HYPERELASTIC SHAPE SETTING DEVICES AND FABRICATION METHODS

• US 20090139613A1
• Filed: 12/03/2007
• Published: 06/04/2009
• Est. Priority Date: 12/03/2007
• Status: Active Grant

• Current Assignee: Ormco Corporation (Envista Holdings Corporation)
• Original Assignee: TiNi Alloy Company
• Inventors: Johnson, Alfred David, Martynov, Valery, Gray, George R., Bokaie, Michael D.
• Granted Patent: US 7,842,143 B2
• Time in Patent Office: Days
• US Class Current: 148/562
• CPC Class Codes: C21D 2201/01 Shape memory effect
• CPC Class Codes: C21D 2201/04 Single or very large crystals
• CPC Class Codes: C22F 1/006 Resulting in heat recoverable alloys with a memory effect
• CPC Class Codes: C30B 1/04 Isothermal recrystallisation
• CPC Class Codes: C30B 29/52 Alloys

Abstract

Shape-setting methods for fabricating devices made of single crystal shape memory alloys. The method include drawing a single crystal of a shape memory alloy from a melt of the alloy. This is followed by heating and quenching the crystal sufficiently rapid to limit the formation of alloy precipitates to an amount which retains hyperelastic composition and properties of the crystal.

Claims

1. A method of shape-setting a device that is comprised of a single crystal shape memory alloy, the method comprising the steps of heating the device to a first temperature sufficient for annealing the alloy, forming the device into a shape, constraining the device while in the shape, heating the device to a second temperature and within a first time period with the second temperature and first time period being sufficient to cause the alloy to lose its strength, and cooling the device to a third temperature and within a second time period with the third temperature and second time period being sufficient to cause the alloy to form a single crystal.

2. A method as in claim 1 in which the forming step is carried out by forming the shape of device into a wire shape, providing a tube which generally conforms to the shape of the wire, and inserting the wire into the tube.

3. A method as in claim 2 in which the step of providing a tube comprises providing a tube of stainless steel.

4. A hyperelastic device made by the method steps of claim 1.

6. A device made by the method steps of claim 2 in which the forming step comprises providing a wire with a given diameter, and bending the wire to a shape having a bending radius less than 5 times the given diameter.

5. A hyperelastic device made by the steps of providing a single crystal of a shape memory alloy that is drawn from a melt of the alloy, heating and then cooling the crystal in a time period which is sufficient to limit the formation of alloy precipitates to an amount which retains hyperelastic composition and properties of the crystal.