A novel method to 3D-print fine-grained AlSi10Mg alloy with isotropic properties via inoculation with LaB6 nanoparticles

Metal additive manufacturing offers a tool to bring formerly unmanufacturable, geometrically complex, engineered structures into existence. However, considerable challenges remain in controlling the unique microstructures, defects and properties that are created through this process. For the first time this work demonstrates how LaB6 nanoparticles can be used to control such features in Al alloys produced by Selective Laser Melting (SLM). A novel and efficient mechanical agitation process is used to inoculate AlSi10Mg powder with LaB6 nanoparticles which resulted in a homogenous, crack-free, equiaxed, very fine-grained as built microstructures. The substantial grain refinement is attributed to the good crystallographic atomic matching across the Al/LaB6 interfaces which facilitated Al nucleation on the LaB6 nanoparticles. The LaB6-inoculated AlSi10Mg exhibited near-isotropic mechanical properties with an improved plasticity compared with an modified AlSi10Mg.