Metal-based additive manufacturing (AM) is among the most heavily pursued advanced manufacturing technologies worldwide. Reliable data that capture the transient microstructural transformations during an AM build remain scarce, mainly due to challenges associated with rapid nonequilibrium phase transformations at extreme cooling and heating rates (up to 106 K/s) and repeated thermal cycling in a layer-by-layer fabrication.  We are working to measure these repeated transformations and the resulting complex microstructure using a combination of methods, including nanocalorimetry (a high rate thermal measurement), thermography (surface thermal imaging), electron microscopy (TEM and SEM), and synchrotron-based X-ray scattering and diffraction analysis to provide direct and quantifiable insights into the phase transitions under realistic thermal cycling conditions. Such understanding will connect AM build conditions with the structure and properties of AM materials.  We are interested in advances for AM aluminum alloys, which are of great commercial interest.  

AM alloy development requires an understanding of the material's response to extreme processing conditions. Common in situ monitoring techniques such as thermographic cameras measure surface temperature during AM processing but do not provide thermodynamic and phase-transition data essential to develop a processing-structure-property relationship. Nanocalorimetry quantifies the amount of thermal energy transferred in a chemical or physical process at rapid heating and cooling rates that are fully compatible with aluminum AM processing. Nanocalorimetry can also report on the energetics and kinetics of nucleation, the first step in most crystallization processes but challenging to monitor using other techniques, making it particularly relevant to AM alloys that rely on nucleants to control solidification structure.   

This opportunity would involve working with a team of NIST researchers from the Material Measurement Laboratory (MML) and the Engineering Laboratory (EL) at NIST.

key words

Additive Manufacturing; AM; Materials Science; Metallurgy; Thermal Analysis; Nanocalorimeter; Nanocalorimetry; X-ray; XRD; Electron microscope; Electron microscopy; Synchrotron; Beamline;

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral applicants