Precipitate evolution and thermal stability of A205 fabricated using laser powder bed fusion

The thermal stability of laser power bed fusion A205 was studied via transmission electron microscopy (TEM) following various aging heat treatments. The effects of direct aging at 160 °C and 205 °C were compared with solutionizing and aging. The aging response was evaluated at three different temperatures (170 °C, 190 °C, 205 °C) up to 100 h. Solutionizing above solvus of the alloy at 530 °C with water quenching, followed by aging at 205 °C for 11 h, gave the optimum combination of high yield strength (376 MPa) and ductility (10%) at room temperature, which was retained up to 150 °C (yield strength of 314 MPa). Detailed TEM analysis coupled with atom probe tomography was used to reveal 20 × 1 nm 2 clusters enriched in Cu and Ag in the As-printed condition, which evolved after aging as nanoscaled, Ω (Al–Ag–Cu–Mg) (55 × 7 nm 2 ), and θ′ (Al–Cu) (40 × 5 nm 2 ) precipitates, having an orientation relationship with α-Al, which resisted coarsening and were responsible for the thermal stability during aging up to 200 °C after aging for 100 h. Graphical abstract