Science & Technology Thrust (STT) 2: Material Design, Processing, and Characterization for Laser-Based Metal 3-D Printing

STT2 Challenges

An incomplete understanding of:

  • Laser interaction with the powder feedstock.
  • Dynamics of laser-induced melting and melt coalescence.
  • Microstructure evolution during re-solidification including grain growth.
  • Possible segregation of impurities and alloying elements to grain boundaries and boundaries between successively melted and re-solidified regions.
  • Residual stresses and post-printing heat treatment.

Three Focus Areas

1. Powder Synthesis

2. Selective Laser Melting (SLM) 3D Printing

3. Hierarchical Modeling

Powder Synthesis

  • Goal: Understand the influence of relevant thermophysical properties of metallic liquids on custom powder synthesis and SLM printing processes.
  • Objectives:
    • Acquire powder synthesis capabilities.
    • Study the powder synthesis process.
    • Investigate thermophysical properties of metallic liquids.
    • Investigate the influence of powder and liquid characteristics on 3D printing parameters.

Thermophysical Property Measurements (Electrostatic Levitation: ESL)

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Powder Synthesis

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powder

Selective Laser Melting (SLM) 3D Printing

Setup and Commissioning of SLM Instrumentation

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Dross Formation Mechanisms and Impact for Selective Laser Melting

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Porosity Imaging with Spatially Resolved Small Angle Neutron Scattering

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Defect Analysis of Selective Laser Melted Parts by Positron Annihilation Spectroscopy

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Radiation Heat Transfer in Powder Bed

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Demonstration Activities

High Entropy Alloy Development: Experimental Testing and CALPHAD Simulation

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Dr. Yang's Group at Southern Univeristy

In particular, the bulk modulus is calculated along with the Bader charge of each composing element, and charge density contours were calculated to show electron density surrounding certain atoms within the HEA, to investigate the nature of the bonding taking place during the alloy’s formation.

Besides major metallic bonding in the bulk alloy, weak partial covalence bonding are found at Mo-Nb, Nb-Ta, Nb-V, Ta-V and Mo-Nb interatomic bonding.

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Louisiana State University Senior Design Project: A Novel Powder Feeder for Selective Laser Melting Based 3D Printers

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Dr. Shengmin Guo's Group (Louisiana State University) and Dr. Zhao's Group (Southern University): Electromagnetic Interference Shielding Effectiveness of HEAs

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