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Columbium Alloy Development With Boron, Hafnium, and Tungsten.
Babitzke-HR; Oden-LL; Kelly-HJ
NTIS: PB 192 416 :30 pages
As part of a continuing project to develop refractory metal alloys for high-temperature structural applications, the Bureau of Mines applied solid solution and precipitation strengthening techniques to improve the properties of columbium alloys. The purpose was to investigate the effects of hafnium, tungsten, and boron on the formability, strength, and oxidation resistance of columbium. The experiment was of factorial design with two replications which called for 72 ingots of 36 basic compositions, weighing 150 grams each. Hafnium, tungsten, and boron were evaluated at 3, 3, and 4 levels, respectively. Values of alloy content are all in atomic percent. The highest strength observed was 29,000 psi at 1,200 deg. C for alloys cb-15hf, cb-7.5Hf- 5w-2b, and cb-15hf-5w-2b. At 1,200 deg. C, the ternary alloy cb- 15hf-5w which has shown good properties in previous Bureau of Mines investigations was the most resistant to oxidation. For boron additions, the alloys oxidized more readily with increasing amounts of this element. The fabricability of the alloys high in boron became increasingly difficult, resulting in an inadequate number of alloys required for a complete statistical analysis for all the tests. As a result of the decrease in ductility, an insufficient quantity of tensile samples was available for a proper analysis for the high-temperature strength data.
IH; Report of Investigation;
NTIS Accession No.
NTIS: PB 192 416
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division