Method for producing fe-based nanocrystalline alloy ribbon, method for producing magnetic core, fe-based nanocrystalline alloy ribbon, and magnetic core

A method for producing an Fe-based nanocrystalline alloy ribbon, the method comprising:

• supplying a molten Fe-based alloy onto a rotating chill roll, and rapidly solidifying the molten Fe-based alloy that has been supplied onto the chill roll, thereby obtaining an Fe-based amorphous alloy ribbon having a free solidified surface and a roll contact surface, and having a width of from 5 mm to 65 mm and a thickness of from 10 μm to 15 μm;
• and
• heat-treating the Fe-based amorphous alloy ribbon, thereby obtaining an Fe-based nanocrystalline alloy ribbon,
• wherein an outer peripheral part of the chill roll is composed of a Cu alloy, and a thermal conductivity of the outer peripheral part is in a range of from 110 W/(m·K) to 225 W/(m·K), and a Vickers hardness of the outer peripheral part is in a range of from 250 HV to 400 HV.

A method for producing a magnetic core comprising a wound body C in which an Fe-based nanocrystalline alloy ribbon is wound via an insulation layer, the method comprising:

• supplying a molten Fe-based alloy onto a rotating chill roll, and rapidly solidifying the molten Fe-based alloy that has been supplied onto the chill roll, thereby obtaining an Fe-based amorphous alloy ribbon having a free solidified surface and a roll contact surface, and having a width of from 5 mm to 65 mm and a thickness of from 10 μm to 15 μm;
• forming the insulation layer on the free solidified surface of the Fe-based amorphous alloy ribbon:
• winding the Fe-based amorphous alloy ribbon having the insulation layer formed thereon, thereby obtaining a wound body A in which the Fe-based amorphous alloy ribbon is wound via the insulation layer;
• and
• heat-treating the wound body A, thereby obtaining the wound body C,
• wherein an outer peripheral part of the chill roll is composed of a Cu alloy, a thermal conductivity of the outer peripheral part is in a range of from 110 W/(m·K) to 225 W/(m·K), and a Vickers hardness of the outer peripheral part is in a range of from 250 HV to 400 HV.

An Fe-based nanocrystalline alloy ribbon, comprising;

• a free solidified surface;
• and a roll contact surface, wherein:
• a number of protrusions P in the free solidified surface, each having a depression at a central part thereof, is 1.2 or less per 100 mm2 of area,
• a width of the ribbon is from 5 mm to 65 mm,
• a thickness the ribbon is from 10 μm to 15 μm, and warpage in a width direction is 0.30 mm or less per 10 mm of width.