Effect of pulsed Nd : YAG laser melting treatment on microstructural and corrosion behaviour of AZ91C Mg alloy

• In the present study, an attempt was made to improve the corrosion resistance and microhardness of a cast magnesium-aluminium-zinc alloy by laser surface melting. A 400 W pulsed Nd:YAG laser was used to melt and rapidly quench the surface of the cast AZ91C alloy to improve the corrosion resistance. This was evaluated using potentiodynamic polarisation and EIS studies. The microstructure of the melt pool was examined using optical microscopy and scanning electron microscopy (SEM) along with energy dispersive spectroscopy (EDS), X-ray diffraction studies (XRD) and X-ray fluorescence (XRF). The work revealed that laser melting improves the corrosion resistance of as cast AZ91C alloy because of its fine microstructure and extensive solubility of aluminium in eutectic (β phase). The microhardness of the laser surface melted layer was also increased from 74 HV to 99-124 HV. © 2006 Institute of Materials, Minerals and Mining.

Nyckelord

AZ91C

Corrosion

Electrochemical measurements

Laser surface melting

Microstructure

Corrosion resistance

Laser pulses

Microhardness

Optical microscopy

Polarization

Scanning electron microscopy

X ray diffraction

X-ray fluorescence (XRF)

Magnesium alloys

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