Sluggish dendrite growth in an undercooled high entropy alloy

The CoNi, CoFeNi and CoCr_xFeNi (x = 0.2, 0.6, 1) alloys were undercooled and in-situ observed. Sluggish dendrite growth was found for the CoCrFeNi alloy, e.g., the maximum dendrite growth velocity decreases by nearly two orders from the CoNi (78 m s⁻¹) to the CoCrFeNi (0.83 m s⁻¹) alloy. It was shown that it is the Cr element and its adding amount but not the number of components that plays a more decisive role in sluggish dendrite growth. The current work might be helpful for understanding rapid solidification, thereby further controlling the microstructures and modulating the mechanical properties of high entropy alloys.