Extra Strengthening and Work Hardening in Novel Precipitation-Hardened FeCrNiSix Medium-Entropy Alloys

Precipitation strengthening is believed as an important strengthening method that optimizes the strength of alloys. Herein, the possibility of precipitation strengthening is demonstrated by introducing the intermetallic (Cr, Si)-rich sigma phase in the novel FeCrNiSix MEAs system. It is found that simultaneous enhancement in strength and work hardening can be attained by adding Si element in the FeCrNi MEA. Specifically, the FeCrNiSi0.2 alloy realizes a good balance of strength and ductility due to the precipitation of ultrafine- or even nanoscale-sized sigma phase. Moreover, quantitative analyses are conducted to assess the underlying strengthening mechanisms.