Nitrogen impurity gettering in oxide dispersion ductilized chromium

M. P. Brady; I. M. Anderson; M. L. Weaver; H. M. Meyer; L. R. Walker; M. K. Miller; D. J. Larson; I. G. Wright; V. K. Sikka; A. Rar; G. M. Pharr; J. R. Keiser; C. A. Walls

doi:10.1016/S0921-5093(03)00324-1

Nitrogen impurity gettering in oxide dispersion ductilized chromium

M. P. Brady, I. M. Anderson, M. L. Weaver, H. M. Meyer, L. R. Walker, M. K. Miller, D. J. Larson, I. G. Wright, V. K. Sikka, A. Rar, G. M. Pharr, J. R. Keiser, C. A. Walls

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Abstract

Work by Scruggs in the 1960s demonstrated that tensile ductility could be achieved at room temperature in powder metallurgically-produced Cr alloyed with MgO. During consolidation, much of the MgO converted to the MgCr₂O₄ spinel phase, which was hypothesized to getter nitrogen from the Cr, rendering it ductile. We have duplicated this effect, achieving room temperature tensile elongations of 4% for hot-pressed Cr-6MgO-(0-1)Ti (wt.%) and 10% for hot-pressed and extruded Cr-6MgO-0.75Ti. Direct incorporation of nitrogen into the MgCr₂O₄ phase was not detected; however, impurities, particularly nitrogen and sulfur, were observed to segregate to and/or precipitate at interfaces between the MgO/MgCr₂O₄ phases and the Cr matrix. Exploratory studies of other non-spinel forming oxide dispersions (La₂O₃, TiO₂ and Y₂O₃) showed a similar pattern of impurity segregation/precipitation, suggesting that there is nothing unique about spinel dispersions in Cr with regards to impurities. However, none of these other dispersions resulted in similar levels of tensile elongation.

Original language	English
Pages (from-to)	243-254
Number of pages	12
Journal	Materials Science and Engineering: A
Volume	358
Issue number	1-2
DOIs	https://doi.org/10.1016/S0921-5093(03)00324-1
State	Published - Oct 15 2003

Funding

The authors are indebted for the generosity of Dr. D.M. Scruggs in supplying samples of his alloy for study and for many enlightening discussions. The authors thank P.F. Becher, E.P. George, D. Hoelzer, M. Janney, C.T. Liu, R.J. Lauf, J.H. Schneibel and M. Yoo for many helpful discussions and comments on this manuscript. This research was sponsored by the US Department of Energy, Fossil Energy Advanced Research Materials (ARM) Program and the Office of Industrial Technology (OIT) Forest Products Program. The Oak Ridge National Laboratory (ORNL) SHaRE Collaborative Research Center is also gratefully acknowledged. ORNL is managed by UT-Battelle, LLC for the US Department of Energy under contract DE-AC05-00OR22725.

Funders	Funder number
Arm
Fossil Energy Advanced Research Materials
Office of Industrial Technology
US Department of Energy
Oak Ridge National Laboratory	DE-AC05-00OR22725
Ontario Innovation Trust

Keywords

Composites
Cr
Embrittlement
Mechanical properties
ODS
Powder processing
Segregation

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title = "Nitrogen impurity gettering in oxide dispersion ductilized chromium",

abstract = "Work by Scruggs in the 1960s demonstrated that tensile ductility could be achieved at room temperature in powder metallurgically-produced Cr alloyed with MgO. During consolidation, much of the MgO converted to the MgCr2O4 spinel phase, which was hypothesized to getter nitrogen from the Cr, rendering it ductile. We have duplicated this effect, achieving room temperature tensile elongations of 4% for hot-pressed Cr-6MgO-(0-1)Ti (wt.%) and 10% for hot-pressed and extruded Cr-6MgO-0.75Ti. Direct incorporation of nitrogen into the MgCr2O4 phase was not detected; however, impurities, particularly nitrogen and sulfur, were observed to segregate to and/or precipitate at interfaces between the MgO/MgCr2O4 phases and the Cr matrix. Exploratory studies of other non-spinel forming oxide dispersions (La2O3, TiO2 and Y2O3) showed a similar pattern of impurity segregation/precipitation, suggesting that there is nothing unique about spinel dispersions in Cr with regards to impurities. However, none of these other dispersions resulted in similar levels of tensile elongation.",

keywords = "Composites, Cr, Embrittlement, Mechanical properties, ODS, Powder processing, Segregation",

author = "Brady, {M. P.} and Anderson, {I. M.} and Weaver, {M. L.} and Meyer, {H. M.} and Walker, {L. R.} and Miller, {M. K.} and Larson, {D. J.} and Wright, {I. G.} and Sikka, {V. K.} and A. Rar and Pharr, {G. M.} and Keiser, {J. R.} and Walls, {C. A.}",

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AU - Brady, M. P.

AU - Anderson, I. M.

AU - Weaver, M. L.

AU - Meyer, H. M.

AU - Walker, L. R.

AU - Miller, M. K.

AU - Larson, D. J.

AU - Wright, I. G.

AU - Sikka, V. K.

AU - Rar, A.

AU - Pharr, G. M.

AU - Keiser, J. R.

AU - Walls, C. A.

PY - 2003/10/15

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N2 - Work by Scruggs in the 1960s demonstrated that tensile ductility could be achieved at room temperature in powder metallurgically-produced Cr alloyed with MgO. During consolidation, much of the MgO converted to the MgCr2O4 spinel phase, which was hypothesized to getter nitrogen from the Cr, rendering it ductile. We have duplicated this effect, achieving room temperature tensile elongations of 4% for hot-pressed Cr-6MgO-(0-1)Ti (wt.%) and 10% for hot-pressed and extruded Cr-6MgO-0.75Ti. Direct incorporation of nitrogen into the MgCr2O4 phase was not detected; however, impurities, particularly nitrogen and sulfur, were observed to segregate to and/or precipitate at interfaces between the MgO/MgCr2O4 phases and the Cr matrix. Exploratory studies of other non-spinel forming oxide dispersions (La2O3, TiO2 and Y2O3) showed a similar pattern of impurity segregation/precipitation, suggesting that there is nothing unique about spinel dispersions in Cr with regards to impurities. However, none of these other dispersions resulted in similar levels of tensile elongation.

AB - Work by Scruggs in the 1960s demonstrated that tensile ductility could be achieved at room temperature in powder metallurgically-produced Cr alloyed with MgO. During consolidation, much of the MgO converted to the MgCr2O4 spinel phase, which was hypothesized to getter nitrogen from the Cr, rendering it ductile. We have duplicated this effect, achieving room temperature tensile elongations of 4% for hot-pressed Cr-6MgO-(0-1)Ti (wt.%) and 10% for hot-pressed and extruded Cr-6MgO-0.75Ti. Direct incorporation of nitrogen into the MgCr2O4 phase was not detected; however, impurities, particularly nitrogen and sulfur, were observed to segregate to and/or precipitate at interfaces between the MgO/MgCr2O4 phases and the Cr matrix. Exploratory studies of other non-spinel forming oxide dispersions (La2O3, TiO2 and Y2O3) showed a similar pattern of impurity segregation/precipitation, suggesting that there is nothing unique about spinel dispersions in Cr with regards to impurities. However, none of these other dispersions resulted in similar levels of tensile elongation.

KW - Composites

KW - Cr

KW - Embrittlement

KW - Mechanical properties

KW - ODS

KW - Powder processing

KW - Segregation

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Nitrogen impurity gettering in oxide dispersion ductilized chromium

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