Metallic components, implant components and metallic components for biomedical applications

Abstract

The metal component is a metal component containing 98.8% or more by mass of titanium, and the metal component includes a first region and a second region, the first region being a region within 3 μm from the surface of the metal component and having an alpha titanium content of 10% or more by volume having an alpha phase crystal structure, and the second region being a region 40 μm or more from the surface of the metal component, and having an omega titanium content of 95% or more by volume having an omega phase crystal structure.

Description

[Technical Field]

[0001] The present disclosure relates to a metal member, an implant member, and a biomedical metal member. [Background technology]

[0002] Titanium has a high specific strength and is therefore widely used in the aerospace and automotive industries. In addition, its excellent biocompatibility has led to increased demand for it as a biocompatible metal material for dental implants and other applications.

[0003] The titanium that makes up the titanium materials currently in widespread use is alpha titanium, which has an alpha phase crystal structure. Alpha-pure titanium with a high alpha titanium content has high elongation at break (hereinafter also referred to as ductility), but low tensile strength (hereinafter also referred to as strength). On the other hand, titanium alloys in which other metals are added to titanium have high tensile strength but low elongation at break. As such, with conventional titanium materials primarily composed of alpha titanium, there is a trade-off between strength and ductility, and it has not been possible to obtain a titanium material that combines high strength and high ductility.

[0004] Patent Document 1 discloses that a titanium material containing omega titanium having an omega phase crystal structure can achieve both high strength and high ductility. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2023 / 100603 Summary of the Invention

[0006] The metal member of the present disclosure comprises: A metal member containing 98.8% by mass or more of titanium, the metal member includes a first region and a second region, the first region is a region within 3 μm from the surface of the metal member and having an alpha titanium content of 10% by volume or more having an alpha phase crystal structure, the second region is a region that is 40 μm or more away from the surface of the metal member, The metal member has an omega titanium content of 95% by volume or more, the omega titanium having an omega phase crystal structure in the second region. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view of a metal member according to a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of a high-pressure cell of an ultra-high-pressure and high-temperature generating apparatus used in the production of the metal member of the first embodiment. [Figure 3] FIG. 3 is a schematic diagram showing the basic structure of an implant using the implant member of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Problems to be Solved by the Present Disclosure According to Patent Document 1, the greater the content of omega titanium, which has an omega-phase crystal structure in a titanium material, the more improved its strength and ductility. Therefore, it is presumed that increasing the content of omega titanium in a titanium material is effective from the perspective of improving strength and ductility.

[0009] On the other hand, alpha titanium has a longer history of use than omega titanium, and there is a wealth of information available on surface treatment methods and biocompatibility. From the standpoint of ease of surface treatment and safety when used as a biomaterial, the presence of alpha titanium on the surface of titanium materials is required.

[0010] Therefore, the present disclosure aims to provide metal components, implant components, and biomedical metal components that have a higher omega titanium content than conventional titanium materials that are primarily composed of alpha titanium, and that contain alpha titanium on their surfaces.

[0011] Effects of the present disclosure According to the present disclosure, it is possible to provide metal components, implant components, and biomedical metal components that have a higher omega titanium content than conventional titanium materials that are primarily composed of alpha titanium, and that contain alpha titanium on their surfaces.

[0012] Description of the embodiments of the present disclosure First, embodiments of the present disclosure will be listed and described. (1) The metal member of the present disclosure is A metal member containing 98.8% by mass or more of titanium, the metal member includes a first region and a second region, the first region is a region within 3 μm from the surface of the metal member and having an alpha titanium content of 10% by volume or more having an alpha phase crystal structure, the second region is a region that is 40 μm or more away from the surface of the metal member, The metal member has an omega titanium content of 95% by volume or more, the omega titanium having an omega phase crystal structure in the second region.

[0013] According to the present disclosure, it is possible to provide a metal member that has a higher omega titanium content than conventional titanium materials that are primarily composed of alpha titanium, and that includes alpha titanium on the surface.

[0014] (2) In the above (1), the alpha titanium content in at least a portion of the first region may be 10% by volume or more and less than 50% by volume, which allows at least a portion of the surface of the metal component to have particularly excellent strength, making the metal component suitable for use in applications requiring particularly high strength.

[0015] (3) In the above (1), the content of alpha titanium in at least a portion of the first region may be 50% by volume or more and 100% by volume or less. This makes it easy to apply existing surface treatment methods to metal components, and increases the reliability of the biocompatibility of the metal component, since the content of alpha titanium is high in at least a portion of the surface of the metal component.

[0016] (4) In any of (1) to (3) above, the standard deviation of the alpha titanium content in at least a portion of the first region may be 1.5% or more, thereby allowing regions with a high alpha titanium content and regions with a low alpha titanium content to coexist on the surface of the same metal component depending on the application.

[0017] (5) The implant member of the present disclosure is an implant member made of the metal member described in any one of (1) to (4) above.

[0018] According to this, the implant member has a higher omega-titanium content than conventional implant members made of titanium materials primarily composed of alpha-titanium, and has superior strength and ductility. In addition, because the implant member contains alpha-titanium on the surface, it is easy to treat the surface and is safe for the living body.

[0019] (6) The biomedical metal component of the present disclosure is a biomedical metal component made of the metal component described in any one of (1) to (4) above.

[0020] According to this, the biomedical metal component has a higher omega-titanium content than conventional biomedical metal components made of titanium materials primarily composed of alpha-titanium, and can therefore have superior strength and ductility. Furthermore, because the biomedical metal component contains alpha-titanium on its surface, it is easy to treat the surface and is safe for the living body.

[0021] (7) In the above (6), the biometallic component may be a component for fixing an artificial skull, a component for fixing a spinal device, a component for an implantable device, or a component for a sensor housing.

[0022] (8) In the above (7), the artificial skull fixing member or the spinal device fixing member may be a rod, a plate, or a screw.

[0023] Details of the embodiments of the present disclosure Specific examples of the metal member, implant member, and biomedical metal member of the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0024] In this disclosure, the expression "A to B" means the upper and lower limits of a range (i.e., A or greater and B or less), and if no unit is specified for A and a unit is specified only for B, the units of A and B are the same.

[0025] <Embodiment 1: Metallic member> A metal member according to one embodiment of the present disclosure (hereinafter also referred to as "embodiment 1") comprises: A metal member containing 98.8% by mass or more of titanium, The metal member includes a first region and a second region, the first region is a region within 3 μm from the surface of the metal member and having an alpha titanium content of 10% by volume or more having an alpha phase crystal structure, the second region is a region that is 40 μm or more away from the surface of the metal member, The metal member has an omega titanium content of 95% by volume or more, the omega titanium having an omega phase crystal structure in the second region.

[0026] <Titanium content> The metal member of embodiment 1 contains 98.8% or more by mass of titanium. This gives the metal member high specific strength and excellent biocompatibility. The titanium content of the metal member may be 98.8% to 100% by mass, 98.9% to 100% by mass, 99.0% to 99.99% by mass, 99.2% to 99.99% by mass, 99.3% to 99.99% by mass, or 99.4% to 99.99% by mass.

[0027] The metal member of the first embodiment may be made of titanium and other components other than titanium. The other components may be at least one selected from the group consisting of common transition metal elements (such as scandium (Sc), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), silver (Ag), hafnium (Hf), tantalum (Ta), tungsten (W), platinum (Pt), and gold (Au)) and inevitable impurities such as hydrogen (H), carbon (C), nitrogen (N), and oxygen (O).

[0028] The content of other components in the metal member of embodiment 1 is measured by inductively coupled plasma (ICP) optical emission spectrometry if the other components are transition metal elements, or by secondary ion mass spectrometry (SIMS) if the other components are elements other than transition metal elements, such as hydrogen, carbon, nitrogen, and oxygen.

[0029] The titanium content of the metal member is determined by measuring the content of components other than titanium using the method described above, and subtracting the content of components other than titanium from the metal member, which is taken as 100 mass %.

[0030] <Metal component configuration> Fig. 1 is a cross-sectional view of a metal member of embodiment 1. As shown in Fig. 1, the metal member of embodiment 1 includes a first region and a second region.

[0031] ≪First area≫ In the metal component of the first embodiment, the first region is a region within 3 μm from the surface of the metal component, and has an alpha titanium content of 10% by volume or more having an alpha phase crystal structure. Here, the region within 3 μm from the surface of the metal component can also be expressed as a region sandwiched between the surface of the metal component and a virtual plane that is 3 μm from the surface of the metal component to the interior of the metal component. In FIG. 1, the entire surface of the metal component is made up of the first region, but the first region may also make up a portion of the surface of the metal component.

[0032] In the metal component of embodiment 1, the alpha titanium content of the first region is 10% by volume or more, or may be 10% by volume or more and 100% by volume or less, 20% by volume or more and 100% by volume or less, 40% by volume or more and 100% by volume or less, 60% by volume or more and 100% by volume or less, 80% by volume or more and 100% by volume or less, or may be 100% by volume.

[0033] In the present disclosure, a method for confirming whether a metal member includes a first region is as follows.

[0034] Step A1: Observe the surface of the metal part using a micro X-ray diffraction device (Rigaku Corporation "SmartLab" (trademark)) to identify the area where alpha titanium is present. Measurement conditions are as follows: X-ray used: Cu-Ka; excitation conditions: 45 kV, 200 mA; entrance slit size: 0.8 mm x vertical 0.1 mm; detector: HyPix-3000 (2D); scanning method: 2θ-θ scan; measurement range: 2θ = 25°-90°; step width: 0.03°; scan speed: 0.5° / min. The area where a diffraction peak is observed in the range of 2θ = 39.7°-40.4° is determined to be the area where alpha titanium is present.

[0035] The metal member is cut along the normal to the surface region where alpha titanium is present to expose a cross section. If the surface region does not have a flat region, the cross section is exposed by cutting from any point on the surface region in a direction toward the center of gravity of the metal member. The cross section is then polished to a mirror finish using a cross-section polisher (manufactured by JEOL Ltd.).

[0036] Step B1. The mirror-finished cross section of the metal component is observed using an electron backscatter diffraction (EBSD) device attached to a scanning electron microscope (SEM-EBSD, SEM device: Carl Zeiss "Gemini450" (trademark), EBSD device: Oxford "Symmetry" (trademark). The observation magnification is 1000 to 10000 times. The measurement conditions are an acceleration voltage of 15 kV, a current value of 15 nA, and 0.1 to 0.02 μm / step. EBSD analysis is performed on the obtained observation image.

[0037] Step C1: The EBSD analysis results are subjected to phase analysis using commercially available software (Oxford "AZtecCrystal" (trademark)) to obtain a phase mapping image showing the titanium crystal structure. The titanium crystal structure identified here is the crystal structure observed when the titanium appearing in the cross section of the metal component is viewed in a planar view from the normal direction of the cross section.

[0038] Step D1: In the phase mapping image, a rectangular measurement area measuring 3 μm × 8 μm is set within the region between the surface 23 of the metal component and a virtual line L1 that is 3 μm from the surface 23 to the interior of the metal component 20. The measurement area has a length of 3 μm in the depth direction and a length of 8 μm perpendicular to the depth direction. If the surface of the metal component has irregularities, the line that passes through the position on the surface of the metal component that protrudes most toward the interior of the metal component in the phase mapping image and is perpendicular to the depth direction is considered to be the surface of the metal component. In the present disclosure, the depth direction is the direction perpendicular to the mean line of the surface of the metal component as defined in JIS B 0601-1994 in the phase mapping image. The region between the surface of the metal component and the virtual line L1 in the phase mapping image corresponds to the region of the metal component that is within 3 μm of the surface of the metal component.

[0039] Step E1: Using the above software, measure the percentage of the area of ​​alpha titanium relative to the total area of ​​the measurement region (hereinafter also referred to as "area percentage of alpha titanium").

[0040] Step F1: The above-mentioned alpha titanium area percentage is measured in multiple non-overlapping measurement areas. The multiple measurement areas may be located on the same cross section of the metal component, or may be located on different cross sections. In the present disclosure, if there are five or more measurement areas with an alpha titanium area percentage of 10% by volume or more, the metal component is confirmed to include a first region within 3 μm from the surface of the metal component, in which the content of alpha titanium having an alpha phase crystal structure is 10% by volume or more.

[0041] In the present disclosure, as described in step F1 above, even if there are five or more measurement regions on the same cross section (hereinafter also referred to as the "first cross section") of a metal component where the area percentage of alpha titanium is 10% or more by volume, the metal component is determined to include the first region. In this case, the presence of the first region in a direction perpendicular to the first cross section can be confirmed by the following procedure: A metal component including the first cross section is cut out along a normal to the first cross section so as to pass through the first region in the first cross section, thereby exposing a second cross section. The content of alpha titanium in the measurement region of the second cross section is measured using the same method as steps A1 to F1 above. If the second cross section includes five or more measurement regions where the content of alpha titanium is 10% or more by volume, it is confirmed that the first region is also present in a direction perpendicular to the first cross section.

[0042] Furthermore, in the same metal component, in a region where alpha titanium is present and the results of observation using a micro X-ray diffraction device are similar in procedure A1, it has been confirmed that the alpha titanium content of the first region is nearly the same in multiple different cross sections obtained by cutting the region along the normal line, which indicates that the first region exists extending in the in-plane direction of the surface of the metal component.

[0043] In the present disclosure, if it is confirmed that a metal component contains a first region using the above confirmation method, the surface of the metal component is determined to contain a region in which the alpha titanium content is 10% by volume or more.

[0044] In the metal member of embodiment 1, the first region can contain omega titanium along with alpha titanium. The total content of alpha titanium and omega titanium in the first region can be 95% by volume or more, 98% by volume or more, 99% by volume or more, or even 100% by volume. The first region can also contain beta titanium as long as the effects of the present disclosure are not impaired.

[0045] In the present disclosure, the method for measuring the total content of alpha titanium and omega titanium in the first region is as follows: Using the above-described method for confirming that the metal component contains a first region, ten measurement regions with an alpha titanium area percentage of 10% by volume or more are identified. For each measurement region, the software described above is used to measure the sum of the alpha titanium area percentage and the omega titanium area percentage relative to the total area of ​​the measurement region. The average of the sum of the alpha titanium area percentage and the omega titanium area percentage for the ten measurement regions is calculated. In the present disclosure, this average corresponds to the total content of alpha titanium and omega titanium in the first region.

[0046] In the metal component of embodiment 1, the alpha titanium content in at least a portion of the first region may be 10% by volume or more but less than 50% by volume, or 20% by volume or more but less than 40% by volume. Since at least a portion of the surface of the metal component has an alpha titanium content of less than 50% by volume, excellent strength is easily ensured, making the metal component suitable for applications requiring particularly high strength. Examples of applications include implant components with a diameter of 2 mm to 4 mm. The implant component is suitable for use in, for example, anterior teeth.

[0047] In the present disclosure, the method for confirming that the alpha titanium content in at least a portion of the first region is 10% by volume or more and less than 50% by volume is as follows: The area percentage of alpha titanium is measured in multiple measurement regions using the same method as the method for confirming that the metal component includes a first region described above. In the present disclosure, if there are five or more measurement regions in which the area percentage of alpha titanium is 10% by volume or more and less than 50% by volume, it is confirmed that the alpha titanium content in at least a portion of the first region is 10% by volume or more and less than 50% by volume.

[0048] In the present disclosure, if the above confirmation method confirms that the alpha titanium content in at least a portion of the first region of the metal component is 10% by volume or more and less than 50% by volume, the surface of the metal component is determined to include a region in which the alpha titanium content is 10% by volume or more and less than 50% by volume.

[0049] In the metal component of embodiment 1, the alpha titanium content in at least a portion of the first region may be 50% by volume or more and 100% by volume or less, or 60% by volume or more and 80% by volume or less. This high alpha titanium content in at least a portion of the surface of the metal component makes it easy to apply existing surface treatment methods to the metal component, and the reliability of the biocompatibility of the metal component is high. Examples of applications include implant components with a diameter of 3 mm or more. The implant component is suitable for use in, for example, intermediate teeth and molars.

[0050] In the present disclosure, the method for confirming that the alpha titanium content in at least a portion of the first region is 50% by volume or more and 100% by volume or less is as follows: The area percentage of alpha titanium is measured in multiple measurement regions using the same method as the method for confirming that the metal component includes a first region described above. In the present disclosure, if there are five or more measurement regions in which the area percentage of alpha titanium is 50% by volume or more and 100% by volume or less, it is confirmed that the alpha titanium content in at least a portion of the first region is 50% by volume or more and 100% by volume or less.

[0051] In the present disclosure, if the above confirmation method determines that the alpha titanium content in at least a portion of the first region of the metal component is 50% by volume or more and 100% by volume or less, the surface of the metal component is determined to include a region in which the alpha titanium content is 50% by volume or more and 100% by volume or less.

[0052] In at least a portion of the first region of the metal component of embodiment 1, the standard deviation of the alpha titanium content may be 1.5% or more, 1.5% to 4%, 1.6% to 3%, or 1.7% to 2%. This indicates that the alpha titanium content varies in the first region. This allows the surface of the same metal component to have both regions with a high alpha titanium content and regions with a low alpha titanium content, depending on the application.

[0053] In the present disclosure, the method for measuring the standard deviation of the alpha titanium content in at least a portion of the first region is as follows. The area percentage of alpha titanium is measured in multiple measurement regions using the same method as the above-mentioned method for confirming that the metal component contains a first region. The multiple measurement regions are arranged so that the depth-wise sides of adjacent measurement regions are in contact with each other. Of the multiple measurement regions, 10 measurement regions are identified that have an alpha titanium area percentage of 10 volume % or more and whose depth-wise sides are in contact with each other. The entire 10 measurement regions form a rectangle measuring 3 μm (depth length) × 80 μm (length perpendicular to the depth direction). The standard deviation of the alpha titanium content is calculated based on the alpha titanium content of each of the 10 measurement regions. In the present disclosure, this standard deviation corresponds to the standard deviation of the alpha titanium content in at least a portion of the first region.

[0054] In the surface of the metal component of embodiment 1, the first region may constitute the entire surface or may constitute a part of the surface. The area of ​​the first region on the surface of the metal component can be appropriately set depending on the application of the metal component. The percentage of the area of ​​the first region relative to the area of ​​the entire surface of the metal component may be, for example, 10% to 100%, 50% to 100%, or 60% to 80%.

[0055] ≪Second area≫ In the metal component of embodiment 1, the second region is a region that is 40 μm or more away from the surface of the metal component. Here, the region that is 40 μm or more away from the surface of the metal component can also be expressed as an internal region of the metal component that is 40 μm or more away from the surface of the metal component. The content of omega titanium having an omega phase crystal structure in the second region is 95% by volume or more, and may be 95% by volume or more to 100% by volume, 98% by volume or more to 100% by volume, 99% by volume or more to 100% by volume, or even 100% by volume.

[0056] In the present disclosure, the method for measuring the omega titanium content of the second region is as follows.

[0057] Step A2: A phase mapping image of the cross section of the metal member is obtained using the same method as steps A1 to C1 described above.

[0058] Step B2: In the phase mapping image, a rectangular measurement region of 3 μm × 8 μm is set within the region inside the imaginary line L2, which is 40 μm away from the surface 23 of the metal component 20 (the region below the imaginary line L2 in FIG. 1). If the surface of the metal component has irregularities, the line in the phase mapping image that passes through the position on the surface of the metal component that protrudes most toward the interior of the metal component and is perpendicular to the depth direction is regarded as the surface of the metal component. In the phase mapping image, the region inside the imaginary line L2, which is 40 μm away from the surface of the metal component, corresponds to the region of the metal component that is 40 μm or more away from the surface.

[0059] Step C2: Using the above software, measure the percentage of the area of ​​Omega Titanium relative to the total area of ​​the measurement region (hereinafter also referred to as "area percentage of Omega Titanium").

[0060] Step D2: The above-mentioned omega titanium area percentage is measured in five non-overlapping measurement areas. The average of the omega titanium area percentages of the five measurement areas is calculated. In the present disclosure, this average corresponds to the omega titanium content of the second area.

[0061] As long as measurements were taken on the same sample, it was confirmed that there was almost no variation in the measurement results, even if the cut-out location of the metal component and the measurement area were arbitrarily set and the omega titanium content of the second area was measured multiple times according to the above procedure.

[0062] In the metal member of embodiment 1, the second region can contain alpha titanium together with omega titanium. The total content of alpha titanium and omega titanium in the first region can be greater than 95 vol%, greater than 98 vol%, greater than 99 vol%, or even 100 vol%. The second region can also contain beta titanium as long as it does not impair the effects of the present disclosure.

[0063] In the present disclosure, the method for measuring the total content of alpha titanium and omega titanium in the second region is as follows: In each of the five measurement regions set in the method for measuring the omega titanium content in the second region, the software is used to measure the sum of the area percentage of alpha titanium and the area percentage of omega titanium relative to the total area of ​​the measurement region. The average of the sum of the area percentages of alpha titanium and omega titanium in the five measurement regions is calculated. In the present disclosure, this average corresponds to the total content of alpha titanium and omega titanium in the second region.

[0064] As long as measurements were taken on the same sample, it was confirmed that there was almost no variation in the measurement results, even if the cut-out location of the metal component and the measurement area were arbitrarily set and the total alpha titanium and omega titanium content of the second area was measured multiple times according to the above procedure.

[0065] In the metal component of embodiment 1, the average grain size of the crystal grains constituting the second region (hereinafter also referred to as "average grain size of the second region") may be 1 μm or more and 1000 μm or less. When the average grain size of the second region is 1 μm or more, the strength of the metal component is improved. When the average grain size of the second region is 1000 μm or less, the ductility of the metal component is improved.

[0066] The average grain size of the second region may be 3 μm or more and 500 μm or less, 5 μm or more and 200 μm or less, 10 μm or more and 100 μm or less, 10 μm or more and 50 μm or less, or 20 μm or more and 50 μm or less.

[0067] In the present disclosure, the average grain size of the second region is measured as follows: A cross section of a metal member is polished, and the polished surface is photographed using an optical microscope at a magnification of 100 times to obtain an optical microscope image.

[0068] A measurement field of 50 mm x 50 mm is set in the second region of the optical microscope image. The optical microscope image is processed using commercially available image analysis software, the circle-equivalent diameter of each crystal grain in the measurement field is measured, and the arithmetic mean of the circle-equivalent diameters is calculated.

[0069] The above measurement is performed on one measurement sample in three non-overlapping measurement fields, and the arithmetic mean of the circle-equivalent diameters in the three measurement fields is calculated. In the present disclosure, this mean corresponds to the average particle size of the second region.

[0070] It was confirmed that, as long as measurements were made on the same sample, there was almost no variation in the measurement results even when the average particle size of the second region was measured multiple times while changing the measurement field of view.

[0071] In the metal member of embodiment 1, the grain size of the crystal grains constituting the second region preferably has small variation in size from the viewpoint of homogenizing strength and ductility. In the volume-based cumulative grain size distribution of the crystal grains constituting the second region, the ratio D90 / D10 of the cumulative 90% grain size D90 from the small diameter side to the cumulative 10% grain size D10 from the small diameter side may be 5 or more and 1000 or less, or may be 10 or more and 1000 or less. A smaller value of D90 / D10 indicates smaller variation in grain size of the crystal grains.

[0072] The method for measuring the D90 / D10 is as follows. The circle-equivalent diameters of all crystal grains observed in the measurement field are measured using the same method as for measuring the average grain size of the second region. Based on this, a volume-based cumulative grain size distribution is created. Based on this cumulative grain size distribution, D90 / D10 is calculated.

[0073] It has been confirmed that, as long as measurements are made on the same sample, there is almost no variation in the measurement results even when the D90 / D10 measurement is performed multiple times at different measurement locations.

[0074] <Other areas> The metal component of embodiment 1 includes other regions in addition to the first and second regions. The other regions are, for example, regions sandwiched between the first and second regions, or regions within 3 μm of the surface of the metal component and having an alpha titanium content of less than 10% by volume. From a manufacturing standpoint, the omega titanium content of the other regions may be equal to or greater than the omega titanium content of the first region and equal to or less than the omega titanium content of the second region. This has been confirmed to ensure excellent strength and ductility of the metal component. The omega titanium content of the other regions may be, for example, 90% by volume or more, 93% by volume or more, 95% by volume or more, 98% by volume or more, 99% by volume or more, or even 100% by volume.

[0075] In the present disclosure, the method for measuring the omega titanium content in other regions is as follows.

[0076] Step A3: A phase mapping image of the cross section of the metal member is obtained using the same method as steps A1 to C1 described above.

[0077] Step B3: In the phase mapping image, a rectangular measurement region of 3 μm×8 μm is set in an area other than the first and second areas.

[0078] Step C3: Using the above software, measure the percentage of the area of ​​Omega Titanium relative to the total area of ​​the measurement region (hereinafter also referred to as "area percentage of Omega Titanium").

[0079] Step D3: The above-mentioned omega titanium area percentage is measured in five non-overlapping measurement areas. The average of the omega titanium area percentages of the five measurement areas is calculated. In the present disclosure, this average corresponds to the omega titanium content of the other areas.

[0080] As long as measurements were taken on the same sample, it was confirmed that there was almost no variation in the measurement results, even if the cut-out location and measurement area of ​​the metal component were arbitrarily set and the omega titanium content of other areas was measured multiple times according to the above procedure.

[0081] In the metal member of embodiment 1, the other regions may contain alpha titanium together with omega titanium. The total content of alpha titanium and omega titanium in the other regions may be greater than 95% by volume, greater than 98% by volume, greater than 99% by volume, or even 100% by volume. The other regions may also contain beta titanium as long as the effect of the present disclosure is not impaired.

[0082] In the present disclosure, the method for measuring the total content of alpha titanium and omega titanium in other regions is as follows: In each of the five measurement regions set in the above method for measuring the omega titanium content in other regions, the software is used to measure the sum of the area percentage of alpha titanium and the area percentage of omega titanium relative to the total area of ​​the measurement region. The average of the sum of the area percentages of alpha titanium and omega titanium in the five measurement regions is calculated. In the present disclosure, this average corresponds to the total content of alpha titanium and omega titanium in the other regions.

[0083] As long as measurements are taken on the same sample, it has been confirmed that there is almost no variation in the measurement results, even if the cut-out location and measurement area of ​​the metal component are arbitrarily set and the total alpha titanium and omega titanium content of other areas is measured multiple times according to the above procedure.

[0084] <Volume of metal parts> The volume of the metal member of embodiment 1 may be 0.001 cubic millimeters or more. This provides a sufficient size, making it easy to use for a variety of applications, such as implant members, members for fixing artificial skulls, members for fixing spinal devices, components for implantable devices, or components for sensor housings. Furthermore, since a sufficient amount of the second region can be ensured, the metal member can have superior strength and ductility.

[0085] The volume of the metal member may be 0.001 to 100,000 cubic millimeters, 10 to 100,000 cubic millimeters, or 100 to 100,000 cubic millimeters. The volume of the metal member is measured by Archimedes' method.

[0086] <Shape of metal parts> The shape of the metal member of embodiment 1 is not particularly limited and can be appropriately set depending on the application. The shape of the metal member may be, for example, a prism, a column, a cylinder, a rectangular tube, or a flat plate, or may be a screw shape, a nut shape, a bolt shape, or a washer shape. The shape of the metal member may also be a shape suitable for an implant member or a shape suitable for a biomedical metal member. Grooves or the like suitable for the application may be formed on the surface of the metal member. The thickness of the thinnest part of the metal member may be 0.2 mm or more.

[0087] <Tensile strength σB and elongation at break δ of metal components> The tensile strength σB of the metal member of embodiment 1 may be 400 MPa or more and less than 1550 MPa, 500 MPa or more and 1100 MPa or less, 900 MPa or more and 1100 MPa or less, or 950 MPa or more and 1000 MPa or less.

[0088] The fracture elongation δ of the metal member of the first embodiment may be 20% or more and 50% or less, 25% or more and 45% or less, or 30% or more and 45% or less.

[0089] In the present disclosure, the tensile strength σB and breaking elongation δ of a metal member are measured in accordance with JIS Z 2241:2011 "Method of tensile testing for metallic materials." The test temperature is 23°C ± 5°C.

[0090] <Vickers hardness> The Vickers hardness of the metal member of the second region of the first embodiment may be 130 Hv or more and 400 Hv or less, 200 Hv or more and 350 Hv or less, or 230 Hv or more and 280 Hv or less.

[0091] In the present disclosure, the Vickers hardness of a metal member is measured according to the following procedure: The metal material is cut to expose a cross section. A second region is identified in the cross section. The Vickers hardness of the second region is measured in accordance with JIS Z 2244:2009 "Vickers hardness test - Test method." The test temperature is 23°C ± 5°C.

[0092] <0.2% yield strength in tensile tests> The 0.2% proof stress in a tensile test of the metal member of embodiment 1 may be 250 MPa or more and 2000 MPa or less, 300 MPa or more and 1000 MPa or less, 600 MPa or more and 900 MPa or less, or 730 MPa or more and 870 MPa or less.

[0093] Measurement of 0.2% yield strength in tensile tests of metal components is carried out in accordance with JIS Z 2241:2011 "Method of tensile testing of metallic materials." The test temperature is 23°C ± 5°C.

[0094] <0.2% yield strength in compression test> The 0.2% yield strength in a compression test of the metal member of embodiment 1 may be 580 MPa or more and 5000 MPa or less, 900 MPa or more and 3000 MPa or less, 900 MPa or more and 2000 MPa or less, or 1100 MPa or more and 1500 MPa or less.

[0095] Measurement of 0.2% yield strength in compression tests of metal components is carried out in accordance with JIS R 1608:2003 "Test method for compressive strength of fine ceramics." The test temperature is 23°C ± 5°C.

[0096] <Metal component manufacturing method> The method for producing the metal component of the first embodiment can include a raw material preparation step, a high-pressure, high-temperature treatment step, and an electric discharge treatment step.

[0097] ≪Raw material preparation process≫ In the raw material preparation step, a conventional titanium alloy or pure titanium containing 98.8 mass% or more of titanium is prepared as the raw material. The titanium in the titanium alloy and pure titanium is alpha titanium having an alpha phase crystal structure.

[0098] <High-pressure, high-temperature processing> In the high-pressure, high-temperature treatment process, the raw material is placed in a sample container made of hexagonal boron nitride polycrystalline material, and then pressurized to 6-11 GPa using an ultra-high-pressure, high-temperature generator. After heating to 200-600°C, the material is held for 15-120 minutes to obtain a titanium material with an omega titanium content of 95% or more by volume. The resulting titanium material has a uniform structure, with an omega titanium content that is almost the same from the interior to the surface.

[0099] The ultra-high pressure, high temperature generator will be explained using Figure 2. Figure 2 is a schematic cross-sectional view of the high-pressure cell of the ultra-high pressure, high temperature generator. As shown in Figure 2, the high-pressure cell 10 comprises a pressure medium 1 having a regular octahedron shape, a sample container 2 placed inside the pressure medium 1, and a heating element 3 placed around the sample container 2. The sample container 2 is made of hexagonal boron nitride. The heating element 3 is made of graphite. A raw material 4 is sealed inside the sample container 2. The maximum load of the ultra-high pressure, high temperature generator is, for example, 2,800 tons.

[0100] <Discharge treatment process> In the discharge treatment step, a titanium material is subjected to discharge treatment to obtain a metal component. Specifically, in argon gas or pure water, a wire electrode or a flat electrode is brought close to the surface of the titanium material, and an electric current is passed through to generate a discharge, thereby discharging the surface of the titanium material. In the region of the titanium material that has been discharge-treated, a reverse phase transition from omega titanium to alpha titanium occurs, increasing the alpha titanium content. As a result, a first region with an alpha titanium content of 10% by volume or more is formed within a distance of 3 μm from the surface of the titanium material, and the metal component of embodiment 1 is obtained.

[0101] The conditions for the discharge treatment can be a discharge voltage of 0.05 to 5 kV, a discharge current of 0.01 to 500 A, and a pulse width of 1 to 1000 μs.

[0102] By adjusting the size of the area on the surface of the titanium material where the discharge treatment is performed, the percentage of the area of ​​the first area relative to the area of ​​the entire surface of the metal member can be adjusted.

[0103] <Embodiment 2: Implant member> An implant member according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 2") is an implant member made of the metal member of Embodiment 1. The implant member according to Embodiment 2 has a higher omega titanium content than implant members made of conventional titanium materials primarily composed of alpha titanium, and can have excellent strength and ductility. Furthermore, because the implant member according to Embodiment 2 contains alpha titanium on the surface, it is easy to treat the surface and is safe for the living body.

[0104] 3 is a schematic diagram showing the basic structure of an implant 30 using the implant member of embodiment 2. The implant 30 can include an implant body 31 to be embedded in a tooth root, an artificial tooth 34 fixed to the tip of the implant body, and an abutment 32 and an artificial tooth fixing screw 33 that connect the implant body 31 and the artificial tooth 34. The implant member of embodiment 2 may be the implant body, the abutment, or the artificial tooth fixing screw.

[0105] The implant in Fig. 3 is a two-piece type in which the implant body and the abutment are separate members. The implant member of embodiment 2 may be a one-piece type in which the implant body and the abutment are integrated.

[0106] In the implant member of embodiment 2, the first region of the metal member can constitute the surface of the implant member that comes into contact with the living body or that has the potential to come into contact with the living body, thereby further improving safety for the living body.

[0107] <Embodiment 3: Metallic material for biomedical use> A biomedical metal component according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 3") is made of the metal component of Embodiment 1. The biomedical metal component of Embodiment 3 has a higher omega titanium content than conventional biomedical metal components made of titanium materials primarily composed of alpha titanium, and can have excellent strength and ductility. Furthermore, because the biomedical metal component of Embodiment 3 contains alpha titanium on the surface, it is easy to treat the surface and is safe for the living body.

[0108] The biometallic component of embodiment 3 may be, for example, a component for fixing an artificial skull, a component for fixing a spinal device, a component for an implantable device, or a component for a sensor housing. The component for fixing an artificial skull or a component for fixing a spinal device may be a rod, a plate, or a screw.

[0109] In the biomedical metal component of embodiment 3, the first region of the metal component can constitute the surface of the biomedical metal component that comes into contact with a living body, or the surface that can come into contact with a living body.

[0110] <Appendix 1> A metal member containing 98.8% by mass or more of titanium, the surface of the metal member includes a first surface region; the first surface region is a region having an alpha titanium content of 10% by volume or more having an alpha phase crystal structure; the metal member includes a second region that is at a distance of 40 μm or more from a surface of the metal member, A metal member, wherein the content of omega titanium having an omega phase crystal structure in the second region is 95% by volume or more.

[0111] <Appendix 2> In the above Supplementary Note 1, the content of alpha titanium in at least a portion of the first surface region may be 10% by volume or more and less than 50% by volume.

[0112] <Appendix 3> In the above Supplementary Note 1, the content of alpha titanium in at least a portion of the first surface region may be 50% by volume or more and 100% by volume or less. [Example]

[0113] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0114] <Preparation of titanium materials> Alpha pure titanium having the composition shown in Table 1 was prepared as the raw material for each sample. The titanium in the alpha pure titanium is alpha titanium (referred to as "αTi" in Table 1).

[0115] Alpha pure titanium was placed in a sample container made of hexagonal boron nitride polycrystal, and pressurized to 8 GPa using a multi-anvil ultra-high pressure, high temperature apparatus (Voggenreiter "mavo press LPR 1000-400 / 50", graphite heating element, maximum load 2800 tons), then heated to 500°C and held for 15 minutes to obtain titanium materials, Samples 1 to 5. The obtained titanium materials were cylindrical, 10 mm high and 500 cubic millimeters in volume.

[0116] [Table 1]

[0117] <Measurement of titanium materials> For each sample of titanium material, the titanium material's composition, titanium crystal structure, tensile strength σB, fracture elongation δ, Vickers hardness, 0.2% yield strength in tensile tests, 0.2% yield strength in compression tests, average grain size of the crystal grains that make up the titanium material, and D90 / D10 of the crystal grains that make up the titanium material were measured. The measurement methods for each item are as follows. The results are shown in Tables 2 and 3.

[0118] <Titanium material composition> The titanium content of the titanium material, the content of other components other than titanium, and the types of other components were measured by ICP atomic emission spectroscopy.

[0119] <Titanium crystal structure> The cross section of the titanium material obtained for each sample was cut along the normal line to expose the cross section. The cross section was mirror-polished using a cross-section polisher (manufactured by JEOL Ltd.). The mirror-polished surface was analyzed using SEM-EBSD to identify the titanium crystal structure. The measurement conditions for SEM-EBSD were an acceleration voltage of 15 kV, a current value of 15 nA, a magnification of 1000 to 10000 times, and a step size of 0.1 to 0.02 μm. In all samples, the titanium crystal structure was confirmed to be 100% omega titanium by volume, from the surface to the interior of the titanium material.

[0120] <Tensile strength σB, elongation at break δ> The tensile strength σB and fracture elongation δ of titanium materials were measured in accordance with JIS Z 2241:2011 "Method of tensile testing for metallic materials." The test temperature was 23°C.

[0121] <Vickers hardness> The Vickers hardness of the titanium material was measured in accordance with JIS Z 2244:2009 "Vickers hardness test - Test method." The test temperature was 23°C.

[0122] <0.2% yield strength in tensile tests> Measurement of the 0.2% yield strength in the tensile test of titanium materials was carried out in accordance with JIS Z 2241:2011 "Method of tensile test for metallic materials." The test temperature was 23°C.

[0123] <0.2% yield strength in compression test> Measurement of the 0.2% yield strength in a compression test of titanium materials was carried out in accordance with JIS R 1608:2003 "Test method for compressive strength of fine ceramics." The test temperature was 23°C.

[0124] <Average grain size of the crystal grains that make up titanium material, D90 / D10> The average grain size and D90 / D10 of the crystal grains constituting the titanium material were measured by the method described in the first embodiment.

[0125] [Table 2]

[0126] [Table 3]

[0127] <Production of metal components> Multiple samples of titanium material, Samples 1 to 5, were prepared. The entire surface of each titanium material was subjected to electrical discharge treatment to obtain the metal component of each sample. The electrical discharge treatment was carried out in argon gas by passing an electric current through a wire electrode wire close to the surface of the titanium material to generate an electrical discharge, thereby treating the entire surface of the titanium material. The electrical discharge treatment conditions for each sample are shown in Table 4.

[0128] [Table 4]

[0129] <Metal component measurement> For each sample of metal component, the titanium content, the content of components other than titanium, the type of components other than titanium, the titanium crystal structure, the presence or absence of a first region, the alpha titanium content of the first region, the standard deviation of the alpha titanium content in the first region, and the omega titanium content of the second region were measured. Specific measurement methods were as described in embodiment 1. The results are shown in Table 5. The presence of a first region was confirmed in all samples.

[0130] [Table 5]

[0131] The metal members of Samples 101 to 105, Samples 201 to 205, and Samples 301 to 305 correspond to Examples.

[0132] For each sample, the tensile strength σB, fracture elongation δ, 0.2% yield strength in the tensile test, 0.2% yield strength in the compression test, and Vickers hardness in the second region were measured, and it was confirmed that the values ​​for all samples were almost equivalent to those of the titanium material before discharge treatment.

[0133] The average grain size and D90 / D10 of the crystal grains constituting the second region of each sample were measured, and it was confirmed that the values ​​for all samples were almost the same as those of the titanium material before the discharge treatment.

[0134] Although the embodiments and examples of the present disclosure have been described above, it is originally intended that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways. The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the embodiments and examples described above, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims. [Explanation of symbols]

[0135] 1 pressure medium, 2 sample container, 3 heating element, 4 raw material, 10 high-pressure cell, 20 metal member, 21 first region, 22 second region, 23 surface, 24 other region.

Claims

1. A metal member containing 98.8% by mass or more of titanium, the metal member includes a first region and a second region, the first region is a region within 3 μm from the surface of the metal member and having an alpha titanium content of 10% by volume or more having an alpha phase crystal structure, the second region is a region that is 40 μm or more away from the surface of the metal member, A metal member, wherein the content of omega titanium having an omega phase crystal structure in the second region is 95% by volume or more.

2. The metal component according to claim 1 , wherein the content of the alpha titanium in at least a portion of the first region is equal to or greater than 10% by volume and less than 50% by volume.

3. The metal component according to claim 1 , wherein the content of the alpha titanium in at least a portion of the first region is 50% by volume or more and 100% by volume or less.

4. The metal component according to claim 1 , wherein the standard deviation of the alpha titanium content in at least a portion of the first region is 1.5% or more.

5. An implant member comprising the metal member according to any one of claims 1 to 4.

6. A biomedical metal component comprising the metal component according to any one of claims 1 to 4.

7. 7. The biomedical metal component according to claim 6, which is a component for fixing an artificial skull, a component for fixing a spinal device, a component for an implantable device, or a component for a sensor housing.

8. The biomedical metal member according to claim 7, wherein the artificial skull fixing member or the spinal device fixing member is a rod, a plate, or a screw.

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