Control of a Segregation during Directional Solidification of the Manganese-Zinc Ferrite

Abstract
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.