Joint CMEC/CDAC Webinar- Prof. Gaia Righi UC San Diego
October 6, 2021
1:00 PM - 2:00 PM
Zoom Link- HTTPS://UCSD.ZOOM.US/J/95665221463
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ABSTRACT: The spall response of pure iron was studied using high power pulsed laser experiments at the LLNL Janus Laser Facility (JLF) and the Dynamic Compression Sector (DCS). Thin iron foils of varying initial microstructures were subjected to peak pressures of 40 – 60 GPa and strain rates ranging from 106 s-1 – 107 s-1. Simultaneous time-resolved free surface velocity measurements and recovery techniques at JLF were used to investigate spall strength and failure mechanisms. At DCS, simultaneous free surface velocity measurements and in-situ X-ray diffraction were used to investigate phase transitions during spall. These uniaxial strain experiments yielded strengths between 5 and 10 GPa for nanocrystalline and single crystal iron, respectively. Post-shock characterization and Molecular Dynamics simulations verify that this difference in strength is due to void initiation sites: grain boundaries in nano and polycrystalline iron and twin boundaries in single crystal iron. The complete α-ϵ phase transition during compression was observed, followed by a rapid transformation back to α-Fe. The grain structure during compression and release/spall failure is still being investigated.
Oct 4, 2021
Oct 4, 2021