CONTROL OF A SEGREGATION DURING DIRECTIONAL SOLIDIFICATION OF THE MANGANESE-ZINC FERRITE

The composition of the ZnFe2O4 - MnFe2O4 ferrite has been determined o n 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 metho d of the directional solidification. The open Bridgman system with oxy gen atmosphere of a proper pressure, a positive temperature gradient, constant growth rate and continuous addition of an alloy of the nomina l concentration has been applied. The chemical segregation along the l ongitudinal axis of obtained single crystal has been examined by means of scanning electron microscopy. The possibly small distances between analysed areas has been applied. Some obtained results of measurement s have been compared with those of calculations. The improvedBrody - F lemings' theory worked out for linear and parabolic movement of the lo cal s/l interface has been used for the calculations. The obtained mic rographs have allowed to control considered segregation via theoretica l prediction and decrease an inhomogeneity. For that reason three feat ures of both theoretical and experimental curves have been differentia ted and analysed.