The dependence of thermal stability on morphology in eutectic high-entropy alloys.

[Display omitted] • Irregular lamellae in the eutectic CoCrFeNiHf HEA exhibit poor thermal stability. • The existence of orientation relationship between FCC and Laves phases in regular lamellae ensures good thermal stability. • The good thermal stability keeps good plasticity after annealing. In order to explore the thermal stability of eutectic high-entropy alloys (EHEAs), two EHEAs with regular lamellae and irregular lamellae are specifically investigated. Regular lamellae exhibit much better thermal stability than irregular lamellae predominantly due to the existence of an orientation relationship between FCC and Laves phases in the regular lamellae. As a result, the regular lamellae shows relatively constant plasticity after annealing up to 900 °C; whereas, the plasticity is deteriorated in the irregular lamellae due to microstructure coarsening. [ABSTRACT FROM AUTHOR]