Microstructure and properties of CoCrFeNiMo0.2 high-entropy alloy enhanced by high-current pulsed Electron beam

Abstract Recently, high-entropy alloys have drawn lots of attention due to their outstanding properties. In this paper, a promising new surface modification technique was acted on CoCrFeNiMo0.2 high-entropy alloy to improve its mechanical and corrosion properties. CoCrFeNiMo0.2 high-entropy alloys were synthesized via vacuum arc melting then, their surfaces were processed by high-current pulsed electron beam (HCPEB). Microstructure, microhardness, wear and corrosion resistance were studied systematically by means of X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Before and after HCPEB irradiation, CoCrFeNiMo0.2 high-entropy alloy had a face-centered cubic (FCC) structure, and the surface of the irradiated samples revealed preferential orientation on the (111) and (200) planes. In addition, a compact and homogenization surface layer formed after irradiation. Also, high-amplitude stress caused high-density dislocations and stacking faults on the surface. After HCPEB irradiation, the properties of the samples were significantly improved, the maximum microhardness (392.9 HV) and lowest wear rate (0.92 × 10−4 mm3·N−1·m−1) was obtained after 35-pulsed irradiation. Furthermore, corrosion resistance was obviously enhanced after 25-pulsed irradiation.