# US 11,111,571 B2 · Ni-free beta Ti alloys with shape memory and super-elastic properties

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- Number: US 11,111,571 B2
- Document ID: US11111571B2
- Status: Granted
- Kind: B2
- Application number: 16/349,498
- Filed: 2016-11-14
- Published: 2019-09-26
- Granted: 2021-09-07
- Earliest claimed: 2016-11-14
- Assignees: Fort Wayne Metals Research Products Corporation
- Applicants: Fort Wayne Metals Research Products Corp
- Inventors: Song Cai; Jeremy E. Schaffer; Adam J. Griebel
- Web page: https://patentgrep.com/patent/US11111571B2

## CPC

- C22F 1/006: {Resulting in heat recoverable alloys with a memory effect}
- A61L 31/022: {Metals or alloys}
- A61L 31/14: Materials characterised by their function or physical properties {, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials}
- C22C 14/00: Alloys based on titanium
- C22C 27/00: Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
- C22C 30/00: Alloys containing less than 50% by weight of each constituent
- C22C 30/04: containing tin or lead
- C22F 1/18: High-melting or refractory metals or alloys based thereon
- C22F 1/183: {of titanium or alloys based thereon}
- A61L 2400/16: Materials with shape-memory or superelastic properties
- C22F: CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass, C23F17/00)
- A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K)
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

A group of substantially nickel-free beta-titanium alloys have shape memory and super-elastic properties suitable for, e.g., medical device applications. In particular, the present disclosure provides a titanium-based group of alloys including 16-20 at. % of hafnium, zirconium or a mixture thereof, 8-17 at. % niobium, and 0.25-6 at. % tin. This alloy group exhibits recoverable strains of at least 3.5% after axial, bending or torsional deformation. In some instances, the alloys have a capability to recover of more than 5% deformation strain. Niobium and tin are provided in the alloy to control beta phase stability, which enhances the ability of the materials to exhibit shape memory or super-elastic properties at a desired application temperature (e.g., body temperature). Hafnium and/or zirconium may be interchangeably added to increase the radiopacity of the material, and also contribute to the superelasticity of the material.

## Claims

### Claim 1

A substantially nickel-free beta-titanium alloy, comprising:
between 16 at. % and 20 at. % hafnium, zirconium, or a combination thereof, wherein the alloy includes a minimum of 1 at. % hafnium;
between 8 at. % and 17 at. % niobium;
between 0.25 at. % and 6 at. % tin; and
balance titanium and impurities,
wherein the alloy exhibits superelastic behavior with an isothermally recoverable strain of at least 3.5%, and
wherein the alloy is formed into a shape set component.

### Claim 2 (depends on 1)

The alloy of claim 1, wherein the alloy exhibits superelastic behavior with an isothermally recoverable strain of at least 5%.

### Claim 3 (depends on 1)

The alloy of claim 1, wherein the alloy includes zirconium, with a ratio of hafnium to zirconium between 3:1 and 1:17.

### Claim 4 (depends on 1)

The alloy of claim 1, wherein the alloy includes between 16 at. % and 20 at. % hafnium and substantially no zirconium.

### Claim 5 (depends on 1)

The alloy of claim 1, wherein the alloy exhibits the superelastic behavior at body temperature.

### Claim 6 (depends on 1)

The alloy of claim 1, wherein the alloy is biocompatible.

### Claim 7 (depends on 1)

The alloy of claim 1, wherein the shape set component is a drawn component.

### Claim 8 (depends on 7)

The alloy of claim 7, wherein the drawn component is one of a wire, a tube and a rod.

### Claim 9 (depends on 7)

The alloy of claim 7, wherein the drawn component is a wire having a cross-sectional area between 0.13×10−6 and 63.6×10−6 square inches and a ratio of hafnium to zirconium between 3:1 and 10:1.

### Claim 10 (depends on 7)

The alloy of claim 7, wherein the drawn component is a wire having a cross-sectional area between 63.6×10−6 and 176.7×10−6 square inches and a ratio of hafnium to zirconium between 3:1 and 1:5.

### Claim 11 (depends on 7)

The alloy of claim 7, wherein the drawn component is a wire having a cross-sectional area between 176.7×10−6 and 706.9×10−6 square inches and a ratio of hafnium to zirconium between 1:5 and 1:8.

### Claim 12 (depends on 7)

The alloy of claim 7, wherein the drawn component is a rod having a cross-sectional area between 5.0×10−3 and 31.4×10−3 square inches and a ratio of hafnium to zirconium between 1:8 and 1:17.

### Claim 13 (depends on 7)

The alloy of claim 7, wherein the drawn component is a composite wire comprising a shell having a central cavity and a core received within the shell.

### Claim 14 (depends on 1)

The alloy of claim 1, wherein the alloy has retained cold work between 75% and 99%.

### Claim 15 (depends on 1)

The alloy of claim 1, wherein the alloy comprises between 2.0 and 5.0 at. % tin.

### Claim 16 (depends on 1)

The alloy of claim 1, wherein the alloy comprises less than 500 parts per million of nickel.

### Claim 17 (depends on 1)

The alloy of claim 1, wherein the alloy comprises less than 0.01 wt. % nickel.

### Claim 18 (depends on 1)

The alloy of claim 1, wherein the alloy exhibits fatigue strength such that the alloy survives 0.5% alternating strain for 106 cycles.

### Claim 19 (depends on 1)

The alloy of claim 1, wherein the alloy exhibits an ultimate tensile strength which reaches 120 ksi.

### Claim 20

A substantially nickel-free beta-titanium material, comprising:
between 16 at. % and 20 at. % hafnium, zirconium, or a combination thereof, wherein the alloy includes a minimum of 1% hafnium;
between 8 at. % and 17 at. % niobium;
between 0.25 at. % and 6 at. % tin; and
balance titanium and impurities,
wherein the material exhibits superelastic behavior with a isothermally recoverable strain of at least 3.5%, and
wherein the material is a drawn construct.

### Claim 21 (depends on 20)

The material of claim 20, wherein the material exhibits superelastic behavior with an isothermally recoverable strain of at least 5%.

### Claim 22 (depends on 20)

The material of claim 20, wherein the material includes zirconium, with a ratio of hafnium to zirconium between 3:1 and 1:17.

### Claim 23 (depends on 20)

The material of claim 20, wherein the material includes between 16 at. % and 20 at. % hafnium and substantially no zirconium.

### Claim 24 (depends on 20)

The material of claim 20, wherein the drawn construct is one of a wire, a tube and a rod.

### Claim 25 (depends on 20)

The material of claim 20, wherein the drawn construct has retained cold work between 75% and 99%.

### Claim 26 (depends on 20)

The material of claim 20, wherein the material comprises between 2.0 and 5.0 at. % tin.

### Claim 27 (depends on 20)

The material of claim 20, wherein the material comprises less than 500 parts per million of nickel.

### Claim 28 (depends on 20)

The material of claim 20, wherein the drawn construct comprises less than 0.01 wt. % nickel.

### Claim 29 (depends on 20)

The material of claim 20, wherein the drawn construct exhibits fatigue strength such that the material survives 0.5% alternating strain for 106 cycles.

### Claim 30 (depends on 20)

The material of claim 20, wherein the drawn construct exhibits an ultimate tensile strength which reaches 120 ksi.

### Claim 31 (depends on 20)

The material of claim 20, wherein the alloy exhibits the superelastic behavior at body temperature.

### Claim 32 (depends on 20)

The material of claim 20, wherein the alloy is biocompatible.