Enhanced mechanical properties by eutectic cells in AlSi10Mg-A promising paradigm for strengthening aluminum in additive manufacturing

AlSi10Mg, as-built by laser powder bed fusion, includes performance-enhancing refined eutectic cells invariably paired with performance-impairing melt pool boundaries, where the cell network coarsens and breaks down. Eliminating melt pool boundaries (and their associated anisotropy) is a motivation for conventional heat treatments but at the cost of removing the AM-specific eutectic cell strengthening. This work evaluates the advantages and disadvantages of retaining the AlSi10Mg cell network (with melt pool boundaries) via direct aging, in contrast to a conventional (T6) approach, which relies primarily upon precipitation strengthening. We compare both heat treatment approaches and their impacts on microstructure, tensile properties, fracture, strainhardening, and thermal stability. Direct aging achieves superior thermal stability and performance by preserving the as-built cell network and its exceptional strain-hardening capacity, despite the retained melt pool boundaries. As-built eutectic cells (which closely depend on build parameters and do not require post-processing) offer unique promise as potential enablers of voxel-by-voxel AM property control.