Development of freeform fabrication method for Ti–Al–Ni intermetallics

A new droplet-based reactive rapid prototyping (RRP) method for making intermetallic parts is demonstrated. This method combines the processes of solid freeform fabrication (SFF) and combustion synthesis (CS). Intermetallic beads are produced by the CS reaction. These synthesized beads are assembled and joined by using the SFF technique with the aid of heat released from exothermic reactions. The intermetallic compound of Ti–Al–Ni is chosen to demonstrate this method. Ni was added to the Ti–Al system to enhance the reaction. Thermodynamics of the Ti–Al–X·NI (X=5, 10, 15 wt.%) system are calculated. The effects of the addition of Ni in powder bed and heating temperature of aluminum droplets on the width and thickness of the reacted area were investigated. As an example, a Ti–Al–Ni intermetallic bar with simple shape was fabricated as a demonstration of RRP.