Interface structure and chemistry in a novel steel-based composite Fe–TiB2 obtained by eutectic solidification

A new generation of steels, Fe–TiB2 composites, is designed for automotive applications. The product displays both a high stiffness and a low density in comparison with existing steels and is prepared by eutectic solidification directly from the melt. A homogeneous distribution of TiB2 particles is achieved. The structure and chemistry of the internal interfaces will clearly determine the quality of interfacial cohesion during processing and further loading. Here, fundamental investigations at the atomic level are performed by transmission electron microscopy. The preferred interface planes for diboride particles are prismatic {101¯0} planes (in the majority) and the basal plane. No second phase is detected at prismatic planes. Basal type interfaces appear more or less covered by TiC particles, which are also present in the bulk and at iron grain boundaries. The interfacial crystallography and defects are accurately determined. Our results strongly support the good interfacial cohesion assumed for this novel steel-based composite displaying enhanced mechanical behaviour.