The influence of mixing enthalpy on the geometric properties of laser solid formed Ti-6Al-4V

Ti-6Al-4V alloy samples were deposited by laser solid forming from blended 90wt%Ti+6wt%Al+4wt%V powders and from pre-alloyed Ti-6Al-4V powders under the same processing parameters, and the geometric properties of the deposited samples were studied comparatively. It was found that the height and the width of the deposited layers increased with the increase of the laser power and the decrease of the laser scanning velocity. Meanwhile, the height and the width of the deposited layer obtained from blended elemental powders are much higher than that from pre-alloyed powders. The mixing enthalpy for Ti-6Al-4V was calculated by using the Miedema model and the Toop model, and it was found that the alloying process for Ti, Al and V in the molten pool is exothermic, which is responsible for the higher deposited layer height and width of LSF Ti-6Al-4V from blended elemental powders due to the higher energy in the molten pool and the higher temperature of the molten pool.