Dataset for paper entitled, 'Isomorphic grain inoculation in Ti-6Al-4V during additive manufacturing'. Abstract: The potential for using isomorphic inoculation (ISI) to grain refine titanium alloys in additive manufacturing was investigated by adding TiAlNb particles to Ti-64 during building test samples. A surviving particle was identified and its crystallographic relationship with the matrix studied by transmission Kikuchi diffraction. The particle and bulk matrix grain were shown to have the same crystallographic orientation, demonstrating that the ISI mechanism of solidification bypasses the nucleation step in favour of direct epitaxial growth. Paper doi: https://doi.org/10.1016/j.mlblux.2020.100057