Investigation on the microstructure and corrosion resistance of AlCoCrFeNi2Cu high-entropy alloy fabricated by laser cladding

In this work, the AlCoCrFeNi₂Cu high-entropy alloy (HEA) has been designed using the pseudo-binary design strategy, and the AlCoCrFeNi₂Cu HEA cladding layer was prepared on the surface of 304 stainless steel by the laser cladding technique. The microstructure, microhardness, and electrochemical corrosion properties of the cladding layer were analyzed in detail. The optimal parameters of the laser power of 2200 W and the scanning sweep rate of 5 mm/s has been obtained. Under this laser cladding process parameters, the surface morphology of the cladding layer not only had slight defects and smooth edges but also had better metallurgical bonding. And the phase composition of the rapidly solidified HEA microstructures has been calculated by the Thermo-Calc software. The simulated results were in good agreement with the experimental results. The AlCoCrFeNi₂Cu HEA cladding layer is composed of matrix phase (FCC (L1₂) phase) and intercrystalline phase (B2 phase), and a Cu-rich phase appears between the two phases. Meanwhile, the properties of the AlCoCrFeNi₂Cu HEA cladding layer have been investigated. The microhardness of the AlCoCrFeNi₂Cu HEA cladding layer is slightly higher than that of the substrate, with a maximum hardness value of 250 HV_0.2. The potentiodynamic polarization curve and EIS test results show that the AlCoCrFeNi₂Cu HEA cladding layer has higher self-corrosion potential, less self-corrosion current density, a larger capacitive reactance arc radius, and an impedance value higher than that of the 304 stainless steel. The corrosion resistance performance is slightly better than that of 304 stainless steel.