Fabrication of FexCoCrAlNi medium and high entropy layers on a carbon steel through TIG cladding

Abstract

FexCoCrAlNi medium and high entropy layers were fabricated on a carbon steel using multilayer TIG cladding. The Fe content of the deposited layers decreased by moving away from the substrate due to the dilution effect. FexCoCrAlNi (with x>1) medium entropy alloys (MEAs) with a major Fe-rich BCC and minor Fe–Al–Ni-rich FCC phases developed in the inner parts of the fabricated layers. No intermetallic compounds appeared in MEAs. Microstructural assessments revealed that a FeCoCrAlNi high entropy alloy (HEA) containing Al–Ni-rich BCC and Fe–Cr-rich FCC crystal structures was achieved in the upper part of the deposited layers. It was found that Fe–Cr and Al–Ni pairs had contradictory effects on stabilizing crystal structure in MEAs and HEA. The Al–Ni pair was FCC-phase stabilizer in MEA while it was responsible for the formation of BCC phase in HEA. The microhardness of the deposited layers increased successively to reach 430 HV in the HEA due to the solid solution strengthening and formation of BCC phase with high-entropy characteristics.