Bulk ferromagnetic glasses free of non-ferrous transition metals

Patent metadata

Field	Value
Publication number	US-9777359-B2
Application number	US-201414272136-A
Country	US
Kind code	B2
Filing date	May 7, 2014
Priority date	May 7, 2013
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

Ferrous metal alloys including Fe, Co and optionally Ni with metalloids Si, B and P are provided that are substantially close to the peak in glass forming ability and have a combination of both good glass formability and good ferromagnetic properties. In particular, Fe/Co-based compositions wherein the Co content is between 15 and 30 atomic percent and the metalloid content is between 22 and 24 atomic percent at a well-defined metalloid moiety, have been shown to be capable of forming bulk glassy rods with diameters as large as 4 mm or larger. In addition, incorporating a small content of Ni under 10 atomic percent and additions of Mo, Cr, Nb, Ge, or C at an incidental impurity level of up to 2 atomic percent are not expected to impair the bulk-glass-forming ability of the present alloys.

First claim

What is claimed is:

1. An Fe-bearing alloy, consisting of Co with an atomic fraction denoted by a, Ni with an atomic fraction denoted by b, Si with an atomic fraction denoted by c, B with an atomic fraction denoted by d, P with an atomic fraction denoted by d;
where a is between 2 and 60, b is up to 10, c ranges from 4 to less than 9, d ranges from 3 to less than 10, e ranges from more than 5 to 15, and where the balance is Fe and incidental impurities; and
wherein the critical rod diameter of the Fe-bearing alloy is at least 1 mm.

2. The alloy of claim 1 , wherein a is between 5 and 40, b is 0, c is between 5 and 8.5, d is between 4 and 9, e is between 6 and 13, and wherein the critical rod diameter is at least 2 mm.

3. The alloy of claim 1 , wherein a is between 10 and 30, b is 0, c is between 6 and 8.5, d is between 5 and 8, e is between 7 and 12, and wherein the critical rod diameter is at least 2.5 mm.

4. The alloy of claim 1 , wherein a is between 12 and 25, b is 0, c is between 6.5 and 8, d is between 5.5 and 7.5, e is between 8 and 11, and wherein the critical rod diameter is at least 3 mm.

5. The alloy of claim 1 , wherein the sum of c, d, and e is between 21 and 25.

6. The alloy of claim 1 , wherein a is between 5 and 40, b is 0, the sum of c, d, and e is between 22 and 24, and wherein the critical rod diameter is at least 2 mm.

7. The alloy of claim 1 , wherein a is between 10 and 30, b is 0, the sum of c, d, and e is between 22.5 and 23.5, and wherein the critical rod diameter is at least 2.5 mm.

8. The alloy of claim 1 , wherein the ratio of the atomic fraction of Co to the atomic fraction Fe is between 0.2 and 0.4.

9. The alloy of claim 1 , wherein the solidus and liquidus temperatures of the alloy are within 100° C. apart when evaluated by a calorimetry scan rate of 20 K/min, and wherein the critical rod diameter is at least 1 mm.

10. The alloy of claim 1 , wherein the solidus and liquidus temperatures of the alloy are within 80° C. apart when evaluated by a calorimetry scan rate of 20 K/min, and wherein the critical rod diameter is at least 2 mm.

11. The alloy of claim 1 , wherein the solidus and liquidus temperatures of the alloy are within 60° C. apart when evaluated by a calorimetry scan rate of 20 K/min, and wherein the critical rod diameter is at least 2.5 mm.

12. The alloy of claim 1 , wherein the solidus and liquidus temperatures of the alloy are within 50° C. apart when evaluated by a calorimetry scan rate of 20 K/min, and wherein the critical rod diameter is at least 3 mm.

13. The alloy of claim 1 , wherein the incidental impurities may contain up to 2 atomic percent of any element selected from the group consisting of Mo, Cr, Nb, Ge, and C.

14. A metallic glass comprising the alloy of claim 1 .

15. A method for processing an Fe-bearing alloy to form a metallic glass, the method comprising:
melting an Fe-bearing alloy consisting of, Co with an atomic fraction denoted by a, Ni with an atomic fraction denoted by b, Si with an atomic fraction denoted by c, B with an atomic fraction denoted by d, P with an atomic fraction denoted by d;
where a is between 2 and 60, b is up to 10, c ranges from 4 to less than 9, d ranges from 3 to less than 10, e ranges from more than 5 to 15, and where the balance is Fe and incidental impurities;
wherein the critical rod diameter of the Fe-bearing alloy is at least 1 mm; and
quenching the molten alloy at a cooling rate sufficiently rapid to prevent crystallization of the alloy to form the metallic glass.

16. The method of claim 15 , wherein the melt is fluxed with a reducing agent prior to quenching.

17. The method of claim 16 , wherein the reducing agent is boron oxide.

18. The method of claim 16 , wherein the temperature during fluxing is at least 200 degrees above the liquidus temperature of the alloy.

19. The method of claim 15 , wherein the melt temperature prior to quenching to form the amorphous sample is at least 200 degrees above the liquidus temperature of the alloy.

20. The method of claim 15 , wherein the melt temperature prior to quenching to form the amorphous sample is at least 1300° C.

Assignees

• California Inst Of Techn

Inventors

• Liu Xiao
• Demetriou Marios D
• Johnson William L
• Floyd Michael

Classifications

• C22C33/003

  making amorphous alloys · CPC title

• C22C45/02 Primary

  with iron as the major constituent · CPC title

• C21D1/18

  Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62) · CPC title