The present invention provides a Fe—B—Si
system amorphous
alloy thin strip excellent in high
magnetic flux density,
thermal stability, amorphous
formability improved workability and low core loss. The present invention further provides a Fe—B—Si
system amorphous
alloy thin strip which has the reduced cost without using high purity iron resources such as an
electrolytic iron as iron resources used in an amorphous
alloy thin strip, and also has core loss less than 0.10 W / kg at W13 / 50 in soft magnetic property in alternating-current field. The Fe—B—Si
system amorphous alloy thin strip according to the present invention contains an appropriate amounts of N, C, P to improve
thermal stability, amorphous
formability, workability (
brittleness), and core loss without deteriolating
magnetic flux density, and contains, in atomic %, B: 5-25%, Si: 1-30%, N: 0.001-0.2%, C: 0.003-10%, P: 0.001-0.2% and the balance being Fe and unavoidable impurities, and optionally contains Co or Ni substituted to less than 15% of the Fe amount, or Cr at less than 5% substituted to the Fe amount. Further, Mn: 0.15-0.5
mass %, S: 0.004-0.05
mass % can be included.