1993 Fiscal Year Final Research Report Summary
Evaluation of performance characteristics and improvement of applicability by making composite of intermetallic compound for high temperature structural material
| Project/Area Number |
02402048
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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 |
溶接工学
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| Research Institution | Osaka University |
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Principal Investigator |
MUKAI Yoshihiko Osaka Univ., Faculty of Eng., Prof., 工学部, 教授 (20029044)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIMURA A. National Institute for Fusion Science, Associate Prof., 核融合科学研究所, 助教授 (60156099)
MURATA M. Osaka Univ., Faculty of Eng., Associate Prof., 工学部, 助教授 (20030059)
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| Project Period (FY) |
1990 – 1993
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| Keywords | Intermetallic compound / Titanium aluminide / Corrosion resistance / Ion implantation |
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| Research Abstract |
Intermetallic compounds in the Ti-Al system are expected to be used as a new material in high temperature environments, but it's still very difficult to fulfilll the required performance characteristics. In the present investigation, the strength, fracture toughness, oxidation and hot corrosion resistance of TiAl intermetallic compounds were studied.
As the results, it is made clear that the strength of plain specimen of TiAl intermetallic compounds is influenced considerably by heat treatment. In as cast samples thin Ti_3Al layrs precipitate and the strength of the interface between TiAl and Ti_3Al is low, so the fracture strength is low in as cast samples. The fracture strength increases by heat treatment, but the fracture strength decreases by the heat treatment at still higher temperatures. The fracture strength is depend on the microstructure changed by the heat treatment and the effect of heat treatment on fracture strength is well described by Larson-Miller Parameter, P.Furthermore, the susceptibilities of oxidization and hot corrosion were evaluated. TiAl intermetallic compound was oxidized at temperatures higher than 1073K and the susceptibility of hot corrosion became remarkable at temperatures higher than 1173K, which results from the selective corrosion of Ti_3Al phase. The oxidation resistance is improved by plasma sprayd ceramic coating. Furthermore, the corrosion resistance of TiAl is much improved by nitrogen ion implantation. Nitride of TiN is produced on the surface of TiAl and the improvement of corrosion resistance is due to the formation of the nitride and solution of nitrogen in TiAl.
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