Thermal Equation of State Measurements on High Entropy Alloys using Large-Volume Press*

Eutectic high entropy alloys (EHEAs) have been studied for almost a decade now due to their ultrahigh yield strength and high tensile ductility. There have been limited studies on the behavior of EHEAs under extreme conditions of pressures and temperatures. We have performed high pressure studies on dual-phase nanolamellar structure of EHEA AlCoCrFeNi_2.1 synthesized through laser powder-bed fusion (L-PBF). Comparing x-ray diffraction studies on L-PBF printed cylindrical sample up to 5.5GPa (large-volume Paris-Edinburgh cell) to similar studies on L-PBF printed foil in a diamond anvil cell to pressure of 42 GPa  We show the alternating face-centered cubic (FCC) and  (BCC) body-centered cubic nanolamellae structure transform into single phase FCC completing the transformation at 21 ± 3 GPa. The equation of state measured for the FCC phase between both the large-volume press and DAC experiments are in good agreement.