-nanocrystallized ribbons measured with a nano-indenter probe are lower than those of the crystallized ribbons. The fracture toughness of the melt-spun ribbons was semi-quantitatively determined by using a self-designed gauge based on the Luborsky method.