Laser Additive Manufacturing of Metal Matrix Nanocomposites

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Laser additive manufacturing, a layered deposition process in the family of 3D Printing, is of significance to directly produce complex metallic parts. Nanoparticle reinforced metallic materials (i.e. metal matrix nanocomposites) have recently demonstrated great potentials to achieve significantly enhanced mechanical properties. Laser additive manufacturing of metal matrix nanocomposites will thus be promising for widespread applications. However, there are some long-standing challenges limiting the mechanical performance and shape accuracy in laser additive manufacturing of metal parts. This award support fundamental research to provide knowledge needed to break the existing barriers and extend the process capability and application space in aerospace, defense, automotive, and biomedical industries, thus enhancing US competiveness in global advanced manufacturing. Engineering education for both undergraduate and graduate students will be enhanced through curriculum developments and improvements. The project will also attract more historically underrepresented students. K-12 students, teachers, and industries will be exposed to the new technology.The research objective of this project is to understand (1) the accumulative effects of nanoparticles (of various types, loadings, sizes, and shapes) on microstructure, material properties, surface finish/accuracy, and residual stress; and (2) the effects of nanoparticles on laser absorption and thermophysical properties of molten pool and deposited layers in laser additive manufacturing of metal matrix nanocomposites. Single and multiple layers (3~5 layers) of metal matrix nanocomposites with nanoparticles (of various types, loadings, sizes, and shapes) will be laser deposited. Optical and electron microscopies, white light interferometer, X-ray diffraction, and micro/nano-mechanical testing will be used to measure microstructure, surface finish/accuracy, residue stress, and material properties, respectively. Laser absorption during additive manufacturing will be measured by optical power sensor; thermophysical properties of laser-induced molten pool and deposited nanocomposites will be determined experimentally, including specific heat (by differential scanning calorimetry), thermal conductivity (by laser flash method), viscosity of molten pool (by high temperature viscometer), and surface tension of molten pool (by sessile drop experiments).