Layerless Additive Manufacturing of Metal Alloy Lattices Using Immiscible-Interface Assisted Direct Metal Drawing

State-of-the-art metal alloy additive manufacturing (AM) techniques construct a three-dimensional structure through sintering or melting dry metal powders in a layer-by-layer fashion, which typically results in several AM-specific issues in the final structure, such as staircase effect, residual stress and highly-orientated microstructures. In this paper, we present a new extrusion-based metal AM process, named Immiscible-interface assisted Direct Metal Drawing (II-DMD), which fabricates metal alloy structures, in particular lattice structures, in a layerless manner. In the II-DMD process, metal lattice structures are fabricated by continuously extruding a metal colloidal suspension within a second immiscible matrix colloidal suspension. The shape of the metal colloidal suspension is stabilized due to the presence of an immiscible interface between the two colloidal suspension systems. Dense metal lattice structures can be achieved via post-consolidation of the self-stabilized metal-matrix systems, including liquid-phase drying and metal-phase sintering. The II-DMD process is presented and the immiscible-interface-assisted self-stabilization mechanism is studied. The post-consolidation processes are discussed. Several test cases were fabricated and characterized.