High-strength ti-nb-zr alloy with uniform hardness and low elastic modulus, and method for manufacturing same

Abstract

A high-strength Ti-Nb-Zr alloy with a uniform hardness and a low elastic modulus, and a method for manufacturing same are disclosed. The method for manufacturing a Ti-Nb-Zr alloy having an alloy composition comprising 12.5-14 wt% of Nb, 12.5-14 wt% of Zr and the balance of Ti and inevitable impurities, according to the present invention, comprises the steps of: (a) preparing a Ti-Nb-Zr alloy base material having the alloy composition; (b) cold-working the Ti-Nb-Zr alloy base material at a temperature of 450 °C or lower; and (c) heat-treating same at a temperature of 450 °C or lower.

Description

High-strength TI-NB-ZR alloy having uniform hardness and low elastic modulus and method for manufacturing the same

[0001] The present invention relates to the field of metallic materials, and more specifically to a high-strength Ti-Nb-Zr alloy having uniform hardness and a low elastic modulus suitable for biomedical devices such as dental implants.

[0002] In addition, the present invention relates to a method for manufacturing a high-strength Ti-Nb-Zr alloy having uniform hardness and a low elastic modulus.

[0003] Much research is being conducted on Ti or Ti alloys as materials for dental implants.

[0004] In general, if a dental implant fractures during use, it causes severe pain and the burden of re-surgery for the patient. Most fractures are vertical fractures occurring perpendicular to the length of the implant, and increasing the strength of the material is essential to prevent this.

[0005] Grade 4 pure Ti, which is currently widely used as a material for dental implants, has low strength and is therefore used in a work-hardened state through cold working. However, excessive work hardening drastically reduces elongation.

[0006] Meanwhile, dental implant materials must maintain an elongation of at least 10% according to ASTM F67 standards. To satisfy this, there are limits to work hardening, and as a result, it is typically difficult for the tensile strength to exceed 950 MPa.

[0007] Meanwhile, non-uniformity in hardness along the diametrical direction of the implant may occur during the cold working process. This non-uniformity in diametrical hardness is a major cause of parallel fracture.

[0008] In addition, the stress shielding phenomenon caused by differences in elastic modulus is also pointed out as a problem. The elastic modulus of human bone is generally 30 GPa or less, whereas the elastic modulus of pure Ti is approximately 100 GPa. This difference can cause bone loss around the implant, leading to revision surgery.

[0009] To improve this, a Ti-13Nb-13Zr alloy was proposed. The Ti-13Nb-13Zr alloy has the disadvantage that while the elastic modulus decreases during solution heat treatment, the strength also decreases simultaneously, whereas during aging treatment, the strength increases but the elastic modulus also increases.

[0010] A conventional method for cold working Ti-13Nb-13Zr alloys with a cross-sectional reduction rate of 50-70% is known. This method has the disadvantage of a large variation in hardness between the inside and outside of the Ti-Nb-Zr alloy.

[0011] In addition, a method is known in which a Ti-13Nb-13Zr alloy is solution heat-treated at 1000°C for 1 hour, water-cooled, cold-worked with a cross-sectional reduction of about 50%, and then solution heat-treated again at 1000°C for 1 hour and water-cooled. However, this method has the disadvantage of low strength.

[0012] In addition, a method is known in which a Ti-13Nb-13Zr alloy is subjected to solution heat treatment to induce a martensitic structure, followed by compression / rolling at approximately 600°C. This method has the disadvantage of a high elastic modulus.

[0013] In addition, a method is known in which the Ti-13Nb-13Zr alloy is solution heat treated at 800°C for 1 hour, water-cooled, and then aged at 300-700°C. This method has the disadvantage of low strength.

[0014] In addition, ASTM F1713-08 describes a method of aging a Ti-13Nb-13Zr alloy at 481-509°C for 5.35-6.25 hours after solution heat treatment. However, this method has the disadvantage of a high elastic modulus.

[0015] Meanwhile, Korean Patent Publication No. 10-2020-0121531 (published on October 26, 2020) also discloses a method of heating a Ti-13Nb-13Zr alloy at 700°C to 900°C for 30 minutes to 2 hours and water-cooling it to induce a martensitic structure, followed by a multi-pass caliber-rolling process at -196°C to 300°C. Although this method can lower the elastic modulus, it has the disadvantages of a large hardness variation between the inside and outside of the alloy, a complex process, and being unsuitable for mass production.

[0016] The problem that the present invention aims to solve is to provide a high-strength Ti-Nb-Zr alloy having uniform hardness and a low elastic modulus.

[0017] In addition, the problem that the present invention aims to solve is to provide a method for manufacturing a high-strength Ti-Nb-Zr alloy having uniform hardness and a low elastic modulus.

[0018] A method for manufacturing a Ti-Nb-Zr alloy according to the present invention for solving the above problem comprises: a step of manufacturing a Ti-Nb-Zr alloy having an alloy composition comprising Nb: 12.5-14 wt% and Zr: 12.5-14 wt%, and the remainder being Ti and unavoidable impurities, wherein the method comprises: (a) a step of manufacturing a Ti-Nb-Zr alloy base material having the alloy composition; (b) a step of cold working the Ti-Nb-Zr alloy base material at a temperature of 450°C or lower; and (c) a step of heat treating at a temperature of 450°C or lower.

[0019] In some embodiments, between steps (a) and (b), a step of processing the Ti-Nb-Zr alloy base material at a temperature of 800°C or higher and then cooling it may be additionally included.

[0020] In some embodiments, step (b) may be performed at a temperature of room temperature to 400°C.

[0021] In some embodiments, step (b) may be performed under conditions of a cross-sectional reduction rate of 50% or more.

[0022] In some embodiments, step (b) may be performed by drawing.

[0023] In some embodiments, step (c) may be performed at 200-400°C.

[0024] In some embodiments, the step (c) may be performed for 1 to 24 hours.

[0025] The Ti-Nb-Zr alloy according to the present invention for solving the above problem has an alloy composition comprising Nb: 12.5-14 wt% and Zr: 12.5-14 wt%, with the remainder being Ti and unavoidable impurities, and has a microstructure comprising a main phase including both α' phase and α" phase, and a second phase including a β phase with a smaller area ratio than the main phase.

[0026] In some embodiments, regarding the hardness at multiple points in the thickness or diameter direction of the Ti-Nb-Zr alloy, the maximum hardness is H max , minimum hardness H min When saying that, the value determined by the following Equation 1 may be 5 or less.

[0027] [Equation 1]

[0028] (H max -H min ) / H max *100

[0029] In some embodiments, the Ti-Nb-Zr alloy may have a microstructure in which the combined area ratio of the α' phase and α" phase is 80% or more and the area ratio of the β phase is 20% or less.

[0030] In some embodiments, the Ti-Nb-Zr alloy may exhibit an elastic modulus of 65 GPa or less. In some embodiments, the Ti-Nb-Zr alloy may exhibit a yield strength of 850 MPa or more. In some embodiments, the Ti-Nb-Zr alloy may exhibit a tensile strength of 950 MPa or more. In some embodiments, the Ti-Nb-Zr alloy may exhibit an average Vickers hardness of 280 Hv or more.

[0031] The present invention can overcome the limitations of existing Ti-Nb-Zr alloys and provide a high-strength Ti-Nb-Zr alloy having a low elastic modulus and excellent hardness uniformity.

[0032] In particular, the present invention enables the realization of a low elastic modulus along with the resolution of hardness non-uniformity in Ti-Nb-Zr alloys by performing post-heat treatment under specific conditions after cold working. Therefore, since the Ti-Nb-Zr alloy according to the present invention can exhibit high strength along with the effects of suppressing hardness variation and a low elastic modulus, when utilized, for example, as a material for dental implants, it can suppress not only vertical fractures caused by insufficient strength but also parallel fractures caused by hardness variation, and is effective in reducing peri-implant bone loss caused by stress shielding phenomena.

[0033] Therefore, the Ti-Nb-Zr alloy according to the present invention is suitable for use as a medical biomaterial, such as a dental implant material or an orthopedic implant material, or as a corrosion-resistant material for aerospace or chemical plants.

[0034] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below.

[0035] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below.

[0036] With reference to the drawings, various aspects of the present invention are illustrated in detail in an exemplary rather than limiting manner:

[0037] FIG. 1 is a flowchart schematically illustrating a method for manufacturing a high-strength Ti-Nb-Zr alloy having uniform hardness and a low elastic modulus according to an embodiment of the present invention.

[0038] Figure 2 shows the radial hardness measurement locations of the rod applied to the examples and comparative examples.

[0039] Figure 3 shows the results of measuring the diameter-direction hardness of the rods of Ti-Nb-Zr alloys according to Examples 1 to 6.

[0040] Figure 4 shows the results of measuring the diameter-direction hardness of the rods of Ti-Nb-Zr alloys according to Comparative Examples 1 to 4.

[0041] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be implemented in various modified forms by those skilled in the art.

[0042] Throughout this specification, the same reference numerals refer to the same or similar components. The drawings may not be scaled to scale and may be exaggerated to more clearly depict certain features. The terminology used herein is for describing embodiments and is not intended to limit the disclosure.

[0043] Hereinafter, preferred embodiments of a high-strength Ti-Nb-Zr alloy having uniform hardness and a low elastic modulus and a method for manufacturing the same according to the present specification will be described in detail with reference to the attached drawings.

[0044] The inventor of the present invention discovered through extensive research that by using a Ti-Nb-Zr alloy, which has superior biocompatibility to pure Ti, and performing cold working and post-heat treatment under specific conditions, it is possible to manufacture a high-strength Ti-Nb-Zr alloy that not only has a small elastic modulus but also has a small variation in radial hardness.

[0045] FIG. 1 is a flowchart schematically illustrating a method for manufacturing a high-strength, high-ductility Ti-Nb-Zr alloy having uniform hardness and a low elastic modulus according to an embodiment of the present invention.

[0046] Referring to FIG. 1, a method for manufacturing a Ti-Nb-Zr alloy according to an embodiment of the present invention includes a step of manufacturing a Ti-Nb-Zr alloy base material (S110), a cold working step (S120), and a post-heat treatment step (S130).

[0047] Additionally, referring to FIG. 1, a method for manufacturing a Ti-Nb-Zr alloy according to another embodiment of the present invention further includes a hot working and quenching step (S115) prior to a cold working step, and comprises a step for manufacturing a Ti-Nb-Zr alloy base material (S110), a hot working and quenching step (S115), a cold working step (S120), and a post-heat treatment step (S130).

[0048] First, in the step of manufacturing a Ti-Nb-Zr alloy base material (S110), a Ti-Nb-Zr alloy base material is manufactured to produce a Ti-Nb-Zr alloy having a predetermined alloy composition.

[0049] Ti-Nb-Zr alloy base material can be manufactured by methods such as vacuum arc melting (VAM), vacuum induction melting (VIM), vacuum plasma arc melting (PAM), and vacuum electron beam melting (EB). The Ti-Nb-Zr alloy base material may be in the form of, for example, ingots or billets. The Ti-Nb-Zr alloy base material used in the present invention may be solution treated.

[0050] The alloy composition of the Ti-Nb-Zr alloy base material may be substantially the same as the alloy composition of the Ti-Nb-Zr alloy according to the present invention. The Ti-Nb-Zr alloy according to the present invention has an alloy composition containing 12.5-14 wt% of niobium (Nb), 12.5-14 wt% of zirconium (Zr), and the remainder being Ti and unavoidable impurities, and the Ti-Nb-Zr alloy base material may also have the same alloy composition as above. Representative examples of such Ti-Nb-Zr alloys are Ti-13Nb-13Zr alloys. Hereinafter, the roles and contents of each component included in the Ti-Nb-Zr according to the present invention will be described.

[0051] Niobium (Nb)

[0052] In the Ti-Nb-Zr alloy according to the present invention, niobium (Nb) is a representative β-stabilizing element and contributes to stabilizing the α" phase based on the β phase or metastable β phase at room temperature, thereby contributing to lowering the elastic modulus of the Ti-Nb-Zr alloy and also contributing to the improvement of yield strength and toughness. In addition, niobium (Nbr) contributes to improving the biocompatibility of titanium (Ti) together with zirconium (Zr).

[0053] It is preferable that the above Nb be contained in an amount of 12.5-14 wt% relative to 100 wt% of the Ti-Nb-Zr alloy, more preferable that it be contained in an amount of 12.7-13.5 wt%, and most preferable that it be contained in an amount of 12.9-13.2 wt%. If the amount of Nb added is less than 12.5 wt%, it is difficult to fully exert the effect of the addition. On the other hand, if the amount of Nb added exceeds 14 wt%, the β phase may be excessively stabilized, which may suppress the formation of the α" phase and cause problems such as brittle fracture.

[0054] Zirconium (Zr)

[0055] In the Ti-Nb-Zr alloy according to the present invention, zirconium (Zr) contributes to grain refinement and homogenization, improves mechanical strength compared to pure Ti, and also contributes significantly to enhancing excellent biocompatibility through a low elastic modulus.

[0056] The above Zr is preferably contained in an amount of 12.5-14 wt% relative to 100 wt% of the Ti-Nb-Zr alloy, more preferably in an amount of 12.7-13.5 wt%, and most preferably in an amount of 12.9-13.2 wt%. If the amount of Zr added is less than 12.5 wt%, it is difficult to fully exhibit the effect of the addition. On the other hand, if the amount of Zr added exceeds 14 wt%, problems such as reduced elongation, reduced impact toughness, and reduced machinability may occur. In particular, when the amount of Zr added is about 13 wt%, it has a low elastic modulus value, and if it is less than 12.5 wt% or exceeds 14 wt%, the elastic modulus value increases again.

[0057] inevitable impurities

[0058] In addition to the above niobium (Nb) and zirconium (Zr), the remainder may include Ti and unavoidable impurities.

[0059] Unavoidable impurities may include hafnium (Hf) and oxygen (O). Since hafnium (Hf) has a very strong bond with zirconium (Zr), when zirconium (Zr) is added, trace amounts of hafnium (Hf) are also added. When Zr is added at a content of approximately 13% by weight, Hf may be included in an amount of approximately 0.2 to 0.45% by weight. In addition, since excessive oxygen (O) may make cold working impossible, it is desirable to keep the content below 0.3% by weight. Other unavoidable impurities may include C, N, H, etc.

[0060] The above-mentioned unavoidable impurities may be included in an amount of 1% by weight or less, more preferably 0.7% by weight or less, and most preferably 0.5% by weight or less.

[0061] Next, in the cold working step, the Ti-Nb-Zr alloy base material is cold worked. Cold working can increase the strength of the Ti-Nb-Zr alloy.

[0062] It is preferable that cold working be performed at a temperature of 450°C or lower, and more preferable that it be performed at a temperature between room temperature and 400°C or lower. If the cold working temperature exceeds 450°C, a problem may arise in which the elastic modulus of the Ti-Nb-Zr alloy increases significantly.

[0063] In addition, cold working can preferably be performed under conditions of a cross-sectional reduction rate of 50% or more, for example, 50-90%, more preferably under conditions of a cross-sectional reduction rate of 55-85%, and most preferably under conditions of a cross-sectional reduction rate of 60-80%. If the cross-sectional reduction rate of cold working is less than 50%, it may be difficult to secure the target strength.

[0064] Meanwhile, to increase the strength of the Ti-Nb-Zr alloy, etc., if necessary, a step (S115) of hot working the Ti-Nb-Zr alloy base material at a temperature above the β transformation temperature, for example, 800°C or higher, and then rapidly cooling it, such as by water cooling or oil cooling, for example, quenching, may be additionally included prior to cold working. These hot working and rapid cooling steps (S115) may be omitted. In addition, solution treatment may be performed after hot working.

[0065] Next, the post-heat treatment step (S130) includes a step of heat-treating the cold-worked Ti-Nb-Zr alloy. In the case of the cold-worked Ti-Nb-Zr alloy, while strength is improved, there is a problem with a somewhat large variation in hardness. A large variation in hardness can cause parallel fracture of the implant. Such variation in hardness can be reduced without a significant decrease in strength through post-heat treatment under specific conditions.

[0066] Post-heat treatment can preferably be performed at 450°C or lower, and more preferably at 200-400°C. If the post-heat treatment temperature exceeds 450°C, a problem may arise in which the elastic modulus of the Ti-Nb-Zr alloy increases significantly. Meanwhile, if the post-heat treatment temperature is less than 150°C, the effect of reducing hardness variation may be insufficient; therefore, it is preferable that the post-heat treatment temperature be 150°C or higher, and more preferable that it be 200°C or higher.

[0067] Meanwhile, it is preferable that the post-heat treatment be performed for 1 to 24 hours. If the post-heat treatment time is less than 1 hour, the effect of reducing hardness variation through post-heat treatment may be insufficient. On the other hand, even if the post-heat treatment time exceeds 24 hours, no further effect of reducing hardness variation may occur.

[0068] Through the above process, a Ti-Nb-Zr alloy having the characteristics described below can be manufactured.

[0069] A Ti-Nb-Zr alloy according to one embodiment of the present invention may have an alloy composition containing 12.5-14 wt% of Zr and Nb, respectively, and the remainder being Ti and unavoidable impurities. Additionally, the Ti-Nb-Zr alloy according to one embodiment of the present invention may have a microstructure comprising a main phase containing both the α' phase and the α" phase, and a second phase containing the β phase with a smaller area ratio than the main phase. In the present invention, a sufficient α" phase may be included due to the high Nb content and the co-presence of Zr, which is desirable in terms of low elastic modulus. Meanwhile, if hot working and rapid cooling steps are included, the formation of the α' phase can be promoted, which is advantageous in terms of strength. In the present invention, through cooling processing under specific conditions and subsequent heat treatment, the hardness variation can be reduced while suppressing the increase in the elastic modulus.

[0070] Preferably, the Ti-Nb-Zr alloy may have a microstructure in which the combined area ratio of the α' phase and α" phase is 80% or more, and the area ratio of the β phase is 20% or less. Through this area ratio of the α' phase + α" phase and the β phase, high strength and a low elastic modulus can be achieved.

[0071] And, according to one embodiment of the present invention, the Ti-Nb-Zr alloy, through post-heat treatment under specific conditions, has a maximum hardness H at a plurality of points in the thickness or diameter direction of the Ti-Nb-Zr alloy. max , minimum hardness H min When said, the value determined by the following formula 1 is 5 or less, more preferably 4 or less, and most preferably 3 or less.

[0072] [Equation 1]

[0073] (H max -H min ) / H max *100

[0074] In the above Equation 1, the maximum hardness and minimum hardness may each be, for example, based on Vickers hardness, but are not limited thereto.

[0075] Equation 1 above can be seen as an equation representing the hardness deviation, and it can be seen that the lower the value, the smaller the hardness deviation, and the higher the value, the larger the hardness deviation.

[0076] In addition, the Ti-Nb-Zr alloy according to the present invention can exhibit a yield strength of 850 MPa or more, a tensile strength of 950 MPa or more, and an elastic modulus of 65 GPa or less as a result of performing cold working at a temperature of 450°C or lower with a cross-sectional reduction rate of 50% or more and performing post-heat treatment at a temperature of 450°C or lower.

[0077] In addition, the Ti-Nb-Zr alloy according to the present invention can exhibit an average Vickers hardness of 280 Hv or higher, more preferably 290 Hv or higher.

[0078] In the case of the present invention, by controlling the cold working and post-heat treatment conditions of the Ti-Nb-Zr alloy, it is possible to simultaneously obtain high strength, along with the resolution of hardness non-uniformity and securing a low elastic modulus, which were difficult to solve with conventional technology.

[0079] The Ti-Nb-Zr alloy produced by the manufacturing method of the present invention can secure excellent mechanical properties such as a yield strength of 850 MPa or more, a tensile strength of 950 MPa or more, an elastic modulus of 65 GPa or less, and a hardness deviation of 5% or less. This allows for the suppression of parallel fractures and the reduction of bone loss around implants caused by stress shielding phenomena.

[0080] Examples

[0081] The present invention will be explained in more detail below through examples. However, it should be noted that the examples described below are intended only to illustrate and further specify the present invention, and are not intended to limit the scope of the present invention.

[0082] <Example>

[0083] Ingots for manufacturing Ti-13Nb-13Zr alloy were manufactured using a vacuum arc melting method.

[0084] As a result of measuring the content of Nb and Zr at the upper, middle, and lower points along the length of the ingot, Nb was 12.7-13.6 wt% (average 13.2 wt%) and Zr was 12.9-13.5 wt% (average 13.1 wt%), and the alloy composition satisfied the component range specified in ASTM F1713-08.

[0085] In Examples 1-6, a rod-shaped Ti-Nb-Zr alloy was prepared by hot working and solution heat treatment of an ingot at 800°C, which is above the beta transformation temperature, followed by drawing (cold working) at room temperature (RT), 300°C, or 400°C as listed in Table 1 with a cross-sectional reduction rate of 50%, 70%, or 90%, and then post-heat treatment conditions of 1 hour, 6 hours, 12 hours, or 24 hours at 200°C, 300°C, or 400°C.

[0086] Table 1 shows the results of the characteristic evaluation of the Ti-Nb-Zr alloy prepared by the method according to Examples 1-6.

[0087] Tensile strength and yield strength were measured by tensile testing according to ASTM-E8 / E8M standards.

[0088] The elastic modulus was measured using the ASTM E1875-20a method.

[0089] Hardness was measured using a Vickers hardness tester. Figure 2 shows the radial hardness measurement locations applied to the examples and comparative examples. Hardness was measured at five locations in the radial direction as shown in Figure 2 and is shown in Table 1 and Figure 3.

[0090] The hardness deviation was calculated based on the following Equation 1 and is shown in Table 1.

[0091] [Equation 1]

[0092] (H max-H min ) / H max *100

[0093] H max : Maximum hardness, H min : Lowest hardness

[0094] [Table 1]

[0095]

[0096] Referring to Table 1 and Figure 3, the Ti-Nb-Zr alloy specimens according to Examples 1 to 6, which satisfy the cold working and post-heat treatment conditions presented in the present invention—that is, cold working at a temperature of 450°C or lower and post-heat treatment at 450°C—showed results with an elastic modulus of 65 GPa or less and a hardness deviation of 5% or less. In addition, the Ti-Nb-Zr alloy specimens according to Examples 1 to 6 exhibited high strength characteristics, such as a yield strength of 850 MPa or more and a tensile strength of 9500 MPa or more.

[0097] <Comparative Example>

[0098] In Comparative Examples 1-4, a rod-shaped Ti-Nb-Zr alloy was prepared under the cold working and post-heat treatment conditions listed in Table 2.

[0099] In Comparative Example 1-4, an ingot having the alloy composition used in Example 1-6 was used.

[0100] Table 2 and Figure 4 show the results of the characteristic evaluation of Ti-Nb-Zr alloys prepared by the method according to Comparative Examples 1-4.

[0101] [Table 2]

[0102]

[0103] Referring to Table 2 and Figure 4, in the case of the method according to Comparative Example 1, only 50% processing was performed at room temperature and no post-heat treatment was performed. As a result, good strength characteristics and a low elastic modulus were obtained, but the hardness variation was 7.5%, which is significantly higher than that of Examples 1-6. Based on this, it can be seen that post-heat treatment at 450°C or lower, as in Examples 1-6, is necessary to reduce the hardness variation of the Ti-Nb-Zr alloy.

[0104] In addition, Comparative Example 2, in which the post-heat treatment temperature was low at 100°C, exhibited good strength characteristics, but the hardness deviation was 8.3%, which was very high compared to Examples 1-6. This means that if the post-heat treatment temperature is too low, there is almost no effect in reducing the hardness deviation. From these results, it can be seen that the post-heat treatment temperature needs to exceed 100°C.

[0105] In addition, in the case of Comparative Example 3, which had a high cold working temperature of 500℃, the hardness variation was low at 2.5% through post-heat treatment, but the elastic modulus was 81 GPa, showing a significantly higher result compared to Examples 1-6. From these results, it can be seen that the cold working temperature needs to be less than 500℃.

[0106] In the case of Comparative Example 4, where the post-heat treatment temperature was 500℃, the hardness variation was good at about 2.9%, but the elastic modulus was 78 GPa, showing a significantly higher result compared to Examples 1-6. This means that the post-heat treatment temperature needs to be less than 500℃.

[0107] When comparing the examples and comparative examples, the manufactured Ti-Nb-Zr alloy can simultaneously satisfy an elastic modulus of 65 GPa or less and a hardness deviation of 5% or less when the cold working and post-heat treatment conditions presented in the present invention are satisfied. Furthermore, it can be seen that the Ti-Nb-Zr alloy according to the present invention can have excellent strength characteristics, such as a yield strength of 850 MPa or more and a tensile strength of 950 MPa or more.

[0108] Although the present invention has been described above with reference to embodiments, various changes and modifications can be made by those skilled in the art. Therefore, it should be understood that such changes and modifications are included within the scope of the present invention as long as they do not depart from the scope of the invention.

Claims

1. A method for manufacturing a Ti-Nb-Zr alloy having an alloy composition comprising Nb: 12.5-14 wt% and Zr: 12.5-14 wt%, and the remainder being Ti and unavoidable impurities, wherein (a) a step of manufacturing a Ti-Nb-Zr alloy base material having the above alloy composition; (b) a step of cold working a Ti-Nb-Zr alloy base material at a temperature of 450°C or lower; and (c) A method for manufacturing a Ti-Nb-Zr alloy comprising the step of heat treating at a temperature of 450℃ or lower.

2. In Paragraph 1, A method for manufacturing a Ti-Nb-Zr alloy, further comprising, between steps (a) and (b), a step of processing and solution heat treating the Ti-Nb-Zr alloy base material at a temperature of 800°C or higher, and then cooling.

3. In Paragraph 1, A method for manufacturing a Ti-Nb-Zr alloy, wherein step (b) above is performed at a temperature of room temperature to 400°C.

4. In Paragraph 1, A method for manufacturing a Ti-Nb-Zr alloy, wherein the above step (b) is performed under conditions of a cross-sectional reduction rate of 50% or more.

5. In Paragraph 1, The above step (b) is performed by a drawing method, a method for manufacturing a Ti-Nb-Zr alloy.

6. In Paragraph 1, A method for manufacturing a Ti-Nb-Zr alloy, wherein step (c) above is performed at 200-400℃.

7. In Paragraph 1, A method for manufacturing a Ti-Nb-Zr alloy, wherein the above step (c) is performed for 1-24 hours.

8. As a Ti-Nb-Zr alloy, It has an alloy composition comprising Nb: 12.5-14 wt% and Zr: 12.5-14 wt%, with the remainder being Ti and unavoidable impurities, and A Ti-Nb-Zr alloy having a microstructure comprising a columnar phase containing both α' and α" phases, and a second phase containing a β phase with an area ratio smaller than that of the columnar phase.

9. In Paragraph 8, Regarding the hardness of multiple points in the thickness or diameter direction of the above Ti-Nb-Zr alloy, the maximum hardness is H max , minimum hardness H min A Ti-Nb-Zr alloy in which the value determined by the following Equation 1 is 5 or less. [Equation 1] (H max -H min ) / H max *100 10. In Paragraph 8, The above Ti-Nb-Zr alloy is a Ti-Nb-Zr alloy having a microstructure in which the combined area ratio of the α' phase and α" phase is 80% or more and the area ratio of the β phase is 20% or less.

11. In Paragraph 8, The above Ti-Nb-Zr alloy is a Ti-Nb-Zr alloy exhibiting an elastic modulus of 65 GPa or less, a yield strength of 850 MPa or more, a tensile strength of 950 MPa or more, and an average Vickers hardness of 280 Hv or more.

12. A dental implant material comprising a Ti-Nb-Zr alloy according to claim 8.

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