Oxidation performance of V-Cr-Ti alloys

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Vanadium-base alloys are being considered as candidates for the first wall in advanced V-Li blanket concepts in fusion reactor systems. However, a primary deterrent to the use of these alloys at elevated temperatures is their relatively high affinity for interstitial impurities, i.e., O, N, H, and C. The authors conducted a systematic study to determine the effects of time, temperature, and oxygen partial pressure (pO{sub 2}) in the exposure environment on O uptake, scaling kinetics, and scale microstructure in V-(4--5) wt.% Cr-(4--5) wt.% Ti alloys. Oxidation experiments were conducted on the alloys at pO{sub 2} in the range of 5 ... continued below

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13 p.

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Natesan, K. & Uz, M. April 3, 2000.

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Description

Vanadium-base alloys are being considered as candidates for the first wall in advanced V-Li blanket concepts in fusion reactor systems. However, a primary deterrent to the use of these alloys at elevated temperatures is their relatively high affinity for interstitial impurities, i.e., O, N, H, and C. The authors conducted a systematic study to determine the effects of time, temperature, and oxygen partial pressure (pO{sub 2}) in the exposure environment on O uptake, scaling kinetics, and scale microstructure in V-(4--5) wt.% Cr-(4--5) wt.% Ti alloys. Oxidation experiments were conducted on the alloys at pO{sub 2} in the range of 5 x 10{sup {minus}6}-760 torr (6.6 x 10{sup {minus}4}-1 x 10{sup 5} Pa) at several temperatures in the range of 350--700 C. Models that describe the oxidation kinetics, oxide type and thickness, alloy grain size, and depth of O diffusion in the substrate of the two alloys were determined and compared. Weight change data were correlated with time by a parabolic relationship. The parabolic rate constant was calculated for various exposure conditions and the temperature dependence of the constant was described by an Arrhenius relationship. The results showed that the activation energy for the oxidation process is fairly constant at pO{sub 2} levels in the range of 5 x 10{sup {minus}6}-0.1 torr. The activation energy calculated from data obtained in the air tests was significantly lower, whereas that obtained in pure-O tests (at 760 torr) was substantially higher than the energy obtained under low-pO{sub 2} conditions. The oxide VO{sub 2} was the predominant phase that formed in both alloys when exposed to pO{sub 2} levels of 6.6 x 10{sup {minus}4} to 0.1 torr. V{sub 2}O{sub 5} was the primary phase in specimens exposed to air and to pure O{sub 2} at 760 torr. The implications of the increased O concentration are increased strength and decreased ductility of the alloy. However, the strength of the alloy was not a strong function of the O concentration of the alloy, but an increase in O concentration did cause a substantial decrease in ductility.

Physical Description

13 p.

Notes

INIS; OSTI as DE00754467

Medium: P; Size: 13 pages

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  • 5th International Symposium on Fusion Nuclear Technology, Rome (IT), 09/19/1999--09/24/1999

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  • Report No.: ANL/ET/CP-98334
  • Grant Number: W-31109-ENG-38
  • Office of Scientific & Technical Information Report Number: 754467
  • Archival Resource Key: ark:/67531/metadc710048

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • April 3, 2000

Added to The UNT Digital Library

  • Sept. 12, 2015, 6:31 a.m.

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  • April 7, 2017, 1:09 p.m.

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Natesan, K. & Uz, M. Oxidation performance of V-Cr-Ti alloys, article, April 3, 2000; Illinois. (digital.library.unt.edu/ark:/67531/metadc710048/: accessed January 22, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.