Deformation Behaviors of an Additive-Manufactured Ni₃₂Co₃₀Cr₁₀Fe₁₀Al₁₈ Eutectic High Entropy Alloy at Ambient and Elevated Temperatures

Eutectic high-entropy alloys (EHEAs) that have superior formability are attractive for direct laser deposition technology. In this study, a regular-shaped bulk Ni₃₂Co₃₀Cr₁₀Fe₁₀Al₁₈ EHEA without apparent pores and micro-cracks was successfully fabricated by direct laser deposition. The as-deposited alloy showed a high tensile strength of 1.3 GPa with a ductility of 35% at ambient temperature and a tensile strength of 320 MPa at 760 °C. The deformation mechanisms of the as-deposited alloy at ambient and elevated temperatures were investigated by coupling the in-situ tensile test with a scanning electron microscope. It is revealed that the excellent combination of strength and ductility originated from the synergic effects of the FCC and B2 phases in eutectic lamellae. And the generation of cracks along phase boundaries restricted its high-temperature strength above 760 °C.