Design and characterization of a novel Cu2.3Al1.3Ni1.7SnCr0.3 multi-principal element alloy coating on magnesium alloy by laser cladding

Abstract

The evaporation and dilution of substrate seriously limit the performance of laser cladding coatings on magnesium alloys. In order to overcome the above shortcomings, a multi-step ultrasonic assisted laser remelting technology was proposed to improve the performance of the coating. In this work, a novel Cu2.3Al1.3Ni1.7SnCr0.3 multi-principal element alloy coating (MPEAC) was prepared on the surface of magnesium alloy. Characterization techniques such as transmission electron microscopy (TEM), electron back scatter diffraction (EBSD) and scanning electron microscopy (SEM) were employed to characterize the microstructure and phase composition of the coatings. And the phase structure and morphology at the interface between the coating and the substrate were also studied via focus ion beam (FIB) and TEM method. In addition, the corrosion and wear resistance ability of the coatings were monitored by potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS), hardness and friction tests. The results show that Cu2.3Al1.3Ni1.7SnCr0.3 MPEAC with ultrasonic assisted is composed of FCC phase and eutectic phases (Cu10Sn3 and Cu2Ni3Sn3). Due to the forced convection generated by ultrasonic waves, some Cu and Ni phases are precipitated around Cu2Ni3Sn3 phases, which is beneficial to enhance the corrosion resistance. Because of the grain refinement effect caused by ultrasonic, the wear resistance of the coating is also improved. Furthermore, ultrasonic vibration can effectively weaken and eliminate the texture density of the Cu2.3Al1.3Ni1.7SnCr0.3 MPEAC fabricated by laser cladding.