1991 Fiscal Year Final Research Report Summary
Characterization of Interfaces in Dental Alloys by HREM
| Project/Area Number |
03044117
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Nagasaki University School of Dentistry |
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Principal Investigator |
YASUDA Katsuhiro Professor, Department of Dental Mateials Science, Nagasaki University School of Dentistry,, 歯学部, 教授 (50013884)
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| Co-Investigator(Kenkyū-buntansha) |
TENDELOO G.V アントワープ大学, 超高圧電子顕微鏡センター, 教授
LANDUYT J.Va アントワープ大学, 超高圧電子顕微鏡センター, 教授
TANAKA Yasuhiro Research Associate, Department of Dental Materials Science, Nagasaki University, 歯学部, 助手 (10217086)
UDOH Koh-ichi Research Associate, Department of Dental Materials Science, Nagasaki University, 歯学部, 助手 (60145266)
HISATSUNE Kunihiro Associate Professor, Department of Dental Materials Science, Nagasaki University, 歯学部, 助教授 (20037526)
VAN LANDUYT Joseph Professor, Center of High Voltage Electron Microscopy for Materials Research, Un
VAN TENDELOO Gustaah Professor, Center of High Voltage Electron Microscopy for Materials Research, Un
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| Project Period (FY) |
1991
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| Keywords | Gold alloy / Phase transformation / AuCu II superlattice / AuCu I superlattice / Transmission electron microscopy / High resolution electron microscopy / Electron diffraction / 高分解能電子顕鏡観察 |
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| Research Abstract |
The eventual purpose of the present research project is the tailoring of new dental alloys by scientific designing principle which is governed by microstructural features of the alloy crystals based on an interfacial characterization approach.
Identification of phases formed by phase transformation in a series of alloys from 50at. %Au and 50at. %Cu to Ag was studied by means of electrical resistivity, X-ray diffraction, conventional transmission electron microscopy and high resolution electron microscopy combined with selected area electron diffraction technique. Addition of Ag to AuCu alloy reduced the critical temperatures of ordering of AuCu II and AuCu I at the composition region outside of the Ag-Cu binodal line in AuCu-Ag pseudobinary system. A disordered solid solution of f. c. c. alpha_0 phase which was predicted from the phase rule was found adjacent to a tip of microtwin- platelets when they were in contact with another orientation variants of the microtwin platelets as an ine
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vitable consequence of strain accommodation in AuCu-1.5at. %Ag and AuCu-3at. %Ag alloys. Although an adjacent region of a tip of microthin platelet by arcuation in AuCu-3at. %Ag alloy, such arcuation was never observed at the adjacent region of microthin platelet tip contacted with another variants of microthin platelets in AuCu-1.5at. %Ag alloy. A structural configuration of nucleous formed by ageing was analysed and depicted as a composite nucleous consisted of AuCu II and alpha_0 phases from HREM images. The boundary between alpha_0 + AuCu II and AuCu II also sloped downward for Ag content to the binormal K line. In Au-50at. %Cu stoichiometric composition alloy, the occurrence of spinodal ordering at around 630K was implied from difference in heat treatment mode between a direct ageing from disordered solid solution and tempered ageing after quenching. Ordering wasinduced by nucleation and growth mechanism at a temperature above 630K, while the ordering was originated homogeneously from the mechanism of spinodal ordering. Less
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