Improved corrosion and wear resistance of Mg alloys via laser surface modification of Al on AZ31B

A highly intense laser beam from a continuous wave diode-pumped ytterbium laser source was used to synthesize a corrosion and wear resistant aluminum coating rich in Al12Mg17 intermetallic phase by direct melting of aluminum precursor powders on AZ31B Mg alloy substrates. The coating composition and microstructure were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high resolution energy diffraction spectroscopy in a transmission electron microscope. From X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy diffraction spectroscopy analysis it was confirmed that laser processing resulted in uniform distribution of a highly corrosion resistance Al12Mg17 intermetallic phase within the coating. The effect of this type of coating on the corrosion and wear resistance of the Mg alloy is investigated in the current study. Under the set of laser processing parameters employed in the current work, no significant change in microstructural and phase evolution and thereby corrosion and wear performance was observed for the laser processed samples. In general improved corrosion resistance was observed for the laser processed samples as compared to the untreated AZ31B. Also, as the precipitation of an intermetallic phase is expected to strain harden the matrix, an improvement in dry sliding wear was observed for the laser processed samples.