Microstructure evolution in laser solid forming of Ti-50 wt% Ni alloy

Ti-50 wt% Ni alloys were fabricated by laser solid forming (LSF) using pure Ti and Ni powders. Effects of laser process parameters (laser power and scanning speed) on the deposited microstructures were investigated. With increasing scanning velocity and decreasing laser power, as-deposited microstructure exhibited an evolution from primary TiNi dendrite to two-phase TiNi + B2 dendrite and finally to TiNi + Ti₂Ni anomalous eutectic, meantime, the characteristic size of the dendritic arms also decreased. The experimental results were further compared with the model of Trivedi, Magnin, Kurz (TMK model) of eutectic growth and Kurz, Giovanola, Trivedi (KGT model) of dendrite growth. The experimental results are in a reasonable agreement with KGT model.