Influence of boriding post-treated TiB whiskers on the growth of α-grains in laser-melted Ti-6Al-4V coatings

•Post-borization treatment induces changes in the microstructure of laser-cladding TC4 coatings.•Pinning effect from TiB whiskers elongates the growth of α-sheet layer.•Boronization post-treatment is effective in increasing the microhardness of coating interior and surface. To compensate for the problem of coarse-grained α-slats and low hardness of TC4 coatings that are easily produced by the large cooling gradient formed by laser cladding. A boron process was utilized to post-treat the laser cladding TC4 coatings. It was found that the α content within the coating increased with increasing boriding time. Meanwhile, the pinning effect produced by the TiB whiskers on the coating surface effectively reduced the thickness and increased the length of the α-slats. The grains around the TiB at the top of the coating were significantly refined. The hardness of the coating interior and surface also increased with the increase of holding time. The top hardness reached up to 1256.7 Hv.