Pt alloy for medical applications, and medical member comprising said pt alloy for medical applications

Abstract

The present invention is a Pt alloy for medical applications, which contains a metal element M1 and a metal element M2 in specified ranges. The metal element M1 is at least one metal element selected from among Ru, Rh, Pd, Ag, W, Re, Ir, and Au, and the metal element M2 is at least one metal element selected from among Ti, Zr, Nb, Mo, Hf, and Ta. The Pt alloy according to the present invention has a composition in which, when the concentration of Pt is X, the concentration of the metal element M1 is Y, and the concentration of the metal element M2 is Z, then all of X, Y, and Z are positioned within the range of a prescribed region shown in an X-Y-Z pseudoternary phase diagram. The Pt alloy for medical applications according to the present invention has biocompatibility, X-ray visibility, and the like, and also has good mechanical properties and workability. The Pt alloy for medical applications according to the present invention is applied to medical tools such as embolic coils, guide wires, stents, and catheters by being made into a Pt alloy wire material or a medical member of another form.

Description

Medical-grade Pt alloy and medical components made from said medical-grade Pt alloy

[0001] This invention relates to medical-grade Pt alloys that constitute components of various medical devices. In particular, it relates to medical-grade Pt alloys that have superior mechanical properties compared to conventional medical-grade Pt alloys, as well as good biocompatibility, X-ray visibility, and processability.

[0002] Medical materials that make up medical devices such as embolization coils, guidewires, stents, and catheters require various properties, including mechanical properties such as strength and springiness, chemical stability to ensure biocompatibility, and processability. For example, embolization coils are medical devices that are placed inside blood vessels to prevent the rupture of cerebral aneurysms in the treatment of cerebrovascular disorders such as subarachnoid hemorrhage. Guidewires are medical devices used to guide catheters during catheter treatment, and stents are medical devices that expand tubular parts such as blood vessels from the inside of the lumen. The medical materials that make up these medical devices require high strength (tensile strength) and springiness (elastic limit and elastic elongation limit) so that they can withstand the stress received from pulsating blood vessels and move while repeatedly deforming within curved blood vessels.

[0003] Furthermore, since the medical devices mentioned above come into direct contact with the human body and are sometimes implanted inside the body, biocompatibility is required for the medical materials. In addition, since embolization coils and guide wires are manufactured by coiling extremely thin metal wires into a coil shape, processability must also be considered when selecting their constituent materials.

[0004] As medical materials being considered for application to various medical devices, various alloys such as stainless steel, Ni-Ti alloy, Pt alloy, Pd alloy, etc. are known, and currently stainless steel and Ni-Ti alloy are widely used in actual applications. Also, research on various alloys as medical materials is progressing. For example, Patent Document 1 describes a wire for medical devices made of a Pt alloy of a ternary system or more of the Pt-Ni system. In this prior art, it is a Pt alloy containing 18 to 27% by mass of Ni in Pt and a total of 2 to 7.0% by mass of additive elements (at least any one or more of Ir, Pd, Rh, Ru, Nb, Mo, Re, W, and Ta). Also, Patent Document 2 discloses a medical alloy made of a Pd-based alloy. This prior art clarifies the applicability of a Pd-based multi-component alloy obtained by adding at least any one or more of B and Re, Ru, Ir, Pt, W, Au, Zr, Co, Ni, and Ta to Pd to a medical alloy.

[0005] Japanese Patent Application Laid-Open No. 2022-501502 Japanese Patent Application Laid-Open No. 2008-500452

[0006] Among the above-mentioned conventional medical materials, stainless steel and Ni-Ti alloy with usage records are good in mechanical properties such as tensile strength and corrosion resistance, but since they are composed of relatively light (low atomic weight) metal elements such as Fe, Cr, Ni, etc., they have insufficient X-ray visibility. In the above-mentioned medical device diagnosis and treatment methods, it is normal to confirm the position of the device while performing X-ray imaging. In particular, for medical devices composed of extremely thin wires, a metal material with X-ray visibility is suitable to avoid overlooking.

[0007] On the other hand, the Pt-Ni-based multi-component alloy and Pd-based alloy of Patent Documents 1 and 2 have good X-ray visibility, but there is room for improvement in mechanical properties. Since medical materials are used in the human body, any abnormal behavior, unexpected damage, or breakage during use must be avoided. For this purpose, the pursuit of higher mechanical properties is required. Also, improvement from the perspective of biocompatibility is necessary for medical materials, and it is also required to ensure chemical stability and not contain elements that induce metal allergies.

[0008] This invention was made against the background described above, and provides an alloy for medical devices that possesses biocompatibility and X-ray visibility, while having better mechanical properties than the prior art and also having good processability. Furthermore, it provides medical components to which these improved medical alloys are applied.

[0009] The inventors decided to develop a medical alloy based on a Pt alloy, in which Pt is the main component, as a solution to the above-mentioned problems. Pt is a metallic element with a large atomic weight, has good X-ray visibility, and is also extremely biocompatible. Therefore, by applying an alloy in which Pt is the main component, these properties can be ensured.

[0010] On the other hand, in order to increase the Pt content in a Pt alloy, the content of alloying elements must be kept low. Therefore, the inventors decided to apply a combination of solid solution strengthening and precipitation strengthening (aging strengthening) as a strengthening mechanism to improve the mechanical properties of Pt alloys. This is based on the idea of ​​improving the mechanical properties of the Pt alloy matrix through solid solution strengthening, and then further strengthening it through precipitation strengthening (aging strengthening).

[0011] The inventors then conducted a detailed study on the types of additive elements and compositional ranges of Pt alloys that are effective in exhibiting both solid solution strengthening and precipitation strengthening (aging strengthening) mechanisms for high-Pt concentration Pt alloys, and arrived at the present invention.

[0012] In other words, the present invention relates to a medical-grade Pt alloy comprising Pt, a metal element M1, a metal element M2, and unavoidable impurities, wherein the metal element M1 is at least one of Ru, Rh, Pd, Ag, W, Re, Ir, and Au, and the metal element M2 is at least one of Ti, Zr, Nb, Mo, Hf, and Ta, and the Pt alloy has a composition in which all of X, Y, and Z are located within the range of a first region represented by a polygon (A1-A2-A3-A4-A5) enclosed by straight lines between the following five points A1, A2, A3, A4, and A5 in the X-Y-Z pseudo-ternary phase diagram, where the concentration of Pt is X, the concentration of metal element M1 is Y, and the concentration of metal element M2 is Z.

[0013] Point A1 (X: 83.26 at%, Y: 16.64 at%, Z: 0.1 at%) Point A2 (X: 86.0 at%, Y: 6.0 at%, Z: 8.0 at%) Point A3 (X: 90.9 at%, Y: 0.1 at%, Z: 9.0 at%) Point A4 (X: 96.4 atomic%, Y: 0.1 atomic%, Z: 3.5 atomic%) A5 point (X: 93.4 atomic%, Y: 6.5 atomic%, Z: 0.1 atomic%)

[0014] The structure of the medical-grade Pt alloy according to the present invention, various medical components made from this medical-grade Pt alloy, and their uses will be described in detail below.

[0015] I. Composition and Properties of the Medical Pt Alloy According to the Present Invention As described above, the medical Pt alloy according to the present invention is composed of a Pt alloy to which metal elements M1 and M2 are added. The Pt alloy according to the present invention has suitable mechanical properties due to the effects of solid solution strengthening and precipitation strengthening, respectively.

[0016] A. Composition of the medical-grade Pt alloy according to the present invention The essential constituent elements of the Pt alloy according to the present invention are Pt, metallic element M1, and metallic element M2. The function of each constituent element and the composition range of the Pt alloy will be explained below.

[0017] A-1. Metal element M1 Metal element M1 is an additive element that improves the strength of the Pt alloy through solid solution strengthening. Metal element M1 is at least one of the following metal elements: Ru, Rh, Pd, Ag, W, Re, Ir, and Au. In the Pt alloy of the present invention, which is based on the premise of a high Pt concentration, the amount of additive element added cannot be increased significantly. The aforementioned additive element can improve the strength of the Pt alloy with a small amount of addition. Furthermore, since these metals have relatively large atomic weights, alloying them with Pt also contributes to ensuring X-ray visibility.

[0018] A-2. Metal element M2 Metal element M2 is an additive element used to improve the strength of Pt alloys through precipitation strengthening (age strengthening). The Pt alloy applied to this invention, upon heat treatment, generates an intermetallic compound between Pt and metal element M2, and precipitation strengthening occurs due to this intermetallic compound. The metal element M2 that exhibits this strengthening mechanism is at least one of the following metal elements: Ti, Zr, Nb, Mo, Hf, and Ta.

[0019] A-3. Pt In the Pt alloy according to the present invention, Pt is the main constituent metallic element of the Pt alloy. As can be seen from the respective concentration ranges of metallic elements M1 and M2 in the alloy composition described later, the Pt alloy of the present invention contains 83.26 atomic percent or more of Pt. In the present invention, by increasing the Pt content, X-ray visibility and biocompatibility are ensured. Furthermore, Pt is a metallic element that contributes to material strengthening because it forms intermetallic compounds with metallic element M2.

[0020] A-4. Concentration range of each constituent metal element (alloy composition of Pt alloy) The alloy composition of the Pt alloy according to the present invention is defined by the X-Y-Z pseudo-ternary phase diagram, where the concentration of Pt is X, the concentration of metal element M1 is Y, and the concentration of metal element M2 is Z. Specifically, in the X-Y-Z pseudo-ternary phase diagram, all of X, Y, and Z are located within the range of the first region represented by the polygon (A1-A2-A3-A4-A5) enclosed by straight lines between the five points A1 (X: 83.26 atomic%, Y: 16.64 atomic%, Z: 0.1 atomic%), A2 (X: 86.0 atomic%, Y: 6.0 atomic%, Z: 8.0 atomic%), A3 (X: 90.9 atomic%, Y: 0.1 atomic%, Z: 9.0 atomic%), A4 (X: 96.4 atomic%, Y: 0.1 atomic%, Z: 3.5 atomic%), and A5 (X: 93.4 atomic%, Y: 6.5 atomic%, Z: 0.1 atomic%). This region also includes the straight lines connecting the five points. Figure 1 shows the X-Y-Z pseudo-ternary phase diagram representing the alloy composition of the Pt alloy in the present invention, as well as points A1, A2, A3, A4, and A5 and the lines enclosing them.

[0021] The effects of each metal element, Pt, metal element M1, and metal element M2, are as described above. The effects of each metal element are mutually and effectively exerted when the concentrations of these metal elements fall within the range of the polygon (A1-A2-A3-A4-A5) in the X-Y-Z pseudo-ternary phase diagram described above. Furthermore, if multiple metal elements are added as metal element M1 from the group described above, the sum of their concentrations is denoted as Y. Similarly, for metal element M2, the sum of the concentrations of the added metal elements is denoted as Z.

[0022] When the concentration of metal M1 (Y) is outside the range of the polygon described above, material strengthening by solid solution strengthening becomes insufficient, or excessive addition diminishes the significance of the present invention, which involves using a high-Pt alloy. Furthermore, when the concentration of metal M2 (Z) is outside the range of the polygon described above, precipitates that can contribute to strength improvement become difficult to form, or excessive addition makes the Pt alloy excessively hard, reducing its workability. When the workability of the Pt alloy decreases, it becomes difficult to process it into wire rods of the dimensions required for various medical devices.

[0023] Preferably, the concentrations (X, Y, Z) of each metal element (Pt, metal element M1, and metal element M2) in the X-Y-Z pseudo-ternary phase diagram are such that all of X, Y, and Z are located within the range of the second region represented by a polygon (B1-A2-A3-A4-B5) enclosed by straight lines between the five points B1 (X: 83.95 atomic%, Y: 13.95 atomic%, Z: 2.1 atomic%), A2 (X: 86.0 atomic%, Y: 6.0 atomic%, Z: 8.0 atomic%), A3 (X: 90.9 atomic%, Y: 0.1 atomic%, Z: 9.0 atomic%), A4 (X: 96.4 atomic%, Y: 0.1 atomic%, Z: 3.5 atomic%), and B5 (X: 95.15 atomic%, Y: 2.75 atomic%, Z: 2.1 atomic%).

[0024] Furthermore, it is preferable that the concentrations (X, Y, Z) of each metal element (Pt, metal element M1, and metal element M2) in the X-Y-Z pseudo-ternary phase diagram fall within the range of a third region represented by a polygon (C1-A2-A3-C4) enclosed by straight lines between the four points C1 (X: 84.85 atomic%, Y: 10.4 atomic%, Z: 4.75 atomic%), A2 (X: 86.0 atomic%, Y: 6.0 atomic%, Z: 8.0 atomic%), A3 (X: 90.9 atomic%, Y: 0.1 atomic%, Z: 9.0 atomic%), and C4 (X: 95.15 atomic%, Y: 0.1 atomic%, Z: 4.75 atomic%).

[0025] Figure 2 shows the X-Y-Z pseudo-ternary phase diagram corresponding to the second region described above, and Figure 3 shows the X-Y-Z pseudo-ternary phase diagram corresponding to the third region. The compositional ranges of these second and third regions limit the range of the first region and are alloy compositions that can suppress the decrease in tensile strength and / or elastic limit before and after aging heat treatment, or increase the tensile strength and / or elastic limit after heat treatment.

[0026] A-5. Inevitable Impurities The Pt alloy according to the present invention is essential for Pt, metal element M1 and metal element M2, and is substantially composed of these metal elements. However, the inclusion of unavoidable impurities is permissible. Unavoidable impurities may include Mg, Al, Si, Ca, Cr, Fe, Ni, Cu, and Sn. The total concentration of unavoidable impurities is preferably 0.5% by mass or less, and more preferably 0.2% by mass or less.

[0027] The method for measuring the concentrations of metallic elements M1, M2, and unavoidable impurities in the Pt alloy according to the present invention, as described above, is not particularly limited. Inductively coupled emission spectrometry (ICP) and inductively coupled plasma mass spectrometry (ICP-MS) are preferred methods for measuring the concentrations of each element. In ICP, the Pt alloy is broken into small pieces as needed, and the solution liquefied with hydrofluoric acid is analyzed using an analytical instrument. ICP is a suitable analytical method when the analyte is in the state of wires or medical components before being incorporated into a medical device, or when it is in a state where it can be extracted as an analytical sample even after being incorporated into a medical device. Other analytical methods that can be applied include instrumental analysis methods such as X-ray fluorescence analysis (XRF), energy-dispersive X-ray analysis (EDX), and wavelength-dispersive X-ray analysis (WDX). Instrumental analysis methods are useful when the analyte is incorporated into a medical device and difficult to separate.

[0028] B. Medical components made of medical-grade Pt alloy according to the present invention. The medical-grade Pt alloy according to the present invention has good processability and can be processed into various types of medical components to construct medical devices.

[0029] B-1. Medical-grade Pt alloy wire The Pt alloy according to the present invention can preferably be made into a Pt alloy wire. Pt alloy wire is a particularly effective use of the Pt alloy according to the present invention, and can be used as a constituent material for medical components such as coils, which will be described later, and the wire itself may also be applied to medical devices. In the Pt alloy wire according to the present invention, the wire diameter is preferably 10 μm or more and 100 μm or less. In medical devices such as embolization coils and guide wires, metal wires with wire diameters within the above range are often used. The cross-sectional shape of the wire is not limited to a perfect circle, and may be elliptical or rectangular. When the cross-sectional shape of the wire is other than a perfect circle, the wire diameter shall be the maximum diameter.

[0030] Furthermore, the Pt alloy wire according to the present invention exhibits excellent mechanical properties as a medical material due to the effects of the metal elements M1 and M2 described above. Mechanical properties required for medical materials include tensile strength (UTS), elongation at break, elastic limit, and elastic limit elongation, which are measured by tensile testing. In addition, the present invention aims for precipitation strengthening by the metal element M2. Precipitation strengthening occurs through heat treatment (aging heat treatment), and at least one of the aforementioned mechanical properties is improved after heat treatment. The mechanical properties of the Pt alloy wire according to the present invention change depending on the processing heat treatment during the manufacturing process and the resulting wire diameter, and are specifically explained below.

[0031] B-1-1. Tensile Strength Tensile strength is the maximum stress until the material breaks under tensile load, and in this invention, ultimate tensile strength (UTS) is applied. Tensile strength is related to the resistance to breakage when secondary processing such as coiling, stranding, and bending is performed on the Pt alloy wire according to the present invention. Furthermore, improving tensile strength contributes to improving the processing yield during the aforementioned processing. In addition, tensile strength is related to the durability when the Pt alloy wire is applied to various medical devices. For these reasons, tensile strength is a particularly important mechanical property for the Pt alloy wire according to the present invention.

[0032] The tensile strength (UTS) of the Pt alloy wire is preferably 1000 MPa or higher. More preferably, the tensile strength of the Pt alloy wire is 1500 MPa or higher. The tensile strength of the Pt alloy wire of the present invention can be adjusted within the above range before and after aging heat treatment. The upper limit of the tensile strength is preferably 3500 MPa or lower. Wires with excessively high tensile strength may have their workability affected.

[0033] B-1-2. Elongation at Break Elongation at break is the elongation rate when material fracture occurs under tensile load, and, like tensile strength, is related to the resistance to fracture and processing yield when processing Pt alloy wire. The elongation at break of Pt alloy wire is preferably 1.5% or more and 6.0% or less. An elongation at break of 2.0% or more is more preferable. The elongation at break of the Pt alloy wire of the present invention can be adjusted within the above range before and after aging heat treatment.

[0034] B-1-3. Elastic Limit The elastic limit is the stress at which elastic deformation occurs without permanent strain, and is related to springiness. As described above, medical devices such as guide wires are often used under intermittent stress in curved paths, and it is required that their dimensional accuracy does not deviate. Therefore, a high elastic limit and excellent springiness are preferable. The elastic limit of Pt alloy wire is preferably 450 MPa or higher, more preferably 700 MPa or higher, and even more preferably 1000 MPa or higher. However, since wires with excessively high elastic limits may result in devices lacking flexibility, the elastic limit of Pt alloy wire is preferably 2500 MPa or lower. The elastic limit of the Pt alloy wire of the present invention can be adjusted within the above range before and after aging heat treatment.

[0035] B-1-4. Elastic elongation Elastic elongation refers to the amount of deformation that can occur within the elastic deformation range and is a characteristic related to the applicability of the wire to various medical devices. The higher the elastic elongation, the better it can follow the complex curved shapes of blood vessels, etc., and the larger the amount of deformation that can be returned to its original shape, thus expanding the range of application to medical devices. The elastic elongation of Pt alloy wire is preferably 0.5% or more, more preferably 0.6% or more, and even more preferably 0.7% or more. The upper limit of the elastic elongation is preferably 1.0% or less. The elastic elongation of the Pt alloy wire of the present invention can be adjusted within the above range before and after aging heat treatment.

[0036] B-1-5. Young's Modulus In addition to the above, Young's modulus is a general indicator of the mechanical properties of metallic materials. The Young's modulus of the Pt alloy wire according to the present invention is preferably 120 GPa or higher, and more preferably 140 GPa or higher. The upper limit of Young's modulus is preferably 170 GPa or lower. The Young's modulus can also be adjusted within the above range before and after aging heat treatment.

[0037] The various mechanical properties described above can be measured by tensile testing of Pt alloy wire. The tensile testing method can be the same as that used for tensile testing of metal wire (for example, tensile testing in accordance with JIS Z 2241 "Tensile Testing Method for Metallic Materials").

[0038] Furthermore, while the mechanical properties of the Pt alloy according to the present invention are generally improved by aging heat treatment, it is not always the case that all of the above-mentioned mechanical properties improve simultaneously. For example, sometimes both tensile strength and elastic limit increase, and sometimes one increases while the other decreases. Also, sometimes elongation increases even while both tensile strength and elastic limit decrease. It is presumed that this behavior is based on the amount and type of metals M1 and M2 (precipitates) and the aging heat treatment conditions (temperature). When applying aging heat treatment to the Pt alloy and Pt alloy wire according to the present invention, it is preferable to adjust the desired mechanical properties within the above range by whether or not aging heat treatment is performed and under what conditions.

[0039] B-2. Pt alloy coils or Pt alloy stranded wires Coils and stranded wires made by coiling or twisting wires made from wires of medical alloys are important medical components that constitute medical devices. The Pt alloy wire according to the present invention is capable of secondary processing and can be made into Pt alloy coils or Pt alloy stranded wires by coiling or twisting. Specifically, Pt alloy stranded wires that will become medical components can be manufactured by twisting together multiple Pt alloy wires. Furthermore, Pt alloy coils for medical devices can be manufactured by coiling single wires or one or more Pt alloy stranded wires. In addition, in such coiling or twisting processes, coils or stranded wires may be made by combining them with wires of materials other than the Pt alloy wire according to the present invention.

[0040] Coils and stranded wires used as medical components are microscopic components manufactured by processing Pt alloy wires with the minute wire diameters described above, for purposes such as movement within the blood vessels of the human body. Considering the wire diameter of the Pt alloy wires described above, the processing rate of coiling using this coil index can be said to be high. The Pt alloy coils and Pt alloy stranded wires according to the present invention remain in a desirable state without surface cracks, etc., even after undergoing such heavy processing.

[0041] B-3. ​​Other Forms of Medical Components The Pt alloy according to the present invention can be used to form medical components in forms other than the wires, coils, and stranded wires described above. For example, pipes or rods. There are no restrictions on the dimensions and shape (cross-sectional shape) of such medical components. These forms of medical components can also acquire the various mechanical properties described above by combining appropriate processing heat treatment and aging heat treatment.

[0042] C. Medical devices equipped with various medical components according to the present invention The medical components made of Pt alloy according to the present invention described above can be components of various medical devices. For example, Pt alloy coils and Pt alloy strands can constitute part or all of medical devices such as embolization coils, guide wires, catheters, and stents. Embolization coils are generally in the shape of a secondary coil. Embolization coils are formed by further coiling the Pt alloy coil of the present invention. Guide wires (spring wires) are manufactured by joining a hollow member (for example, in the shape of a coil) obtained by processing the Pt alloy wire or Pt alloy strand of the present invention with a core (core material) made of an appropriate material. Alternatively, a guide wire may be formed by joining a guide wire core using the Pt alloy wire or Pt alloy strand of the present invention with a hollow member made of an appropriate material. A catheter may have a tube made of resin or the like, and a marker in which the Pt alloy wire or Pt alloy strand of the present invention is wound around the outer circumference of the tube. The embolization coil and guide wire according to the present invention can function stably without being easily damaged, thanks to the favorable mechanical properties of the Pt alloy wire.

[0043] Furthermore, medical components other than Pt alloy wires, Pt alloy coils, and Pt alloy stranded wires can be used as markers for catheters, etc., or as medical devices such as stents. When using medical components made of Pt alloy according to the present invention as medical devices, they can be combined with medical components made of other materials.

[0044] Furthermore, when the Pt alloy according to the present invention is processed into a coil shape or the like and incorporated into a medical device, it is not easy to measure its tensile strength or the like. Therefore, as a method for simply estimating the tensile strength of the Pt alloy constituting a coil or the like, measurement of Vickers hardness can be mentioned. Since Vickers hardness can be measured with a relatively small sample, it can also be applied to coils or the like incorporated into medical devices. And, although there is no perfect match between tensile strength and hardness, there is a certain degree of correlation, so it becomes possible to estimate whether the above-described tensile strength is possessed by hardness measurement.

[0045] The Pt alloy according to the present invention has a hardness of 300 Hv or more and 600 Hv or less in terms of Vickers hardness when it has a tensile strength within the above range after aging heat treatment. Incidentally, regarding the measurement of Vickers hardness, it can generally be measured under known conditions using a Vickers hardness tester or a micro-Vickers hardness tester. For example, it can be measured by a method according to JIS Z 2244 "Vickers hardness test - Test method".

[0046] II. Method for manufacturing a medical Pt alloy and various medical members according to the present invention The Pt alloy according to the present invention can be manufactured by obtaining an ingot of the Pt alloy by general melting and casting. The Pt alloy ingot can be manufactured by mixing Pt and the metal elements M1 and M2 so as to have the above-described composition and casting by arc melting, vacuum melting, or the like. The shape of this alloy ingot is not particularly limited, such as a rod shape or a plate shape.

[0047] And a medical member can be obtained by plastic working (cold working) the Pt alloy ingot. Hot working may be performed between the production of the Pt alloy ingot and the plastic working. The hot working process is a process for breaking the cast structure of the alloy ingot. Also, by the hot working process, the cross-sectional area of the alloy ingot can be reduced to dimensions suitable for cold working. In the hot working process, hot swaging, hot forging, and hot rolling (hot grooving rolling) are performed. These hot workings may be performed multiple times. The processing temperature in the hot working process is preferably 600°C or more and 1500°C or less.

[0048] Also, when performing hot working in the present invention, it is preferable to perform hot working with a cross-sectional reduction rate of 50% or more before and after processing. This is to break the as-cast structure and further homogenize the material structure, which can improve the workability in cold working and promote homogenization by solution treatment before aging heat treatment.

[0049] The Pt alloy ingot that has been hot-worked as necessary becomes a medical member of a desired size through a cold working process. In the cold working process, cold rolling (cold grooving rolling), cold wire drawing, cold drawing, cold extrusion, etc. are performed. These cold working processes can be combined and cold working can be performed multiple times. The processing temperature in the cold working process is preferably from room temperature to 100°C. A processing temperature that is too high may cause age hardening.

[0050] In the processing of Pt alloy wire, the cold working process can be performed multiple times to obtain the target wire diameter. The processing rate in one cold working process is preferably 5% or more and 25% or less. Also, annealing treatment for ensuring workability may be performed during the cold working process. The annealing temperature is preferably 700°C or more and 1300°C or less. By going through the above cold working process, a Pt alloy wire of the target wire diameter can be obtained.

[0051] Regarding the manufacture of medical members other than Pt alloy wire, the Pt alloy coil and Pt alloy stranded wire are coiled and stranded as described above. For other forms of medical members, they are processed by the above plastic processing, cutting processing, grinding processing, etc. until they reach the desired shape and size.

[0052] The Pt alloy wire or medical member that has reached the desired size (wire diameter) and shape can adjust its mechanical properties by precipitation strengthening through aging heat treatment. The aging heat treatment preferably has a heating temperature of 300°C or more and 900°C or less. Also, the heat treatment time is preferably 1 to 24 hours. As the timing of performing aging heat treatment (including the following solution treatment), for example, in the case of a Pt alloy wire, it is preferably performed after secondary processing such as coiling because the workability is high before precipitation strengthening. However, performing aging heat treatment before secondary processing is not prohibited.

[0053] Furthermore, solution treatment and cold working may be performed before the aging heat treatment for precipitation strengthening. Solution treatment and cold working homogenize the Pt alloy, allowing precipitates (intermetallic compounds) to precipitate in a suitable dispersion state. Solution treatment is a process in which the Pt alloy is heated to a temperature range of 1000°C to 1500°C, and then rapidly cooled. The heating time at this time is preferably 1 to 24 hours. Rapid cooling is preferably done with water. However, in the production of Pt alloy wire according to the present invention, solution treatment is optional, and aging heat treatment may be performed without solution treatment.

[0054] As described above, the medical Pt alloy according to the present invention consists of a high-concentration Pt alloy, and its mechanical properties are improved by the addition of appropriate amounts of metal elements M1 and M2. Furthermore, the high Pt alloy provides good X-ray visibility and biocompatibility. Medical components made of the Pt alloy according to the present invention exhibit suitable properties as components of medical devices such as embolization coils, guide wires, stents, and catheters.

[0055] A diagram showing an X-Y-Z pseudo-ternary phase diagram for explaining the structure of the Pt alloy according to the present invention, and a polygon (A1-A2-A3-A4-A5) indicating the range of alloy composition in the first region. A diagram showing an X-Y-Z pseudo-ternary phase diagram for explaining the structure of the Pt alloy according to the present invention, and a polygon (B1-A2-A3-A4-B5) indicating the range of alloy composition in the second region. A diagram showing an X-Y-Z pseudo-ternary phase diagram for explaining the structure of the Pt alloy according to the present invention, and a polygon (C1-A2-A3-C4) indicating the range of alloy composition in the third region. A diagram plotting the alloy compositions of the Pt alloy and Pt alloy wire manufactured in this embodiment on an X-Y-Z pseudo-ternary phase diagram. A diagram explaining a method for evaluating the resilience of a coil body manufactured from Pt alloy wire. A CT photograph taken for X-ray visibility evaluation of a coil body manufactured from Pt alloy wire. A schematic side view showing one embodiment of the guide wire of the present invention. A schematic side view showing another embodiment of the guide wire of the present invention.

[0056] First Embodiment: Embodiments of the present invention will be described below. In this embodiment, a Pt alloy was manufactured by adding metal element M1 (Re, Ir) and metal element M2 (Ti, Zr, Nb, Mo, Hf, Ta) to Pt. A Pt alloy was also manufactured by adding metal element M1 (Re) and metal elements not corresponding to metal element M2 (V, Cr, Mn, Fe, Co, Ni: hereinafter referred to as metal element M'). Then, various Pt alloys were processed into Pt alloy wires and their mechanical properties were measured.

[0057] [Manufacturing of Pt Alloy] Pt ingots (purity 99.98 mass%), metal ingots of metal elements M1 (Re, Ir), metal elements M2 (Ti, Zr, Nb, Mo, Hf, Ta), and metal elements M' (V, Cr, Mn, Fe, Co, Ni) (purity 99.9 mass%) were prepared, and these were weighed and mixed to various compositions and arc-melted to produce a master alloy. This master alloy was then vacuum-melted to produce round bar-shaped Pt alloy ingots (diameter 10 mm).

[0058] [Processing into Pt Alloy Wire] The rod-shaped ingots of various Pt alloys manufactured as described above were processed into rough wires by a hot working process. In the hot working process, the rod-shaped Pt alloy ingots were heated at 1100°C for 10 minutes, and then formed into rough wires with a diameter of 5 mm by hot swaging (total reduction ratio of 50% or more).

[0059] The rough wire produced in the hot working process was cold groove rolling and cold drawing at room temperature to a diameter of φ1.0 mm. After the wire was manufactured, samples of various lengths were cut for measurement and evaluation.

[0060] [Evaluation of Mechanical Properties of Pt Alloy Wires] Tensile tests were performed on the various Pt alloy wires manufactured as described above before aging heat treatment to measure tensile strength (UTS), elastic limit, elongation at break, and elastic limit elongation. For the tensile tests, wires were cut to a length of 150 mm as measurement samples and tested using a tensile testing machine (Autograph AGS-X, Shimadzu Corporation). The test conditions were a gauge length of 100 mm and a crosshead speed of 10 mm / min.

[0061] Furthermore, the workability of various wire rods before aging heat treatment was evaluated. In the workability evaluation, those that could be processed into wire rods (wire diameter 1 mm) without fracture or surface cracking during the multiple cold working processes described above were judged as passable (○). On the other hand, Pt alloys that cracked or fractured during the cold working process were judged as failing in workability (×). Tensile tests were not performed on the Pt alloy wire rods that failed the workability evaluation.

[0062] Then, various Pt alloy wires were subjected to aging heat treatment. The aging heat treatment was carried out by heating and holding at 300 to 700°C for 1 hour. Tensile tests were performed on the Pt alloy wires after aging heat treatment using the same method and conditions as above, and the tensile strength, elastic limit, elongation at break, elastic limit elongation, and Young's modulus were measured.

[0063] Tables 1 and 2 show the results of evaluating the processability and mechanical properties of Pt alloy wires manufactured to confirm the effects of adding metal elements M1 and M2 in this embodiment. The composition of each Pt alloy wire listed in Tables 1 and 2 is based on the amount of each element added when the Pt alloy was melted and cast, and this composition was consistent with the composition obtained by ICP analysis of the Pt alloy wire. In this embodiment, the mechanical properties of metal wires that constitute embolization coils and guide wires currently used in medical settings were referenced, and each Pt alloy wire was evaluated with the following acceptance criteria: tensile strength: 1000 MPa or more, elastic limit: 550 MPa or more, elongation at break: 1% or more, elastic limit elongation: 0.45% or more, and Young's modulus: 110 GPa or more. The heat treatment (HT) temperatures listed in Tables 1 and 2 are the heat treatment temperatures at which each characteristic value showed a large fluctuation range before and after heat treatment.

[0064]

[0065]

[0066] Figure 4 shows the X-Y-Z pseudo-ternary phase diagrams representing the compositions of the Pt alloys constituting the various Pt alloy wires examined in this embodiment, as shown in Tables 1 and 2. In Figure 4, the Pt concentration is represented by X, the concentration of metal element M1 (Re, Ir) by Y, and the concentration of metal element M2 (Ti, Zr, Nb, Mo, Hf, Ta) by Z. As can be seen from Tables 1 and 2 and Figure 4, Pt alloy wires made from Pt alloys where the concentrations X, Y, and Z of each constituent metal element are within the region (first region) indicated by the polygon (A1-A2-A3-A4) in the X-Y-Z pseudo-ternary phase diagram exhibit excellent tensile strength and elastic limit, which are the main mechanical properties (No. 2-6, No. 8-21, No. 23-24, No. 28-35, No. 37-38, No. 40, No. 42-45). In particular, regarding tensile strength, these Pt alloy wires, with the exception of No. 2, have a high tensile strength of 1300 MPa or more even at the post-processing stage (before aging heat treatment).

[0067] Furthermore, Pt alloy wires containing metallic elements M1 and M2 undergo heat treatment for aging, which increases at least one of their tensile strength, elastic limit, or Young's modulus. The Pt alloy wires after this aging treatment also tend to show improvements in fracture elongation and elastic limit elongation. It has been confirmed that the Pt alloy wires in this embodiment exhibit desirable mechanical properties.

[0068] In this embodiment, the effects of metal elements M1 and M2 on the Pt alloy wire rods are confirmed. First, referring to No. 1 and No. 2, which have the same concentration of metal element M1 (Re) but differ in the presence or absence of metal element M2 (Zr), it can be said that the tensile strength can be increased and made suitable even with the addition of metal element M1 alone. Furthermore, the addition of metal element M2 shows a further improvement in tensile strength. However, even in Pt alloy wire rods containing both metal elements M1 and M2, Pt alloys containing an excess of metal element M2 (Zr) and having a composition outside the range of the first region of the polygon (A1-A2-A3-A4) have poor workability and cannot be processed into wire rods (No. 25 to No. 27, No. 36, No. 39, No. 41). Regarding metal element M2, although increasing the amount added has a continuous effect of improving mechanical properties, the upper limit of its addition amount should be considered from the viewpoint of workability.

[0069] Furthermore, as mentioned above, metal element M1 alone can be expected to improve mechanical properties to some extent. This can be confirmed from sources other than the comparison between No. 1 and No. 2. For example, referring to Nos. 6 to 8 and Nos. 21 to 22, which have the same or similar concentrations of metal element M2 (Zr) but differ in the presence or absence of metal element M1 (Re), these studies also show an improvement in mechanical properties due to the addition of metal element M1. Considering the properties of metal element M2, the technical significance of adding metal element M1 is clearer. That is, metal element M2 is a metal element whose excessive addition should be avoided from the standpoint of workability. Metal element M1 can be said to have the effect of further boosting mechanical properties after the addition of metal element M2, which has limitations on the amount that can be added. However, adding too much of the metal element M1 can lead to a decrease in Pt concentration, potentially affecting corrosion resistance and X-ray visibility. Therefore, an upper limit should be set on the amount of metal element M1 added.

[0070] The above comparative studies were conducted on Pt alloy wires (Nos. 2-6, 8-21, 23-27) to which Re was added as metal element M1 and Zr as metal element M2. However, other metal elements besides Re and Zr are also effective as metal elements M1 and M2 (Nos. 28-44). It was confirmed that Pt alloy wires to which both metal elements M1 and M2 are added are preferable.

[0071] Tables 1 and 2 also show the changes in tensile strength and elastic limit (ΔUTS, Δelastic limit) before and after heat treatment. In this embodiment, Pt alloy wires having compositions within the first region may experience a decrease in tensile strength before and after heat treatment, depending on the alloy composition. However, considering that Pt alloy wires within the first region still meet the acceptance criteria even with a decrease in tensile strength, this phenomenon itself does not pose a major problem. Furthermore, within the second region, the decrease in tensile strength is reduced to 40 MPa or less, and in some cases, the tensile strength even increases (No. 5-6, No. 8, No. 10-11, No. 13-14, No. 19-20, No. 28, No. 31, No. 43, No. 45). Furthermore, the Pt alloy wires within the third region showed an increased increase in tensile strength due to heat treatment, with almost all exhibiting a strength increase of 75 MPa or more (No. 9, 12, 15-18, No. 21, No. 32-35, No. 37-38, No. 44). Although no increase in strength was observed after heat treatment for Pt alloy wire No. 38, which is within the third region, the elastic limit clearly increased. Considering these results, it can be said that the alloy composition of Pt alloy wires can be determined by considering the specifications of the medical device to which they are applied and whether or not an increase in tensile strength after heat treatment is necessary.

[0072] Furthermore, in this embodiment, we also evaluated Pt alloy wires to which metal element M' (V, Cr, Mn, Fe, Co, Ni) that does not correspond to metal element M2 is added along with metal element M1 (Re). The evaluation results of the processability and mechanical properties of these Pt alloy wires are shown in Table 3.

[0073]

[0074] Table 3 confirms that adding metal element M' (V, Cr, Mn, Fe, Co, Ni) along with metal element M1 (Re) does not significantly improve mechanical properties (Nos. 46-52). This invention aims to further improve the strength of a Pt alloy by solid solution strengthening with metal element M1 and then adding precipitation strengthening with metal element M2. Compared to a Pt alloy with only metal element M1 (Re) added (No. 1), it can be said that adding metal element M' does not provide the same strength-improving effect as metal element M2.

[0075] [Confirmation of suitability for medical devices] From the results of the evaluation tests described above, it was confirmed that the Pt alloy wire according to this embodiment has suitable mechanical properties for use as a medical wire. Next, the Pt alloy wire was processed into a stranded wire, and then the stranded wire was processed into a coil to confirm its applicability to medical devices. Specifically, the resilience and X-ray visibility of the coil were evaluated.

[0076] Medical devices such as guidewires, which are operated within the blood vessels of the human body, must have resilience to deformation caused by contact with the inner wall of the blood vessel or passing through the affected area or lesion. If the resilience of the medical component is low, plastic deformation occurs during deformation, which can lead to a decrease in the performance of the device. In the evaluation of resilience in this embodiment, a coil body was subjected to stress loading and bent deformation, and then its shape was checked when the stress was released. This evaluation method allows for the evaluation of the resistance to plastic deformation and the ability to restore to the original shape. Figure 5 is a diagram illustrating the schematic of the evaluation method for the resilience of a coil body. In the evaluation test of this embodiment, a straight coil body was bent to 180° so that both ends were in contact, and the residual angle was measured when the stress was released. At this time, the value obtained by the formula (180 (°) - residual angle (°)) / 180 (°) was defined as the recovery rate (%). The higher this recovery rate, the more difficult it is to undergo plastic deformation and the better the resilience.

[0077] In this embodiment, Pt alloy wires were used as samples, with Re as the metal element M1 and Zr and Ti as the metal elements M2 (No. 6 in Table 1 (Pt-6.5Re-4.2Zr) and No. 33 in Table 2 (Pt-6.5Re-6Ti)). In the evaluation test, multiple strands of Pt alloy wire manufactured in the same manner as above were used to form a twisted wire, and the twisted wire was wound around a core metal and coiled to form a coil. The coil was then heat-treated (heat treatment temperature approximately 700°C). The recovery test (Figure 5) was performed on each coil made from the manufactured Pt alloy wire. Three tests were performed on each sample, and the mean value and standard deviation (σ) were calculated, with the mean value being the recovery rate (%). The results of this recovery evaluation are shown in Table 4. Table 4 also shows the test results for a coil made from commercially available medical wire (PtNi alloy) processed in the same manner as above.

[0078]

[0079] Table 4 shows that the Pt alloy wires (Pt-6.5Re-4.2Zr, Pt-6.5Re-6Ti) according to this embodiment have a higher recovery rate than commercially available medical wires. Therefore, from the viewpoint of recovery, the Pt alloy wires according to this embodiment can be said to be applicable to medical devices such as guide wires.

[0080] Next, the X-ray visibility of the same Pt ​​alloy wires (Pt-6.5Re-4.2Zr, Pt-6.5Re-6Ti) as described above was confirmed. In the visibility confirmation test, as above, stranded Pt alloys of each composition were used as the observation target, and the X-ray visibility was evaluated by imaging using an X-ray CT scanner. At this time, the tube voltage during imaging was set to 57kV, 70kV, and 85kV, and the imaging results at each tube voltage were compared. In this visibility confirmation test as well, the results were compared with stranded wires of commercially available medical wires.

[0081] Figure 6 shows photographs taken when the tube voltage of the X-ray CT scanner was varied. At a tube voltage of 57 kV, all stranded wires were clearly visible, and there was almost no difference in visibility even at a tube voltage of 70 kV. In the photograph taken at a tube voltage of 85 kV, the stranded wire made from commercially available medical wire was extremely difficult to see in its lower half or more. Even with the Pt alloy wire (Pt-6.5Re-4.2Zr, Pt-6.5Re-6Ti) stranded wire of this embodiment, the image is fainter, but the entire wire is still visible. From this, it can be said that the Pt alloy wire of this embodiment has higher X-ray visibility compared to the conventional technology.

[0082] Regarding the method for determining X-ray visibility, in addition to imaging with the X-ray apparatus described above, measuring the specific gravity of the alloy material using methods such as the Archimedes method is a simple method. In this regard, the specific gravities of the Pt alloy wires of this embodiment, Pt-6.5Re-4.2Zr alloy wire and Pt-6.5Re-6Ti alloy wire, are 20.48 (Pt-6.5Re-4.2Zr alloy) and 20.25 (Pt-6.5Re-6Ti alloy), respectively. In this respect, considering that the specific gravity of stainless steel currently used in guide wires and the like is around 8, it can be seen how superior the X-ray visibility of the Pt alloy of the present invention is.

[0083] Based on the above test results regarding resilience and X-ray visibility, it was confirmed that the Pt alloy wire (Pt-M1-M2 alloy wire) of this embodiment has good applicability to actual medical devices.

[0084] Second Embodiment: In this embodiment and the following third embodiment, an embodiment of a guide wire will be described as an example of a medical device to which the medical Pt alloy of the present invention is applied. The guide wire according to the present invention can be composed of a Pt alloy wire or Pt alloy stranded body made by processing a Pt alloy wire and a core (core shaft) made of appropriate constituent materials. In this case, the guide wire has a core shaft, a Pt alloy coil or Pt alloy stranded body provided on the outer circumference of the core shaft, and a tip fixing portion disposed at the tip of the core shaft. The core shaft may be straight or may have a tapered portion. When the core shaft has a tapered portion, the Pt alloy coil may be arranged so as to cover the tapered portion. By arranging the Pt alloy coil etc. in the tapered portion in this way, it is possible to suppress deformation that tends to occur in the tapered portion.

[0085] Figure 7 is a schematic side view showing one embodiment of the guide wire of the present invention. The guide wire 10 of this embodiment is composed of a core shaft 11, a Pt alloy coil 12, and a tip fixing portion 13.

[0086] The core shaft 11 has a tapered section 14 that gradually decreases in diameter towards the tip, and equal-diameter sections 15a and 15b. The dimensions of the core shaft 11 in the longitudinal direction are typically 1,800 to 3,000 mm in total length and 1 mm to 3 mm in tapered section 14. The outer diameter of the core shaft 11 is typically 0.25 mm to 0.46 mm. Examples of materials used to construct the core shaft 11 include stainless steel and superelastic alloys such as Ni-Ti alloy. The diameter of the Pt alloy wire that constitutes the Pt alloy coil 12 is typically 0.01 to 0.10 mm.

[0087] The tip fixing portion 13 is the part where the tip of the core shaft 11 and the tip of the Pt alloy coil 12 are fixed together, and is formed from brazing material or the like. The rear end of the Pt alloy coil 12 is fixed to the core shaft 11.

[0088] When using the guidewire 10, the guidewire 10 is inserted into the blood vessel from its tip, and the tip of the guidewire 10, which is exposed outside the body, is manipulated to advance it. At this time, the tip of the guidewire 10 may be intentionally curved before insertion into the blood vessel for the purpose of improving maneuverability, etc. Also, the tip of the guidewire 10 may be inadvertently curved while advancing inside the blood vessel. As a result of the curvature of the tip of the guidewire 10, a U-shaped curve may be formed. If the guidewire 10 is pushed in at this time, the U-shape will advance towards the posterior end, but the presence of the tapered portion 14 creates a rigidity gap, which can suppress the advancement of the U-shape. However, at this time, the tapered portion 14 is prone to deformation due to stress concentration.

[0089] In this embodiment, the guidewire 10 has a tapered section 14 covered with a Pt alloy coil 12 that is excellent in durability and resistance to deformation. This suppresses deformation of the tapered section 14. The guidewire 10 of this embodiment can be used continuously even after passing through a lesion in a U-shape without any loss of vascular selectivity.

[0090] Third Embodiment: Figure 8 shows a schematic side view illustrating another embodiment of the guide wire of the present invention. The guide wire 20 of this embodiment is composed of a core shaft 21, a Pt alloy coil 22, and a tip fixing portion 23. The core shaft 21 has tapered portions 24a, 24b, 24c, and 24d that gradually decrease in diameter toward the tip, and equal-diameter portions 25a, 25b, and 25c. The guide wire 20 of this embodiment also has a stranded body 26 that covers the equal-diameter portion 25c and a part of the tapered portion 24d. As the stranded body 26, a stranded body made of stainless steel such as SUS316 can be used. Alternatively, a stranded body made of a superelastic alloy such as Ni-Ti alloy, or a radiopaque metal such as platinum or tungsten may be used. Furthermore, a stranded body of Pt alloy according to the present invention may be used.

[0091] By adopting the above configuration, it is possible to suppress the occurrence of problems such as deformation caused by the rigidity gap in the tapered portion 24c.

[0092] The Pt alloy for medical use according to the present invention has desirable mechanical properties and good processability. The Pt alloy for medical use according to the present invention is useful as a component material for various medical devices. Medical components made of the Pt alloy according to the present invention are particularly expected to be applied to medical devices such as embolization coils, guide wires, stents, and catheters. Explanation of symbols

[0093] 10, 20 Guide wire 11, 21 Core shaft 12, 22 Pt alloy coil 13, 23 Tip fixing part 14, 24a, 24b, 24c, 24d Tapered part 15a, 15b, 25a, 25b, 25c Equal diameter part 26 Stranded wire

Claims

1. A medical-grade Pt alloy comprising Pt, a metal element M1, a metal element M2, and unavoidable impurities, wherein the metal element M1 is at least one of Ru, Rh, Pd, Ag, W, Re, Ir, and Au, and the metal element M2 is at least one of Ti, Zr, Nb, Mo, Hf, and Ta, and the Pt alloy has a composition in which all of X, Y, and Z are located within the range of a first region represented by a polygon (A1-A2-A3-A4-A5) enclosed by straight lines between the following five points A1, A2, A3, A4, and A5 in the X-Y-Z pseudo-ternary phase diagram, where the concentration of Pt is X, the concentration of metal element M1 is Y, and the concentration of metal element M2 is Z. Point A1 (X: 83.26 at%, Y: 16.64 at%, Z: 0.1 at%) Point A2 (X: 86.0 at%, Y: 6.0 at%, Z: 8.0 at%) Point A3 (X: 90.9 at%, Y: 0.1 at%, Z: 9.0 at%) Point A4 (X: 96.4 atomic%, Y: 0.1 atomic%, Z: 3.5 atomic%) A5 point (X: 93.4 atomic%, Y: 6.5 atomic%, Z: 0.1 atomic%) 2. A medical Pt alloy according to claim 1, having a composition in which all of X, Y, and Z are located within the range of a second region represented by a polygon (B1-A2-A3-A4-B5) enclosed by straight lines between the five points B1, A2, A3, A4, and B5 in the X-Y-Z pseudo-ternary phase diagram, where X is the concentration of Pt, Y is the concentration of metal element M1, and Z is the concentration of metal element M2. Point B1 (X: 83.95 at%, Y: 13.95 at%, Z: 2.1 at%) Point A2 (X: 86.0 at%, Y: 6.0 at%, Z: 8.0 at%) Point A3 (X: 90.9 at%, Y: 0.1 at%, Z: 9.0 at%) Point A4 (X: 96.4 at%, Y: 0.1 at%, Z: 3.5 at%) Point B5 (X: 95.15 at%, Y: 2.75 at%, Z: 2.1 at%) 3. A medical Pt alloy according to claim 1, having a composition in which all of X, Y, and Z are located within the range of a third region (C1-A2-A3-C4) formed by drawing straight lines between the following four points C1, A2, A3, and C4 in the X-Y-Z pseudo-ternary phase diagram, where X is the concentration of Pt, Y is the concentration of metal element M1, and Z is the concentration of metal element M2. C1 point (X: 84.85 atomic%, Y: 10.4 atomic%, Z: 4.75 atomic%) A2 point (X: 86.0 atomic%, Y: 6.0 atomic%, Z: 8.0 atomic%) A3 point (X: 90.9 atomic%, Y: 0.1 atomic%, Z: 9.0 atomic%) C4 point (X: 95.15 atomic%, Y: 0.1 atomic%, Z: 4.75 atomic%) 4. A medical Pt alloy wire made of the medical Pt alloy described in claim 1.

5. A medical component comprising a Pt alloy coil formed by coiling the medical Pt alloy wire described in claim 4, or a Pt alloy stranded wire body formed by twisting the medical Pt alloy wire.

6. A pipe-shaped or rod-shaped medical component made of medical-grade Pt alloy as described in claim 1.

7. A medical device comprising a Pt alloy wire as described in claim 4, or at least one of the medical components described in claim 5 or claim 6, wherein the medical device is an embolization coil, a guide wire, a stent, or a catheter.

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