High strength dual-phase high entropy alloys with a tunable nanolayer thickness

In this work, we have synthesized dual-phase high entropy alloys (DP-HEAs) multilayers with a tunable layer thickness through a bottom-up approach. The DP-HEAs' multilayers reach the maximum hardness of 133 GPa at a critical thickness of 10 nm. The main strengthening mechanism is that dislocation movement is locked by both interior columnar grain boundaries and heterogeneous interfaces. A crystalline-to-amorphous transition occurs when layer thickness is below the critical thickness. The formation of amorphous DP-HEAs deformed by shear transformation zones with collective atomic rearrangement is responsible for the softening behavior. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.