Lattice relations and solidification of the complex regular eutectic (Cr,Fe)-(Cr,Fe)23C6

The eutectic (Cr,Fe)-(Cr,Fe)₂₃C₆ showed a triaxial fishbone structure and could be categorized as a “complex regular structure”. In this study, the lattice relations of the fishbone (Cr,Fe)₂₃C₆ were examined and the solidification process was observed using a transmission electron microscope and a confocal laser scanning microscope. For one of the three fish bones in a eutectic cell, parallel (Cr,Fe)₂₃C₆ lamellas at one side of the spine had the same lattice direction, as did those in the (Cr,Fe) phase. The lattices of neighboring (Cr,Fe)₂₃C₆ and (Cr,Fe) phases were not coherent. Lamellar (Cr,Fe)₂₃C₆ on opposite sides of a spine had different lattice directions, and their lattice boundary was in the spine. By using the confocal laser scanning microscope, the solidification of lamellar eutectic structure could be observed. At the low cooling rate of 5 o C·min^-1, parallel lamellas would grow thick blocks instead of thin plates. To obtain a thin lamellar eutectic structure, the cooling rate should be higher, like the rate in welding.