Laser-based powder bed fusion (LPBF) is one of the most versatile and widespread additive manufacturing techniques for processing metals. Despite decades of research in this very active scientific field, there are still many open questions regarding the relationship between process parameters and microstructural evolution. One successful pathway towards a better understanding of this relationship is the use of in situ techniques. For this purpose, we have developed a miniaturized laser powder bed fusion device that is compatible with synchrotron X-ray diffraction and imaging beamlines. In combination with fast X-ray detectors, this setup allows tracking the evolution of crystallographic phases, local temperature, cracks, pores, etc. during LBPF with time resolutions in the tens of microseconds range.

In this presentation, I will highlight recent developments and results obtained with this setup. In particular, I will demonstrate that operando X-ray diffraction allows tracking the phase evolution and local cooling rates in Ti-alloys, Al-alloys and steel. The outcome of such experiments are directly compared with simulations and/or models. I will also show how fast in situ X-ray radiography provides information on the formation of defects in Ni alloys. Furthermore, when combined with acoustic and optical sensors, these experiments provide the necessary input for machine-learning algorithms.