A new method for evaluating embrittlement of an amorphous alloy ribbon is provided. The method includes: pressing a pressurization member from one side to a plurality of positions of an amorphous alloy ribbon; scattering, in the amorphous alloy ribbon, pressurization portions where the pressurization member is pressed to form indentation; and evaluating embrittlement by the number or distribution of pressurization portions where cracks have occurred.

A soft magnetic alloy is represented by a composition formula (Fe.sub.1-xA.sub.x).sub.aSi.sub.bB.sub.cCu.sub.dM.sub.e, wherein A is at least one of Ni and Co, M is one or more selected from the group consisting of Nb, Mo, V, Zr, Hf, and W, and 82.4≤a≤86, 0.2≤b≤2.4, 12.5≤c≤15.0, 0.05≤d≤0.8, 0.4≤e≤1.0, and 0≤x≤0.1 in at %, and has a structure in which crystal grains having a grain size of 60 nm or less are present in an amorphous phase.

A soft magnetic alloy is represented by a composition formula (Fe.sub.1-xA.sub.x).sub.aSi.sub.bB.sub.cCu.sub.dM.sub.e, wherein A is at least one of Ni and Co, M is one or more selected from the group consisting of Nb, Mo, V, Zr, Hf, and W, and 82.4≤a≤86, 0.2≤b≤2.4, 12.5≤c≤15.0, 0.05≤d≤0.8, 0.4≤e≤1.0, and 0≤x≤0.1 in at %, and has a structure in which crystal grains having a grain size of 60 nm or less are present in an amorphous phase.

A production method for water-atomized metal powder includes: in a region in which the average temperature of a molten metal stream is higher than the melting point by 100° C. or more, spraying primary cooling water from a plurality of directions at a convergence angle of 10° to 25°, where the convergence angle is an angle between an impact direction on the molten metal stream of the primary cooling water from one direction and an impact direction on the molten metal stream of the primary cooling water from any other direction; and in a region in which 0.0004 seconds or more have passed after an impact of the primary cooling water and the average temperature of metal powder is the melting point or higher and (the melting point+50° C.) or lower, spraying secondary cooling water on the metal powder under conditions of an impact pressure of 10 MPa or more.

A production method for water-atomized metal powder includes: in a region in which the average temperature of a molten metal stream is higher than the melting point by 100° C. or more, spraying primary cooling water from a plurality of directions at a convergence angle of 10° to 25°, where the convergence angle is an angle between an impact direction on the molten metal stream of the primary cooling water from one direction and an impact direction on the molten metal stream of the primary cooling water from any other direction; and in a region in which 0.0004 seconds or more have passed after an impact of the primary cooling water and the average temperature of metal powder is the melting point or higher and (the melting point+50° C.) or lower, spraying secondary cooling water on the metal powder under conditions of an impact pressure of 10 MPa or more.

A production method for water-atomized metal powder includes: in a region in which the average temperature of a molten metal stream having an Fe concentration of 76.0 at % or more and less than 82.9 at % is 100° C. or more higher than the melting point, spraying primary cooling water at a convergence angle of 10° to 25°, where the convergence angle is an angle between an impact direction on the molten metal stream from one direction and an impact direction on the molten metal stream from any other direction; and in a region in which 0.0004 seconds or more have passed after an impact of the primary cooling water and the average temperature of metal powder is the melting point or higher and (the melting point+100° C.) or lower, spraying secondary cooling water on the metal powder under conditions of an impact pressure of 10 MPa or more.

A production method for water-atomized metal powder includes: in a region in which the average temperature of a molten metal stream having an Fe concentration of 76.0 at % or more and less than 82.9 at % is 100° C. or more higher than the melting point, spraying primary cooling water at a convergence angle of 10° to 25°, where the convergence angle is an angle between an impact direction on the molten metal stream from one direction and an impact direction on the molten metal stream from any other direction; and in a region in which 0.0004 seconds or more have passed after an impact of the primary cooling water and the average temperature of metal powder is the melting point or higher and (the melting point+100° C.) or lower, spraying secondary cooling water on the metal powder under conditions of an impact pressure of 10 MPa or more.

A soft magnetic alloy powder which is a soft magnetic alloy powder having a low coercivity, and with which it is possible to obtain a green compact magnetic core having a high magnetic permeability. A soft magnetic alloy powder including a composition formula (Fe(1−(α+β))X1 αX2 β) (1−(a+b+c+d+e+f)) MaBbPcSidCeSf. XI is one or more elements selected from the group consisting of Co and Ni, X2 is one or more elements selected from the group consisting or Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O and rare earth elements, and M is one or more elements selected from the group consisting of Nb, Hf, Zr, Ta, Mo, W, Ti and V. The amount of each component contained is within a specified range. The amorphous rate X (%) is at least 85%.

A Fe-based amorphous alloy containing subnanometer-scale ordered clusters, and a preparation method and a nanocrystalline alloy derivative thereof. The composition expression of the Fe-based amorphous alloy is Fe.sub.aSi.sub.bB.sub.c(Cu.sub.dX.sub.e)M.sub.fM′.sub.g, and X is at least one of Ti, Zr and Hf, M is at least one of V, Ta and Nb, and M′ at least one of Co, Ni, C, P, Ge, Cr, Mn, W, Zn, Sn, Sb and Mo; a, b, c, d, e, f and g respectively represent the atomic percent (percentage of the number of atoms) of the corresponding element, and satisfy: 74≤a≤82, 8≤b≤15, 4≤c≤10, 0.5≤d≤1.2, 0.4≤e≤1.8, 1≤f≤3.5, 0≤g≤1, 0.8≤e/d≤1.5 and a+b+c+d+e+f+g=100; the Fe-based amorphous alloy is a composite material composed of an amorphous alloy matrix with atoms arranged in complete disorder and ordered atomic clusters having the size ranging from 0.5 nm to 2 nm uniformly dispersed and distributed in the matrix. The Fe-based amorphous alloy has ultrahigh permeability: the permeability at the frequency of 100 kHz is more than 35000, and the saturation flux density more than 1.3 T.

A Fe-based amorphous alloy containing subnanometer-scale ordered clusters, and a preparation method and a nanocrystalline alloy derivative thereof. The composition expression of the Fe-based amorphous alloy is Fe.sub.aSi.sub.bB.sub.c(Cu.sub.dX.sub.e)M.sub.fM′.sub.g, and X is at least one of Ti, Zr and Hf, M is at least one of V, Ta and Nb, and M′ at least one of Co, Ni, C, P, Ge, Cr, Mn, W, Zn, Sn, Sb and Mo; a, b, c, d, e, f and g respectively represent the atomic percent (percentage of the number of atoms) of the corresponding element, and satisfy: 74≤a≤82, 8≤b≤15, 4≤c≤10, 0.5≤d≤1.2, 0.4≤e≤1.8, 1≤f≤3.5, 0≤g≤1, 0.8≤e/d≤1.5 and a+b+c+d+e+f+g=100; the Fe-based amorphous alloy is a composite material composed of an amorphous alloy matrix with atoms arranged in complete disorder and ordered atomic clusters having the size ranging from 0.5 nm to 2 nm uniformly dispersed and distributed in the matrix. The Fe-based amorphous alloy has ultrahigh permeability: the permeability at the frequency of 100 kHz is more than 35000, and the saturation flux density more than 1.3 T.