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Title: 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. We also present experimental results using Ti-6Al-4V, a widely used aerospace alloy, as a model system. Both imaging and diffraction experiments were carried out at the Stanford Synchrotron Radiation Lightsource. Melt pool dynamics were imaged at frame rates up to 4 kHz with a ~1.1 μm effective pixel size and revealed the formation of keyhole pores along the melt track due to vapor recoil forces. Diffraction experiments at sampling rates of 1 kHz captured phase evolution and lattice contraction during the rapid cooling present in LPBF within a ~50 × 100 μm area. In conclusion, we also discuss the utility of these measurements for model validation and process improvement.
Authors:
 [1] ;  [1] ;  [2] ; ORCiD logo [1] ;  [1] ;  [1] ;  [2] ;  [2] ; ORCiD logo [2] ; ORCiD logo [2] ;  [2] ; ORCiD logo [3] ; ORCiD logo [2] ;  [1] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  3. Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-739736
Journal ID: ISSN 0034-6748
Grant/Contract Number:
AC52-07NA27344; CPA 32035; CPA 32037; CPA 32038
Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 89; Journal Issue: 5; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 47 OTHER INSTRUMENTATION
OSTI Identifier:
1438740
Alternate Identifier(s):
OSTI ID: 1435482