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Ductile-Phase Toughening in Niobium-Niobium Silicide Powder Processed Composites

Published online by Cambridge University Press:  21 February 2011

Rama M. Nekkanti  and
Dennis M. Dimiduk
Rama M. Nekkanti
Affiliation:
NRC Fellow
Dennis M. Dimiduk
Affiliation:
Wright Research and Development Center, WRDC/MLLM, Wright-Patterson AFB, OH 45433
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Abstract

The Nb-Si system offers a possibility of ductile-phase toughening of the brittle Nb5Si3 intermetallic with the terminal niobium-silicon solid solution. Powder composites have been made in which the volume fraction of the terminal Nb-Si phase is systematically varied in a matrix of Nb5Si3 in order to study the extent of toughening. The Nb-Si solid-solution phase was observed to exhibit cleavage failure under both as hot pressed and heat treated conditions, thereby limiting the toughening attained by the presence of this phase. Hot working of the composite results in a dramatic improvement in toughness because of a change in the plastic behavior and fracture mode of the terminal Nb-Si phase from brittle cleavage to a mixed mode of cleavage and ductile microvoid growth and coalescence (dimpled) fracture.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 194: Symposium R – Intermetallic Matrix Composites I , 1990 , 175
Copyright
Copyright © Materials Research Society 1990

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