| Project/Area Number |
23K13574
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 26050:Material processing and microstructure control-related
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| Research Institution | Yokohama National University |
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Principal Investigator |
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| Project Period (FY) |
2023-04-01 – 2025-03-31
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| Project Status |
Completed (Fiscal Year 2024)
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| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2024: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2023: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | High entropy alloy / Microstructure / Medical alloy / Texture / Young's modulus / Medium entropy alloys / Texture control / Biomaterials / Alloy design / Medium entropy alloy / Biomedical material / Hot deformation / Elastic modulus / Crystallographic texture / Biocompatibility |
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| Outline of Research at the Start |
To cop out of stress shielding at a bone-metallic implant interface, the microstructural fabrication with {100} preferred orientation is required for reducing Young’s modulus. In this study, the microstructure of new biocompatible BCC HEA is controlled by using a hot uniaxial compression.
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| Outline of Final Research Achievements |
The newly designed medical medium entropy alloys (MEAs) are Nb30Ti30Zr30Cr5Mo5 and Nb30Ti30Zr30Cr5Ta5 MEAs, presenting a single BCC phase. Initially, after homogenization, the compressive yield stress and uniform compressive strain microhardness of Nb30Ti30Zr30Cr5Mo5 are 1112 MPa and 31%, respectively and those of Nb30Ti30Zr30Cr5Ta5 are 1016 MPa and 38%, respectively. The initial Young’s modulus of Nb30Ti30Zr30Cr5Mo5 and Nb30Ti30Zr30Cr5Ta5 MEAs are 93 and 87 GPa, respectively. Further reduction of Young's modulus was conducted using high temperature compressive deformation to fabricate a strong formation of {001} orientation. An increase in the volume fraction of {001} fiber texture decreases the Young’s modulus. In Nb30Ti30Zr30Cr5Mo5 MEA, the Young’s modulus could reduce to 68 GPa with maximum volume fraction of {001} fiber texture about 64%. In Nb30Ti30Zr30Cr5Ta5 MEA, the minimum Young’s modulus was 61 GPa with the volume fraction of {001} fiber texture about 73%.
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| Academic Significance and Societal Importance of the Research Achievements |
New Nb30Ti30Zr30Cr5Mo5 and Nb30Ti30Zr30Cr5Ta5 alloys are potential for biomedical implant due to higher yield strength (~1000MPa) than medical beta-Ti alloys. Despite initially high Young's modulus (~90GPa), the modulus is reduced to 60-70GPa using texture control of preferred {001} orientation.
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