A new class of high-performance metal-fiber thermoplastic composites for additive manufacturing

We demonstrate a new class of thermoplastic composites processed by additive manufacturing that utilize aluminum alloy fibers in a Polyethylene Terephthalate Glycol (PETG) matrix. Al6061-T6 microfibers, ~30μm cross section and 0.5 mm length, are merged with a PETG matrix by filament extrusion, and then 3D printed by fused deposition modeling (FDM). The metal fibers are produced by Modulation-Assisted Machining, wherein a low-frequency, sinusoidal oscillation is continuously superimposed onto a cutting process. The discrete fibers produced by the cutting have distinct characteristics, including uniform morphology (shape), roughened surface texture, and fine-grained microstructure, compared to conventional fiber processing. A range of particulate/fiber morphologies can be produced from virtually any metal or alloy, enabling the high-performance metal-fiber composites for additive manufacturing. The mechanical properties of the aluminum fiber/PETG composite show important advantages over other commercially available composites. Fiber-matrix combinations are discussed, along with performance benefits and applications.