Abstract
This paper provides some insight into an area that has been neglected, namely the possibility of developing high-strength, niobium-base alloys by improved oxidation resistance via the consolidation of rapidly solidified powders. Powder metallurgy (PIM) is an attractive processing technique because of its flexibility and versatility, and it may provide the alloys with properties and workability not obtainable via metal casting. A critical review of both U.S. and Russian literature is presented along with suggestions on the most promising compositions and processing techniques available to meet these competing goals. Previous work on many niobium alloys reveals that long term properties are retained well above those obtained on nickel-base superalloys. Cast and wrought alloys extend specific strength beyond 1200°C (2200°F), but lack oxidation resistance. Remarkable oxidation resistance is obtained, however, on miniature castings of certain ternary alloys which are too brittle for any processing. A better understanding of the oxidation mechanism is necessary before the proper PIM (RST) approach is taken on compositions which could provide compatibility between the two competing goals through grain refinement and a homogeneous distribution of the contributory phases. Finally, ways to upscale production ofNb powder are discussed, including thermodynamic feasibility for the direct reduction of NbCl5 in a 1.5 MW plasma reactor.
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Additional information
E.A. Loria is retired from a 40-year career in both ferrous and non-ferrous metallurgy and is still active as a metallurgical consultant to Niobium Products Company Inc. He is also a senior member of TMS.
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Loria, E.A. Niobium-Base Superalloys via Powder Metallurgy Technology. JOM 39, 22–26 (1987). https://doi.org/10.1007/BF03258035
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DOI: https://doi.org/10.1007/BF03258035