The role of oxygen uptake and scale formation on the embrittlement of vanadium alloys

B. A. Pint; J. R. DiStefano

doi:10.1007/s11085-005-1950-7

The role of oxygen uptake and scale formation on the embrittlement of vanadium alloys

B. A. Pint, J. R. DiStefano

Materials Science and Technology Div

Research output: Contribution to journal › Article › peer-review

28 Scopus citations

Abstract

Vanadium alloys are of interest in fusion energy systems, however, their environmental durability is a major concern. Specimens of V-4Cr-4Ti were exposed to air and oxygen (105 Pa), low pressure (70 ^-3 -10 ^-6 Pa) oxygen and high purity He environments (10 ⁵-10 ¹ Pa) at 500-700°C in order to characterize the surface oxide, determine oxidation kinetics and quantify effects on mechanical properties at 25 and 600°C. At low oxygen pressures (Po ₂≤10 ^-5 Pa), linear reaction kinetics were measured for exposures up to 2000 hr and the data were used to develop a mathematical expression for the oxidation rate as a function of temperature and oxygen pressure. At higher pressures, linear-parabolic reaction kinetics were associated with high oxygen uptake and the formation of an external oxide layer. Room-temperature and 600°C tensile ductility was reduced by these exposures, but specimens which formed an external oxide were found to retain some tensile ductility after exposure. However, similar specimens with an external oxide that were subsequently annealed for 2000 hr at 700°C became severely embrittled demonstrating that a surface oxide will not prevent degradation of this refractory alloy. Exposures in He were performed to determine the effect of total gas pressure on oxygen uptake.

Original language	English
Pages (from-to)	33-55
Number of pages	23
Journal	Oxidation of Metals
Volume	63
Issue number	1-2
DOIs	https://doi.org/10.1007/s11085-005-1950-7
State	Published - Feb 2005

Funding

While writing this paper, the authors were reminded of our indebtedness to J. H. DeVan for many years of collaboration on this project and many others before his death in 2001. At ORNL, P. M. Rice performed the TEM and EELS analysis, H. M. Meyer performed the AES analysis and L. D. Chitwood, L. T. Gibson, K. S. Reeves and J. W. Jones also assisted with the experimental work. P. F. Tortorelli, S. J. Pawel and S. J. Zinkle provided useful comments on the manuscript. The research was sponsored by the Office of Fusion Energy Sciences, U.S. Department of Energy (DOE), under contract DE-AC05-00OR22725 with UT-Battelle, LLC.

Keywords

Environmental effects
Mechanical properties
Oxide dissolution
Refractory metal
Vanadium alloy

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10.1007/s11085-005-1950-7

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title = "The role of oxygen uptake and scale formation on the embrittlement of vanadium alloys",

abstract = "Vanadium alloys are of interest in fusion energy systems, however, their environmental durability is a major concern. Specimens of V-4Cr-4Ti were exposed to air and oxygen (105 Pa), low pressure (70 -3 -10 -6 Pa) oxygen and high purity He environments (10 5-10 1 Pa) at 500-700°C in order to characterize the surface oxide, determine oxidation kinetics and quantify effects on mechanical properties at 25 and 600°C. At low oxygen pressures (Po 2≤10 -5 Pa), linear reaction kinetics were measured for exposures up to 2000 hr and the data were used to develop a mathematical expression for the oxidation rate as a function of temperature and oxygen pressure. At higher pressures, linear-parabolic reaction kinetics were associated with high oxygen uptake and the formation of an external oxide layer. Room-temperature and 600°C tensile ductility was reduced by these exposures, but specimens which formed an external oxide were found to retain some tensile ductility after exposure. However, similar specimens with an external oxide that were subsequently annealed for 2000 hr at 700°C became severely embrittled demonstrating that a surface oxide will not prevent degradation of this refractory alloy. Exposures in He were performed to determine the effect of total gas pressure on oxygen uptake.",

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AU - DiStefano, J. R.

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N2 - Vanadium alloys are of interest in fusion energy systems, however, their environmental durability is a major concern. Specimens of V-4Cr-4Ti were exposed to air and oxygen (105 Pa), low pressure (70 -3 -10 -6 Pa) oxygen and high purity He environments (10 5-10 1 Pa) at 500-700°C in order to characterize the surface oxide, determine oxidation kinetics and quantify effects on mechanical properties at 25 and 600°C. At low oxygen pressures (Po 2≤10 -5 Pa), linear reaction kinetics were measured for exposures up to 2000 hr and the data were used to develop a mathematical expression for the oxidation rate as a function of temperature and oxygen pressure. At higher pressures, linear-parabolic reaction kinetics were associated with high oxygen uptake and the formation of an external oxide layer. Room-temperature and 600°C tensile ductility was reduced by these exposures, but specimens which formed an external oxide were found to retain some tensile ductility after exposure. However, similar specimens with an external oxide that were subsequently annealed for 2000 hr at 700°C became severely embrittled demonstrating that a surface oxide will not prevent degradation of this refractory alloy. Exposures in He were performed to determine the effect of total gas pressure on oxygen uptake.

AB - Vanadium alloys are of interest in fusion energy systems, however, their environmental durability is a major concern. Specimens of V-4Cr-4Ti were exposed to air and oxygen (105 Pa), low pressure (70 -3 -10 -6 Pa) oxygen and high purity He environments (10 5-10 1 Pa) at 500-700°C in order to characterize the surface oxide, determine oxidation kinetics and quantify effects on mechanical properties at 25 and 600°C. At low oxygen pressures (Po 2≤10 -5 Pa), linear reaction kinetics were measured for exposures up to 2000 hr and the data were used to develop a mathematical expression for the oxidation rate as a function of temperature and oxygen pressure. At higher pressures, linear-parabolic reaction kinetics were associated with high oxygen uptake and the formation of an external oxide layer. Room-temperature and 600°C tensile ductility was reduced by these exposures, but specimens which formed an external oxide were found to retain some tensile ductility after exposure. However, similar specimens with an external oxide that were subsequently annealed for 2000 hr at 700°C became severely embrittled demonstrating that a surface oxide will not prevent degradation of this refractory alloy. Exposures in He were performed to determine the effect of total gas pressure on oxygen uptake.

KW - Environmental effects

KW - Mechanical properties

KW - Oxide dissolution

KW - Refractory metal

KW - Vanadium alloy

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The role of oxygen uptake and scale formation on the embrittlement of vanadium alloys

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