An Al–Al interpenetrating-phase composite by 3D printing and hot extrusion

We report a process route to fabricate an Al–Al interpenetrating-phase composite by combining the Al–Mg–Mn–Sc–Zr lattice structure and Al₈₄Ni₇Gd₆Co₃ nanostructured structure. The lattice structure was produced by the selective laser melting and subsequently filled with the Al₈₄Ni₇Gd₆Co₃ amorphous powder, and finally the mixture was used for hot extrusion to produce bulk samples. The results show that the composites achieve a high densification and good interface bonding due to the element diffusion and plastic deformation during hot extrusion. The bulk samples show a heterogeneous structure with a combination of honeycomb lattice structure with an average grain size of less than 1 µm and nanostructured area with a high volume fraction of nanometric intermetallics and nanograin α-Al. The heterogeneous structure leads to a bimodal mechanical zone with hard area and soft area giving rise to high strength and acceptable plasticity, where the compressive yield strength and the compressive plasticity can reach ~745 MPa and ~30%, respectively. The high strength can be explained by the rule of mixture, the grain boundary strengthening, and the back stress, while the acceptable plasticity is mainly owing to the confinement effect of the nanostructured area retarding the brittle fracture behavior.