2001 Fiscal Year Final Research Report Summary
A Study for Low Carat Gold Alloys with Age-hardenability at Intraoral Temperature
| Project/Area Number |
11671940
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
補綴理工系歯学
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| Research Institution | Nagasaki University |
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Principal Investigator |
HISATSUNE Kunihiro School of Dentistry, Nagasaki University, Professor, 歯学部, 教授 (20037526)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Yasuhiro School of Dentistry, Nagasaki University, Instructor, 歯学部, 助手 (10217086)
SHIRAISHI Takanobu School of Dentistry, Nagasaki University, Assoc. Prof., 歯学部, 助教授 (10150468)
TAKUMA Yasuko School of Dentistry, Nagasaki University, Research Fel., 歯学部, 教務職員 (60160074)
MIURA Eri School of Dentistry, Nagasaki University, Instructor, 歯学部, 助手 (70315258)
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| Project Period (FY) |
1999 – 2001
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| Keywords | dental alloy / gold alloy / superlattice / phase transformation / age-hardening / electron microscope / X-ray diffraction |
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| Research Abstract |
Gold alloys are one of the most useful materials in dental treatment. The required strength is an application of heat treatment wife age4iardening,The hardening is controlled by the formation of ordered phase with L1_0 structure. However, there appears one serious problem of the. deformation on prosthetics, because the L1_0 is different from the matrix phase (fcc) in crystal structure. The purpose of the present study is to clarify the possibility for use of L1_2 phase (fcc) having the same structure. As an L1_2 structure, Cu_3Au and CuAu_3 were selected. Four binary and six ternary alloys were prepared by vacuum-melting in a high-frequency induction furnace. After the solution treatment, two modes were employed, namely anisothermal and isothermal annealings. Th age-hardening behaviors were examined by electrical resistivity measurements, hardness tests, X-ray diffraction and transmission electron microscopy. The main results were as follows ;
(1) It is difficult for only L1_2 phase to obtain appropriate strength for dental prosthetics. Partial introduction of the L1_0 phase (CuAu I) is demanded for the required strength.
(2) Remarkable age-hardening was due to the formation of the CuAu I ordered phase in the Au_3Cu ordered matrix.
(3) Three types of phase transformation in the grain interior from the disordered phase to the equilibrium phases (L1_0 + L1_2) were detected during the isothermal aging. The difference can be interpreted in terms of the free energy.
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