Mechanism of Improvement in Oxidation Resistance of TiAl-Based Alloys by Heat Treatment under a Low Partial Pressure Oxygen Atmosphere
| Project/Area Number |
02650514
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属材料(含表面処理・腐食防食)
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| Research Institution | Yokohama National University |
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Principal Investigator |
YOSHIHARA Michiko (1991) Yokohama National University Engineering Research Associate, 工学部, 助手 (70111705)
田中 良平 (1990) 横浜国立大学, 工学部, 教授 (80016188)
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| Co-Investigator(Kenkyū-buntansha) |
吉原 美知子 横浜国立大学, 工学部, 助手 (70111705)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1991: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1990: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Intermetallic compound / TiAl / Oxidation resistance / Surface treatment / Heat treatment under a low partial pressure oxygen atmosphere |
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| Research Abstract |
Oxidation resistance of TiAl-based alloys in static air and its improvement by heat treatment under a low partial pressure oxygen atmosphere was studied to elucidate the mechanism of the treatment. Surface layer formed on the specimen during oxidation or the treatment was investigated by means of X-ray analysis, EPMA or AES. The oxidation resistance in air was better and the effect of the treatment was maintained longer in the specimen with higher aluminum content than that in the case with less aluminum content. It is presumed that the higher aluminum content of the TiAl is considered to promote the formation of Al_2O_3. The diffraction patterns obtained from the specimen oxidized in air at 800ﾟC were almost the same to that with the treatment, except that TiO_2 is identified in the former case. In the case of oxidation in air, since TiO_2 has a large growth compared to Al_2O_3 and diffusion coefficient of aluminum in TiAl is very small, continuous Al_2O_3 layer can not be formed during oxidation. On the other hand, though TiO_2 is formed as well as Al_2O_3, it grows very slowly under a low partial pressure oxygen atmosphere. TiO_2 is hardly formed in aluminum depletion region, Ti_3Al, because of the solubility of oxygen in Ti_3Al, however, Al_2O_3 is expected to be formed in aluminum rich Ti_3Al. Thus, dense and continuous Al_2O_3 layer grows as a result of selective oxidation of aluminum under a low partial pressure oxgen atmosphere. The effect of the treatment is attributed to the Al_2O_3 layer formed during the treatment.
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Report
(3 results)
Research Products
(8 results)
