Novel cost-effective Fe-based high entropy alloys with balanced strength and ductility

Based on the current pseudo-binary design strategy of eutectic high entropy alloy (EHEA), a novel approach to design eutectic or near-eutectic HEA was proposed. The eutectic composition can be experimentally specified through adjusting the atomic content ratio (RI/F) of the intermetallic forming elements to the face-centered cubic (FCC) forming elements in an equiatomic HEA system. This adjustment was done by reducing the contents of intermetallic forming elements (Mo and Cr) and accordingly increasing the content of FCC forming element (Fe). Based on this new design strategy, a cost-effective Fe-based near EHEA (Fe45Ni25Cr5Mo25 alloys) were designed and produced after decreasing the RI/F value from 1 to 3/7. The as-cast alloy was associated with compressive strength of 1661 MPa and ductility of 17%. It was considered that the hard trigonal μ phase together with the relatively ductile lamellar eutectic structure were responsible for the high combined properties. In addition, the effects of solute content, Mo and Cr in particular, on the microstructure and mechanical properties of this type of HEAs were also studied.