Laser Cladding of Al+nano-Al₂O₃ Powder on ZM5 Magnesium Alloy

Abstract

Laser surface cladding was carried out on a Mg-Al-Zn system ZM5 magnesium alloy with a mixture of Al and nano-Al2O3powders. The microstructure, chemical composition analyses of the cladding coating were studied by scanning electron microscopy(SEM), energy dispersive X-ray analysis(EDAX).Both the coating and substrate were identied by microhardness tester. The laser cladding showed very good bonding with the magnesium alloy substrate. The Al2O3particles partially or completely melted during laser irradiation and re-solidified with irregular shapes in the size range of 5–60 µm along with a few islands as large as 500 µm, within the grain-refined Mg-rich dendritic matrix. The improvement in microhardness after cladding was attributed to the presence of ultra-hard Al2O3particles, increased solid solubility of Al and a very fine dendritic microstructure as a result of rapid solidification induced by laser cladding process. And corrosion resistance of the cladded coating was enhanced compared to that of the as-cast substrate after immersion tests.

An Introduction on the Laser Cladding Coatings on Magnesium Alloys

“…The use of nanocomposite coatings has several advantages from the point of view of the tribological properties because the nano particles contribute to increasing the wear and corrosion resistance. Chen et al 2008 researched the effect of laser cladding aluminum metal matrix reinforced with nano SiC particles and, the same authors studied, in 2011, the effect of using nano-Al 2 O 3 particles [48,49]. Nowadays, Sundaraselvan and Senthilkumar [50] have continued to work on these nano-Al 2 O 3 composite coatings.…”