High-temperature age-hardening of a novel cost-effective Fe45Ni25Cr25Mo5 high entropy alloy

Considering the high potential of age-hardening in metastable non-equiatomic high-entropy alloys (HEAs), the high-temperature aging behaviour of a newly developed cost-effective Fe 45 Ni 25 Cr 25 Mo 5 HEA with a face-cantered cubic (FCC) matrix was investigated. The alloy showed high age-hardening response at temperatures up to 900 °C and the peak ageing was obtained at 900 °C for 48 h due to the precipitation of more monoclinic Cr 5.5 Mo 1.5 Fe 6.5 Ni 1.5 -type σ phase. Although the as-cast Fe-enriched HEA composed of FCC and σ phases possessed balanced high tensile strength and ductility compared with previously reported as-cast FCC-dominated HEAs, the peak ageing only led to substantial improvement in compression properties with compression yield strength of 543.7 MPa, ultimate strength of 1098.1 MPa and strain to fracture of 40%. The peak aged alloy exhibited tensile brittleness at room temperature, which was attributed to the restriction of dislocation movement by the precipitation of large needle-shaped intermetallics . Furthermore, the newly developed alloy showed high oxidation and corrosion resistance , which was superior to the 316L stainless steel and was comparable to the Inconel 625 super alloy. Thus, this HEA can be potentially used as a superalloy.