Abstract
Laser cladding coatings were fabricated on AZ91D magnesium alloy using Al and WC powders with a weight percentage ratio of 95:5, 90:10, and 85:15 by a low power pulsed Nd:YAG laser. During the process of laser cladding, most of WC was decomposed. Tiny white granular resultant Al₁₈Mg₃W₂ was detected in all coatings, while bright white Al₄W particles with clustering tendency were found only in the 10 and 15 wt.% WC coatings because of relatively high WC content. α-Al, α-Mg, Al₃Mg₂, and Al₁₂Mg₁₇ were also detected at the coatings. The hardness of the coatings increased by 3–4 times compared with that of the substrate. The corrosion resistance of the coatings was also improved markedly, mainly the passivation phenomenon was observed in all coatings, which may benefit from the formation of oxidation film Al₂O₃ ⋅ H₂O on the surface of the coatings due to high Al concentration.

Key words
laser cladding, magnesium alloy, corrosion, WC, Al

Full text (1657 KB)