Amorphous alloy composition

1. An amorphous alloy composition of the formula Fe a B b Si c P x Cu y , wherein 73 at %≦a≦85 at %, 9.65 at %≦b≦22 at %, 9.65 at %≦b+c≦24.75 at %, 0.25 at %≦x≦5 at %, 0 at %<y≦0.35 at %, and 0<y/x≦0.5.

2. The amorphous alloy composition as recited in claim 1 , further comprising 2 at % or less of C, wherein b is the total amount of B and C.

3. The amorphous alloy composition as recited in claim 2 , further comprising 30 at % or less of at least one element selected from the group consisting of Co and Ni, wherein a is the total amount of Fe and the at least one element.

4. The amorphous alloy composition as recited in claim 3 , further comprising 3 at % or less of at least one element selected from the group consisting of V, Ti, Mn, Sn, Zn, Y, Zr, Hf, Nb, Ta, Mo and a rare-earth element, wherein a is the total amount of Fe and the at least one elements.

5. The amorphous alloy composition as recited in claim 4 , wherein the amorphous alloy composition has a ribbon shape having a thickness in a range of from 30 μm to 300 μm.

6. The amorphous alloy composition as recited in claim 3 , wherein the amorphous alloy composition has a ribbon shape having a thickness in a range of from 30 μm to 300 μm.

7. The amorphous alloy composition as recited in claim 2 , further comprising 3 at % or less of at least one element selected from the group consisting of V, Ti, Mn, Sn, Zn, Y, Zr, Hf, Nb, Ta, Mo and a rare-earth element, wherein a is the total amount of Fe and the at least one element.

8. The amorphous alloy composition as recited in claim 7 , wherein the amorphous alloy composition has a ribbon shape having a thickness in a range of from 30 μm to 300 μm.

9. The amorphous alloy composition as recited in claim 2 , wherein the amorphous alloy composition has a ribbon shape having a thickness in a range of from 30 μm to 300 μm.

10. The amorphous alloy composition as recited in claim 1 , further comprising 30 at % or less of at least one element selected from the group consisting of Co and Ni, wherein a is the total amount of Fe and the at least one element.

11. The amorphous alloy composition as recited in claim 10 , further comprising 3 at % or less of at least one element selected from the group consisting of V, Ti, Mn, Sn, Zn, Y, Zr, Hf, Nb, Ta, Mo and a rare-earth element, wherein a is the total amount of Fe and the at least one elements.

12. The amorphous alloy composition as recited in claim 11 , wherein the amorphous alloy composition has a ribbon shape having a thickness in a range of from 30 μm to 300 μm.

13. The amorphous alloy composition as recited in claim 10 , wherein the amorphous alloy composition has a ribbon shape having a thickness in a range of from 30 μm to 300 μm.

14. The amorphous alloy composition as recited in claim 1 , further comprising 3 at % or less of at least one element selected from the group consisting of V, Ti, Mn, Sn, Zn, Y, Zr, Hf, Nb, Ta, Mo and a rare-earth element, wherein a is the total amount of Fe and the at least one element.

15. The amorphous alloy composition as recited in claim 14 , wherein the amorphous alloy composition has a ribbon shape having a thickness in a range of from 30 μm to 300 μm.

16. The amorphous alloy composition as recited in claim 1 , wherein the amorphous alloy composition has a ribbon shape having a thickness in a range of from 30 μm to 300 μm.

17. The amorphous alloy composition as recited in claim 1 , wherein the amorphous alloy composition has a plate-like shape having a thickness of at least 0.5 mm or a rod-like shape having an outside diameter of at least 1 mm.

18. The amorphous alloy composition as recited in claim 1 , wherein the amorphous alloy composition has a shape including a plate-like portion or a rod-like portion having a thickness of at least 1 mm.

19. The amorphous alloy composition as recited in claim 1 , wherein 0.01 at %≦y≦0.35 at %.