Article ID: TETSU-2024-147
Reduced Multicomponent Calcium Ferrite was analyzed using STEM-EDS(scanning transmission electron microscope - energy dispersive spectrometer) and 3DAP(three-dimensional atom probe) in order to clarify the reducibility of SFCA(silico-ferrites of calcium and aluminum) based on the microstructure analysis. The morphological observation and crystal structure analysis using STEM-EDS revealed that the amorphous Ca-Si-O oxides, spinel phase (Fe,Mg)(Fe,Al)2O4 and brownmillerite phase (Ca,Fe)2(Fe,Al)2O5 were formed in the metallic iron obtained by the reduction of SFCA. Since the relatively reducible spinel phase was observed after reduction, it is suggested that the formation of spinel phase (Fe,Mg)(Fe,Al)2O4 by the dissolution of Mg into spinel phase affect the reducibility of SFCA. It was also found that each oxide was dispersed in metallic iron in granular form, either singly or in complex form. The three-dimensional analysis by performing 3DAP clarified that the presence of the Fe-O enriched region with a width of about 2 nm existed at the interface between amorphous Ca-Si-O oxide and metallic iron. This result suggests that the morphology of amorphous Ca-Si-O oxides affect the reducibility of SFCA.
