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Microstructural Evolution and Densification Kinetics During Sintering of Oxide-Dispersed Tungsten Alloys

Published online by Cambridge University Press:  25 February 2011

Li-Chyong Chen  and
Bernard P. Bewlay
Li-Chyong Chen
Affiliation:
GE Corporate Research and Development, Schenectady, NY 12301.
Bernard P. Bewlay
Affiliation:
GE Corporate Research and Development, Schenectady, NY 12301.
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Abstract

The present paper discusses the role of ceria and hafnia dispersions in tungsten alloys on the microstructural evolution and densification kinetics during sintering. Densification kinetics were measured using dilatometry, and microstructural changes were examined using scanning electron microscopy and Auger electron spectroscopy. Activation energies for sintering were obtained by analyzing the shift of the iso-density points as a function of linear heating rate. Sintering of both tungsten and ceria-dispersed tungsten were found to be controlled by grain boundary diffusion, with apparent activation energies of 318±21 and 385±15 kJ/mole, respectively. However, densification of hafnia-dispersed tungsten is not controlled by a single mechanism. Under different conditions hafnia can enhance or retard densification; the mechanisms associated with this behavior are discussed. In particular, the relationships between sintering behavior and the tungsten-ceria and tungsten-hafnia interfaces are examined. Comparison with conventional oxide dispersoids, such as thoria, will also be made.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 322: Symposium F – High-Temperature Silicides and Refractory Alloys , 1993 , 483
Copyright
Copyright © Materials Research Society 1994

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