Static and dynamic precipitation phenomena in laser powder bed-fused Ti6Al4V alloy

The present paper investigates static and dynamic precipitation phenomena in the Ti6Al4V alloy produced via laser-powder bed fusion, solubilized at 1050 °C and aged in the range of 450–650 °C. In relation to the distance from the platform on which the samples are disposed during the solution heat treatment, the microstructure varies from α-laths to α-colonies arranged in a Widmanstätten structure. The aging heat treatment at 450 °C promotes the formation of stacking faults into α-laths and the precipitation of α2-Ti3Al phases. SEM and TEM observations reveal that the density of precipitates increases after aging at 500 °C, while coarsening of the α-phase occurs only after aging heat treatment at 600 °C. Vickers microhardness measurements reveal different peak-aging conditions and show that the alloy is unstable at high temperatures (T > 450 °C), both in the case of static and dynamic precipitation phenomena. Only the aging profile at 450 °C shows a constant trend of Vickers microhardness after 4 h of treatment.