| Budget Amount *help |
¥24,000,000 (Direct Cost: ¥24,000,000)
Fiscal Year 1985: ¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 1984: ¥9,000,000 (Direct Cost: ¥9,000,000)
Fiscal Year 1983: ¥10,000,000 (Direct Cost: ¥10,000,000)
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| Research Abstract |
A new method for alloy design was established by using electronic parameters, such as d-electron levels of M in the transition metal based alloys. Nickel-base single crystal superalloys, which are Ni-Al-Cr-Ta-W, Ni-Co-Al-Cr-Ta-W, Ni-Al-Cr-Ti-Ta-W and Ni-Al-Cr-ReTa-W systems, were developed by using this method. The results obtained in this project were as follows.
(1) <gamma> / <gamma> ' partitioning ratios of the elements in the superalloys were determined exactly. (2) Compositions of the superalloys containing <gamma> + <gamma> ' eutectic phases could be predicted by using <Md_t> , and the <gamma> / <gamma> +TCP phase boundaries were defined by the <Md_(gamma)> calculated by using the <gamma> / <gamma> ' partitioning rations. (3) In the W-rich alloys, <alpha> -W phase occurred during solid ification deteriorated the creep-rupture properties, while the same phase precipitated finely during creep-test improved the creep-rupture lives. In the Ta-rich alloys, the ductility was large, although the strength was not so high. From these facts, it was implied that the strengthening of <gamma> phases was important for high-temperature strength. (4) Although W deteriorated the corrosion resistance, this property,even in the W-rich alloys, was improved by the addition of Re or Ti. (5) The nickel-base superalloys having the high-temperature performance with respect to the high-temperature strength and corrosion resistance were developed by the d-electron alloy design.
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