Preparation of Amorphous Fe-Si-B and Co-Si-B Alloy Wires by a Melt Extraction Method and Their Mechanical and Magnetic Properties

Amorphous (Fe, Co)–Si–B ternary and quaternary wires were found to be produced over a wire diameter range of 20 to 80 μm by a melt extraction method using a copper wheel with an edge angle of 60 degrees. The wires without any concaves in the transverse cross section were prepared in the extraction condition where the circumferential velocity of the wheel and the rising velocity of the molten alloy are in the range of 20 to 40 m/s and 0.1 to 4.0 mm/s, respectively. The resulting amorphous wires have good bending ductility in the wire diameter range below 80 μm for the Fe₇₅Si₁₀B₁₅ alloy and below 60 μm for the Co_72.5Si_12.5B₁₅ alloy. The thermal stability and mechanical properties except tensile fracture strength (σ_f) for the amorphous wires are nearly the same as those for the melt-spun amorphous ribbons. The σ_f is 3800 MPa for the Fe₇₅Si₁₀B₁₅ wire and 3600 MPa for the Co_72.5Si_12.5B₁₅ wire, being about 10% higher than those for the corresponding ribbon samples because of the low degree of stress concentration resulting from the good smoothness on the outer surface. The magnetic properties of saturation magnetization, coercivity and effective permeability at 1 kHz for the wires are nearly the same as those for the ribbons. The squareness of the hysteresis B–H loop for the Fe–Si–B amorphous wire is better than that for the same Fe-based ribbon and the sharp output voltage due to the reversion of magnetic flux is also observed for the present Fe₇₈Si₁₀B₁₂ amorphous wire. The combined properties of good mechanical properties and unique magnetic properties leading to the generation of the sharp output voltage seem to be promising for the subsequent development of the present fine amorphous wires.