Effect of ultrasonic impact treatment on the properties of CoCrFeNiCu high-entropy alloy coatings on steel by induction cladding

Abstract

The aim of this study is to improve the comprehensive properties of CoCrFeNiCu high entropy alloy coating (HEAc) prepared by induction cladding by means of ultrasonic impact treatment (UIT). After UIT, the interdendritic segregation of Cu atoms on the surface of HEAc was inhibited, which made the dual-phase structure consisting of FCC1 Cu-rich phase and FCC2 Cu-depleted phase transform to a single-phase FCC. High density of the dislocation and the sub-grain boundary produced by UIT have hardened the surface of the HEAc, which strengthened microhardness, elastic modulus and wear resistance. The combination of the soft region and the hard region in the HEAc/substrate specimen with UIT made the strength increase but the elongation decrease. The inhibition effect of UIT on the Cu-rich phase alleviated the inhomogeneity of the passivation film, while the grain refinement and high-density dislocation promoted the growth of the passivation film, hindered the invasion of corrosive ions, and effectively improved the corrosion resistance of the HEAc surface.