Micro-mechanical deformation behavior of CoCrFeMnNi high-entropy alloy

•Micro-mechanical deformation behavior of CoCrFeMnNi high entropy alloy was investigated.•Tensile strength and uniform elongation are independent of samples size despite lower total elongation at micro-scale.•CoCrFeMnNi exhibits a strain-rate dependent serrated deformation behavior at elevated temperature.•Microstructural evolution in terms of dislocation configurations was correlated to the occurrence of serrated deformation.