Titanium molybdenum hafnium alloy

• US 6,200,685 B1
• Filed: 02/02/1999
• Issued: 03/13/2001
• Est. Priority Date: 03/27/1997
• Status: Expired due to Term

• Current Assignee: James A. Davidson
• Original Assignee: James A. Davidson
• Inventors: Davidson, James A.
• Primary Examiner(s): Speer, Timothy M.
• Application Number:
  US09/241,812
• Time in Patent Office: 770 Days
• Field of Search: 428/472.1, 148/317, 148/421, 420/421
• US Class Current: 428/472.1
• CPC Class Codes: A61B 17/72 Intramedullary pins, nails or other devices A61B17/744 takes precedence
• CPC Class Codes: A61B 17/7275 with expanding cylindrical parts
• CPC Class Codes: A61B 17/80 Cortical plates , i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates
• CPC Class Codes: A61B 17/8635 Tips of screws
• CPC Class Codes: A61B 17/866 Material or manufacture
• CPC Class Codes: A61C 8/0012 characterised by the material or composition, e.g. ceramics, surface layer, metal alloy use of specific materials A61K6/00
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2/367 Proximal or metaphyseal parts of shafts trochanteric devices connected to said proximal parts A61F2/30739
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/3859 Femoral components
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2002/2817 Bone stimulation by chemical reactions or by osteogenic or biological products for enhancing ossification, e.g. by bone morphogenetic or morphogenic proteins [BMP] or by transforming growth factors [TGF]
• CPC Class Codes: A61F 2002/3008 radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61F 2002/30332 Conically- or frustoconically-shaped protrusion and recess
• CPC Class Codes: A61F 2002/30677 Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• CPC Class Codes: A61F 2002/30878 : with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
• CPC Class Codes: A61F 2002/30892 : parallel
• CPC Class Codes: A61F 2002/30909 : Nets
• CPC Class Codes: A61F 2002/30922 : Hardened surfaces
• CPC Class Codes: A61F 2002/3611 : Heads or epiphyseal parts of femur
• CPC Class Codes: A61F 2002/3625 : Necks
• CPC Class Codes: A61F 2002/365 : Connections of heads to necks
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2250/0098 : radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61L 27/06 : Titanium or titanium alloys
• CPC Class Codes: A61L 27/28 : Materials for coating prostheses
• CPC Class Codes: A61L 31/022 : Metals or alloys
• CPC Class Codes: A61L 31/08 : Materials for coatings
• CPC Class Codes: A61N 1/0587 : Epicardial electrode systems; Endocardial electrodes piercing the pericardium
• CPC Class Codes: A63B 2209/00 : Characteristics of used materials
• CPC Class Codes: A63B 53/04 : Heads
• CPC Class Codes: A63B 53/047 : iron-type
• CPC Class Codes: A63B 53/12 : Metallic shafts
• CPC Class Codes: A63B 60/06 : Handles
• CPC Class Codes: A63B 60/08 : characterised by the material
• CPC Class Codes: A63B 60/10 : with means for indicating correct holding positions A63B60/12 takes precedence
• CPC Class Codes: C22C 14/00 : Alloys based on titanium
• CPC Class Codes: C22F 1/183 : of titanium or alloys based thereon
• CPC Class Codes: C23C 30/00 : Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process C23C26/00, C23C28/00 take precedence
• CPC Class Codes: F16B 35/00 : Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws F16B33/008 takes precedence; joining sheets or plates using screws with two separate threads F16B5/0275; using screws with adjustment sleeves F16B5/0283; thread cutting screws F16B25/00

Abstract

This invention describes a corrosion-resistant, high-strength, low-modulus, titanium based alloy having about 5-11 weight percent Mo and about 6-15 weight percent Hf. This alloy is suitable for use in the fabrication of articles for medical and non-medical applications having low modulus, improved corrosion resistance and surface hardening. To increase strength, Cr, Si and Fe can be added in small amounts as well as increasing levels of interstitial oxygen, nitrogen or carbon. To maintain low elastic modulus, Mo can be partially substituted by Nb.

Claims

1. A titanium alloy comprising:

a) titanium;

b) between about 5 and about 11 weight percent molybdenum;

c) between about 6 and about 15 weight percent hafnium;

wherein the alloy provides for high-strength and hardness, low elastic modulus, enhanced corrosion resistance, and surface hardening.

2. The titanium alloy of claim 1, further comprising niobium partially substituting for a weight percentage of molybdenum.

3. The titanium alloy of claim 1, wherein the alloy further includes up to about 2 to about 3 weight percent of at least one element selected from the group consisting of iron, chromium and silicon.

4. The titanium alloy of claim 1, wherein the alloy includes, about 5 to 9 weight percent molybdenum, and about 6 to 9 weight percent hafnium.

5. The titanium alloy of claim 1, wherein the alloy comprises about 7 weight percent molybdenum and about 7 weight percent hafnium.

6. The titanium alloy of claim 1, wherein the alloy further includes trace levels of at least one element selected from the group consisting of oxygen, nitrogen, hydrogen and carbon.

7. An article of manufacture having at least one portion partially fabricated from a metal alloy comprising:

a) titanium;

b) between about 5 and about 11 weight percent molybdenum;

c) between about 6 and about 15 weight percent hafnium;

wherein the alloy provides for high-strength and hardness, low elastic modulus, enhanced corrosion resistance, and surface hardening of said portion of said article.

8. The article of claim 7, wherein the alloy further includes up to about 2 to 3 weight percent of at least one element selected from the group consisting of iron, chromium and silicon.

9. The article of claim 7, wherein additional interstitial strengthening of the alloy is achieved by increased levels of an element selected from the group consisting of oxygen, nitrogen, hydrogen and carbon.

10. The article of claim 7, wherein the alloy composition is titanium, about 5 to 9 weight percent molybdenum, and about 6 to about 9 weight percent hafnium.

11. The article of claim 7, wherein the alloy composition is titanium, about 7 weight percent molybdenum and about 7 weight percent hafnium.

12. The article of claim 7, wherein said portion of said article is surface hardened by a process selected from the group consisting of oxidation and nitriding to form a hard, diffusion bonded, conversion surface oxide or nitride.

13. The article of claim 12, wherein said portion of said article is coated with a low friction coating.

14. The article of claim 7, wherein the alloy is mechanically hot-worked to optimize the grain size, strength, modulus, and toughness of the alloy.

15. The article of claim 7, wherein the alloy is cold worked to optimize the grain size, strength, modulus, and toughness of the alloy.

16. The article of claim 15, wherein the alloy is an alloy that is at least partially heat treated after being cold-worked.

17. The article of claim 15, wherein the alloy is an alloy that is at least partially heat treated by an aging treatment after being cold-worked.

18. The article of claim 15, wherein the alloy is an alloy that is heat treated above about 900°

C. and then air cooled.

19. The article of claim 7, wherein the alloy is a near beta titanium alloy that is quenched to form a martensitic microstructure and then aged to increase strength and bulk hardness.

20. The article of claim 7, wherein the alloy is a near beta titanium alloy that is quenched to form a martensitic microstructure and then cold-worked to increase alloy strength and reduce alloy elastic modulus.

21. A titanium alloy suitable for use in the fabrication of a variety of articles, said alloy comprising:

(a) titanium;

(b) between about 5 to about 11 weight percent molybdenum;

(c) between about 6 to about 15 weight percent hafnium;

(d) up to about 2 to about 3 weight percent of at least one element selected from the group consisting of iron, chromium and silicon;

(e) trace levels of an element selected from the group consisting of oxygen, nitrogen, hydrogen, and carbon; and

wherein the alloy provides for high-strength and hardness, low elastic modulus, enhanced corrosion resistance, and surface hardening.

22. The titanium alloy of claim 21, further comprising between about 5 to about 10 weight percent niobium.

23. The titanium alloy of claim 21, further comprising niobium partially substituting for a weight percentage of molybdenum.