Revealing dynamic processes in laser powder bed fusion with in situ X-ray diffraction at PETRA III

Abstract

The high flux combined with the high energy of the monochromatic synchrotron radiation available at modern synchrotron facilities offers vast possibilities for fundamental research on metal processing technologies. Especially in the case of laser powder bed fusion (LPBF), an additive manufacturing technology for the manufacturing of complex-shaped metallic parts, in situ methods are necessary to understand the highly dynamic thermal, mechanical, and metallurgical processes involved in the creation of the parts. At PETRA III, Deutsches Elektronen-Synchrotron, a customized LPBF system featuring all essential functions of an industrial LPBF system, is used for in situ x-ray diffraction research. Three use cases with different experimental setups and research questions are presented to demonstrate research opportunities. First, the influence of substrate pre-heating and a complex scan pattern on the strain and internal stress progression during the manufacturing of Inconel 625 parts is investigated. Second, a study on the nickel-base superalloy CMSX-4 reveals the formation and dissolution of γ′ precipitates depending on the scan pattern in different part locations. Third, phase transitions during melting and solidification of an intermetallic γ-TiAl based alloy are examined, and the advantages of using thin platelet-shaped specimens to resolve the phase components are discussed. The presented cases give an overview of in situ x-ray diffraction experiments at PETRA III for research on the LPBF technology and provide information on specific experimental procedures.

Operando systems for synchrotron studies of additive manufacturing processes

“…The article contributed by Krohmer et al reports the development of a LPBF simulator for operando synchrotron x-ray scattering experiments, which offers all essential functions of an industrial LPBF system. 6 Also detailed in the article are three application cases, which highlight the unique capabilities of x-ray diffraction and small-angle scattering techniques in characterizing the stress development, precipitates, and phase transition in alloy systems that interest the AM community. These experiments were performed at PETRA III in Germany.…”

In situ observation of crystal rotation in Ni-based superalloy during additive manufacturing process

“…With high temporal and spatial resolutions, synchrotron radiation-based ultrafast X-ray techniques enable the monitoring of microstructural dynamics during the AM process in situ and in real time 17 , 18 . Zhao et al first demonstrated 19 the great potential of ultrafast X-ray imaging and diffraction in characterising microscale defects and structures during the AM process.…”