In-situ observations of deformation twins and crack propagation in a CoCrFeNiMn high-entropy alloy

The interaction between crack propagation and twinning structures in an equi-atomic CoCrFeNiMn high-entropy alloy was investigated using in-situ transmission electron microscopy. Crack retardation mechanisms were strongly related with crack length. For a short and sharp crack, crack propagation was mostly retarded by crack deflection at the twin boundary and plastic relaxation resulting from twinning and detwinning. When a crack developed into a longer crack, its propagation was retarded by crack blunting and bridging effects at the deformation twin boundary.