Selective laser melting of a novel Al-Si-Fe-Mn-Ni alloy with superior mechanical properties at both room and elevated temperatures: Influence of processing parameters and heat treatment

In this study, a novel heat-resistant Al-Si-Fe-Mn-Ni alloy suitable for selective laser melting technique was developed. By optimizing the process parameters, as-built alloy with few defects and superior mechanical properties was manufactured at a laser power of 350 W and a scanning speed of 1300 mm/s, with horizontal and vertical ultimate tensile strengths of 589 and 529 MPa, respectively. Conventional annealing, solid solution and T6 treatments were conducted to investigate the effect of post heat treatments on the microstructure and mechanical properties. Owing to the low diffusion capacity of Fe, Mn and Ni elements, the alloys show excellent high-temperature stability. The initial eutectic structure is retained after annealing, with few changes in the morphology of the precipitated phases. During solution treatment, the Al-Si eutectic breaks up to form diffusely distributed Si particles, and Fe, Mn-rich intermetallic compounds as well as AlFeNi phases gradually precipitate out, which further occurs in T6 state. Due to its high-temperature resistance, the alloy developed in this study exhibits better high-temperature mechanical properties than conventional commercial AlSi10Mg alloys, showing higher strength in high-temperature tensile experiments from 150 degrees C to 300 degrees C.