1993 Fiscal Year Final Research Report Summary
Study of the Formation Process of Martensite Nuclei.
| Project/Area Number |
02402045
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical properties of metals
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| Research Institution | University of Tsukuba |
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Principal Investigator |
SUZUKI Tetsurou Univ.Tsukuba, Inst.Appl.Phys.Prof., 物理工学系, 教授 (70045988)
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| Co-Investigator(Kenkyū-buntansha) |
OHSHIMA K. Univ.Tsukuba, Inst.Appl.Phys.Asso.Pro., 物質工学系, 助教授 (70109271)
OTSUKA K. Univ.Tsukuba, Inst.Mat.Sci.Prof., 物質工学系, 教授 (50029881)
HOSHINO T. Univ.Tsukuba, Inst.Struct.Prof., 構造工学系, 教授 (30027130)
TAKANO S. Kyoto Inst.Tech.Eng.Dept.Prof., 工芸学部, 教授 (80027341)
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| Project Period (FY) |
1990 – 1993
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| Keywords | Nucleation / Martensite / Computer simulation / X-ray diffraction / Neutron Diffraction / Incubation time / Elastic constant / Strain dipole |
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| Research Abstract |
The purpose of the present investigation has been to investigate the nucleation process of the martensite by use of computer simulation and X-ray and neutron diffraction experiment.
As the result of computer simulation^<(1,2,7)>, it has become clear that the presence of dislocations with a specific configuration is not required. Either large finite displacement of an atom or presence of a single vacancy can trigger the formation of the martensite nucleus. Also the crystal surface itself can trigger the formation of the martensite nucleus.
In order to investigate the nucleation of the Martensite nucleus in the inside of a crystal, not on the surface of a crystal, X-ray and neutron diffraction methods^<(4,6)> are adopted instead of an electron or optical microscopic method, which has been often traditionally used. The presence of the incubation time has been clearly recognized in all cases studied in the present investigation. At the same time, the presence of any prior sign for the initiation of the martensitic transformation has been clearly ruled out. These results shows that the martensitic transformation is one of typical first order phase transformations^<(3)>..
At the final stage of the present investigation^<(7)>, the decrease of the elastic constant of alloy crystals as the temperature approaches Ms has been found to be caused by the presence of the strain dipoles, which are responsible for the rubber-like behavior found in the aged martensite alloys^<(5)>.
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