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Microstructural Effects on Ductile Phase Toughening of Nb-Nb Silicide Composites

Published online by Cambridge University Press:  22 February 2011

J. J. Lewandowski ,
D. Dimiduk ,
W. Kerr  and
M. G. Mendiratta
J. J. Lewandowski
Affiliation:
Dept. Matl's Sci. and Eng., Case Western Reserve University, Cleveland, OH 44106
D. Dimiduk
Affiliation:
AFWAL/MLLM, Wright Patterson AFB, Dayton, OH 45433
W. Kerr
Affiliation:
AFWAL/MLLM, Wright Patterson AFB, Dayton, OH 45433
M. G. Mendiratta
Affiliation:
Universal Energy Systems, Inc., Dayton, OH 45432
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Abstract

In the Nb-Si system, the terminal Nb5 Si3 phase and the Nb Si phase are virtually immiscible up to approximately 2033K. This system offers the potential of producing composites consisting of a ductile refractory metal phase and a strong intermetallic phase. In-situ composites containing different volume fractions of the ductile Nb phase were produced via vacuum arc-casting. Microhardness testing as well as smooth bend bar testing was conducted at temperatures ranging from 298K to 1673K in an attempt to determine microstructural effects on the yield strength and smooth bar fracture strength. Notched bend specimens were similarly tested to determine the effects of the ductile phase (i.e. Nb) on enhancing the notched bend toughness. It is shown that the Nb phase often behaves in a ductile manner during testing, thereby toughening the in-situ composite. The mechanism of toughening appears to be due to crack bridging.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 120: Symposium G – High-Temperature/High-Performance Composites , 1988 , 103
Copyright
Copyright © Materials Research Society 1988

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