Strong yet ductile eutectic high-entropy FCC/Laves composite fabricated by powder plasma arc additive manufacturing: Mechanical property, microstructure evolution, and constitutive description over a wide range of temperatures and strain rates

To enhance the strength and toughness of metallic materials simultaneously over a wide range of temperatures and strain rates, a eutectic high-entropy FCC/Laves composite with a heterogeneous initial microstructure was fabricated by powder plasma arc additive manufacturing. The mechanical behavior of the composite over a wide range of temperatures and strain rates was tested with the aid of an electronic universal testing machine and an improved Split Hopkinson pressure bar. The high-entropy FCC/Laves composite possesses a unique combination of strength and ductility over the selected temperature and strain rate ranges due to the in situ composite nature with both soft high-entropy FCC phase and hard high-entropy Laves phase. Complicated thermal viscoplastic behavior is presented. To reveal the mechanisms of the complicated thermal viscoplastic behavior, microstructure evolution was characterized. The high-entropy Laves phase, as a kind of multi-component intermetallic, defies convention by displaying plastic deformation at room temperature and different strain rates. Superior damage tolerance of the high-entropy FCC/Laves composite can be achieved over the selected temperature and strain rate ranges with the contribution of deformation twin in FCC phase, as well as dynamic recrystallization over high temperature range. Finally, a constitutive description was developed, which is shown to be able to accurately describe the complicated plastic behavior over a wide range of temperatures and strain rates. These findings suggest promising prospects for advanced material design, opening a new avenue to achieve a fine balance between strength and ductility across different conditions.