Ni—Ti-based alloy material, method for producing Ni—Ti-based alloy material, and wire or tube including Ni—Ti-based alloy material

Patent metadata

Field	Value
Publication number	US-12065719-B2
Application number	US-202017614486-A
Country	US
Kind code	B2
Filing date	Apr 30, 2020
Priority date	May 29, 2019
Publication date	Aug 20, 2024
Grant date	Aug 20, 2024

Abstract

A Ni—Ti-based alloy material includes a matrix phase consisting essentially of a Ni—Ti-based alloy and having a B2 type crystal structure. A nonmetallic inclusion is present in the matrix phase, in which 99% by mass or more of the nonmetallic inclusion is a TiC-based inclusion having a NaCl type crystal structure, the TiC-based inclusion has a lattice misfit (δ) in a range of 0.4238 or more and 0.4259 or less. The lattice misfit (δ) is represented by Expression δ=(a1−a2)/a2, where a1 is a lattice constant (Å) of the TiC-based inclusion and a2 is a lattice constant (Å) of the matrix phase.

First claim

The invention claimed is:

1. A Ni—Ti-based alloy material comprising:
a matrix phase consisting essentially of a Ni—Ti-based alloy and having a B2 crystal structure; and
a nonmetallic inclusion present in the matrix phase, wherein
99% by mass or more of a totality of nonmetallic inclusions is a TIC inclusion having a NaCl crystal structure,
the TiC inclusion has a lattice misfit (δ) in a range of 0.4238 or more and 0.4259 or less, the lattice misfit (δ) being represented by Expression (1) below,

δ
=

(

a
⁢

⁢
1

-

a
⁢

⁢
2

)

/
a

⁢

⁢
2

Expression
⁢

⁢

(
1
)

a1 is a lattice constant (Å) of the TiC inclusion and a2 is a lattice constant (Å) of the matrix phase,
the Ni—Ti-based alloy is free of Ti 4 Ni 2 O x , and
the Ni—Ti-based alloy material has a ratio ([C]/[O] ratio) of a carbon concentration ([C]) to an oxygen concentration ([O]) in a range of 0.8 or more and less than 1.4.

2. The Ni—Ti-based alloy material according to claim 1 , the Ni—Ti-based alloy material comprises 54.5% by mass or more and 57.0% by mass or less of Ni, 0.04% by mass or less of C, and 0.04% by mass or less of O, with a balance being Ti and unavoidable impurities.

3. The Ni—Ti-based alloy material according to claim 2 , the Ni—Ti-based alloy material has superelasticity.

4. The Ni—Ti-based alloy material according to claim 1 , the Ni—Ti-based alloy material has superelasticity.

5. The Ni—Ti-based alloy material according to claim 1 , wherein 100% by mass of a totality of nonmetallic inclusions is the TIC inclusion.

6. The Ni—Ti-based alloy material according to claim 5 , the Ni—Ti-based alloy material comprises 54.5% by mass or more and 57 . 0 % by mass or less of Ni, 0.04% by mass or less of C, and 0.04% by mass or less of O, with a balance being Ti and unavoidable impurities.

7. The Ni—Ti-based alloy material according to claim 6 , the Ni—Ti-based alloy material has superelasticity.

8. The Ni—Ti-based alloy material according to claim 5 , the Ni—Ti-based alloy material has superelasticity.

9. A wire or a tube comprising the Ni—Ti-based alloy material according to claim 1 .

10. A wire or a tube comprising the Ni—Ti-based alloy material according to claim 2 .

11. A tube for a stent or for an artificial heart valve, the tube being formed of the Ni—Ti-based alloy material according to claim 4 .

12. A wire for a guidewire, the wire being formed of the Ni—Ti-based alloy material according to claim 4 .

13. A method for producing the Ni—Ti-based alloy material according to claim 1 , the method comprising:
sequentially subjecting a Ni—Ti-based alloy raw material to at least a melting/casting step (step ), a hot working step (step 2), a cold working step (step 3), an annealing step (step 4), and a superelasticity-imparting heat treatment step (step 5), wherein
a Ni—Ti-based alloy ingot obtained in the melting/casting step (step 1) has a carbon concentration ([C]) of 0.04% by mass or less, an oxygen concentration ([O]) of 0.04% by mass or less, and a ratio ([C]/[O] ratio) of the carbon concentration ([C]) to the oxygen concentration ([O]) of 0.5 or more, and
the Ni—Ti-based alloy raw material is heated at a temperature of 500° ° C. or more and 800° C. or less in the hot working step (step 2).

14. A method for producing the Ni—Ti-based alloy material according to claim 5 , the method comprising:
sequentially subjecting a Ni—Ti-based alloy raw material to at least a melting/casting step (step 1), a hot working step (step 2), a cold working step (step 3), an annealing step (step 4), and a superelasticity-imparting heat treatment step (step 5), wherein
a Ni—Ti-based alloy ingot obtained in the melting/casting step (step 1) has a carbon concentration ([C]) of 0.04% by mass or less, an oxygen concentration ([O]) of 0.04% by mass or less, and a ratio ([C]/[O] ratio) of the carbon concentration ([C]) to the oxygen concentration ([O]) of 0.5 or more, and
the Ni—Ti-based alloy raw material is heated at a temperature of 500° C. or more and 800° C. or less in the hot working step (step 2).

Assignees

• Furukawa Techno Mat Co Ltd
• Furukawa Electric Co Ltd

Inventors

• Yamashita Fumiyoshi
• Kise Sumio
• URUMA Kenji

Classifications

• C21D8/10

  during manufacturing of tubular bodies · CPC title

• C21D8/06

  during manufacturing of rods or wires · CPC title

• C22F1/00

  Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working (apparatus for mechanical working of metal B21, B23, B24) · CPC title

• C22F1/10

  of nickel or cobalt or alloys based thereon · CPC title

• B22D21/06

  Casting non-ferrous metals with a high melting point, e.g. metallic carbides (B22D21/02 takes precedence) · CPC title