Soft magnetic alloy ribbon and its production method, and magnetic device having soft magnetic alloy ribbon

1. A method for producing a soft magnetic alloy ribbon having a composition represented by Fe 100-x-y-z A x B y X z , wherein A is Cu and/or Au, X is at least one element selected from the group consisting of Si, S, C, P, Al, Ge, Ga and Be, and x, y and z are numbers (by atomic %) meeting the conditions of 0<x≦5, 12≦y≦22, 1≦z≦10, and x+y+z≦25, and comprising a matrix phase in which fine crystal grains having an average diameter of 60 nm or less are dispersed at a volume fraction of 50% or more in an amorphous phase, and an amorphous layer having a higher B concentration than in said matrix phase by 0.5 atomic % or more in a region at a depth 30-130 nm from the surface of the ribbon, comprising the steps of (1) ejecting an alloy melt having said composition onto a rotating cooling roll for quenching, to form a primary fine-crystalline alloy ribbon having a matrix phase, in which fine crystal nuclei having an average diameter of 30 nm or less are dispersed at a volume fraction of more than 0% and less than 30% in an amorphous phase, said primary fine-crystalline alloy ribbon being stripped from said cooling roll when reaching a temperature of 170-350° C.; and then (2) annealing said primary fine-crystalline alloy ribbon in an atmosphere containing an oxygen concentration of 6-18 vol. %.

2. A method for producing a soft magnetic alloy ribbon having a composition represented by Fe 100-x-y-z A x B y X z , wherein A is Cu and/or Au, X is at least one element selected from the group consisting of Si, S, C, P, Al, Ge, Ga and Be, and x, y and z are numbers (by atomic %) meeting the conditions of 0<x≦5, 10≦y≦22, 1≦z≦10, and x+y+z≦25, and comprising a matrix phase in which fine crystal grains having an average diameter of 60 nm or less are dispersed at a volume fraction of 50% or more, and a surface oxide film, part of said oxide film being a layer having a lower B concentration than the average B concentration of said matrix phase and a layer having a lower Cu concentration than the average Cu concentration in said matrix phase, wherein the average B concentration in a depth up to 10 nm from the surface is 1 atomic % or less, wherein the B/Fe atomic ratio in the oxide film in a depth up to 10 nm from the surface is 1/20 or less, wherein the average Cu concentration in a depth up to 10 nm from the surface is 2 atomic % or less, wherein the Cu/Fe atomic ratio in a depth up to 10 nm from the surface is 1/10 or less, and wherein the average Fe concentration in a depth up to 10 nm from the surface is 10 atomic % or more; comprising the steps of (1) ejecting an alloy melt having said composition onto a rotating cooling roll for quenching, to form a primary fine-crystalline alloy ribbon having a matrix phase, in which fine crystal nuclei having an average diameter of 30 nm or less are dispersed at a volume fraction of more than 0% and less than 30% in an amorphous phase, said primary fine-crystalline alloy ribbon being stripped from said cooling roll when reaching a temperature of 170-350° C.; and then (2) annealing said primary fine-crystalline alloy ribbon in an atmosphere having an oxygen concentration of 6-18 vol. %.