摘要 |
PURPOSE: Alloys for columnar grain directionally solidified articles are provided which have at least comparable oxidation resistance relative to single crystal counterparts, and corrosion resistance at least comparable to such alloys, and articles in columnar grain directionally solidified form with superior oxidation resistance than comparable articles and alloys in equiaxed or single crystal form are provided. CONSTITUTION: In a high strength, corrosion resistant, nickel base superalloy adapted for use in columnar grain directionally solidified articles, the superalloy comprises in weight percent of about 12% chromium; 9% cobalt; 1.9% molybdenum; 3.8% tungsten; 5% tantalum; 3.6% aluminum; 4.1% titanium; 0.015% boron; 0.1% carbon; and having no intentional addition (and in any event less than about 0.02) zirconium and no intentional amount of niobium; balance essentially nickel and incidental impurities, and wherein aluminum+titanium is between about 6.5-8%; and includes a matrix containing from about 0.4 to 1.5 vol.% of a phase based on tantalum carbide, the article is characterized by oxidation resistance at 2,000 deg.F of roughly 2.5 times and creep rupture life at 1,400 deg.F of roughly 2.4 times compared to a similar article having a nominal composition of 14 Cr, 4.9 Ti, 1.5 Mo, 3.8 W, 2.8 Ta, 3 Al, 9.5 Co, 0.01 B, 0.02 Zr, 0.1 C, and balance Ni.
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