Eutectic high entropy alloy (EHEA) AlCoCrFeNi2.1, additively manufactured through laser powder bed fusion, has both high strength and ductility due to its far-from-equilibrium, dual-phase nanolamellar structure consisting of both fcc and bcc phases [1]. Understanding high pressure behavior of EHEAs is essential both for industrial applications and for understanding the underlying physics of the high-entropy systems. In this work, we performed in situ X-ray diffraction on additively manufactured EHEA AlCoCrFeNi2.1 under high strain rate laser-driven shock compression at EH5-BL3 of SACLA. The initial dual-phase structure gave way to an fcc-only structure when shock-compressed up to 247 GPa, and to a liquid phase when shocked above 265 GPa. Upon the subsequent pressure release from both the fcc-only and liquid phases, the material back-transformed to a dual-phase bcc/fcc structure. The relative fractions of bcc and fcc phases upon release were influenced by the peak stress under shock compression, revealing the role of rapid kinetics on these structural transformations.
This work was supported by the Department of Energy’s National Nuclear Security Administration under Award No. DE-NA0004090. The experiments were performed at BL3 of SACLA with the approval of the Japan Synchrotron Radiation Research Institute (proposal no. 2023A8016).
