| Budget Amount *help |
¥15,200,000 (Direct Cost: ¥15,200,000)
Fiscal Year 2006: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 2005: ¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 2004: ¥8,900,000 (Direct Cost: ¥8,900,000)
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| Research Abstract |
In the present study, for the rapidly solidified ribbons of Ni-42, 46 and 50at%Al, the concentration of supersaturated atomic vacancies was determined and their self-organization behavior was investigated. The lattice parameter of the three kinds of ribbons was refined by analyzing their XRD profiles, and their density was measured by the constant-volume dilatation method. Using the determined lattice parameter and density, the concentration of supersaturated vacancies was estimated for the three kinds of ribbons, indicating that the concentration clearly shows composition dependence. The aging heat treatment of 973 or 1073 K for 10 h was given to the three kinds of the rapidly solidified ribbons, and then surface morphology changes were observed by scanning electron microscopy (SEM). After the aging heat treatment, the nanopore formation near surfaces was confirmed in Ni-46 and 50at%Al, whereas no evident change in surface morphology was observed in Ni-42at%Al. Pore density was higher
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in Ni-50at%Al than in Ni-46at%Al, but there was no significant change in pore density due to the difference of aging temperature in either case. Therefore, it has been clarified that, in rapidly solidified NiAl intermetallic compounds, nanoporous surfaces can be formed by the condensation process of supersaturated vacancies in the similar manner of FeAl intermetallic compound.
The self-organization behavior of supersaturated thermal vacancies was further investigated for Ni-50at%Al single crystal quenched from 1673 K. It was found that nanopores formed near surfaces were faceted by {110} habit planes and accordingly surface morphology in NiAl intermetallic compound formed by the condensation process of supersaturated thermal vacancies was different from that in FeAl intermetallic compound. Furthermore, it was clarified that the pore size and density in NiAl intermetallic compound can be controlled by quenching temperature, aging temperature, aging time in the similar way of FeAl intermetallic compound. Less
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