Fe-based shape memory alloy and its production method

• US 8,815,027 B2
• Filed: 10/06/2010
• Issued: 08/26/2014
• Est. Priority Date: 10/14/2009
• Status: Active Grant

• Current Assignee: Japan Science & Technology Trading Co. Limited
• Original Assignee: Japan Science & Technology Trading Co. Limited
• Inventors: Ishida, Kiyohito, Kainuma, Ryosuke, Ohnuma, Ikuo, Omori, Toshihiro, Ando, Keisuke
• Primary Examiner(s): WYSZOMIERSKI, GEORGE P
• Application Number:
  US13/501,839
• Publication Number:
  US 20120199253A1
• Time in Patent Office: 1,420 Days
• Field of Search: None
• US Class Current: 148/402
• CPC Class Codes: C21D 1/26 Methods of annealing
• CPC Class Codes: C21D 2201/01 Shape memory effect
• CPC Class Codes: C21D 2211/004 Dispersions; Precipitations
• CPC Class Codes: C21D 2211/008 Martensite
• CPC Class Codes: C21D 6/001 containing Ni C21D6/004 takes precedence
• CPC Class Codes: C21D 6/005 containing Mn
• CPC Class Codes: C22C 22/00 Alloys based on manganese
• CPC Class Codes: C22C 30/00 Alloys containing less than 50% by weight of each constituent
• CPC Class Codes: C22C 30/02 containing copper
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/06 containing aluminium
• CPC Class Codes: C22C 38/08 containing nickel C22C38/105 takes precedence

Abstract

An Fe-based shape memory alloy comprising 25-42 atomic % of Mn, 12-18 atomic % of Al, and 5-12 atomic % of Ni, the balance being Fe and inevitable impurities, and an Fe-based shape memory alloy comprising 25-42 atomic % of Mn, 12-18 atomic % of Al, and 5-12 atomic % of Ni, as well as 15 atomic % or less in total of at least one selected from the group consisting of 0.1-5 atomic % of Si, 0.1-5 atomic % of Ti, 0.1-5 atomic % of V, 0.1-5 atomic % of Cr, 0.1-5 atomic % of Co, 0.1-5 atomic % of Cu, 0.1-5 atomic % of Mo, 0.1-5 atomic % of W, 0.001-1 atomic % of B and 0.001-1 atomic % of C, the balance being Fe and inevitable impurities.

Claims

1. An Fe-based shape memory alloy comprising 25-42 atomic % of Mn, 12-18 atomic % of Al, and 5-12 atomic % of Ni, the balance being Fe and inevitable impurities.

2. The Fe-based shape memory alloy according to claim 1, wherein its matrix has a bcc crystal structure.

3. The Fe-based shape memory alloy according to claim 2, wherein a phase having a B2 structure is precipitated in a matrix having an A2 structure.

4. The Fe-based shape memory alloy according to claim 1, wherein its matrix is ferromagnetic.

5. The Fe-based shape memory alloy according to claim 1, comprising a martensite phase and a matrix, wherein the intensity of magnetization is lower in the martensite phase than in the matrix.

6. The Fe-based shape memory alloy according to claim 1, wherein the intensity of magnetization changes reversibly in response to an amount of strain applied.

7. A method for producing the Fe-based shape memory alloy recited in claim 1, comprising a solution treatment step at 1100-1300°

C.

8. The method for producing an Fe-based shape memory alloy according to claim 7, comprising an aging treatment step at 100-350°

C. after the solution treatment step.

9. A wire formed by the Fe-based shape memory alloy recited in claim 1, wherein said Fe-based shape memory alloy has an average crystal grain size equal to or more than the radius of said wire.

10. A plate formed by the Fe-based shape memory alloy recited in claim 1, said Fe-based shape memory alloy having an average crystal grain size equal to or more than the thickness of said plate.

11. An Fe-based shape memory alloy comprising 25-42 atomic % of Mn, 12-18 atomic % of Al, and 5-12 atomic % of Ni, as well as 15 atomic % or less in total of at least one selected from the group consisting of 0.1-5 atomic % of Si, 0.1-5 atomic % of Ti, 0.1-5 atomic % of V, 0.1-5 atomic % of Cr, 0.1-5 atomic % of Co, 0.1-5 atomic % of Cu, 0.1-5 atomic % of Mo, 0.1-5 atomic % of W, 0.001-1 atomic % of B and 0.001-1 atomic % of C, the balance being Fe and inevitable impurities.

12. The Fe-based shape memory alloy according to claim 11, wherein its matrix has a bcc crystal structure.

13. The Fe-based shape memory alloy according to claim 12, wherein a phase having a B2 structure is precipitated in a matrix having an A2 structure.

14. The Fe-based shape memory alloy according to claim 11, wherein its matrix is ferromagnetic.

15. The Fe-based shape memory alloy according to claim 11, comprising a martensite phase and a matrix, wherein the intensity of magnetization is lower in the martensite phase than in the matrix.

16. The Fe-based shape memory alloy according to claim 11, wherein the intensity of magnetization changes reversibly in response to an amount of strain applied.

17. A method for producing the Fe-based shape memory alloy recited in claim 11, comprising a solution treatment step at 1100-1300°

C.

18. The method for producing an Fe-based shape memory alloy according to claim 17, comprising an aging treatment step at 100-350°

C. after the solution treatment step.

19. A wire formed by the Fe-based shape memory alloy recited in claim 11, wherein said Fe-based shape memory alloy has an average crystal grain size equal to or more than the radius of said wire.

20. A plate formed by the Fe-based shape memory alloy recited in claim 11, said Fe-based shape memory alloy having an average crystal grain size equal to or more than the thickness of said plate.