Effect of Post-Build Annealing on the Microstructure and Mechanical Properties of LPBF-Processed AlSn10Pb10 Alloy

The work studied the effect of high-temperature annealing on the phase composition, microstructure, and mechanical properties of an AlSn10Pb10 vol.% alloy obtained by laser powder bed fusion (LPBF). For this purpose, a series of anneals was carried out in the temperature range of 200–500 °C with a duration of 30 min. Using X-ray diffraction, it was determined that the annealed samples had a three-phase structure consisting of Al, β-Sn, and α-Pb phases, with a gradual decrease in their lattice elastic strain and dislocation density as the heating temperature increased. Analysis of the obtained SEM images revealed that these changes were accompanied by the coarsening of Sn and Pb inclusions and growth of the pure aluminum areas. As a result of the described structural changes with increasing annealing temperature, the ultimate compressive strength of the alloy monotonically decreased from 108 MPa (in the as-built state) to 75 MPa after annealing at 500 °C. The alloy’s ductility (strain at peak stress) also improved and reached a maximum of 26% after annealing at 400 °C. Compression test results showed that the optimal combination of ductility and strength of the LPBF-processed AlSn10Pb10 alloy was observed after annealing at 400 °C.