Laser powder bed fusion of nano-titania modified AlSi10Mg alloy: Mechanical properties and strengthening mechanisms

The application of laser powder bed fusion (LPBF) prepared Al matrix alloy is usually hindered by severe coarse column grains and insufficient mechanical properties. This work introduced nano-TiO2 particles as a novel grain refiner and reinforced phase to control such phenomena in the LPBF-fabricated (LPBF-ed) AlSi10Mg alloy. The addition of TiO2 was optimized to achieve the reinforcement of AlSi10Mg alloy. Results show that adding nanoTiO2 particles can decrease the average grain size and consequently eliminate the pores in nano-TiO2/AlSi10Mg alloy, and the combination of in-situ formed L12-Al3Ti, TiO2 nanoparticles and Al matrix is quite tight. The LPBFed TiO2/AlSi10Mg alloy has demonstrated a remarkable improvement in mechanical properties, with a tensile strength of 482 MPa and ductility of 14 %, surpassing most previously reported LPBF-ed AlSi10Mg with the addition of second phases. The cooperative effects of pores elimination, grain refinement, pinning effect, and precipitation strengthening of nanophase are considered to be responsible for their excellent mechanical properties, making the LPBF-ed TiO2/AlSi10Mg alloy a potential standout in its application field.