Hierarchical microstructure and strengthening phenomena in additively manufactured aluminum alloysTuesday (05.11.2019) 17:35 - 17:55 Part of:
Laser additive manufacturing (AM) techniques have gained tremendous attention recently due to distinctive characteristics they introduced to metal fabrication and processing. Of particular interest is the selective laser melted AlSi10Mg alloys, which have applications in aerospace, automotive, and marine industries. Using multi-scale advanced electron microscopy techniques, an ultrafine microstructure was identified for such alloys involving dislocation networks, nanoscale Si precipitates, cell walls and boundaries, grain structures, and melt pools. This unique microstructure led to exceptional mechanical properties under quasi-static, elevated, and high strain rate dynamic loading conditions obtained using common mechanical testing procedures including a split Hopkinson pressure bar. A hardening law accounting for strengthening due to interactions with forest dislocations as well as with dislocation cells was proposed using the backstress concept. the model was calibrated against experimentally measured microstructural features during deformation. The inhomogeneous distribution of slip arising from microstructural features, evolving cells, and effective obstacle strength was discussed.