Research on the laser quenching performance of Ti6Al4V-7.3 %Cu alloys fabricated by wire-powder collaborative arc additive manufacturing

In this work, a new arc wire powder synergistic additive manufacturing method was used to prepare Ti6Al4V-7.3 %Cu alloys. This method overcomes the inherent large columnar grain defects in additive manufacturing and the segregation phenomenon of titanium alloys. Three laser quenching processes were also used to surface-treat the Ti6Al4V-7.3 %Cu alloys, and the hardness, microstructure and corrosion properties were studied. The results showed that laser quenching can effectively refine the grains and improve the strength and corrosion resistance. A β to α phase transition occurred, and Ti2Cu was formed. When the β phase is transformed into the α phase, there is an obvious Burgers orientation relationship between the two phases, and the orientation of the α phase in the quenched layer is more concentrated in the build direction (BD). With increasing laser quenching power, the Ti2Cu content in the alloy first increased and then decreased. When the quenching power was 690 W, the performance of the alloy was the best. Compared with those of the as-fabricated sample, the hardness increased by 150 HV, the grain size decreased from 10 µm to 1 µm, and the corrosion potential (Ecorr) increased by 0.195 V. α-Ti + Ti2Cu exhibited better corrosion resistance than β-Ti + Ti2Cu.