TWI632242B - Iridium-platinum alloy and machined article made thereof - Google Patents

Abstract

The present invention relates to an iridium-platinum alloy that contains platinum in an amount of 70 wt% or less, the remainder is iridium and unavoidable impurities, and the average particle width to height ratio is at least 5.

Description

Iridium platinum alloy and its processed articles

The invention relates to an iridium-platinum alloy and a processed object manufactured by the same.

Iridium is a platinum group metal. Its hardness and melting point are extremely high. In addition, iridium is one of the second most dense elements (after rhenium) and the most corrosion-resistant metal. Due to these attributes, iridium and iridium-containing alloys are materials of interest for several applications, such as spinning heads, spark plugs, balance wheels, and jewelry.

WO 2011/034566 describes a jewellery article made of a metal containing at least 75 wt% iridium.

US 2005/0129960 A1 describes an alloy composition containing 1 to 10 atomic% of Zr and / or Hf, the balance being iridium; and an article coated with the alloy composition.

EP 2 281 905 A1 describes an iridium-based metal composition that does not contain Zr and Hf and contains 0.5 to 30 wt-ppm boron and 0.5 to 20 wt-ppm calcium.

CN 101483319 A describes an iridium platinum alloy and its use as a spark plug electrode material.

US 2006/0270924 A1 describes an electrode for medical applications comprising a substrate coated with a porous Pt-Ir alloy.

However, because of its hardness, brittleness and high melting point, iridium is extremely difficult to process and shape. Or forged.

The melting point can be reduced by adding platinum to obtain a platinum-iridium alloy. In detail, however, in the case where these alloys are iridium-based (Ir content is more than 50 wt%), they are still extremely brittle and hard materials, and therefore still extremely difficult to process.

If shaped articles are made by processing (such as milling) from a molded body made of extremely hard and brittle materials, the articles typically exhibit surface defects. In detail, the material may break along the edges created during the machining process. However, for many applications, processed objects with such surface defects (eg, edge defects) are not acceptable.

The object of the present invention is to provide an iridium-containing alloy which has improved forgeability and is suitable for preparing shaped articles by processing. If the structure of the shaped object contains edges, the number and size of defects along these edges (for example, due to broken materials) should be kept as low as possible.

This goal is solved by an iridium-platinum alloy, which contains 70% by weight or less of platinum, the remainder is iridium and unavoidable impurities, and the average particle width to height ratio is at least 5.

Figure 1 shows an optical image of an etched microsection.

Figure 2 shows an optical image of an etched microsection.

The shape of the particles can be indicated by the ratio of particle width to height. If the width and height are connected Close to 1, the particles have a relatively "round" shape, while a width to height ratio much higher than 1 indicates an elongated particle shape. In other words, the higher the aspect ratio, the more slender the particles. Typically, if a material has been subjected to a recrystallization process, it contains a large number of equiaxed particles or can even be composed of such particles (ie, particles with a width to height ratio close to 1).

In the present invention, it has been unexpectedly achieved that a molded body (made of an iridium platinum alloy having elongated particles such that the average particle width to height ratio is at least 5) can be processed into an article having a reduced number of surface defects. In detail, the number and size of edge defects can be significantly reduced.

Preferably, the average particle width to height ratio is at least 8, more preferably at least 10. In a preferred embodiment, the average particle width to height ratio is in the range from 5 to 25, more preferably from 8 to 20, even more preferably from 10 to 16.

Preferably, the iridium platinum alloy contains platinum in an amount of 50 wt% or less, more preferably 45 wt% or less. In a preferred embodiment, the iridium-platinum alloy contains platinum in an amount of from 70% to 25% by weight, more preferably from 50% to 25% by weight, and even more preferably from 45% to 25% by weight.

As indicated above, the alloy consists of iridium, platinum, and unavoidable impurities. By using iridium with high purity (for example, at least 99.9% purity, more preferably at least 99.99%) and platinum with high purity (for example, at least 99.9% purity, more preferably at least 99.99%) as The starting material can keep the amount of inevitable impurities in the final Ir-Pt alloy to a very low content. Preferably, the iridium-platinum alloy contains less than 200 wt-ppm of rhodium. More preferably, the iridium-platinum alloy contains less than 200 wt-ppm rhodium, less than 150 wt-ppm copper, less than 100 wt-ppm calcium, less than 50 wt-ppm boron, and less than 100 wt-ppm iron.

Preferably, the average number of pores per μm ² of the iridium-platinum alloy is less than 0.04, and more preferably less than 0.03.

Preferably, the hardness of the iridium platinum alloy is 500 HV1 or less, and more preferably 480 HV1 or less.

As will be discussed in further detail below, the iridium platinum alloy of the present invention is preferably prepared by a method in which the Ir-Pt cast body is subjected to one or more forming steps such as rolling or forging. Therefore, it is preferable that the iridium-platinum alloy is a shaped iridium-platinum alloy, in particular, a rolled or forged iridium-platinum alloy. The shaped iridium-platinum alloy can be a disc or a plate. However, other shapes are possible.

In addition, the present invention relates to a method for preparing an iridium-platinum alloy, the method comprising (i) preparing a casting body of an iridium-platinum melt composed of free iridium, platinum and unavoidable impurities, (ii) Pre-heating the cast body and subjecting the pre-heated cast body to one or more forming steps such that the recrystallization degree of the formed iridium-platinum alloy is less than 30%.

Typically, the casting step (i) includes melting iridium and platinum metal in a boiler (eg, an induction boiler) to prepare an iridium platinum melt and then casting the melt into a mold. The melt consists of iridium and platinum and unavoidable impurities. Preferably, the iridium platinum melt contains platinum in an amount of 70 wt% or less, more preferably 50 wt% or less, even more preferably 45 wt% or less. In a preferred embodiment, the iridium platinum melt contains platinum in an amount of from 70% to 25% by weight, more preferably from 50% to 25% by weight, and even more preferably from 45% to 25% by weight.

Optionally, cool (eg, water-cool) the mold. It may be preferable that the mold is composed of a material having high thermal conductivity (for example, at least 200 W / (m * K) or at least 300 W / (m * K) at 20 ° C), such as copper. A preferred mold is, for example, a water-cooled copper mold.

As known to those skilled in the art, heat treatment can be carried out above the recrystallization temperature. Recrystallization (static recrystallization) to achieve recrystallization, as appropriate, combined with forming (for example, rolling) treatment (dynamic recrystallization). Generally, those skilled in the art are aware of parameters that affect the recrystallization temperature. The degree of recrystallization depends especially on the processing temperature (ie, above or below the recrystallization temperature) and the duration of the processing.

In the method of the present invention, the pre-heating and subsequent forming (for example, rolling) steps are performed under conditions such that the degree of recrystallization of the finally obtained (for example, rolling) iridium-platinum alloy is less than 30%. As explained further below, the degree of recrystallization indicates the relative area (in%) of microsections covered by recrystallized isometric particles.

Based on common sense, those skilled in the art can identify appropriate processing conditions for step (ii) to ensure that the resulting formed (eg, rolled) iridium-platinum alloy has a recrystallization degree of less than 30%. By way of example only, the shaping of the casting body (e.g., rolling) may be performed at a temperature low enough to keep recrystallization to a very low level or even below the recrystallization temperature. In principle, it is also possible that one or more forming steps are performed at least partly at a forming temperature above the recrystallization temperature, but the duration of these forming steps at a temperature above the recrystallization temperature is maintained Short enough to avoid any substantial recrystallization.

In a preferred embodiment, the recrystallization degree of the formed iridium-platinum alloy is less than 20%, more preferably less than 10%, even more preferably less than 5%.

Preferably, at least the final forming step is performed at a forming temperature T _f which is lower than the recrystallization temperature T _rc of the iridium-platinum alloy. More preferably, each forming step is performed at a forming temperature lower than the recrystallization temperature of the iridium platinum alloy. Alternatively, it is also possible that one or more forming steps other than the final forming step are performed at a forming temperature higher than the recrystallization temperature, but the duration of these forming steps is kept short enough to avoid any Substantial recrystallization. As known to those skilled in the art, the recrystallization temperature is the temperature (typically 1 hour) at which recrystallization can be accomplished within a commercially achievable time.

In a preferred embodiment, T _f is at least 300 ° C., more preferably at least 400 ° C., and even more preferably at least 500 ° C., but lower than the recrystallization temperature T _{rc of the} iridium-platinum alloy.

Preferably, the casting body is pre-heated at a temperature T _ph lower than the recrystallization temperature T _rc of the iridium-platinum alloy. In a preferred embodiment, T _ph is at least 300 ° C, more preferably at least 400 ° C, and even more preferably at least 500 ° C, but lower than the recrystallization temperature T _{rc of the} iridium-platinum alloy. The heating time at T _ph can vary over a wide range. Pre-heating the casting body at T _ph may be performed, for example, for 5 to 120 minutes or 10 to 90 minutes.

Those skilled in the art know suitable forming methods. Preferably, the forming of step (ii) is rolling, forging or a combination of the two.

Preferably, step (ii) comprises two or more forming steps, for example, 6 to 30 forming steps, more preferably 10 to 26 forming steps.

Preferably, each forming step is performed at a forming rate of less than 4.0 s ^-1 , more preferably less than 3.0 s ^-1 , and / or a forming degree of less than 10.0%, more preferably less than 8.0%.

As known to those skilled in the art, the forming rate can be determined by the following formula

Where n is the rotation speed of the roll, H ₀ is the thickness of the sample before the rolling step, r '= r / 100; r: the decrease in the thickness of the sample during the rolling step, and R is the roll radius.

The degree of forming corresponds to a reduction in the thickness (in%) of the sample caused by the forming process.

The overall formability may be at least 50%, for example, and more preferably at least 65%.

If step (ii) includes two or more forming steps, it may be preferable to reheat the casting body after at least one of these forming steps in order to prevent the iridium-platinum alloy from forming (e.g., rolling) ) Excessive cooling during processing. Typically, for reheating in the middle of the two forming steps, the iridium platinum alloy is transferred from the forming (e.g., rolling) device to an oven and reheated in an oven to a temperature that is preferably lower than that of the iridium platinum alloy as explained above The temperature of the recrystallization temperature, and then transferred to the forming apparatus in order to continue the forming process. The reheating time can vary over a wide range. The reheating of the casting body may be performed, for example, for 0.5 minutes to 20 minutes or 1 minute to 10 minutes. Depending on the size of the casting body, reheating may be performed after at least 50% of the forming step, and more preferably after each forming step except the final forming step.

In a preferred embodiment, the iridium platinum melt consisting of iridium, platinum, and unavoidable impurities contains from 70% to 25% by weight, more preferably from 50% to 25% by weight, and even more preferably from 45% to 25% by weight. Amount of platinum; pre-heat the casting body to a temperature T _ph from 500 ° C to less than 1350 ° C, more preferably from 800 ° C to less than 1300 ° C, even more preferably from 1000 ° C to less than 1250 ° C; and one or The multiple forming steps are performed at a temperature T _f from 500 ° C to less than 1350 ° C, more preferably from 800 ° C to less than 1300 ° C, and even more preferably from 1000 ° C to less than 1250 ° C.

Preferably, the iridium platinum alloy prepared by the method of the present invention corresponds to the iridium platinum alloy described above (ie, the average particle width to height ratio is at least 5). Therefore, it is preferable that the iridium-platinum alloy contains platinum in an amount of 70% by weight or less, and the remainder is iridium and inevitable impurities. Quality, and the average particle width to height ratio is at least 5. For other preferred properties of the iridium-platinum alloy, reference may be made to the statements provided above.

In addition, the present invention relates to a processed article containing an iridium-platinum alloy and having a density of at least 21.4 g / cm ³ .

Preferably, the processed object is any other part or component of a balance wheel or a clock mechanism. It may also be a jewelry part.

The balance wheel is used in clocks and is sometimes called a rotor. Typically, the balance wheel or rotor is a semi-circular disc that rotates freely, with each movement of the hands of the clock automatically winding the main spring. Its own weight returns it to an upright position.

Preferably, the iridium-platinum alloy of the processed object is composed of iridium, platinum, and unavoidable impurities.

Preferably, the density of the processed object (more specifically, the balance wheel) is at least 21.6 g / cm ³ , and more preferably at least 21.8 g / cm ³ .

Preferably, at least 70 wt%, more preferably at least 80 wt%, even more preferably at least 90 wt% of the balance wheel is composed of an iridium-platinum alloy. Optimally, the balance wheel is composed of an iridium-platinum alloy.

Preferably, the iridium-platinum alloy is composed of iridium, platinum, and unavoidable impurities, and contains not more than 50% by weight of platinum, more preferably not more than 45% by weight of platinum. In a preferred embodiment, the iridium-platinum alloy of the balance contains from 50 wt% to 0.011 wt%, more preferably from 45 wt% to 5 wt%, even more preferably from 45 wt% to 15 wt%, or from 45 wt% to 25 wt. % Of platinum.

Preferably, the iridium-platinum alloy of the balance wheel corresponds to the iridium-platinum alloy described above (ie, the average particle width to height ratio is at least 5). Therefore, it is preferable that the iridium-platinum alloy contains platinum in an amount of 70 wt% or less, and the remainder is iridium and unavoidable impurities, and the average particle width is The degree to height ratio is at least 5. For other preferred properties of the iridium-platinum alloy, reference may be made to the statements provided above.

In addition, the present invention relates to a method for preparing a processed article, the method comprising -The preparation of iridium-platinum alloy by the method described above, -Machining iridium platinum alloy.

Preferably, the processed object is a balance wheel. Typically, processing includes milling. Additionally or alternatively, machining may include drilling, turning, or other commonly known machining steps.

Further, the present invention relates to a clock including the balance wheel described above.

In addition, the present invention relates to the use of the iridium-platinum alloy described above for preparing a processed object (more specifically, a balance wheel).

Measurement method

The parameters referenced in the present invention are determined as follows:

Preparation of microsections for microstructural analysis

Microsections were taken perpendicular to the rolling surface and in (ie, parallel to) the rolling direction. The material was embedded into the epoxy under vacuum. Grind and polish the surface to be analyzed. For grinding, Struers' wet grinder Labo-Pol-25 was used in eight grinding steps (120, 320, 500, 800, 1200, 1500, 2400, and 4000) at 200 rpm. LaboPol-5 (250 rpm) by Struers with a fineness of up to 1 μm (diamond polishing paste) was used for polishing. Subsequently, the samples were electrolytically etched with 20% KCN.

Average particle width to height ratio

The average ratio of particle width to particle height of the sample is determined as follows: As already mentioned above, if the sample is rolled, the microsection is taken perpendicular to the surface of the rolled sample and parallel to the rolling direction. If a rolling step is performed on the sample surface and the rolling direction is changed, a microsection is prepared in the rolling direction of the final rolling step. Select at least two subsections on the microsection, each subsection containing at least 40 particles. For each particle, a light microscope (Olympus PMG3) with a scale is used to determine its width (i.e., its maximum dimension in the rolling direction) and its height (i.e., its maximum dimension perpendicular to the rolling direction) . For each particle, the ratio of particle width to particle height is determined. Finally, based on the ratio of individual particles, the average particle width to height ratio is determined as the arithmetic average.

Average recrystallization

Microsections were prepared as described above, that is, perpendicular to the surface of the rolled sample and in the rolling direction. Select at least two subsections on the microsection, each subsection containing at least 40 particles. For each sub-segment, the relative area (in%) covered by the recrystallized (ie, isometric) particles is determined. The relative area covered by the recrystallized particles can be determined via image analysis software. Those particles having a particle width to height ratio of 0.75 to 1.25 are considered as recrystallized particles. Finally, based on the value of the sub-segment, the average recrystallization degree is determined as the arithmetic mean.

Number of ² holes per μm

In the case of using a light microscope (500x magnification), the number of holes on a region of 50x50 μm ² was counted and then converted to the number of ² holes per 1 μm. In general, this operation is performed for 10 different areas on the microsection, and the average number of holes is calculated as an arithmetic mean.

density

Density is determined via buoyancy according to Archimedes' principle. The weight of the sample was measured with a Mettler Toledo balance SB23001 DeltaRange. Next, determine the weight of the sample in water. Determine the amount of water absorbed by weighing the wet sample. To calculate the sample density, it is assumed that the density of water at 22.5 ° C is 0.99791 g / cm ³ . Calculate the density as follows: density (g / cm ³ ) = 0.99791 (g / cm ³ ) x (SW _dry / (SW _wet -SW _water ))

SW _dry is the weight of the dry sample (in g), SW _wet is the weight of the wet sample (in g), and SW _water is the weight of the sample in water.

hardness

The hardness of the ground sample was determined using a device Zwick Roell ZHμ under a load of HV1.

Amount of impurities

The amount of impurities was determined by using a glow discharge lamp (GDL) of the GD Profiler HR device of Horiba-Jobin-Yvon. Excitation of the sample is achieved by sputtering and an emission spectrum is obtained. The amount of impurities in the ppm range was determined by comparing the intensity of the emission line with a calibrated standard.

Examples

In the following examples, iridium-platinum alloys having different average particle width to height ratios were prepared. From these Ir-Pt alloys, a balance wheel is prepared by grinding, and defects of these processed objects are detected at the edges thereof.

Invention Example 1 (IE1): Ir-Pt alloy, Pt content: 40wt%

A suitable amount of iridium (3N purity) and platinum (3N purity) for obtaining an Ir-Pt alloy with a Pt content of 40 wt% was melted under an argon at 2200 ° C in an induction boiler using a ZrO ₂ crucible. The iridium platinum melt was cast into a water-cooled copper mold. After solidification, an iridium platinum cast body was obtained. The casting body is removed from the mold, and the casting wrinkles on its surface are removed by grinding.

The casting body was pre-heated in an oven at 1200 ° C for 30 minutes in an air atmosphere. Next, the pre-heated cast body was subjected to 19 rolling steps. After each rolling step, in addition to the final rolling step, the casting body is transferred from the rolling press to an oven, heated at a temperature of 1200 ° C for about 5 minutes, and then transferred to the rolling press for further processing. Next rolling step.

The thickness of the casting body before the rolling process and after each rolling step, as well as the thickness reduction (in mm and%), and the forming rate of each rolling step are listed in Table 1 below.

As known to those skilled in the art, the forming rate can be determined by the following formula

Where n is the rotation speed of the roll, H ₀ is the thickness of the sample before the rolling step, r '= r / 100; r: the decrease in the thickness of the sample during the rolling step, and R is the radius of the roll.

The rotation speed of the roll is 22 rpm, and the roll radius is 155 mm.

After the final rolling step, a board of 220x50x3mm was obtained. An etched microsection was prepared perpendicular to the surface of the rolled sample. An optical image of the etched microsection is shown in FIG. 1.

The average particle width to height ratio of the Ir / Pt40 alloy is 12.5. The number of holes is 0.01 per μm ² . The pore size values are well below 5 μm. The degree of recrystallization is extremely low (well below 30%).

Impurities are present in low amounts: Rh <200wt-ppm, Cu <150wt-ppm, Ca <100wt-ppm, B <50wt-ppm, and Fe <100ppm.

The sample had a hardness of 475 HV1 and a density of 22.0 g / cm ³ .

The cast body composed of Ir / Pt40 alloy was processed into a balance wheel by milling. Detect edges of milled objects for defects> 10μm. However, no defects were detected.

Comparative Example 1 (CE1): Ir-Pt alloy, Pt content: 40wt%

A suitable amount of iridium (3N purity) and platinum (3N purity) for obtaining an Ir-Pt alloy with a Pt content of 40 wt% was melted under an argon at 2200 ° C in an induction boiler using a ZrO ₂ crucible. The iridium platinum melt was cast into a water-cooled copper mold. After solidification, an iridium-platinum casting body was obtained. The casting body is removed from the mold, and the casting wrinkles on its surface are removed by grinding.

The cast body was heated in an oven at 1400 ° C. for 30 minutes in an air atmosphere. Next, the heated cast body was subjected to 19 rolling steps. After each rolling step, in addition to the final rolling step, the casting body was heated at a temperature of 1400 ° C for about 4 minutes. Except for the higher temperature, the rolling conditions are the same as the rolling conditions of Inventive Example 1. So cast The thickness of the body before the rolling process and after each rolling step, and the thickness reduction (in mm and%) and the forming rate of each rolling step correspond to those listed in Table 1 above They.

After the final rolling step, a board of 220x50x3mm was obtained. An etched microsection was prepared perpendicular to the surface of the rolled sample. An optical image of the etched microsection is shown in FIG. 2.

CE1's Ir / Pt40 alloy is a mixture of particles with a width to height ratio close to 1 and slightly elongated particles with a width to height ratio of up to 5. Therefore, the average particle width to height ratio is much lower than 5. The number of holes was 0.05 per μm ² . A considerable degree of recrystallization greater than 30% was detected.

Similar to Invention Example 1, impurities are present in low amounts: Rh <200wt-ppm, Cu <150wt-ppm, Ca <100wt-ppm, B <50wt-ppm, and Fe <100ppm.

The sample of CE1 has a hardness of 485HV1 and a density of 22.0g / cm ³ .

Under the same processing conditions as those used in Invention Example 1, the cast body made of the Ir / Pt40 alloy of CE1 was processed into a balance wheel by milling. Detect defects where the size of the edge of the milled object is> 10 μm. A considerable number of such larger-sized edge defects are detected.

Table 2 summarizes the results of Inventive Example 1 and Comparative Example 1.

As demonstrated in the examples, a molded body made of an iridium-platinum alloy with elongated particles can be processed into an article having a reduced number of surface defects. In detail, the number and size of edge defects can be significantly reduced.

Claims (31)

An iridium-platinum alloy containing platinum in an amount of 70% by weight or less, the balance of which is iridium and unavoidable impurities, and the average particle width to height ratio is at least 5. For example, the iridium-platinum alloy according to item 1 of the patent application range, wherein the average particle width to height ratio is in a range from 5 to 25; and / or the iridium-platinum alloy contains platinum in an amount from 70 to 25% by weight. For example, the iridium-platinum alloy according to item 2 of the patent application range, wherein the average particle width to height ratio is in the range from 8 to 20. For example, the iridium-platinum alloy in item 2 of the patent application range, wherein the average particle width to height ratio is in the range from 10 to 16. For example, the iridium-platinum alloy according to item 2 of the patent application range, wherein the iridium-platinum alloy contains platinum in an amount ranging from 50% by weight to 25% by weight. For example, the iridium-platinum alloy according to item 2 of the patent application range, wherein the iridium-platinum alloy contains platinum in an amount of from 45% to 25% by weight. For example, the iridium-platinum alloy according to any one of the items 1 to 6 of the patent application range, the average number of holes per μm ² is less than 0.04; and / or the hardness is 500 HV1 or less. For example, the iridium-platinum alloy according to item 7 of the scope of patent application, the average number of pores per μm ² is less than 0.04; and / or the hardness is 480HV1 or less. For example, the iridium-platinum alloy in any one of the items 1 to 6 of the patent application scope contains less than 200wt-ppm rhodium, less than 150wt-ppm copper, less than 100wt-ppm calcium, less than 50wt-ppm boron, and Fe less than 100 wt-ppm. For example, the iridium-platinum alloy according to any one of claims 1 to 6 of the patent application scope is a rolled or forged iridium-platinum alloy. For example, the iridium-platinum alloy of item 10 of the scope of patent application is a rolled or forged iridium-platinum alloy with the shape of a disc or a plate. A method for preparing an iridium-platinum alloy according to any one of claims 1 to 11 of the scope of patent application, which comprises (i) an iridium-platinum melt composed of free iridium, platinum and unavoidable impurities to prepare a casting body, (ii) Pre-heating the casting body and subjecting the pre-heating casting body to one or more forming steps such that the recrystallization degree of the shaped iridium-platinum alloy is less than 30%. For example, the method of claim 12 wherein at least the final forming step is performed at a forming temperature T _f below the recrystallization temperature; and / or wherein the pre-heating of the casting body is at a temperature below the recrystallization temperature _Performed at T _ph . For example, the method of claim 12 or 13, wherein the casting body is preheated to a temperature T _ph from 500 ° C to less than 1350 ° C; and the one or more forming steps are performed from 500 ° C to less than 1350 It is carried out at a temperature T _f of ° C. For example, the method of claim 14 in which the casting body is pre-heated to a temperature T _ph from 800 ° C to less than 1300 ° C. For example, the method according to item 14 of the patent application range, wherein the casting body is preheated to a temperature T _ph from 1000 ° C to less than 1250 ° C. For example, the method of claim 14 in the patent application range, wherein the one or more forming steps are performed at a temperature T _f from 800 ° C to less than 1300 ° C. For example, the method of claim 14 in the patent application range, wherein the one or more forming steps are performed at a temperature T _f from 1000 ° C to less than 1250 ° C. For example, the method of claim 12 or 13, wherein the forming of step (ii) is rolling or forging or a combination thereof; and / or step (ii) includes two or more forming steps. For example, the method of claim 19, wherein step (ii) includes 6 to 30 forming steps. For example, the method of claim 12 or 13, in which each forming step is performed at a forming rate of less than 4.0s ^-11 and / or a forming degree of less than 10.0%. For example, the method of claim 21 in the patent scope, wherein each forming step is performed at a forming rate of less than 3.0s ^-1 . For example, the method of claim 21 in the patent scope, wherein each forming step is performed at a forming degree of less than 8.0%. A processed article containing the iridium-platinum alloy according to any one of claims 1 to 11 and having a density of at least 21.4 g / cm ³ . For example, the processed article under the scope of patent application No. 24 is a balance wheel. For example, if a processed object is applied for item 24 or 25 of the patent scope, at least 80% by weight of the processed object is made of the iridium platinum alloy; and / or the iridium platinum alloy is composed of iridium, platinum, and unavoidable impurities and Contains no more than 50% by weight of platinum. For example, at least 90% by weight of the processed article of the scope of patent application is made of the iridium platinum alloy. For example, the processed article under the scope of application for patent No. 26, wherein the iridium-platinum alloy is composed of iridium, platinum, and unavoidable impurities, and contains not more than 45% by weight of platinum. For example, the processed article of the scope of patent application No. 24 or 25, wherein the iridium-platinum alloy is the iridium-platinum alloy according to any one of the scope of patent application No. 1 to 11. A method for preparing a processed article, comprising subjecting the iridium-platinum alloy to processing by preparing a method such as any one of items 12 to 23 of the scope of patent application. For example, the method for preparing a processed article according to item 30 of the application, wherein the processing is milling.