| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2017: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
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| Outline of Final Research Achievements |
The transformation mechanism of the orthorhombic α" phase induced by tempering of the Ti-X-7Al alloy was investigated. Quenching from the β single phase region forms a slight α"-M (martensite) with the residual β phase. Rapid tempering to about 500 ° C using a salt bath or convergent light heating results in the formation of coarse α"-M over the entire surface during heating. After holding for 3 minutes or more, α"-M disappears and changes to fine α" iso due to atomic diffusion. Furthermore, α"-M reverses to the β phase when heated to about 200 ° C. Complex transformation behavior suggests that the free energy of the α phase is spinodal decomposition. It is suggested that the complicated transformation behavior is caused by the thermal stress associated with rapid heat treatment and the spinodal decomposition type free energy of α phase.
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