TOUGH IRON-BASED BULK METALLIC GLASS ALLOYS

• US 20120073710A1
• Filed: 09/27/2011
• Published: 03/29/2012
• Est. Priority Date: 05/19/2009
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Demetriou, Marios D., Johnson, William L., Kim, Samuel T.
• Granted Patent: US 8,911,572 B2
• Time in Patent Office: Days
• US Class Current: 148/548
• CPC Class Codes: C22C 38/00 Ferrous alloys, e.g. steel alloys cast-iron alloys C22C37/00
• CPC Class Codes: C22C 38/002 containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• CPC Class Codes: C22C 38/08 containing nickel C22C38/105 takes precedence
• CPC Class Codes: C22C 38/10 containing cobalt
• CPC Class Codes: C22C 38/12 containing tungsten, tantalum, molybdenum, vanadium, or niobium
• CPC Class Codes: C22C 45/02 with iron as the major constituent

Abstract

A family of iron-based, phosphor-containing bulk metallic glasses having excellent processability and toughness, methods for forming such alloys, and processes for manufacturing articles therefrom are provided. The inventive iron-based alloy is based on the observation that by very tightly controlling the composition of the metalloid moiety of the Fe-based, P-containing bulk metallic glass alloys it is possible to obtain highly processable alloys with surprisingly low shear modulus and high toughness. Further, by incorporating small fractions of silicon (Si) and cobalt (Co) into the Fe—Ni—Mo—P—C—B system, alloys of 3 and 4 mm have been synthesized with high saturation magnetization and low switching losses.

Claims

1. A ferromagnetic Fe-based metallic glass composition comprising at least Fe, P, C and B, where Fe comprises an atomic percent of at least 60, P comprises an atomic percent of from 5 to 17.5, C comprises an atomic percent of from 3 to 6.5, and B comprises an atomic percent of from 1 to 3.5;

further comprising at least Mo and Ni, and optionally Co and Si; and

wherein the concentrations of Mo and Ni vary in accordance with the concentration of Co and Si as follows;

where Si comprises an atomic percent of from 0 to 0.5 and Co comprises an atomic percent of from 0 to 6, then Mo comprises an atomic percent of from 4.5 to 5.5, and Ni comprises an atomic percent in accordance with the equation;

m−

k·

z, where m is a constant ranging from 4 to 6, k is a constant ranging from 0.5 to 1, and z represents the atomic percent of Co, and

where Si comprises an atomic percent of from 0.5 to 1.5 and Co comprises an atomic percent of from 0 to 6, then Mo comprises an atomic percent of from 3.5 to 4.5 and Ni comprises an atomic percent of from 2.5 to 4.5.

2. The metallic glass of claim 1, wherein the atomic percent of P is from 10 to 13.

3. The metallic glass of claim 1, wherein the atomic percent of P is about 12.5.

4. The metallic glass of claim 1, wherein the atomic percent of C is from 4.5 to 5.5.

5. The metallic glass of claim 1, wherein the atomic percent of C is about 5.

6. The metallic glass of claim 1, wherein the atomic percent of B is from 2 to 3.

7. The metallic glass of claim 1, wherein the atomic percent of B is about 2.5

8. The metallic glass of claim 1, wherein where Si comprises an atomic percent of from 0 to 0.5 and Co comprises an atomic percent of from 0 to 5, then Mo comprises an atomic percent of about 5 and Ni comprises an atomic percent ranging from about 2 to about 5.

9. The metallic glass of claim 1, wherein where Si comprises an atomic percent of from 0.5 to 1.5 and Co comprises an atomic percent of from 0 to 5, then Mo comprises an atomic percent of about 4 and Ni comprises an atomic percent of about 3.

10. The metallic glass of claim 1, wherein the as-cast alloy at room temperature has a magnetization (M_s) of at least 1.0 T.

11. The metallic glass of claim 1, wherein the as-cast alloy at room temperature has a coercivity (H_c) of less than 210 A/m, when measured on a disk sample 3 mm diameter and 1 mm in height using a vibrating sample magnetometer.

12. The metallic glass of claim 1, wherein the as-cast alloy at room temperature has a retentivity (M_r) of less than 110×

10<sup>−

5</sup> T, when measured on a disk sample 3 mm diameter and 1 mm in height using a vibrating sample magnetometer

13. The metallic glass of claim 1, wherein the composition further comprises Ru in an atomic percent of from 1 to 5.

14. The metallic glass of claim 1, further comprising at least one trace element wherein the total weight fraction of said at least one trace element is less than 0.02.

15. The metallic glass of claim 1, wherein the alloy has a glass transition temperature (T_g) of less than 440°

C.

16. The metallic glass of claim 1, wherein the alloy has a shear modulus (G) of less than 60 GPa.

17. The metallic glass of claim 1, wherein the alloy has a critical rod diameter of at least 3 mm.

18. The metallic glass alloy of claim 1, wherein the composition is selected from the group consisting of Fe₇₀Ni₅Mo₅P_12.5C₅B_2.5, Fe₆₉Ni₄Co₂Mo₅P_12.5C₅B_2.5, Fe₇₀Ni₃Co₂Mo₅P_12.5C₅B_2.5, Fe₆₉Ni₃Co₃Mo₅P_12.5C₅B_2.5, Fe_68.5Ni_2.5Co₄Mo₅P_12.5C₅B_2.5, Fe₆₈Ni₂Co₅Mo₅P_12.5C₅B_2.5, Fe₇₂Ni₄Mo₄P_11.5C₅B_2.5Si₁, Fe₇₃Ni₃Mo₄P_11.5C₅B_2.5Si₁, Fe₇₁Ni₃Co₂Mo₄P_11.5C₅B_2.5Si₁, Fe₇₀Ni₃Co₃Mo₄P_11.5C₅B_2.5Si₁, Fe₆₉Ni₃Co₄Mo₄P_11.5C₅B_2.5Si₁, and Fe₆₈Ni₃Co₅Mo₄P_11.5C₅B_2.5Si₁ where numbers denote atomic percent.

19. A method of manufacturing a metallic glass composition comprising:

providing a feedstock material comprising at least Fe, P, C and B, where Fe comprises an atomic percent of at least 60, P comprises an atomic percent of from 5 to 17.5, C comprises an atomic percent of from 3 to 6.5, and B comprises an atomic percent of from 1 to 3.5;

further comprising at least Mo and Ni, and optionally Co and Si; and

wherein the concentrations of Mo and Ni vary in accordance with the concentration of Co and Si as follows;

where Si comprises an atomic percent of from 0 to 0.5 and Co comprises an atomic percent of from 0 to 6, then Mo comprises an atomic percent of from 4.5 to 5.5, and Ni comprises an atomic percent in accordance with the equation;

m−

k·

z, where m is a constant ranging from 4 to 6, k is a constant ranging from 0.5 to 1, and z represents the atomic percent of Co, and

where Si comprises an atomic percent of from 0.5 to 1.5 and Co comprises an atomic percent of from 0 to 6, then Mo comprises an atomic percent of from 3.5 to 4.5 and Ni comprises an atomic percent of from 2.5 to 4.5; and

melting said feedstock into a molten state; and

quenching said molten feedstock at a cooling rate sufficiently rapid to prevent crystallization of said alloy.

20. The method of claim 19, wherein if the composition contains Si, the molten alloy is fluxed prior to quenching.

21. The method of claim 20, wherein the flux is boron oxide.

22. The method of claim 19, further comprising annealing the metallic glass after quenching.

23. A magnetic metallic glass object comprising:

a body formed of a metallic glass alloy comprising at least Fe, P, C and B, where Fe comprises an atomic percent of at least 60, P comprises an atomic percent of from 5 to 17.5, C comprises an atomic percent of from 3 to 6.5, and B comprises an atomic percent of from 1 to 3.5;

further comprising at least Mo and Ni, and optionally Co and Si; and

wherein the concentrations of Mo and Ni vary in accordance with the concentration of Co and Si as follows;

where Si comprises an atomic percent of from 0 to 0.5 and Co comprises an atomic percent of from 0 to 6, then Mo comprises an atomic percent of from 4.5 to 5.5, and Ni comprises an atomic percent in accordance with the equation;

m−

k·

z, where m is a constant ranging from 4 to 6, k is a constant ranging from 0.5 to 1, and z represents the atomic percent of Co, and

where Si comprises an atomic percent of from 0.5 to 1.5 and Co comprises an atomic percent of from 0 to 6, then Mo comprises an atomic percent of from 3.5 to 4.5 and Ni comprises an atomic percent of from 2.5 to 4.5.

24. The object of claim 23, wherein the object is a magnetic core used in the generation or conversion of electrical power.

25. The object of claim 24, wherein the magnetic core has a planar shape, a torroidal shape, a ring shape, a U shape, a C shape, an I shape, an E shape, or any combination of the above shapes.

26. The object of claim 24, wherein the magnetic core is an assembly of more than one component, and wherein each component has a cross section thickness of not less than 0.5 mm.

27. The object of claim 24, wherein the magnetic core is monolithic.

28. The object of claim 23, wherein the magnetic object has an application selected from the group consisting of inductors, transformers, clutches, and DC/AC converters.