Research Technology Master Calendar

Abstract: Additive manufacturing (AM) is traditionally viewed as a complex geometric shaping tool. In this talk, I will present a paradigm shift, using AM as a dynamic platform for in-situ architecturing of 3D microstructural composites, enabling programmable control over material microstructures to overcome long-standing property trade-offs. My research group focuses on creating such architectured composites across different AM modalities, from laser-based metal printing to extrusion-based polymer composite fabrication.

First, in laser powder bed fusion (L-PBF) of metal matrix composites (MMCs), by exploiting the rapid thermal cycles during laser melting/solidification, we achieved in-situ growth of high-quality continue graphene layers within a metal matrix. This enables direct printing of carbon nano-reinforcement structures that are architectured in 3D inside the bulk metal. The resulting continuous graphene network delivers a 72% increase in ultimate tensile strength (648 MPa) in a Ni-based composite while retaining 54% maximum elongation.

Second, we designed and fabricated heterostructured alloys via L-PBF, creating architectured dual-phase composites (e.g., in CuCrZr alloy) where hard, conductive printed regions and soft, ductile powder-derived regions coexist. This heterostructure yields an unprecedented combination of high strength (669 MPa), good ductility (20.6%), and high electrical conductivity (82.7% IACS) in a Cu alloy, showing that programmable architectural design can resolve multi-property conflicts.

Third, shifting from metals to polymer composites, extrusion-based AM techniques (e.g., FDM, inkjet, EHD, DIW) are widely used but suffer from practical issues such as nozzle clogging, shear-induced damage to delicate fillers, and an inherent trade-off between resolution and build rate. To overcome these bottlenecks, we developed an outer-wall flow nozzle configuration that fundamentally reconfigures the nozzle–ink interface to enable clog-free extrusion of highly-filled polymer composite inks.

Bio: Dr. Zhang obtained his M.S. and Ph.D. degrees in Mechanical Engineering from the University of Illinois Urbana Champaign. He earned his Bachelor's degree from Zhejiang University. Before he joined HKUST (GZ), he was a postdoctoral associate working with Prof. John Hart in Mechanical Engineering at MIT. Dr. Zhang's main research interests are metal additive manufacturing and advanced composite materials.

Host: Professor Sam Tawfick