Metal components, implant components, and biocompatible metal components

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] This disclosure relates to metal members, implant members, and metallic biomaterials.

Background Art

[0002] Titanium materials have been used in fields such as the aerospace industry and the automotive industry because of their high specific strength. Also, due to their excellent biocompatibility, the demand for metallic biomaterials such as dental implants is increasing.

[0003] The titanium that constitutes currently widely used titanium materials is alpha titanium having a crystal structure of the alpha phase. Alpha pure titanium with a high alpha titanium content has high elongation (hereinafter also referred to as ductility), but has a small tensile strength (hereinafter also referred to as strength). On the other hand, titanium alloys obtained by adding other metals to titanium have high tensile strength but small elongation. Thus, in conventional titanium materials mainly composed of alpha titanium, strength and ductility are in a trade-off relationship, and it has been impossible to obtain a titanium material that can achieve both high strength and high ductility.

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

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] The metal member of this disclosure is a metal member containing 98.8 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 of the surface of the metal member, and in which the content of alpha titanium having an alpha phase crystal structure is 10 volume% or more. The second region is a region where the distance from the surface of the metal member is 40 μm or more. The metal component has a content of 95% by volume or more of omega titanium having the omega phase crystal structure of the second region. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic cross-sectional view of the metal member of Embodiment 1. [Figure 2] Figure 2 is a schematic cross-sectional view of the high-pressure cell of the ultra-high-pressure, high-temperature generating device used in the manufacture of the metal component of Embodiment 1. [Figure 3] Figure 3 is a schematic diagram showing the basic structure of an implant using the implant member of Embodiment 2. [Modes for carrying out the invention]

[0008] Issues that this disclosure aims to resolve According to Patent Document 1, the higher the content of omega titanium, which has an omega phase crystal structure in titanium material, the better the strength and ductility. Therefore, from the viewpoint of improving strength and ductility, it is presumed that increasing the content of omega titanium in titanium material is effective.

[0009] On the other hand, alpha-titanium has a longer track record of use than omega-titanium, and there is abundant information available regarding surface treatment methods and biocompatibility. From the perspective of ease of surface treatment and safety when used as a biomaterial, the presence of alpha-titanium on the surface of titanium material is required.

[0010] Therefore, the present disclosure aims to provide a metal component, implant component, and biomedical component that has a higher omega titanium content than conventional titanium materials mainly composed of alpha titanium, and that also contains alpha titanium on its surface.

[0011] Effects of this Disclosure According to this disclosure, it is possible to provide metal components, implant components, and biomedical components that have a higher omega titanium content than conventional titanium materials mainly composed of alpha titanium, and that also contain alpha titanium on their surface.

[0012] Description of the embodiments of this disclosure First, the embodiments of this disclosure will be listed and described. (1) The metal members of this disclosure are A metal component 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 of the surface of the metal member, and in which the content of alpha titanium having an alpha phase crystal structure is 10 volume% or more. The second region is a region where the distance from the surface of the metal member is 40 μm or more. The metal component has a content of 95% by volume or more of omega titanium having the omega phase crystal structure of the second region.

[0013] According to this disclosure, it is possible to provide a metal component that has a higher omega titanium content than conventional titanium materials mainly composed of alpha titanium, and that also contains alpha titanium on its surface.

[0014] (2) In (1) above, 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. According to this, at least a portion of the surface of the metal member can have particularly excellent strength, and the metal member can be suitably used in applications where particularly high strength is required.

[0015] (3) In the above (1), in at least a part of the first region, the content of the alpha titanium may be 50% by volume or more and 100% by volume or less. According to this, in at least a part of the surface of the metal member, since the content of alpha titanium is high, it is easy to apply an existing surface treatment method to the metal member, and the reliability regarding the biocompatibility of the metal member is high.

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

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

[0018] According to this, the implant member has a higher content of omega titanium than an implant member made of a conventional titanium material mainly composed of alpha titanium, and can have excellent strength and ductility. In addition, since the implant member contains alpha titanium on the surface, it is excellent in the ease of surface treatment and the safety to the living body.

[0019] (6) The metal member for living body of the present disclosure is a metal member for living body made of the metal member according to any one of the above (1) to (4).

[0020] According to this, the metal member for living body has a higher content of omega titanium than a metal member for living body made of a conventional titanium material mainly composed of alpha titanium, and can have excellent strength and ductility. In addition, since the metal member for living body contains alpha titanium on the surface, it is excellent in the ease of surface treatment and the safety to the living body.

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

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

[0023] Details of the Disclosed Embodiment Specific examples of the metal components, implant components, and biomedical metal components of this disclosure will be described below with reference to the drawings. In the drawings of this disclosure, the same reference numerals indicate the same or equivalent parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been modified as appropriate for clarity and simplification of the drawings and do not necessarily represent actual dimensional relationships.

[0024] In this disclosure, the notation "A~B" means an upper and lower limit of the range (i.e., A or greater and B or less), and if there is no unit specified for A, but a unit is specified only for B, then the unit for A and the unit for B are the same.

[0025] <Embodiment 1: Metal Member> A metal member relating to one embodiment of this disclosure (hereinafter also referred to as "Embodiment 1") is A metal component 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 of the surface of the metal member, and in which the content of alpha titanium having an alpha phase crystal structure is 10 volume% or more. The second region is a region where the distance from the surface of the metal member is 40 μm or more. The metal component has a content of 95% by volume or more of omega titanium having a crystal structure of the omega phase in the second region.

[0026] <Titanium content> The metal member of Embodiment 1 contains 98.8% by mass or more of titanium. As a result, the metal member has high specific strength and excellent biocompatibility. The titanium content of the metal member may be 98.8% by mass or more and 100% by mass or less, 98.9% by mass or more and 100% by mass or less, 99.0% by mass or more and 99.99% by mass or less, 99.2% by mass or more and 99.99% by mass or less, 99.3% by mass or more and 99.99% by mass or less, or 99.4% by mass or more and 99.99% by mass or less.

[0027] The metal component of Embodiment 1 may consist of titanium and other components other than titanium. The other components may consist of 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), gold (Au), etc.) and unavoidable 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) emission spectroscopy if the other components are transition metal elements. If the other components are elements other than transition metal elements, such as hydrogen, carbon, nitrogen, and oxygen, the content is measured by secondary ion mass spectrometry (SIMS).

[0029] The titanium content of a metal component is determined by measuring the content of components other than titanium using the method described above, setting the total mass of the metal component to 100%, and then subtracting the content of components other than titanium.

[0030] <Structure of metal components> Figure 1 is a schematic cross-sectional view of the metal member of Embodiment 1. As shown in Figure 1, the metal member of Embodiment 1 includes a first region and a second region.

[0031] ≪First area≫ In the metal member of Embodiment 1, the first region is a region within 3 μm of the surface of the metal member and having an alpha-phase crystalline structure with a content of 10 volume% or more of alpha titanium. Here, the region within 3 μm of the surface of the metal member can also be expressed as the region sandwiched between the surface of the metal member and a virtual plane at a distance of 3 μm from the surface of the metal member to the interior of the metal member. In Figure 1, the entire surface of the metal member is composed of the first region, but the first region may constitute only a part of the surface of the metal member.

[0032] In the metal member of Embodiment 1, the alpha titanium content in the first region is 10 volume% or more, may be 10 volume% to 100 volume%, 20 volume% to 100 volume%, 40 volume% to 100 volume%, 60 volume% to 100 volume%, 80 volume% to 100 volume%, or 100 volume%.

[0033] In this disclosure, the method for confirming that the metal member includes the first region is as follows:

[0034] Procedure A1. The surface of the metal component is observed using a micro-X-ray diffractometer (Rigaku Corporation's "SmartLab" trademark) to identify the region where alpha-titanium is present. The measurement conditions are as follows: X-ray used: Cu-Ka, excitation conditions: 45kV, 200mA, incident slit size: 0.8mm × vertical 0.1mm, detector: HyPix-3000 (2D), scanning method: 2θ-θ scan, measurement range: 2θ = 25°-90°, step size: 0.03°, scan speed: 0.5° / min. The region where diffraction peaks are observed in the range of 2θ = 39.7°-40.4° is determined to be the region where alpha-titanium is present.

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

[0036] Procedure B1. Observe the mirror-finished cross-section of the metal component using an electron backscatter diffractometer (SEM-EBSD; SEM: Carl Zeiss "Gemini 450" (trademark), EBSD: Oxford "Symmetry" (trademark)) attached to a scanning electron microscope. The observation magnification should be 1000 to 10000x. The measurement conditions should be an acceleration voltage of 15kV, a current of 15nA, and 0.1 to 0.02μm / step. Perform EBSD analysis on the obtained observation image.

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

[0038] Procedure D1. In the phase mapping image, a rectangular measurement area of ​​3 μm × 8 μm is set within the region sandwiched between the surface 23 of the metal member and a virtual line L1, which is 3 μm away from the surface 23 to the interior of the metal member 20. The measurement area has a length of 3 μm in the depth direction and a length of 8 μm in the direction perpendicular to the depth direction. If the surface of the metal member is uneven, in the phase mapping image, the line that passes through the position of the metal member's surface that protrudes furthest inward and is perpendicular to the depth direction is considered to be the surface of the metal member. In this disclosure, the depth direction is the direction perpendicular to the average line of the metal member's surface as defined in JIS B 0601-1994 in the phase mapping image. The region sandwiched between the surface of the metal member and the virtual line L1 in the phase mapping image corresponds to the region of the metal member within 3 μm of the surface of the metal member.

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

[0040] Procedure F1. The area percentage of alpha titanium described above is measured in multiple non-overlapping measurement regions. The multiple measurement regions may be located on the same cross-section of the metal member, or they may be located on different cross-sections. In this disclosure, if there are five or more measurement regions in which the area percentage of alpha titanium is 10 volume% or more, it is confirmed that the metal member includes a first region within 3 μm of the surface of the metal member, and in which the content of alpha titanium having an alpha phase crystal structure is 10 volume% or more.

[0041] In this disclosure, as described in procedure F1 above, even if there are five or more measurement areas on the same cross-section of the metal member (hereinafter also referred to as the "first cross-section") in which the area percentage of alpha titanium is 10 volume% or more, the metal member is determined to include the first cross-section. In this case, it can be confirmed that the first cross-section also exists in a direction perpendicular to the first cross-section by the following procedure: The metal member including the first cross-section is cut along the normal to the first cross-section so as to pass through the first cross-section, exposing the second cross-section. In the second cross-section, the alpha titanium content in the measurement areas is measured in the same manner as in procedures A1 to F1 above. If the second cross-section includes five or more measurement areas in which the alpha titanium content is 10 volume% or more, it is confirmed that the first cross-section also exists in a direction perpendicular to the first cross-section.

[0042] Furthermore, in the same metal component, in the region where alpha-titanium is present and the results observed with a micro-X-ray diffractometer in procedure A1 are almost identical, it has been confirmed that the alpha-titanium content of the first region is almost identical in multiple different cross-sections obtained by cutting along the normal to the region. This indicates that the first region extends in the in-plane direction on the surface of the metal component.

[0043] In this disclosure, if the above verification method confirms that the metal member includes the first region, it is determined that the surface of the metal member includes a region in which the alpha-titanium content is 10 volume percent or more.

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

[0045] In this disclosure, the method for measuring the total content of alpha titanium and omega titanium in the first region is as follows: Ten measurement regions are identified in which the area percentage of alpha titanium is 10 volume% or more, based on the method for confirming that the above metal component includes the first region. In each measurement region, the sum of the percentage of alpha titanium area and the percentage of omega titanium area relative to the total area of ​​the measurement region is measured using the above software. The average of the sum of the percentages of alpha titanium area and omega titanium area for the ten measurement regions is calculated. In this disclosure, this average corresponds to the total content of alpha titanium and omega titanium in the first region.

[0046] In the metal member of Embodiment 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, or 20% by volume or more and 40% by volume. As a result, since at least a portion of the surface of the metal member has an alpha-titanium content of less than 50% by volume, it is easy to ensure excellent strength, and it can be suitably used in applications where strength is particularly required. Examples of applications include implant members with a diameter of 2 mm or more and 4 mm or less. Such implant members are preferably used, for example, in anterior teeth.

[0047] In this 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 the first region. In this 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 this disclosure, if the above verification method confirms that the alpha-titanium content in at least a portion of the first region of the metal member is 10 volume% or more and less than 50 volume%, then the surface of the metal member is determined to include a region in which the alpha-titanium content is 10 volume% or more and less than 50 volume%.

[0049] In the metal member 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 60% by volume or more and 80% by volume. This allows for a high alpha-titanium content in at least a portion of the surface of the metal member, making it easier to apply existing surface treatment methods to the metal member and providing high reliability regarding the biocompatibility of the metal member. Examples of applications include implant members with a diameter of 3 mm or more. Such implant members are preferably used for intermediate teeth and molars, for example.

[0050] In this 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 the first region. In this 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 this disclosure, if the above-described verification method determines that the alpha-titanium content in at least a portion of the first region of the metal member is 50% by volume or more and 100% by volume or less, then the surface of the metal member 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 member 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 there is variation in the alpha-titanium content in the first region. This allows for the coexistence of regions with high alpha-titanium content and regions with low alpha-titanium content on the surface of the same metal member, depending on the application.

[0053] In this 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 method for confirming that the metal member includes the first region. The multiple measurement regions are arranged so that the depth-direction edges of adjacent measurement regions are touching. From the multiple measurement regions, 10 measurement regions are identified in which the area percentage of alpha-titanium is 10 volume% or more and the depth-direction edges of adjacent measurement regions are touching. The 10 measurement regions as a whole form a rectangle of 3 μm (length in the depth direction) × 80 μm (length in the direction perpendicular to the depth direction). Based on the alpha-titanium content of each of the 10 measurement regions, the standard deviation of the alpha-titanium content is calculated. In this 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 first embodiment, the first region may constitute the entire surface or a part of the surface. The area of ​​the first region on the surface of the metal member can be appropriately set depending on the application of the metal member. The percentage of the area of ​​the first region to the total surface area of ​​the metal member may be, for example, 10% or more and 100%, 50% or more and 100%, or 60% or more and 80%.

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

[0056] In this disclosure, the method for measuring the omega titanium content in the second region is as follows:

[0057] Procedure A2. Obtain a phase mapping image of the cross-section of the metal member using the same method as in Procedures A1 to C1 above.

[0058] Procedure B2. In the phase mapping image, a rectangular measurement area of ​​3 μm × 8 μm is set within the region inside the virtual line L2, which is 40 μm from the surface 23 of the metal member 20 (the region below the virtual line L2 in Figure 1). If the surface of the metal member is uneven, in the phase mapping image, the line that passes through the position of the metal member's surface that protrudes furthest inward and is perpendicular to the depth direction is considered to be the surface of the metal member. The region inside the virtual line L2, which is 40 μm from the surface of the metal member in the phase mapping image, corresponds to the region of the metal member that is 40 μm or more from the surface.

[0059] Procedure C2. Using the software described above, 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] Procedure D2. The area percentage of omega titanium described above is measured in five non-overlapping measurement areas. The average of the area percentages of omega titanium in the five measurement areas is calculated. In this disclosure, this average corresponds to the omega titanium content of the second area.

[0061] As long as measurements are performed on the same sample, it was confirmed that there is almost no variation in the measurement results even when the cutting location of the metal component and the measurement area are arbitrarily set and the omega titanium content of the second region is measured multiple times according to the procedure described above.

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

[0063] In this 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 out in the above method for measuring the content of omega titanium in the second region, the sum of the percentage of the area of ​​alpha titanium and the percentage of the area of ​​omega titanium relative to the total area of ​​the measurement region is measured using the above software. The average of the sum of the percentages of the area of ​​alpha titanium and the percentage of the area of ​​omega titanium in the five measurement regions is calculated. In this disclosure, this average corresponds to the total content of alpha titanium and omega titanium in the second region.

[0064] As long as measurements are performed on the same sample, it was confirmed that there is almost no variation in the measurement results even when the cutting location of the metal component and the measurement area are arbitrarily set and the total content of alpha titanium and omega titanium in the second region is measured multiple times according to the procedure described above.

[0065] In the metal member 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 between 1 μm and 1000 μm. If the average grain size of the second region is 1 μm or more, the strength of the metal member is improved. If the average grain size of the second region is 1000 μm or less, the ductility of the metal member is improved.

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

[0067] In this disclosure, the method for measuring the average particle size of the second region is as follows: The cross-section of the metal member is polished, and the polished surface is imaged at a magnification of 100x using an optical microscope to obtain an optical microscope image.

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

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

[0070] Furthermore, it was confirmed that, as long as measurements were performed on the same sample, there was almost no variation in the measurement results even when the average particle size in the second region was measured multiple times with a different measurement field.

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

[0072] The measurement method for D90 / D10 is as follows: Using the same method as the measurement method for the average grain size of the second region described above, the equivalent circular diameter of all crystal grains observed within the measurement field is measured, and a volume-based cumulative grain size distribution is created based on this. D90 / D10 is calculated based on this cumulative grain size distribution.

[0073] Furthermore, it was confirmed that, as long as the measurements were performed on the same sample, there was almost no variation in the measurement results even when the D90 / D10 measurements were performed multiple times with different measurement locations.

[0074] <Other areas> The metal member of Embodiment 1 includes areas other than the first and second regions. These other regions include, for example, the region sandwiched between the first and second regions, and the region where the distance from the surface of the metal member to the interior of the metal member is within 3 μm and the alpha titanium content is less than 10 volume%. From a manufacturing standpoint, the omega titanium content of the other regions may be greater than or equal to the omega titanium content of the first region and less than or equal to the omega titanium content of the second region. It has been confirmed that this ensures excellent strength and ductility of the metal member. The omega titanium content of the other regions may be, for example, 90 volume% or more, 93 volume% or more, 95 volume% or more, 98 volume% or more, 99 volume% or more, or 100 volume%.

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

[0076] Procedure A3. Obtain a phase mapping image of the cross-section of the metal member using the same method as in Procedures A1 to C1 above.

[0077] Procedure B3. In the phase mapping image, set a rectangular measurement area of ​​3 μm × 8 μm within the areas other than the first and second regions.

[0078] Procedure C3. Using the software described above, 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] Procedure D3. The area percentage of omega titanium described above is measured in five non-overlapping measurement areas. The average of the area percentages of omega titanium in the five measurement areas is calculated. In this disclosure, this average corresponds to the omega titanium content in the other areas.

[0080] As long as measurements are performed on the same sample, it was confirmed that there is almost no variation in the measurement results even when the cutting location of the metal component and the measurement area are arbitrarily set and the omega titanium content of other areas is measured multiple times according to the procedure described above.

[0081] In the metal member of Embodiment 1, the other regions may contain alpha titanium along with omega titanium. The total content of alpha titanium and omega titanium in the other regions may be greater than 95 vol%, 98 vol% or more, 99 vol% or more, or 100 vol%. The other regions may also contain beta titanium, as long as it does not impair the effects of the present disclosure.

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

[0083] As long as measurements are performed on the same sample, it was confirmed that there is almost no variation in the measurement results even when the cutting location of the metal component and the measurement area are arbitrarily set and the total content of alpha titanium and omega titanium in other areas is measured multiple times according to the procedure described above.

[0084] <Volume of metal component> The volume of the metal member in Embodiment 1 may be 0.001 cubic millimeters or more. This allows for sufficient size, making it easy to use in various applications such as implant members, artificial skull fixation members, spinal device fixation members, components of implantable devices, or components of sensor housings. Furthermore, because sufficient volume can be secured in the second region, the metal member can have superior strength and ductility.

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

[0086] <Shape of metal component> The shape of the metal member in Embodiment 1 is not particularly limited and can be set as appropriate depending on the application. The shape of the metal member may be, for example, a rectangular prism, cylinder, tube, rectangular tube, or flat plate, or it may be a screw shape, nut shape, bolt shape, or washer shape. Furthermore, the shape of the metal member may 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 in 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 in Embodiment 1 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 this disclosure, the tensile strength σB and fracture elongation δ of the metal members are measured in accordance with JIS Z 2241:2011 "Tensile Test Method for Metallic Materials". The test temperature is 23°C ± 5°C.

[0090] <Vickers hardness> The Vickers hardness of the metal member in the second region of Embodiment 1 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 this disclosure, the Vickers hardness of a metal component is measured using the following procedure: The metal material is cut to expose the cross-section. A second region is identified in the cross-section. The Vickers hardness is measured in the second region in accordance with JIS Z 2244:2009 "Vickers hardness test - Test method". The test temperature is 23°C ± 5°C.

[0092] <0.2% proof stress in tensile tests> The 0.2% yield strength in the tensile test of the metal member in 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] The 0.2% proof stress in tensile tests of metal components shall be measured in accordance with JIS Z 2241:2011 "Tensile Testing Method for Metallic Materials". The test temperature shall be 23°C ± 5°C.

[0094] <0.2% proof stress in compression tests> The 0.2% proof stress in the compression test of the metal member in 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] The 0.2% proof stress in compression tests of metal components shall be measured in accordance with JIS R 1608:2003 "Test Method for Compressive Strength of Fine Ceramics". The test temperature shall be 23°C ± 5°C.

[0096] <Method for manufacturing metal components> The manufacturing method for the metal member of Embodiment 1 may include a raw material preparation step, a high-pressure high-temperature treatment step, and a discharge treatment step.

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

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

[0099] The ultra-high pressure and 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 and high temperature generator. As shown in Figure 2, the high-pressure cell 10 comprises a pressure medium 1 having the shape of a regular octahedron, 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. The raw material 4 is sealed inside the sample container 2. The maximum load of the ultra-high pressure and high temperature generator is, for example, 2800 tons.

[0100] ≪Discharge Treatment Process≫ In the discharge treatment process, 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 planar electrode is brought close to the surface of the titanium material, and an electric current is passed to generate a discharge, thereby discharging the surface of the titanium material. In the region of the titanium material where the discharge treatment has been performed, a reverse phase transition from omega titanium to alpha titanium occurs, and the alpha titanium content increases. As a result, a first region is formed in the area within 3 μm of the surface of the titanium material, in which the alpha titanium content is 10 volume% or more, and the metal component of Embodiment 1 is obtained.

[0101] The discharge treatment conditions 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 where the discharge treatment is performed on the surface of the titanium material, the percentage of the area of ​​the first region relative to the total surface area of ​​the metal component can be adjusted.

[0103] <Embodiment 2: Implant Member> An implant member in 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 of Embodiment 2 has a higher omega titanium content than conventional implant members made of titanium material mainly composed of alpha titanium, and can have superior strength and ductility. Furthermore, because the implant member of Embodiment 2 contains alpha titanium on its surface, it is easy to surface treat and has superior biocompatibility.

[0104] Figure 3 is a schematic diagram showing the basic structure of an implant 30 using the implant member of Embodiment 2. The implant 30 may comprise an implant body 31 embedded in the 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 connecting 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 Figure 3 is a two-piece type in which the implant body and the abutment are separate components. The implant component in Embodiment 2 may be a one-piece type implant component 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 a surface that has the potential to come into contact with the living body. This further improves safety for the living body.

[0107] <Embodiment 3: Biomedical Metal Components> The biocompatible metal member of one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 3") consists of the metal member of Embodiment 1. The biocompatible metal member of Embodiment 3 has a higher omega titanium content than conventional biocompatible metal members made of titanium material mainly composed of alpha titanium, and can have excellent strength and ductility. Furthermore, because the biocompatible metal member of Embodiment 3 contains alpha titanium on its surface, it is easy to surface treat and has excellent safety for living organisms.

[0108] The biocompatible metal 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 the housing of a sensor. The artificial skull fixing component or the spinal device fixing component may be a rod, a plate, or a screw.

[0109] In the biocompatible metal member of Embodiment 3, the first region of the metal member can constitute a surface of the biocompatible metal member that comes into contact with a living organism, or a surface that has the potential to come into contact with a living organism.

[0110] <Note 1> A metal component 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 in which the content of alpha titanium having an alpha phase crystal structure is 10 volume% or more. The metal member includes a second region that is 40 μm or more away from the surface of the metal member. A metal component having a crystal structure of the omega phase in the second region, with a content of 95 volume% or more of omega titanium.

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

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

[0113] This embodiment will be described in more detail by reference to examples. However, this embodiment is not limited by these examples.

[0114] <Fabrication of titanium materials> As the raw material for each sample, alpha-pure titanium having the composition listed in Table 1 was prepared. The titanium in alpha-pure titanium is alpha-titanium (indicated as "αTi" in Table 1).

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

[0116] [Table 1]

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

[0118] <Composition of Titanium Material> The titanium content, the content of other components besides titanium, and the types of other components were measured using ICP emission spectrometry in the titanium material.

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

[0120] <Tensile strength σB, elongation at break δ> The tensile strength σB and elongation at break δ of the titanium material were measured in accordance with JIS Z 2241:2011 "Tensile Testing Methods for Metallic Materials". The test temperature was 23°C.

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

[0122] <0.2% proof stress in tensile tests> The 0.2% yield strength measurement in the tensile test of titanium materials was performed in accordance with JIS Z 2241:2011 "Tensile Testing Method for Metallic Materials". The test temperature was 23°C.

[0123] <0.2% proof stress in compression tests> The 0.2% yield strength measurement in the compression test of titanium material was performed 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 crystal grains constituting 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 Embodiment 1.

[0125] [Table 2]

[0126] [Table 3]

[0127] <Fabrication of metal components> Multiple samples of titanium material were prepared for each of the five samples (Sample 1 to Sample 5). Each titanium material was subjected to a complete electrical discharge treatment to obtain the metal components of each sample. In the electrical discharge treatment, an electric current was passed through the surface of the titanium material in an argon gas atmosphere, with a wire electrode close to the surface, generating a discharge and treating the entire surface of the titanium material. The conditions for the electrical discharge treatment of each sample are shown in Table 4.

[0128] [Table 4]

[0129] <Measurement of metal components> For each metal component of the sample, the titanium content, the content of non-titanium components, the types of non-titanium components, the titanium crystal structure, the presence or absence of the 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. The specific measurement method is as described in Embodiment 1. The results are shown in Table 5. It was confirmed that the first region was present in all samples.

[0130] [Table 5]

[0131] The metal components of Samples 101 to 105, Samples 201 to 205, and Samples 301 to 305 correspond to the examples.

[0132] For each sample, the tensile strength σB, elongation at break 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 all samples were approximately equivalent to the values ​​of the titanium material before electrical discharge treatment.

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

[0134] As described above, the embodiments and examples of this disclosure have been explained, but it is also intended from the outset that the configurations of each of the embodiments and examples described above may be combined or modified in various ways as appropriate. The embodiments and examples disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the embodiments and examples described above, and all modifications within the scope of the claims are intended to be included in the meaning of equivalents and within the scope. [Explanation of symbols]

[0135] 1 Pressure medium, 2 Sample container, 3 Heating element, 4 Raw material, 10 High-pressure cell, 20 Metal component, 21 First region, 22 Second region, 23 Surface, 24 Other regions.

Claims

1. A metal component 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 of the surface of the metal member, and in which the content of alpha titanium having an alpha phase crystal structure is 10 volume percent or more. The second region is a region where the distance from the surface of the metal member is 40 μm or more. A metal component having a crystal structure of the omega phase in the second region, with a content of 95% by volume or more of omega titanium.

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

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

4. The metal member according to any one of claims 1 to 3, wherein in at least a portion of the first region, the standard deviation of the alpha titanium content is 1.5% or more.

5. An implant member comprising a metal member according to any one of claims 1 to 3.

6. A biocompatible metal member comprising the metal member described in any one of claims 1 to 3.

7. The bio-metal member according to claim 6, wherein the bio-metal member is a member for fixing an artificial skull, a member for fixing a spinal device, a component of an implantable device, or a component of a sensor housing.

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

Images