A laser powder bed fusion system for operando synchrotron x-ray imaging and correlative diagnostic experiments at the Stanford Synchrotron Radiation Lightsource.

Laser powder bed fusion (LPBF) is a highly dynamic multi-physics process used for the additive manufacturing (AM) of metal components. Improving process understanding and validating predictive computational models require high-fidelity diagnostics capable of capturing data in challenging environments. Synchrotron x-ray techniques play a vital role in the validation process as they are the only in situ diagnostic capable of imaging sub-surface melt pool dynamics and microstructure evolution during LPBF-AM.

An instrument for in situ time-resolved X-ray imaging and diffraction of laser powder bed fusion additive manufacturing processes.

In situ X-ray-based measurements of the laser powder bed fusion (LPBF) additive manufacturing process produce unique data for model validation and improved process understanding. Synchrotron X-ray imaging and diffraction provide high resolution, bulk sensitive information with sufficient sampling rates to probe melt pool dynamics as well as phase and microstructure evolution. Here, we describe a laboratory-scale LPBF test bed designed to accommodate diffraction and imaging experiments at a synchrotron X-ray source during LPBF operation.

Nanoscale surface tracking of laser material processing using phase shifting diffraction interferometry.

Phase shifting diffraction interferometry (PSDI) was adapted to provide real-time feedback control of a laser-based chemical vapor deposition (LCVD) process with nanometer scale sensitivity. PSDI measurements of laser heated BK7 and fused silica substrates were used to validate a finite element model that accounts for both refractive index changes and displacement contributions to the material response. Utilizing PSDI and accounting for the kinetics of the modeled thermomechanical response, increased control of the LCVD process was obtained.