TY  - JOUR
AU  - Taylor, Zane
AU  - Reddy, Tharun
AU  - Fang, Lichao
AU  - Oppermann, Patrick
AU  - Kramer, Patrick L.
AU  - Decker, Franz-Josef
AU  - Seaberg, Matthew
AU  - Chollet, Matthieu
AU  - van Driel, Tim
AU  - Halavanau, Alex
AU  - Hart, Philip
AU  - Dayton, Matthew
AU  - Seiboth, Frank
AU  - Wang, Wenxin
AU  - Gee, Carolyn
AU  - Wilson, Abigail
AU  - Margraf-O'Neal, Rachel
AU  - Chatterjee, Gourab
AU  - Chen, Ying
AU  - Molesky, Ilana J. P.
AU  - Wang, Yifan
AU  - Irvine, Sara
AU  - Stanton, Jade
AU  - Melendrez, Cynthia
AU  - Banta, Kelsey
AU  - Nelson, Silke
AU  - Thampy, Vivek
AU  - Katagiri, Kento
AU  - Haubro, Morten
AU  - Liu, Sen
AU  - Pal, Dayeeta
AU  - Moghimi, Lauren
AU  - Tassone, Christopher
AU  - Dresselhaus-Marais, Leora
TI  - High-resolution in situ characterization of laser powder bed fusion via transmission X-ray microscopy at X-ray free-electron lasers
JO  - Journal of synchrotron radiation
VL  - 32
IS  - 3
SN  - 0909-0495
CY  - Chester
PB  - IUCr
M1  - PUBDB-2025-01220
SP  - 524 - 533
PY  - 2025
AB  - In this work, we describe the instrumentation used to perform the first operando transmission X-ray microscopy (TXM) and simultaneous X-ray diffraction of laser melting simulating laser powder bed fusion on the XCS instrument at the Linac Coherent Light Source (LCLS) X-ray free-electron laser (XFEL). Our TXM with 40× magnification in the X-ray regime at 11 keV gave spatial resolutions down to 940 nm per line pair, with effective pixel sizes down to 206 nm, image integration times of <100 fs, and frame rates tunable between 2.1 and 119 ns for two probe frames (0.48 GHz to 8.4 MHz). Images were recorded on Zyla and Icarus (UXI) detectors to trade off between spatial resolution and time dynamics. A 1 kW CW IR laser was coupled into the interaction point to conduct pump–probe studies of laser melting and solidification dynamics. Our temporal and spatial resolution with attenuation-based contrast exceeds that currently possible with synchrotron-based high-speed radiography. This system was sensitive to feature velocities of 10–12000 m s<sup>−1</sup> but we did not observe any motion in this range in the laser melting of Al6061 alloy. Shockwaves were not observed and hot cracking proceeded at velocities below the detection limits. Pore accumulation was observed between successive shots, indicating that bubble escape mechanisms were not active. With proper experimental design, the spatial resolution, contrast and field of view could be further improved or modified. The increased brightness and narrower bandwidth of the XFEL allowed for this imaging technique and it lays the groundwork for a wide range of operando techniques to study additive manufacturing. 
LB  - PUB:(DE-HGF)16
C6  - pmid:40167485
UR  - <Go to ISI:>//WOS:001486450700002
DO  - DOI:10.1107/S1600577525001675
UR  - https://bib-pubdb1.desy.de/record/625895
ER  -