Fabrication of TiAl alloy with no multiple heat-affected bands using continuous direct energy deposition

TiAl alloys fabricated through direct energy deposition (DED) are normally characterized by appearance of multiple heat-affected bands, which could jeopardize homogeneity of microstructure. As a kind of DED methods, continuous direct energy deposition (CDED) is similar to directional solidification technique, during which laser beam moves only upwards. Therefore, formation of multiple heat-affected bands may be avoided. In this paper, a Ti-48Al-2Nb-2Cr alloy is prepared using CDED, and a numerical model is developed to simulate thermal history during deposition. Directionally solidified columnar grains with no multiple heat-affected bands is achieved in the deposited alloy. Simulation results reveal that the alloy experiences a continuous cooling with a reduced cooling rate during CDED process.