Search

ABSTRACTSelective laser melted (SLMed) AlSi10Mg alloys usually fail before necking during tensile tests, which results in inadequate ductility. To overcome this problem, here we introduced Al4C3 nanorods into the primary Al cells of SLMed AlSi10Mg via in-situ chemical reaction. Tensile tests revealed that those in-cell Al4C3 nanorods not only increased the strain-hardening ability of SLMed AlSi10Mg but also delayed the fracture beyond necking. Consequently, 15% of tensile strength increase and 78% of ductility increase were achieved simultaneously. Post-tensile TEM analysis revealed that those in-cell Al4C3 nanorods pinned and accumulated dislocations within cells and thus alleviated stress concentration along cell boundaries.

Laser powder bed fused (LPBFed) AlSi10Mg is recognised for its superior mechanical properties. However, its thermal stability has never been justified. Herein, we exposed as-built AlSi10Mg to different temperatures (200–500°C) for only 3 min to evaluate its thermal stability. Results showed that LPBFed AlSi10Mg had relatively low thermal stability. Only 3 min of thermal exposure at 200°C would deteriorate its tensile strength dramatically. Microstructural analysis revealed that with increasing thermal input, as-built AlSi10Mg exhibited a microstructural evolution similar to annealing of cold-worked metals, namely recovery, recrystallisation followed by grain-growth. The excessive energy stored in as-built microstructure due to fast cooling during LPBF was deduced as the driving force for this phenomenon. Therefore, such microstructural change was at the expense of dislocations stored in the as-built material, which in turn caused deterioration in tensile strength. The present findings may provide guidance for the application of LPBFed AlSi10Mg.