A downsized laser powder bed fusion device for operando neutron studies: design and experiments

This work reports on the development of a downsized laser powder bed fusion device for operando neutron characterization. The design considerations, device configurations, and detailed setup are described. The device is optimized for installations at neutron diffraction and instruments for diverse studies of the structural and microstructural evolution and constitution of metallic components during printing. In conjunction with introducing the device, we provide examples of operando neutron diffraction for strain analysis and operando neutron imaging for defect characterization and temperature mapping at two different beamlines of the Swiss Spallation Neutron Source. By acquiring diffraction patterns of crack-susceptible materials and tracking the shift of a diffraction peak, the evolution of thermal contributions to elastic strains within a fixed volume can be determined, during processing. Bulk defect characterization is realized by continuously acquiring radiographs during manufacturing. The change in the neutron beam attenuation is correlated with the final microstructure and it confirms the capability of the technique to operando characterize defect formation within the probed bulk. We further demonstrate how using a Beryllium filter and, thus, the long wavelength part of a cold neutron spectrum, allows obtaining spatially and temporally resolved temperature maps during printing of bimetallic composites. • We report on the successful development of a downsized laser powder bed fusion device specifically designed for operando neutron characterization. • Several examples of initial studies utilizing the device with neutron diffraction and imaging are presented and include operando strain analysis, operando defect characterization, and operando temperature mapping. • The potential for other advanced neutron characterization techniques and applications is discussed.