| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1998: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 1997: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1996: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
High-temperature compression test have been conducted on polycrystalline Ir_x Ni_x Alintermetallic compounds with x varying from O to 0.8. Although IrAl(x=0)fractures without exhibiting appreciable yielding at temperatures up to 873K, a steady state-like deformation in IrAl takes place at temperatures higher than range. The IrAl alby exhibits the 0.2% flow stress of 1200MPa at 1037K and 350MPa at 1473K, having negative temperature dependence of the strength. is improved with increasing x, On the contrary the strength decreases with increasing x in the intermediate temperature range. The IrAl alby exhibits the 02% flow stress of 1200MPa at 1073K and 350MPa at 1473K having negative temperature dependence of The strength. Furthermore, the specific strength of Ir1-xNl almost dose not with x=0 to 0.8 at temperatures higher than that of binary NiAl over the entire temperature range to 1473K The 0.2 flow stress Ir_<0.2>Ni_<0.8>Al is significantly higher than that of binary NiAl over the entir
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e temperature range In 1673K Creep rates for polycrystalline (Ni, Ir)A1 are about 2 orders of magnitude lower than those for polycrystalline NiAl. The increment of internal stress of (Ni, Ir)Al contributes greatly to the improvement of creep strength for NiAl. TEM observations in deformed polycrystalline (Ni, Ir)Al show the existence of dislocation network consisting of dislocations with deferent Burgers vector. Creep deformation of single crystal (Ni, Ir)Al exhibits two macroscopically deferent , odes, such as uniform deformation and kinking. We assume that the IR addition inhibits the easy slip system for NiAl and contributes to the formation of sessile dislocation in polycrystalline(Ni, Ir)Al and the phenomenon of kinking in single crystal (Ni, Ir)Al. Ir addition may inhibit the easy slip system{011|<100>for NiAl. Instead, it may facilitate {001}<010>slip system, resulting in the formation of sessile dislocations and subgrain boundary dislocation networks responsible for the high internal stress of (Ni, Ir)Al. Less
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