Preparation of nanostructured CoCrFeMnNi high entropy alloy by hot pressing sintering gas atomized powders

•Hot press sintering of gas atomized (GA) CoCrFeMnNi powders exhibits a mass of nano-sized metastable structures.•The metastable structures in sintered bulks are inherited from the GA CoCrFeMnNi powders with nano-crystallites size.•The main strengthening mechanism is attributed to grain refinement and the presence of metastable nano-structures.