Achieving high strength in selective laser melting AlSi10Mg alloy by adding microsized pure Cu particles

In this work, a high-strength Al–Cu–Mg–Si alloy was prepared by a selective laser melting (SLM) process with blended powders consisting of AlSi10Mg and microsized pure Cu powders. The influence of Cu addition on the microstructure and mechanical properties of AlSi10Mg alloy has been systematically investigated. The Al–Cu–Mg–Si alloy has a hardness of 173 HV, an ultimate tensile strength of 732 MPa, and a yield strength of 389 MPa, reaching the level of high-strength aluminum alloys. Such increase in the strength and hardness can be attributed to the refinement of eutectic network, enhanced solid solution strengthening and elimination of fracture-prone heat affected zone (HAZ). In addition, the formation of the GP zone caused by adding Cu promotes the precipitation of Si particles within the eutectic network, and Si particles, as the non-shear deformed second-phase, can significantly increase the Orowan strengthening effect. After aging at 180 °C for 2 h, the hardness and yield strength of the alloy are increased to 183 HV and 522 MPa respectively. The presence of the θ′-Al2Cu phase and the high-density of Si particles after 2 h of peak aging further increases the strength and hardness of the alloy.