WO2012053911A2

WO2012053911A2 - Metal alloy

Info

Publication number: WO2012053911A2
Application number: PCT/NZ2011/000219
Authority: WO
Inventors: Hugh Joseph Gillbanks; Kotin Hau Chuen Ma
Original assignee: Hugh Joseph Gillbanks; Kotin Hau Chuen Ma
Priority date: 2010-10-19
Filing date: 2011-10-19
Publication date: 2012-04-26
Also published as: AU2011318682A1; WO2012053911A3; AU2011318682B2

Abstract

The present invention relates to a metal alloy with by weight from about 95% to about 99% platinum metal, about 1.5% to about 4% of a group IB metal, and about 0.001% to about 5% of an additional alloying element selected from the group consisting of: iron, nickel, and a combination of iron and nickel. Preferably, the metal alloy consists of about 95% to about 99% platinum, about 1.5% to about 4% of silver, and about 0.001% to about 5% iron meteorite. The metal alloy has improved castability, resistance to porosity, resistance to shrinkage, pitting and cracking when worked, ductility, soldering properties (thermal conductivity and heat capacity), remelting, electrical conductivity.

Description

METAL ALLOY

STATEMENT OF CORRESPONDING APPLICATIONS

The present invention is based on the provisional specifications filed in relation to New Zealand Patent Application No. 588666, the entire contents of which are incorporated herein.

TECHNICAL FIELD

The present invention relates to a metal alloy composition comprising a platinum metal, a group IB metal and at least one additional alloying element that includes iron, nickel or iron and nickel. BACKGROUND ART

The attractiveness of palladium as a precious metal in terms of its price and density is evident when compared to other precious metals. Palladium is approximately 3.9 times less expensive than gold and approximately 5.3 times less expensive than platinum per unit volume. However, pure palladium is disadvantageous for most practical uses due to mechanical factors such as low tensile strength and hardness. Attempts to improve the mechanical properties of pure palladium have resulted in only a limited number of metal alloys with limited success.

There is a desire to create a metal alloy made substantially of palladium that does not incur the mechanical disadvantages of pure palladium. It is an object of the present invention to provide a metal alloy which overcomes or at least ameliorates some of the abovementioned disadvantages or which at least provides the public with a useful choice.

Other objects of the invention may become apparent from the following description which is given by way of example only.

All references, including any patents or patent applications cited in this

specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinence of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein; this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in Australia or in any other country. It is acknowledged that the term 'comprising' may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term 'comprising' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised' or 'comprising' is used in relation to one or more steps in a method or process.

DISCLOSURE OF INVENTION

In one aspect the invention relates to a metal alloy comprising from about 95 to about 99% platinum metal, about 1.5 to about 4% of a group IB metal, and about 0.001 to about 5% of an additional alloying element selected from the group consisting of: iron, nickel, and a combination of iron and nickel.

As used herein the term "group IB metal" or its grammatical equivalents and derivatives means a metal in the Periodic Table Group 1 1 consisting of gold, silver, copper and roentgenium. In a further aspect the invention relates to a metal alloy having a composition consisting essentially of a platinum metal, a group IB metal and an additional alloying element selected from iron, nickel, or a combination of iron and nickel.

In a further aspect the invention relates to a metal alloy comprising from about 95 to about 99% platinum metal, about 1.5% to about 4% of a group IB metal and about 0.001 % to about 5% iron meteorite.

In a further aspect the invention relates to a metal alloy having a composition consisting essentially of a platinum metal, a group IB metal, and iron meteorite.

In a further aspect the invention relates to a metal alloy consisting essentially of about 95% to about 99% palladium metal, about 1.5% to about 4% of a group IB metal and about 0.001 % to about 5% of an additional alloying element selected from iron, nickel, and a combination of iron and nickel.

The following embodiments may relate to any of the above aspects.

In some embodiments the metal alloy comprises at least about 95%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99% or 99.5% by weight of a platinum metal.

In some embodiments the metal alloy comprises at least about 0.001%, 0.005%, 0.01 %, 0.05%, 0.1%, 0.5%, 1 %, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% by weight of a group IB metal.

In some embodiments the metal alloy comprises at least about 0.001 %, 0.005%, 0.01 %, 0.05%, 0.1 %, 0.5%, 1 %, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% by weight of an additional alloying element.

In some embodiments the metal alloy comprises at least about 0.001 %, 0.005%, 0.01 %, 0.05%, 0.1 %, 0.5%, 1 %, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% by weight of iron meteorite. In some embodiments the metal alloy comprises

• about 95% to about 99% by weight platinum metal, and about 0.5% to about 5% of a group IB metal, and about 0.001% to about 5% of an additional alloying element, or

· about 97% to about 98% by weight platinum metal, and about 0.5% to about 5% of a group IB metal, and about 0.001% to about 5% of an additional alloying element, or

• about 95% to about 99% by weight platinum metal, and about 1 % to about 3% of a group IB metal, and about 0.001 % to about 5% of an additional alloying element, or

• about 97% to about 98% by weight platinum metal, and about 1% to about 3% of a group IB metal, and about 0.001 % to about 5% of an additional alloying element, or

• about 95% to about 99% by weight platinum metal, and about 0.5IP

ownership agreement to about 5% of a group IB metal, and about 0.001 % to about 1.5% of an additional alloying element, or

• about 97% to about 98% by weight platinum metal, and about 0.5% to about 5% of a group IB metal, and about 0.001% to about 1.5% of an additional alloying element, or

· about 97% to about 98% by weight platinum metal, and about 1% to about 3% of a group IB metal, and about 0.001% to about 1.5% of an additional alloying element, or

• about 95% to about 99% by weight platinum metal, and about 1 % to about 3% of a group IB metal, and about 0.001% to about 1.5% of an additional alloying element.

In some embodiments the platinum metal is palladium. In some embodiments the metal alloy comprises at least about 95%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99% or 99.5% by weight of palladium.

In some embodiments the group IB metal is selected from gold, silver and copper. Preferably the group IB metal is silver. In some embodiments the meteorite comprises iron and nickel.

In some embodiments the metal alloy has improved castability.

In some embodiments the metal alloy has improved resistance to porosity.

In some embodiments the metal alloy has improved resistance to shrinkage.

In some embodiments the metal alloy has improved workability. As used herein the term "workability" or its grammatical equivalents and derivatives means any one or more of cutting, rolling, drawing and soldering. Preferably the term workability refers to each of cutting, rolling, drawing and soldering.

In some embodiments the metal alloy has improved ductility.

In some embodiments the metal alloy has improved soldering properties.

Preferably the improved soldering properties relate to improved thermal conductivity and heat capacity.

In some embodiments the metal alloy has improved remelting.

In some embodiments the metal alloy has improved electrical conductivity.

In a further aspect the invention relates to a metal alloy for the production of jewellery.

In a further aspect the invention relates to a method of manufacture of a metal alloy comprising the following steps: a. combining about 95% to about 99% platinum metal, about 1.5% to about 4% of a group IB metal, and about 0.001 % to about 5% of an additional alloying element selected from the group consisting of: iron, nickel, and a combination of iron and nickel;

b. heating the combination from step (a) to a temperature of between 1600 °C and 1800 °C until molten and blended; and

c. allowing the blend from step (b) to cool until solid.

In some embodiments the method of manufacture of a metal alloy also comprises the pre-step of:

• grinding the additional alloying element into small particles.

In a further aspect the invention relates to a method of manufacturing a metal alloy as described above.

In a further aspect the invention relates to the use of a metal alloy comprising from about 95% to about 99% platinum metal, about 1 .5% to about 4% of a group IB metal, and about 0.001 % to about 5% of an additional alloying element selected from the group consisting of: iron, nickel, and a combination of iron and nickel.

The following embodiments may relate to any of the above aspects. Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings.

It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1 , 1.1 , 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which:

Figure 1a shows an optical micrograph view of the microstructure of the preferred embodiment of the present invention in the form of a metal alloy when cold worked;

Figure 1b shows another optical micrograph view of the microstructure of the preferred embodiment shown in Figure 1 when the alloy is annealed at 800 degrees Celsius for 2 hours;

Figure 2 shows a composition diagram of the bulk material measured by an energy dispersive X-ray analyser;

Figure 3a shows a close up view of the optical micrograph of Figure 1a; Figure 3b shows an energy dispersive X-ray spectrograph of location 002 shown in Figure 3a;

Figure 4 shows the results of a single scan potentiodynamic polarisation corrosion test for Tafel Fit; and Figure 5 shows a cyclic polarisation curve.

BEST MODES FOR CARRYING OUT THE INVENTION

The invention relates to a metal alloy that has a composition consisting essentially of a palladium metal, a group IB metal, and iron meteorite.

In one aspect the invention relates to a metal alloy comprising from about 95% to about 99% platinum metal, about 1.5% to about 4% of a group IB metal, and about 0.001% to about 5% of an additional alloying element selected from iron, nickel, and a combination of iron and nickel.

In a further aspect the invention relates to a metal alloy having a composition consisting essentially of a platinum metal, a group IB metal and an additional alloying element selected from iron, nickel, or a combination of iron and nickel.

In a further aspect the invention relates to a metal alloy comprising from about 95% to about 99% platinum metal, about 1.5% to about 4% of a group IB metal and about 0.001% to about 5% iron meteorite.

In a further aspect the invention relates to a metal alloy consisting essentially of about 95% to about 99% palladium metal, about 1.5% to about 4% of a group IB metal and about 0.001% to about 5% of an additional alloying element selected from iron, nickel, and a combination of iron and nickel.

The preferred metal alloy more specifically comprises about 95% to 99% of a platinum metal, about 1 % to about 4% of a group IB metal and approximately 0.001 to 0.1 % of an additional alloying element selected from iron, nickel, or a combination of iron and nickel. In some embodiments the group IB metal is selected from gold, silver or copper.

The invention relates to a metal alloy that incorporates a high composition of platinum metals such as palladiums. The alloy is substantially resistant to cracking when worked and is substantially free from pitting. An additional advantage is the metal alloy is resistant to tarnishing. The invention relates to the composition of this metal alloy and its manufacture and uses.

The qualities of the alloy of are of particular use, but not limited to, the jewellery industry. It is envisaged the metal alloy will have further application to manufacturing, construction and various research fields, or other applications such as fuel cell technologies or other areas where electrical charge conductivity is required.

The applicants most preferred composition is about 97.5% palladium, about 1.5% silver and about 1 % meteorite by weight to produce the alloy according to the most preferred embodiment of the invention. However, it will be appreciated by those skilled in the art that the exact percentages may be altered by the addition of other alloys and the presence of minor impurities without departing from the scope of the present invention..

Another composition according to another embodiment of the invention has about 97% palladium, about 2% silver and about 1 % meteorite to produce the alloy having equally good casting properties, and fabrication properties that are also good. Another composition according to another embodiment of the invention has about 96.5% palladium, about 2% silver and about 1.5% meteorite to produce an alloy that has good casting qualities. The proportion of silver and meteorite can be varied up to 3.5% in concentration whilst retaining the preferred properties of the metal alloy.

In some embodiments the metal alloy comprises at least about 95%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99% or 99.5% by weight of a platinum metal, and useful ranges may be selected between any of those values, (for example, about 95% to about 100%, about 95.5% to about 100%, about 96% to about 100%, about 96.5% to about 100%, about 97% to about 100%, about 97.5% to about 100%, about 98% to about 100%, about 98.5% to about 100%, about 99% to about 100%, or about 99.5% to about 100% by weight platinum metal).

In some embodiments the metal alloy comprises at least about 95%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99% or 99.5% by weight of palladium, and useful ranges may be selected between any of those values, (for example, about 95% to about 100%, about 95.5% to about 100%, about 96% to about 100%, about 96.5% to about 100%, about 97% to about 100%, about 97.5% to about 100%, about 98% to about 100%, about 98.5% to about 100%, about 99% to about 100%, or about 99.5% to about 100% by weight platinum metal). In some embodiments the metal alloy comprises at least about 0.5%, 1 %, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% by weight of silver, and useful ranges may be selected between any of those values, (for example, about 0.5% to 5%, about 1.5% to 5%, about 2% to 5%, about 2.5% to 5%, about 3% to 5%, about 3.5% to 5%, about 4% to 5%, about 4.5% to 5%, by weight silver). In some embodiments the metal alloy comprises at least about 0.5%, 1 %, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% by weight of iron meteorite, and useful ranges may be selected between any of those values, (for example, about 0.5% to about 5%, about 1.5% to about 5%, about 2% to about 5%, about 2.5% to about 5%, about 3% to about 5%, about 3.5% to about 5%, about 4% to about 5%, about 4.5% to about 5%, by weight iron meteorite).

Examples of a metal alloy useful herein include:

• about 95% to about 99% by weight platinum metal, and about 0.5% to about 5% of a group IB metal, and about 0.001 % to about 5% of an additional alloying element, or

• about 97% to about 98% by weight platinum metal, and about 0.5% to about 5% of a group IB metal, and about 0.001 % to about 5% of an additional alloying element, or

• about 97% to about 98% by weight platinum metal, and about 1 % to about 3% of a group IB metal, and about 0.001 % to about 5% of an additional alloying element, or

• about 95% to about 99% by weight platinum metal, and about 0.5% to about 5% of a group IB metal, and about 0.001 % to about 1.5% of an additional alloying element, or

• about 97% to about 98% by weight platinum metal, and about 0.5% to about 5% of a group IB metal, and about 0.001 % to about 1.5% of an additional alloying element, or

• about 97 to about 98% by weight platinum metal, and about 1% to about 3% of a group IB metal, and about 0.001 % to about 1.5% of an additional alloying element, or

Manufacture

To prepare the metal alloy according to the preferred embodiment of the invention, the constituents of the metal alloy are assembled in their substantially pure form. The desired amount of each constituent is weighed according to the preferred concentration of the alloy. The constituents are heated together to a temperature of approximately 1600 to 1800 °C, or until molten and blended. Once satisfactorily blended, the molten constituents are allowed to cool until solid. In practice, the meteorite is ground into small particles before melted and combined with the other alloying constituents.

Metal alloy properties

The microstructure of the metal alloy according to the preferred embodiment of the invention is shown in Figure 1a, as observed by a Leica D -IRM inverted research microscope equipped with a Zeiss Axiocam digital camera. The shown metal alloy is a single-phase material with an average grain diameter of less than 20 microns. The material was annealed at 800 °C for two hours to produce a new grain structure. The resultant grain structure of the annealed metal alloy is shown in detail in Figure 1b. The annealed metal alloy showed precipitation of a second phase along grain boundaries and inside of the grains, likely to be an oxidation effect. The precipitation is evident only 50 microns distance from the surface and could therefore easily be removed by a polishing away. However, it is envisaged that annealing the metal alloy at lower temperatures than 800°C would likely avoid such oxidation. Figure 2 indicates the major elements present in the metal alloy as measured by a JEOL 7000F field emission scanning electron microscope equipped with an Energy Dispersive X-ray (EDX) Analyzer. Other methods to measure the composition of the metal alloy, such as optical emission spectrometry (OES) could also be used. Although the results indicate the presence of silica, it is believed this was obtained during production of the metal alloy. For example, from the use of silica crucibles typically used for melting and casting metals.

Figures 3a and 3b show the preferred metal alloy being oxygen rich and containing silicon based compounds. However, the silicon content is likely to have been introduced during the manufacturing process. However, the combining of meteorite with other alloying constituents may also be responsible for such compounds being formed.

Palladium and silver metals are mutually soluble. Similarly, palladium and nickel are also mutually soluble. Palladium can further accommodate at least 5 weight percent of iron without forming a second phase. Therefore, the proportions of silver, iron and nickel can be specified in a fairly wide range for the desired metal alloy. Almost no silicon will dissolve in palladium except in superheated liquid so care must be taken to keep the melt temperatures low when producing the preferred alloy composition.

Although the preferred composition of the metal alloy of the present invention is specified, the following elements may also be incorporated into the alloy in low concentrations without substantially affecting the desired properties: gold, platinum, zinc, nickel, copper, iron, chromium, sulphur, phosphorus, calcium, potassium, aluminium, oxygen, and carbon.

The average hardness of the preferred metal alloy is 108.7 Vickers Hardness (HV). Once annealed at 800 °C for two hours, the material hardness is reduced to 86.9 HV. The concentration of silver and other elements such as silicon can be controlled to produce the particular material hardness desired.

A cold rolled sample of the preferred metal alloy has an ultimate tensile strength (UTS) of 405.03 MPa as measured by a uniaxial tensile test. Once annealed at 800 °C for two hours, the UTS is reduced to 284.3 MPa. The particular tensile strength desired can be altered by the concentration of other elements to the metal alloy. The present UTS measurement is indicative of a material that has excellent wear and scratch resistance making it particularly suitable for the jewellery industry.

Compound Amount (g/1)

CaCl₂ 0.28

MgS0₄ 0.06

KC1 0.38

NaCl 5.4

Na₂HP0₄ (anhydrous) 0.122

D-Glucose (C₆H₁₂0₆) 0.9

Sodium BiCarbonate ( aHC0₃) 2.2

HEPES (C₈H₁₈N₂0₄S) 5.96

Phenol Red (C₁₉H₁₄0₅S) 0.011

A sample of the preferred metal of the present invention having a 1 cm² surface area was subjected to a simulated body fluid to represent the salts found in the human body. The following table shows the solution composition used for testing corrosion. The solution was buffered with HEPES to a pH of 7.4±0.05 and was held at a temperature of 37°C±0.5. Electrochemical tests were carried out in a three- electrode cell using a platinum counter electrode (surface area > 2x the working electrode) and a saturated calomel electrode (SCE) was used as a reference. The Open Circuit Potential (OCP) was observed to settle after about 10 minutes in the solution. Polarization tests were conducted 20 minutes after immersion to ensure sufficient settling time.

Figure 4 shows a single scan polarization test in solution. By fitting a Tafel slope to the curve, the calculated corrosion current density is 8.311 μΑ/cm² when no external voltage is applied. The corrosion rate is very low, approximately 0.024 millimeters per year. The following values indicate the corrosion values extracted from the Tafel fit: Ecorr = -61.368 mV vs. Ref; lcorr = 8.311 μΑ; beta c = 207.0 mV; beta a = 211.6 mV; density = 12.020 g/cm3; surface area = 1.000 cm²; corrosion rate = 0.027 487 7 mmpy.

Figure 5 shows a cyclic polarisation from -0/300V to 1.3V and negative hysteresis. That is, the corrosion current density is lower on the reverse scan than it is on the forward scan. Negative hysteresis is indicative of the passive film having the ability to repair itself when damaged and remain passive. This advantageously prevents the material from pitting due to a thin, tightly bound and stable oxide film over the alloy.

Therefore a new metal alloy has been presented that has advantages of increased tensile strength, resistance to tarnishing and corrosion. In addition, the alloying of palladium with meteorite has been successfully demonstrated.

Solidification of molten metal in complex geometrical shapes with varying section thicknesses creates conditions under which internal porosity may form. The impact of internal porosity on properties is caused by the reduction in effective area by pore volume fraction and by stress concentrations at voids leading to premature failure. Porosity can be caused by the precipitation of constituents from liquid solution or by shrinkage during solidification, and more usually by a combination of these effects. There are other sources of internal voids. Mould reactions, high- temperature oxidation, blowholes, and entrapped gas result in defects that adversely affect mechanical properties as well as physical acceptability. Non- metallic inclusions entrained before solidification influence porosity formation and mechanical properties.

A result showing a reduced porosity in a fresh casting of the preferred metal alloy over other known palladium alloys is indicative of a metal having advantageous properties as a metal suitable for industries such as the jewellery industry. Ductility is a desired property for many metal alloys. Ductility can be tested by subjecting a sample to bending forces across a range of temperatures. A more ductile alloy will bend before it breaks. A result showing an increased ductility in a fresh casting of the preferred metal alloy over other known palladium alloys is indicative of a metal having advantageous properties as a metal suitable for industries such as the jewellery industry.

Thermal conductance of a metal alloy is desired to be low for metal used by the jewellery industry. In this way, a localised area of a metal alloy can be welded or soldered, for example, without melting adjacent areas. Thermal conductivity can be measured, for example, by measuring a change in temperature at one end of a length of metal alloy when heat is applied to another end. A result showing a reduced thermal conductance and heat capacity in a fresh casting of the preferred metal alloy over other known palladium alloys is indicative of a metal having advantageous properties as a metal suitable for the jewellery industry.

Another advantageous property of the metal for use in the jewellery industry is the workability of the metal. That is, how easy to cut, roll, draw and solder the metal is. A sample of the metal alloy was prepared according to the preferred embodiments of invention having about 97.5% palladium, about 1.5% silver and about 0.5% iron meteorite by weight.

The metal alloy sample showed increased ductility over other metal alloys used in the jewellery industry by resisting breakage after being subjected to bending forces that would cause other metals to fatigue. The metal alloy of the present invention also appeared to be free from casting flaws such as porosity by exhibiting a clean and consistent cross section when cut. When cut, the metal alloy sample also produced a clean edge. The metal alloy sample also showed excellent thermal conductivity characteristics in that a localised area of the metal alloy could be soldered to without melting immediately adjacent areas.

The metal alloy of the present invention has therefore shown improved workability characteristics over other metal alloys commonly used in the jewellery industry or known in the prior art thereby making it a desirable metal alloy. Where in the foregoing description reference has been made to elements or integers having known equivalents, then such equivalents are included as if they were individually set forth.

Thus preferred embodiments of the present invention have a number of

advantages over the prior art which can include: · improved has improved castability;

• improved resistance to porosity;

• improved resistance to shrinkage and workability;

• improved ductility;

• improved soldering properties such as thermal conductivity and heat

capacity; • improved remelting; and

• improved electrical conductivity.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims

WHAT WE CLAIM IS:

1. A metal alloy comprising from about 95% to about 99% platinum metal, about 1.5% to about 4% of a group IB metal, and about 0.001% to about 5% of an additional alloying element selected from the group consisting of: iron, nickel, and a combination of iron and nickel.

2. The metal alloy as claimed in claim 1 wherein the additional alloying element is iron meteorite.

3. The metal alloy as claimed in claim 1 or claim 2 wherein the metal alloy comprises at least about 95%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99% or 99.5% by weight of a platinum metal.

4. The metal alloy as claimed in any one of claims 1 to 3 wherein the metal alloy comprises at least about 0.001 %, 0.005%, 0.01 %, 0.05%, 0.1 %, 0.5%, 1 %, 1 .5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% by weight of a group IB metal.

5. The metal alloy as claimed in any one of claims 1 to 4 wherein the metal alloy comprises at least about 0.001 %, 0.005%, 0.01 %, 0.05%, 0.1 %, 0.5%, 1 %, 1 .5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% by weight of an additional alloying element.

6. The metal alloy as claimed in claim 5 wherein the metal alloy comprises at least about 0.001 %, 0.005%, 0.01 %, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% by weight of iron meteorite.

7. The metal alloy as claimed in any one of claims 1 to 6 wherein the metal alloy comprises

• about 95% to about 99% by weight platinum metal, and about 0.5% to about 5% of a group IB metal, and about 0.001% to about 5% of an additional alloying element, or • about 97% to about 98% by weight platinum metal, and about 0.5% to about 5% of a group IB metal, and about 0.001 % to about 5% of an additional alloying element, or

• about 95% to about 99% by weight platinum metal, and about 1% to about 3% of a group IB metal, and about 0.001 % to about 5% of an additional alloying element, or

• about 97% to about 98% by weight platinum metal, and about 1% to about 3% of a group IB metal, and about 0.001 % to about 1.5% of an additional alloying element, or

• about 95% to about 99% by weight platinum metal, and about 1% to about 3% of a group IB metal, and about 0.001% to about 1.5% of an additional alloying element.

8. The metal alloy as claimed in any one of claims 1 to 7 wherein the platinum metal is palladium.

9. The metal alloy as claimed in claim 8 wherein the metal alloy comprises at least about 95%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99% or 99.5% by weight of palladium.

10. The metal alloy as claimed in any one of claims 1 to 9 wherein the group IB metal is selected from gold, silver and copper.

1 1. The metal alloy as claimed in claim 10 wherein the group IB metal is silver.

12. The metal alloy as claimed in claim 2 wherein the meteorite comprises iron and nickel.

13. The metal alloy as claimed in any one of claims 1 to 12 wherein the metal alloy is used for the production of jewellery.

13. A metal alloy consisting of about 95% to about 99% platinum, about 1.5% to about 4% of a silver, and about 0.001 % to about 5% of iron meteorite.

14. A method of manufacture of a metal alloy comprising the following steps: a. combining about 95% to about 99% platinum metal, about 1.5% to about 4% of a group IB metal, and about 0.001% to about 5% of an additional alloying element selected from the group consisting of: iron, nickel, and a combination of iron and nickel;

c. allowing the blend from step (b) to cool until solid.

15. The method of manufacture of a metal alloy as claimed in claim 14 wherein the method also comprises the pre-step of:

• grinding the additional alloying element into small particles.

16. The use of a metal alloy comprising from about 95% to about 99% platinum metal, about 1.5% to about 4% of a group IB metal, and about 0.001 % to about 5% of an additional alloying element selected from the group consisting of: iron, nickel, and a combination of iron and nickel.