Rapid solidification of AlCoCrFeNi2.1 High-entropy Alloy

•Rapid solidification of the AlCoCrFeNi2.1 Eutectic High-Entropy Alloy (EHEA) is explored, with cooling rates reaching 1.75×106 K s−1.•The microstructure of AlCoCrFeNi2.1 Eutectic High-Entropy Alloy (EHEA) becomes predominantly dendritic at the highest cooling rates.•Disorder trapping is observed, whereby the rapid cooling inhibits the L12 and B2 ordering observed in the as-cast alloy.•FCC and BCC growth competition is observed and conditions which favour the growth of FCC are explained.•The hall-petch phenomenon is observed, although it is a very weak relation. The conclusion was made that this is due to dominance of the primary FCC. In this work the effect of cooling rate on the dual-phase (L12/B2) AlCoCrFeNi2.1 Eutectic High-Entropy Alloy was investigated. AlCoCrFeNi2.1 powders were made using a drop-tube facility, achieving powders of sizes ranging from 850 µm ≤ d