Continuous oligocrystalline shape memory alloy wire produced by melt spinning

Patent metadata

Field	Value
Publication number	US-10167540-B2
Application number	US-201514705247-A
Country	US
Kind code	B2
Filing date	May 6, 2015
Priority date	May 6, 2014
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

There is provided herein a shape memory alloy wire that includes an alloy composition of CuAlMnNi and excluding grain refiner elements. The alloy composition includes 20 at %-28 at % Al, 2 at %-4 at % Ni, 3 at %-5 at % Mn with Cu as a remaining balance of the alloy composition. The alloy composition is disposed as an elongated wire of at least about 1 meter in length, having a wire diameter of less than about 150 microns. At least about 50 vol % of said alloy composition along said wire length has an oligocrystalline microstructure as-disposed in the wire and without thermal treatment of the wire.

First claim

We claim:

1. A shape memory alloy wire comprising:
an alloy composition comprising CuAlMnNi and excluding grain refiner elements, said alloy composition including 20 at %-28 at % Al, 2 at %-4 at % Ni, 3 at %-5 at % Mn with Cu as a remaining balance of the alloy composition;
said alloy composition being disposed as an elongated wire of at least about 1.5 meters in length, having a wire diameter of less than about 150 microns; and
at least about 50 vol % of said alloy composition along said wire length having an oligocrystalline microstructure as-disposed in the wire and without thermal treatment of the wire.

2. The shape memory alloy wire of claim 1 wherein at least about 75 vol % of said alloy composition along said wire length is oligocrystalline.

3. The shape memory alloy wire of claim 1 wherein at least about 90 vol % of said alloy composition along said wire length is oligocrystalline.

4. The shape memory alloy wire of claim 1 wherein the wire exhibits a strain recovery of at least about 8% at room temperature.

5. The shape memory alloy wire of claim 1 wherein the wire exhibits a strain recovery of at least about 10% at room temperature.

6. The shape memory alloy wire of claim 1 wherein said alloy composition includes 22 at %-24 at % Al, 3.5 at %-3.7 at % Ni, 4 at %-4.5 at % Mn, and with Cu as a remaining balance of the composition.

7. The shape memory alloy wire of claim 1 wherein said alloy composition includes 22.3 at % Al, 4.4 at % Mn and 3.6 at % Ni.

8. The shape memory alloy wire of claim 1 wherein the diameter of the wire is no more than about 100 microns.

9. The shape memory alloy wire of claim 1 wherein the diameter of the wire is less than about 120 microns.

10. The shape memory alloy wire of claim 1 wherein the wire diameter has a diameter uniformity of ±5 microns along a 1 meter length of the wire.

11. The shape memory alloy wire of claim 1 wherein the wire has an atomic place spacing difference of between 0.007 nm and 0.008 nm.

12. The shape memory alloy wire of claim 1 wherein no more than about 30% of the alloy composition consists of Al, Mn, and Ni.

13. The shape memory alloy wire of claim 1 wherein the wire exhibits a strain recovery that is at least as large as a strain recovery that is exhibited by a monocrystalline wire having a composition including 20 at %-28 at % Al, 2 at %-4 at % Ni, 3 at %-0.5 at % Mn with Cu as a remaining balance of the alloy, and having a monocrystalline length of about 1 meter in length and a monocrystalline wire diameter of less than about 150 microns.

14. A shape memory alloy wire comprising:
an alloy composition comprising CuAlMnNi and excluding grain refiner elements, said alloy composition including 20 at %-28 at % Al, 2 at %-4 at % Ni, 3 at %-5 at % Mn with Cu as a remaining balance of the alloy composition;
said alloy composition being disposed as an elongated wire of at least about 1.5 meters in length, having a wire diameter of at least about 150 microns; and
at least about 50 vol % of said alloy composition along said wire length having an oligocrystalline microstructure.

Assignees

• Massachusetts Inst Technology

Inventors

• Tuncer Nihan
• Schuh Christopher A

Classifications

• C22F1/08 Primary

  of copper or alloys based thereon · CPC title

• Y10T428/12

  All metal or with adjacent metals · CPC title

• C22C9/01

  with aluminium as the next major constituent · CPC title

• B22D11/005

  of wire (casting on wire B22D19/14) · CPC title

• C22F1/006

  Resulting in heat recoverable alloys with a memory effect · CPC title