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Microstructure of nitrate polycrystals solidified under ultrasonic vibration

Published online by Cambridge University Press:  31 January 2011

Naoya Enomoto
Affiliation:
Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226, Japan
Yasushi Iimura
Affiliation:
Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226, Japan
Zenbe-e Nakagawa
Affiliation:
Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226, Japan
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Abstract

Molten nitrates in the system (1 − x)NaNO3xBa(NO3)2 were solidified in the presence of a power ultrasound of 20 kHz. Their microstructures were compared with those of controlled samples which were solidified normally. Grain size in the controlled sample of monolithic NaNO3 (x = 0) was reduced by sonication. In the hypo- (x = 8 wt. %) and the hypereutectic (x = 28 wt. %) binary samples, the sonication completely eliminated the dendritic structure of the primary crystals and induced equiaxed particles of the primary phase. At eutectic (x = 18 wt. %), the sonication removed oriented structures of the eutectic lamellae. Several mechanisms of the microstructural modification were mentioned.

Type
Articles
Copyright
Copyright © Materials Research Society 1997

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