Design of precipitation (γ’) strengthened Fe-rich medium entropy alloys

A novel Fe-rich medium entropy alloy (MEA) space with a γ+γ’-only phase field at 800 °C is proposed where the volume fraction and dissolution temperature of γ’-phase can be tuned by substituting Fe for Ni/Co and Cr. The γ+γ’-structured Fe-35.5Ni-4Cr-6.3Al-3.2Ti alloy (Fe-content of 51 at.%; γ’-volume fraction of 24%) after a recrystallisation and ageing treatment displays a yield strength of 902 MPa, ultimate strength of 1370 MPa and a tensile ductility of 24%. The presented alloy space progresses towards the development of Fe-rich MEAs with good strength retention (>600 °C) for heat-resistant structural applications.