Effects of TiB₂ additions on microstructure and mechnical properties of Al–Mg–Sc alloy fabricated by selective laser melting

In this paper, the effect of TB₂ additions on a noval Al–Mg–Sc alloy was studied, and the microstructure and mechanical properties of SLM-fabricated TiB₂/Al–Mg–Sc alloys were investigated. The results showed that molten pool width increased and molten pool depth slightly decreased with TiB₂ increase, due to the laser absorptivity of the TiB₂/Al–Mg–Sc alloys higher than that of Al–Mg–Sc alloy under the same process parameters. The microstructure of SLM-fabricated TiB₂Al–Mg–Sc alloys were composed of fine-grained, coarse-grained and columnar-grained regions, and the fine-grained region increased with the increase of TiB₂ content. The recrystallization regions in SLM-fabricated TiB₂/Al–Mg–Sc alloy decreased with the increase of TiB₂ content, and TiB₂ additions used as heterogeneous nucleation to refine grains, which can pin grain boundaries and prevent recrystallization during SLM process. TiB₂/Al–Mg–Sc alloy with 1% TiB₂ additions showed a relatively higher comprehensive mechanical properties, and the tensile strength is 483 MPa, the elongation is 15.8%. Tensile strength of 1%TiB₂/Al–Mg–Sc alloy was increased by 37 MPa and the elongation is also increased by 2.1% compared with 0%TiB₂/Al–Mg–Sc alloy, and 2%TiB₂/Al–Mg–Sc alloy shown a relatively lower comprehensive mechanical properties due to its lower density and TB₂ agglomerated.