Microstructure and corrosion properties of FeCoNiCrMn high entropy alloy coatings prepared by high speed laser cladding and ultrasonic surface mechanical rolling treatment

The FeCoNiCrMn high-entropy alloy (HEA) coatings were prepared by high-speed laser cladding (HSLC) technology, and the surface was subjected to ultrasonic surface mechanical rolling treatment (SMRT). After SMRT, the surface of the coatings show a gradient structure. The coatings consist of planar crystal, columnar dendrites and equiaxed crystals from inside to outside. Corrosion behavior in a 3.5% NaCl solution indicates that SMRTed coatings exhibit higher corrosion resistance than the coatings without SMRT. Anti-corrosion mechanism was discussed based on grain refinement, grain boundary wetting phase transitions and compressive residual stress.