Additive manufacturing of metal micro-fiber reinforced polymer composites: Processing, mechanical properties, and laminate behavior

• Novel Al/PETG mFRP composites by Fused Filament Fabrication show enhanced stiffness and wear resistance. • MAM produces metal particulate with unique morphologies and surface texture which are anticipated to influence interfacial adhesion. • CLT accurately predicts mFRP elastic response for tailored laminate configurations. • Outer layer orientation controls flexural failure in the laminated mFRPs. A new class of fiber reinforced thermoplastic composites is investigated. Micro-scale metal alloy fibers produced by modulation-assisted machining (MAM) are added to a PETG (Polyethylene Terephthalate Glycol) polymer matrix by direct extrusion. The MAM micro-fibers have unique characteristics – including shape (morphology), size, surface texture and microstructure. The integration of MAM and additive manufacturing (AM) enables a processing route for new structure, property, and performance sets in thermoplastic composites. The composite filament produced by polymer extrusion enables 3D printing of laminate samples by fused filament fabrication (FFF) for evaluation of material properties. The micro-fibers showed a propensity to align in the printing path direction. In uniaxial tension, the laminate strength depends on the orientation of individual printed layers and the bending performance is determined by the outer-most layer orientation (tensile layer). The tensile fracture surface morphologies are compared, and the laminates showed ductile and brittle fractures depending on the layer orientation. Classical laminate theory (CLT) was found to adequately characterize the elastic response. Development of these MAM and AM inspired metal micro-fiber reinforced polymer (mFRP) composites will enable opportunities for tailored material solutions in product designs across a range of applications, including light-weighting in the automotive sector, structural composites for biomedical applications, and high-performance polymers for extreme environments.