Synthesizing Ti–Ni Alloy Composite Coating on Ti–6Al–4V Surface from Laser Surface Modification

In this work, a Ni-alloy Deloro-22 was laser-deposited on a Ti–6Al–4V bar substrate with multiple sets of laser processing parameters. The purpose was to apply laser surface modification to synthesize different combinations of ductile TiNi and hard Ti2Ni intermetallic phases on the surface of Ti–6Al–4V in order to obtain adjustable surface properties. Scanning electron microscopy, energy dispersion spectroscopy, and X-ray diffraction were applied to reveal the deposited surface microstructure and phase. The effect of processing parameters on the resultant compositions of TiNi and Ti2Ni was discussed. The hardness of the deposition was evaluated, and comparisons with the Ti–6Al–4V bulk part were carried out. They showed a significant improvement in surface hardness on Ti–6Al–4V alloys after laser processing, and the hardness could be flexibly adjusted by using this laser-assisted surface modification technique.