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Grain Boundaries and Interfaces in MoSi2 and MoSi2-SiC Composites and Their Effect on High Temperature Strength

Published online by Cambridge University Press:  02 July 2020

R. Mitra ,
W.-A. Chiou  and
A. Venugopal Rao
R. Mitra
Affiliation:
Department of Materials Science and Engineering, Northwestern University, Evanston, IL60208 Defense Metallurgical Research Laboratory, Hyderabad500 058, INDIA
W.-A. Chiou
Affiliation:
Department of Materials Science and Engineering, Northwestern University, Evanston, IL60208
A. Venugopal Rao
Affiliation:
Defense Metallurgical Research Laboratory, Hyderabad500 058, INDIA
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Extract

Molybdenum di-silicides (MoSi2) based materials have a strong potential for high temperature structural applications due to high melting point of 2030°C, outstanding elevated temperature oxidation resistance and limited ductility above a temperature range of 1100-1300°C. The major shortcomings of MoSi2 for structural applications are its poor room temperature fracture toughness and low high temperature strength. Sustained efforts including reinforcing MoSi2 with ceramic reinforcements, alloying and in-situ processing, have been made to improve these properties. The purity of grain boundaries and interfaces, which in turn depends on the processing method plays a significant role in the high temperature properties and this paper aims to show that.

Intimately mixed Mo and Si powders (Mo:Si = 63:37 by weight fraction) were reaction hot pressed (“RHP“) in vacuum at 1500°C for 1 h, using a pressure of 26 MPa. During the hot pressing process, Mo and Si reacted to form MoSi2.

Type
Ceramics & Minerals
Information
Microscopy and Microanalysis , Volume 6 , Issue S2: Proceedings: Microscopy & Microanalysis 2000, Microscopy Society of America 58th Annual Meeting, Microbeam Analysis Society 34th Annual Meeting, Microscopical Society of Canada/Societe de Microscopie de Canada 27th Annual Meeting, Philadelphia, Pennsylvania August 13-17, 2000 , August 2000 , pp. 424 - 425
Copyright
Copyright © Microscopy Society of America

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References

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2. Mitra, R. et al, Mater. Sci. Eng., A, 225 (1997) 105.CrossRefGoogle Scholar

3. Mitra, R. et al, in Structural Intermetallics 1997, eds. Nathal, N. et al, TMS, Warrendale, PA (1997) 959.Google Scholar

4. The authors acknowledge the encouragement received from Dr. D. Banerjee, Director, DMRL, India and the financial support from DRDO, India. This research made use of Materials Research Center facilities at Northwestern University, supported by NSF under grant # DMR-9632742.Google Scholar