Novel ultra-high aluminum content eutectic high entropy alloys with duplex-reinforced phases and labyrinthine structure

摘要

A multi-synergism method integrating mixing enthalpy, empirical parameters and tests excavate is used to exploit ultra-high aluminum content Al1.75CrFeNi eutectic high entropy alloys (EHEAs). Furthermore, the addition of ultra-high aluminum content promotes the formation of BCC (Cr-Fe) + B2 (NiAl), proving that ultra-high aluminum content can separate more Ni atoms in high-entropy matrix to form duplex-reinforced phases. Al1.75CrFeNi is composed of duplex-reinforced phases (Cr-Fe phase and NiAl phase), which guarantees ultimate compressive mechanical properties for the alloys. Simultaneously, the increasing of aging Al1.75CrFeNi EHEAs' energy density in grain boundary will trigger the switch of as-cast alloys with clear edges and corner to rounded labyrinth structure, which can further heighten Ostwald Ripening effect. It's an advanced theory to ameliorate alloy's ductility from 11.8 to 17.6 by ripening. Likewise, aged Al1.75CrFeNi exhibits ultimate compressive stress and microhardness about 1716.4 MPa and 482.9HV, respectively. The results provide a new theory in chemical composition of EHEAs.