Formation of bulk titanium boride (TiB) nano‐ceramic with Fe–Mo addition by electric‐field‐activated‐sintering

The present work is focused on optimization of Fe–Mo content, which is essential for transient liquid phase formation and densification, during in‐situ reaction sintering of nanostructured titanium boride (TiB) in the bulk form. The principle objective is to develop a systematic understanding of how the Fe–Mo additions affect the densification, microstructure, and hardness of the TiB nano‐ceramic. Various TiB ceramic compositions, with varying Fe–Mo content and retaining a high‐volume fraction of TiB in the final microstructure, were made by the electric‐field‐activated‐sintering (EFAS) technique. An increase in Fe–Mo content is found to decrease the beginning point of densification temperature/time during the consolidation process through transient liquid phase formation. It is shown that at the optimum level of Fe–Mo, which is around 1.5 wt%, the density and hardness reach maximum levels with a least amount of spatial segregation of Fe within the ceramic. Interestingly, it has been found that Mo is uniformly incorporated within the orthorhombic lattice of the boride, while Fe is largely segregated to β‐Ti phase. At the optimal Fe–Mo content (1.5 wt%), a relative density of 99.7% and a Vickers hardness of 2050 ± 40 kg/mm2 were achieved. From microstructural and X‐ray diffraction analyses, it is found that a high proportion of TiB (>99 vol%), with a least amount of metallic ductile phase, is formed in this composition.