Microstructures and Mechanical Properties of Multi-component AlxCrFe2Ni2Mo0.2 High-Entropy Alloys

A series of AlxCrFe2Ni2Mo0.2 alloy consisting of FCC + BCC phases have been designed, and their as-cast microstructures and mechanical properties were also investigated with x ranging from 0.6 to 0.9. It was found that with the addition of Al element, the solidified structures changed from dendrite to columnar crystal then back to dendrite again. Moreover, the increased amount of BCC phase resulted in finer and more uniform microstructures of FCC [FeCrNi(Mo)] and BCC (Al–Ni) phases. Tensile yield strength and hardness of alloys showed a similar increasing trend as the volume fraction of BCC phase increased. Both strain hardening rate and strain hardening exponent were calculated to assess the tensile properties of the alloys. It was shown that Al0.6CrFe2Ni2Mo0.2 exhibited the most excellent and comprehensive mechanical properties due to its high work hardening ability and stable strain hardening rate. The product of strength and elongation of Al0.6CrFe2Ni2Mo0.2 reached up to 38.6 GPa%, which was higher than most of the reported as-cast high-entropy alloys.