J. Phys. IV France 07 (1997) C1-77-C1-78
Control of a Segregation during Directional Solidification of the Manganese-Zinc FerriteW. Wolczynski1, E. Guzik2, R. Ciach1 and J. Kloch3
1 Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 30 059 Krakow, Reymonta 25, Poland
2 Faculty of Foundry, University of Mining and Metallurgy, 30 059 Krakow, Reymonta 23, Poland
3 Institute of Mathematics, Polish Academy of Sciences, 31 027 Krakow, Sw. Tomasza 30, Poland
The composition of the ZnFe2O4 - MnFe2O4 ferrite has been determined on the basis of pseudobinary phase diagram calculated on the assumption that chemical potential of both components are equal for both liquid and solid solutions. A single crystal has been produced applying method of the directional solidification. The open Bridgman system with oxygen atmosphere of a proper pressure, a positive temperature gradient, constant growth rate and continuous addition of an alloy of the nominal concentration has been applied. The chemical segregation dong the longitudinal axis of obtained single cristal has been examined by means of scanning electron microscopy. The possibly small distances between analysed areas has been applied. Some obtained results of measurements have been compared with those of calculations. The improved Brody - Flemings' theory worked out for linear and parabolic movement of the local s/l interface has been used for the calculations. The obtained micrographs have allowed to control considered segregation via theoretical prediction and decrease an inhomogeneity. For that reason three features of both theoretical and experimental curves have been differentiated and analysed.
© EDP Sciences 1997