1990 Fiscal Year Final Research Report Summary
Rapidly Solidified Shape Memory Alloys Produced by Low Pressure Plasma Spraying.
| Project/Area Number |
01460216
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属加工(含鋳造)
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| Research Institution | Osaka University |
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Principal Investigator |
OKAMOTO T. Institute of Scientific and Industrial Research, Professor, 産業科学研究所, 教授 (60029840)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUSHITA K. Institute of Scientific and Industrial Research, Technical Staff, 産業科学研究所, 教務職員 (10150351)
MURAKAMI K. Institute of Scientific and Industrial Research, Assistant Professor, 産業科学研究所, 講師 (60112067)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Shape Memory Alloy / Plasma Spraying / Martensitic Transformation / Rapid Solidification |
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| Research Abstract |
The propose of the present work is to reduce the microsegragation in TiNi shape memory alloys by rapidly solidifying them and to know the effect of the rapid solidification on the martensitic transformation of the alloys. The rapid solidification is performed by low pressure plasma spraying, in which the cooling rate of the alloy melts during solidification is much higher than in melt spinning.
Experimental Procedure : Two kinds of powders are used for spraying. Powder A is a composite powder and each of the powder particles has a layer structure of a nickel phase and a titanium phase. The Ni/(Ni+Ti) ratio is 50.6%. Powder B is an alloy powder containing 49.1AT%Ni. These powders are low pressure plasma sprayed onto substrates having different cooling abilities.
Results : (1) Powder A : Although it was expected that the nickel phase and the titanium phase melt and react with each other to form a TiNi phase, the phase is not detected. The inter-metallic compounds in the deposit layer are Ni_3 Ti and NiTi_2 phases.
(2) Powder B : The deposit layers contain a TiNi phase and martensite, irrespective of the cooling ability of the substrate. The ratio of the amount of martensite to that of the TiNi phase at room temperature is smaller in the deposit layers than in the spray powder. The heat liberated from a given amount of the TiNi phase on martensitic transformation is also smaller in the deposit layers, and decreases with decreasing cooling ability of the substrate. In some areas of the deposit layers, the grain size of the TiNi phase is extremely small, being well below 1muM. The martensitic transformation in such areas will be depressed and the total amount of martensite in the deposit layers will be reduced.
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