Microstructure and mechanical properties of an in-situ TiB 2 particle reinforced AlSi10Mg composite additive manufactured by selective electron beam melting

Selective electron beam melting (SEBM) has been recently employed for additive manufacturing (AM) Al alloys but showing comparatively low hardness and strength. In this work, SEBM technique was employed to additive manufacture an in-situ TiB 2 particle reinforced AlSi10Mg composite. With optimized processing parameters, the SEBM TiB 2 /AlSi10Mg composite showed good surface quality and a high relative density. The as-printed composite exhibited a refined equiaxed grain structure with an average size of 27.7 µm. The eutectic Si phase was mostly spherical and uniformly distributed in the Al matrix, while the nano-sized TiB 2 particles were partly agglomerated. The resultant microstructure was associated with the combined effect of the rapid solidification and annealing-like process during SEBM. Additionally, TiB 2 particles facilitated grain refinement by enhancing the heterogeneous nucleation and retarding grain growth. The SEBM TiB 2 /AlSi10Mg composite presented a yield strength (YS) and ultimate tensile strength (UTS) of 103.6 MPa and 165.4 MPa, respectively, with an appreciable elongation of 15% at as-printed state. After a T6-like treatment, the YS and UTS of the composite were further improved to 225 MPa and 316 MPa, respectively, and an elongation of 12% was maintained. This paper shows the potency of SEBM in AM metal matrix composites (MMCs) with both agreeable strength and ductility. Graphical abstract