| Budget Amount *help |
¥17,160,000 (Direct Cost: ¥13,200,000、Indirect Cost: ¥3,960,000)
Fiscal Year 2020: ¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000)
Fiscal Year 2019: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2018: ¥9,490,000 (Direct Cost: ¥7,300,000、Indirect Cost: ¥2,190,000)
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| Outline of Final Research Achievements |
Relationship between the precipitation of delta-Ni3Nb (D0a) phase and eta-Ni3Ti (D024) phase and the lattice misfit between the delta(eta) phases and the Ni (fcc) matrix phase were investigated in model Ni-Cr-Mo-Nb and Ni-Cr-Mo-Ti based alloys to aim at designing polycrystalline Ni based alloys with better temperature capability. Discontinuous precipitation (DC) tends to occur at lower temperatures while continuous precipitation (CP) dominates at higher temperatures in the two alloy systems. The addition of Mo promotes CP with respect to DC while that of Ti promotes DC rather than CP in delta phase precipitation alloys. A replacement of Ti with Mo promotes CP with respect to DP in eta phase precipitation alloys at 800 degree C. The observed effects are discussed in terms of chemical driving force, interfacial energy between the matrix phase and the delta(eta) phases, and coherency strain caused by the formation of the metastable phases prior to the formation of delta(eta) phases.
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