Equation of state of additively manufactured eutectic high entropy alloy up to 302 GPa

High entropy alloys (HEAs) are an attractive class of material, with many HEAs having superior mechanical properties compared to traditional alloys. We report an angle dispersive x-ray diffraction experiment of the eutectic dual-phase [face-centered cubic (FCC) and body-centered cubic (BCC)] HEA AlCoCrFeNi_2.1, which consists of alternating lamellae of FCC and BCC microstructures (Ren, J. et al. Nature 608, 62–68, 2022). Using a diamond anvil cell at ambient temperature at the Advanced Photon Source (HPCAT), we achieve a peak pressure of 302 GPa, as measured with a tungsten pressure marker. While the BCC phase irreversibly transforms by a pressure of 21±3 GPa (Pope, A. D. et al. AIP Adv., submitted), the FCC phase is stable throughout. The resulting pressure-volume isotherm for the FCC phase is well-described by a third-order Birch-Murnaghan equation of state with V₀ = 11.528 ų/atom, K₀ = 190 GPa and K₀' = 4.07.