Tunable properties and microstructure net-shape aluminum matrix composites parts fabricated via 3D printing.

M. Seleznev, J. Roy-Mayhew, J. Faust
Markforged Inc.,
United States

Keywords: aluminum matrix composite, 3D printing, tunable properties, tunable microstructure


Aluminum matrix composites (AMCs) are a specific type of metal matrix composite engineered for exceptional properties at low densities (e.g. stiffness, strength at room and elevated temperature, wear resistance, fatigue, thermal conductivity, thermal expansion). Such properties make them prime candidates for advanced applications like precision mechanics, UAVs, rocketry, and semiconductor packaging among others. Despite this, these materials are rarely used, especially in comparison to polymer matrix composites. A main obstacle to AMC market traction is manufacturability. Metal-ceramic materials are impractical to machine and there lacks a flexible and economical technology to manufacture net shape AMCs. The present work shows a novel tool-less technology for manufacturing AMC parts using flexible and economical fused filament fabrication (FFF) 3D printing of ceramic preforms followed by pressure-less infiltration with an aluminum alloy. With FFF printing we are able to combine particulate and continuous fiber reinforcement in a part. Furthermore, by changing printed part’s infill pattern geometry and density we can control not only an overall volume fraction, but also the reinforcement spatial architecture in an AMC part internal volume. AMC strength and stiffness markedly increased with ceramic particulate reinforcement infill density rising from 60 and 100 percent, reaching maximum values of 549 MPa and 149GPa respectively, while fiber reinforced AMCs exhibited 825MPa strength and 142 GPa modulus when using 3-point-bend loading scheme. Particulate reinforcement infill pattern geometry had a clear effect on AMC toughness – switching from orthogonal to gyroid infill pattern at the same infill density resulted in over 50 percent work of fracture increase.