Effect of the lattice structure on the interface zone and the final properties of novel PrintCast Ti64-AlSi9Cu3 interpenetrating phase composites

It is an ongoing challenge, especially in metals, to simultaneously improve the strength and energy absorption capacities while remaining lightweight, since these properties have frequently conflicted with each other. Here, we present a topology design approach to address this issue by developing novel metal-metal interpenetrating phase composite systems (IPCs) by infiltrating an AlSi9Cu3 melt into three-dimensionally additively manufactured Ti64 strut-based lattice structures (Cubic and BCCZ). Our key interest lies in forming an interface zone between the lattice structure and the matrix, which can play a critical role in determining the final properties of the IPCs. The results demonstrated that both the AM-Ti64 lattices and AlSi9Cu3 matrix have continuously bonded by the formation of an interface zone to form solid metal-metal IPC systems. Changing the design of the lattice structure from Cubic to BCCZ reduced the Al matrix-casting pores and defects due to the increased surface area fraction. Furthermore, both IPC systems exhibit superior mechanical performance compared with the rule-of-mixtures prediction and compared with each material separately, most likely due to the continuous interface zone that firmly bound the materials. Through a comparative analysis of our IPCs with published literature on metal-metal IPCs, we demonstrated the superior combination of compressive strength and lightweight characteristics exhibited by our IPC systems. This study sheds light on how the lattice structure architecture can tailor the final properties and the interface zone composition of the Ti64-AlSi9Cu3 IPC systems. Our results establish important groundwork for widespread research efforts on IPC systems with unprecedented mechanical and physical properties.