107 results on '"Mitsuo Niinomi"'
Search Results
2. Antibacterial Cu-Doped Calcium Phosphate Coating on Pure Titanium
- Author
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Qiang Li, Junjie Li, Masaaki Nakai, Ran Zhang, Takayoshi Nakano, Mitsuo Niinomi, and Jinshuai Yang
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Materials science ,Mechanical Engineering ,Antibacterial coating ,technology, industry, and agriculture ,chemistry.chemical_element ,Electrochemical deposition ,Electrolyte ,Cu doped ,Condensed Matter Physics ,Phosphate ,Electrochemistry ,medicine.disease_cause ,Hydroxyapatite ,Biomaterials ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,medicine ,lipids (amino acids, peptides, and proteins) ,General Materials Science ,Amorphous calcium phosphate ,Escherichia coli ,Deposition (law) ,Titanium ,Nuclear chemistry - Abstract
Li Q., Yang J., Li J., et al. Antibacterial Cu-doped calcium phosphate coating on pure titanium. Materials Transactions 62, 1052 (2021); https://doi.org/10.2320/matertrans.MT-M2021005., Cu-doped amorphous calcium phosphate (ACP) coatings were fabricated on the surface of pure titanium (Ti) by electrochemical deposition at initial electrolyte temperatures of 35, 45, and 55°C. The antibacterial activities of the coatings were then evaluated by the plate counting method using Escherichia coli as the indicator. The Cu concentrations on the surfaces of samples are increased from 6.90 to 15.05 mass% as initial electrolyte temperature is increased from 35 to 55°C. The Cu-doped ACP coatings show that they can fully inhibit the growth of E. coli.
- Published
- 2021
3. Further development of mechanically biocompatible metallic biomaterials
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Mitsuo Niinomi
- Published
- 2021
4. Factors Leading to Low Elastic Modulus and Current Status of Medically Applied Research of β-type Ti-Nb-based Alloys
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Mitsuo Niinomi and Masaaki Nakai
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Materials science ,Low elastic modulus ,Composite material ,Current (fluid) - Published
- 2020
5. Relationship between Microstructure and Fatigue Properties of Forged Ti-5Al-2Sn-2Zr-4Mo-4Cr for Aircraft Applications
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Saki Tanaka, Masaaki Nakai, Mitsuo Niinomi, and Toshikazu Akahori
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Materials science ,Mechanics of Materials ,Mechanical Engineering ,Metallurgy ,Materials Chemistry ,Metals and Alloys ,General Materials Science ,Condensed Matter Physics ,Microstructure - Published
- 2020
6. Fatigue Property and Cytocompatibility of a Biomedical Co–Cr–Mo Alloy Subjected to a High Pressure Torsion and a Subsequent Short Time Annealing
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Zenji Horita, Hidetoshi Fujii, Takao Hanawa, Huihong Liu, Mitsuo Niinomi, and Peng Chen
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cytocompatibility ,Materials science ,Annealing (metallurgy) ,Mechanical Engineering ,high pressure torsion ,Alloy ,Torsion (mechanics) ,engineering.material ,Co–Cr–Mo alloy ,Condensed Matter Physics ,Mechanics of Materials ,engineering ,annealing ,General Materials Science ,Composite material ,fatigue property - Abstract
In the present study, we evaluated the effects of high pressure torsion (HPT) and subsequent short time annealing processing on fatigue properties and cytocompatibility of the biomedical Co–Cr–Mo alloy (CCM). Before processing, CCM was solution treated (CCMST) to achieve a microstructure composed of coarse single γ-phase equiaxed grains with no internal strain. Through HPT processing, an inhomogeneous microstructure containing both micro- and nano-scaled grains is obtained in CCM specimens, which were named as CCMHPT, accompanied by high internal strain and extensive ε martensite. Following a subsequent short time annealing, a uniform single γ-phase ultrafine-grained microstructure with small local strain fields dispersed forms in CCM specimens, which were named as CCMHPTA. This microstructure change improves fatigue strength in CCMHPT, and further in CCMHPTA, because of the enhanced crack initiation and/or propagation resistance. For cytocompatibility evaluation, the cells cultured on CCMST show an immobilization tendency, while those cultured on CCMHPT exhibit a locomotion tendency. The cells cultured on CCMHPTA have an intermediate pattern. Compared with CCMST, much larger numbers of cells are proliferated in both CCMHPT and CCMHPTA. All these results demonstrate that the CCMHPTA offers an improved fatigue property and a good cytocompatibility. Therefore, it is promising for use in biomedical applications.
- Published
- 2020
7. Suppression of Grain Boundary α Formation by Addition of Silicon in a Near-β Titanium Alloy
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Masaaki Nakai, Huihong Liu, Mitsuo Niinomi, and Tomonori Kitashima
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β titanium ,Materials science ,Silicon ,Mechanical Engineering ,Alloy ,chemistry.chemical_element ,engineering.material ,Condensed Matter Physics ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Silicide ,engineering ,General Materials Science ,Grain boundary ,Composite material - Published
- 2019
8. Development of Strengthening and Toughening of β-type Titanium Alloys
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Mitsuo Niinomi
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Materials science ,Titanium alloy ,Composite material ,Toughening - Published
- 2019
9. Recent Progress in Research and Development of Metallic Structural Biomaterials with Mainly Focusing on Mechanical Biocompatibility
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Mitsuo Niinomi
- Subjects
010302 applied physics ,Materials science ,Biocompatibility ,Mechanical Engineering ,Zirconium alloy ,Young's modulus ,Nanotechnology ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,symbols.namesake ,Mechanics of Materials ,0103 physical sciences ,symbols ,General Materials Science ,0210 nano-technology - Published
- 2018
10. Transition and Prospect of Biomaterials in Terms of Mechanical Biocompatibility
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Mitsuo Niinomi
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Materials science ,Biocompatibility ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,0210 nano-technology ,01 natural sciences ,0104 chemical sciences ,Biomedical engineering - Published
- 2017
11. Heat Treatment to Improve Fatigue Strength of Friction Stir Welded Ti-6Al-4V Alloy Butt Joint
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Masaaki Nakai, Hidetoshi Fujii, Mitsuo Niinomi, Takashi Ninomiya, Yu Ishida, and Huihong Liu
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010302 applied physics ,Materials science ,Mechanical Engineering ,Metallurgy ,Titanium alloy ,02 engineering and technology ,Welding ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Fatigue limit ,law.invention ,Mechanics of Materials ,law ,0103 physical sciences ,Butt joint ,Friction stir welding ,General Materials Science ,Ti 6al 4v ,0210 nano-technology - Published
- 2017
12. Effect of Solute Oxygen on Compressive Fatigue Strength of Spinal Fixation Rods Made of Ti–29Nb–13Ta–4.6Zr Alloys
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Kengo Narita, Mitsuo Niinomi, Huihong Liu, Yoon Seok Lee, and Masaaki Nakai
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Materials science ,Mechanical Engineering ,0206 medical engineering ,Metallurgy ,chemistry.chemical_element ,Fretting ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,020601 biomedical engineering ,Fatigue limit ,Oxygen ,Rod ,Fixation (surgical) ,chemistry ,Mechanics of Materials ,General Materials Science ,Ti 6al 4v ,0210 nano-technology - Published
- 2016
13. A Novel Method of Antibacterial Evaluation Based on the Inhibition of Hydrogen Sulfide Producing Activities of Salmonella
- Author
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Kaoru Midorikawa, Mitsuo Niinomi, Masaaki Nakai, and Yutaka Midorikawa
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0301 basic medicine ,Salmonella ,Materials science ,Mechanical Engineering ,Hydrogen sulfide ,030106 microbiology ,chemistry.chemical_element ,Condensed Matter Physics ,medicine.disease_cause ,Antimicrobial ,Copper ,Combinatorial chemistry ,03 medical and health sciences ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,medicine ,General Materials Science ,Antibacterial agent - Published
- 2016
14. Evaluation of Antibacterial Activity of Copper by Hydrogen Sulfide-Producing Salmonella
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Masaaki Nakai, Yutaka Midorikawa, Mitsuo Niinomi, and Kaoru Midorikawa
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0301 basic medicine ,Salmonella ,Materials science ,Hydrogen sulfide ,030106 microbiology ,Metals and Alloys ,chemistry.chemical_element ,Iron sulfide ,Condensed Matter Physics ,Antimicrobial ,medicine.disease_cause ,Copper ,03 medical and health sciences ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Materials Chemistry ,medicine ,Antibacterial activity ,Nuclear chemistry - Published
- 2016
15. Differences in Wear Behaviors at Sliding Contacts for β-Type and (α + β)-Type Titanium Alloys in Ringer’s Solution and Air
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Mitsuo Niinomi, Ken Cho, Yoon Seok Lee, Masaaki Nakai, and Kengo Narita
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Materials science ,Mechanics of Materials ,Mechanical Engineering ,Delamination ,Metallurgy ,Abrasive ,Titanium alloy ,General Materials Science ,Ringer's solution ,Adhesive ,Lubricant ,Composite material ,Condensed Matter Physics - Published
- 2015
16. Change in Mechanical Strength and Bone Contactability of Biomedical Titanium Alloy with Low Young’s Modulus Subjected to Fine Particle Bombarding Process
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Yurie Oguchi, Toshikazu Akahori, Tomokazu Hattori, Hisao Fukui, and Mitsuo Niinomi
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Condensed Matter Physics - Published
- 2015
17. Evaluation of Adhesion of Hydroxyapatite Films Fabricated on Biomedical β-Type Titanium Alloy after Immersion in Ringer’s Solution
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Ken Cho, Masaaki Nakai, Mitsuo Niinomi, Junko Hieda, and Ayaka Matsubara
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Adhesion strength ,Materials science ,Mechanics of Materials ,Mechanical Engineering ,Metallurgy ,Immersion (virtual reality) ,Titanium alloy ,General Materials Science ,Ringer's solution ,Adhesion ,Condensed Matter Physics - Published
- 2015
18. Change in Mechanical Strength and Bone Contactability of Biomedical Titanium Alloy with Low Young's Modulus Subjected to Fine Particle Bombarding Process
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Toshikazu Akahori, Mitsuo Niinomi, Hisao Fukui, Tomokazu Hattori, and Yurie Oguchi
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Materials science ,Biocompatibility ,Metals and Alloys ,Modulus ,Titanium alloy ,Young's modulus ,Condensed Matter Physics ,Microstructure ,Fatigue limit ,symbols.namesake ,Mechanics of Materials ,Vickers hardness test ,Materials Chemistry ,symbols ,Texture (crystalline) ,Composite material - Abstract
Beta-type Ti-29Nb-13Ta-4.6Zr (TNTZ), which is a recently developed biomedical titanium alloys, shows a relatively low Young’s modulus of around 60GPa when subjected to a solution treatment. However, our focus in this study was on the practical applications of TNTZ in vivo because its mechanical strength decreases with solution treatment progress. Therefore, we investigated the effect of fine particle bombarding (FPB) on the mechanical properties of TNTZ subjected to a cold-swaging treatment in order to maintain its relatively low Young’s modulus and to improve its mechanical properties. The relative bone contact ratios between the cancellous bones of Japanese white rabbits and column-shaped TNTZ samples subjected to FPB were also evaluated. The microstructure of cold-swaged TNTZ showed a single beta-phase with a marble-like structure. Moreover, its Vickers hardness did not increase remarkably with changes in its diameter, although the average diameter of the beta-grains of solutionized TNTZ ranged from 5.0 to 20 μm, depending on the increase in the holding time of the solution treatment. The Vickers hardness and Young’s modulus of TNTZ subjected to FPB increased at the edge of the specimen surface to be around 70% and 15%, respectively, more than those of cold-swaged TNTZ. Further, the fatigue strength of TNTZ subjected to FPB became significantly higher than that of cold-swaged TNTZ in the high-cycle fatigue life region. Lastly, TNTZ with a rough surface texture (Ra: 0.65μm) showed a relative bone contact ratio of more than 80% after undergoing FPB; this value was significantly higher than that of cold-swaged TNTZ with a very smooth surface texture (Ra: 0.07 μm). [doi:10.2320/matertrans.M2014349]
- Published
- 2014
19. PREFACE
- Author
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Tadashi Furuhara, Takao Hanawa, Hideki Hosoda, Masato Ueda, Takayuki Narushima, Takayoshi Nakano, Yoko Yamabe-Mitarai, and Mitsuo Niinomi
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Materials science ,chemistry ,Mechanics of Materials ,Mechanical Engineering ,chemistry.chemical_element ,General Materials Science ,Condensed Matter Physics ,Construction engineering ,Titanium - Published
- 2019
20. Current Status of Biomedical Materials Development Group
- Author
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Takao Hanawa and Mitsuo Niinomi
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Gerontology ,Group (periodic table) ,business.industry ,Medicine ,Current (fluid) ,business - Published
- 2015
21. Development of Titanium Alloys with High Mechanical Biocompatibility with Focusing on Controlling Elastic Modulus
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Mitsuo Niinomi
- Subjects
Materials science ,Biocompatibility ,Titanium alloy ,Composite material ,Elastic modulus - Published
- 2013
22. Development of High Modulus Ti–Fe–Cu Alloys for Biomedical Applications
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Ken Cho, Masaaki Nakai, Junko Hieda, Yuuki Kawasaki, and Mitsuo Niinomi
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Materials science ,Mechanical Engineering ,Metallurgy ,Alloy ,Intermetallic ,Modulus ,engineering.material ,Condensed Matter Physics ,Microstructure ,Metal ,Compressive strength ,Mechanics of Materials ,visual_art ,Phase (matter) ,Vickers hardness test ,visual_art.visual_art_medium ,engineering ,General Materials Science - Abstract
TiFeCu alloys with higher Young’s modulus, hardness and compressive mechanical properties than those of the existing Ti alloys were developed using a d-electrons alloy design method in order to improve Young’s modulus, hardness and compressive properties of Ti and existing Ti alloys for use as metallic stents. Their microstructures, Young’s modulus, hardness and compressive mechanical properties were investigated both before (as-cast) and after heat-treatments performed under a high-purity argon atmosphere at 1173K for 21.6 and 86.4ks. The studied TiFeCu alloys consist of the ¢-Ti phase and dendritic TiFe intermetallic phase. Moreover, the area fraction of the TiFe intermetallic phase increases with increasing atom ratio (Fe + Cu)/Ti of the alloys and with the heat-treatment time. The Young’s modulus of the studied TiFeCu alloys increases from 110GPa (Ti78Fe18Cu4 alloy) to 145GPa (Ti68Fe30Cu2 alloy) with increasing atom ratio (Fe + Cu)/Ti of the alloys and the area fraction of the TiFe intermetallic phase. However, the Young’s modulus is saturated or slightly decreased when the area fraction of the TiFe intermetallic phase is more than 34%. The Vickers hardness of the as-cast alloys increases from 490HV (Ti78Fe18Cu4 alloy) to 550HV (Ti63.4Fe30Cu6.6 alloy) with increasing atom ratio (Fe + Cu)/Ti of the alloys and area fraction of the TiFe intermetallic phase. On the other hand, the Vickers hardness of the heat-treated alloys is lower than that of the as-cast alloys, despite the increase in the area fraction of the TiFe intermetallic phase after the heat-treatment. The heat-treated alloys have better compressive properties than those of the as-cast alloys and the reported TiFeCu alloys. The compressive strength and strain of the heat-treated Ti67Fe27Cu6 alloys reach to 2131MPa and 24.5%, respectively. [doi:10.2320/matertrans.M2012361]
- Published
- 2013
23. Effects of Alloying Elements on the HAp Formability on Ti Alloys after Alkali Treatment
- Author
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Mitsuo Niinomi, Junko Hieda, Xiaojie Tao, Masaaki Nakai, and Ken Cho
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Materials science ,Mechanics of Materials ,Mechanical Engineering ,Metallurgy ,Titanium alloy ,Formability ,General Materials Science ,Condensed Matter Physics ,Alkali metal - Published
- 2013
24. Effect of Oxide Particles Formed through Addition of Rare-Earth Metal on Mechanical Properties of Biomedical β-Type Titanium Alloy
- Author
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Masaaki Nakai, Mitsuo Niinomi, Ken Cho, Shigeki Nagai, and Junko Hieda
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Materials science ,Mechanical Engineering ,Alloy ,Metallurgy ,Oxide ,chemistry.chemical_element ,Titanium alloy ,Yttrium ,engineering.material ,Condensed Matter Physics ,Fatigue limit ,Grain size ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Ultimate tensile strength ,engineering ,General Materials Science ,Composite material ,Elongation - Abstract
In order to improve the mechanical properties of Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy without increasing Young's modulus for application in bone prostheses, dispersion strengthening of TNTZ using yttrium oxide (Y2O3) particles was studied. The formation of well-dispersed Y2O3 particles inside grains of Y-added TNTZ is achieved through the reaction of added Y with the oxygen contained in TNTZ. The size and its standard deviation of obtained Y2O3 particles increased at Y concentrations of 0.2 and 0.5 mass%. The addition of Y led to a decrease in the grain size in Y-added TNTZ. Low Young's modulus was retained in the Y-added TNTZ subjected to cold rolling. The tensile strength and 0.2% proof stress slightly increased in Y-added TNTZ with Y concentrations below 0.1 mass%, whereas they decreased significantly in Y-added TNTZ with Y concentrations of 0.2 and 0.5 mass%. Large Y2O3 particles that formed in Y-added TNTZ with Y concentrations of 0.2 and 0.5 mass% worked as sources for the formation of voids during fracture, which resulted in a decrease in the tensile strength and 0.2% proof stress. Elongation tended to decrease in the Y-added TNTZ as compared to that of TNTZ without any Y addition. As a result, it is found that Y-added TNTZ with improved mechanical properties was obtained at a Y concentration of 0.05 mass% in this experiment. The fatigue strength of Y-added TNTZ was also improved at the Y concentration of 0.05 mass%.
- Published
- 2013
25. Surface Modification Layer and Mechanical Properties of Biomedical Beta-Type Ti-29Nb-13Ta-4.6Zr Subjected to Friction Stir Process
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Mitsuo Niinomi, Yurie Oguchi, Toshikazu Akahori, Masahiro Fukumoto, Toshiaki Yasui, Hisao Fukui, and Tomokazu Hattori
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Materials science ,Metals and Alloys ,Young's modulus ,Condensed Matter Physics ,Microstructure ,law.invention ,symbols.namesake ,Magazine ,Mechanics of Materials ,law ,Materials Chemistry ,symbols ,Surface modification ,Composite material ,Beta type ,Layer (electronics) - Published
- 2013
26. Improvement of Tensile and Fatigue Properties of β-Titanium Alloy while Maintaining Low Young’s Modulus through Grain Refinement and Oxygen Addition
- Author
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Ken Cho, Mitsuo Niinomi, Ryota Kanekiyo, Masaaki Nakai, and Junko Hieda
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Swaging ,Materials science ,Mechanical Engineering ,Metallurgy ,Alloy ,Modulus ,Young's modulus ,engineering.material ,Condensed Matter Physics ,Microstructure ,Fatigue limit ,symbols.namesake ,Mechanics of Materials ,Ultimate tensile strength ,symbols ,engineering ,General Materials Science ,Texture (crystalline) - Abstract
To investigate methods of improving the tensile and fatigue properties of a solutionized Ti29Nb13Ta4.6Zr (TNTZ) alloy without increasing its Young’ modulus, two types of TNTZ alloys having oxygen contents of 0.06 and 0.14mass% (TNTZ0.06O and TNTZ0.14O), respectively, were subjected to cold swaging and a subsequent heat-treatment. The effects of the grain refinement caused by the cold swaging and the subsequent heat-treatment as well as those of oxygen addition on the microstructures, Young’s moduli and tensile and fatigue properties of the two alloys were investigated. The grain diameters of the TNTZ0.06O and TNTZ0.14O decrease from 27µm (as-received) to 1.7µm and from 33µm (as-received) to 1.0µm, respectively, after subjected to cold swaging and the subsequent heat-treatment. These results suggest that cold swaging, followed by heat treatment, is effective in refining the grains of TNTZ alloys. However, a ¢ (110) texture develops in the alloys as a result of the cold swaging. Young’s moduli of as-cold swaged and heat-treated TNTZ0.06O and TNTZ0.14O are within the range of 6168GPa and as low as those of solutionized TNTZ0.06O and TNTZ0.14O. The tensile strengths and elongations of the as-cold swaged, heat-treated and solutionized TNTZ0.14O are approximately 30% higher and 20% lower, respectively, than those of the corresponding TNTZ0.06O. Moreover, the 0.2% proof stresses of the heat-treated TNTZ0.14O are approximately 110% higher than that of the corresponding TNTZ0.06O. On the other hand, the values of the Hall-Petch constant (k) for the TNTZ0.06O (kTNTZ0.06O = 0.02) and TNTZ0.14O (kTNTZ0.14O = 0.005) are much smaller than those for pure Ti and another ¢-type Ti alloy (Ti15.2Mo). These results indicate that the addition of oxygen can improve the tensile properties of TNTZ alloys. However, the grain refinement caused by cold swaging and a subsequent heat-treatment does not have a significant effect on the tensile properties of TNTZ. The fatigue limit of the heat-treated TNTZ0.14O (540MPa) is much higher than those of the heat-treated and solutionized TNTZ0.06O (290 and 230MPa) and solutionized TNTZ0.14O (330MPa). These results indicated that it is possible to improve the fatigue properties of solutionized TNTZ using grain refinement, which can be induced by cold swaging and a subsequent heat-treatment and by the addition of oxygen. [doi:10.2320/matertrans.M2013151]
- Published
- 2013
27. Relationship between Microstructures and Mechanical Properties in Ti–4.5Al–2Mo–1.6V–0.5Fe–0.3Si–0.03C for Next-Generation Aircraft Applications
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Mitsuo Niinomi, Hideto Oyama, Masaaki Nakai, Yoshio Itsumi, Toshikazu Akahori, Shiro Aki, Shogo Murakami, and Harumi Tsutsumi
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Acicular ,Materials science ,Mechanics of Materials ,Mechanical Engineering ,Metallurgy ,Mechanical strength ,General Materials Science ,Texture (crystalline) ,Composite material ,Condensed Matter Physics ,Anisotropy ,Microstructure - Abstract
The effects of microstructures on the mechanical properties of Ti–4.5Al–2Mo–1.6V–0.5Fe–0.3Si–0.03C (KS Ti-9) were systematically investigated by conducting several heat treatments for next-generation aircraft applications. The mechanical strength of as-received KS Ti-9 exhibits high anisotropy that is derived from the intense texture (T-texture) of the primary α phase. Such high anisotropy is observed in KS Ti-9 annealed at temperatures slightly below β-transus, but it is drastically decreased in KS Ti-9 subjected to an anisotropy controlling treatment. The reduction in the anisotropy for KS Ti-9 is related to the differences in the orientations of the precipitated acicular α phase.
- Published
- 2013
28. Bone Loss and Degradation of Bone Quality in the Human Femur after Total Hip Arthroplasty under Stress-Shielding by Titanium-Based Implant
- Author
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Naoko Ikeo, Takuya Miura, Takuya Ishimoto, Takayoshi Nakano, Yoshihiro Noyama, and Mitsuo Niinomi
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Materials science ,business.industry ,Metals and Alloys ,chemistry.chemical_element ,Dentistry ,Human femur ,Stress shielding ,Condensed Matter Physics ,chemistry ,Mechanics of Materials ,Bone quality ,Materials Chemistry ,Implant ,business ,Titanium ,Total hip arthroplasty - Published
- 2012
29. Bone Loss and Reduced Bone Quality of the Human Femur after Total Hip Arthroplasty under Stress-Shielding Effects by Titanium-Based Implant
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Takuya Miura, Takayoshi Nakano, Yoshihiro Noyama, Takuya Ishimoto, Takahiro Itaya, and Mitsuo Niinomi
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musculoskeletal diseases ,Materials science ,Mechanical Engineering ,medicine.medical_treatment ,chemistry.chemical_element ,Biomaterial ,Stress shielding ,Condensed Matter Physics ,chemistry ,Mechanics of Materials ,Bone quality ,medicine ,General Materials Science ,Femur ,Implant ,Reduction (orthopedic surgery) ,Biomedical engineering ,Total hip arthroplasty ,Titanium - Abstract
The present work was aimed at clarifying the stress-shielding effect caused by hip-joint implantation into a femur by using a human cadaver with a cementless hip implant. In particular, bone quality was assessed from the standpoint of preferential c-axis orientation of biological apatite (BAp). Comparing the implanted side to the non-implanted side, a finite element analysis (FEA) indicated that artificial hip-joint implantation had a significant stress-shielding effect on the femur. The results also showed a marked decrease in the degree of preferential BAp orientation as well as bone loss in the medial-proximal femur. This is the first report showing a reduction in the degree of preferential BAp orientation due to a stress-shielding effect after artificial hip-joint implantation. Since preferential BAp orientation is an important index for determining bone mechanical function, these findings should be taken into account in future artificial hip-joint designs, especially those involving the stem component. [doi:10.2320/matertrans.M2011358]
- Published
- 2012
30. Effect of Deformation-Induced ω Phase on the Mechanical Properties of Metastable β-Type Ti–V Alloys
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Masaaki Nakai, Junko Hieda, Xingfeng Zhao, and Mitsuo Niinomi
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Materials science ,Mechanical Engineering ,Alloy ,Metallurgy ,Titanium alloy ,Young's modulus ,engineering.material ,Condensed Matter Physics ,Microstructure ,symbols.namesake ,Mechanics of Materials ,Phase (matter) ,Ultimate tensile strength ,engineering ,symbols ,General Materials Science ,Deformation (engineering) ,Composite material ,Crystal twinning - Abstract
A series of metastable ¢-type binary Ti(1822)V alloys were prepared to investigate the effect of deformation-induced products (deformation-induced ½ phase transformation and mechanical twinning) on the mechanical properties of metastable ¢-type titanium alloys. The microstructures, Young’s moduli, and tensile properties of the alloys were systemically examined. Ti(1820)V alloys subjected to solution treatment comprise a ¢ phase and a small amount of athermal ½ phase, while Ti22V alloy subjected to solution treatment consists of a single ¢ phase. Ti(1820)V alloys subjected to solution treatment exhibit relatively low Young’s moduli and low tensile strengths as compared to cold-rolled specimens. Both deformation-induced ½ phase transformation and {332}¢h113i¢ mechanical twinning occur in all of the alloys during cold rolling. The occurrences of {332}¢h113i¢ mechanical twinning and deformationinduced ½ phase transformation are dependent on the ¢ stability of the alloys. After cold rolling, all of the alloys comprise a ¢ phase and an ½ phase. The Young’s moduli of Ti(1822)Valloys increase because of the formation of a deformation-induced ½ phase during cold rolling. The significant increase in tensile strength is attributed to the combined effect of the deformation-induced ½ phase transformation and workhardening during cold rolling. [doi:10.2320/matertrans.M2012116]
- Published
- 2012
31. Biomechanical Evaluation of Amorphous Calcium Phosphate Coated TNTZ Implants Prepared Using a Radiofrequency Magnetron Sputtering System
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Risa Uzuka, Keiichi Sasaki, Osamu Suzuki, Naru Shiraishi, Takayuki Narushima, Takahisa Anada, Mitsuo Niinomi, Rong Tu, and Takashi Goto
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Materials science ,Mechanics of Materials ,Mechanical Engineering ,medicine.medical_treatment ,medicine ,General Materials Science ,Amorphous calcium phosphate ,Sputter deposition ,Composite material ,Condensed Matter Physics ,Dental implant ,Osseointegration - Published
- 2012
32. Creation of Functionality by Ubiquitous Elements in Titanium Alloys
- Author
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Mitsuo Niinomi
- Subjects
Materials science ,Metallurgy ,Metals and Alloys ,Titanium alloy ,chemistry.chemical_element ,Interstitial element ,Condensed Matter Physics ,Metal ,chemistry ,Mechanics of Materials ,Impurity ,Aluminium ,visual_art ,Metallic materials ,Materials Chemistry ,visual_art.visual_art_medium ,Titanium - Abstract
The cost of titanium (Ti) and its alloys is still much higher than the costs of steels and aluminum alloys; this has inhibited their widespread usage. It is necessary to reduce their cost in order to make Ti and its alloys common metallic materials, namely, ubiquitous titanium and its alloys for their widespread usage. One of the main reasons for their high cost is that they contain a large amount of high-cost rare metals. Therefore, it is imperative to conduct research and development for producing Ti alloys that utilize low-cost common metal elements such as Si, Al, Fe, Cu, and Sn and interstitial elements such as O, N, H, and C. In this paper, the effects of ubiquitous alloying elements such as interstitial elements, O, N, C, and H, and substitutional elements, Fe and Si, which have been generally treated as impurities on functionalities of titanium alloys are discussed.
- Published
- 2011
33. Mechanical Properties and Frictional Wear Characteristics of Biomedical Zr-20 mass%Nb Alloy Subjected to Surface Hardening Treatment
- Author
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Yusuke Kondo, Tomokazu Hattori, Hisao Fukui, Masaaki Nakai, Toshikazu Akahori, Harumi Tsutsumi, and Mitsuo Niinomi
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Materials science ,Metallurgy ,Alloy ,Metals and Alloys ,Oxide ,Modulus ,engineering.material ,Condensed Matter Physics ,Microstructure ,Exfoliation joint ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Vickers hardness test ,Ultimate tensile strength ,Materials Chemistry ,engineering ,Elongation - Abstract
The frictional wear characteristics, mechanical properties, and biocompatibilities of biomedical Zr-20 mass%Nb alloy (Zr-20Nb) subjected to solution treatment (ST) and air-oxidizing process (AOP) were investigated. Vickers hardness of the specimen surface of Zr-20Nb subjected to AOP at 973 K, 1073 K, and 1123 K are approximately 4.5 times larger than that of Zr-20Nb subjected to ST. Young's modulus of Zr-20Nb subjected to AOP increases with increasing AOP temperature up to 1073 K. 0.2% proof stress, tensile strength, and elongation of Zr-20Nb subjected to each AOP decrease proportionally with increasing AOP temperature, and is inferior to those of Zr-20Nb subjected to ST because of the growth of oxide layer with a large amount of micro-cracks and the diffusion of oxygen into the subsurface. Frictional wear loss of Zr-20Nb subjected to each AOP decreases drastically as compared to that of Zr-20Nb subjected to ST. Bone-compatibility of Zr-20Nb subjected to AOP at 973 K is better than that of AOP at 1073 K because of the existence of some cracks and partial exfoliation of oxide layer.
- Published
- 2011
34. Mechanical Properties and Biocompatibilities of Zr-Nb System Alloys with Different Nb Contents for Biomedical Applications
- Author
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Tomokazu Hattori, Masaaki Nakai, Yusuke Kondo, Hisao Fukui, Toshikazu Akahori, Harumi Tsutsumi, and Mitsuo Niinomi
- Subjects
Materials science ,Metallurgy ,Alloy ,Metals and Alloys ,Modulus ,Biomaterial ,Young's modulus ,engineering.material ,Condensed Matter Physics ,Microstructure ,symbols.namesake ,Mechanics of Materials ,Phase (matter) ,Volume fraction ,Ultimate tensile strength ,Materials Chemistry ,engineering ,symbols - Abstract
The microstructures, mechanical properties, and biocompatibilities of as-solutionized Zr-Nb system alloys with different Nb contents for biomedical applications were investigated. The microstructures of Zr-5 mass%Nb, Zr-10 mass%Nb, and Zr-20 mass%Nb alloys subjected to solution treatment (ST) consist of α′, ω, and β phases while the microstructure of Zr-30 mass%Nb alloy subjected to ST consists of almost all single β phase. Young's modulus of Zr-20 mass%Nb alloy shows the lowest value of 63 GPa among the others alloys although the tensile strength and 0.2% proof stress decrease because of decrease in volume fraction of ω phase while Zr-10 mass%Nb alloy with a large amount of ω phase shows the highest values of Young's modulus, tensile strength, and 0.2% proof stress. The elongations of Zr-20 mass%Nb and Zr-30 mass%Nb alloys show relatively high values of 22% and 24%, respectively. The cell viability and bone-bonding characteristics of Zr-Nb system alloys are improved with increasing Nb content. Therefore, it is considered that Zr-Nb alloys have relatively high biocompatibility and belong to bio-inert metallic biomaterial.
- Published
- 2011
35. Fabrication of Hydroxyapatite Film on Ti-29Nb-13Ta-4.6Zr Using a MOCVD Technique
- Author
-
Takashi Goto, Rong Tu, Toshikazu Akahori, Harumi Tsutsumi, Tatsuya Gozawa, Kazumi Saito, Masaaki Nakai, and Mitsuo Niinomi
- Subjects
Materials science ,Fabrication ,Biocompatibility ,Mechanical Engineering ,Metals and Alloys ,Modulus ,Substrate (chemistry) ,Young's modulus ,Chemical vapor deposition ,Substrate (electronics) ,Condensed Matter Physics ,symbols.namesake ,Mechanics of Materials ,Heating temperature ,Materials Chemistry ,symbols ,Formability ,General Materials Science ,Metalorganic vapour phase epitaxy ,Composite material - Abstract
A hydroxyapatite (HAp) film was fabricated on the surface of Ti-29Nb-13Ta-4.6Zr (TNTZ) using a metal-organic chemical vapor deposition (MOCVD) technique, and the mechanical biocompatibility and HAp formability of HAp-coated TNTZ were evaluated and discussed in this study. HAp film is fabricated on the surface of TNTZ by controlling the heating temperature of the source (bis-dipivaloylmethanatocalcium (Ca(dpm) 2 ) and (C 6 H 5 0) 3 PO). An α-phase precipitates in the TNTZ matrix after heating the substrate, and the mechanical properties and Young's modulus of HAp-coated TNTZ are improved. HAp-coated TNTZ maintains excellent mechanical biocompatibility. The formability of HAp on HAp-coated TNTZ in Hank's balanced salt solution is better than that of HAp on non-coated TNTZ.
- Published
- 2010
36. Relationship between Unique Hardening Behavior and Microstructure of Dental Silver Alloy Subjected to Solution Treatment
- Author
-
Yonghwan Kim, Mitsuo Niinomi, Hisao Fukui, Harumi Tsutsumi, Toru Kanno, Toshikazu Akahori, and Masaaki Nakai
- Subjects
Materials science ,Alloy ,Metallurgy ,Metals and Alloys ,engineering.material ,Solution treatment ,Condensed Matter Physics ,Microstructure ,Solid solution strengthening ,Precipitation hardening ,Mechanics of Materials ,Ultimate tensile strength ,Materials Chemistry ,engineering ,Hardening (metallurgy) - Abstract
The purpose in this study is to investigate the effect of microstructure on the unique hardening behavior of dental silver alloy, Ag-20Pd-14.5Cu-12Au (mass%), fabricated by hot rolling process (AS material), which is in as-received condition, and liquid rapid solidification (LRS) process (LRS material). The following results were obtained. The microstructure of AS material is consisted of α1, α, and β phases. The microstructure of AS material changes to α, β, and β′ phases through a solution treatment (ST). The microstructure of LRS material is consisted of α, α1, and α2 phases without β phase. The microstructure of LRS material becomes single α phase through ST. Relatively large β phases with the diameter of tens of μm on AS material coarsen according to increasing the ST time, while the small those with the diameter of a few μm are solid-soluted into the matrix. On the other hand, the coherent participation of β′ phases with long and short axes of around 100 nm and 10 nm, respectively, also occurs during ST although the amount of β′ phase decreases with increasing the ST time. The hardness and tensile strength of LRS material and LRS material subjected to ST are relatively smaller than those of AS material and AS material subjected to the same treatment. From this results, the effect of solid solution hardening of α, α1, and α2 phases is lower than that of precipitation hardening of β′ phases. In a case of the unique hardening seems to occur because the precipitation of β′ phases are enhanced during ST.
- Published
- 2010
37. Quality Improvement of a β-Type Titanium Alloy Cast for Biomedical Applications by Using a Clacia Mold
- Author
-
Masaaki Nakai, Tsutomu Takeuchi, Mitsuo Niinomi, Harumi Tsutsumi, Shigeki Katsura, and Toshikazu Akahori
- Subjects
Zirconium ,Materials science ,Mechanical Engineering ,Metallurgy ,Titanium alloy ,chemistry.chemical_element ,Surface finish ,Condensed Matter Physics ,medicine.disease_cause ,chemistry ,Mechanics of Materials ,Casting (metalworking) ,Mold ,Volume fraction ,medicine ,General Materials Science ,Shrinkage ,Titanium - Abstract
The applicability of a calcia mold to casting a � -type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), was evaluated with focusing on the dimensional accuracy of the casting in this study. Pure zirconium particles were added to a calcia mold to take advantage of the expansion of oxidized zirconium during the baking process in order to compensate for the solidification shrinkage of TNTZ. The morphological characteristics of the casting surface, such as the roughness and dimensional accuracy, of the cast TNTZ were investigated. The dilation ratio of the calcia mold is found to increase with increasing the number of pure zirconium particles. The addition of 12 mass% or 14 mass% pure zirconium particles compensates for not only the solidification of TNTZ but also the occurrence of shrinkage of the calcia mold. In addition, the formation of a surface reaction layer in TNTZ is restrained to a larger extent by casting into a calcia mold than into a magnesia mold, which is the conventional investment mold for titanium casting. Furthermore, the volume fraction and number of casting defects are also restrained to a larger extent by casting into a calcia mold than into a magnesia mold. The results of this study should lead to enhancements in the creation of cast TNTZ for dental products. [doi:10.2320/matertrans.L-M2009827]
- Published
- 2010
38. Fabrication of Beta-Ti-Type Ti-Nb-Ta-Zr (TNTZ) Wire with High-Ductility by Arc-Melt-Type Melt-Extraction Method
- Author
-
Takeshi Nagase, Takayoshi Nakano, Yukichi Umakoshi, and Mitsuo Niinomi
- Subjects
Fabrication ,Materials science ,Mechanical Engineering ,Metallurgy ,Alloy ,Bending ,engineering.material ,Condensed Matter Physics ,Smooth surface ,Mechanics of Materials ,Beta (plasma physics) ,Ultimate tensile strength ,engineering ,General Materials Science ,Extraction methods ,Ductility - Abstract
Beta-Ti-type Ti-30Nb-10Ta-5Zr (TNTZ) wires with high-ductility were developed using the arc-melt-type melt-extraction method. The continuous melt-extracted wire with very smooth surface and small fluctuations in the diameter realizes the high tensile strength and superior bending ductility of TNTZ alloy. The melt-extracted Beta-Ti wire shows the possibility for the use in biomedical applications. The arc-melt-type melt-extraction method is very effective for developing new Beta-Ti-based biomaterials.
- Published
- 2010
39. Mechanical Properties of a β-Type Titanium Alloy Cast Using a Calcia Mold for Biomedical Applications
- Author
-
Masaaki Nakai, Shigeki Katsura, Tsutomu Takeuchi, Toshikazu Akahori, Harumi Tsutsumi, and Mitsuo Niinomi
- Subjects
Zirconium ,Materials science ,Mechanical Engineering ,Metallurgy ,chemistry.chemical_element ,Titanium alloy ,Condensed Matter Physics ,medicine.disease_cause ,Fatigue limit ,Precision casting ,chemistry ,Mechanics of Materials ,Casting (metalworking) ,Mold ,Ultimate tensile strength ,medicine ,Melting point ,General Materials Science ,Composite material - Abstract
A calcia mold, which is stable at high temperatures for dental precision casting of � -type titanium alloys such as Ti-29Nb-13Ta-4.6Zr (TNTZ) with high melting point, has been developed. The applicability of the calcia mold to casting TNTZ was evaluated with focusing on the mechanical properties of the casting in this study. The molten TNTZ was cast into the calcia mold of which dimensional accuracy was controlled by adding pure zirconium particles. The tensile and fatigue properties of TNTZ cast into the calcia mold were examined with comparing those of TNTZ cast into the magnesia mold, which is the conventional one for casting titanium alloys. The tensile properties of TNTZ cast into the calcia and the magnesia molds are not markedly different. The fatigue strength of TNTZ cast into the calcia mold in the low- and high-cycle fatigue life regions is slightly higher than that of TNTZ cast into the magnesia mold. Therefore, the calcia mold is expected to be applicable to the dental precision casting of TNTZ. [doi:10.2320/matertrans.L-M2009828]
- Published
- 2010
40. Anomalous Thermal Expansion of Cold-Rolled Ti-Nb-Ta-Zr Alloy
- Author
-
Masaaki Nakai, Harumi Tsutsumi, Mitsuo Niinomi, Xiaoliang Feng, Michiharu Ogawa, and Toshikazu Akahori
- Subjects
Materials science ,Mechanical Engineering ,Alloy ,Titanium alloy ,Atmospheric temperature range ,engineering.material ,Physics::Classical Physics ,Condensed Matter Physics ,Thermal expansion ,Negative thermal expansion ,Mechanics of Materials ,engineering ,General Materials Science ,Dilatometer ,Composite material ,Anisotropy ,Shrinkage - Abstract
Negative thermal expansion, i.e. a type of shrinkage that occurs during heating, was observed in cold-rolled Ti-29Nb-13Ta-4.6Zr alloy (mass%) (TNTZ). The reduction ratio of cold rolling and the angle of the longitudinal axis of specimens with respect to the cold-rolling direction were systematically changed, and then the thermal expansion rate was measured using a dilatometer. Further, the cyclicity of thermal expansion was examined for the cold-rolled TNTZ. From the results, it is observed that with an increase in the reduction ratio of cold rolling, the thermal expansion rate of TNTZ cold-rolled parallel to the rolling direction (RD) decreases, but it increases in TNTZ cold-rolled parallel to the transverse direction (TD). With regard to the anisotropy of thermal expansion, the thermal expansion rate increases with the angle between the longitudinal axis of the specimens and RD. Further, the cyclicity of the above-mentioned anomalous thermal expansion is observed in a temperature range below 473 K, but it is not observed when the specimen is heated above 573 K in the first cycle.
- Published
- 2009
41. Effect of Oxygen Content on Microstructure and Mechanical Properties of Biomedical Ti-29Nb-13Ta-4.6Zr Alloy under Solutionized and Aged Conditions
- Author
-
Toshikazu Akahori, Michiharu Ogawa, Harumi Tsutsumi, Masaaki Nakai, and Mitsuo Niinomi
- Subjects
Materials science ,Mechanical Engineering ,Alloy ,Metallurgy ,technology, industry, and agriculture ,chemistry.chemical_element ,Titanium alloy ,Young's modulus ,Interstitial element ,engineering.material ,equipment and supplies ,Condensed Matter Physics ,Microstructure ,Oxygen ,symbols.namesake ,Precipitation hardening ,chemistry ,Mechanics of Materials ,Ultimate tensile strength ,engineering ,symbols ,General Materials Science - Abstract
The effect of oxygen content on the microstructure and mechanical properties of the Ti-29 mass%Nb-13 mass%Ta-4.6 mass%Zr (TNTZ) alloy was investigated in this study. The microstructural observation of TNTZ alloys, containing 0.1-0.4 mass% oxygen, subjected to solution treatment shows the presence of a single β phase. With an increase in oxygen content, the hardness, tensile strength, and Young's modulus of TNTZ alloy increase, but its elongation decreases. Further, the α phase precipitates in TNTZ alloys subjected to aging treatment at 723 K for 259.2 ks. The results of transmission electron microscopy and X-ray diffraction analysis indicate that the size and volume fraction of the α phase increase with oxygen content. Corresponding to the changes in the microstructure, the mechanical properties of TNTZ alloy subjected to aging treatment at 723 K change with oxygen content. The increase in oxygen content leads to enhancement of the age hardening of TNTZ alloy, thereby increasing both tensile strength and Young's modulus of TNTZ alloy, but its elongation decreases due to the α-phase precipitation. The mechanical properties of TNTZ alloy (Young's modulus: around 60-100 GPa, tensile strength: around 600-1400 MPa, and elongation: around 5-25‰) vary significantly depending on oxygen content and heat treatment.
- Published
- 2009
42. Isothermal Aging Behavior of Beta Titanium–Manganese Alloys
- Author
-
Ryoichi Matsunaga, Mitsuo Niinomi, Masahiko Ikeda, Masato Ueda, and Michiharu Ogawa
- Subjects
Materials science ,Precipitation (chemistry) ,Mechanical Engineering ,Metallurgy ,technology, industry, and agriculture ,chemistry.chemical_element ,Titanium alloy ,Manganese ,equipment and supplies ,Condensed Matter Physics ,Isothermal process ,chemistry ,Mechanics of Materials ,Aluminium ,Vickers hardness test ,General Materials Science ,Beta-titanium ,Titanium - Abstract
Although titanium is considered to be a ubiquitous element as it has the 10th-highest Clarke number of all the elements, it is actually classified as a rare metal because the current refinement process for the metal is more environmentally damaging than the processes used to refine iron and aluminum. Furthermore, the principal alloying elements of titanium alloys are very expensive, owing to their low crustal abundances; this is especially true of the beta-stabilizing elements. Manganese is also considered to be a ubiquitous element as it has the 12th-highest Clarke number of all the elements. Therefore, manganese is promising as an alloying element for titanium, especially as a beta-stabilizing element. In order to develop beta titanium alloys as ubiquitous metallic materials, it is very important to investigate the properties of Ti-Mn alloys. In this study, the phase constitutions and isothermal aging behaviors of Ti-6.0 to 14.8 mass%Mn alloys were investigated by electrical resistivity and Vickers hardness measurements, X-ray diffraction (XRD), and optical microscopy. In 6.0 mass%Mn alloys quenched from 1173 K, both hexagonal close-packed martensite and the beta phase were identified by XRD, whereas only the beta phase was detected in 8.7 and 14.8 mass%Mn alloys. The resistivity at liquid nitrogen temperature was greater than that at room temperature between 6.0 and 14.8 mass%Mn. The Vickers hardness decreased with an increase in the Mn content up to 11.3 mass%Mn and then increased slightly. On aging at 673 K, the isothermal omega phase was precipitated in 6.0 to 11.3 mass%Mn alloys, while it was precipitated by aging at 773 K in 6.0 and 8.7 mass%Mn alloys. The Vickers hardness increased drastically on isothermal omega precipitation, whereas it increased slightly in the case of direct alpha precipitation with no isothermal omega precipitation. [doi:10.2320/matertrans.MA200902]
- Published
- 2009
43. Dental Precision Casting of Ti-29Nb-13Ta-4.6Zr Using Calcia Mold
- Author
-
Toshikazu Akahori, Harumi Tsutsumi, Masaaki Nakai, Tsutomu Takeuchi, Shigeki Katsura, and Mitsuo Niinomi
- Subjects
Wax ,Materials science ,Mechanical Engineering ,Alloy ,Metallurgy ,Titanium alloy ,engineering.material ,Condensed Matter Physics ,medicine.disease_cause ,law.invention ,Optical microscope ,Mechanics of Materials ,law ,visual_art ,Mold ,Vickers hardness test ,visual_art.visual_art_medium ,medicine ,engineering ,Slurry ,General Materials Science ,Layer (electronics) - Abstract
The objective of this study is to develop a dental precision casting process for a beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy which has been developed for biomedical applications, using a mold made by electrically fused calcia particles. The effect of a combination of different sizes of calcia particles on the surface condition of the mold was investigated. In addition, to obtain a smooth surface, a cast TNTZ was made using a mold made using a mixture of calcia particles with a wax pattern conducted with calcia slurry coatings. Furthermore, surface reaction layer of the cast TNTZ was evaluated using an optical microscopy, a Vickers' hardness test and a X-ray diffractometry. The surface of the mold fabricated with a mixture of fine (diameter < 0.3 mm) and coarse (diameter = 1-3 mm) calcia particles is smooth and showed no cracks or defects. In addition, the surfaces of the cast TNTZ made using the duplex-coated wax pattern with the fine pure calcia slurry and crushed silica fiber-reinforced fine calcia slurry are very fine. Furthermore, the formation of the surface reaction layer on the cast TNTZ is remarkably inhibited. The results of this study should lead to enhancements in the creation of cast TNTZ for dental products.
- Published
- 2009
44. Biologically and Mechanically Biocompatible Titanium Alloys
- Author
-
Mitsuo Niinomi
- Subjects
Materials science ,Biocompatibility ,Mechanical Engineering ,Metallurgy ,technology, industry, and agriculture ,Titanium alloy ,Fretting ,Bone fracture ,Shape-memory alloy ,equipment and supplies ,Condensed Matter Physics ,medicine.disease ,Biocompatible material ,Mechanics of Materials ,medicine ,General Materials Science ,Composite material - Abstract
Nb, Ta, and Zr are the favorable nontoxic and allergy-free alloying elements suitable for use in titanium alloys for biomedical applications. Low-rigidity titanium alloys composed of nontoxic and allergy-free elements are receiving considerable attention. The advantage of low-rigidity titanium alloys in the healing of bone fracture and bone remodeling is successfully proven by using tibia of rabbit as a fracture model. Ni-free superelastic and shape memory titanium alloys for biomedical applications are being actively developed. The mechanical properties such as fatigue and fretting fatigue are important from the viewpoint of mechanical properties, which may be collectively referred to as mechanical biocompatibilities in the broad sense, in addition to the rigidity, i.e. Young's modulus. Bioactive surface modifications of titanium alloys for biomedical applications are very important for achieving further biocompatibility.
- Published
- 2008
45. Effect of Oxygen Content on Microstructure and Mechanical Properties of Ti-29Nb-13Ta-4.6Zr Alloy for Biomedical Applications
- Author
-
Toshikazu Akahori, Michiharu Ogawa, Hiroshi Ishikawa, Masaaki Nakai, and Mitsuo Niinomi
- Subjects
Materials science ,Metals and Alloys ,Titanium alloy ,Young's modulus ,Interstitial element ,Condensed Matter Physics ,Microstructure ,symbols.namesake ,Solid solution strengthening ,Precipitation hardening ,Mechanics of Materials ,Ultimate tensile strength ,Materials Chemistry ,symbols ,Elongation ,Composite material - Abstract
The effect of oxygen content on the microstructure and mechanical properties of Ti-29Nb-13Ta-4.6Zr (TNTZ) solutionized and aged at 723 K was investigated. The microstructure of solutionized TNTZ consists of a single β phase, and addition of oxygen leads to the increase in the hardness and tensile strength because of solid solution hardening, and the increase in Young's modulus, and the decrease in the elongation. On the other hand, the α phase precipitates in the aged TNTZ. The results of transmission electron microscopy and X-ray diffraction imply that the size and volume fraction of the α phase increase with the oxygen content in the aged TNTZ. The mechanical properties of the aged TNTZ change with the oxygen content. Age hardening in aged TNTZ is enhanced by an increase in the oxygen content. Further, with an increase in the oxygen content, both the tensile strength and Young's modulus increase, while elongation decreases due to the precipitation of the α phase. TNTZ with different mechanical properties (Young's modulus: around 60-100 GPa, tensile strength: around 600-1400 MPa, elongation: around 5-25%) can be obtained depending on the oxygen content and the heat treatment technique.
- Published
- 2008
46. Characteristics of Biomedical Beta-Type Titanium Alloy Subjected to Coating
- Author
-
Toshihiro Kasuga, Toshikazu Akahori, Michiharu Ogawa, Mitsuo Niinomi, and Masaaki Nakai
- Subjects
Zirconium ,Materials science ,Mechanical Engineering ,Simulated body fluid ,Alloy ,Metallurgy ,Titanium alloy ,chemistry.chemical_element ,engineering.material ,Condensed Matter Physics ,Microstructure ,Coating ,chemistry ,Mechanics of Materials ,engineering ,Surface modification ,General Materials Science ,Composite material ,Layer (electronics) - Abstract
Beta-type titanium alloys used in biomedical applications have been developed all over the world. In particular, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) is one of beta-type titanium alloys for biomedical applications that has been developed by the authors in Japan. Although TNTZ is composed of non-toxic elements such as niobium, tantalum, and zirconium, it still lacks bioactivity, which is the ability to form chemical bonds with living bones. The stems that are parts of artificial hip joints, dental implants, etc., which are made of metallic materials, etc. are required to bond strongly with living bones. However, these stems, dental implants etc., cannot form chemical bond with living bones by themselves. The bioactive surface modification of metallic materials by the application of ceramics is effective in improving the biocompatibility of TNTZ. Calcium phosphate ceramics such as hydroxyapatite (Ca 10 (PO 4 ) 6 OH 2 ; HAP) and β-tricalcium phosphate (β-Ca 3 (PΟ 4 ) 2 ; β-TCP) possess bioactivity. In this study, the characteristics and morphology of TNTZ coated with a calcium phosphate invert-glass-ceramic (CPIG) layer by dip-coating treatment or with a sodium titanate layer by alkali solution treatment are investigated before and after soaking it in a simulated body fluid (SBF). The bonding strength between a CPIG layer with a thickness of around 5 μm and a specimen surface of TNTZ is around 25 MPa. No cracks or exfoliations are observed along the boundary between the CPIG layer and the specimen surface. This is the reason why the difference in the thermal expansion coefficients between CPIG layer and TNTZ reduced due to a compositional gradient zone with a thickness of around 3 μm in CPIG layer. HAP is formed on the entire surface of the TNTZ specimen after soaking it in the SBF for more than 1728 ks. The fatigue properties of TNTZ coated with a CPIG layer are similar to those of as-solutionized TNTZ. A reticulate structure with a thickness of 400 to 800 nm is formed on the TNTZ specimen surface after soaking it in 3 to 10 kmol/m 3 NaOH solution for 86.4 ks and 172.8 ks. HAP is completely formed on the entire surface of the TNTZ specimen when it is soaked in the SBF for 1209.6 ks after being soaked in 5 kmol/m 3 NaOH solution for 172.8ks.
- Published
- 2008
47. Fretting-Fatigue Properties and Fracture Mechanism of Semi-Precious Alloy for Dental Applications
- Author
-
Masaaki Nakai, Mitsuo Niinomi, Wataru Kawagishi, Hisao Fukui, and Toshikazu Akahori
- Subjects
Materials science ,Mechanics of Materials ,Alloy ,Metallurgy ,Materials Chemistry ,Metals and Alloys ,engineering ,Fracture (geology) ,Fretting ,engineering.material ,Condensed Matter Physics ,Microstructure ,Mechanism (sociology) - Published
- 2008
48. Wear and Mechanical Properties, and Cell Viability of Gas-Nitrided Beta-Type Ti-Nb-Ta-Zr System Alloy for Biomedical Applications
- Author
-
Hideki Nishimura, Hisao Fukui, Michiharu Ogawa, Masaaki Nakai, Mitsuo Niinomi, Toshikazu Akahori, and Yukiko Takei
- Subjects
Materials science ,Mechanical Engineering ,Simulated body fluid ,Metallurgy ,Alloy ,chemistry.chemical_element ,Titanium alloy ,engineering.material ,Condensed Matter Physics ,Fatigue limit ,chemistry ,Mechanics of Materials ,Vickers hardness test ,Ultimate tensile strength ,engineering ,General Materials Science ,Nitriding ,Titanium - Abstract
Frictional wear resistance is one of the important properties of metallic biomaterials. Surface hardening treatments such as oxidizing, nitriding and ion implantation tend to be applied for improving the wear resistance of titanium and its alloys. The simple gas nitriding process is expected to further improve the wear resistance of newly developed beta-type Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) for biomedical applications. However, there is a possibility for the mechanical properties such as tensile and fatigue strength of TNTZ to be degraded through gas nitriding process. Therefore, the gas nitriding process was carried out in this study to improve the wear resistance of TNTZ and alpha+beta-type Ti-6Al-4V ELI alloy (Ti64), which is one of the representative titanium alloys practically applied for biomedical applications, in simulated body fluid (Ringer's solution). Their tensile and fatigue properties and cell viability was also investigated in order to confirm the reliability as biomedical materials. The Vickers hardness near the specimen surface of nitrided TNTZ and Ti64, where TiN and Ti 2 N forms, increases significantly as compared to that of their matrices. The wear resistances of TNTZ and Ti64 are improved significantly in Ringer's solution by nitriding process as compared to those of as-solutionized TNTZ (TNTZ ST ) and Ti64 (Ti64 ST ). The tensile strength of nitrided TNTZ increases by around 90 MPa as compared to that of TNTZ ST . The tensile strength of nitrided Ti64 does not change significantly at all nitriding temperatures. On the other hand, the elongation decreases with increasing the nitriding temperature. The run out (plain fatigue limit) of TNTZ subjected to a nitriding process at 1123 K, which has relatively good balance between wear resistance and tensile properties, is around 300 MPa, and is nearly equal to that of Ti64 subjected to a nitriding process at 1123 K, although the tensile strength of the nitrided TNTZ is around 200 MPa smaller than that of the nitrided Ti64. The cell viabilities of nitrided TNTZ and Ti64 range from 1.4 to 1.6 against that of control (cell disc), and are a little higher than that of TNTZ ST and Ti64 ST . The cell viabilities of nitrided TNTZ and Ti64 after removing the oxide layer on their surfaces are similar to that of control and are not significantly degraded.
- Published
- 2008
49. Mechanical Properties and Phase Stability of Ti-Nb-Ta-Zr-O Alloys
- Author
-
Tadahiko Furuta, Mitsuo Niinomi, Junghwan Hwang, Kazuaki Nishino, Shigeru Kuramoto, and Takashi Saito
- Subjects
Materials science ,Mechanical Engineering ,Alloy ,Metallurgy ,Niobium ,chemistry.chemical_element ,Work hardening ,engineering.material ,Condensed Matter Physics ,Microstructure ,chemistry ,Mechanics of Materials ,Phase (matter) ,Ultimate tensile strength ,engineering ,General Materials Science ,Deformation (engineering) ,Tensile testing - Abstract
The effects of niobium and oxygen content on the mechanical properties, β phase stability and elastic deformation behavior of Ti-Nb-Ta-Zr-O alloys were investigated by employing tensile tests, microstructure observations and XRD analysis. The basic composition of the tested alloys used was Ti-36%Nb-2%Ta-3%Zr-0.3%O (mass%), with the other alloys having lower niobium content (from 32% to 36%) and higher oxygen content (0.5%). Orthorhombic α″ was observed in the specimens with lower niobium content. Work hardening and elastic deformation behavior in the specimens with lower niobium (33% to 34%) and higher oxygen (0.5%) contents are similar to those of the alloy with basic composition; these specimens showed little work hardening and non-linearity in the elastic range of tensile deformation. The phase configuration analysis of these specimen alloys does not show the presence of any peaks other than the β phase before and after cold working. The cold worked Ti-32%Nb-2%Ta-3%Zr-0.5%O has a Young’s modulus of 55 GPa, a tensile strength of 1370 MPa and a tensile elongation of 12%. After heat treatment at 623 K for 600 s, the tensile strength of the alloy reaches 1500 MPa, with a Young’s modulus of 58 GPa and a tensile elongation of 10%.
- Published
- 2007
50. [Untitled]
- Author
-
Mitsuo Niinomi
- Published
- 2007
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