Continuous Shape Memory Alloy Wire Production by Melt Spinning

Patent metadata

Field	Value
Publication number	US-2020024715-A1
Application number	US-201816202575-A
Country	US
Kind code	A1
Filing date	Nov 28, 2018
Priority date	May 6, 2014
Publication date	Jan 23, 2020
Grant date	—

Abstract

In a method for forming a shape memory alloy wire a shape memory alloy composition of CuAlMnNi excluding grain refiner elements, is mixed, including between about 20 at % and about 28 at % Al, between about 2 at % and about 4 at % Ni, between about 3 at % and about 5 at % Mn, and Cu as a remaining balance. The mixture is heated between about 1100° C. and about 1400° C. and ejected from a crucible, at an ejection pressure of between about 3 bar and about 5 bar through a nozzle having a nozzle diameter of between about 200 microns and about 280 microns, to a face of a melt spinning wheel with speed of between about 9 m/s and about 13 m/s until there is formed a shape memory alloy wire having a length of at least about 1.5 meters and a diameter of no more than about 150 microns.

First claim

We claim:

1 . A method for forming a shape memory alloy wire comprising:
mixing a shape memory alloy composition of CuAlMnNi and excluding grain refiner elements, said shape memory alloy composition including between about 20 at % and about 28 at % Al, between about 2 at % and about 4 at % Ni, between about 3 at % and about 5 at % Mn, and Cu as a remaining balance of the shape memory alloy composition, to obtain a resulting mixture; heating the mixture in a crucible until the mixture is a melted shape memory alloy at a temperature of between about 1100° C. and about 1400° C.; and ejecting the melted shape memory alloy from the crucible, at an ejection pressure of between about 3 bar and about 5 bar, through a nozzle in the crucible having a nozzle diameter of between about 200 microns and about 280 microns, to a face of a melt spinning wheel that is controlled to have a wheel speed of between about 9 m/s and about 13 m/s, with ejection of the melted shape memory alloy continuing until there is formed at the melt spinning wheel a shape memory alloy wire having a length of at least about 1.5 meters and a diameter of no more than about 150 microns.

2 . The method of claim 1 wherein during ejecting the melted shape memory alloy from the crucible, the wheel speed of the melt spinning wheel is controlled to between about 10 m/s and about 10.25 m/s.

3 . The method of claim 1 wherein the melted shape memory alloy is ejected from the crucible to a pressure of about 4 bar.

4 . The method of claim 1 wherein the melted shape memory alloy is ejected from the crucible through a nozzle in the crucible having a nozzle diameter of between about 200 microns and about 250 microns.

5 . The method of claim 1 wherein the melted shape memory alloy is at a temperature of between about 1200° C. and about 1300° C.

6 . The method of claim 1 wherein during ejecting the melted shape memory alloy from the crucible, the wheel speed of the melt spinning wheel is maintained at that wheel speed, between about 9 m/s and about 13 m/s, which matches a wire casting rate at which shape memory alloy wire is formed for a melted shape memory alloy temperature of between about 1100° C. and about 1400° C., an ejection pressure of between about 3 bar and about 5 bar, and a nozzle diameter of between about 200 microns and about 280 microns.

7 . The method of claim 1 wherein during ejecting the melted shape memory alloy from the crucible, the wheel speed of the melt spinning wheel is maintained at that wheel speed, between about 9 m/s and about 13 m/s, which matches a wire casting rate at which shape memory alloy wire is formed at a melted shape memory alloy temperature of between about 1200° C. and about 1300° C., an ejection pressure of about 4 bar, and a nozzle diameter of between about 200 microns and about 250 microns.

8 . The method of claim 1 wherein the melted alloy shape memory alloy is ejected from the crucible at an ejection pressure of about 4 bar through a nozzle of no more than about 250 microns in diameter at an ejection temperature of about 1300° C. toward a melt spinning wheel having a wheel speed of between about 10 m/s and about 10.25 m/s.

9 . The method of claim 1 further comprising:
heating the formed shape memory alloy wire at a heating temperature of between about 800° C. and 900° C. for a duration of between about 2 hours and about 3 hours in an atmosphere of inert gas.

10 . The method of claim 1 further comprising:
heating the formed shape memory ally wire at a heating temperature of about 800° C. for a duration of about 3 hours in an atmosphere of inert gas

11 . The method of claim 1 wherein said shape memory alloy composition of CuAlMnNi includes between about 22 at % and about 24 at % Al, between about 3.5 at % and about 3.7 at % Ni, between about 4 at % and about 4.5 at % Mn, and Cu as a remaining balance of said composition.

12 . The method of claim 1 wherein said shape memory alloy composition of CuAlMnNi includes about 22.3 at % Al, about 3.6 at % Ni, about 4.4 at % Mn, and about 3.6 at % Ni.

13 . The method of claim 1 wherein said shape memory alloy composition of CuAlMnNi includes no more than about 30% of Al, Mn, and Ni.

14 . The method of claim 1 wherein ejecting the melted shape memory alloy from the crucible toward a face of a melt spinning wheel comprises ejecting the melted shape memory alloy into a quenching medium disposed at the melt spinning wheel face.

15 . The method of claim 1 wherein ejecting the melted shape memory alloy from the crucible toward a face of a melt spinning wheel comprises ejecting the melted shape memory alloy into a quenching medium, selected from liquid media and gaseous media, that is disposed at the melt spinning wheel face.

16 . The method of claim 1 wherein ejecting the melted shape memory alloy from the crucible toward a face of a melt spinning wheel comprises ejecting the melted shape memory alloy into a quenching medium, selected from air, helium, and an inert gas, that is disposed at the melt spinning wheel face.

17 . The method of claim 1 wherein ejecting the melted shape memory alloy from the crucible toward a face of a melt spinning wheel comprises ejecting the melted shape memory alloy into a quenching medium, selected from water and an oil, that is disposed at the melt spinning wheel face.

18 . The method of claim 14 further comprising:
controlling temperature of the quenching medium to a temperature between about −20° C. and about 80° C.

Assignees

• Massachusetts Inst Technology

Inventors

• Tuncer Nihan
• Schuh Christopher A

Classifications

• C22C9/01

  with aluminium as the next major constituent · CPC title

• B22D11/005

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

• C22F1/08 Primary

  of copper or alloys based thereon · CPC title

• Y10T428/12

  All metal or with adjacent metals · CPC title

• C22F1/006

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