Fe-based soft magnetic alloy and dust core using fe-based soft magnetic alloy

1. An Fe-based soft magnetic alloy consisting of:

Fe; and

a component R,

wherein the component R is at least one element selected from the group consisting of P, C, B, and Si,

there is a temperature difference of equal to or greater than 20° C. between a precipitation temperature of an α-Fe crystal phase and a precipitation temperature of an Fe compound,

the Fe-based soft magnetic alloy is formed of a mixed-phase structure in which an amorphous phase and the α-Fe crystal phase are mixed,

a diameter of a crystallite of the α-Fe crystal phase is equal to or smaller than 50 nm, and a volume fraction of the α-Fe crystal phase to a total is equal to or smaller than 40%,

a composition formula is represented by Fe 100 −x −u J x R u ,

a component J is at least one element selected from the group consisting of Cr, Co, Ni, and Nb, and

x and u representing composition ratios satisfy: 0 at %≦x≦6 at %, 17 at %≦u≦25 at %, and 17 at %≦x+u≦27.1 at %.

2. The Fe-based soft magnetic alloy according to claim 1 , wherein the composition formula is represented by Fe 100 −x −y −z −w −t J x P y C z B w Si t , and v, z, w, and t representing composition ratios satisfy: 0 at %≦y≦11 at %, 0 at %≦z≦4.2 at %, 5.7 at %≦w≦17 at %, 0 at %≦t≦11 at %, and 17 at %≦x+y+z+w+t≦27.1 at %.

3. The Fe-based soft magnetic alloy according to claim 2 , wherein the Fe-based soft magnetic alloy consists of:

Fe;

a component M which is at least one element selected from the group consisting of Cr, Co, and Ni; and

P, C, B, and Si,

the composition formula is represented by Fe 100 −x −y −z −w −t M x P y C z B w Si t , and

x, y, z, w, and t representing composition ratios satisfy: 0 at %≦x≦6 at %, 0.3 at %≦y≦8.3 at %, 2.15 at %≦z≦4.2 at %, 5.7 at %≦w≦16.7 at %, 1.9 at %≦t≦8.9 at %, and 72.9 at %≦100−x−y−z−w−t ≦79.4 at %.

4. The Fe-based soft magnetic alloy according to claim 3 , wherein y, w, and t representing composition ratios satisfy:

0.3 at %≦y≦8.3 at %, 6.7 at %≦w≦11.7 at %, and 1.9 at %≦t≦5.9 at %.

5. The Fe-based soft magnetic alloy according to claim 2 ,

wherein the composition formula is represented by Fe 100 −w −t −b B w Si t Cr b , and

w, t, and b representing composition ratios satisfy:

11 at %≦w≦17 at %, 0 at %≦t≦10 at %, 0 at %≦b≦1 at %, and 75 at %≦100−w−t−b≦83 at %.

6. The Fe-based soft magnetic alloy according to claim 2 , wherein the Fe-based soft magnetic alloy consists of includes:

Fe;

a component L which is at least one element selected from the group consisting of Nb and Cr; and

P and B,

the composition formula is represented by Fe 100 −y −w −a P y B w L a ,and

y, w, and a representing composition ratios satisfy: 6 at %≦y≦11 at %, 8 at %≦w≦14 at %, 2 at %≦a≦3 at %, and 77 at %≦100−y−w−a≦80 at %.

7. A dust core comprising:

powder of the Fe-based soft magnetic alloy according to claim 1 ; and

a binding material solidifying the powder.

8. A dust core comprising:

powder of an Fe-based soft magnetic alloy; and

a binding material solidifying the powder,

wherein the Fe-based soft magnetic alloy consists of:

Fe; and

a component R,

wherein the component R is at least one element selected from the group consisting of P, C, B, and Si,

there is a temperature difference of equal to or greater than 20° C. between a precipitation temperature of an α-Fe crystal phase and a precipitation temperature of an Fe compound,

the Fe-based soft magnetic alloy is formed of a mixed-phase structure in which an amorphous phase and the α-Fe crystal phase are mixed, and

a diameter of a crystallite of the α-Fe crystal phase is equal to or smaller than 50 nm, and a volume fraction of the α-Fe crystal phase to a total is equal to or lower than 40%.

9. The Fe-based soft magnetic alloy according to claim 1 , wherein the volume fraction of the α-Fe crystal phase to the total is equal to or smaller than 20%.

10. The Fe-based soft magnetic alloy according to claim 1 , wherein the volume fraction of the α-Fe crystal phase to the total is equal to or smaller than 15%.

11. The Fe-based soft magnetic alloy according to claim 1 , wherein the volume fraction of the α-Fe crystal phase to the total is equal to or smaller than 10%.

12. The dust core according to claim 8 , wherein the volume fraction of the α-Fe crystal phase to the total is equal to or smaller than 20%.

13. The dust core according to claim 8 , wherein the volume fraction of the α-Fe crystal phase to the total is equal to or smaller than 15%.

14. The dust core according to claim 8 , wherein the volume fraction of the α-Fe crystal phase to the total is equal to or smaller than 10%.