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Influence of Gravity Driven Convection on the Directional Solidification of Bi/MnBi Eutectic Composites

Published online by Cambridge University Press:  15 February 2011

Ron G. Pirich  and
D.J. Larson
Ron G. Pirich
Affiliation:
Metals Science Laboratory, Research and Development Center, Grumman Aerospace Corporation, Bethpage, New York, USA
D.J. Larson
Affiliation:
Metals Science Laboratory, Research and Development Center, Grumman Aerospace Corporation, Bethpage, New York, USA
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Abstract

The role of gravity on Bridgman-Stockharger directional solidification of eutectic Bi/MnBi has been studied in reduced gravity aboard NASA sounding rocket SPAR flight experiments and contrasted with normal gravity investigations. The directional solidification of eutectic Ri/MnBi results in a low volume fraction, faceted/nonfaceted aligned rod eutectic whose MnRi rod size, interrod spacing, thermal and magnetic properties are sensitive functions of solidification processing conditions. The morphology of the low-gravity samples showed striking differences compared with identically processed,normal gravity samples grown in the same apparatus. The MnBi rod diameter and interrod spacing distributions were significantly smaller, approximately 50%, for the lowgravity samples compared with identically processed one gravity samples. Accompanying the smaller MnBi rod diameters observed in the flight samples, was an increase in permanent magnet properties which reached greater than 97% of the theoretical maximum.

Gravitationally induced thermal instabilities in one-gravity which result in irregular interface movement and associated difficulty of the faceted MnBi phase to branch are suggested to explain the morphological differences between one and low gravity solidification.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 9 , 1981 , 523
Copyright
Copyright © Materials Research Society 1982

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References

REFERENCES

[1]Tiller, W.A., Liquid Metals and Solidification, (American Society for Metals, 1958), p. 276.Google Scholar
[2]Jackson, K.A. and Hunt, J.D., Tans. AIME 236 (1966), p. 1129.Google Scholar
[3]Mollard, F.R. and Flemings, M.C., Trans. AIME 239 (1967), p 1526.Google Scholar
[4]Tassa, M. and Hunt, J.D., J. Crystal Growth 34 (1976), p. 38.Google Scholar
[5]Fisher, D.J. and Kurz, W., Acta Metallurgica 28 (1980), p. 777.Google Scholar
[6]Boettinger, W. J., Biancaniello, F.S. and Coriell, S.R., Met. Trans. A 12A (1981), p. 321.Google Scholar
[7]Pirich, R.G., Larson, D.J. and Busch, G., AIAA Journal 19 (1981), p. 589.Google Scholar
[8]Pirich, R.G. and Larson, D.J., Grumman Research Department Report RM–602 (1980).Google Scholar
[9]Pirich, R.G., Larson, D.J., Wilcox, W.R. and Fu, T.W., Grumman Research Department Report RM–712 (1980).Google Scholar
[10]Pirich, R.G., Busch, G., Poit, W. and Larson, D.J., Met. Trans. A 11A (1980), p. 193.Google Scholar
[11]McCreight, L.R., Noone, M.J. and Locker, R.J., ESA publication No. 114 (1974).Google Scholar
[12]Pirich, R.G. and Larson, D.J., J. App. Phys. 50 (1979), p. 2425.Google Scholar
[13]Pirich, R.G., Larson, D.J. and Busch, G., IEEE Mag. Trans. MAG–15 (1979), p. 1754.Google Scholar
[14]Pirich, R.G., IEEE Mag. Trans. MAG–16 (1980), p. 1065.Google Scholar
[15]Pirich, R.G. and Adler, P.N., TMS-AIME Mtq, Pittsburg, PA (1980).Google Scholar
[16]Verhoeven, J.D. and Homer, R.H., Met. Trans. 1 (1970), p. 3437.Google Scholar