Specific Response of Additively Manufactured AlSi9Cu3Fe Alloy to Precipitation Strengthening

The additive manufacturing of Al–Si–Cu/Mg alloys along with their precipitation strengthening represents a promising option of producing high-strength complex-shaped light-weight components for special applications in automotive or aerospace. In this paper, we follow our previous research on AlSi9Cu3Fe alloy prepared by one of the additive manufacturing technologies, selective laser melting (SLM). We characterize the precipitation strengthening of this material during conventional T6 heat treatment, and also present the possibility of its precipitation strengthening by annealing at temperatures of 413–453 K without previous solutionizing. We revealed the specific response of the studied material consisting in the simultaneous precipitation of semi-coherent θ′ precipitates and Si platelets. By characterization of hardness, mechanical performance under tensile loading and microstructure, we demonstrate that the AlSi9Cu3Fe alloy is not stable when prepared by SLM and its stability can be induced by additional heat treatment. The results of our work thus yield with a practical recommendation for applications where temperature increase may occur.