Strengthening mechanisms in direct metal laser sintered AlSi10Mg: Comparison between virgin and recycled powders


Rod shaped samples of AlSi10Mg additively manufactured using recycled powder through direct metal laser sintering (DMLS) process showed higher quasi-static uniaxial tensile strength in both horizontal and vertical build directions than those of cast counterpart alloy. In addition, they offered mechanical properties within the range of other additively manufactured counterparts. TEM showed that the microstructure of the as-built samples comprised of cell-like structures featured by dislocation networks and Si precipitates. HRTEM studies revealed the semi-coherency characteristics of the Si precipitates. After deformation, the dislocation density increased as a result of generation of new dislocations due to dislocation motion. The dislocations bypassed the precipitates by bowing around them and penetrating the semi-coherent precipitates. Strengthening of recycled DMLS-AlSi10Mg alloys manufactured in both directions was attributed to Orowan mechanism (due to existence of Si precipitates), Hall-Petch effect (due to eutectic cell walls), and dislocation hardening (due to pre-existing dislocation networks). Due to the slightly different microstructure, the contribution of each strengthening mechanism was slightly different in identical samples made with virgin powder.

Publication Title

Additive Manufacturing