Abstract
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The CrCoNi medium-entropy alloy is not fully utilized at room temperature circumstance due to its low strength, despite excellent cryogenic mechanical properties. Here we report that, a superior room temperature strength (1.6 GPa and 407.6 Hv) has been obtained in the single phase CoCrNi medium-entropy alloy, by carefully tuning the formation of multiple lattice defects. Electron microscopy characterizations show that such high-strength CoCrNi alloy contains favorable heterostructures of coarsening grains (~30 ��m) and ultrafine grains (~1 ��m), together with the high density of dislocation cells, small stacking faults, ultrafine nanotwins (~9 nm in thickness) and Lomer���Cottrell locks.