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Ti-Modified Niobium-Silicide Based Directionally Solidified in-situ Composites

Published online by Cambridge University Press:  15 February 2011

B. P. Bewlay
Affiliation:
General Electric Company, Corporate Research and Development Center, Schenectady, NY 12301
M. R. Jackson
Affiliation:
General Electric Company, Corporate Research and Development Center, Schenectady, NY 12301
H. A. Lipsitt
Affiliation:
Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH 45435.
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Abstract

This paper examines microstructure-property relationships in high-temperature directionally solidified (DS) in-situ composites based on Nb silicides, such as Nb3Si and Nb5Si3. These in-situ composites are based on the Nb3Si-Nb binary eutectic, and are alloyed with Ti. They were prepared using cold crucible Czochralski crystal growth. Ternary Nb-Ti-Si alloys with Ti concentrations from 9 to 45%, and Si concentrations from 10 to 25%, were directionally solidified to generate aligned two- and three-phase composites containing a Nb solid solution with Nb3Si and Nb5Si3 silicides. Fracture toughness values generally greater than 10 MPa√m were measured in these composites. For a given Si concentration, the fracture toughness of the Ti-containing composites was increased ∼ 6 MPa√m over that of the binary alloy composites. The effects of Si concentration, and a range of Nb:Ti ratios, on microstructure, phase equilibria, and fracture toughness were examined.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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