Method for Controlling the Energy Damping of a Shape Memory Alloy With Surface Roughness

Patent metadata

Field	Value
Publication number	US-2016265089-A1
Application number	US-201315036495-A
Country	US
Kind code	A1
Filing date	Nov 15, 2013
Priority date	Nov 15, 2013
Publication date	Sep 15, 2016
Grant date	—

Abstract

In a method for controlling energy damping in a shape memory alloy, provided is a shape memory alloy having a composition including at least one of: Cu in at least about 10 wt. %, Fe in at least about 5 wt. %, Au in at least about 5 wt. %, Ag in at least about 5 wt. %, Al in at least about 5 wt. %, In in at least about 5 wt. %, Mn in at least about 5 wt. %, Zn in at least about 5 wt. % and Co in at least about 5 wt. %. The shape memory alloy is configured into a structure including a structural feature having a surface roughness and having a feature extent that is greater than about 1 micron and less than about 1 millimeter. Energy damping of the structural feature is modified by exposing the structural feature to process conditions that alter the surface roughness of the structural feature.

First claim

We claim:

1 . A method for controlling energy damping in a shape memory alloy comprising:
providing a shape memory alloy having a composition that includes at least one member selected from the group consisting of Cu in at least about 10 wt. %, Fe in at least about 5 wt. %, Au in at least about 5 wt. %, Ag in at least about 5 wt. %, Al in at least about 5 wt. %, In in at least about 5 wt. %, Mn in at least about 5 wt. %, Zn in at least about 5 wt. % and Co in at least about 5 wt. %; configuring the shape memory alloy into a structure that includes a structural feature having a feature extent that is greater than about 1 micron and less than about 1 millimeter, the shape memory alloy structural feature having a surface roughness; and modifying the energy damping of the shape memory alloy structural feature by exposing the shape memory alloy structural feature to process conditions that alter the surface roughness of the shape memory alloy structural feature.

2 . The method of claim 1 wherein the shape memory alloy structural feature is oligocrystalline.

3 . The method of claim 1 wherein the shape memory alloy structural feature is monocrystalline.

4 . The method of claim 1 wherein the shape memory alloy structural feature has an extent that causes energy dissipation by the shape memory alloy structure during a martensitic phase transformation to be dominated by surface roughness of the shape memory alloy structural feature.

5 . The method of claim 1 wherein the shape memory alloy structural feature has an extent that is less than about 500 microns.

6 . The method of claim 1 wherein the shape memory alloy structural feature has an extent that is less than about 250 microns.

7 . The method of claim 1 wherein the shape memory alloy structural feature has an extent that is less than about 100 microns.

8 . The method of claim 1 wherein the shape memory alloy structural feature has an extent that is greater than about 10 microns.

9 . The method of claim 1 wherein the shape memory alloy structural feature has an extent that is greater than about 100 microns.

10 . The method of claim 1 wherein the process conditions to which the shape memory alloy structural feature is exposed produces a surface roughness, R q , of the shape memory alloy structural feature that is between about 1 nm and about 100 nm.

11 . The method of claim 1 wherein the process conditions to which the shape memory alloy structural feature is exposed produces a surface roughness, R q , of the shape memory alloy structural feature that is between about 100 nm and about 150 nm.

12 . The method of claim 1 wherein the process conditions to which the shape memory alloy structural feature is exposed produces a surface roughness, R q , of the shape memory alloy structural feature that is between about 150 nm and about 200 nm.

13 . The method of claim 1 wherein the process conditions to which the shape memory alloy structural feature is exposed produces a surface roughness, R q , of the shape memory alloy structural feature that is between about 200 nm and about 300 nm.

14 . The method of claim 1 wherein the process conditions to which the shape memory alloy structural feature is exposed produces a surface roughness, R q , of the shape memory alloy structural feature that is between about 300 nm and about 400 nm.

15 . The method of claim 1 wherein the process conditions to which the shape memory alloy structural feature is exposed produces a surface roughness, R q , of the shape memory alloy structural feature that is between about 400 nm and about 500 nm.

16 . The method of claim 1 wherein the process conditions to which the shape memory alloy structural feature is exposed produces a surface roughness, R q , of the shape memory alloy structural feature that is between about 500 nm and about 1000 nm.

17 . The method of claim 1 wherein the shape memory structural feature comprises a wire and the structural feature extent comprises a diameter of the wire.

18 . The method of claim 1 wherein the process conditions to which the shape memory alloy structural feature is exposed comprise electropolishing.

19 . The method of claim 1 wherein the shape memory alloy comprises Cu—Zn—Al.

20 . The method of claim 1 wherein the shape memory alloy comprises Cu-14Al-4Ni (wt. %).

Assignees

• Massachusetts Inst Technology

Inventors

• Schuh Christopher
• Ueland Stian Melhus

Classifications

• C25F3/22

  of heavy metals · CPC title

• C22C9/04 Primary

  with zinc as the next major constituent · CPC title

• C22F1/08

  of copper or alloys based thereon · CPC title

• C22C9/01

  with aluminium as the next major constituent · CPC title