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

1. 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 number of protrusions P in the free solidified surface of the Fe-based nanocrystalline alloy ribbon, each having a depression at a central part thereof, is 1.2 or less per 100 mm 2 of area,

warpage of the Fe-based amorphous alloy ribbon in the width direction is 0.30 mm or less per 10 mm of width, and

the Cu alloy is a Cu—Be alloy containing Be in an amount of from 1.6% by mass to 2.2% by mass with respect to the entire Cu—Be alloy, wherein the molten Fe-based alloy has an alloy composition represented by the following Composition Formula (A):

Fe 100-a-b-c-d-e Cu a Si b B c Nb d C e   Composition Formula (A):

wherein, in Composition Formula (A), each of 100-a-b-c-d-e, a, b, c, d, and e represents an atomic percent of a relevant element when a total of Fe, Cu, Si, B, Nb, and C is 100 atom %, and a, b, c, d, and e satisfy 0.30≤a≤2.00, 13.00≤b≤16.00, 6.00≤c≤11.00, 2.00≤d≤4.00, and 0.04≤e≤0.40, respectively.

2. 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,

a number of protrusions P in the free solidified surface of the Fe-based nanocrystalline alloy ribbon, each having a depression at a central part thereof, is 1.2 or less per 100 mm 2 of area,

warpage of the Fe-based amorphous alloy ribbon in the width direction is 0.30 mm or less per 10 mm of width, and

the Cu alloy is a Cu—Be alloy containing Be in an amount of from 1.6% by mass to 2.2% by mass with respect to the entire Cu—Be alloy, wherein the molten Fe-based alloy has an alloy composition represented by the following Composition Formula (A):

Fe 100-a-b-c-d-e Cu a Si b B c Nb d C e   Composition Formula (A):

wherein, in Composition Formula (A), each of 100-a-b-c-d-e, a, b, c, d, and e represents an atomic percent of a relevant element when a total of Fe, Cu, Si, B, Nb, and C is 100 atom %, and a, b, c, d, and e satisfy 0.30≤a≤2.00, 13.00≤b≤16.00, 6.00≤c≤11.00, 2.00≤d≤4.00, and 0.04≤e≤0.40, respectively.