Analysis of the growth morphology of TiB and the microstructure refinement of the coatings fabricated on Ti-6Al-4V by laser boronizing

Coatings mainly containing the stick TiB strengthening phase have been fabricated on a Ti-6Al-4V alloy by laser boronizing. Results show that the coating microstructure is refined by the addition of boron. The growth model of stick TiB is mainly attributed to the lattice characteristics of TiB, and the mechanism of the microstructure refinement is attributed to the pre-eutectic TiB crystal embryos acting as heterogeneous nuclei and the growth obstruction of the formed crystals caused by TiB during the solidification.