To provide an Fe based nanocrystal soft magnetic alloy having high saturation magnetic flux density and low magnetostriction, and particularly suitable for a cut core, to provide an amorphous alloy thin strip used for producing the Fe based nanocrystal soft magnetic alloy, to provide a method for producing the Fe based nanocrystal soft magnetic alloy, and to provide a high performance magnetic component using the same.

The high Bs-low magnetic strain Fe based nanocrystal soft magnetic alloy has a composition expressed by general formula: Fe100-x-y-zAxMaSiyBz (atomic%); wherein, A denotes at least one kind of element selected from Cu and Au; M denotes at least one kind of element selected from Ti, V, Zr, Nb, Mo, Hf, Ta and W; and (x),(y),(a) and (z) satisfy 0x2, 13y18, 0a1.5, 4z10, and x+y+a+z25, respectively, and is composed of bcc Fe-Si crystal grains with the average grain diameter of 120 nm and an amorphous phase, and in which the bcc Fe-Si crystal grains occupy 50% of the structure by volume fraction, saturated magnetic flux density Bs satisfies 1.4T, and a saturation magnetostriction constant s lies in the range of -3.510-6 to +3.510-6.