WO2015183990A2 - Titanium-based alloys and articles formed from such alloys - Google Patents

Abstract

Article(s) are disclosed that are formed, at least in part, by a titanium-based alloy having about 35 to about 55 wt. % or greater titanium, the article(s) have a hardness of about 1350 HV or greater, and a coloration characterized by an L value of about 56.00 to about 60.00, an a value of about 1.0 to about 1.5, and a b value of about 3.65 to about 3.75, wherein the L, a, and b values are color values according to the CIE L*a*b* color scale.

Description

TITLE OF INVENTION

TITANIUM-BASED ALLOYS AND ARTICLES FORMED FROM SUCH ALLOYS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. Provisional Application Serial No. 62/003,514 filed 27 May 2014, which is incorporated herein by reference in its entirety

BACKGROUND

[0002] The present application generally relates to compositions of matter and articles of manufacture, such as jewelry items.

[0003] In this specification where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.

[0004] Jewelry such as finger rings, pendants, bracelets, and necklaces have traditionally been made of soft metals such as gold, silver and platinum because those metals are malleable, and easily formed by casting, forging and molding. Recently, jewelry items have been formed from harder materials such as alloys or composites such as "cermets." An alloy is a mixture or metallic solid solution composed of two or more elements. A cermet is a composite material composed of a ceramic and metallic material. Typically, a metal is used as a binder for an oxide, boride, nitride, or carbide.

[0005] Some specific attempts to form jewelry from these types of materials include alloys or composites having titanium, zirconium (U.S. Patent 3,669,695), titanium-niobium-zirconium (U.S. Patent 6,759,134) and tungsten carbide (U.S. Patents 6,553,667; 6,990,736; 6,993,842; 7,032,314; 7,076,972). Such jewelry is much more resistant to scratching and other damage than traditional jewelry made of softer metals. Additionally, certain alloys containing these metals, prepared under certain conditions, have an attractive dark grey or black color. See, e.g., U.S. Patent 6,759,134, describing articles made from an alloy of 51 -70 weight-percent (wt%) titanium, 3-17% niobium, and the balance zirconium, tantalum, molybdenum, hafnium zirconium, chromium, or mixtures thereof, having a black surface layer of a niobium oxide.

[0006] Additional alloy and composite formulations providing desirable jewelry characteristics would be advantageous. The articles provided herewith address that need. In particular, conventional jewelry materials can possess one or more of the following deficiencies and/or disadvantages:

^* traditional formulations can be too heavy;

^* traditional formulations may not possess an optimal aesthetic coloration and/or shine or luster; and

^* traditional formulations may lack sufficient hardness.

[0007] While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass or include one or more of the conventional technical aspects discussed herein.

SUMMARY

[0008] It has been discovered that articles made from certain titanium-based alloys, such as, for example, alloys having about 35 % to about 55 % Ti, among other constituents, which will be described in further detail herein, advantageously, according to certain embodiments, possess a unique combination of desirable features. For example, alloys formed according to the principles of the present invention possess desirable coloration, hardness and density properties which makes them particularly attractive for use in forming certain articles, such as articles of jewelry.

[0009] Thus, according to one aspect of the present invention, there is provided an article comprising a titanium-based alloy having about 35 wt.% to about 55 wt.% titanium, the article having a hardness of about 1300 HV or greater, and a coloration characterized by an "L" value of about 56 to about 60, an "a" value of about 1 .0 to about 1 .5, and a "b" value of about 3.7 to about 3.8, wherein the L, a, and b values are color values according to the CIE L^*a^*b^* color scale.

[0010] An article formed according to the principles of the present invention may further possess a density of about 6.0 to about 6.35 g/cm3.

[0011] The remainder of the alloy composition may have one or more of: Si, Ta, Al, Mn, Nb, Zr and O.

[0012] The article of can be in the form of an item of jewelry.

[0013] The article may be in the form of a ring, a pendant, a dog tag, a hairclip, a chain, a watchcase, a pin, a bracelet, a necklace, an earring or a charm.

[0014] The article may be in the form of a finger ring.

[0015] The article may include at least one of a precious metal, a stone, a gemstone, a crystal, or another material suitable for use in jewelry affixed to the article.

[0016] The article may be in the form of a finger ring, and my have at least one depression that extends into, and at least substantially around the circumference of, an outer surface of the finger ring, wherein the depression is substantially filled with a material, such as metal, or a precious metal.

[0017] The present invention may address one or more of the problems and deficiencies of the prior art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies, or provide benefits and advantages, in a number of technical areas. Therefore the claimed invention should not necessarily be construed as being limited to addressing any of the particular problems or deficiencies discussed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a perspective view of a plain band-like finger ring in accordance with an illustrative embodiment.

[0019] FIGS. 2A-2B are perspective views of finger rings that were machined in accordance with an alternate illustrative embodiments.

[0020] FIG. 3 is a view of a finger ring that has been decoratively machined in accordance with another alternate illustrative embodiment. [0021] FIG. 4 is a view of a finger ring with a diamond inset. DETAILED DESCRIPTION

[0022] As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Additionally, the use of "or" is intended to include "and/or", unless the context clearly indicates otherwise.

[0023] As used herein, "about" is a term of approximation and is intended to include minor variations in the literally stated amounts, as would be understood by those skilled in the art. Such variations include, for example, standard deviations associated with techniques commonly used to measure the amounts of the constituent elements or components of an alloy or composite material.

[0024] All of the numerical values contained in this disclosure are to be construed as being characterized by the above-described modifier "about," are also intended to include the exact numerical values disclosed herein. Moreover, all ranges include the upper and lower limits.

[0025] All percentages disclosed herein refer to percent by weight, relative to the overall weight of the composition, unless otherwise described herein. The weight percentages disclosed herein were measured by an Inductively Coupled Mass

Spectrometry ("ICP-MS"). ICP-MS is a type of mass spectrometry capable of accurately measuring metals and non-metals at very low concentrations. The sample is ionized by inductively coupled plasma and then the ions are separated and quantified by a mass spectrometer. This technique is familiar to those skilled in the art.

[0026] The "HV" hardness number values described herein refer to the hardness value measured according to the Vickers hardness test, performed according to the ASTM:E384-1 1⁸¹ standard (last revised March 2012).

[0027] As used herein, "L," "a," and "b," refer to the color values measured according to the CIE 1976 (L^*, a^*, b^*) color space (or CIELAB) scale. These values disclosed herein were measured by a Konica Minolta Spectrophotometer model CM- 600. [0028] All of the stated compositions and methods disclosed herein are to be construed as "comprising," "consisting essentially of," and "consisting of" the stated constituents and method steps.

[0029] Articles formed according to the principles of the present invention are formed, at least in part, from a particular alloy composition. According to certain embodiments, the alloy composition is titanium-based. According to further

embodiments, the alloy composition further includes, in addition to titanium, one or more of tungsten, nickel, chromium, carbon, molybdenum and/or copper.

[0030] According to further alternative embodiments, the alloy composition is selected from a combination of one or more, or all, elements listed in the table below, in any of the amounts described in the Table.

[0031] TABLE 1

[0032] With respect to Ti, the alloy composition may include about 35 - 55 wt.% of Ti. Amounts of Ti below this threshold are not preferred because depending on which materials are used to replace Ti, the weight of the composition could increase, the hardness of the composition could decrease, the coloration may be modified in an unfavorable manner, and less than optimal or unfavored optical properties such as reflectivity, and other undesired changes to the composition may result. Compositions that include Ti in amounts beyond the upper limit of this range are not preferred because , depending on which materials replace Ti in the composition, the alloy could exhibit increased brittleness, undesirable modification coloration, reduced machine ability, and unfavorable changes in optical properties such as reflectivity, and/or other undesired changes to the properties of composition. [0033] With respect to W, the alloy composition may include no more than about 60 wt. % W. According to further embodiments, the alloy contains no more than about 20% wt.% W. According to further optional embodiments, the alloy composition includes at least about 10 wt. % W.

[0034] With respect to Ni, the alloy composition may include about 5 to about 20 wt.% Ni. Compositions that include Ni in amounts below the minimum value of this range are not preferred because such compositions tend to exhibit increased hardness of the solid solution elements, and resulting increases in brittleness. Compositions that include Ni in amounts above the maximum value of this range are not preferred because such compositions exhibit a decrease in hardness of the alloy which in turn will decrease the hardness, where resistance, corrosion resistance, as well as increase the risk of allergic reaction based on the EN181 1/201 1 standard.

[0035] With respect to Cr, the alloy composition may include no more than about 2 wt.% Cr. Amounts of Cr above this level are not preferred because such

compositions exhibit undesired changes in coloration, optical properties such as reflectivity, hardness, and ductility. According to further optional embodiments, the alloy composition includes about 0 to about 5 wt.% Cr. Compositions that include Cr in amounts below the lower limit of this range are not preferred because such

compositions exhibit undesirable changes in coloration, optical properties such as reflectivity, hardness, and ductility.

[0036] Carbon exists in the composition in the form of a carbide with W and Ti in solid solution. With respect to C, the alloy composition may include about 10 wt.% or greater C. Amounts of C below this threshold are not preferred because enough carbon should be present such that it can form carbides with W and Ti in solid solution.

According to further optional embodiments, the alloy composition includes about 8 to about 20 wt.% C. Compositions that include C in amounts beyond the upper limit of this range are not preferred because compositions having carbon in such amounts form excess carbides which in turn result in increased brittleness of sintered parts and cause unwanted binding or carbonization with other free elements. [0037] With respect to Mo, the alloy composition may include about 6.5 wt.% or greater Mo. Amounts of Mo below this threshold are not preferred because unfavorable changes in ductility, coloration and reflectivity of the composition may result. According to further optional embodiments, the alloy composition includes about 3 to about 10 wt.% Mo. Compositions that include Mo in amounts beyond the upper limit of this range are not preferred because substantial changes in ductility, coloration, composition and reflectivity may occur. As an example, a substantial increase in ductility will make the finished parts, such as parts in the form of a finger ring, difficult to remove by breaking in a vice in the event of an emergency, thus necessitating the use of more dangerous and less favorable means (e.g., wet cutting using a circular diamond grinding wheel) in order to break the ring and remove it from the finger if necessary.

[0038] With respect to Cu, the alloy composition may include about 0.5 to about 2.0 wt.% Cu. Compositions that include Cu in amounts below the minimum value of this range are not preferred because property such as ductility, fusion temperature and coloration may be impacted in an adverse manner. Compositions that include Cu in amounts above the maximum value of this range are not preferred because such compositions increase the potential peroxidation breakdown of the metal matrix, thereby decreasing the where resistance and lifespan of finished articles such as jewelry pieces.

[0039] Alloy compositions formed according to the principles of the present invention may include, in addition to the above-described elements, one or more of the following constituent elements, in relatively minor amounts: Si, Ta, Al, Mn, Nb, Zr, and/or O.

[0040] Alloy compositions formed according to further embodiments of the present invention preferably do not include cobalt (Co) or iron (Fe). More specifically, neither Co nor Fe are intentionally added as constituent components of the alloy composition. However, trace amounts of these elements may be found in compositions formed according to the present invention. For example, modern steelmaking

techniques utilizing commercially available starting materials may introduce trace amounts of these elements into the composition unintentionally. [0041] According to one specific exemplary, and non-limiting embodiment, article formed from an alloy according to the principles of the present invention possesses the following:

[0042] TABLE 2

[0043] In some embodiments, the entire article is made from the alloy. In other embodiments, only a portion of the article is made from the alloy. For example, the decorative portion of a pin can be made from the alloy and the rest of the pin can be made from standard materials. Where the article is a finger ring, the alloy can comprise the majority of the ring, except for an inlaid gemstone, or an inlay in an annular groove formed in the alloy, e.g., as illustrated in relation to rings made from tungsten carbide in U.S. Patent 7,076,972. Those rings have at least one depression that extends into, and at least substantially around the circumference of, an outer surface of the finger ring. In some embodiments, the depression in those rings is substantially filled with a precious metal.

[0044] In additional embodiments, the alloy can comprise a minority of the article, for example as a portion of a sculpture primarily made of other materials, or as a contrasting band in a ring made primarily from another metal such as gold or silver.

[0045] In some embodiments, the article is a decorative or artistic item, for example, a sculpture, a portion of a picture frame, a paperweight, a portion of a piece of furniture {e.g., an inlay), or jewelry. Nonlimiting examples of jewelry that can be made from the Ti-based alloy are rings {e.g., finger rings, toe rings, nose rings), pendants, tags, dog tags, hairclips, chains, watchcases, pins, bracelets, anklets, necklaces, earrings and charms.

[0046] The item of jewelry comprising the alloy can further comprise any other material used in jewelry affixed or integrated into the item. Examples include a precious metal {e.g., gold, silver, platinum) either as part of the alloy or affixed to the item, a stone, a gemstone, a crystal, or any other material suitable for use in jewelry affixed to the item.

[0047] In particular embodiments, the item of jewelry is a finger ring. The ring can be made entirely of the alloy, or the ring can further comprise other materials, for example an inlaid gemstone, or an inlay in an annular groove formed in the alloy.

Illustrative examples of finger rings are provided in FIGS. 1 -4. FIG. 1 shows a plain band-like ring made from the Ti-based alloy described herein. FIGS. 2A-2B show other examples of finger rings made from the Ti-based alloy. These rings were machined after preparation. FIG. 3 shows an additional example of a finger ring made from the Ti- based alloy that has a decorative pattern machined therein. FIG. 4 illustrates a ring having a diamond set therein as a further example of a finger ring made from the Ti- based alloy. [0048] The articles provided here can be made by any method known. In some embodiments, an ingot, bar, sheet or other form of the alloy is provided, followed by cutting, shaping and polishing the ingot or bar to form a piece having a desired shape, then optionally polishing the piece with a finish polish.

[0049] A "blank" of the article can then be cut from the bar or sheet, for example using wire electric discharge machining (EDM). Any internal areas that need to be hollowed out of the blank {e.g., the center portion of a ring) can be removed, e.g., using a sink EDM. A CNC lathe can then be used to prepare the outer shape of the article, followed by polishing. At this point, any inlays, setting or engraving can be performed. Where the article is a ring or similar article that requires internal sizing, a CNC lathe, followed by an inner polish can be used at this point.

[0050] After the above shaping of the article, the article can be subjected to one or more heat treatment(s), followed by final polishing followed and any additional engraving desired, for example using a CNC lathe or CNC engraving.

[0051] Alternatively, articles having any of the compositions described herein can be formed by a powder metallurgy process, wherein the above-described constituent components are blended in powder form, then pressed or injected to form a blank. The constituents described herein may be provided in their elemental powdered form.

Alternatively, the powders may themselves be combinations of different metals or constituent components. The blank may approximate the final shape or form of the article. This is often referred to as "near-net-shape." The blank can them be

consolidated by sintering. The result of the sintering is a dense object possessing the desired coloration, etc. One non-limiting example of a possible powder metallurgy based formation technique is Hot Isostatic Pressing (HIP).

[0052] An article, such as any of the articles of jewelry described herein, formed at least in part from cermet can be produced by any suitable technique that results in a dense object having the desired physical properties as well as the desired coloration. For example, suitable methods may comprise combining the constituent elements in powder form, pressing or injecting the powders to form a blank or near net-shape object, and sintering to consolidate the blank or object and provide a grey/dark grey/black appearance. Examples of specific techniques for pressing, injecting, molding and sintering to form a final article, such as an article of jewelry, have been previously described above in connection with powder metallurgical techniques. These techniques can also be used to form articles, such as articles of jewelry, and are incorporated herein by reference. For example, the methods or techniques described in the United States Patent Application Publication No. US 2012-0304694 may be used, the content of which is incorporated herein by reference in its entirety.

[0053] Articles formed according to the principles of the present invention, including the articles of jewelry described herein, may have one or more advantageous properties and/or characteristics.

[0054] According to certain embodiments, articles formed according to the principles of the present invention possess a Vickers hardness number (HV) of about 900HV, 1200HV, 1300HV or greater, according to one specific, illustrative, and non- limiting example, an article formed according to the principles of the present invention possesses an HV value of about 1350HV, or greater than 1350HV.

[0055] According to additional embodiments of the present invention, an article formed according to the principles of the present invention possesses a coloration characterized by a range of L, a, and b values. More specifically, articles formed according to the principles of the present invention possess a "L" value of about 57 to about 59. According to further embodiments, the articles further possess an "a" value of about 1 .0 to about 1 .5. According to additional embodiments, the articles further possess a "b" value of about 3.7 to about 3.8. According to one illustrative, non-limiting example, an article formed according to the principles of the present invention

possesses a coloration characterized as: L= about 58.01 , a = about 1 .08, and b = about 3.74.

[0056] According to still other embodiments of the present invention, articles can be formed which possess a favorable density property. More specifically, articles formed according to the principles of the present invention may possess density values of about 6.0 to about 6.35 g/cm³. According to one specific, illustrative, and non-limiting example, an article formed according to the principle the present invention possesses a density value of about 6.2 g/cm³.

[0057] When compositions formed according to the principles of the present invention are utilized to produce articles of jewelry to be worn on the body, another important property is the ability of such articles formed thereby to be removed from the body in the event of an emergency. Thus, the compositions formulated according to the principles of the present invention have been designed to serve the need of a lightweight scratch resistant product, yet still have the ability to be removed by conventional techniques involving applying pressure to the article jewelry in a vice-like handheld or stationary tool. Alternatively, a welding laser can be used to weaken the structure of the article jewelry. When such a welding laser is used, cool and should be used in conjunction with a moderately applied laser contact. Once the surface of the ring has been compromised, it can be more easily fractured and removed. Appropriate settings for such an industrial welding laser may include: voltage (220 V-240 V), cycle (5-5.5 Hz), and application time (3.25-3.5 milliseconds).

[0058] A similar consideration of the composition when utilized to produce finished articles in the form of jewelry is the ease in which the material can be engraved or removed for decorative purposes. Accordingly, the compositions formulated according to the principles of the present invention have been designed so as to facilitate laser engraving of decorative patterns thereon, and the like. Appropriate laser settings can be determined by those skilled in the art. According to certain illustrative and nonlimiting examples, appropriate laser settings may include: power (19.8 W), cycle speed (7000 Hz), rotation speed (100 mm/s). A desirable depth of cut can be achieved to render an aesthetically pleasing design.

[0059] Other embodiments within the scope of the claims herein will be apparent to one skilled in the art from consideration of the specification or practice of the invention as disclosed herein. It is intended that the specification be considered exemplary only, with the scope and spirit of the invention being indicated by the claims.

[0060] In view of the above, it will be seen that the several advantages of the invention are achieved and other advantages attained. [0061] As various changes could be made in the above methods and compositions without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

[0062] All references cited in this specification are hereby incorporated by reference. The discussion of the references herein is intended merely to summarize the assertions made by the authors and no admission is made that any reference

constitutes prior art. Applicants reserve the right to challenge the accuracy and pertinence of the cited references.

[0063] Any numbers expressing quantities of ingredients, constituents, reaction conditions, and so forth used in the specification are to be understood as being modified in all instances by the term "about." Notwithstanding that the numerical ranges and parameters setting forth, the broad scope of the subject matter presented herein are approximations, the numerical values set forth are indicated as precisely as possible. Any numerical value, however, may inherently contain certain errors or inaccuracies as evident from the standard deviation found in their respective measurement techniques. None of the features recited herein should be interpreted as invoking 35 U.S.C. §1 12, 6, unless the term "means" is explicitly used.

Claims

CLAIMS:

Claim 1 . An article comprising a titanium-based alloy having about 35 to about 55 wt. % titanium, the article having a hardness of about 1350HV or greater, and a coloration characterized by an L value of about 56.00 to about 60.00, an a value of about 1 .0 to about 1 .5, and a b value of about 3.65 to about 3.75, wherein the L, a, and b values are color values according to the CIE L^*a^*b^* color scale.

Claim 2. The article of claim 1 , wherein the article has a density of about 6.0 to about 6.35 g/cm³.

Claim 3. The article of any one of claims 1 -2, wherein the alloy has about 45 wt.

% Ti.

Claim 4. The article of any one of claims 1 -3, wherein the alloy has no more than about 60 wt. % W.

Claim 5. The article of any one of claims 1 -4, wherein the alloy has about 10 to about 60 wt. % W.

Claim 6. The article of any one of claims 1 -5, wherein the alloy has about 5 to about 15 wt. % C.

Claim 7. The article of any one of claims 1 -6, wherein the alloy has about 12.7 wt. % C.

Claim 8. The article of any one of claims 1 -7, wherein the alloy comprises no more than about 10 wt. % Cr.

Clainn 9. The article of any one of claims 1 -8, wherein the alloy comprises about .001 to about 10 wt. % Cr.

Claim 10. The article of any one of claims 1 -9, wherein the alloy comprises about .001 to about 10 wt. % Mo.

Claim 1 1 . The article of any one of claims 1 -10, wherein the alloy comprises about 6.5 wt. % or greater Mo.

Claim 12. The article of any one of claims 1 -1 1 , wherein the alloy comprises about 0.5 to about 1 .75 wt. % Cu.

Claim 13. The article of any one of claims 1 -12, wherein the alloy comprises no more than trace amounts of Co and Fe.

Claim 14. The article of any one of claims 1 -13, wherein the alloy comprises:

Ti: about 35 to about 55 wt. %;

W: about 10 to about 60 wt. %;

Ni: about 5 to about 20 wt. %;

Cr: about .001 to about 10 wt. %;

C: about 5 to about 15 wt. %;

Mo: about .001 to about 10 wt. %; and

Cu: about 0.5 to about 1 .75 wt. %.

Claim 15. The article of any one of claims 1 -14, wherein the remainder of the alloy composition comprises one or more of: Si, Ta, Al, Mn, Nb, Zr and O.

Claim 16. The article of any one of claims 1 -15, wherein the article is an item of jewelry.

Claim 17. The article of claim 16, wherein the item of jewelry is a ring, a pendant, a dog tag, a hairclip, a chain, a watchcase, a pin, a bracelet, a necklace, an earring or a charm.

Claim 18. The article of any one of claims 16-17, wherein the item of jewelry is a finger ring.

Claim 19. The article of any one of claims 16-18, further comprising at least one of a precious metal, a stone, a gemstone, a crystal, or another material suitable for use in jewelry affixed to the article.

Claim 20. The article of claim 18, wherein the finger ring has at least one depression that extends into, and at least substantially around the circumference of, an outer surface of the finger ring, wherein the depression is substantially filled with a material.

Claim 21 . The article of claim 20, wherein the material is a metal.

Claim 22. The article of claim 21 , wherein the metal is a precious metal.